text:
Isotopes of seaborgium

Seaborgium (106Sg) is a synthetic element and so has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was 263Sg in 1974. There are thirteen known radioisotopes from 258Sg to 271Sg and five known isomers (259mSg, 261mSg, 263mSg, 265mSg, and 267mSg). The longest-lived isotopes are 267Sg with a half-life of 9.8 minutes and 269Sg with a half-life of 5 minutes. Due to a low number of measurements, and the consequent overlapping measurement uncertainties at the confidence level corresponding to one standard deviation, a definite assignment of the most stable isotope cannot be made.

List of isotopes

 * 258Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 152
 * 258.11298(44)#
 * 2.7(5) ms [$2.6 ms$]
 * SF
 * (various)
 * 0+
 * rowspan=3|259Sg
 * rowspan=3 style="text-align:right" | 106
 * rowspan=3 style="text-align:right" | 153
 * rowspan=3|259.11440(13)#
 * rowspan=3|402(56) ms
 * α
 * 255Rf
 * rowspan=3|(11/2−)
 * β+ (<1%)
 * 259Db
 * SF (rare)
 * (various)
 * rowspan=3 style="text-indent:1em" | 259mSg
 * rowspan=3 colspan="3" style="text-indent:2em" |87 keV
 * rowspan=3|226(27) ms
 * α (97%)
 * 261Sg
 * rowspan=3|(1/2+)
 * SF (3%)
 * (various)
 * β+ (<1%)
 * 259Db
 * rowspan=2|260Sg
 * rowspan=2 style="text-align:right" | 106
 * rowspan=2 style="text-align:right" | 154
 * rowspan=2|260.114384(22)
 * rowspan=2|4.95(33) ms
 * SF (71%)
 * (various)
 * rowspan=2|0+
 * α (29%)
 * 256Rf
 * rowspan=3|261Sg
 * rowspan=3 style="text-align:right" | 106
 * rowspan=3 style="text-align:right" | 155
 * rowspan=3|261.115949(20)
 * rowspan=3|183(5) ms
 * α (98.1%)
 * 257Rf
 * rowspan=3|(3/2+)
 * β+ (1.3%)
 * 261Db
 * SF (0.6%)
 * (various)
 * style="text-indent:1em" | 261mSg
 * colspan="3" style="text-indent:2em" |100(50)# keV
 * 9.3(1.8) μs [$9 μs$]
 * IT
 * 261Sg
 * 7/2+#
 * rowspan=2|262Sg
 * rowspan=2 style="text-align:right" | 106
 * rowspan=2 style="text-align:right" | 156
 * rowspan=2|262.11634(4)
 * rowspan=2|10.3(1.7) ms
 * SF (94%)
 * (various)
 * rowspan=2|0+
 * α (6%)
 * 258Rf
 * rowspan=2|263Sg
 * rowspan=2 style="text-align:right" | 106
 * rowspan=2 style="text-align:right" | 157
 * rowspan=2|263.11829(10)#
 * rowspan=2|940(140) ms
 * α (87%)
 * 259Rf
 * rowspan=2|9/2+#
 * SF (13%)
 * (various)
 * style="text-indent:1em" | 263mSg
 * colspan="3" style="text-indent:2em" | 51(19)# keV
 * 420(100) ms
 * α
 * 259Rf
 * 3/2+#
 * 264Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 158
 * 264.11893(30)#
 * 37 ms
 * SF
 * (various)
 * 0+
 * 265Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 159
 * 265.12109(13)#
 * α
 * 261Rf
 * style="text-indent:1em" | 265mSg
 * colspan="3" style="text-indent:2em" |
 * α
 * 261mRf
 * 266Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 160
 * 266.12198(26)#
 * 390(110) ms
 * SF
 * (various)
 * 0+
 * 267Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 161
 * 267.12436(30)#
 * α
 * 263mRf
 * 9/2#
 * style="text-indent:1em" | 267mSg
 * colspan="3" style="text-indent:2em" | 110 keV#
 * SF
 * (various)
 * 1/2#
 * 268Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 162
 * 268.12539(50)#
 * SF
 * (various)
 * 0+
 * 269Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 163
 * 269.12863(39)#
 * α
 * 265Rf
 * rowspan=2|271Sg
 * rowspan=2 style="text-align:right" | 106
 * rowspan=2 style="text-align:right" | 165
 * rowspan=2|271.13393(63)#
 * rowspan=2|$8.5 s$
 * α (73%)
 * 267Rf
 * rowspan=2|3/2+#
 * SF (27%)
 * (various)
 * style="text-indent:1em" | 267mSg
 * colspan="3" style="text-indent:2em" | 110 keV#
 * SF
 * (various)
 * 1/2#
 * 268Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 162
 * 268.12539(50)#
 * SF
 * (various)
 * 0+
 * 269Sg
 * style="text-align:right" | 106
 * style="text-align:right" | 163
 * 269.12863(39)#
 * α
 * 265Rf
 * rowspan=2|271Sg
 * rowspan=2 style="text-align:right" | 106
 * rowspan=2 style="text-align:right" | 165
 * rowspan=2|271.13393(63)#
 * rowspan=2|$14.4 s$
 * α (73%)
 * 267Rf
 * rowspan=2|3/2+#
 * SF (27%)
 * (various)
 * rowspan=2 style="text-align:right" | 165
 * rowspan=2|271.13393(63)#
 * rowspan=2|$9.8 min$
 * α (73%)
 * 267Rf
 * rowspan=2|3/2+#
 * SF (27%)
 * (various)
 * (various)

Cold fusion
''This section deals with the synthesis of nuclei of seaborgium by so-called "cold" fusion reactions. These are processes that create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only.''

208Pb(54Cr,xn)262−xSg (x=1,2,3)
The first attempt to synthesise seaborgium in cold fusion reactions was performed in September 1974 by a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna. They reported producing a 0.48 s spontaneous fission (SF) activity, which they assigned to the isotope 259Sg. Based on later evidence it was suggested that the team most likely measured the decay of 260Sg and its daughter 256Rf. The TWG concluded that, at the time, the results were insufficiently convincing.

The Dubna team revisited this problem in 1983–1984 and were able to detect a 5 ms SF activity assigned directly to 260Sg.

The team at GSI studied this reaction for the first time in 1985 using the improved method of correlation of genetic parent-daughter decays. They were able to detect 261Sg (x=1) and 260Sg and measured a partial 1n neutron evaporation excitation function.

In December 2000, the reaction was studied by a team at GANIL, France; they were able to detect 10 atoms of 261Sg and 2 atoms of 260Sg to add to previous data on the reaction.

After a facility upgrade, the GSI team measured the 1n excitation function in 2003 using a metallic lead target. Of significance, in May 2003, the team successfully replaced the lead-208 target with more resistant lead(II) sulfide targets (PbS), which will allow more intense beams to be used in the future. They were able to measure the 1n,2n and 3n excitation functions and performed the first detailed alpha-gamma spectroscopy on the isotope 261Sg. They detected ~1600 atoms of the isotope and identified new alpha lines as well as measuring a more accurate half-life and new EC and SF branchings. Furthermore, they were able to detect the K X-rays from the daughter rutherfordium isotope for the first time. They were also able to provide improved data for 260Sg, including the tentative observation of an isomeric level. The study was continued in September 2005 and March 2006. The accumulated work on 261Sg was published in 2007. Work in September 2005 also aimed to begin spectroscopic studies on 260Sg.

The team at the LBNL recently restudied this reaction in an effort to look at the spectroscopy of the isotope 261Sg. They were able to detect a new isomer, 261mSg, decaying by internal conversion into the ground state. In the same experiment, they were also able to confirm a K-isomer in the daughter 257Rf, namely 257m2Rf.

207Pb(54Cr,xn)261−xSg (x=1,2)
The team at Dubna also studied this reaction in 1974 with identical results as for their first experiments with a lead-208 target. The SF activities were first assigned to 259Sg and later to 260Sg and/or 256Rf. Further work in 1983–1984 also detected a 5 ms SF activity assigned to the parent 260Sg.

The GSI team studied this reaction for the first time in 1985 using the method of correlation of genetic parent-daughter decays. They were able to positively identify 259Sg as a product from the 2n neutron evaporation channel.

The reaction was further used in March 2005 using PbS targets to begin a spectroscopic study of the even-even isotope 260Sg.

206Pb(54Cr,xn)260−xSg
This reaction was studied in 1974 by the team at Dubna. It was used to assist them in their assignment of the observed SF activities in reactions using Pb-207 and Pb-208 targets. They were unable to detect any SF, indicating the formation of isotopes decaying primarily by alpha decay.

208Pb(52Cr,xn)260−xSg (x=1,2)
The team at Dubna also studied this reaction in their series of cold fusion reactions performed in 1974. Once again they were unable to detect any SF activities. The reaction was revisited in 2006 by the team at LBNL as part of their studies on the effect of the isospin of the projectile and hence the mass number of the compound nucleus on the yield of evaporation residues. They were able to identify 259Sg and 258Sg in their measurement of the 1n excitation function.

209Bi(51V,xn)260−xSg (x=2)
The team at Dubna also studied this reaction in their series of cold fusion reactions performed in 1974. Once again they were unable to detect any SF activities. In 1994, the synthesis of seaborgium was revisited using this reaction by the GSI team, in order to study the new even-even isotope 258Sg. Ten atoms of 258Sg were detected and decayed by spontaneous fission.

Hot fusion
''This section deals with the synthesis of nuclei of seaborgium by so-called "hot" fusion reactions. These are processes that create compound nuclei at high excitation energy (~40–50 MeV, hence "hot"), leading to a reduced probability of survival from fission and quasi-fission. The excited nucleus then decays to the ground state via the emission of 3–5 neutrons.''

238U(30Si,xn)268−xSg (x=3,4,5,6)
This reaction was first studied by Japanese scientists at the Japan Atomic Energy Research Institute (JAERI) in 1998. They detected a spontaneous fission activity, which they tentatively assigned to the new isotope 264Sg or 263Db, formed by EC of 263Sg. In 2006, the teams at GSI and LBNL both studied this reaction using the method of correlation of genetic parent-daughter decays. The LBNL team measured an excitation function for the 4n,5n and 6n channels, whilst the GSI team were able to observe an additional 3n activity. Both teams were able to identify the new isotope 264Sg, which decayed with a short lifetime by spontaneous fission.

248Cm(22Ne,xn)270−xSg (x=4?,5)
In 1993, at Dubna, Yuri Lazarev and his team announced the discovery of long-lived 266Sg and 265Sg produced in the 4n and 5n channels of this nuclear reaction following the search for seaborgium isotopes suitable for a first chemical study. It was announced that 266Sg decayed by 8.57 MeV alpha-particle emission with a projected half-life of ~20 s, lending strong support to the stabilising effect of the Z = 108, N = 162 closed shells. This reaction was studied further in 1997 by a team at GSI and the yield, decay mode and half-lives for 266Sg and 265Sg have been confirmed, although there are still some discrepancies. In the synthesis of 270Hs (see hassium), 266Sg was found to undergo exclusively SF with a short half-life (TSF = 360 ms). It is possible that this is the ground state, (266gSg) and that the other activity, produced directly, belongs to a high spin K-isomer, 266mSg, but further results are required to confirm this.

