MARRYING THE "BUSH SPIRITS-PARENTS" PERSONAL DESTINY AND DIVINATION AMONG THE SÈMÈ OF BURKINA FASO ANNE FOURNIER INTRODUCTION: THE BUSH SPIRIT WHO COMES TO LIVE AT HOME

In a number of societies of the West African cultural area, it is thought that some humans are personally linked to an invisible being, a bush-spirit, who has chosen them and comes to live with them. The alliance is sealed by the construction of an altar at the person's home after a long ritual journey. Such a pattern is found in Ghana among the Tallensi [START_REF] Fortes | Religion and morality among the Tallensi[END_REF] and the Dagari (the Bagré initiation, Goody and Gandah 1981: 14), in Burkina Faso among the Mossi (Delebsom 1934[START_REF] Bonnet | Corps biologique, corps social: procréation et maladies de l'enfant en pays mossi, Burkina Faso[END_REF], the Lobi (de Rouville 1984), the Kasena (Liberski-Bagnoud 2012), the Bwaba (Dugast 2015b[START_REF] Dugast | Apparitions et figurations de l'invisible chez les Bwaba du Burkina Faso : 2. Les métamorphoses de l'autel du devin[END_REF], the Toussian1 and the Sèmè, who are the subject of this article. The alliance can lead to the practice of divination for some of these people, with the bush spirit serving as an assistant. In these societies, as well as in others in Africa, when a human thus binds himself personally to an invisible being to access divination, rites generally exhibit the profound transformation he experiences. His appearance or behavior then change significantly. He may even be possessed by the spirit (e. g., the Bassar of Togo [START_REF] Dugast | Stéphan 2010 Figures voltaïques du destin prénatal : du soleil personnel au conjoint de rivière chez les Bassar du Togo[END_REF]; and the Anyi of Côte d'Ivoire -Duchesne 2013). A particular attire and behavior can manifest his transition into a hybrid being where he becomes half-animal or halfbush spirit (the Yaka of the Congo -Devisch 2013; the Bwaba of Burkina Faso -Dugast 2015b[START_REF] Dugast | Apparitions et figurations de l'invisible chez les Bwaba du Burkina Faso : 2. Les métamorphoses de l'autel du devin[END_REF]; and the Kabyè of Togo - [START_REF] Daugey | The Boson' oracle's performance: frame and expressivity in Anyi divination[END_REF]. He may even undergo a more radical transformation, an initial death followed by a rebirth (the Bagré of the Dagari -Goody 1981: introduction; Mwaba-Gurma diviners in Togo -de Surgy 1986: 58-59; the bugo of the Mossi, Bonnet 1988: 64;Kasena diviners -Liberski-Bagnoud 2011). A temporary but recurring transformation may also occur later, when the duly initiated diviner delivers the oracle. He may be in a state of possession, which is then a divination process.

During the rites of induction of a Sèmè diviner, it is the transformation of the bush spirit and not that of the human that is emphasized. When he then practices divination, his appearance and behavior are little changed, and in particular, he never enters into a state of possession. His life certainly is modified by his close proximity to the bush spirit, but to express this important shift in relations, the Sèmè simply resort to the metaphor of marriage. This metaphor is very widespread in West Africa, where male diviners usually see their bush spirit assistant as a spouse, while female diviners see it more as a child [START_REF] Hamberger | Traces des génies[END_REF]. As banal as it may seem, the Sèmè metaphor is quite original. Indeed, Sèmè ethnography enriches the range of relations between the diviner and his bush spirit with a new configuration, that of the diviner who is both the spouse and the child of the bush spirit. The entity that the diviner welcomes to his home and "marries" is indeed not just any spirit from an undefined bush. It actually is the couple of bush spirits, who, in the invisible world, presided over his birth. A matrimonial union with one's parents, even if only symbolically, would lead to incest if the marriage did not include a particular arrangement without sexuality among the Sèmè. In addition, the female bush spirit is supposed to pass the last stage of her own initiation to the dw when settling in the home of the diviner and becoming his spouse. This probably explains why in rituals the transformation of the bush spirit is emphasized rather than that of the human who is already an initiate to the dw .

The dw , the central cult of Sèmè society, is organized around male initiation, which includes many stages, the content of which is a well-kept secret. Initiation takes place in two cycles, one cycle of a few years, which corresponds to the accession of new initiates to the first rank, the other of 40 years, which corresponds to the simultaneous accession of several generations of initiates to the most senior rank. The culmination of this last stage is the d n rite in which they receive their "dw name." Men aged 18 to 35 spend several weeks in a "bush camp." On their release, they dance at large public ceremony held in the village, their faces covered with animal masks that represent bush spirits 2 . Dw is also celebrated every year with ceremonies that set the pace for the farming activities. Other West African societies also practice the cult of dw . The Sèmè listed the Toussian, the Samogho, the Bobo and the Sambla 3 , but not the Bwaba, although their membership in the dw , nevertheless, is well known [START_REF] Capron | Quelques notes sur la société du do chez les populations Bwa du Cercle de San[END_REF][START_REF] Capron | Univers religieux et cohésion interne dans les communautés villageoises "Bwa" traditionnelles[END_REF][START_REF] Coquet | Le soleil mangé : du langage des formes et des matières dans une société sans écriture, les Bwaba du Burkina Faso[END_REF]. The initiation of women to the dw , if there is one, is presented as minor by almost all of these societies, with women ostensibly excluded from the secrets or from some of them. Among the Sèmè, there is a female initiation path, the rites of which are protected by a secrecy even greater than that concerning men. Unlike almost all other societies, which dissociate the initiation path to the dw cult from that of marriage, the Sèmè combine them, as far as women are concerned.

The purpose of this article is to decipher the marital metaphor in the rites of induction for diviners and to show the conclusions which can be drawn concerning their relationship to bush spirits. For the Sèmè, it is perfectly obvious that the path leading to the reception of a bush spirit in a human's house borrows its framework from marriage, whereas the series of allusions that appear in the rites must be shown to outsiders. Indeed, according to the usual process of the ritual, the metaphor is characterized by shortening stages and by implementing shifts and inversions, which makes it difficult for a layman to understand. Diviners and certain specialists particularly connected with the invisible world, such as the blacksmiths and the gravediggers, gave a very coherent explanation of this metaphor. They drew up a list of indices relating to gestures, objects and actions to bring together the two sets of rituals. This deciphering not only brought to light concepts shared by these elders, but also reflected the level of knowledge and the personal views of each of them. The views presented in this article, therefore, are rather those of specialists and knowledgeable elders. Lay people have only a partial or vague idea of the representations which form the basis of the art of the diviners, but the whole of society accords to the implicit system on which it is based (de Surgy 2013). However, the common basis of views relating to divination is not entirely monolithic (Fainzang 1986: 19-20). Both remarks regarding the Mwaba-Gurma and the Bisa also apply to Sèmè society. To reiterate the beautiful expression of a Sèmè diviner, one must 2 They closely resemble those described by [START_REF] Bognolo | L'anima au coeur de 'identit : rencontre avec a cu ture toussian Bur ina Faso Arts and Culture[END_REF] among the Toussian. 3 See also [START_REF] Jean | Organisation de la société en pays Toussian[END_REF] and Dacher (1997: 11-15): "Dogo is the name given to initiation among the Gouin, the Turka and the Karaboro. It is called do (or dwo) among the Toussian, the Bobo, the Bwa and the Dyoro (or Gyoro) throughout the Lobi area". certainly admit that "everyone has his own explanation and there may be some truth in each one."

The welcome ceremonies for a bush spirit are relatively rare events and only men who have received a spirit are allowed to attend all the rites. The data come from the accounts of people reporting their experiences as novices, initiators or mere witnesses of ceremonies, collected in Orodara and nearby Sèmè villages from diviners, healers, household heads and dw cult officials during 16 months of non-continuous field work between 2010 and 2017. The interviews were conducted in s m j n, the language of the Sèmè. Translation into French, the language of administration and education in Burkina Faso, was provided by an assistant who is a native speaker and knowledgeable of their traditions.

A short presentation of Sèmè society is followed by a relatively detailed account of the rites to welcome the bush spirit. Many plants that serve as material support in rites for the establishment of the relationship between the human and his bush spirit are referred to by their names in the language of the Sèmè and their botanical identification is also provided. However, the role of plants and their symbolism are only sketched out as it has been detailed in another article [START_REF] Fournier | Divination with Plants in West Africa[END_REF]. The matrimonial metaphor is not deciphered in the course of the narrative but in the second section. The Sèmè concept of the alliance with the bush spirit is explained in the last section.

THE SÈMÈ, FARMERS OF THE VOLTAIC CULTURAL AREA

The Sèmè make up the majority of the population in six villages of the Orodara Department in Kénédougou Province, Burkina Faso (Figure 1) with a total population of 37,400, including 17,400 in Burkina Faso (Simons and Fennig 2017). Since the 1970s, they have made their living mainly from the fruit crops of mango, cashew and orange trees but still practice subsistence agriculture of cereals and tubers and raise some cattle and small ruminants [START_REF] Fournier | Pratique et perception des feux de végétation dans un paysage de vergers. Le pays sèmè (Kénédougou, Burkina Faso)[END_REF]Bene et Fournier 2014). The Sèmè society was formed in the 17th century from a small group of people from Côted'Ivoire (details in Fournier 2016): their language, the s m j n (ISO 639, Simons and Fennig 2017) is related to the Kru group of languages. Among the Sèmè, there is no centralized power or higher power than that of the village leaders. The village is governed by a dy -r ǃ n, a village chief, a political authority, and by a ɲ ǃ n-t ǃ n, a kind of earth priest, whose role is mostly religious and who is largely subordinate to the village chief. Society is divided into four groups: the farmers who are the nobles and their gravediggers, blacksmiths and griots (placed in this hierarchical order). The family is patrilineal and residence is virilocal. Villages are organized into districts, which roughly correspond to clans identified by food taboos that are mainly related to animals ("totems" in the French translation according to local studies). Families or groups of families are also associated with two kinds of sacred places regarding the foundation of their society, to which their members are individually affiliated. The affiliation to the sacred hills with masculine connotation is transmitted through the paternal line; it marks the alliance with the societies that the Sèmè encountered on their arrival. The affiliation to water with a feminine connotation shows more flexible rules of transmission and is more complex. Their marks refiner social subdivisions in the patrilineal groups [START_REF] Fournier | Setting up the first components of the person and its anchoring to the territory amon the Seme of Bur ina Faso: "services rendered y ecosystems[END_REF].

