Jeanne Fagnani

Equal access to quality care: Lessons from France on providing high quality and affordable early childhood education and care

Along with the Nordic countries, France leads the European Union in public childcare provision and benefits aimed at reducing child care costs for families. It has also

widely been recognised that the French childcare system has many strengths (OECD, 2012). In recent years, however, in the context of economic uncertainties, policy makers have been confronted with new tensions and dilemmas. While France has continued over the last decade to progressively consolidate and enhance its promotion of policies to support the work/family life balance, the introduction of new laws in the domain of early childhood education and care (ECEC) has mirrored the growing hold of employment policies over childcare policies.

What has been at stake when it comes to accessible, affordable and good quality ECEC? To which extent the system is meeting the challenge of providing equal access for all children aged under-six? What were the rationales underpinning changes and what were the key drivers of change? Against the background of budgetary constraints, what are currently the main priorities? What is the impact of the rising demand of formal childcare provisions on quality framework and tools?

These are the questions addressed in this paper.

The first part of the chapter will be devoted to the ECEC system. I will in particular investigate whether socio-economically disadvantaged children are accessing high quality ECEC to the same extent as their more advantaged peers. Funding and cost of care to families will follow. Then I will focus on the quality issue and the recent decisions made in this domain. To conclude I will highlight some of the challenges policy makers currently face and the tensions they have to deal with.

A note on terminology: for the rest of the chapter I will be using early childhood education and care as well as other terms, such as crèches, childminders, écoles maternelles (nursery schools), Multi-accueil, (multi-functional childcare centres), which more aptly describe the services available in France, as the chapter will make clear.

1.An extensive and segmented system of public provision: day care and écoles maternelles France has a well-established and long-standing early childhood system dating back to the end of the 19 th century. The system has two tiers falling under separate ministerial auspices: formal childcare provisions --publicly-subsidised centre-based and home-based arrangementson one hand and écoles maternelles on the other hand. This dual system is a legacy of the past.

As Table 1 illustrates, the services available depend on the age of the child. While almost all children aged three to six are enrolled in écoles maternelles, which are free and fully integrated in the school system, the system of services for children under three is more varied and coverage rate is lower. For this reason, in this section I will put emphasis on children below three years. The French childcare system is based on the principle of universality and the rationale underlying this system is to provide equal access to all public facilities whatever the income or the social background of the family; this means that crèches are not targeted at low-income families. However, lone mothers in employment or registered as unemployed are frequently given priority, in particular in disadvantaged areas. Indeed, there is a consensus among policy-makers and public opinion that the best way to lift families and their children out of poverty is to help the mother to sustain employment.

Although formal childcare provisions (crèches and childminders) are highly subsidised and fees are income-related, for low-income families these services remain expensive. Indeed, almost all children from the lowest income families are cared for mainly by their parents (Table 3). For working parents this means coordinating so that working schedules do not overlap. Among low income families, the take-up rate of the parental leave benefit is much higher than among better-off families (Boyer, 2012). This flat-rate benefit (€ 566 per month if the parent stops working) can be provided until the child reaches the age of three. In 2009, 61 per cent of low qualified mothers compared to 22 per cent of highly qualified mothers claimed this benefit (Boyer, 2012).

Besides differences in ECEC usage across income levels, it is worth noting that there are large geographical disparities in the supply of places in centre-based provisions [START_REF] Borderies | L'offre d'accueil des jeunes enfants de moins de 3 ans en 2010, Paris[END_REF]. In deprived areas, often located in the outer suburbs, if parents cannot get a place in those centres mothers are therefore prone to stop seeking work or to be in employment.

Centre-based provision: crèches and multi-accueil

Nearly 15% of all children under three attend centre-based services, which take mainly the form of crèches collectives, open up to 11 hours a day all year round.

Over the last decade, there has been an increase in the number of multi-centres Cooperating with local authorities and CAFs, companies can also contribute to the setting-up and running costs of public centre-based services (including around-theclock home-based childcare) and in exchange some places are reserved for their employees" children.

In disadvantaged areas1 , over the last decade, the government and the CNAF made important efforts to increase access to collective childcare settings. One of the main objectives of the national programme "Plan Crèches Espoir Banlieues' (literally:

"project childcare hope in disadvantaged areas") is to encourage the creation of "innovative" and "flexible" childcare places suitable for parents with non-standard working schedules. The programme, however, does not mean that children from the most deprived families have systematically priority access to day care centres for under-threes because the system remains based on the principle of universality and one of the criteria of the choices (among candidates on the waiting list) made by the local council is to mix children from diverse social backgrounds.

Importantly, crèches are highly valued by families, as a result of the staff"s qualification requirements in place (see below) and of the prevalent idea that crèches provide an "ideal" preparation for the transition to nursery school and consequently to primary education. Therefore the demand emanating from middle-class families is high. The early socialization (a longstanding tradition in France dating back to the end of the nineteenth century) this provides is held in high esteem, and the probability that a child will attend a crèche increases significantly when his or her mother has reached a high level of educational attainment. 21 per cent of those children whose parents are in senior or middle management or occupying supervisory roles are enrolled in a crèche as their main childcare during the week, compared with only 5 per cent of children from working-class families [START_REF] Ananian | Modes de garde et d'accueil des enfants en 2007[END_REF]. Table 3 also shows that children living in the wealthiest families are overrepresented in childcare centres.

Registered childminders: a major contribution to the supply of childcare services

Since the nineties, the primary method for bridging the gap between supply and demand for childcare has been to increase government support for licensed child minders who look after children in their private home.2 By 2010, the number of childminders looking after children reached 306 256 (including 1 434 men).They are required to register with local authorities, a procedure that is mandatory if parents who rely on them wish to be eligible for the related childcare allowance paid by the local CAF and the tax deduction.

When both parents work full-time, childminders are the main and primary form of care arrangement for under-threes: 37% are looked after by a childminder. The same is true for the whole population of children looked after in any formal care arrangement (Table 2).

Some registered childminders are directly employed by municipalities or by NGOs (termed crèches familiales). In rural areas, some local authorities have developed micro crèches, where childminders look after children in a collective place, mixing individual childcare by childminders and collective care.

In socio-economically deprived areas, low qualified women are being encouraged to become childminders, both to increase the supply of places in formal childcare and to support women"s employment. A counsellor of the local employment agency advises them and they may be provided with a financial support from the CAF to help them adapt their home to regulatory requirements.

Working parents can also hire a baby-sitter or a nanny to look after their children either on a full-time basis or to provide after-school care and to cover Wednesdays.

Provided that he/she is declared, a childcare allowance covers part of the social security contributions that must be paid by these families. In addition, they may deduct 50%, up to €6,000 per year, of the real costs from their income tax. However, only a few parents can afford this care arrangement (Table 3). Over the last decade, policies targeted to children from disadvantaged backgrounds have channelled additional resources towards schools located in more deprived

areas. An area is designated as a Zone d'éducation prioritaire (ZEP), "priority education areas", when it includes a high proportion of those children, defined according to a variety of criteria outlined by the national Ministry of Education. The government passed a law in 2005 to encourage and extend in these areas access of under-threes to école maternelle by providing them with priority access. In schools with many two-year-olds, there may be a toute petite section (very little section) or children may be integrated with the three-to-five year olds. Child/staff ratio is most often falling to 20 children plus an assistant and is capped at 25.

The shortfall of places in crèches, and the fact that this service is free, has given parents living in ZEPs a strong incentive to ask for a place in a nursery school.

However, the share of children aged between two and three in écoles maternelles has fallen off sharply from 37% in 2000 to 11.6% in 2011. This is mainly due to the dramatic increase in the number of children aged between three and six (following a growth in fertility rate since 1999) who are given priority over the two year olds and to funding restrictions at the national ministry of Education (resulting in the reduction in the number of teachers and assistants). On the other hand the enrolment of twoyear-olds remains a controversial issue: some children"s experts underline that école maternelle is not appropriate to the needs of under-threes 3 while some research shows the benefits of early schooling for children from economically disadvantaged backgrounds.

It is important to note, however, that most of the under-threes attend school only in the morning [START_REF] Vanovermeir | L'accueil des jeunes enfants : axe majeur de la politique familiale française depuis les années 1970, Paris, Dossier Solidarité Santé[END_REF].