A recent re-evaluation of the decay characteristics of 265Sg and 266Sg has suggested that all decays to date in this reaction were in fact from 265Sg, which exists in two isomeric forms. The first, 265aSg has a principal alpha-line at 8.85 MeV and a calculated half-life of 8.9 s, while 265bSg has a decay energy of 8.70 MeV and a half-life of 16.2 s. Both isomeric levels are populated when produced directly. Data from the decay of 269Hs indicates that 265bSg is produced during the decay of 269Hs and that 265bSg decays into the shorter-lived 261gRf isotope. This contradicts the assignment of the long-lived alpha activity to 266Sg, instead suggesting that 266Sg undergoes fission in a short time.

Regardless of these assignments, the reaction has been successfully used in the recent attempts to study the chemistry of seaborgium (see below).

249Cf(18O,xn)267−xSg (x=4)
The synthesis of seaborgium was first realized in 1974 by the LBNL/LLNL team. In their discovery experiment, they were able to apply the new method of correlation of genetic parent-daughter decays to identify the new isotope 263Sg. In 1975, the team at Oak Ridge were able to confirm the decay data but were unable to identify coincident X-rays in order to prove that seaborgium was produced. In 1979, the team at Dubna studied the reaction by detection of SF activities. In comparison with data from Berkeley, they calculated a 70% SF branching for 263Sg. The original synthesis and discovery reaction was confirmed in 1994 by a different team at LBNL.

Decay products
Isotopes of seaborgium have also been observed in the decay of heavier elements. Observations to date are summarised in the table below:

266Sg
Initial work identified an 8.63 MeV alpha-decaying activity with a half-life of ~21 s and assigned to the ground state of 266Sg. Later work identified a nuclide decaying by 8.52 and 8.77 MeV alpha emission with a half-life of ~21 s, which is unusual for an even-even nuclide. Recent work on the synthesis of 270Hs identified 266Sg decaying by SF with a short 360 ms half-life. The recent work on 277Cn and 269Hs has provided new information on the decay of 265Sg and 261Rf. This work suggested that the initial 8.77 MeV activity should be reassigned to 265Sg. Therefore, the current information suggests that the SF activity is the ground state and the 8.52 MeV activity is a high spin K-isomer. Further work is required to confirm these assignments. A recent re-evaluation of the data has suggested that the 8.52 MeV activity should be associated with 265Sg and that 266Sg only undergoes fission.

265Sg
The recent direct synthesis of 265Sg resulted in four alpha-lines at 8.94, 8.84, 8.76 and 8.69 MeV with a half-life of 7.4 seconds. The observation of the decay of 265Sg from the decay of 277Cn and 269Hs indicated that the 8.69 MeV line may be associated with an isomeric level with an associated half-life of ~ 20 s. It is plausible that this level is causing confusion between assignments of 266Sg and 265Sg since both can decay to fissioning rutherfordium isotopes.

A recent re-evaluation of the data has indicated that there are indeed two isomers, one with a principal decay energy of 8.85 MeV with a half-life of 8.9 s, and a second isomer that decays with energy 8.70 MeV with a half-life of 16.2 s.

263Sg
The discovery synthesis of 263Sg resulted in an alpha-line at 9.06 MeV. Observation of this nuclide by decay of 271gDs,271mDs and 267Hs has confirmed an isomer decaying by 9.25 MeV alpha emission. The 9.06 MeV decay was also confirmed. The 9.06 MeV activity has been assigned to the ground state isomer with an associated half-life of 0.3 s. The 9.25 MeV activity has been assigned to an isomeric level decaying with a half-life of 0.9 s.

Recent work on the synthesis of 271g,mDs was resulted in some confusing data regarding the decay of 267Hs. In one such decay, 267Hs decayed to 263Sg, which decayed by alpha emission with a half-life of ~ 6 s. This activity has not yet been positively assigned to an isomer and further research is required.

269Sg
In the claimed synthesis of 293Og in 1999 the isotope 269Sg was identified as a daughter product. It decayed by 8.74 MeV alpha emission with a half-life of 22 s. The claim was retracted in 2001. This isotope was finally created in 2010.

Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing seaborgium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

Hot fusion
The table below provides cross-sections and excitation energies for hot fusion reactions producing seaborgium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

title: Isotopes of seaborgium


text:
Isotopes of bohrium

Bohrium (107Bh) is an artificial element. Like all artificial elements, it has no stable isotopes, and a standard atomic weight cannot be given. The first isotope to be synthesized was 262Bh in 1981. There are 11 known isotopes ranging from 260Bh to 274Bh, and 1 isomer, 262mBh. The longest-lived isotope is 270Bh with a half-life of 2.4 minutes, although the unconfirmed 278Bh may have an even longer half-life of about 690 seconds.

List of isotopes

 * 260Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 153
 * 260.12166(26)#
 * 41(14) ms [$35 ms$]
 * α
 * 256Db
 * rowspan=2|261Bh
 * rowspan=2 style="text-align:right" | 107
 * rowspan=2 style="text-align:right" | 154
 * rowspan=2|261.121400(190)
 * rowspan=2|12.8(3.2) ms [$11.8 ms$]
 * α
 * 257Db
 * rowspan=2|(5/2−)
 * SF (rare)
 * (various)
 * rowspan=3|262Bh
 * rowspan=3 style="text-align:right" | 107
 * rowspan=3 style="text-align:right" | 155
 * rowspan=3|262.122650(100)
 * rowspan=3|$135 ms$
 * α (>94.9%)
 * 258Db
 * rowspan=3|
 * β+ (<3.0%)
 * 262Sg
 * SF (2.1%)
 * (various)
 * style="text-indent:1em" | 262mBh
 * colspan="3" style="text-indent:2em" | 220(50) keV
 * α
 * 258Db
 * rowspan=2|264Bh
 * rowspan=2 style="text-align:right" | 107
 * rowspan=2 style="text-align:right" | 157
 * rowspan=2|264.12459(19)#
 * rowspan=2|1.07(21) s
 * α (85%)
 * 260Db
 * rowspan=2|
 * SF(β+?) (15%)
 * (various)
 * 265Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 158
 * 265.12491(25)#
 * 1.19(52) s [$13.2 ms$]
 * α
 * 261Db
 * rowspan=2|266Bh
 * rowspan=2 style="text-align:right" | 107
 * rowspan=2 style="text-align:right" | 159
 * rowspan=2|266.12679(18)#
 * rowspan=2|$0.94 s$
 * α
 * 262Db
 * rowspan=2|
 * β+?
 * 266Sg
 * 267Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 160
 * 267.12750(28)#
 * 22(10) s [$10 s$]
 * α
 * 263Db
 * 270Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 163
 * 270.13336(31)#
 * α
 * 266Db
 * 271Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 164
 * 271.13526(48)#
 * α
 * 267Db
 * 272Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 165
 * 272.13826(58)#
 * α
 * 268Db
 * 274Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 167
 * 274.14355(65)#
 * 57(27) s [$17 s$]
 * α
 * 270Db
 * 278Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 171
 * 11.5 min?
 * SF
 * (various)
 * 271.13526(48)#
 * α
 * 267Db
 * 272Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 165
 * 272.13826(58)#
 * α
 * 268Db
 * 274Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 167
 * 274.14355(65)#
 * 57(27) s [$2.4 min$]
 * α
 * 270Db
 * 278Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 171
 * 11.5 min?
 * SF
 * (various)
 * 278Bh
 * style="text-align:right" | 107
 * style="text-align:right" | 171
 * 11.5 min?
 * SF
 * (various)
 * 11.5 min?
 * SF
 * (various)

Nucleosynthesis
Superheavy elements such as bohrium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of bohrium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.

Depending on the energies involved, the former are separated into "hot" and "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50−MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, thus allowing for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z = 107.

Cold fusion
Before the first successful synthesis of hassium in 1981 by the GSI team, the synthesis of bohrium was first attempted in 1976 by scientists at the Joint Institute for Nuclear Research at Dubna using this cold fusion reaction. They detected two spontaneous fission activities, one with a half-life of 1–2 ms and one with a half-life of 5 s. Based on the results of other cold fusion reactions, they concluded that they were due to 261Bh and 257Db respectively. However, later evidence gave a much lower SF branching for 261Bh reducing confidence in this assignment. The assignment of the dubnium activity was later changed to 258Db, presuming that the decay of bohrium was missed. The 2 ms SF activity was assigned to 258Rf resulting from the 33% EC branch. The GSI team studied the reaction in 1981 in their discovery experiments. Five atoms of 262Bh were detected using the method of correlation of genetic parent-daughter decays. In 1987, an internal report from Dubna indicated that the team had been able to detect the spontaneous fission of 261Bh directly. The GSI team further studied the reaction in 1989 and discovered the new isotope 261Bh during the measurement of the 1n and 2n excitation functions but were unable to detect an SF branching for 261Bh. They continued their study in 2003 using newly developed bismuth(III) fluoride (BiF3) targets, used to provide further data on the decay data for 262Bh and the daughter 258Db. The 1n excitation function was remeasured in 2005 by the team at the Lawrence Berkeley National Laboratory (LBNL) after some doubt about the accuracy of previous data. They observed 18 atoms of 262Bh and 3 atoms of 261Bh and confirmed the two isomers of 262Bh.

In 2007, the team at LBNL studied the analogous reaction with chromium-52 projectiles for the first time to search for the lightest bohrium isotope 260Bh:

The team successfully detected 8 atoms of 260Bh decaying by alpha decay to 256Db, emitting alpha particles with energy 10.16 MeV. The alpha decay energy indicates the continued stabilizing effect of the N=152 closed shell.

The team at Dubna also studied the reaction between lead-208 targets and manganese-55 projectiles in 1976 as part of their newly established cold fusion approach to new elements:

They observed the same spontaneous fission activities as those observed in the reaction between bismuth-209 and chromium-54 and again assigned them to 261Bh and 257Db. Later evidence indicated that these should be reassigned to 258Db and 258Rf (see above). In 1983, they repeated the experiment using a new technique: measurement of alpha decay from a decay product that had been separated out chemically. The team were able to detect the alpha decay from a decay product of 262Bh, providing some evidence for the formation of bohrium nuclei. This reaction was later studied in detail using modern techniques by the team at LBNL. In 2005 they measured 33 decays of 262Bh and 2 atoms of 261Bh, providing an excitation function for the reaction emitting one neutron and some spectroscopic data of both 262Bh isomers. The excitation function for the reaction emitting two neutrons was further studied in a 2006 repeat of the reaction. The team found that the reaction emitting one neutron had a higher cross section than the corresponding reaction with a 209Bi target, contrary to expectations. Further research is required to understand the reasons.

Hot fusion
The reaction between uranium-238 targets and phosphorus-31 projectiles was first studied in 2006 at the LBNL as part of their systematic study of fusion reactions using uranium-238 targets:

 * + →  + 5

Results have not been published but preliminary results appear to indicate the observation of spontaneous fission, possibly from 264Bh.