RITES OF RECEPTION FOR THE BUSH SPIRIT

Recognizing the call of the bush spirit and identifying it From misfortunes to the identification of the bush spirit When a bush spirit wants to force a human to receive it, it resorts to various types of processes. It can bring down misfortunes of all kinds on this human and his entourage. It can make him waste all his wealth. It may seek to ruin relationships with his wife by the fact that disputes break out, the wife leaves for no understandable reason or even dies, the couple remains sterile or the children already born would die.

To determine whether the troubles are indeed caused by a bush spirit who wants to "come to one's home," an initial series of divinations is held. Once this is confirmed, the human should not delay too long to "stake down the bush spirit," in the translation given by the Sèmè of the dedicated expression o4 . Indeed, as long as the person resists, his problems will only get worse. If this person is betrothed, his wedding will be celebrated as soon as possible, because one should be married to receive a bush spirit. In principle, as soon as the bush spirit has been installed and, at the latest, after a ritual stage called "honoring the mother of the bush spirit," the problems cease and the bush spirit provides its protection.

By divination it is specified in which hill (or in which water course associated with a hill) the family of the bush spirit lives. There are about ten of these sacred places, with the generic name "mothers of bush spirits." Each one has its own name borne by all the bush spirits that come from there. People who have received a bush spirit from the same "mother of a bush spirit" are a group of followers who regularly offer sacrifices in this place. Only the members of this group are empowered to install ritually a bush spirit from this place in the home of a new follower.

Personal choices of the bush spirit and the approval of the ancestors Once the "mother of the bush spirit" has been identified, certain requirements for the installation rite -those attached to the place in question -are already known. The bush spirit must also make personal choices, revealed by divinations and led by diviners belonging to the group of followers. The bush spirit indicates, in particular, which plant is suitable for installing its altar and it sets the weekly "rest day" (tārw ) during which the human should neither work ("to go to the field") nor have sexual relations. The bush spirit designates the male follower who is to "hold the wrist" of the bush spirit (kp njá!/wrist catch/), which means leading the ceremonies. It also chooses two women who are to play ritual roles. The bush spirit may also have particular requirements that must be scrupulously respected because it is well known how capricious and fussy bush spirits can be. Thus, it frequently demands that the new follower comply with a particular food prohibition in addition to the "totem" of the "mother of the bush spirit."

The novice and his family then obtain the sacrificial animals required for the ceremonies: goats for a hill, rams for water and a large number of chicken to accompany them. They also prepare an expensive party to welcome the bush spirit. The lapse of time before everything is gathered together is all the longer as the novice finds it difficult to accept to welcome the bush spirit.

At the threshold of the novice's long ritual journey, it must be confirmed that the ancestors have consented to introducing a bush spirit into the family compound. It is for this reason that a sacrifice must be made to their altar, consisting of a pile of stones placed in the courtyard. The answer is given by the position in which a rooster falls when it has had its throat cut, thrown to the ground, and allowed to flap its wings. A negative response is usually only a request for compliance with obligations to invisible entities that have been neglected. The obstacle is then identified by divination and "reparations" are made. Often, it is simply a question of reconciling with a relative after an argument. Sometimes a blood sacrifice is requested at one or more altars, so it may be necessary to postpone the continuation of the rite to another day. This procedure applies for all cases of "repair" that are mentioned below.

Preparation of the house for the bush spirit Once all these precautions have been taken and all the preparations completed, the family can build in their courtyard a round house for the bush spirit, with adobe walls and a straw roof. As a miniature version of the rooms and the traditional kitchens it looks in all respects like the huts for poultry and small ruminants. A small branch of the shrub ty ǃ n-ǃ r (Table I) is stuck into the top of the roof, as well as on that of other constructions that house "fetishes" (tw l) such as protective objects for war and sacred objects of the dw in particular. This branch will fall and disappear with time, but it will be replaced each time the roof is repaired.

Rites for the reception and installation of the bush spirit

Going to find the spirit "in the ush" On the right day -the bush spirit will have indicated it by divination -some volunteer followers accompany the man designated to direct the ceremonies to the site of the "mother of the bush spirit." In this group there is at least one diviner with his materials because it may be necessary to carry out consultations by divination. The novice joins the group. The process of the entire ritual is the same for any "mother of the bush spirit," even if some details may differ from one group to another. Thus, the group of followers may have to fast or remain silent, except for reciting ritual texts. Along the way, quite different plants will be collected, which then will be used to install the bush spirit. The order in which they are collected is not important, but it is imperative to have them on hand on arrival at the "mother of the bush spirit." Most groups of followers do not prohibit collecting the stakes that will be used to make the bush spirit's altars a few days in advance, but they must be left in the bush. When cutting the tree that provides this wood, the followers repeat the name of the bush spirit according to a formula that is particular to each "mother of the bush spirit." Speaking strictly, this is not a secret, but yet it should not be disclosed. Some groups also sacrifice a chicken to the tree; if it does not "respond well," divination and reparations are performed before continuing. A divination kit5 is presented to the "mother of the bush spirit" and is activated for the novice, whereby some groups present only cowries 6 .

Before a quadruped is offered on the altar of the "mother of the bush spirit," it must be ensured -by means of offering chickens-that the bush spirit will accept the sacrifice. A negative answer would lead to a divination and possibly to reparations.

Followers also proceed with the partial charring of certain roots to which sometimes other plant elements are added. Then the only thing remaining to be done is to sacrifice a chicken to the birth water of the novice, which is the place where the female personal bush spirit resides who had helped to bring him into the world. If it is a remote place, only the person in charge of the ceremonies and the novice go there. Finally, the whole group turns back towards the village. As the bush spirit is being transported to the house of the human, everyone wears a crown of the ā r -by l liana that resembles a head pad.

Building the altars

Arriving in front of the entrance of the collective courtyard of the novice's family, the followers place all the stakes on the ground. They first build the altar of the male bush spirit outside the courtyard, usually next to the structure with two entrances that serves as an entrance hall. It is a wooden portico about sixty centimeters high, and consisting of two forked stakes planted in the ground and some smaller branches placed across them. Some groups of followers put three, whereas for others this number is not important, but never should exceed five. Some of the lianas that have been used as crowns are wrapped around the crosspieces, and then a small branch of the shrub ty ǃ n-ǃ r is placed on it. Words that are particular to each group are then recited; they do not seem to have any special power.

In accordance with the protocol in effect for the "mother of the bush spirit" involved, a chicken is sacrificed on the altar that has been built to confirm that the bush spirit really wants to come to this house. If the bush spirit "refused," a divination would be carried out and the necessary reparations would be made before continuing. As in the case of the ancestors mentioned above, a refusal on its part would be a sign that a debt remains to be settled. Some groups first sacrifice the main victim and then check with a chicken that the sacrifice has been approved. The followers then enter the courtyard and confirm that the ancestors accepted the installation of the bush spirit by a chicken sacrifice on the ancestors' altar. If necessary, a divination and reparations are made. Then the stakes and crosspieces left outside can be introduced into the courtyard; they are placed next to the house built for the bush spirit.

Some groups of followers start embedding three small clay pots into the humid soil of the floor of the spirit house and deposit there a bunch of roots called nā n d r (/bush spirit, wood, roots/) 7 . Another small forked root, nā n d rn (/bush spirit, wood, root/), is placed across the pot that occupies the central position. A second portico, identical to the first one, is then built above the pots for the female bush spirit. Some groups of followers place the altar first and use only one or two pots. They then wrap the remaining crowns around the crosspieces and lay a branch of ty ǃ n-ǃ r on it. A chicken is sacrificed on this second altar to confirm that nothing prevents the installation of the female bush spirit in the house. Next, a quadruped of the same species as that offered to the "mother of the bush spirit" is sacrificed. The pots are filled with drinking water for the bush spirit: from this moment on, it is supposed to live in this house. The pots must now be supplied with water regularly. The new diviner, whose activities may keep him away from home for long periods, entrusts this responsibility to one of his wives, but still takes part in the task. The chosen woman now has to remain faithful to him.

One of the women chosen by divination and known as b t r m bré t (/winnowing basket, in, place, the one who/literally: the one who places in the winnowing basket) provides a small winnowing basket made of the Palmyra palm. She is often a sister or sister-in-law of the person who receives the bush spirit. The guests place small gifts (money, cowries) in the winnowing basket to welcome the bush spirit. The woman places them on the altar located in the bush spirit's house. The winnowing basket then will be hung under the altar by the followers responsible for the ceremony where it will remain until it decays into dust; sometimes a ritual wedding broom may be added. Those roots that had been partially charred at the site of the "mother of the bush 7 Examples of these pots are listed in the ethnographic collections of the National Museum of Natural History in Paris where they appear under the numbers MNHN-E-2017.4.14 andMNHN-E-2017.4.15. spirit" are finely crushed by the followers. They then ingest a small amount of the powder obtained and share among them the remainder to take it home.