Funding structures: the state, the CAFs, and local authorities

Funding structures are very complex and vary according to the type of care Employers are involved in an indirect way in funding childcare because CNAF is mainly funded out of social security contributions paid by employers (around 65%).

The state, through income tax and other taxes, is the other contributor.

Local authorities (départements and municipalities, also named communes) also make a significant financial commitment (Boyer, 2012). They have however substantial autonomy in offering crèches and EAJE in general: they are not required to create childcare facilities and sometimes prefer to encourage and help women to become childminders (through the funding of training programmes) because it is much less expensive for them than to develop day care centres. This partly explains why there is a substantial variation in crèches enrolment rates across the country.

Local authorities also fund part of the running costs of nursery schools but teachers" wages are paid by the national ministry of Education.

In regard to collective childcare settings, the rules that govern the levels of public funding (by the State and the CNAF), and the levels of (income-related) fees to be paid by the parents are set up nationally following guidelines fixed through agreements signed every four years between the government and the CNAF. The cost of childcare to parents depend on the type of care arrangement chosen, the number and ages of children, and the income level. Indeed for all forms of subsidized childcare provision (outside écoles maternelles which are free) parents pay on a sliding scale according to their income.

Childminding is subsidised both by the state and by the CAFs. The state allows tax deductions from income tax, up to a limit of €1,150 per year, and offers tax credits for families who are not liable to income tax. The CAFs, on the other hand, subsidise childminding through an allowance ("Complément de libre choix du mode de garde'-CLMG; literally: supplement for the freedom of choice of the child care arrangement)5 .

The CLMG covers the social security contributions to be paid by the employer of the registered childminder, and also provides the family with an additional and incomerelated financial contribution. The amount of this allowance also varies according to the age of the child (less than 3, and 3 to 6) and the number of children living in the family.

In order to be eligible to receive the allowance, parents must pay the childminder at least the statutory minimum income6 defined by the CNAF to be eligible for the CLMG: €46.10 per child and per day corresponding to 10 hours of care for the child7

(the net median wage per hour and per child was €2.96 by 2010 and the net average wage per hour and per child €3.03) [START_REF] Fagnani | Des assistantes maternelles mieux formées et plus qualifiées. Les parents consentiraient-ils à augmenter la rémunération ?" (Better trained and more qualified childminders[END_REF].

In 2004 a significant increase in the allowance that low-income families receive made childminding more accessible than it was. However, for most of them, it remains however too expensive and in 2007 only 4% of the families with income below 1,100 euros per month could afford a childminder to care for their child aged below three compared to 22% of the families whose income was between 1,100 and 1,700 euros and 37% of the families earning more than 2,300 euros [START_REF] Borderies | L'offre d'accueil des jeunes enfants de moins de 3 ans en 2010, Paris[END_REF]) (see also

Table 3).

As far as crèches are concerned, parents pay on a sliding scale according to their income. The cost of a place in a crèche also depends on the number of hours of attendance. For instance, in a family with a single child cared for 9 hours a day and 18 days per month, net out-of-pocket expenses amounts to an average of €400 per month to parents with an income-level of €5,471 and more while for an income-level of €2,163 this amount represents €100 per month (Boyer, 2012).

For low-income families, despite the related childcare allowance (CLMG), the cost of a childminder is twice the cost of a place in a crèche. The shortage of places in crèches is therefore detrimental to them, in particular to lone parent households, and presents a barrier to full-time work. Consequently when they are in employment they most often rely on relatives or to undeclared childminders.

3.Quality of provision and the current regulatory framework

PMI services: a crucial role in ensuring quality

The national public system of preventive health care and health promotion for all mothers and children from birth through age six (Protection Maternelle et Infantile -PMI) plays a crucial role and are responsible for upholding the quality of public childcare provision (childcare centres as well as licensed childminders). Created in 1945 and subsequently developed [START_REF] Fagnani | Family Policy in France, International Encyclopedia of Social Policy[END_REF] local PMI services fall under the remit of the départements (local authorities) and are supervised by the national ministry of social affairs (the department of social security).

Local PMI are in charge of licensing and monitoring all care services which fall outside the remit of the public school system and intervene regularly across many areas. Primarily, they ensure that providers (including child care centres run by private providers but publicly subsidised) abide with regulation concerning health and safety (including preventive health exams and vaccinations), nutrition and staffing standards. Doctors or puéricultrices employed by the PMI services regularly inspect services..

Health services are also integrated in ècoles maternelles: they have a doctor and psychologist on their staff several hours per week or available for consultation as needed to provide evaluations and referrals. Preventive health exams are mandated for all four year-olds. Trained medical staff from the local PMI services also play a role in helping integrate children with special needs, whether in schools or childcare settings.

Policy priorities, goals and requirements affecting childcare provision

There is a different understanding of quality in nursery schools and in services for under-threes. This reflects the dual nature of the system of services. In relation to all publicly subsidised childcare services (except "nannies" or home helpers) the policy priorities and goals can be summarised as follows:

-Ensuring children with safety, health, and a sense of well-being by focusing on education, socialisation, and cognitive development -Giving parents a "freedom of choice" over childcare arrangements -Enabling parents (in particular mothers) to participate in the workforce -Enhancing equal opportunities for children -Complying with the principle of social justice (income-related fees in childcare settings)

-Encouraging social mix that underpins social cohesion.

It is assumed that child care centres can partly offset the negative outcomes for children living in families coping with hard living conditions (in particular overcrowded housing). But against the background of high unemployment rate, there is also an underlying rationale: creating a tool to fight unemployment by encouraging parents to hire someone to look after their children (licensed childminders and nannies).

Within this overall approach, different services have their specific quality regulatory framework, which is legally enforceable.

. In crèches, staffing standards are laid down nationally: 1 adult to 5 children who are not yet walking; and 1 to 8 for other children. To ensure psychology wellbeing, each child is under the specific supervision of a "personne de référence" (contact person).

Although there is no national curriculum for collective childcare settings, since 2000 crèches and Multi-accueil have been required to elaborate an "Education and social project" (Projet d'établissement) that includes a Projet éducatif (Education programme) and a Projet social (Social project). The main goals embedded in the quality tools are: enhancement of cognitive and physical abilities, development of pedagogical activities, respect for biological rhythms, ensuring children with safety, health and child well-being, promoting and favouring social integration (see above).

Parents are also encouraged to participate in the everyday life of the setting.

Emphasis is also put on the exchanges with stakeholders involved in childcare policies, as well as on coordination with different agencies.

Other objectives include enhancing equal opportunities for children, thereby contributing to prevent social exclusion and to foster gender equality by supporting mothers" participation in the labour market. Despite these significant improvements, childhood experts and childminders" trade union, however, still point out the persistent shortcomings and the heterogeneity of the training programmes across the country and call for a further development of qualifications available to childminders [START_REF] Fagnani | Des assistantes maternelles mieux formées et plus qualifiées. Les parents consentiraient-ils à augmenter la rémunération ?" (Better trained and more qualified childminders[END_REF]. However, parents cannot always afford to rely on a qualified childminder despite generous childcare allowances: such a person can be more demanding in this regard than a less trained counterpart.

In order to enhance early socialisation of children, childminders are encouraged to participate in childminders centres (Relais assistants maternels -RAM) where they can exchange on their own experience with other childminders and also receive advice from a qualified child nurse, while children can participate in collective activities. RAMs are highly valued by childminders [START_REF] Fagnani | Des assistantes maternelles mieux formées et plus qualifiées. Les parents consentiraient-ils à augmenter la rémunération ?" (Better trained and more qualified childminders[END_REF] but despite their rapid increase over the last years (the numbers currently reach 500), there is still a lack of these facilities.

In 2005 childminders" employment regulation were revised. The aim was both to enhance the quality of care by improving working conditions and to make this profession more attractive through stricter regulation. Such regulation made childminders" employment contract more in line with that of other employees. The objective of the reform was to make work regulations closer to the common work rules, especially with regard to the labour contract, to earnings and working time regulations. The "professionalization" programme renewed childminders" collective agreement, thus settling labour relations between employers (parents, municipalities, NGOs) and the childminders. The national employment contract is binding, defines minimum payments (see above) and limits the legal working time. Childminders" salary should be paid monthly in order to provide childminders with regular earnings all over the year as well as entitlement for an annual paid leave. Finally, childminders became entitled to tax breaks on part of their earnings.