Recently, the team at the Institute of Modern Physics (IMP), Lanzhou, have studied the nuclear reaction between americium-243 targets and accelerated nuclei of magnesium-26 in order to synthesise the new isotope 265Bh and gather more data on 266Bh:

 * + →  + x  (x = 3, 4, or 5)

In two series of experiments, the team measured partial excitation functions for the reactions emitting three, four, and five neutrons.

The reaction between targets of curium-248 and accelerated nuclei of sodium-23 was studied for the first time in 2008 by the team at RIKEN, Japan, in order to study the decay properties of 266Bh, which is a decay product in their claimed decay chains of nihonium:

 * + →  + x  (x = 4 or 5)

The decay of 266Bh by the emission of alpha particles with energies of 9.05–9.23 MeV was further confirmed in 2010.

The first attempts to synthesize bohrium by hot fusion pathways were performed in 1979 by the team at Dubna, using the reaction between accelerated nuclei of neon-22 and targets of berkelium-249:

 * + →  + x  (x = 4 or 5)

The reaction was repeated in 1983. In both cases, they were unable to detect any spontaneous fission from nuclei of bohrium. More recently, hot fusions pathways to bohrium have been re-investigated in order to allow for the synthesis of more long-lived, neutron rich isotopes to allow a first chemical study of bohrium. In 1999, the team at LBNL claimed the discovery of long-lived 267Bh (5 atoms) and 266Bh (1 atom). Later, both of these were confirmed. The team at the Paul Scherrer Institute (PSI) in Bern, Switzerland later synthesized 6 atoms of 267Bh in the first definitive study of the chemistry of bohrium.

As decay products
Bohrium has been detected in the decay chains of elements with a higher atomic number, such as meitnerium. Meitnerium currently has seven known isotopes; all of them undergo alpha decays to become bohrium nuclei, with mass numbers between 262 and 274. Parent meitnerium nuclei can be themselves decay products of roentgenium, nihonium, flerovium, moscovium, livermorium, or tennessine. For example, in January 2010, the Dubna team (JINR) identified bohrium-274 as a product in the decay of tennessine via an alpha decay sequence:

Nuclear isomerism
The only confirmed example of isomerism in bohrium is in the isotope 262Bh. Direct synthesis of 262Bh results in two states, a ground state and an isomeric state. The ground state is confirmed to decay by alpha decay, emitting alpha particles with energies of 10.08, 9.82, and 9.76 MeV, and has a revised half-life of 84 ms. The excited state also decays by alpha decay, emitting alpha particles with energies of 10.37 and 10.24 MeV, and has a revised half-life of 9.6 ms.
 * 262Bh

Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing bohrium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

Hot fusion
The table below provides cross-sections and excitation energies for hot fusion reactions producing bohrium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Isotopes of bohrium


text:
Isotopes of hassium

Hassium (108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 13 known isotopes from 263Hs to 277Hs and up to six isomers. The most stable known isotope is 271Hs, with a half-life of about 46 seconds, though this assignment is not definite due to uncertainty arising from a low number of measurements. The isotopes 269Hs and 270Hs respectively have half-lives of about 12 seconds and 7.6 seconds. It is also possible that the isomer 277mHs is more stable than these, with a reported half-life $130$ seconds, but only one event of decay of this isotope has been registered as of 2016.

List of isotopes
[$2.97 ms$] [$74 ms$]
 * 263Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 155
 * 263.12848(21)#
 * 760(40) μs
 * α
 * 259Sg
 * 3/2+#
 * rowspan=2|264Hs
 * rowspan=2 style="text-align:right" | 108
 * rowspan=2 style="text-align:right" | 156
 * rowspan=2|264.12836(3)
 * rowspan=2|0.7(3) ms
 * α (70%)
 * 260Sg
 * rowspan=2|0+
 * SF (30%)
 * (various)
 * 265Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 157
 * 265.129792(26)
 * 1.96(16) ms
 * α
 * 261Sg
 * 9/2+#
 * style="text-indent:.3em" | 265mHs
 * colspan="3" style="text-indent:2em" | 229(22) keV
 * 360(150) μs
 * α
 * 261Sg
 * 3/2+#
 * rowspan=2|266Hs
 * rowspan=2 style="text-align:right" | 108
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2| 266.130049(29)
 * rowspan=2|$0.38 s$
 * α (76%)
 * 262Sg
 * rowspan=2|0+
 * SF (24%)
 * (various)
 * style="text-indent:.3em" | 266mHs
 * colspan="3" style="text-indent:2em" | 1100(70) keV
 * 280(220) ms
 * rowspan=2|0+
 * SF (24%)
 * (various)
 * style="text-indent:.3em" | 266mHs
 * colspan="3" style="text-indent:2em" | 1100(70) keV
 * 280(220) ms
 * colspan="3" style="text-indent:2em" | 1100(70) keV
 * 280(220) ms
 * α
 * 262Sg
 * 9-#
 * 267Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 159
 * 267.13168(10)#
 * 55(11) ms
 * α
 * 263Sg
 * 5/2+#
 * style="text-indent:.3em" | 267mHs
 * colspan="3" style="text-indent:2em" | 39(24) keV
 * 990(90) μs
 * α
 * 263Sg
 * 268Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 160
 * 268.13201(32)#
 * 1.42(1.13) s
 * style="text-align:right" | 108
 * style="text-align:right" | 160
 * 268.13201(32)#
 * 1.42(1.13) s
 * α
 * 264Sg
 * 0+
 * 269Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 161
 * 269.13365(14)#
 * α
 * 265Sg
 * 9/2+#
 * rowspan=2 style="text-indent:1em" | 269mHs
 * rowspan=2 colspan="3" style="text-indent:2em" | 20 keV#
 * rowspan=2|$13 s$
 * α
 * 265mSg
 * rowspan=2|1/2#
 * IT
 * 269Hs
 * rowspan=2|270Hs
 * rowspan=2 style="text-align:right" | 108
 * rowspan=2 style="text-align:right" | 162
 * rowspan=2|270.13431(27)#
 * rowspan=2|$2.8 s$
 * α
 * 266Sg
 * rowspan=2|0+
 * SF (<50%)
 * (various)
 * 271Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 163
 * 271.13708(30)#
 * α
 * 267Sg
 * 11/2#
 * rowspan=2 style="text-indent:1em" | 271mHs
 * rowspan=2 colspan="3" style="text-indent:2em" | 20 keV#
 * rowspan=2|$7.6 s$
 * α
 * 267mSg
 * rowspan=2|3/2#
 * IT
 * 271Hs
 * 272Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 164
 * 272.13849(55)#
 * α
 * 268Sg
 * 0+
 * 273Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 165
 * 273.14146(40)#
 * α
 * 269Sg
 * 3/2+#
 * rowspan=2|275Hs
 * rowspan=2 style="text-align:right" | 108
 * rowspan=2 style="text-align:right" | 167
 * rowspan=2|275.14653(64)#
 * rowspan=2|$46 s$
 * α
 * 271Sg
 * rowspan=2|
 * SF (<11%)
 * (various)
 * 277Hs
 * style="text-align:right" | 108
 * style="text-align:right" | 169
 * 277.15177(48)#
 * SF
 * (various)
 * 3/2+#
 * style="text-indent:.3em" | 277mHs
 * colspan="3" style="text-indent:2em" | 100(100) keV#
 * 130(100) s
 * SF
 * (various)
 * 278Hs
 * 108
 * 170
 * 278.15375(32)#
 * 2# s
 * SF
 * (various)
 * 0+
 * 277.15177(48)#
 * SF
 * (various)
 * 3/2+#
 * style="text-indent:.3em" | 277mHs
 * colspan="3" style="text-indent:2em" | 100(100) keV#
 * 130(100) s
 * SF
 * (various)
 * 278Hs
 * 108
 * 170
 * 278.15375(32)#
 * 2# s
 * SF
 * (various)
 * 0+
 * 2# s
 * SF
 * (various)
 * 0+

Nucleosynthesis
Superheavy elements such as hassium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of hassium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.

Depending on the energies involved, the former are separated into "hot" and "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).

Cold fusion
Before the first successful synthesis of hassium in 1984 by the GSI team, scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia also tried to synthesize hassium by bombarding lead-208 with iron-58 in 1978. No hassium atoms were identified. They repeated the experiment in 1984 and were able to detect a spontaneous fission activity assigned to 260Sg, the daughter of 264Hs. Later that year, they tried the experiment again, and tried to chemically identify the decay products of hassium to provide support to their synthesis of element 108. They were able to detect several alpha decays of 253Es and 253Fm, decay products of 265Hs.

In the official discovery of the element in 1984, the team at GSI studied the same reaction using the alpha decay genetic correlation method and were able to positively identify 3 atoms of 265Hs. After an upgrade of their facilities in 1993, the team repeated the experiment in 1994 and detected 75 atoms of 265Hs and 2 atoms of 264Hs, during the measurement of a partial excitation function for the 1n neutron evaporation channel. A further run of the reaction was conducted in late 1997 in which a further 20 atoms were detected. This discovery experiment was successfully repeated in 2002 at RIKEN (10 atoms) and in 2003 at GANIL (7 atoms). The team at RIKEN further studied the reaction in 2008 in order to conduct the first spectroscopic studies of the even-even nucleus 264Hs. They were also able to detect a further 29 atoms of 265Hs.

The team at Dubna also conducted the analogous reaction with a lead-207 target instead of a lead-208 target in 1984:

They were able to detect the same spontaneous fission activity as observed in the reaction with a lead-208 target and once again assigned it to 260Sg, daughter of 264Hs. The team at GSI first studied the reaction in 1986 using the method of genetic correlation of alpha decays and identified a single atom of 264Hs with a cross section of 3.2 pb. The reaction was repeated in 1994 and the team were able to measure both alpha decay and spontaneous fission for 264Hs. This reaction was also studied in 2008 at RIKEN in order to conduct the first spectroscopic studies of the even-even nucleus 264Hs. The team detected 11 atoms of 264Hs.

In 2008, the team at RIKEN conducted the analogous reaction with a lead-206 target for the first time:

They were able to identify 8 atoms of the new isotope 263Hs.

In 2008, the team at the Lawrence Berkeley National Laboratory (LBNL) studied the analogous reaction with iron-56 projectiles for the first time:

They were able to produce and identify six atoms of the new isotope 263Hs. A few months later, the RIKEN team also published their results on the same reaction.

Further attempts to synthesise nuclei of hassium were performed the team at Dubna in 1983 using the cold fusion reaction between a bismuth-209 target and manganese-55 projectiles:

 * + →  + x  (x = 1 or 2)

They were able to detect a spontaneous fission activity assigned to 255Rf, a product of the 263Hs decay chain. Identical results were measured in a repeat run in 1984. In a subsequent experiment in 1983, they applied the method of chemical identification of a descendant to provide support to the synthesis of hassium. They were able to detect alpha decays from fermium isotopes, assigned as descendants of the decay of 262Hs. This reaction has not been tried since and 262Hs is currently unconfirmed.