Serving a festive meal

The ceremony ends with a meal separately served, on the one hand, to the group that proceeded with the installation of the bush spirit and, on the other hand, to the family and the neighbors, and friends who would have been invited for the occasion. The meal of the followers and the novice is prepared by the second woman chosen during the preliminary divinations. The bush spirit may participate in the meal of the initiates, therefore, parcels of food are deposited for it in the little house, either on the ā r -by l lianas of the altar, or in small pieces of broken calabashes arranged on the ground in front of the pottery. However, most groups of followers serve special food to the bush spirit, which consists of a mixture of water and some powdered white seeds or, more rarely red ones (it is a choice of the bush spirit) of the fel plant. This raw dish is like the kind of porridge of Bambara bean commonly eaten by the Sèmè, which of course is cooked. If they have not been able to obtain the fel plant, they ask the bush spirit for forgiveness by presenting it a little plant fetish called ʃ to soothe it.

During the period immediately following its installation, the bush spirit is very vulnerable. As long as certain complements have not been added to the bunch of nā n d r roots (in the pots), no one should enter its little house, which is why it remains ritually closed. During this confinement, traditionally between one and two weeks (5 to 10 days), the novice assisted by his initiators must obtain other things required by the bush spirit. These may include objects to wear, like rings, or roots chosen according to particular criteria (which we cannot detail here) and which will be added to the nā n d r.

During this period the bush spirit indicates to the novice in a dream whether or not he may immediately begin to practice as a diviner. Often those who are in full activity will begin to practice divination only later, when the bush spirit asks them to do so. A bush spirit who chooses not to be involved in divination is called a o (/deaf-mute bush spirit/). In all cases the novice receives a protective object against witches called s -dǃ ǃ r (divination tail), made of a secret mixture of ingredients, including plants. In principle, he must carry this object as soon as he leaves home, while the rest of the divination equipment remains stored there (usually in the bush spirit's little house).

Rite of confirmation of the alliance

Three years after the installation of the bush spirit, the group of followers returns to the "mother of the bush spirit" to perform the rite of ty ǃ n n ǃ (/bush spirit, mother, to rise/literally: to honor the mother of the bush spirit). This rite is identical to the rite performed to seek the bush spirit, except that no more plants are collected or processed, and no crowns are worn. The same sacrifices are offered and the meal again served to the bush spirit must include exactly the same dishes as for its reception.

Reaching the stage of the ty ǃ n n ǃ means that the bush spirit has validated the alliance. Before welcoming his bush spirit, the novice had been asked to get rid of the "bad things" he may have, that is, fetishes that could perpetrate witch attacks. If he had not obeyed or if in the meantime he had procured such things again, the bush spirit would have killed him before the expiry of the three or four probationary years.

Once the ty ǃ n n ǃ ceremony has been performed, the novice is entitled to make himself blood sacrifices for the "mother of the bush spirit" without entrusting them to the older followers. Future diviners benefit from the period prior to the ty ǃ n n ǃ ceremony to acquire the knowledge needed in order to perform divinations. They do this under the direction of a master who is one of the diviners of their group of followers, but the bush spirit also gives them his instructions in dreams. If the novice is quick-witted and his bush spirit helps him, this apprenticeship would not take more than three weeks.

DECRYPTING THE MARITAL METAPHOR

The Sèmè betrothal According to the Sèmè, the preliminary steps that the future diviner makes before the installation of his bush spirit are comparable to those which would be carried out for a betrothal.

In the Voltaic societies, marriage is generally seen as a long and gradual process of transferring the wife from her parents' house to that of her husband, into which she will gradually integrate, step-by-step, and more or less completely, depending on the society. Among the Sèmè, the wife must ideally devote herself entirely to the well-being of her home, be submissive to her husband and absolutely faithful to him. When she dies at an old age, having had children and passed through all the initiation stages, she is totally integrated into her husband's family and she is incorporated into the altar of the ancestors of the extended family. She then becomes a guardian for whom her children can perform sacrifices.

Today, there is freedom of marriage, but traditionally, a girl was betrothed by her parents at the age of about 8 to a boy of about 17. The fianc e's parents received from the parents of the fiancé a ritual gift of dolo 8 , followed by assistance in their fields for several years. The girl then went back and forth between the two houses. As soon as she was old enough, she had sexual relations with her fiancé, but she was not yet considered married. The girl's marriage would not be effective until after the ty l, the first step of her initiation in the dw .

Although the male and female processes are separate, the Sèmè establish a very precise correspondence between initiatory grades (Table II). The boys go through the first stage of their initiation to dw at the same age as the girls (around 15 years old), during a ceremony also called ty l. Formerly, they were circumcised in a peer group, but today the operation is done at the clinic when they are babies. For them, the ty l stage is independent of marriage, but the latter is not accessible until after the d tyǃ ǃe, a stage that confers a sort of social majority. During this rite, they touch sacred objects that were shown to them during the stage of ɲ -fǃ ǃ . Only the seven oldest initiates in each district gain access to the ultimate initiation stage, that of the "elders of the dw ", where they hold all the secrets and direct all the rites. Table II. Correspondence between male and female initiation grades in the dw Female initiation path Male initiation path ty l ty l ɲ -fǃ ǃ (/eye to sprout or to split/literally: to pierce the eyes, to open the eyes) fy (/fy , to place/literally, to place the fy ) d tyǃ ǃe (/dw , dolo, pour-put/ literally: to pour the dolo of the dw ) d n (an initiate) 8 In French-speaking West Africa, the term dolo refers to locally made fermented beverages. The Sèmè use this term to translate a generic term that refers to both red millet beer and palm wine. ty -d (/marriage, to enter/ literally: to enter a marriage Elder of the dw

The ty l marriage and the transfer of the bride and allusions to it in the rite Even today, the ty l ceremony still marks the moment when the fiancée goes to live with the man who is now officially her husband, even if they no longer practice the excision that was once associated with it. The operation was formerly followed by a period of confinement, which corresponded to the time necessary for the wounds to heal. This period of confinement is still observed, but today it is shorter. A great celebration, the ty w w ŋ (/ty l, entertainment or party/) is then held. The young bride holds in her hand a ritual broom made of the plant j n r. The griots sing her praises while she receives cowries, cash and small objects in a small winnowing basket identical to the one used by boys during their own ty l. She places these gifts in a larger basket ( w n 9 , see Table I) where they keep the larger gifts (cloths, etc.) that have been placed there directly. A woman chosen by divination, as a kind of marriage witness, would have been commissioned to make or buy this basket that she has to carry during the whole celebration. To honor the bride, the men and women of the husband's family carry her alternately on their shoulders and dance. The young woman will now live with her husband where she has her own house and kitchen. The expenses of a girl's ty l are borne by her fiancé's family, which is why it is said that the husband ensures his wife's initiation.

The ritual moving of the bush spirit from the "mother of the bush spirit" to the house of the human being is interpreted as reflecting the bride moving from the home of her parents when she comes to live with her husband. The celebration held on the arrival of the bush spirit is equivalent to that held for a ty l. The confinement of the bush spirit, the presence of the b t r m bré t woman, and the little winnowing basket that she has to take care of are a transposition of the elements of a ty l ceremony as well as the broom. The day reserved for a "break from sexual relations" imposed on the novice in the name of the bush spirit suggests that the husband, if he already has one or more wife, must reserve the nights for his new wife. It is the future diviner and his family who provide for all the expenses related to the reception of a bush spirit just as in the case of the reception of a wife.

The confirmation of marriage fy gbe

The second stage of the Sèmè marriage is called fy . It expresses the harmonious relationship of the couple. Fy is carried out individually for each wife at the discretion of the husband but with the agreement of the wife's family. This rite is usually performed several years after the ty l. During the sequences that alternate between the two households, the family of the husband offers food items to the family of the wife and the fy , i. e. a small quantity of uncooked food items, is ritually placed on the bride's ersona fetish of the "luc ". Everyone has personal "luck," represented by a small pot that is honored individually with sacrifices [START_REF] Fournier | Setting up the first components of the person and its anchoring to the territory amon the Seme of Bur ina Faso: "services rendered y ecosystems[END_REF]; that of the wife is placed at the home of her husband. When cooked and prepared, the fy is served to the initiates with a rank of at least fy . A ceremonial meal, to which everyone has access, is 9 Examples of these baskets have been donated to the ethnographic collections of the National Museum of Natural History in Paris where they appear under the numbers MNHN-E-2017.4.7 andMNHN-E-2017.4.7. cooked with the remaining food and served. Once the fy has been performed, the wife has the right to perform certain marriage rites for other women.

The marriage of complete integration ty -d

The ast sta e of a woman's initiation is ca ed ty l-d (/marriage, enter/ literally: enter the marriage). It is also performed at the discretion of the husband and with the agreement of the wife's family. She may then be 40 or even 50 years old. The ty -d is a ceremony that is always held for several wives in the same household, all those of the husband and often other women of the compound. It represents a perfect union between the spouses, without any possibility of separation and enables to perform all the marriage rites. The husband now has the right to "claim her body" wherever the wife may be when she dies10 and to perform for her the rites of transmutation into an ancestor.

Certain sequences of the ty -d are held at the husband's home, others at the homes of the family of each wife. In each of the family homes from which the wives originate, women who have already been initiated lock themselves into a room reserved for this purpose to perform a secret ceremony. During a sequence of the ty -d , the men of the family of the husband come to seek the wife who awaits in her parents' home; they call out to her "here is the price of your sex", throwing cowries on her, which she will keep to herself. A ritual object made up of a stack of small baskets bordered with leather and bearing at the top strips of leather decorated with cowries11 is then given to her. She can use these recipients for her work (in particular at the market). The rites of the ty -d are long and they involve several walks, where all the households concerned by the event are visited, including at night. During these trips, the way is lit with a traditional lamp, the flame of which has undergone a special process to provide it with power against witches. This lamp then is given to the wife. A visit and the sacrifice of a chicken are also due to the birth water of each ty -d wife. The ty -d is an expensive celebration, usually paid for by the husband.