Staff qualifications and training programmes

Compared with childminders, staff in crèches (including in private crèches and in crèches d'entreprise subsidized by the CAFs) and Multi-accueil are well-trained, closely supervised and relatively well-remunerated (compared to the childminders).

There are three categories of staff of workers. First, the puéricultrice (pediatric nurse)

with four year post-secondary education. The puéricultrice usually works as the director of a crèche and Multi-accueil. But the director may also be doctor or midwife. It generally includes studies in education; philosophy; history of education; sociology;

psychology; subject study and preparation for administrative tasks.

To help teachers with daily activities such as clean-up and toileting as well as in carrying out pedagogical activities, assistants named as ATSEM (Agent territorial spécialisé des écoles maternelles) are employed by local authorities. Since 1992, ATSEM are required to hold a certificate in early childhood education (CAP Petite enfance), a professional qualification level accessible from the age of 16 without being required to have any diploma. These aides are appointed by the mayor and work under the supervision of the director of the school.

In écoles maternelles there are no national regulations for staff-child ratios. In 2010-2011, there was on average one teacher to every 25.7 children. The assistants, ATSEM, are not included in this calculation because not all local authorities fund enough assistants, especially with the other children, and moreover they are not present the whole day.

Tensions and inconsistencies

French childcare policy is currently facing new challenges linked to the numerous and dramatic changes which have occurred both on the labour market and in the family sphere. Policy makers have therefore to deal with tensions and difficult trade offs. In a context where their room of manoeuvre is limited, ensuring high quality provision seems at odds with affordability and availability of places for under-threes. How to reconcile children"s interests with other interests, e.g. gender equality, employment and employers? Alongside some progress it is clear that reforms recently introduced appear to be driven more by labour market pressure and mothers" rights to paid work than always couched in terms of the "best interests" of the child.

Indeed, over the last decade the ministry in charge of family policies, local authorities and the CNAF, have refocused their energies and currently place more emphasis than before on the following issues: how to increase the number of available slots in the formal childcare sector (in response to the rise in the number of births and the need for many women to be in paid employment) and enable parents confronted with non standard or family-unfriendly flexible work hours to combine their job with family responsibilities [START_REF] Fagnani | Childcare Policies in France: the Influence of Organizational Changes in the Workplace[END_REF] and at the same time how to promote female employment in economically disadvantaged neighbourhoods.

4.1.Tensions between quality of care and a shortfall of places in crèches

Although measures were being taken over the last decade to compensate for a persistent shortfall in supply, policy makers have yet to satisfy the ceaseless demand for places in childcare facilities and the services of registered childminders8 . This problem has been aggravated by the difficulties local authorities and CAFs have to cope with in recruiting qualified staff (due to funding restrictions, there is a dearth of places in training centres for people looking to qualify for jobs in the childcare sector)

and thereby to reach the required standards imposed by PMI services (50 per cent at least of the staff in EAJE has to be made up of puéricultrice, éducatrice de jeunes enfants, auxiliaires de puéricultrice, nurses or psycho-motor therapists). This problem has also been reinforced by the fact that the number of children born in 2010 reached 833,000 representing a steady rise from the 757,000 reported in 1997. Moreover the enhancement of women"s employment has continued to be an explicit objective of French family policies [START_REF] Fagnani | France: Gender Equality, a Pipe Dream?[END_REF]. The increase in the number of places has therefore been given higher priority on the policy agenda. The results of a recent survey of local elected officials are indicative of this trend: over the last four years, 46% declared that they put at the forefront of their care policies the development of childcare places (CNAF, 2012).

Tensions between quality and affordability

The objective of the enhancement of women"s employmentin particular in disadvantaged areasdoes not always go hand in hand with an easy access to affordable childcare. And as far as registered childminders are concerned, the move towards their professionalization pushed up the price of this care arrangement. The increase in the amount of the CLMG, decided in 2004, did not fully offset this phenomenon. It is therefore detrimental to low income parents who are likely to be less demanding in terms of quality of care provided by childminders since demand far outstrips supply in childcare settings.

Concomitantly policy makers are once again confronted with another dilemma: taking into account the shortage of childminders in many urban areas, how to make more attractive this profession without increasing their earnings [START_REF] Himmelweit | The prospects for caring: economic theory and policy analysis[END_REF]? But against the background of budgetary constraints, will the parents be willing to pay more a better trained childminder? A recent research based on a representative sample of parents relying on a childminder shows that only around a third would be willing to pay more [START_REF] Fagnani | Des assistantes maternelles mieux formées et plus qualifiées. Les parents consentiraient-ils à augmenter la rémunération ?" (Better trained and more qualified childminders[END_REF].

Tensions between quality and the objective of meeting the needs of parents confronted with atypical working schedules

Along with the organisational changes at the workplace, staff in the sector childcare have been placed under pressure to adapt their own working hours to the needs of the increasing number of parents confronted with long and/or nonstandard working hours. Moreover a growing number of employees have a low degree of command over the scheduling of their work hours, in particular in low paying occupations. .

Taking into account their family obligations, individuals employed in the childcare sector are all striving to protect their own interests and are reluctant to submit to ever more flexible working schedules. Registered child minders, if they can afford to 9 , will often refuse to look after a child outside of standard working hours. The result is that young children are often cared for by a rotating cast of characters and institutions within the same day. This is particularly true when both parents have non-standard work schedules; or when the parent is living alone [START_REF] Bressé | La garde des enfants en dehors des plages horaires standard, Paris, Direction de la recherche, des études[END_REF].

Recent decisions made at the expense of quality in childcare provision

Against this background, the following decisions have been made over the last decade on how to relieve some of the tensions inherent in the current childcare policies.

New legislation was passed on June 2010 introducing significant reforms in the "Code de la santé publique" (Public health regulation). First, a decision was made to decrease from 50% to 40% the minimum share of staff required to qualify as skilled workers (puéricultrice, éducateur de jeune enfant, auxiliaire puéricultrice) in childcare centres. This decision was motivated by the fact that a shortage of skilled workers had been acting as a brake on the swifter development of such centres.

Second, citing the fact that many young children registered in childcare centres do not attend every day or on a full time basis , the government decided to raise the number of children these centres would be authorized to accept. From 2011, crèches with more than 40 slots are allowed to increase by 20% the number of children registered and attending the crèche (15% for crèches with less than 40 slots and 10% for those with less than 20 slots).

Third, since the law of 2009 was passed, instead of being limited to having only three children simultaneously under their care, registered childminders are now allowed up to four. The aim was to increase the number of places in childcare provision and to provide the childminders with the opportunity to earn more thereby making this job more attractive. However, in a survey of local officials [START_REF] Pillayre | Conditions d'attribution des agréments des assistants maternels, Paris, Direction de la recherche, des études[END_REF] based in 94 departments and responsible for the supervision of childminders, 69%

declare that this measure will result in less time devoted by childminders to each child, less opportunities to play with them and less availability to enhance their cognitive development. Almost one out of five underline the risk involved as far as security is concerned and insufficient space in the home for each child to be able to rest.

None of these decisions have passed without controversy and some trade-unions and associations have denounced them as threats to the quality of childcare10 . So far, the government has turned a deaf ear to these criticisms.

The ministry in charge of family affairs introduced a measure in 2004 to promote the creation of crèches in private companies (termed "crèches d'entreprise") by providing them with tax deductions along with partial funding from the CAFs. In the context of increasing commuting time, this type of solution can be detrimental to child wellbeing, as children would have to commute with their parents. Related to this, in an attempt to satisfy employers" demand for more atypical work hours the last decade has witnessed an increase in the number of childcare services and crèches operating 24 hours a day and 7 days a week in order to allow working parents to meet the demands placed upon them by employers. These company-run centres (partly funded by the CAFs, see above) are a response to the new realities of the workplace.

The need for extended childcare opening hours set to match is a shared one. The example of Renault (a leader in the French automotive industry) is emblematic of the new reality: since 2010 its employees have enjoyed access to childcare from 5:30 am to 10:30 pm and this clearly illustrates that the children of its employees are spending significant amounts of time in outside care and thereby in commuting11 .