Hot fusion
Under the leadership of Yuri Oganessian, the team at the Joint Institute for Nuclear Research studied the hot fusion reaction between calcium-48 projectiles and radium-226 targets in 1978:

 * + →  + 4

However, results are not available in the literature. The reaction was repeated at the JINR in June 2008 and 4 atoms of the isotope 270Hs were detected. In January 2009, the team repeated the experiment and a further 2 atoms of 270Hs were detected.

The team at Dubna studied the reaction between californium-249 targets and neon-22 projectiles in 1983 by detecting spontaneous fission activities:

 * + →  + x

Several short spontaneous fission activities were found, indicating the formation of nuclei of hassium.

The hot fusion reaction between uranium-238 targets and projectiles of the rare and expensive isotope sulfur-36 was conducted at the GSI in April–May 2008:

 * + →  + 4

Preliminary results show that a single atom of 270Hs was detected. This experiment confirmed the decay properties of the isotopes 270Hs and 266Sg.

In March 1994, the team at Dubna led by the late Yuri Lazarev attempted the analogous reaction with sulfur-34 projectiles:

 * + →  + x  (x = 4 or 5)

They announced the detection of 3 atoms of 267Hs from the 5n neutron evaporation channel. The decay properties were confirmed by the team at GSI in their simultaneous study of darmstadtium. The reaction was repeated at the GSI in January–February 2009 in order to search for the new isotope 268Hs. The team, led by Prof. Nishio, detected a single atom each of both 268Hs and 267Hs. The new isotope 268Hs underwent alpha decay to the previously known isotope 264Sg.

Between May 2001 and August 2005, a GSI–PSI (Paul Scherrer Institute) collaboration studied the nuclear reaction between curium-248 targets and magnesium-26 projectiles:

 * + →  + x  (x = 3, 4, or 5)

The team studied the excitation function of the 3n, 4n, and 5n evaporation channels leading to the isotopes 269Hs, 270Hs, and 271Hs. The synthesis of the doubly magic isotope 270Hs was published in December 2006 by the team of scientists from the Technical University of Munich. It was reported that this isotope decayed by emission of an alpha particle with an energy of 8.83 MeV and a half-life of ~22 s. This figure has since been revised to 3.6 s.

As decay product
Hassium isotopes have been observed as decay products of darmstadtium. Darmstadtium currently has ten known isotopes, all but one of which have been shown to undergo alpha decays to become hassium nuclei with mass numbers between 263 and 277. Hassium isotopes with mass numbers 266, 272, 273, 275, and 277 to date have only been produced by decay of darmstadtium nuclei. Parent darmstadtium nuclei can be themselves decay products of copernicium, flerovium, or livermorium. For example, in 2004, the Dubna team identified hassium-277 as a final product in the decay of livermorium-293 via an alpha decay sequence:

Unconfirmed isotopes
An isotope assigned to 277Hs has been observed on one occasion decaying by SF with a long half-life of ~11 minutes. The isotope is not observed in the decay of the ground state of 281Ds but is observed in the decay from a rare, as yet unconfirmed isomeric level, namely 281mDs. The half-life is very long for the ground state and it is possible that it belongs to an isomeric level in 277Hs. It has also been suggested that this activity actually comes from 278Bh, formed as the great-great-granddaughter of 290Fl through one electron capture to 290Nh and three further alpha decays. Furthermore, in 2009, the team at the GSI observed a small alpha decay branch for 281Ds producing the nuclide 277Hs decaying by SF in a short lifetime. The measured half-life is close to the expected value for ground state isomer, 277Hs. Further research is required to confirm the production of the isomer.
 * 277mHs

Retracted isotopes
In 1999, American scientists at the University of California, Berkeley, announced that they had succeeded in synthesizing three atoms of 293118. These parent nuclei were reported to have successively emitted three alpha particles to form hassium-273 nuclei, which were claimed to have undergone an alpha decay, emitting alpha particles with decay energies of 9.78 and 9.47 MeV and half-life 1.2 s, but their claim was retracted in 2001. The isotope, however, was produced in 2010 by the same team. The new data matched the previous (fabricated) data.
 * 273Hs

270Hs: prospects for a deformed doubly magic nucleus
According to macroscopic-microscopic (MM) theory, Z = 108 is a deformed proton magic number, in combination with the neutron shell at N = 162. This means that such nuclei are permanently deformed in their ground state but have high, narrow fission barriers to further deformation and hence relatively long SF partial half-lives. The SF half-lives in this region are typically reduced by a factor of 109 in comparison with those in the vicinity of the spherical doubly magic nucleus 298Fl, caused by an increase in the probability of barrier penetration by quantum tunnelling, due to the narrower fission barrier. In addition, N = 162 has been calculated as a deformed neutron magic number and hence the nucleus 270Hs has promise as a deformed doubly magic nucleus. Experimental data from the decay of Z = 110 isotopes 271Ds and 273Ds, provides strong evidence for the magic nature of the N = 162 sub-shell. The recent synthesis of 269Hs, 270Hs, and 271Hs also fully support the assignment of N = 162 as a magic closed shell. In particular, the low decay energy for 270Hs is in complete agreement with calculations.

Evidence for the Z = 108 deformed proton shell
Evidence for the magicity of the Z = 108 proton shell can be deemed from two sources:
 * 1) the variation in the partial spontaneous fission half-lives for isotones
 * 2) the large gap in Qα for isotonic pairs between Z = 108 and Z = 110.

For SF, it is necessary to measure the half-lives for the isotonic nuclei 268Sg, 270Hs and 272Ds. Since fission of 270Hs has not been measured, detailed data of 268Sg fission is not yet available, and 272Ds is still unknown, this method cannot be used to date to confirm the stabilizing nature of the Z = 108 shell. However, good evidence for the magicity of Z = 108 can be deemed from the large differences in the alpha decay energies measured for 270Hs, 271Ds and 273Ds. More conclusive evidence would come from the determination of the decay energy of the yet-unknown nuclide 272Ds.

Nuclear isomerism
An isotope assigned to 277Hs has been observed on one occasion decaying by spontaneous fission with a long half-life of ~11 minutes. The isotope is not observed in the decay of the most common isomer of 281Ds but is observed in the decay from a rare, as yet unconfirmed isomeric level, namely 281mDs. The half-life is very long for the ground state and it is possible that it belongs to an isomeric level in 277Hs. Furthermore, in 2009, the team at the GSI observed a small alpha decay branch for 281Ds producing an isotope of 277Hs decaying by spontaneous fission with a short lifetime. The measured half-life is close to the expected value for ground state isomer, 277Hs. Further research is required to confirm the production of the isomer. A more recent study suggests that this observed activity may actually be from 278Bh.
 * 277Hs

The direct synthesis of 269Hs has resulted in the observation of three alpha particles with energies 9.21, 9.10, and 8.94 MeV emitted from 269Hs atoms. However, when this isotope is indirectly synthesized from the decay of 277Cn, only alpha particles with energy 9.21 MeV have been observed, indicating that this decay occurs from an isomeric level. Further research is required to confirm this.
 * 269Hs

267Hs is known to decay by alpha decay, emitting alpha particles with energies of 9.88, 9.83, and 9.75 MeV. It has a half-life of 52 ms. In the recent syntheses of 271Ds and 271mDs, additional activities have been observed. A 0.94 ms activity emitting alpha particles with energy 9.83 MeV has been observed in addition to longer lived ~0.8 s and ~6.0 s activities. Currently, none of these are assigned and confirmed and further research is required to positively identify them.
 * 267Hs

The synthesis of 265Hs has also provided evidence for two isomeric levels. The ground state decays by emission of an alpha particle with energy 10.30 MeV and has a half-life of 2.0 ms. The isomeric state has 300 keV of excess energy and decays by the emission of an alpha particle with energy 10.57 MeV and has a half-life of 0.75 ms.
 * 265Hs

Scientists at the GSI are planning to search for isomers of 270Hs using the reaction 226Ra(48Ca,4n) in 2010 using the new TASCA facility at the GSI. In addition, they also hope to study the spectroscopy of 269Hs, 265Sg and 261Rf, using the reaction 248Cm(26Mg,5n) or 226Ra(48Ca,5n). This will allow them to determine the level structure in 265Sg and 261Rf and attempt to give spin and parity assignments to the various proposed isomers.
 * Future experiments

Physical production yields
The tables below provides cross-sections and excitation energies for nuclear reactions that produce isotopes of hassium directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Evaporation residue cross sections
The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system ; σ = cross section

title: Isotopes of hassium


text:
Wikipedia:Articles for deletion/Aristar

 This page is an archive of the proposed deletion of the article below. Further comments should be made on the appropriate discussion page (such as the article's talk page or on a Votes for Undeletion nomination). No further edits should be made to this page.

The result of the debate was delete. Sjakkalle (Check!)  11:23, 31 August 2005 (UTC)

Aristar
Non-notable band KeithD (talk) 11:39, 24 August 2005 (UTC)

 * Delete as per nom. -- Ryan Norton T 11:44, 24 August 2005 (UTC)
 * They assert a national tour of England, which could make them meet WP:MUSIC if it were legit. However allmusic has never heard of them so I'm skeptical.  Delete unless shown to meet music guideline.  Friday (talk) 18:26, 24 August 2005 (UTC)
 * Comment. I have greeted the initial editor and pointed them here. I advised about the wiki for independent musicians - Skwik.
 * Delete nn band vanity. -- Etacar11   02:29, 25 August 2005 (UTC)
 * Delete - not notable/vanity - Tεx  τ  urε  16:32, 29 August 2005 (UTC)
 * The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in an undeletion request). No further edits should be made to this page.

title: Wikipedia:Articles for deletion/Aristar


text:
Wikipedia:Articles for deletion/David Jasper

 This page is an archive of the proposed deletion of the article below. Further comments should be made on the appropriate discussion page (such as the article's talk page or on a Votes for Undeletion nomination). No further edits should be made to this page.