What makes the ty -d wedding special is that a man other than the husband can pay for it as a mark of friendship or consideration for the couple. It is thus a great honor for him and for them. However, one can pay for the ty -d only for someone from his or her own social status group or a lower-level group. In particular, the ty -d is performed for relatives or for the wives of sons. When a man other than the husband "performs a ty -d for a woman," he becomes a sort of a father-in-law, thus excluding him from sexual relations and marriage with her, even after the death of her husband. The woman, who refers to the husband with whom she has sexual relations by the term d e (husband) uses terms of respect for the man who pays for her ty -d , such as ky l (maternal uncle) or t (father). The couple then should show consideration for this "uncle" and perform small services for him. In particular, the "uncle" is entitled to expect a punctual participation in field work as well as the ritual sweeping of his courtyard at the annual dw ceremonies: the husband takes care of the courtyard outside, while the wife takes care of the inside. Lastly, when the "uncle" dies, the woman must mourn like his own wives. After the ty -d ceremonies the "uncle" is given the traditional protective lamp and not the wife. He may keep it, but he usually gives it to her.

Ty ǃ n n ǃ , a combination of fy and ty -d marriages

The list of indices that non-specialists can provide for the reading of the rite as a marriage is limited and not devoid of blur or contradictions. In the ty l and fy stages specialists recognize a marriage between the bush spirits without hesitation; they are sure that there is a sexual union between them. However, they need time before declaring that the human who welcomes the bush spirits performs their ty -d and that he has no sexual relationship with them. Indeed, the rite ty ǃ n n ǃ appears to be a kind of condensed fy and ty -d , including a festive meal, a visit and a sacrifice to the "mother of the bush spirit." It shows that the union between the human and his bush spirit has become closer. More precise indices, interspersed throughout the rite, suggest these two marital stages.

Thus, the special meal served raw to the bush spirit recalls the ritual deposit of a portion of raw food (fy ) on the personal fetish of the wife during fy . The ritual closure of the bush spirit's house fully integrates the bush spirit into the family, as does the fy stage of the female marital path12 . It is also reminiscent of secret rites performed inside a house by women during ty -d . In addition, during this stage sacrifices to the birth water of the follower are performed, in the same way as they are performed to that of a wife for whom the ty -d is celebrated.

The "divination tail" against witches given to any diviner in some respects may be seen as an equivalent for the traditional lamp given to the benefactor who supports the ty -d of a couple. The anti-witch power of its flame is echoed by that of the mixture contained in the fetish.

We can also consider that the spatial positioning of the two bush spirits (or rather their altars) alludes to that of the couple during the ritual sweeping in front of the door and in the courtyard of the man who celebrated their ty -d . Lastly, the divinatory work of the bush spirit as an auxiliary to the diviner can be understood as one of the wife's services she has to provide to the man who performed her ty -d .

With regard to those bush spirits who played for him a parental role in his conception, his birth and throughout his life, the diviner behaves like a respectful and loving son. An adult son who wants to perform the ty -d for his wives first has to undertake the same for his parents, in case this not had been done yet.

THE SEME VIEW OF THE ALLIANCE WITH THE BUSH SPIRIT

Ty ǃ n, a concept of the relationship between humans and bush spirits

The "domestication" of the bush spirit, elements of language As has been pointed out several times, the rites highlight the transformation of the bush spirit and not that of the diviner. In fact, language elements confirm this. There are indeed two terms that can be translated as "bush spirit." 13is a very general word that applies to all bush spirits, the good or bad ones, and whatever their relationship with humans is. Thus, it may refer to a bush spirit living in the bush with no particular link to humans, as happened in "root(s) of the bush spirit" ( nā n d r and nā n d rn) and "calabash of the bush spirit" ( ā ). It also describes a bush spirit installed in the home of a human as in "thing to seat the bush spirit" ( ɲ n -m n 14 ) and "deaf-mute bush spirit" ( o 15 ). The other term, ty ǃ n, is only used for bush spirits that have a close relationship with humans. It is found especially in "honoring the mother of the bush spirit" (ty ǃ n n ǃ 16 , in the name of several species of the Gardenia shrub (ty ǃ n-ǃ r) used during the installation of altars for bush spirits, and in the term designating these altars. Although the full name of this wooden construction planted in the ground is ty ǃ n a n (literally: the bush spirit's legs), it is usually called just ty ǃ n, as if it were the bush spirit itself.

Moreover, regarding the human who sets up the altar or his bush spirit, it is said that he "stakes down the bush spirit."

Such ambiguity in the use of a term designating bush spirits fits perfectly with their essentially unknowable nature and their transformative powers. In the hands of the followers it is also an educational tool when they want to explain the union of a bush spirit with a human. Thus, one of them successively declared that the altar "was" the bush spirit, then that it was more correct to say that it "made" the bush spirit, and, finally, that primarily the bush spirit is referred to as ty ǃ n, which is completely distinct from the altar. Another diviner made an additional step by explaining that it is not really the bush spirit that is in the house, but rather its promise (ɲ nt ǃ -kw ǃ n/mouth, coming from, word/). When asked about the meaning of ty ǃ n, several elders, who were among the most knowledgeable on the world of the invisible, firmly stated that ty ǃ n is a bush spirit that has formed an alliance with a human. By indulging in such a play of metonymy in the vocabulary associated with the bush spirit installed at home, the Sèmè indirectly indicate that although ty ǃ n designates a bush spirit related to a human, as the elders said, the corresponding altar above all is witness of the transformation of the relationship between these two partners 17 . The process of progressive penetration of the bush spirit into human space seems to be part of the semantic field of ty ǃ n as much as the achieved result (installation of the bush spirit). This allows for a certain distancing from a too literal interpretation of the two bush spirits who come to the house.

Attempt to define the concept of ty ǃ n

The division of the bush spirit into male and female during the construction of two altars can be interpreted as indicating a transition from the status of to that of a domestic or domesticated ty ǃ n. During this transition, the bush spirit seems to assume the gender connoted by the spaces it moves into at each stage: first, it is male when it is installed outside the courtyard (a masculine space), then it is female once installed in a room (a female space). From this perspective, the male form of bush spirit primarily can be seen as the path taken by the being from the bush during the transformation that allows it to live near people. Indeed, even if the Sèmè specify that the female is dedicated to divination work and that the male exercises its authority over her from the door, in other sequences of the same discussion they can refer to the couple of bush spirits as one single individual. It should be noted that in a society where the allocation of names (at birth and during initiation, when even bush spirits receive a dw name) is so 14 Name of the repository for the divination stone. 15 This bush spirit does not want to perform divination. 16 The last ritual stage of the welcome. 17 Regarding the nanwamu altar set up among the Bwaba when a bush spirit decides to have a special relationship with a human, Dugast (2015b) wrote "It is this re ationshi that the object shows, not the entity that is at its ori in". important, male and female bush spirits only bear one single name, which is that of the site from which they come, wherever the compound wherever they are installed may be located.

The transformation of the bush spirit in Sèmè oral texts During the divination, the diviner always relates the story of the arrival of its bush spirit. A version of this sequence includes a dialogue between the diviner and his bush spirit. The latter is presented as a unique individual who, once installed at the door, demands to penetrate right into the compound:

The bush spirit told me to take it home and I said I could not afford it.

-Then you will not live long! [This is the bush spirit speaking] -It's fear that made me go and see the elders and bring you home. You've been told to sit at the door and we can see each other during the day.

-No, I live in houses! -That's why you're inside. If a word comes into the house, it is yours. 18Once the bush spirit has been ritually transformed into ty ǃ n, the human being and the bush spirit are in a new relationship that initiates the possibility of communication between their two usually separate worlds, the visible and the invisible. This possibility will only be fully activated, however, if the human becomes a diviner.

The idea of a transformation of the bush spirit that comes to the homes of humans is also contained in an account of the Sèmè on the beginnings of the matrimonial exchange. There it is said that the first human family sent by J s (the Creator) to the earth lived in isolation while bush spirits were already settling the land. They had never met, until a family of bush spirits who lived nearby decided to visit the humans. The bush spirits presented themselves in human form. The son of the bush spirits immediately fell in love with the human girl and asked to become a human to be able to marry her. The conclusion of the story is that the family founded by this young couple was the first with whom matrimonial exchanges began. When one has received a woman from another human group, one has to give in return one from the own group. Therefore, this story justifies the installation of female bush spirits into human families.

Historical and mythical resonances of the welcome of bush spirits

The Sèmè people were a small population group when they arrived. According to their memories, their society has grown up around a small group of newcomers through alliances (including marriages) with other people. The alliance of the Sèmè with the communities already present there had been by sharing the sacred hills. This sharing established a link of agnatic nature between them and integrated the Sèmè into the local communities. Symmetrically, some neighbors have been incorporated into Sèmè society. Indeed, several villages were founded by a Tussian who became Sèmè after marrying a Sèmè woman. Viewed from this angle, the story of the bush spirit who changes into a human to marry the daughter of men can be interpreted as a metaphor for the assimilation of foreigners by the Sèmè. The couples of bush spirit-spouses received by the diviners are indeed radical foreigners. The "mothers of the bush spirit" from which these bush spirits come are at the same time the places where an alliance with the neighbors was concluded and those who provide children to the Sèmè.

The spouse-parent bush spirits and the conception of the person People who have received a bush spirit at home emphasize the trauma they have suffered and speak of it as a capricious intruder they had to live with. Its installation produced a break in their lives and a sort of reorganization accompanied by relief.