Within the same approach, while the government supports the development of childcare centres in socio-economically disadvantaged areas (see above), strong emphasis is put on the promotion of opening hours that are more in tune with "the needs of working parents" and on the development of so-called "flexible" and "innovative" child care arrangements. Operating hours of the childcare centres have been extended to over 10 hours per day, exceeding the current regulations granting children the right to attend a crèche as well as an école maternelle up to a maximum of 10 hours per working day.

In 2009, with the explicit objective of increasing the availability of childcare places, the government decided to create and support a new type of collective arrangement, called "jardins d'éveil", where 2 to 3 year-old children could be cared for. They are supposed to serve as bridges between the home and the nursery school. Vocal criticisms, however, were raised as the quality of this type of childcare would be patchier than in crèches where the statutory child-to-staff ratio is 8:1 compared to 12:1 in "jardins d'éveil" and the qualification requirements of the staff less stricter 12 .

These new centres were also widely viewed as an underhanded way to transfer more of the financial burden for care from the government to parents" shoulders by reducing the demand for places in nursery schools and siphoning it into the "jardins d'éveil". These centres have met, however, with very little success.

Conclusion

Though the "EU Framework of Law for Children"s Rights" 13 states that "all EU policies must be designed and implemented in line with the child"s best interests", new developments in France have given rise to increasing tensions and dilemmas despite In all these domains, responsibilities (spread over different social partners) are all too often dissipated which leads to a lack of accountability for actions taken; and no one is held responsible for instance for the mismatch between supply and demand of childcare at the local level. Spatial disparities in supply of places in centre-based settings also remain wide and continue to hinder access of all families to high quality childcare.

Last but not least, the issue of the predominantly female workforce in the childcare sector has not yet been addressed though it would be a significant component of a holistic and comprehensive approach to promoting high quality childcare.

  details, see[START_REF] Fagnani | France: Gender Equality, a Pipe Dream?[END_REF] Boyer, D. (2012) 1.1 Setting the scene for the institutions in charge of formal childcare provisions In relation to children under three responsibility for services is shared by several institutional actors: the national family allowance fund (Caisse Nationale des Allocations Familiales -CNAF), the national ministries in charge of social policies and health, local authorities and social partners, like the national union of family associations (Union Nationale des Associations Familiales --UNAF). Enterprises, non-profit/voluntary organisations, and the market still play a minor role in comparison to the state. Currently however, for-profit providers are increasingly being considered as real partners in policy development and service delivery in France. These services are, nevertheless, poorly coordinated. The most recent report of the national audit office (Cour des Comptes) released in July 2008 therefore recommended to "reinforce the coherence of their respective intervention" (Cour des comptes, 2008).The CNAF and its large network of decentralised CAFs (123 local family allowance funds) play a key and pivotal role in the funding and provision of childcare services.In theory social partners such as family organizations, employers" representatives and workers" trade-unions, which are represented on the Executive Board of the CNAF, periodically determine the orientations for intervention in family and childcare policies. In practice, decisions are made by the Government, whether approved or not by the Executive Board. It is solely at the local level that the Executive Boards of the CAFs have any real decision-making power, and in particular, a margin for manoeuvre in the funding and development of childcare services.Since 2002, "early childhood commissions" are working at the département level: they are in charge of bringing together all the relevant actors (local authorities, representatives of the ministry of education, the CAF, the trade unions and family associations) to enhance coherence, co-ordinate services, provide information to families (through for instance the internet site Monenfant.fr), increase equality of access to services and support innovation in the field.1.2. A complex combination of subsidized centre-based and home-based arrangements and a system based on the principle of universalityThe majority of children under three are, however, mainly cared for by one of the parents (mostly the mother, working or not) during the week.

1. 5

 5 Nursery schools: écoles maternelles Écoles maternelles are free for parents and are fully integrated into the school system under the national Ministry of Education, with the same guiding principles, opening hours, and administration as elementary schools. According to the French Education code "every child upon reaching the age of three has the right (but it is not compulsory) to attend a nursery school and almost all children aged three to six attend it full time or part-time. Children are usually grouped into three classes, according to age. Mixed-age grouping is relatively uncommon. Nursery schools are generally open from 8.30 am to 4.30 pm and have canteen facilities (under the supervision of a dietician) where fees are income-related. They are routinely closed on Wednesdays, but are supplemented by half-day Saturday sessions.

  Childminders are closely supervised by PMI services, though with a frequency depending on the local authorities. Before being licensed, they are interviewed by a social worker, a paediatric nurse, and a psychologist. The housing conditions and environment for receiving children should be approved, especially in terms of space, hygiene, and safety. As of March 2012 PMI services have been required to use common standards for criteria related to the registration of childminders. And since 2005 registration procedures have to take into account the childminder"s educational skills. The license is valid for five years and can be renewed for consecutive periods.It specifies the number (no more than 4 simultaneously) and the age of children that can be cared for by the childminder, either fulltime or part-time.Given that childminding is the most common childcare arrangement for children under three, in recent years policy-makers have been addressing in recent years the issue of their qualification. Indeed, though their average educational achievement had improved since the 1970s, in 2005, 49 % had no qualification whatsoever and 35 % had very low qualifications. Therefore, efforts to reduce the cost for parents of this type of care have been coupled with measures attempting to professionalise childminding. Since 2004 childminders have been required to receive 60 hours of additional training (in total 60 before and 60 in the two years following their registration). The training programme is paid and supervised by local authorities.

  All of them have to complete a year of specialization in children"s development, health and well-being. At the end of the training programme, a practical experience takes place: the student is required to work in a maternity ward, neonatal unit, paediatrics as well in a sector of PMI services.and in a crèche. The training programme is updated each year to take into account new health concerns. The second category of staff is the éducatrice de jeunes enfants (early childhood educator), who is required to have a high school diploma and to undergo over a period of 27 months of vocational training programme comprising both theoretical training and practical field experience. Auxiliaires de puéricultricethe third category of staffcan also attend this programme if they have three years of professional experience. If the centre has more than 40 places, there must be at least one éducatrice de jeunes enfants. They can develop educational projects and foster partnerships with families, schools, and other social and cultural settings. At least half of the staff in centres must be auxiliaires de puéricultrice (assistant pediatric nurse). The auxiliaire is required to attend an "école d'auxiliaires de puéricultrices' where they are provided with a vocational qualification programme over a period of 12 months (1 575 hours comprising theoretical and practical fieldwork). Training is open to candidates who have passed the entry exams and have either a professional certificate or have completed four years of secondary education. The training includes pedagogy and human development; education and care; child development and educational practice; group management; law; economics and social studies; and professional studies and methods. Training centres are mainly run privately, but accredited by the national Ministry of Health.In écoles maternelles, on the other hand, all teachers (professeur des écoles) are public servants and must have passed before teaching a national exam which is open to those who have a three-year college degree. The exam includes written papers in French, math, science and art, a practical exam in sport, and an oral exam on workplace experiences. Those who pass the exam enrol in one of the public academic institutes for a year of professional training (about 450 hours).

  attempts have been made to reconcile the quantitative with the qualitative in the formulation of consistent childcare policy. While the focus has continued to remain on supporting mothers" employment by subsidizing formal individual care arrangements as well as collective ones, reforms introduced since the mid-nineties illustrate clearly the ways in which employment policies have encroached on the ground previously occupied by French family policy.Moreover, reforms introduced by the government have created employment both on the supply-side (increased labour market participation of women) and on the demand-side (increased number of jobs in childcare services), but there are still important gaps in quality as far as childminders are concerned, and heterogeneity in this field is still the rule.