The result of the debate was keep. --Tony Sidaway Talk 10:19, 30 August 2005 (UTC)

David Jasper
I could not confirm any of the given information to be true with Google. Anyone else? feydey 11:39, 24 August 2005 (UTC) Keep the updated version, good work Doc, feydey 15:08, 24 August 2005 (UTC)

 * Delete or find out notability, google turns up empty for the k corridor theory or whatever which is usually a good sign -- Ryan Norton T 11:43, 24 August 2005 (UTC)
 * Keep Updated version looks better -- Ryan Norton T 14:34, 24 August 2005 (UTC)
 * Delete per submitter. Corridor theory (sans K) seems valid, but "corridor theory" +jasper turns up nothing. --GraemeL (talk) 12:07, 24 August 2005 (UTC)
 * Keep. Thanks to Doc for taking the time to re-write the entry. --GraemeL (talk) 14:36, 24 August 2005 (UTC)

 * Strong Keep I get lots of Google hits for "David Jasper" who is quite notable in the field of Theology and Religious Studies - see e.g.  Dlyons493 13:05, 24 August 2005 (UTC)
 * The David Jasper you found may be worthy of an entry, but comparing his bio on the Glasgow University site to the article makes me doubt it's the same person. I strongly suspect a hoax. "Sir David is Married to Victoria" just screams David Beckham. Nothing in the article seems verifiable. If somebody wants to re-write the article to reference the David Jasper you found, I'll consider changing my vote. --GraemeL (talk) 13:35, 24 August 2005 (UTC)

 * Delete unless re-written . Prof Jasper (who was, incidently, one of my lecturers) is certainly a notable accademic, but this isn't him. --Doc (?) 13:58, 24 August 2005 (UTC)
 * On the basis of {so fix it}, I have, so keep --Doc (?) 14:28, 24 August 2005 (UTC)

 * Keep rewritten version--good work, Doc. Meelar (talk) 14:33, August 24, 2005 (UTC)
 * Keep Doc's rewritten version which shows he is a notable academic with plenty of books to his credit. Capitalistroadster 17:01, 24 August 2005 (UTC)
 * The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in an undeletion request). No further edits should be made to this page.


text:
Skibobbing

Skibobbing (also called skibiking or snowbiking) is a winter sport involving a bicycle-type frame attached to skis instead of wheels and sometimes a set of foot skis. The use of foot skis is what defines "skibobbing".

Although skibobs are often called ski bikes or snow bikes, they are different, and the sport should also not be confused with snowbiking, which is the sport or recreation of bicycling on snow.

Type-1 skibobs have minimal to no suspension, you sit on the seat and foot ski's are used for control.

Type-2 bikes, also known as "peggers" are similar in design to a mtn bike which usually has full suspension but utilizes the foot pegs and are generally operated standing up. Also called "freestyle" ski bikes.

Type-3 bikes, or 'Trikes' have 1 ski in the front and 2 in the back and are considered more stable and easier to ride.

History
Although the original idea for a bicycle with skis was patented as early as 1892, and skibobbing had been a form of transportation in the Alps, it was not until 1954 that the first international race was held. Seven years later, the FISB (Fédération Internationále de Skibob) was formed, which since 1967 has held an annual Skibobbing World Championship.

Originally, skibobbing was one of the very few methods by which could alpine ski, but it soon became a popular sport amongst the physically able, too. The main attractions are said to be the speeds attained (in some skibob giant slalom races, speeds of 120 mph or more can be reached) and the feeling of jet skiing on snow.

Austrian skibobber Erich Brenter is noted for setting the first world record for downhill skibobbing speed in 1964, at 102 mph.

title: Skibobbing


text:
Isotopes of meitnerium

Meitnerium (109Mt) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 266Mt in 1982, and this is also the only isotope directly synthesized; all other isotopes are only known as decay products of heavier elements. There are eight known isotopes, from 266Mt to 278Mt. There may also be two isomers. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds. The unconfirmed heavier 282Mt appears to have an even longer half-life of 67 seconds.

List of isotopes

 * 266Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 157
 * 266.137060(100)
 * α
 * 262Bh
 * style="text-indent:1em" | 266mMt
 * colspan="3" style="text-indent:2em" |1140(90) keV
 * α
 * 262Bh
 * 268Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 159
 * 268.13865(25)#
 * α
 * 264Bh
 * 5+#, 6+#
 * style="text-indent:1em" | 268mMt
 * colspan="3" style="text-indent:2em" | 0+X keV
 * α
 * 264Bh
 * 270Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 161
 * 270.14033(18)#
 * α
 * 266Bh
 * style="text-indent:1em" | 270mMt
 * colspan="3" style="text-indent:2em" |
 * 1.1 s?
 * α
 * 266Bh
 * 274Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 165
 * 274.14725(38)#
 * α
 * 270Bh
 * 275Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 166
 * 275.14882(50)#
 * α
 * 271Bh
 * 276Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 167
 * 276.15159(59)#
 * α
 * 272Bh
 * style="text-indent:1em" | 276mMt
 * colspan="3" style="text-indent:2em" |250(80) keV
 * α
 * 272Bh
 * 277Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 168
 * 277.15327(82)#
 * SF
 * (various)
 * 278Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 169
 * 278.15631(68)#
 * α
 * 274Bh
 * 282Mt
 * style="text-align:right"| 109
 * style="text-align:right"| 173
 * 67 s?
 * α
 * 278Bh
 * α
 * 272Bh
 * style="text-indent:1em" | 276mMt
 * colspan="3" style="text-indent:2em" |250(80) keV
 * α
 * 272Bh
 * 277Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 168
 * 277.15327(82)#
 * SF
 * (various)
 * 278Mt
 * style="text-align:right" | 109
 * style="text-align:right" | 169
 * 278.15631(68)#
 * α
 * 274Bh
 * 282Mt
 * style="text-align:right"| 109
 * style="text-align:right"| 173
 * 67 s?
 * α
 * 278Bh
 * α
 * 274Bh
 * 282Mt
 * style="text-align:right"| 109
 * style="text-align:right"| 173
 * 67 s?
 * α
 * 278Bh
 * 67 s?
 * α
 * 278Bh
 * 278Bh

Nucleosynthesis
Super-heavy elements such as meitnerium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas the lightest isotope of meitnerium, meitnerium-266, can be synthesized directly this way, all the heavier meitnerium isotopes have only been observed as decay products of elements with higher atomic numbers.

Depending on the energies involved, the former are separated into "hot" and "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. Nevertheless, the products of hot fusion tend to still have more neutrons overall. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z = 109.

Cold fusion
After the first successful synthesis of meitnerium in 1982 by the GSI team, a team at the Joint Institute for Nuclear Research in Dubna, Russia, also tried to observe the new element by bombarding bismuth-209 with iron-58. In 1985 they managed to identity alpha decays from the descendant isotope 246Cf indicating the formation of meitnerium. The observation of a further two atoms of 266Mt from the same reaction was reported in 1988 and of another 12 in 1997 by the German team at GSI.

The same meitnerium isotope was also observed by the Russian team at Dubna in 1985 from the reaction:

by detecting the alpha decay of the descendant 246Cf nuclei. In 2007, an American team at the Lawrence Berkeley National Laboratory (LBNL) confirmed the decay chain of the 266Mt isotope from this reaction.

Hot fusion
In 2002–2003, the team at LBNL attempted to generate the isotope 271Mt to study its chemical properties by bombarding uranium-238 with chlorine-37, but without success. Another possible reaction that would form this isotope would be the fusion of berkelium-249 with magnesium-26; however, the yield for this reaction is expected to be very low due to the high radioactivity of the berkelium-249 target. Other potentially longer-lived isotopes were unsuccessfully targeted by a team at Lawrence Livermore National Laboratory (LLNL) in 1988 by bombarding einsteinium-254 with neon-22.

Decay products
All the isotopes of meitnerium except meitnerium-266 have been detected only in the decay chains of elements with a higher atomic number, such as roentgenium. Roentgenium currently has eight known isotopes; all but one of them undergo alpha decays to become meitnerium nuclei, with mass numbers between 268 and 282. Parent roentgenium nuclei can be themselves decay products of nihonium, flerovium, moscovium, livermorium, or tennessine. For example, in January 2010, the Dubna team (JINR) identified meitnerium-278 as a product in the decay of tennessine via an alpha decay sequence:

Nuclear isomerism
Two atoms of 270Mt have been identified in the decay chains of 278Nh. The two decays have very different lifetimes and decay energies and are also produced from two apparently different isomers of 274Rg. The first isomer decays by emission of an alpha particle with energy 10.03 MeV and has a lifetime of 7.16 ms. The other alpha decays with a lifetime of 1.63 s; the decay energy was not measured. An assignment to specific levels is not possible with the limited data available and further research is required.
 * 270Mt

The alpha decay spectrum for 268Mt appears to be complicated from the results of several experiments. Alpha particles of energies 10.28, 10.22 and 10.10 MeV have been observed, emitted from 268Mt atoms with half-lives of 42 ms, 21 ms and 102 ms respectively. The long-lived decay must be assigned to an isomeric level. The discrepancy between the other two half-lives has yet to be resolved. An assignment to specific levels is not possible with the data available and further research is required.
 * 268Mt

Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing meitnerium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Evaporation residue cross sections
The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; HIVAP = heavy-ion vaporisation statistical-evaporation model; σ = cross section

title: Isotopes of meitnerium


text:
Isotopes of darmstadtium

Darmstadtium (110Ds) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 269Ds in 1994. There are 11 known radioisotopes from 267Ds to 281Ds (with many gaps) and 2 or 3 known isomers. The longest-lived isotope is 281Ds with a half-life of 14 seconds. However, the unconfirmed 282Ds might have an even longer half-life of 67 seconds.

List of isotopes
[$2.8 μs$] [$170 μs$] [$205 μs$] [$4.3 ms$] [$3.9 ms$] [$1.63 ms$] [$190 μs$] [$430 μs$]
 * 267Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 157
 * 267.14373(22)#
 * 10(8) μs
 * 10(8) μs
 * α
 * 263Hs
 * 3/2+#
 * 269Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 159
 * 269.14475(3)
 * 230(110) μs
 * 230(110) μs
 * α
 * 265Hs
 * 270Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 160
 * 270.14459(4)
 * α
 * 266Hs
 * 0+
 * rowspan=2 style="text-indent:1em" | 270mDs
 * rowspan=2 colspan="3" style="text-indent:2em" | 1390(60) keV
 * rowspan=2|$150 us$
 * rowspan=2 style="text-indent:1em" | 270mDs
 * rowspan=2 colspan="3" style="text-indent:2em" | 1390(60) keV
 * rowspan=2|$6 ms$
 * rowspan=2|$4.1 ms$
 * α (70%)
 * 266Hs
 * rowspan=2|10−#
 * IT (30%)
 * 270Ds
 * rowspan=2|271Ds
 * rowspan=2 style="text-align:right" | 110
 * rowspan=2 style="text-align:right" | 161
 * rowspan=2|271.14595(10)#
 * rowspan=2|144(53) ms
 * SF (75%)
 * (various)
 * rowspan=2|
 * α (25%)
 * 267Hs
 * style="text-indent:1em" | 271mDs
 * colspan="3" style="text-indent:2em" | 68(27) keV
 * 1.7(4) ms
 * style="text-indent:1em" | 271mDs
 * colspan="3" style="text-indent:2em" | 68(27) keV
 * 1.7(4) ms
 * 1.7(4) ms
 * α
 * 267Hs
 * 273Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 163
 * 273.14846(15)#
 * 240(100) μs
 * 273.14846(15)#
 * 240(100) μs
 * α
 * 269Hs
 * style="text-indent:1em" | 273mDs
 * colspan="3" style="text-indent:2em" | 198(20) keV
 * 120 ms
 * α
 * 269Hs
 * 275Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 165
 * 275.15209(37)#
 * α
 * 271Hs
 * 3/2#
 * rowspan=2|276Ds
 * rowspan=2 style="text-align:right" | 110
 * rowspan=2 style="text-align:right" | 166
 * rowspan=2|276.15302(59)#
 * rowspan=2|$186 ms$
 * SF (57%)
 * (various)
 * rowspan=2|0+
 * α (43%)
 * 272Hs
 * 277Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 167
 * 277.15576(42)#
 * α (43%)
 * 272Hs
 * 277Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 167
 * 277.15576(42)#
 * style="text-align:right" | 167
 * 277.15576(42)#
 * α
 * 273Hs
 * rowspan=2|279Ds
 * rowspan=2 style="text-align:right" | 110
 * rowspan=2 style="text-align:right" | 169
 * rowspan=2|279.15998(65)#
 * rowspan=2|$360 μs$
 * SF (87%)
 * (various)
 * rowspan=2|
 * α (13%)
 * 275Hs
 * 280Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 170
 * 280.16138(80)#
 * SF
 * (various)
 * 0+
 * rowspan=2|281Ds
 * rowspan=2 style="text-align:right" | 110
 * rowspan=2 style="text-align:right" | 171
 * rowspan=2|281.16455(53)#
 * rowspan=2|14(3) s
 * SF (90%)
 * (various)
 * rowspan=2|
 * α (10%)
 * 277Hs
 * style="text-indent:1em" | 281mDs
 * colspan="3" style="text-indent:2em" | 80(240)# keV
 * 0.9(7) ms
 * rowspan=2|
 * α (10%)
 * 277Hs
 * style="text-indent:1em" | 281mDs
 * colspan="3" style="text-indent:2em" | 80(240)# keV
 * 0.9(7) ms
 * colspan="3" style="text-indent:2em" | 80(240)# keV
 * 0.9(7) ms
 * α
 * 277Hs
 * 282Ds
 * style="text-align:right" | 110
 * style="text-align:right" | 172
 * 282.16617(32)#
 * 4.2(3.3) min
 * 282.16617(32)#
 * 4.2(3.3) min
 * α
 * 278Hs
 * 0+