At another level (that of the learned commentary of the diviners), the arrival of the bush spirit is understood as an element of the personal destiny of the human and owes nothing to any whim on its part. A previous work [START_REF] Fournier | Setting up the first components of the person and its anchoring to the territory amon the Seme of Bur ina Faso: "services rendered y ecosystems[END_REF] showed how, among the Sèmè, the arrival of a new individual in the world results from the reincarnation 19 of a permanent principle called nw coming from generation to generation to lodge in a new body. During the journey that the nw makes into the invisible, it establishes a program called by -myā (/arrival/voice) before God 20 and the ancestors and freely takes on commitments. This journey is made under the tutelage of a couple of personal bush spirits (male and female) who will look after the individual throughout his life. One of the promises then made by the nw may be to install his personal bush spirit at home. This pair of bush spirits, that plays a role of supervision and protection, ensures that the debt that their protégé has completely forgotten, of course, is repaid. They send various warning signs to trigger their reception process, because a forgetful human regarding his prenatal promises is in danger. The support for their ty -d marriage, provided by humans, is explained by the diviners as a testimony of friendship and recognition for the "work" they have done, as might occur between humans, especially between parents and children.

Divination and personal destiny: a Voltaic representation

There is evidence in the rites with respect to the idea of destiny. The collective name of the Sèmè personal bush spirits, ŋm tā (/head on bush spirit /literally: bush spirit on the head), should be compared with the use of the ā r -by l liana to suggest a head pad placed between the head and the bush spirit that is carried towards the house of the human. This porterage suggests, of course, carrying the bride on the shoulders during ty l. However, this detail takes on a deeper meaning in light of the ideas encountered in two other societies of the Voltaic cultural area. Among the Bassar of Togo, where divination is also an element of personal destiny, they speak of a cushion on the head to evoke the prenatal debt that one has to repay by becoming diviner (Dugast 2010). Among the Batammariba of Togo, the divination entity is also associated with human heads: the future diviners who are still children must wear a special hairstyle to provide temporary shelter for (and neutralize) the divinity of divination that enters into their bodies by the fontanel and disturbs them [START_REF] Blier | Diviners as alienists and annunciators among the Batammaliba of Togo[END_REF].

Other elements of the Sèmè representations echo concepts of divination widely used in the Voltaic cultural area. As we have seen, the personal bush spirits, welcomed by the follower come from "mothers of bush spirits," i. e., sacred hills, which seem to mediate access to divination. These hills, in principle located outside the village but near to it, are places of the foundation and origin of agnatic groups that form the Sèmè society. Each individual also depends on a "birth water" located in the community or its immediate surroundings. Although the affiliation to the hills and waters is presented as individual and there is a certain degree of freedom in this regard, members of the same 19 It seems to be a real reincarnation as in the case of the Toussian [START_REF] Jean | Re r sentations de 'âme et de 'au-delà chez les Toussian (Burkina Faso)[END_REF][START_REF] Bognolo | L'anima au coeur de 'identit : rencontre avec a cu ture toussian Bur ina Faso Arts and Culture[END_REF], whereas societies in these regions are usually vaguer on the subject or present things differently (Bonnet, 1988: 92;de Surgy 1983: 71;Cartry, 2010: 65; our own unpublished surveys among the Bwaba). 20 Unlike other Voltaic societies (Liberski-Bagnoud 2010b; Dugast 2010), the Sèmè do not seem to associate the figure of the sun with that of the creator god [START_REF] Jean | Notion et culte de Dieu chez les Toussian[END_REF]. lineage are generally affiliated with the same sites (see [START_REF] Fournier | Setting up the first components of the person and its anchoring to the territory amon the Seme of Bur ina Faso: "services rendered y ecosystems[END_REF]. In various Voltaic societies (Tallensi, Nankana, Sisala, Bissa, Kassena), the oracular power (the "place from which the oracle flows") is likewise closely attached to the lineage of the diviner (Liberski-Bagnoud, 2012) and often associated with "topical deities" (Liberski-Bagnoud, 2010b: 126). Thus, among the Kasena, the oracular instance vʊgʊ (which is not a bush spirit) is associated with one of the sacred groves that ensure the "ritual construction of the origin of each lineage of the village community." These groves are the places where the "lives" of lineage members are deposited. In association with another power called dʊna, that is the exclusive property of the lineage, they make births occur in this lineage. It is through dʊna, a kind of "ritual mother" described as an "old backwater whose water never runs out," that newborns are integrated into their lineages. A replica of the dʊna, represented by a clay pot filled with liquid, is present in each house (Liberski-Bagnoud, 2002: 83-84, 92).

CONCLUSION: A DULY PROGRAMMED RECEPTION

The Sèmè concept of the reception of a bush spirit which provides a human with access to divination undoubtedly belongs to the representations of the Voltaic cultural area, although it has certain original features.

In order to facilitate the communication between the worlds of the visible and the invisible, a human and a bush spirit must be brought together. As in other societies, it is by the insertion of a bush spirit into a human family that this essential proximity is established among the Sèmè. The main aspect of this bush spirit is its double status: at the same time it is a parental couple and a special kind of spouse. Attributing such a marital status to the bush spirit is conceivable only because there exists in the Sèmè institution of marriage an arrangement by which a man can "marry" another couple who already have passed the first stages of marriage. By interpreting the reception of a bush spirit through the matrimonial metaphor, this special feature makes it possible to associate in the same institutional block various ideas relating to the creation of the person in general and of the person who is a diviner in particular.

The duration of the Sèmè marital journey and the spatial displacement it entails give an image of the effort required to integrate into the human world a being as radically alien as a bush spirit. The young wife who leaves her parents' home to come and live with a new family very gradually becomes a full member of the family who welcomes her. But to become one, she has to go through various ritual stages that are under her hus and's contro and which could be seen as a sort of a test: integration is the reward for good conduct. Like the wife, the bush spirit moves from its native environment of the bush to integrate into a foreign family (here human) in several stages, however, in a reverse situation, it is the bush spirit who tests the purity of heart of the human who welcomes it.

The assistance of the Sèmè specialists is invaluable in unraveling the relationships within the astonishing trio formed by the follower and his pair of bush spirits. The first two marital stages mentioned in the rite of welcome (ty l and fy ) refer to the union of the bush spirits between them. Thus, it should be remembered that every human being is symbolically engendered in the invisible by a male principle and a female principle, which then watch over him during his entire existence. The third and final marital stage (ty -d ) introduces the idea of a union of a completely different nature, that of the couple with a third party. It corresponds to the human's fulfillment of a filial duty towards the pair of bush spirit-parents, which conducted his soul and assembled the components of his person. This special marriage, which bush spirits come to demand, allows linking divination, the prenatal alliance inherent in the person, with the question of personal destiny and that of initiation.

Figure 1 .

 1 Figure 1. Maps of the study area (by Douanio Manaka on a map background of 1:50,000 of the Institut Géographique du Burkina)

Table I .

 I Botanical and vernacular names of the plants cited in the text

	Construction materials for the altar
	Afzelia africana Sm. ex Pers.	FABACEAE	ǃ
	Diospyros mespiliformis Hochst. ex A.DC.	EBENACEAE	k m
	Pericopsis laxiflora (Benth.) Meeuwen	FABACEAE	w
	Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler	RUTACEAE	w
	Little branch placed on the roof and the altars
	Gardenia erubescens Stapf & Hutch.	RUBIACEAE	ty ǃ n-ǃ r
	Gardenia ternifolia Schumach. & Thonn.	RUBIACEAE	ty ǃ n-ǃ r
	Meal for the bush spirit
	Phaseolus lunatus var utilis L.	FABACEAE	fel
	Little winnowing basket and larger basket
	Borassus aethiopum Mart.	ARECACEAE	n
	Ritual marriage broom
	Eragrostis tremula (Lam.) Hochst. ex Steud	POACEAE	n r
	Latin binomial	Family	Name in s m j n
	Crowns and transportation of the pickets
	Cassytha filiformis L.	LAURACEAE	ā r -by l

Legend

Latin binomials according to the Conservatoire et Jardin Botaniques de la ville de Genève (2012) ; vernacular names according to

[START_REF] Boyd | Nignan 2014 Une base de données informatisée transdisciplinaire de la flore : un outil pour l'étude du lien nature-société[END_REF]

with additions.

Guilhem and Hébert (1964), 1965;[START_REF] Cooksey | Iron Staffs in the Crossroads: Art and Divination in Toussiana. A Southwest Burkina Faso Community[END_REF];[START_REF] Bognolo | L'anima au coeur de 'identit : rencontre avec a cu ture toussian Bur ina Faso Arts and Culture[END_REF].

The verb kpé is used to refer to a stake driven into the ground -an operation that is actually part of the installation rite -but also to describe a person or a tree that stands upright and motionless. The expression refers to ritual gestures that will be described later.

This material includes a flat black stone, six cowries, and the horn that contains them, a forked stick, two metal bells, and several small plant fetishes.

The details of these rites have not been described to us.

In practice, the corpse is symbolically "brought back" while the remains are buried at the place of death.

Such an assembly appears in the ethnographic collections of the National Museum of Natural History of Paris under the numberMNHN-E-2014.1.11.

The d tyǃ ǃe initiation grade of a young man, which consecrates him as a responsible adult, is of the same rank.

We did not considered a third term, w kl n n, reserved for evil bush spirits. The word seems to have been borrowed from the Dyula language and it does not match necessarily the Sèmè representations who also differ very much in defining precisely the meaning.

Divination by Mr. Gwene Traoré (September 25, 2013).