Table 1 :

 1 Main services and provisions (ECEC) available by child age

	Age of the	Maternity and	Parental leave	IAJE	Licensed	Nanny/day-	Nursery
	child	Paternity	(with or without	(crèches and	Childminders	care employee	schools
		leave*	a benefit)*	multi-accueil)			(écoles
							maternelles)
		Length of	Until the child	The child can	Main formal	Very few
		maternity	reaches three	attend up to a	childcare	parents can
		leave : 16	years.	maximum of 10	arrangement	afford to hire
		weeks	Under certain	hours per day	outside the	someone at
		Mothers having	conditions		parents	home
		a third or	parents can be	Licensing and
		higher order	provided with a	supervision by	Childcare	Parents are
	Under age 1	child: 24 weeks	flat-rate benefit	the local PMI	allowance paid	provided with a	-
		of leave	(€ 566 per	services (at the	by the CAF	childcare
			month in 2012)	department	Licensing and	allowance and
		Paternity	paid by the	level)	supervision by	tax breaks
		leave: 2 weeks	CAF		the local PMI
				Funded by	services (at the	The employee
				local	department	is not
				authorities and	level)	supervised by
				CAFs; Fees for		PMI sercvices
				parents are
				income-related
	Aged 1	-	Similar to	Similar to	Similar to	Similar to
			children less	children less	children less	children less	-
			than 1 year	than 1 year	than 1 year	than 1 year
		-	Similar to	Similar to	Similar to	Similar to	Toute petite
			children less	children less	children less	children less	section (very
			than 1 year	than 1 year	than 1 year	than 1 year	little section) or
							children may
					Children who	Children who	be integrated
					attend nursery	attend nursery	with the three-
	Aged 2				school only	school only	to-five year
					half time, can	half time, can	olds
					be looked after	be looked after
					by a	by a nanny the

Table 2 :

 2 Childcare arrangements for under-threes during the week (in %)

	All children	Both parents
	(in %)	work full-time
			(in %)
	Main	Second	Main
	childcare	childcare	childcare
	arrangement	arrangement	arrangement

Source:

Boyer et al (2012: 22-23)

. Data refers to 2007. Main childcare arrangement refers to the arrangement in which the child spends most of the

  in funding and remain a growth area in the French welfare state 4 .Therefore the system of public crèches, and more generally EAJE, has suffered no funding cutbacks. CNAF is the leading contributor (73 per cent) to childcare for under 3s. CNAF allocates funds to each decentralised CAF to help local authorities create and run child care centres. Both public crèches and the few for-profit ones receive funding from CAF on a per child basis if they use the national sliding fee scale based on family income. Because individual settings cannot charge top-up fees, there is little incentive for them to select well-off families as they receive the same amount of money per child by the local CAF. The aim of this flat funding is precisely to ensure social mix in collective centres. By contrast, on the whole, costs to the CNAF vary greatly according to the level of income of families accessing crèches, with low income families receiving higher subsidies(Boyer, 2012).

	arrangement. Many stakeholders are involved in funding: the state (through the
	ministry of education and tax breaks related to childcare allowances), the CAFs, the
	local authorities and the families. It is worth noticing that despite a general tightening
	of purse strings in public expenditures, childcare policies have continued to see

3 See "L'école maternelle'. Report of General Inspections, ministry of National Education, October 2011. increases

Table 3 -

 3 Children aged under 3: Breakdown according to the main childcare arrangement during the week and the family income level (in %)

							Nanny/
	Income per				Childcare	Ecole	day-	Other
	consumption	Parent	Relatives Licensed	centres	mater-	care		TOTAL
	unit	s		childminder	(EAJE)	nelle	employ
							ee
	First quintile	91	1	2	4	1	0	1	100
	Second	84	2	5	5	2	0	2	100
	quintile
	Third	64	6	18	9	2	0	1	100
	quintile
	Fourth	44	7	29	16	2	1	1	100
	quintile
	Fifth quintile	31	5	37	16	3	7	1	100
	Source: Borderies (2012).
	Annex

Located in the

neighbourhoods designated as "Sensitive Urban Areas" (Zones Urbaines Sensibles) or in communes with an "Urban social cohesion contracts" (contrats urbains de cohésion sociale, CUCS).

Referred to as assistantes maternelles (literally: maternal assistants).

As far as collective childcare facilities are concerned, CNAF expenditures increased by

59.4 per cent over the period 2006-2011. CNAF (2012), Prestations familiales 2011, Statistiques nationales, Paris.

To be eligible both parents have to be employed or registered as unemployed or attending a training course.

Beyond this statutory wage, parents are free to pay more but the related social contributions will not be reimbursed by the CAF.

There are also strong geographical disparities: childminders living in the metropolitan Paris areain particular those located in Paris downtown -are those who are the best paid (1440 € per month on average) as a result of the mismatch between supply and demand[START_REF] Fagnani | Des assistantes maternelles mieux formées et plus qualifiées. Les parents consentiraient-ils à augmenter la rémunération ?" (Better trained and more qualified childminders[END_REF].

The gap between supply and demand for formal childcare has been estimated at a minimum of 350,000 places by the Haut Conseil de la Famille, the High Family Council which advises the National government on family affairs. http://www.hcf-famille.fr/IMG/pdf/Lettre_HCF_no2-3.pdf

In cases where it is difficult for parents to make alternative arrangements or when the caregiver is held in high esteem by the family.

In April 2010 they drew up a petition against the new legislation under the banner of "Pas de bébé à la consigne" (Left luggage: no babies allowed) and organised several demonstrations. http:www.pasdebebesalaconsigne.com

[START_REF] Strazdins | Unsociable work? Non-standard work schedules, family relationships and children"s well-being[END_REF] have demonstrated that non-standard work schedules have detrimental effects on children"s well-being and on the quality of interactions within the family.


Loïc Deyra
email: loic.deyra@institutoptique.fr

Simon Ilas

Xavier Délen

Pascal Loiseau

François Balembois

Gerard Aka

François Salin

Patrick Georges

Third harmonic generation at 343nm in nonlinear Ca 5 (BO 3 ) 3 F (CBF) crystals

We demonstrate for the first time UV generation at 343 nm by frequency-tripling in the new non-hygroscopic Ca5(BO3)3F crystal. A boule of CBF crystal was grown and cut along the two possible phase matching configurations for third harmonic generation in plans XY and YZ. 300 mW of UV average power have been obtained with a deff estimated at 0.45 pm/V for the XY plan and 0.38 pm/V for the YZ plan.

Introduction

Ultraviolet lasers are extensively used in the industry for material processing. Solid-state lasers have replaced gas lasers as reliable UV sources, thanks to the progress in the nonlinear crystals used for frequency conversions from infrared to ultraviolet. The most used nonlinear crystal for third harmonic generation (THG) is LiB3O5 (LBO), which has demonstrated conversion efficiencies from infrared to UV up to 40% [START_REF] Gapontsev | Third harmonic frequency generation by Type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal[END_REF]. While its optical properties and crystal qualities are excellent, it still suffers from hygroscopic issues that hinder its long-term operation potential [START_REF] Hong | Improvement and formation of UV-induced damage on LBO crystal surface during long-term high-power third-harmonic generation[END_REF]. For this reason, other crystals from the borate family have shown growing interest thanks to their non-hygroscopic nature. In 2012, a power of 3 mW of 355 nm laser radiation was demonstrated using the non-hygroscopic Na3La9O3(BO3)8 (NLBO) crystal, but the crystal was damaged in the process [START_REF] La | 355nm laser generation based on NLBO crystal[END_REF].In 2009, 0.6 mW were demonstrated in a BaAlBO3F2 (BABF) crystal [START_REF] Zhou | High-efficiency 355 nm generation in barium aluminum borate diflouride (BaAlBO 3 F 2)[END_REF]. La2CaB10O19 (LCB) crystals only operate in type-I third harmonic generation and have less interesting optical properties than LBO, but they can be grown in large dimensions and have recently shown high conversion efficiencies in the UV [START_REF] Wang | 31.6-W, 355-nm generation with La2CaB10O19 crystals[END_REF]. YAl3(BO3)4 crystals have shown very interesting properties for UV generation [START_REF] Liu | High-power 266 nm ultraviolet generation in yttrium aluminum borate[END_REF], but the growth of large and transparent UV crystals is still a subject under investigation [START_REF] Liu | Growth and optical properties of UV transparent YAB crystals[END_REF].

One other promising crystal that has been developed is the member of the fluoborate family Ca5(BO3)3F (CBF), which is chemically stable (non-hygroscopic). While its frequency doubling properties have already been determined [START_REF] Xu | Nonlinear optical properties of Ca5(BO3)3F crystal[END_REF], no previous experimental studies had been made about its third harmonic properties.