Nucleosynthesis
Superheavy elements such as darmstadtium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of darmstadtium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.

Depending on the energies involved, the former are separated into "hot" and "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z = 110.

Cold fusion
Before the first successful synthesis of darmstadtium in 1994 by the GSI team, scientists at GSI also tried to synthesize darmstadtium by bombarding lead-208 with nickel-64 in 1985. No darmstadtium atoms were identified. After an upgrade of their facilities, the team at GSI successfully detected 9 atoms of 271Ds in two runs of their discovery experiment in 1994. This reaction was successfully repeated in 2000 by GSI (4 atoms), in 2000 and 2004 by the Lawrence Berkeley National Laboratory (LBNL) (9 atoms in total) and in 2002 by RIKEN (14 atoms). The GSI team studied the analogous reaction with nickel-62 instead of nickel-64 in 1994 as part of their discovery experiment. Three atoms of 269Ds were detected. A fourth decay chain was measured but was subsequently retracted.

In addition to the official discovery reactions, in October–November 2000, the team at GSI also studied the analogous reaction using a lead-207 target in order to synthesize the new isotope 270Ds. They succeeded in synthesising eight atoms of 270Ds, relating to a ground state isomer, 270Ds, and a high-spin metastable state, 270mDs.

In 1986, a team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, studied the reaction:

 * $0.25 s$Bi + $67 s$Co → $209 83$Ds + $59 27$n

They were unable to detect any darmstadtium atoms. In 1995, the team at LBNL reported that they had succeeded in detecting a single atom of 267Ds using this reaction. However, several decays were not measured and further research is required to confirm this discovery.

Hot fusion
In the late 1980s, the GSI team attempted to synthesize element 110 by bombarding a target consisting of various uranium isotopes—233U, 235U, and 238U—with accelerated argon-40 ions. No atoms were detected; a limiting cross section of 21 pb was reported.

In September 1994, the team at Dubna detected a single atom of 273Ds by bombarding a plutonium-244 target with accelerated sulfur-34 ions.

Experiments were done in 2004 at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna studying the fission characteristics of the compound nucleus 280Ds, produced in the reaction:

 * $267 110$Th + $1 0$Ca → $232 90$Ds* → fission

The result revealed how compound nuclei such as this fission predominantly by expelling magic and doubly magic nuclei such as 132Sn (Z = 50, N = 82). No darmstadtium atoms were obtained. A compound nucleus is a loose combination of nucleons that have not arranged themselves into nuclear shells yet. It has no internal structure and is held together only by the collision forces between the target and projectile nuclei. It is estimated that it requires around 10−14 s for the nucleons to arrange themselves into nuclear shells, at which point the compound nucleus becomes a nuclide, and this number is used by IUPAC as the minimum half-life a claimed isotope must have in order to be recognized as being discovered.

The 232Th+48Ca reaction was attempted again at the FLNR in 2022; it was predicted that the 48Ca-induced reaction leading to element 110 would have a lower yield than those leading to lighter or heavier elements. Seven atoms of 276Ds were reported, with lifetimes ranging between $48 20$ and $280 110$; four decayed by spontaneous fission and three decayed via a two-alpha sequence to 272Hs and the spontaneously fissioning 268Sg. The maximum reported cross section for the production of 276Ds was about 0.7 pb and a sensitivity limit an order of magnitude lower was reached. This reported cross section is lower than that of all reactions using 48Ca as a projectile, with the exception of 249Cf + 48Ca, and it further supports the existence of magic numbers at Z = 108, N = 162 and Z = 114, N = 184. In 2023, the JINR team repeated this reaction at a higher beam energy and also found 275Ds. They intend to further study the reaction to search for 274Ds. The FLNR also successfully synthesised 273Ds in the 238U+40Ar reaction.

As decay product
Darmstadtium has been observed as a decay product of copernicium. Copernicium currently has seven known isotopes, four of which have been shown to alpha decay into darmstadtium, with mass numbers 273, 277, and 279–281. To date, all of these bar 273Ds have only been produced by decay of copernicium. Parent copernicium nuclei can be themselves decay products of flerovium or livermorium. Darmstadtium may also have been produced in the electron capture decay of roentgenium nuclei which are themselves daughters of nihonium and moscovium. For example, in 2004, the Dubna team (JINR) identified darmstadtium-281 as a product in the decay of livermorium via an alpha decay sequence:

Retracted isotopes
The first synthesis of element 114 resulted in two atoms assigned to 288Fl, decaying to the 280Ds, which underwent spontaneous fission. The assignment was later changed to 289Fl and the darmstadtium isotope to 281Ds. Hence, 280Ds remained unknown until 2016, when it was populated by the hitherto unknown alpha decay of 284Cn (previously, that nucleus was only known to undergo spontaneous fission). The discovery of 280Ds in this decay chain was confirmed in 2021; it undergoes spontaneous fission with a half-life of 360 μs.
 * 280Ds

In the claimed synthesis of 293Og in 1999, the isotope 277Ds was identified as decaying by 10.18 MeV alpha emission with a half-life of 3.0 ms. This claim was retracted in 2001. This isotope was finally created in 2010 and its decay data supported the fabrication of previous data.
 * 277Ds

In the synthesis of 277Cn in 1996 by GSI (see copernicium), one decay chain proceeded via 273Ds, which decayed by emission of a 9.73 MeV alpha particle with a lifetime of 170 ms. This would have been assigned to an isomeric level. This data could not be confirmed and thus this isotope is currently unknown or unconfirmed.
 * 273mDs

In the first attempt to synthesize darmstadtium, a 10 ms SF activity was assigned to 272Ds in the reaction 232Th(44Ca,4n). Given current understanding regarding stability, this isotope has been retracted from the table of isotopes.
 * 272Ds

Nuclear isomerism
The production of 281Ds by the decay of 289Fl or 293Lv has produced two very different decay modes. The most common and readily confirmed mode is spontaneous fission with a half-life of 11 s. A much rarer and as yet unconfirmed mode is alpha decay by emission of an alpha particle with energy 8.77 MeV with an observed half-life of around 3.7 min. This decay is associated with a unique decay pathway from the parent nuclides and must be assigned to an isomeric level. The half-life suggests that it must be assigned to an isomeric state but further research is required to confirm these reports. It was suggested in 2016 that this unknown activity might be due to 282Mt, the great-granddaughter of 290Fl via electron capture and two consecutive alpha decays.
 * 281Ds

Decay data from the direct synthesis of 271Ds clearly indicates the presence of two nuclear isomers. The first emits alpha particles with energies 10.74 and 10.69 MeV and has a half-life of 1.63 ms. The other only emits alpha particles with an energy of 10.71 MeV and has a half-life of 69 ms. The first has been assigned to the ground state and the latter to an isomeric level. It has been suggested that the closeness of the alpha decay energies indicates that the isomeric level may decay primarily by delayed isomeric transition to the ground state, resulting in an identical measured alpha energy and a combined half-life for the two processes.
 * 271Ds

The direct production of 270Ds has clearly identified two nuclear isomers. The ground state decays by alpha emission into the ground state of 266Hs by emitting an alpha particle with energy 11.03 MeV and has a half-life of 0.10 ms. The metastable state decays by alpha emission, emitting alpha particles with energies of 12.15, 11.15, and 10.95 MeV, and has a half-life of 6 ms. When the metastable state emits an alpha particle of energy 12.15 MeV, it decays into the ground state of 266Hs, indicating that it has 1.12 MeV of excess energy.
 * 270Ds

Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing darmstadtium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Fission of compound nuclei with Z = 110
Experiments have been performed in 2004 at the Flerov Laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nucleus 280Ds. The nuclear reaction used is 232Th+48Ca. The result revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as 132Sn (Z = 50, N = 82).

Decay characteristics
Theoretical calculation in a quantum tunneling model reproduces the experimental alpha decay half-live data. It also predicts that the isotope 294Ds would have alpha decay half-life of the order of 311 years.

Evaporation residue cross sections
The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; σ = cross section

title: Isotopes of darmstadtium


text:
Erskine (disambiguation)

Erskine is a town in Scotland.