Acknowledgements: As a representation of the Sèmè who generously shared their knowledge on the bush spirits and the invisible we want to thank Mr. Gwene Traoré, Village Chief of Orodara and a diviner. We thank Saïbou Nignan for the help in the identification of plant species, G. Fabre and R. Boyd for access to the linguistic database, Hamadou Coulibaly for the translation from s m j n, Douanio Manaka and Laurence Billault for creating the village map. We thank Jean-Pierre Jacob, Klaus Hamberger and Jean Boutrais for their re-readings of preliminary drafts. This text also owes much to the reflections in the research seminar "Sexual spaces: mask and possession" by Klaus Hamberger. The research was funded by IRD UMR 208 Paloc and the interdisciplinary program RADICEL-K (http://radicel-k.huma-num.fr/).

Surgy (de), Albert. 1986. La divination par les huit cordelettes chez les Mwaba-Gurma (Nord-Togo). 2 L'initiation du devin et la pratique divinatoire. Paris: L'Harmattan. Surgy (de), Albert 2013 Why divination is an important topic. In van Beek, E.A. and Peek, P. M. (eds), Reviewing reality. Dynamics of African divination ; pp. 141-158. Berlin Zürich : LIT Verlag. Van Beek, Walter E. A., and Philip M. Peek (eds.) Reviewing Reality. Dynamics of African Divination. Wien: LIT Verlag. (Afrikanische Studien, 50) ABSTRACT Among the Sèmè, a little-known society in the Voltaic area, some men receive at home a couple of bush spirits through which they get access to divination. They form groups of followers of the spirits. The rite implemented borrows its fabric from marriage, a long process that extends over a woman's entire life. The follower "marries" the bush spirits according to an original marriage arrangement without sexuality. He is bound to these bush spirits by a prenatal promise, his symbolic parents, who were assemblers of his person. [Burkina Faso, Voltaic cultural area, personal bush spirit, personal destiny, prenatal alliance, transformation, displacement] BIOGRAPHY Anne Fournier has been a researcher at the Research Institute for Development (IRD) since 1983 and has lived in Côte d'Ivoire and Burkina Faso for several years. She first became interested in the ecology of the Sudanian savannahs (ecosystem energy flows, structure and dynamics of vegetation). From 2002 to 2006, she led a multidisciplinary IRD Research Unit dedicated to protected areas. She participated in studies on fallow land, bush fires and the pastoral use of savannahs. For the past ten years she has been conducting ethnobotanical and ethnological studies on the ritual uses of plants among the Bwa (in Bondoukuy) and Sèmè (in Orodara) societies in Burkina Faso, particularly in divination.

Main publications in


Raphaëlle Bats
email: raphaelle.bats@enssib.fr

Keywords: freedom of expression, censorship, librarianship, public service, neutrality, engagement

Introduction:

In the beginning of January 2015, attacks on Charlie Hebdo and the HyperCacher kosher supermarket in France rocked the nation, and the French people suddenly found themselves confronted with the violent reality of what it means to be denied freedom of expression, freedom of the media and the freedom to believe. In a country where some of the Charlie Hebdo draftsmen, such as Cabu and Wolinski, were known by several generations (whether through their drawings in other newspapers or on television), this event had a great emotional impact on the French people, and was followed by a large mobilization of citizens in a march on January 11 th .

As information professionals, France's librarians reacted immediately, posting messages of support for Charlie Hebdo and/or messages against censorship, and displaying the Je suis Charlie ("I am Charlie") sign inside and outside of their libraries, in exhibitions of journalistic art, and in selections of resources and conferences on laïcité1 , freedom of expression, and so on. In a spectacular gesture, the library of Pierres-Vives in Montpellier nearly emptied its bookshelves in order to symbolize censorship. Though all these actions and mobilizations are praiseworthy, it remains unclear how exactly these actions can be linked to the duty of French librarians to uphold neutrality and confidentiality [START_REF] Hubert | Bibliothécaires et militantisme: neutralité et pratiques professionnelles[END_REF]. Were these the actions of civil servants working in cultural institutions to uphold the pillar of democracy, or the emotionally driven actions of French citizens, carrying a certain vision of freedom and community, but centered above all on the event itself? In other words, how have these political acts confronted the librarian's role as a citizen on one hand, and on the other, a civil servant working in perhaps the only public arena for the application of democracy?

In order to better understand the role of French libraries during times of crisis, and their relation to neutrality, a detailed study on the kinds of actions that were carried out after the attacks was necessary. The following article is based on a survey of around 200 actions that were carried out between January 7 th and late December 2015, and will be presented in three parts: first, a presentation of the methodology implemented in the collection and analysis of the data, second: an analysis of the results, and finally, a discussion concerning neutrality, political engagement and debate.

1: Methodology

1A: Theoretical Framework

The question of neutrality in French libraries has been examined in library charters, laws, codes of ethics, and so on, both at the national and international level. In times of crisis, however, this duty to uphold neutrality, and the ways in which it is performed, is often reevaluated.

In 1999, Jean-Luc Gautier-Gentès responded to certain acts of censorship carried out by far-right local governments on their libraries, and pressed the duty of the librarian, both a potential (and even probable) censor and defender of free speech, to take a political stance: "This is the case with librarians. Also, as we've searched for ways to help librarians avoid arbitrary decisions, should we not now be searching for ways to protect citizens from arbitrary decisions, to which librarians themselves can contribute?" [START_REF] Gautier-Gentès | Réflexions exploratoires sur le métier de directeur de bibliothèque[END_REF]. He also examines the paradoxical position of the librarian, a civil servant and citizen, a political actor subject to both neutrality injunctions and the duty to exercise discretion: "…the library thus presents a sort of double-aspect. On one hand, notably, it contributes to the molding of minds (including the particularly vulnerable minds of children), in which case it seems that neutrality is understood to be of the utmost importance, and held to a more scrupulous standard than in other public services (excepting schools). On the other hand, the fact that libraries find themselves in the position of having to manipulate pure politics, politics that are shown more or less as they are, notably the in news, means that neutrality appears to be markedly more fragile and threatened than in other public services." [START_REF] Gautier-Gentès | Réflexions exploratoires sur le métier de directeur de bibliothèque[END_REF] In a 1999 text written in the same political context, Anne Kupiec pressed the eminently political and critical role of the public cultural institution: "As a public service, the library is committed to four well-known principles: continuity, adaptability, equality and neutrality. In the case of neutrality, it means that libraries must not promote any personal opinions (especially political or religious opinions, or racial biases) when carrying out their services, and in doing so avoid a critical conception of the constitution of the collections". She recalls the contours of emancipation, a democratic opportunity in which libraries play a key role. Her texts question libraries' actual capacity to emancipate citizens. "From a historical perspective, it is obviously in libraries' interests to remember the use of critique in the fight against ignorance and belief, as well as the fight for the advent of Enlightenment for all, and consequently, to show the soil in which the development of the library slowly and sinuously took root." [START_REF] Kupiec | Éléments de réflexion pour une déontologie professionnelle[END_REF].

Finally, in 2015, three months after the attacks of January 2015, Anne-Marie Bertrand examined the role of the public institution in the debate and conflict, recalling the state sources of the role of libraries as places of education and emancipation. "The analyst observes an avoidance of politics rather than a strong articulation, because the library is in an ambivalent position: on one hand, assuming its civil role, and on the other, assuming the role of an institution devoted to maintaining social links. Firstly, the library represents political conflict via pluralism. Secondly, it cultivates a "vivre-ensemble"2 , elevating that which unites over that which divides." (Bertrand, 2005).

In this article, we aim to examine the actions carried out in the wake of the attacks through the lens of the three following approaches to neutrality: the possibility of discussion and political action on the part of libraries, their willingness to enter into debate and process conflict, and the paradoxical position of the French librarian.

1B: Statistics

On January 11, 2015, we3 launched the "#Bibenaction" campaign on Twitter, which called upon French librarians to share the actions carried out by their libraries in the wake of the attacks. This first step in the survey was conducted using Internet searches as well as first-hand accounts4 . These actions were collected and listed on Twitter in an improved 5 Excel spreadsheet, which allowed us to organize the collected actions by the following criteria:  Type of action: message, exposition, selection, acquisition, debate, meeting, free speech, or professional action. This was to see what kinds of actions were carried out in a time of political crisis.

 The presence or absence of Je suis Charlie ("I am Charlie"), whether in the form of a photo, a message, a news headline, a blog post title, a hashtag (#jesuischarlie), or otherwise. This was meant to gauge the presence of this message in cultural institutions that used the image or slogan as a means of mobilization, or even counter-mobilization (for example, using the message Je ne suis pas Charlie, or "I am not Charlie").

 Type of library: public libraries, territorial libraries, academic libraries, national libraries, and professional organizations. This was to see in which kinds of libraries the attacks reverberated the most.

 City: this was to measure the distribution of the actions throughout the French territories.  Date: this was to delineate the different phases of political action in 2015.  Means of communication: websites, social media, email, the press, and so on. This was to see how libraries and librarians gave visibility to these actions.

 Theme of the action: freedom, solidarity, cohabitation, and so on. This was to see what motivated and triggered the action.

The actions thus identified with this table were then passed through the filter of our theoretical framework in order to find some answers answers to our question regarding neutrality.

2: General Results

2A: General Results

The survey allowed us to identify 187 different actions 6 .

These actions were carried out by all kinds of French libraries: public libraries, departmental libraries, university libraries, national libraries, and so on. Of all of these, it was the territorial libraries (that is to say public and departmental libraries), which carried out the majority of the actions identified in our survey (56%). Despite this evidence, we cannot conclude that public libraries have been more active than academic libraries. Indeed, 116 libraries or organizations appeared in this survey, each with one or several actions to their credit. Relative to the number of libraries in France, the mobilization can seem insignificant; however, only libraries that publicized their actions on the Internet, or employed librarians who were part of the network of this article's author, were able to be observed in the study. It should be noted, however, that nearly a third of all academic libraries in France publicized their actions.