Crystal characterization

CBF is a biaxial nonlinear crystal belonging to the fluoborate family. It crystallizes in the acentic space group Cm (Z=2) [START_REF] Xu | Nonlinear optical properties of Ca5(BO3)3F crystal[END_REF], and be grown by flux method, using LiF as a flux. The nonlinear properties of CBF were calculated in previous work based on the refractive index measurement [START_REF] Xu | Nonlinear optical properties of Ca5(BO3)3F crystal[END_REF], and are displayed in Table 1 compared to classical third harmonic crystals such as LBO and BBO. We chose to display only type-II third harmonic generators because this configuration is easier to implement thanks to the appropriate state of polarization at the end of the SHG crystal. We can see that CBF has nonlinear properties comparable to LBO in terms of walk-off and acceptance angle. In the previous study on CBF, the nonlinear susceptibility deff was measured only for second harmonic generation from 1064 nm to 532 nm. The deff values for third harmonic generation inset in Table 1 are determined below in this study.

Table 1: nonlinear properties of CBF compared to commercial type-II THG crystals (* deduced from this study)

A CBF crystal with a large size (diameter = 17 mm and length = 35 mm) has been obtained by using 20wt% LiF as flux in air. The CBF boule was cut in two different planes corresponding to the two possible type-II THG phase matching directions. Two crystals of dimensions 3x3x3 mm 3 were cut in the YZ plane, with θ=57.7° and φ=90°. Then, a third crystal of dimension 3x3x5 mm 3 was cut in the XY plane with θ=90° and φ=72.6°. The 3 crystals picture is displayed in Figure 1. The theoretical nonlinearities can be calculated from the following formulas:

The crystals transmittance was measured at room temperature from 200 nm to 800 nm. The transmission curves are displayed in Figure 2. The XY-cut and YZ-cut CBF crystals show a transmission at 800 nm of respectively 85 % and 86 % (With a transmittance at 343 nm of respectively 73 % and 81 %). These values are to be compared to the theoretical absorption calculated with the refractive indexes, displayed in dotted line in Figure 2. The differences between theoretical and measured transmittance are attributed to residual impurities of LiF during the crystal growth. The differences between the two cut plans are only due to the XY crystal being longer (5mm) than the YZ crystal (3mm).

Third harmonic generation

The experimental setup is detailed in Figure 3. We used for the experiment a previously developed infrared source emitting 20 W at 1030 nm at a repetition rate of 30 kHz with pulse width of 15 ns, TEM00 beam profile and Fourier-limited spectral linewidth [START_REF] Délen | Hybrid master oscillator power amplifier nanosecond laser source at 257 nm[END_REF]. A standard third harmonic generation set-up was implemented: a 20 mm long, type-I LBO was used in NCPM configuration to obtain 12 W of green power. The frequency tripling crystal was placed right after the second harmonic crystal, and the focal point was set at the entrance of the THG crystal with a beam diameter of 170 µm at 1030 nm.

Both XY-cut and YZ-cut type II-CBF crystals were tested and the UV output power was measured, the results being displayed in Figure 3. The wavelength was verified to be at 343 nm with a UV-sensitive spectrometer.

Figure 4 : Ouput power at 343nm for both CBF cut plans versus the input IR 1030 nm power When the 3x3x3 mm 3 CBF cut in the YZ plan was used, up to 125 mW of UV power was obtained for a pump power at 1030 nm of 20W. Both YZ-cut crystals yield the same results. When the 3x3x5 mm 3 CBF cut in the XY plan was used, up to 400 mW of UV power was obtained.

Then, in order to evaluate the deff values, we replaced the CBF crystals with a standard 15 mm long type-II LBO in critical phase-matching configuration. Up to 5.6 W of average power at 343 nm was obtained at maximum IR power. We then used the calculation software SNLO [START_REF] Smith | Computer code SNLO(available from the authors at no charge)[END_REF] to fit the reference experiment with the type-II LBO, then adapted the simulation with the optical properties of CBF [START_REF] Xu | Nonlinear optical properties of Ca5(BO3)3F crystal[END_REF] and a variable parameter for the deff values. The deduced values of deff for the XY and YZ plans of CBF were respectively 0.45 and 0.38 pm/V, indicating that the third harmonic generation process in the XY plan has a higher nonlinear coefficient. These value slightly differ from the theoretical nonlinearities calculated above, which can be easily explained because of the many possible sources of imprecisions such as the absorption measurements, the beam size inside the crystal, or the pulse duration. By comparison, the deff value of type-II LBO for THG of 1030 nm is deff= 0.46pm/V. We find it important to note that while the difference between the UV powers obtained with CBF and LBO can seem important, it is only related to the length of the used crystals: theoretically, a CBF crystal of 20 mm long (as the tested LBO) with the optical properties measured in this study would produce comparable UV output power.

The measured beam profile for the conversion in the XY-cut CBF in the UV showed no sign of degradation that could indicate structure defects. The stability of the UV power was also measured (Figure 5). After twenty minutes, the UV power stabilized around 300 mW and was stable for more than half an hour. We attribute the slow decay before stabilisation of the UV power to residual impurities in the crystal. Same phenomena, but of much higher intensities, can be observed for example in KTP crystals during second harmonic generation in the visible range [START_REF] Liao | Thermally induced dephasing in periodically poled KTiOPO4 nonlinear crystals[END_REF].

Conclusion

In conclusion, these results show that a UV laser can be realized by third harmonic generation in the non-hygroscopic borate crystal Ca5(BO3)3F (CBF). We demonstrate 300mW of stable 343nm output, which is the first demonstration of UV generation in this non-hygroscopic crystal. We measured a nonlinear coefficient (deff) similar to the one of Type-II LBO. New flux and growth methods are currently under development. Hence, with larger crystals grown as expected in the near future, CBF could be considered as an alternative to LBO.

Aknowledgements

Authors would like to acknowledge the DGA and EADS foundation for PhD funding. This work is supported by the french ANR agency (ANR UV-Challenge, N° ANR: 12-B504-0014-01)

  31 𝑠𝑖𝑛 2 𝜑 + 𝑑 32 𝑐𝑜𝑠²𝜑 (1) 𝑑 𝑒𝑓𝑓 𝐼𝐼 𝑌𝑍 = 𝑑 31 𝑠𝑖𝑛𝜃 (2) By using d31=0.49 pm/V and d32=-0.53 pm/V [9], the theoretical nonlinearities of CBF for THG of 1030nm are d XY eff II=0.41 pm/V and d YZ eff II=0.45 pm/V.

Figure 1 :

 1 Figure 1: CBF boule (left) and cut crystals (right), cut in YZ plan (a&b) and XY plan (c)

Figure 2 :

 2 Figure 2: Measured transmission for both XY and YZ-cut crystals

Figure 3 :

 3 Figure 3: Experimental set-up

Figure 5 :

 5 Figure 5: UV power stability over one hour and beam profile of the 343nm output


Inter-comparison exercises on dissolved gases for groundwater dating -(1) Goals of the exercise and site choice, validation of the sampling strategy

Keywords: inter-comparison exercise, groundwater dating, environmental tracers

Two international inter-comparison exercises devoted to dissolved gases and isotope analyses in groundwater, used as tools for groundwater dating were organized in 2012 in France (IDES-Université Paris Sud -CNRS and OSUR -Université Rennes 1-CNRS). The goal was to compare sampling and analytical protocols through results obtained by the community of groundwater dating laboratories. The two exercises were: GDAT1 on three supply boreholes in a homogeneous sand-aquifer of Fontainebleau (Paris Basin, France) and GDAT2 on two supply boreholes (shallow and deep) in a fractured rock aquifer in French Brittany. This twostep exercise is the first exercise which included a large number of gases and isotopes usually used in groundwater as dating tools and also permit to discuss the uncertainties related to sampling protocols issuing from each laboratory methods. The two tests allowed 31 Laboratories from 14 countries to compare their protocols for both sampling and analyses. This paper presents the participants and parameters measured, and focuses on the validation of the sampling strategy. Two laboratories analyzed CFC and SF 6 samples collected at regular intervals during the sampling operations in order to verify water homogeneity. The results obtained by the two "reference" laboratories along with monitoring of field parameters showed no clear trend of gas concentration or physic-chemical properties. It can be concluded that the pumped groundwater composition remained constant during sampling.