Erskine may also refer to:

Australia

 * Erskine, South Australia
 * Erskine, Western Australia
 * Erskine Island, Queensland
 * Erskine Valley, Lord Howe Island, New South Wales
 * Erskine Park, New South Wales
 * Erskineville, New South Wales

United States

 * Erskine, Minnesota
 * Erskine, Oregon
 * Erskine, West Virginia

Elsewhere

 * Erskine, Alberta, Canada
 * Mount Erskine, Penang, Malaysia

People

 * Erskine (surname), including a list of people with the surname
 * Clan Erskine, a Lowland Scottish clan
 * Erskine Bowles (born 1945), American businessman and politician, chief of staff for President Clinton and co-author of the Simpson-Bowles Plan
 * Erskine B. Ingram (1866–1954), American businessman and philanthropist
 * E. Bronson Ingram II (1931–1995), American billionaire businessman and philanthropist
 * Erskine Caldwell (1903–1987), American author
 * Erskine Childers (author), 1870–1922, English-born novelist and Irish Republican
 * Erskine Hamilton Childers (1905–1974), fourth President of Ireland and Fianna Fáil minister
 * Erskine Hawkins (1914–1993), jazz trumpeter and big band leader, known for composing "Tuxedo Junction"
 * Erskine May, 1st Baron Farnborough (1815–1886), British constitutional theorist
 * Erskine Mayer (1889–1957), American major league baseball player
 * Erskine Ramsay (1864–1953), Alabama industrialist who opened savings accounts for parents who named their sons "Erskine"

Fictional people

 * Dr. Abraham Erskine, in comics from Marvel Comics, the scientist responsible for the creation of Captain America
 * Inspector Lewis Erskine, portrayed by Efrem Zimbalist, Jr. on the American TV series The F.B.I.
 * Harry Erskine, a psychic played by Tony Curtis in the 1978 movie The Manitou
 * Erskine Ravel, a character in the Skulduggery Pleasant series by Derek Landy

Other uses

 * Erskine (automobile), a brand (marque) of automobile produced by the Studebaker Corporation from 1927 to 1930
 * Erskine College, South Carolina
 * Erskine Theological Seminary, South Carolina
 * Erskine Records, a British record label founded by Harry Styles
 * Erskine (charity), provides care for military veterans in Erskine, Scotland
 * Erskine May: Parliamentary Practice, rulebook on UK parliamentary procedure

title: Erskine (disambiguation)


text:
Isotopes of roentgenium

Roentgenium (111Rg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of heavier elements. There are seven known radioisotopes, having mass numbers of 272, 274, and 278–282. The longest-lived isotope is 282Rg with a half-life of about 2 minutes, although the unconfirmed 283Rg and 286Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.

List of isotopes

 * 272Rg
 * 111
 * 161
 * 272.15327(25)#
 * α
 * 268Mt
 * 5+#, 6+#
 * 274Rg
 * 111
 * 163
 * 274.15525(19)#
 * α
 * 270Mt
 * 278Rg
 * 111
 * 167
 * 278.16149(38)#
 * α
 * 274Mt
 * rowspan=2|279Rg
 * rowspan=2|111
 * rowspan=2|168
 * rowspan=2|279.16272(51)#
 * rowspan=2|$4.2 ms$
 * α (87%)
 * 275Mt
 * SF (13%)
 * (various)
 * rowspan=2|280Rg
 * rowspan=2|111
 * rowspan=2|169
 * rowspan=2|280.16514(61)#
 * rowspan=2|$20 ms$
 * α (87%)
 * 276Mt
 * EC (13%)
 * 280Ds
 * rowspan=2 |281Rg
 * rowspan=2 |111
 * rowspan=2 |170
 * rowspan=2 |281.16636(89)#
 * rowspan=2 |$4.6 ms$
 * SF (86%)
 * (various)
 * rowspan=2|
 * α (14%)
 * 277Mt
 * 282Rg
 * 111
 * 171
 * 282.16912(72)#
 * α
 * 278Mt
 * 283Rg
 * 111
 * 172
 * 283.17054(79)#
 * 5.1 min?
 * SF
 * (various)
 * 286Rg
 * 111
 * 175
 * 10.7 min?
 * α
 * 282Mt
 * 111
 * 171
 * 282.16912(72)#
 * α
 * 278Mt
 * 283Rg
 * 111
 * 172
 * 283.17054(79)#
 * 5.1 min?
 * SF
 * (various)
 * 286Rg
 * 111
 * 175
 * 10.7 min?
 * α
 * 282Mt
 * 111
 * 175
 * 10.7 min?
 * α
 * 282Mt
 * 282Mt

Nucleosynthesis
Super-heavy elements such as roentgenium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas the lightest isotope of roentgenium, roentgenium-272, can be synthesized directly this way, all the heavier roentgenium isotopes have only been observed as decay products of elements with higher atomic numbers.

Depending on the energies involved, fusion reactions can be categorized as "hot" or "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=111.

Cold fusion
Before the first successful synthesis of roentgenium in 1994 by the GSI team, a team at the Joint Institute for Nuclear Research in Dubna, Russia, also tried to synthesize roentgenium by bombarding bismuth-209 with nickel-64 in 1986. No roentgenium atoms were identified. After an upgrade of their facilities, the team at GSI successfully detected 3 atoms of 272Rg in their discovery experiment. A further 3 atoms were synthesized in 2002. The discovery of roentgenium was confirmed in 2003 when a team at RIKEN measured the decays of 14 atoms of 272Rg.

The same roentgenium isotope was also observed by an American team at the Lawrence Berkeley National Laboratory (LBNL) from the reaction:

This reaction was conducted as part of their study of projectiles with odd atomic number in cold fusion reactions.

The 205Tl(70Zn,n)274Rg reaction was tried by the RIKEN team in 2004 and repeated in 2010 in an attempt to secure the discovery of its parent 278Nh:

Due to the weakness of the thallium target, they were unable to detect any atoms of 274Rg.

As decay product
All the isotopes of roentgenium except roentgenium-272 have been detected only in the decay chains of elements with a higher atomic number, such as nihonium. Nihonium currently has six known isotopes, with two more unconfirmed; all of them undergo alpha decays to become roentgenium nuclei, with mass numbers between 274 and 286. Parent nihonium nuclei can be themselves decay products of moscovium and tennessine, and (via unconfirmed branches) flerovium and livermorium. For example, in January 2010, the Dubna team (JINR) identified roentgenium-281 as a final product in the decay of tennessine via an alpha decay sequence:

Nuclear isomerism
Two atoms of 274Rg have been observed in the decay chain of 278Nh. They decay by alpha emission, emitting alpha particles with different energies, and have different lifetimes. In addition, the two entire decay chains appear to be different. This suggests the presence of two nuclear isomers but further research is required.
 * 274Rg

Four alpha particles emitted from 272Rg with energies of 11.37, 11.03, 10.82, and 10.40 MeV have been detected. The GSI measured 272Rg to have a half-life of 1.6 ms while recent data from RIKEN have given a half-life of 3.8 ms. The conflicting data may be due to nuclear isomers but the current data are insufficient to come to any firm assignments.
 * 272Rg

Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing roentgenium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Evaporation residue cross sections
The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; σ = cross section

title: Isotopes of roentgenium


text:
Schofields, New South Wales

Schofields is a suburb on the fringe of Sydney's urban sprawl, in the state of New South Wales, Australia. Schofields is located 45 km north-west of the Sydney central business district, in the Blacktown local government area. It is part of Greater Western Sydney's North West Growth Area.

Demographics
As at the 2016 Census, Schofields had an estimated population of 4,983. In 2001, Schofields had an estimated population of 3,012. Over the 15-year period, Schofield's population increased by 65.4%. The suburb is on the rural-urban fringe of Sydney, and is expanding rapidly. It is in the NSW Government's North West Growth Area. Schofields has numerous housing developments underway, which are expected to provide over 2,950 new homes.

The most common religion in Schofields is Catholicism (30.8%). The second largest religion is No Religion (17.7%). The most spoken language in Schofields is English, with Hindi being the second most spoken language at 3.7%. The majority of people from Schofields identified as Australian (21.3%), followed closely by English (20.4%). The third largest ancestry was Indian at 8.4%.

Early history of Schofields
John Schofield (1803–1884) was transported from England to the Colony of New South Wales for stealing when he was just 17 years old. At the time he was a silk weaver from Cheshire. He was transported aboard HMS Minerva (1820) in 1821 and was assigned to work for Thomas Harley, a free-settler, on his farm at. In 1828, Schofield was granted a Ticket of Leave, which allowed him to live freely within the district of Parramatta. In 1829, he married Bridget Harley, the daughter of his former employer. Schofield then rented Gillingham Farm, located near the Eastern Creek.

The Schofields delivered eight offspring; five males and three females. In 1841, Schofield bought three 0.25 acre blocks of land along the Windsor Road. Unfortunately, due to falling wool prices and a general state of depression in the colony, Schofield became bankrupt in 1843. New government concessions introduced a few years later allowed Schofield to buy 600 acre of land around the area now known as Schofields in 1845. In 1849, Schofield and two of his sons, William and Samuel, sailed to California in the hope of finding gold. He returned in 1850 with some gold, but their ship, the Rosetta Joseph struck land and became ship wrecked. Aboard life-boats and in very rough seas, the passengers were rescued at after ten days. Schofield and his sons returned to their farm with enough gold to pay off most of his debts. Just before Christmas in 1851, Bridget Schofield died. The discovery of gold in New South Wales and a rise in the economy provided Schofield with enough money to pay off his mortgage and develop his keen interest in horseracing.

The railway line from to  opened in 1864 and passed through Schofield's land. In 1872, a stopping place was recognised on Schofield's land and a small platform made from railway sleepers was built after that to make boarding the train safer. This platform was known as Schofield's Siding. The name changed over the years to Schofields.

In his later life, Schofield set up a sawmill beside the railway line and used the trees from his paddocks in Schofields to supply timber for housing. John Schofield died in 1884.

Modern history
The suburb boundaries of Schofields were changed in November 2020, resulting in the creation of new suburbs of Nirimba Fields and Tallawong in the south and northeast respectively.

Parks, recreation and essential services
Schofields Park, on Station Street, is the home of the Riverstone Schofields Junior Soccer Football Club and Schofields Cricket Club.

The village also has a Community Hall that can be hired out for parties and is also regularly used by the local Church Group on Sunday mornings.

The village also has a NSW Rural Fire Service brigade, known as Schofields Bush Fire Brigade. They regularly attend house fires, car accidents, bush fires and most other emergencies in the area that require fire brigade attendance. A Woolworths Supermarket opened up across the road from the new Schofields railway station. Schofields Village Shopping Centre was completed in mid 2021 also across the road from the train station will include a Coles Supermarket and speciality stores.

The suburb was also home to the former Schofields Aerodrome and HMAS Nirimba and is now the suburb of Nirimba Fields.

Transport
Schofields railway station is on the Richmond branch.

The Westlink M7 and M2 Hills Motorway provide easy road access from both the south and the east.

Busways provide commuter bus services to/from the suburb.

Places of worship
In 1929, a hall located on St Albans Road was bought and opened as St Peter's Anglican Church the following year. Despite initial growth, St Peter's saw a decline in church attendance in the early 1970s. This decline could not be corrected and St Peter's closed in the 1980s and has now been demolished for housing development.

Schofields has a number places of worship that are currently active:

 * Lankarama Buddhist Vihara (Sri Lankan Buddhist Temple) is located on Oak Street.

 * Hope Church Sydney (Romanian Pentecostal Church) is located on Carnarvon Road.

 * SMVS Swaminarayan Mandir Sydney (Hindu Temple) is located on Grange Ave.
 * Schofields Church (Seventh Day Adventist Reform Movement) is located on Grange Ave.

title: Schofields, New South Wales


text:
Wilhelm Normann

Wilhelm Normann (16 January 1870, in Petershagen – 1 May 1939, in Chemnitz) (sometimes also spelled Norman) was a German chemist who introduced the hydrogenation of fats in 1901. This invention, protected by German patent 141,029 in 1902, had a profound influence on the production of margarine and vegetable shortening.