In the case of public libraries, the proportion is significantly higher, that is to say 0.43% of the libraries and reading stations counted by the in 2011. This extremely small percentage can be explained by the fact that public libraries are less active on the Internet and social media than academic libraries. Moreover, in order to know the actual number of actions carried out in reality, we would have had to contact France's 16,000 public libraries and reading stations identified by the government. As we were unable to undertake such an enormous project at the time, we had to limit ourselves to studying the actions that were diffused, publicized, and politically positioned in full view of the public, adding a second political level to an already politicized action.

The actions we observed were carried out by libraries through all of France, both in small towns (with 500 habitants or fewer) and larger cities such as Paris, Lyon, and Lille. Paris, the city directly affected by the shootings, was not the only city to react, and the mobilization in the wake of the attacks clearly reached far beyond the geographical context of the attacks. We have yet to determine whether the common point between these institutions is: their status as an institution dedicated to information, or their status as a French institution. In other words, should these actions be qualified as the actions of citizens or libraries? It is worth noting that in the smallest villages in the study, the library personnel was often entirely composed of volunteers, a fact which renders the status of the library as a public institution (within the context of the Action / Type of Library actions carried out) and the obligation to uphold neutrality as completely separate from the staff. As is evident in the above chart, the information on the actions was most often attained through the library's website 7 (77 times) and social media pages 8 (72). The other sources, which reflected direct experience or first-hand accounts, were less frequent; nevertheless, we continue to observe the latter. Putting these actions online shows that they are not hidden under the cover of a neutrality injunction, but on the contrary, very much in the public eye. It should be noted, however, that because this survey was not exhaustive, we were unable to examine the absence of action in detail, or distinguish the libraries which publicized their actions from those which did not act at all. In other words, that which was unobservable was not considered as an active stance, but as the absence of a stance, that it to say a position which was not entirely in line with the reactions of local and national governments, nor in the general reaction of the French people. This brought us to wonder if neutrality is in fact a question of quantity: perhaps the more visible reactions there are, the less the object of the reaction can be neutral.

Finally, the categorization of actions by type shows a significant proportion of messages and document selections. The actions were carried out between January 7 th , 2015 and December of the same year, even if the large majority were carried out that January (159 out of 187). This demonstrates both the quick reflexes of France's libraries, which went into action from the day of the attacks, and the gravity of the event which, 12 months later, continues to inspire specific actions.

Typologie des actions

The combined analysis of type and time of action allowed us to distinguish three distinct phases: a period of high emotions during the first month after the attacks, a period of transmission during the first quarter of 2015, and finally a period of transformation which lasted for the duration of the year 2015.

2B: Results and Discussion

2B-1: Emotion

The month of January was an emotional one due to the attacks. This emotion was evident in the messages diffused by libraries (73 out of 187), calls for collective action (3) and spaces dedicated to free speech available to the public (7). The total number of actions carried out in January represent 45% of the total actions observed in the study. The messages that were diffused expressed condolences and support for the victims' families, paid homage to the victims, and reaffirmed the determination of France's libraries to support freedom of speech. Public walls dedicated to free speech also served as spaces for the expression of thoughts for the victims, their own worries, or other responses to the attacks. "They wanted to bring us to our knees, but they've made France rise up" was written by two students in Caen on the wall dedicated to free expression in their university library. Furthermore, actions that focused on solidarity, rather than liberty or vivre-ensemble, represent 48% of the total actions, of which 61% expressed solidarity with the victims and 39% with Charlie Hebdo. Finally, the Je suis Charlie sign was posted in library windows where it was visible to passerby, on the walls and windows inside the libraries, and sometimes even posted on the librarians themselves. In the library of Lyon 1 University, for example, the staff wore Je suis Charlie armbands. 52% of the total actions in the study, all categories included, included the message Je suis Charlie, whether in the form of a photo, a title, or in the URL of the messages broadcasting the action.

These messages, and above all the Je suis Charlie posters, cannot be considered neutral for two reasons: on one hand, in posting these messages, the library takes a stance on a current event, on the other hand, the Je suis Charlie posters elevate a slogan which does not represent all French citizens, when state institutions are supposed to avoid making distinctions between citizens. This emotional reaction, as understandable as it is, demonstrates that these librarians reacted as citizens rather than civil servants, taking a certain distance from the events and the conflicts which mark, and even underlie our society. Does this mean that this lack of distance is acceptable in times of crisis, and that the library must therefore take a side in the issue? Or must we distinguish between messages diffused by the libraries and, much less frequent, invitations to expression such as walls dedicated to free expression and calls to rally?

Though some say that this expression of the library, and by extension, the public institution, is a renouncement of its neutrality, others evoke the notion of each individual's freedom to express their opinion in a public institution, a space which precisely because of its duty to neutrality guarantees freedom of expression, or in other words, is a public space. As Sandra Salomon reminds us, Hannah « Arendt defined politics as courage and speech: the kind of free speech that can only exist in a public space where a plurality of free men (citizens) can exchange diverse ideas in free confrontation (the Athenian democratic model, the Greek ecclesia)." (Salomon, sd). Thus, we can say that the messages and posters reflect the reaction to current events, whereas walls dedicated to freedom of expression and calls to rally consist of a veritable political action in support of democracy, without upholding the neutrality of the institution.

2B-2: Transmission

During the first two months of 2015, we observed a second type of action, which was more focused on the transmission of information: selections of documents (50 actions), acquisitions (8) and expositions ( 26). This second wave of actions was more specifically library-oriented, and, we can suppose, more neutral due to the cover of professional expertise. These actions often reflected the effort of librarians to contextualize, explain, show, and put into perspective the events of January 2015, and represent 44% of the total actions observed. Librarians' selections also dealt with the themes of freedom of expression, censorship and religion, as well as homages to victims through exhibitions of their work. The selections of books, audio and video sources, songs, and electronic documentation were diffused on all types of media and materials: on the windows and tables inside libraries, via links on their blogs and websites, through thematic pre-selections in their catalogues, and so on. Sometimes these selections were explicitly directed toward parents, as when Tourcoing public library offered a selection of digital resources on talking about traumatic events with children. Acquisitions mostly consisted of renewed subscriptions to Charlie Hebdo when the publication of the magazine was temporarily halted, or the purchase of the first issue after the attacks. The Pierre Villey sound library, for example, offered free access to the audio description of the January 14 th issue. With regard to exhibitions, libraries often displayed covers of past issues of Charlie Hebdo, or illustrations drawn by journalists from all over the world. The Hérouville library, for example, displayed drawings that were paired with excerpts from both the UNESCO Manifesto for Public Libraries and the Universal Declaration of Human Rights.

These actions test the neutrality of libraries, not in reaction to the attacks, but leading up to them. Indeed, in order to foster freedom of expression, there must be many different collections that offer a real sense of neutrality with regard to the construction of the collection. This neutrality, though a myth, doesn't prevent librarians from trying to reach this goal as much as possible -but the acquisitions of Charlie Hebdo issues, or the renewal of subscriptions to the magazine, show that this kind of pluralism is far from being reached. We hypothesize that this pluralism is avoided due to the potential conflicts it could create, conflicts that librarians may not know how to mediate. The Champs Libres library, for example, posted a reminder of the constitutional pluralism of democracy, and filled their shelves with documents as disparate as Charlie Hebdo, Minute and Monde Libertaire. The reaction of some of the public was virulent: tracts, protests, and so on denounced the presence of extreme-right literature in a library.

This question of conflict also arose during the third period observed in the study, with the organization of debates. At a moment when the key concepts of the French republic such as laïcité, vivre-ensemble and freedom of expression were being re-examined, few debates were held. Though some were organized later in the year, this trend nevertheless raises the question of the place of contentious topics in state institutions.

After displaying a Je suis Charlie poster, one library director offered to organize a debate centered around religion -the mayor, however, reminded her that "here, we don't discuss politics", the implication being that anything which leads to conflict and debate is inherently political, while actions that lead to consensus are inherently social, in the sense that social ties are rediscovered and reaffirmed.

It is here that we can further question the issue. Should the library be a reflection of these social links, specifically those which unite, or should it, as Anne Kupiec wrote (1999) "serve as a reflection of divergences and conflicts, borne of social divisions, that occur in democratic societies. The library brings to light the tensions and differences of opinion that come with vivre-ensemble: democracy is not synonymous with general and perpetual consensus". In other words, embracing conflict allows us to better examine neutrality, and divorce it from the definition that depoliticizes librarians, moving it closer to the exercise of a plural and critical examination of society and the evolution of democracy (Lewis, 2008). By thus renewing the democratic debate of ideas, and we can consider that democracy does not come about when we agree, but when we confront ideas head on. As Chantal Mouffe wrote: "A democratic government must establish institutions which allow conflict, not in the form of a confrontation between enemies, but in a form that I call "agonistic": a confrontation between adversaries who know that there can be no rational solution to their conflict, but recognize their opponent's right to defend their point of view" [START_REF] Mouffe | Mais à quoi servent vraiment les bibliothèques municipales ?[END_REF].

2B-3: Transformation

The final period was observed over the course of the year 2016, and was most reflective of a transformation which manifested itself in a renewal of debates, as well as a particular attention given to reflection, discussion and training. This transformation took on a double form: first, that of debates and conferences that were open to the public, and second, day-workshops, articles, and training programs for professionals. Admittedly, these statistics are rather low: we observed 11 out of 187 actions directed towards professionals, and 8 actions that can be qualified as public debates. However, these low numbers should take timing of the actions into account. These actions did not take place during times of high emotion, but over the course of the entire year, continuing even into 2016. This was thus a period of fewer actions, but these actions were carried out after more thorough reflection and consideration.