This study also shows the potential for relatively constant pumped groundwater composition from a specific well despite the complexity and/or mixing processes that may occur at a larger scale in the aquifer.

Introduction

Groundwater dating through dissolved gases (CFCs/SF 6 ) and isotopic analyses ( 14 C, 3 H, 3 He, 20 Ne, 40 Ar, 84 Kr) has been used for decades, (Busenberg andPlummer, 1992, 2000;[START_REF] Clark | Environmental Isotopes in Hydrology[END_REF][START_REF] Solomon | A Validation of the 3 H/ 3 He Method for Determining Groundwater Recharge[END_REF]. More recently 39 Ar, 81 Kr, 85 Kr methods [START_REF] Loosli | Noble gas radioisotopes: 37 Ar, 85 Kr, 39 Ar, 81 Kr[END_REF], SF 5 CF 3 and CF-13 [START_REF] Busenberg | Dating groundwater with trifluoromethyl sulfurpentafluoride (SF5CF3), sulfur hexafluoride (SF6), CF3Cl (CFC-13) and CF2Cl2 (CFC-12)[END_REF]) appeared to have great potential.

Environmental tracers such as dissolved gases and various isotopes of some gases are mostly present in very low concentrations in groundwater, due to their low concentration in the atmosphere and their low solubility in water. CFCs and SF 6 , among the most used dissolved gases, have ground water concentrations of about 10 -12 to 10 -16 mol/kg, respectively. Noble gas isotopes such as 3 He, 4 He, 20 Ne, 22 Ne, 36 Ar, 40 Ar, 84 Kr and 132 Xe have ground water concentrations between 10 -4 to 10 -15 CCstp/g. These concentrations require very precise sampling protocols, storage conditions and very sensitive analytical methods. Degassing and air contamination must be avoided at each step of sampling and analysis. Detailed sampling protocols have been published. (IAEA, 2006;Busenberg andPlummer, 1992, 2000).

However, each laboratory uses its own specific and adapted sampling and analytical protocol for historical reasons, or due to specific improvements. For example, in the case of CFC sampling, glass bottles with various caps and volumes, as well as steel flasks or field gas extraction can be used. Both headspace and purge-and-trap extraction are used for SF 6 analysis each requiring different sampling procedures. These differences in protocols may introduce a high degree of variability among different laboratories' measurements.

More than 40 laboratories worldwide use these environmental tracers for hydrogeological characterization. Guidebooks devoted to these methods have been published by the International Atomic Energy Agency (IAEA, 2006(IAEA, , 2011) ) and this topic has been the subject of special journal issues [START_REF] Osenbrück | Selected papers from the international workshop G-DAT 2008: groundwater dating using environmental tracers[END_REF]. Analytic intercomparison has been carried out for 3 H, 14 C and stable isotopes (IAEA organization). However an inter-comparison exercise devoted to groundwater dating has never been carried out. The aim of the 2012 GDAT inter-comparison exercise was to compare how the various sampling and analytical protocols used by different laboratories could affect (or not) the concentration determination of environmental tracers and groundwater dating.

A source of standardized water to sample for each laboratory participating in the intercomparison was established. Laboratory methods such as an equilibrated water tank were difficult to run at the scale of 30 laboratories requiring hundreds of samples. It was decided to run the exercise under field conditions by sampling ground water at a variety of boreholes. Sampling of groundwater from boreholes for drinking-water supply offers several advantages. It ensures a good renewal of water, stabilized water level in the borehole and stable chemistry and temperature. Knowledge of dissolved gas concentrations in chosen boreholes had to be established before the exercise through previous studies, in order to better design the exercise and focus on specific concentration ranges of the target analytes. The desired target ground waters were (1) modern waters (age less than 15 yrs) where 3 H and CFC groundwater dating methods have a poor precision but SF 6 has high resolution, and (2) «blank" samples (age greater than 60 yrs) to test for sampling contamination. A key concern in the design of such an intercomparison was to make sure that all participants sampled a similar groundwater. Although it appears as a trivial condition, constant field conditions and steady state chemistry for several hours of pumping can not be assumed. Besides being the necessary condition for the GDAT exercise, this point represents a fundamental question in chemical hydrogeology. Aquifers present a degree of heterogeneity which makes it difficult to interpret a unique sample as a part of complex mixing processes at various scales. The GDAT exercises thus raised a preliminary question of how to obtain a unique but steady state sample for 30 laboratories representing the same water chemistry.

The results of the intercomparison exercises are described in two companion papers, one devoted to CFCs and SF 6 (Labasque et al. this issue), the second one to noble gases and 3 H (Visser et al., this issue). This paper presents the points that were discussed in order to define the strategy of the intercomparison exercises, the rules used to determine the sampling sites and the sampling strategy. We also present the geological and hydrogeological context of the sampling sites, the team who participated and the methods used.

Materials and methods

Description of the sampling sites

The inter-comparison exercise proposed in parallel to the GDAT-2012 meeting included two sampling phases in homogeneous and heterogeneous fractured rock aquifers (GDAT1 and GDAT2) which are described below Homogeneous aquifer : The first GDAT1 exercise was carried out in January 2012 close to the Fontainebleau forest (about 40 km south of Paris) in sandy homogeneous aquifers in the Paris basin. The Fontainebleau site is devoted to drinking water abstraction and includes two aquifers, the Albian sand aquifer and the Fontainebleau Oligocene sand aquifer.

This basin is a multi-layered aquifer-aquitard system associated with a southeast to northwest topographically-driven flow with recharge zones at the highest outcrops and discharge zones along the main rivers (Seine, Somme) or in the Manche Channel. Some of these aquifers are exploited, e.g. the Albian sand formation, a deep protected aquifer, is used for water supply.

The Albian sands of the Paris Basin represent one of the shallowest (600 mbgl below ground level) confined aquifers in this thick sedimentary basin. Hydrogeological informations lead us to identify and select a flow line between the recharge area (Gien-Auxerre, SE) and the middle of the Basin (Paris). This flow line is characterized by a large cone of depression beneath Paris induced by the massive pumping performed since last century. A recent hydrological and geochemical study (Raoult et al., 1997) demonstrates that locally the Albian groundwater is variously mixed with water rising up from the underlying Neocomian aquifer.

One of the three boreholes chosen during the Gdat1 exercise is screened at 556 to 592 mbgl in the Albian aquifer. This borehole was under continuous pumping until a month before GADT1 sampling.

The Fontainebleau Oligocene sand-aquifer was chosen because it is hydrogeologically well known from previous tracer investigations [START_REF] Schneider | Accroissement récent des teneurs en sulfates dans la nappe des sables de Fontainebleau : origines et implications pour la gestion de cette ressource[END_REF][START_REF] Alvarado | Constraining the age distribution of highly mixed groundwater using 39Ar: A multiple environmental tracer ( 3 H/ 3 He, 85 Kr, 39 Ar, and 14 C) study in the semiconfined Fontainebleau Sands Aquifer (France)[END_REF][START_REF] Alvarado | European climate variations over the past half-millennium reconstructed from groundwater[END_REF]. It is located in the shallower part of the Paris Basin and constituted of very fine well-sorted silica grains. The Fontainebleau sand-formation has a thickness of 50-70 m, a hydraulic transmissivity of 1 x 10 -3 to 5 x 10 -3 m 2 .s -1 and a mean total porosity of about 25% [START_REF] Mégnien | Hydrogéologie du centre du bassin de Paris[END_REF][START_REF] Mercier | Inventaire des ressources aquifères et vulnérabilité du département des Yvelines[END_REF][START_REF] Ménillet | Meulières, argiles à meulières et meuliérisation: historique, évolution des termes et hypothèses génétiques [Meulières, Clay meulières and meuliérisation: historical evolution of the terms and assumptions genetic[END_REF]. The hydrogeological situation is characterized by spatially extended recharge rates ranging from 100 to 150 mm/yr [START_REF] Alvarado | Constraining the age distribution of highly mixed groundwater using 39Ar: A multiple environmental tracer ( 3 H/ 3 He, 85 Kr, 39 Ar, and 14 C) study in the semiconfined Fontainebleau Sands Aquifer (France)[END_REF]. Wells in the Fontainebleau sand-aquifer have generally long screened intervals. The boreholes SLP4 and SLP5 were selected for the study for two main reasons : i) because the use of these wells for water supply is continuous and the drawdown was stabilized weeks before sampling, and ii) because the age structure of groundwater is relatively well constrained. [START_REF] Alvarado | Constraining the age distribution of highly mixed groundwater using 39Ar: A multiple environmental tracer ( 3 H/ 3 He, 85 Kr, 39 Ar, and 14 C) study in the semiconfined Fontainebleau Sands Aquifer (France)[END_REF] concluded that flow paths intercepted by the well have residence-times that range from modern to a few hundreds years, with a mean exponential residence-time of about 100 years.