Early life and education
His father, Julius Normann, was the principal of the elementary school and Selekta in Petershagen. His mother was Luise Normann, née Siveke.

Normann attended primary school from 31 March 1877. At Easter of his sixth grade he moved to the Friedrichs Gymnasium in Herford. After his father applied for a teacher's job at the municipal secondary school in Kreuznach, Wilhelm changed to the Royal Secondary School in Kreuznach. He passed his examinations and left school at the age of 18.

Career
Normann began work at the Herford machine fat and oil factory Leprince & Siveke in 1888. The founder of that company was his uncle, Wilhelm Siveke. After running a branch of the company in Hamburg for two years, he started studying chemistry at the laboratory of Professor Carl Remigius Fresenius in Wiesbaden. From April 1892 Normann continued his studies at the department of oil analytics at the Berlin Institute of Technology under the supervision of Professor D. Holde. From 1895 to 1900 he studied chemistry under supervision of Prof. Claus and Prof. Willgerod and geology under supervision of Prof. Steinmann at the Albert Ludwigs University of Freiburg. There he received his doctorate in 1900 with a work about Beiträge zur Kenntnis der Reaktion zwischen unterchlorigsauren Salzen und primären aromatischen Aminen ("Contributions to the knowledge of the reactions of hypochlorite salts and primary aromatic amines"). In 1901 Normann was appointed as correspondent of the Federal Geological Institute.

Primary work
From 1901 to 1909 he was head of the laboratory at Leprince & Siveke, where conducted investigations of the properties of fats and oils.

In 1901 Normann heard about Paul Sabatier publishing an article, in which Sabatier stated that only with vaporizable organic compounds it is possible to bind catalytic hydrogen to fluid tar oils. Normann investigated and disproved Sabatier's assertion. He was able to transform liquid oleic acid into solid stearic acid by the use of catalytic hydrogenation with dispersed nickel. This was the precursor of saturated fat hardening.

On 27 February 1901 Normann invented what he called fat hardening, which was the process of producing saturated fats. On 14 August 1902 the German Imperial patent office granted patent 141,029 to the Leprince & Siveke Company, and on 21 January 1903 Normann was granted the British patent,.

During the years 1905 to 1910 Normann built a fat hardening facility in the Herford company. In 1908 the patent was bought by Joseph Crosfield & Sons Limited of Warrington, England. From the autumn of 1909 hardened fat was being successfully produced in what in a large scale plant in Warrington. The initial year's production was nearly 3000 t. When Lever Brothers produced a rival process Crosfield took them to court over patent infringement, which Crosfield lost.

From 1911 to 1922, Normann was scientific director of Ölwerke Germania (Germania Oil Factory) in Emmerich am Rhein, which was established by the Dutch Jürgens company.

From 1917, Normann built a fat hardening factory in Antwerp for the margarine company SAPA Societe anonyme des grasses, huiles et produits africaines, which operated in India. He served as technical director by order of the Belgian Colonial Society.

On 25 April 1920 he filed for German patent 407180 Verfahren zur Herstellung von gemischten Glyceriden (Procedure for the production of mixed glycerides), which was approved on 9 December 1924.

On 26 June 1920 the Firma Oelwerke Germania and Dr Wilhelm Normann filed for German patent 417215, Verfahren zur Umesterung von Fettsaurestern. (Procedure for the transesterification of fatty esters), which was approved on 27 September 1925.

From 1924 to 1927 Normann was a consultant for fat hardening facilities for foreign companies.

On 30 October 1926 Normann and the Volkmar Haenig & Comp, Metallochemische Werk Rodlebe company filed for German patent 564894, for Elektrisch beheizter Etagenroester (Electrically heated esters), approved 24 November 1932.

On 14 May 1929 he applied for German patent 582266, Verfahren zur Darstellung von Estern (Procedure for the representation of esters), which was approved on 11 August 1933.

Personal life
Normann married Martha Uflerbäumer of Herford on 12 September 1916.

On 1 January 1939 Normann retired, and he died on 1 May 1939 after an illness in the Küchwald Hospital in Chemnitz. He was entombed on 5 May 1939 in the family grave at the old cemetery on Hermannstrasse in Herford.

Awards

 * 8 June 1922: Award of the Liebig Medal by the German Chemical Society.
 * February 1939: awarded an honorary doctorate of natural sciences by the Faculty of Natural Sciences and the senate of the University of Münster in Westfalen.
 * 1939: awarded honorary membership in the Deutsche Gesellschaft für Fettforschung (DGF; German Society for Fat Research), today Deutsche Gesellschaft für Fettwissenschaft (German Society for Fat Science), Münster.

In commemoration of the inventor of fat hardening the DGF donated the Wilhelm Normann Medal on 15 May 1940. Since 1940 it has been irregularly awarded.

The Wilhelm-Normann-Berufskolleg (Wilhelm Normann Professional College) in Herford was named after Normann.

title: Wilhelm Normann


text:
Society for Cinema and Media Studies

The Society for Cinema and Media Studies (formerly the Society for Cinema Studies) is an organization of professors and scholars. Its home office is at the University of Oklahoma, but it has members throughout the world.

SCMS holds an annual conference and publishes the Journal of Cinema and Media Studies (formerly Cinema Journal), a periodical featuring articles on media from a critical (i.e., not empirical) perspective. This includes, but is not limited to, film studies, television studies, media studies, visual arts, cultural studies, film and media history, and moving image studies.

Its stated goals are:

"The Society for Cinema and Media Studies is the leading scholarly organization in the United States dedicated to promoting a broad understanding of film, television, and related media through research and teaching grounded in the contemporary humanities tradition."

Along with the University Film and Video Association, it is one of the principal academic organizations for studying media.

History
SCMS was founded in 1959 as the Society of Cinematologists. It became the Society for Cinema Studies in 1969.

It added "media" to its name in 2002 to account for the work of its members outside of the film studies discipline.

Conference locations

 * 2024 Boston
 * 2023 Denver
 * 2022 online-only
 * 2021 planned as an online-only conference
 * 2020 Denver (canceled due to the COVID-19 pandemic)
 * 2019 Seattle
 * 2018 Toronto
 * 2017 Chicago
 * 2016 Atlanta
 * 2015 Montreal
 * 2014 Seattle
 * 2013 Chicago
 * 2012 Boston
 * 2011 New Orleans
 * 2010 Los Angeles
 * 2009 Tokyo (canceled due to concerns about containing the H1N1 ["Swine Flu"] virus)
 * 2008 Philadelphia
 * 2007 Chicago
 * 2006 Vancouver
 * 2005 London
 * 2004 Atlanta
 * 2003 Minneapolis
 * 2002 Denver
 * 2001 Washington, DC
 * 2000 Chicago
 * 1999 West Palm Beach
 * 1998 San Diego (La Jolla)
 * 1997 Ottawa

title: Society for Cinema and Media Studies


text:
Christophe Rochus

Christophe Rochus (born 15 December 1978) is a retired professional male tennis player from Belgium.

Rochus is the older brother of Olivier Rochus. He reached the semi-finals of the Hamburg Masters in 2005 and was runner-up in two ATP tournaments, Valencia and Rotterdam. Rochus' career-high singles ranking was world No. 38, achieved in May 2006.

title: Christophe Rochus


text: Category:German sport shooters

title: Category:German sport shooters


text:
Talk:Corroboree frog

Isn't p. corroboree also found in Victoria (Mt Buller?)Lizby 11:43, 24 August 2005 (UTC)
 * Both corroboree frogs are only found in NSW and ACT. You may be thinking of the Baw Baw Frog, another endangered alpine species which is only found in VIC.--Tnarg 12345 09:49, 30 May 2006 (UTC)

Improvement Drive
Frog has been nominated to be improved by WP:IDRIVE. Help us improve it and support Frog with your vote on WP:IDRIVE. --Fenice 07:54, 2 January 2006 (UTC) i thought that the southern was endangered and the northern was only vunerable, is that true? —Preceding unsigned comment added by 58.169.14.47 (talk) 01:25, 11 May 2008 (UTC)

Split
This should be split into separate articles for the two species. Hesperian 04:42, 21 May 2008 (UTC)

 * Oppose - closely related enough for one article.--Kudpung (talk) 19:01, 4 August 2010 (UTC)
 * Support - We have seperate articles for both species of Dwarf Siren even though they are similar enough for individual articles. TheDarkMaster2 (talk) 19:45, 27 May 2019 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified 4 external links on Corroboree frog. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20061221183052/http://www.kidcyber.com.au/topics/frog_corrob2.htm to http://www.kidcyber.com.au/topics/frog_corrob2.htm
 * Added archive https://web.archive.org/web/20060904165852/http://www.cap.nsw.edu.au/collies_clicks/fauna/CorroboreeFrog/corroboree_frog.htm to http://www.cap.nsw.edu.au/collies_clicks/fauna/CorroboreeFrog/corroboree_frog.htm
 * Added tag to http://environment.act.gov.au/Files/actionsplans6.pdf
 * Added archive https://web.archive.org/web/20060428201303/http://www.nationalparks.nsw.gov.au/PDFs/approved_Southern_Corroboree_Frog.pdf to http://www.nationalparks.nsw.gov.au/PDFs/approved_Southern_Corroboree_Frog.pdf
 * Added archive https://web.archive.org/web/20060428201538/http://www.nationalparks.nsw.gov.au/PDFs/tsprofile_southern_corroboree_frog.pdf to http://www.nationalparks.nsw.gov.au/pdfs/tsprofile_southern_corroboree_frog.pdf

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Cheers.— InternetArchiveBot  (Report bug) 10:21, 13 August 2017 (UTC)

Proposed split?
This was brought up 12 years ago but merits a heftier discussion. I propose splitting this page into two, one for each species of corroboree frog: Southern corroboree frog and Northern corroboree frog. I don't have an optinion on whether this page (corroboree frog) should be turned into a redirect or maintained as an article (maybe worth doing if the corroboree frogs are a monophyletic group?). Comments welcome! —Collint c 19:50, 1 November 2020 (UTC)
 * Support - Due to differing statuses and conservation efforts for each species. Happily888 (talk) 04:05, 28 January 2022 (UTC)
 * Support -- There is enough information to split it into two articles and they have different conservation efforts. Gusfriend (talk) 07:42, 5 February 2022 (UTC)
 * Support - split as per reasons above and consistency of form with other TOL articles where all smaller stubs are acceptable. Loopy30 (talk) 11:50, 1 March 2022 (UTC)
 * Support- no time to do it myself right now though, so have just added a redirect for the southern one so at least people can find their way here. Laterthanyouthink (talk) 06:54, 25 March 2022 (UTC)
 * Support - I can do this in a bit Cas Liber (talk · contribs) 08:33, 25 March 2022 (UTC)

 * update - have started stubs but 1am here and I need to sleep. more tomorow Cas Liber (talk · contribs) 14:05, 25 March 2022 (UTC)

title: Talk:Corroboree frog


text: Category:Sport shooters by nationality

title: Category:Sport shooters by nationality