Thus, the Lyon public library published a message of solidarity, and put Charlie Hebdo covers on display in several locations in the days following the attacks. Soon after these messages and images were posted, the windows of one library were vandalized. This even prompted a city-wide meeting of all public library personnel in January, which was organized in order to exchange information and prompt discussion. This internal discussion preceded several actions that wouldn't occur until June or even autumn of 2015, such as conferences on the caricature, workshops examining caricatures of former presidents, and the launch of the Democracy project9 . Similarly, starting in February, the Dunkerque public library suggested that patrons leave a hand-written commentary on the books that they returned, hoping to respond to the attacks by recreating the social ties both within and without the library. Finally, the departmental library of Pierres-Vives in Montpellier temporarily emptied its shelves of documents in order to help patrons visualize the consequences of censorship, and provoke discussion and debate.

While this was not the first time that debates on freedom of expression or religion were organized by libraries, for many it was perhaps the first time that they touched on these kinds of themes, as libraries are often hesitant to broach subjects that can create conflict. Similarly, with regard to professionals, we can take the example of the Champs-Libres library, which organized a series of workshops for their staff on the reflection and discussion of the neutrality of public institution, and the pluralism of the library's collections. What interests us here is the willingness of libraries to offer themselves up as spaces dedicated to transformation -or, at the very least, reflection -on the transformation of society, notably questioning key notions of our republic and democracy. It's the idea of neutrality, exercised by librarians through their engagement in a political mission, that is being questioned. While we have no trouble recognizing the militancy of the generation of the 70s and 80s, which fought for the institutionalization of libraries, and defended the book and public reading, we also consider a militancy which advocates issues that are less centered around libraries (feminism, ecology, LGBT militancy, anti-racism, and so on) to be non-neutral. This kind of delayed militancy was amplified in 2015 by the attacks and incoming refugees.

En 2005, Dominique Lahary painted a picture of the different generations of librarians, and found the most recent to be the most depoliticized:

"[Dominique Lahary] proposed a delineation from which arise four kinds of professionals. The oldest are mostly militants and creators. Those in their 50s also show these tendencies, but are primarily concerned with implementing a republican approach to public reading, cultural exchange, and taking a normative approach to the profession and the tools that come with it. Those in their 40s have had managerial training, and have a different, more political vision of the profession (the state vs. local authorities). Finally, the youngest generation is distancing itself from a centralizing approach to the role of the book, and are better trained in new technologies; they are more "counselors" than prescribers, committing themselves to the needs of the patron, and using a more relativistic cultural approach." (Verry-Jolivet, 2005) Perhaps we should see this last generation not as depoliticized, but as a generation that has shifted the object of its politicization, and in this time of crisis has finally found a way to express this politicization through action, notably library-related actions. One text, presented at a conference on emotions and politics, thus explains between professional careers and political engagement [START_REF] Arrigoni | Les sensibilités primordiales, un lien impensé entre carrières professionnelles et carrières militantes[END_REF]. Indeed, militancy naturally takes a form that is driven by the combination of skills and knowledge that are often developed in the professional world, a combination which also serves to legitimize the militant action being carried out. In fact, an analysis of the actions by theme reveals a silence on the subject of religion, with freedom of religion representing only 2% of the themes addressed by these actions, while the freedom of the press represents 24%, and freedom of expression, the concept at the heart of library activity, and the foundation of the library itself, represents 74% of these actions. Furthermore, the aforementioned emotion present during the first period in this chronology could be the catalyst for political engagement [START_REF] Fontaine | Les Instituteurs en Résistance. Obéissance collective et désobéissances individuelles au prisme de l'émotion[END_REF] which relies to a certain extent on professional practices, but which focuses on subjects linked to politics in general, rather than the book policy in particular.

Conclusion

This study on the actions carried out in the wake of the attacks of January 2015, which was conducted with the question of neutrality with regard to librarians in mind, allowed us to witness a revival of the question of politics in libraries. In raising this question, these libraries have blurred the line between the political and the social, and revived democratic debate, and begun to think of themselves not as emancipators, but as a participants. We hypothesize that we are witnessing a turning point in the construction of a new model of the French library, in which the role of the institution is not to passively defend the democracy we have, but to actively construct the democracy we want. To this end, librarians perhaps need the appropriate training and education, not just managerial, but political: training in political culture, training on the values of libraries, and training in critical thinking.

Figure 1 :

 1 Figure 1: Actions, categorized by type of library.

Figure 2 :

 2 Figure 2: Means by which the action was communicated.

Figure 3 :

 3 Figure 3: Type of action.

The word laïcité is so inextricably linked with French history that there is no equivalent in the English language. This word refers to the law of laïcité, which followed the separation of church and state in 1905. This law, which is absolutely fundamental to the French republic, requires religious neutrality on the part of the state and public services. Government employees, for example, cannot display their religious beliefs while on the job, whether physically or verbally, whether through actions or the passive wearing of religious garments and jewelry. According to the law, citizens are free to practice the religion of their choice, and wear signs and symbols of their religion, everywhere but in public schools, where children are forbidden from wearing religious garments or paraphernalia in the interest of avoiding discrimination. Furthermore, religion is considered a private practice, which should therefore not be practiced in public spaces.

The notion of vivre ensemble (with or without a hyphen) is related to the construction of the French nation. How can individuals share a territory and a collective vision, all the while maintaining their own individuality with regard to religion, opinions, and ideas? Since 2015, many appeals have been made to this concept, whether as positive reminders of the capacity of the French state to offer a rule of law that is based on the notions of liberty, equality and fraternity, or as critiques on the notion of vivre ensemble, which was challenged, or at the very least disturbed, by the different attacks carried out on French soil, as well as the responses by the state in the wake of the attacks (such as the declaration of a state of emergency).

My sincere thanks to Nathalie Clot for asking me to proofread and edit her translation of David Lanes's text, which led to our launch the first step of the #bibenaction survey together. Thank you for the opportunity to transform my feelings of powerlessness into something positive.

Either within the framework of parallel collection (Dominique Lahary and Philippe Charrier), or within the framework of personal contacts.

Thanks to Marie Larochelle for creating a unified Excel spreadsheet which improved upon my original document.

This project aimed to organize a cultural season (2016-2017) centered around democracy that would have a very strong participatory element, both internally with the teams organizing the event, and externally with the public.


Study and Development of Silicon Carbide Stray Light Optical Components for Third Generation Gravitational

Wave Detectors R. NAHED 1,2 ; O. DALVERNY 1 ; A. CHIUMMO 3 ; M. FERRATO 2

• BOOSTEC® SiC could be a good candidate for baffles for the third generation gravitational wave detectors regarding its thermal and mechanical properties.

• MERSEN SiC-CVD is a very promising material for this purpose due to its agreement with the optical requirements desired.

• Preliminary results of FE modeling interaction between the test mass and the baffle allowing us to study and analyze their temperature variation .

Problematic and research objectives

Conclusion & Next Steps

The chamber and the core optics with stray light

Methodology of simulation

Candidate

Requirements

SS 304

Al-NiPW SiC-CVD SiC

Low Scattering •(RT) •• ••• • High Laser Induced Damage Threshold LIDT ••(RT) ••• ••• High Thermal Conductivity • ••• ••• ••• Low Thermal Expansion •• • ••• ••• High Stifness •• • ••• ••• High Absorption Coefficient • ••• ••• •• ••• Most promising candidate Physical characterization of BOOSTEC® SiC (a) (b)
• Material Requirement (SiC is a very promising candidate)

• Optical Characterization

• Measuring the scattering at room temperature (Advanced VIRGO) and at cryogenic temperature (Einstein Telescope ET)

• Same conditions for measuring the reflectivity of SiC • of the thermal and thermomechanical changes induced by scattering light flux,

• Analysis of the influence of this changes on the scattering light process (if needed).

All the methodology could be applied to advanced virgo and/or third generation interferometer.

Key points : cryogenic temperature, high laser power density Stray light in the current detectors is being reduced using light shades called « baffles ». In fact, the third generation detector will be using a very high power laser and the test masses will be subjected to a different temperature condition « cryogenic temperature ». Hence, we had to find a new material that can be a replacement for the current baffles and thet can bear these conditions.

Optical characterization of 3 samples of MERSEN SiC

Mechanical field

• TIS is calculated as the ratio between scattered output light and input light source

• Studying the characterization process of BOOSTEC® SiC under cryogenic temperature to explore whether the optical requirements are achieved.

• FE Studies of the thermal analysis of the conduction process.

• Mechanical analysis under room and cryogenic temperature of SiC setup must be explored to evaluate displacement, stress; strain and analyze mechanical behavior.

• Evaluating the possibility of using different types of coatings with the same substrate SiC. This activity is supported by the European Commission, through Marie Curie Actions, GraWIToN Project

Conclusion Next Steps

Fig:

  Fig: BOOSTEC® SiC experimental data as a function of the temperature, (a) thermal conductivity, (b) thermal expansion.

1•

  Université de Toulouse; INP/ENIT; LGP ; Tarbes -LGP. 47, avenue d'Azereix -BP 1629, 65016 Tarbes Cedex, France 2 MERSEN BOOSTEC-zone industrielle-65460-Bazet; France ³ EGO; Advance VIRGO; Cascina (PI), Italy * E-mail: rudy.nahed@enit.fr Optical characterization of the most promising materials (SiC, coated SiC…),

••

  Fig: Temperature field over the baffle and the mirror with room temperature as surrounding one (K)

•

  Maximum temperature attained by SiC at room temperature is T = 297.8 K • Maximum temperature attained by SiC at cryogenic temperature is T = 141.2 K • Temperature variation at room temperature and cryogenic temperature is E! = F G