The SLP4 and SLP5 wells have a long screened interval between 40 to 54 mbgl (meter below ground level) and 45 to 68 mbgl respectively, entirely within the sand formation, with an inner diameter of 0.6 m of CUAU inox filter.

Sampling operations were carried out on 1 st and 2 nd of February 2012 at an unusual outdoor temperature about -4°C. Teams present on site met the day before in order to organize the sampling operations. The three water supply boreholes were sampled successively, directly at the pump tap which provided stabilized water. Except for the borehole in the Albian formation, where the team had to leave before the end of sampling due to an unexpected decision of the site management, sampling took place without technical problems.

Heterogeneous aquifer : The second inter-comparison exercise, GDAT2 was carried out on 18 and 19 of October 2012 in a fractured rock aquifer North of Rennes (France). This water plant is located in Brioverian schists made of alternating centimeter-thick layers of sandstones, silts and clay-rich layers [START_REF] Trautmann | Carte géologique de la France au 1/50000[END_REF]. Alteration of this crystalline rock leads to the formation of an unconsolidated saprolite observed during drilling along the first 10 to 15 m. The site includes two supply wells : a shallow one 15 m depth, named "Captage", and a deep one 105 m-depth, named "forage". Pumping for water supply is around 10 m 3 /h. Previous studies [START_REF] Ayraud | Physical, biogeochemical and isotopic processes related to heterogeneity of a shallow crystalline rock aquifer[END_REF] indicated that the shallow well provides "young" water from the shallow weathered compartment with residence time ranging from 15 to 25 yrs. The deep well, in the fractured fresh rock, provides "old" waters from fault zones below 40 m depth.

Groundwater at this depth presents higher salinity (mean Cl -= 100 mg/L) indicating a complex origin and mixing between the shallow compartment and deep groundwater. This well has been monitored since the beginning of pumping in 2003. Although a drift of the composition has been observed during this period, the evolution is very slow and offers some guaranty of stability for a short pumping exercise. Although (usual) slightly rainy weather made conditions more difficult, sampling took place without any technical problems and all sampling planned was realized, as well as the test of a passive-sampler chain in a monitoring piezometer.

Sampling conditions

For the two sites, each borehole was equipped with nylon tubing lines. Each line was kept to minimum practical length. One line was dedicated to CFCs and SF 6 sampling, the second one to noble gases and tritium, and the last one to specific sampling (field extraction or large volume sampling). The flow of each line was around 300 l/h. After one hour of flushing, the field parameters were stabilized and sampling started with an order decided by the organizers and all the participants. A critical point was the organization of the sampling steps due to the numerous persons waiting for sampling in a very small and confined place. Each Lab's sampling containers were labeled and the order and the time of sampling of each Lab's containers were thus written down along with field parameters during each sampling step.

Insurance of sample water homogeneity

As mentioned in the introduction, insurance of the homogeneity of all samples collected during the experiment was a necessary condition. In order to measure water homogeneity, three different parameters were monitored during sampling : (1) groundwater samples for CFC and SF 6 analyses were collected at the beginning, in the middle and at the end of sampling operations. These samples were analyzed by two different laboratories (Géosciences Rennes (GR) and USGS Reston laboratory). (2) Major anions and dissolved gases (N 2 and Ar) were also sampled and analyzed in the same way in the Geosciences Rennes Laboratory.

3) Field parameters (T°, Cond, pH, Eh, and dissolved oxygen, WTW sensors) were monitored during the entire sampling operation in order to detect any obvious change in the water chemical composition.

CFC and SF 6 were sampled in steel ampouls (40ml and 300ml respectively) by GR and analysed by Purge and trap and GC/ECD. USGS samples were collected in glass bottles (150 ml for CFC and 1L for SF 6 ). Analytical systems used at the USGS lab are described in Busenberg andPlummer (1992, 2000). Uncertainty was fixed at 3% for values above 0.1 pmol/kg for CFC and 0.1 fmol/kg for SF 6 . For lower values, uncertainty was fixed at 20%.

Those values are generally used by most authors (Busenberg andPlummer, 1992, 2000;Volmer and Weiss, 2002). For anions analyses, ion chromatography (DIONEX DX120) was used with an uncertainty of about 5%. For Ar and N 2 gas, chromatography was used with a thermal conductivity detector (µGC/TCD) after headspace extraction following the Sugisaki et al. method [START_REF] Sugisaki | Simplified analyses of He, Ne, and Ar dissolved in natural waters[END_REF] with analytical precision of 5%. The variations are expressed as the difference between the value at the end and the value at the beginning of the pumping step, divided by the analytical uncertainty (tables 2 and 3).

Results of the field GDAT1 and GDAT2 exercises

The list of participants is presented in table 1. Thirty one laboratories from 14 countries participated in the intercomparison exercises. Parameters measured by each team and their contributions to each exercise are indicated. Details on the sampling system are also specified.

The participation in an exercise dedicated to CFC and SF 6 gas standard analysis is also indicated. Results of the exercises are discussed in specific companion publications.

Data analysis focused on (1) field parameters, anions, N 2 , Ar (Table 2), ( 2) CFCs and SF 6 measurements (Table 3) realized on SLP4 (GDAT1), Captage and Forage boreholes (GDAT2) at the beginning and end of sampling and on 3) continuous field parameters acquisition. For SLP5 and Albian wells, the time was too short to sample gases and anions at the end of sampling operations. However, no modification of the field parameters occurred during sampling of these boreholes.

CFC and SF 6 concentration evolutions during sampling operations are illustrated in fig 1, 2 and 3 for SLP4, Captage and Forage boreholes respectively. For the GR and USGS laboratories, A and E labels are used. SLP4 sampling was realized by all the participants within 4 hours. Conductivity, pH, Redox and major anion concentrations remained unchanged during the sampling period (Table2). A temperature rise was noticed (+3.3 °C). A slight decrease (Table 3) in the CFC-113 value (-2 and -1 for GR and USGS, respectively) and a decrease in the USGS values for CFC-11 and CFC-12 (-5) can be seen. The depletions of CFC-11 and CFC-12 were not measured by GR.

The CFC-12 measured by USGS at t+4h, is in agreement with values obtained by GR. So a bad sampling at the beginning of the pumping could explain the possible contamination of the USGS sample. For CFC-11, the initial value (t0) measured by USGS is in agreement with GR values, no reasons was found to explain the decrease measured by USGS, except a slight degradation of this compounds before the analyze for USGS samples. CFC-113 concentrations measured are low (0.04 to 0.07 pmol/kg) and close to quantification limits, around 0.024 pmol/kg (Volmer and Weiss, 2002). The modifications of the CFC-113 concentrations during sampling and observed by the two laboratories could be due to rinsing of the tubes. Nylon tubing is not ideal for CFC sampling closed to detection limit, copper tubing should be preferred [START_REF] Busenberg | Use of chlorofluorocarbons (CCl3F and CCl2F2) as hydrologic tracers and age-dating tools: Example -The alluvium and terrace system of central Oklahoma[END_REF]. SF 6 measurements show almost unchanged concentrations for GR and USGS (-2 and 0 respectively). As a whole, it can be concluded that no major modification of the gas water composition was noticed during sampling of SLP4. Very low CFCs and SF 6 concentrations were not affected by the 4 hrs long sampling period. Sampling by all the participants of the "Forage" borehole was completed within 6 hours. An increase in redox potential was measured (+5), correlated to a decrease in nitrogen concentrations (-12). Other field parameters and Ar concentrations remained unchanged during sampling. An increase in CFC-11 concentration was measured by GR (+2) and USGS (+4). An increase in CFC-12 concentration was measured as well by GR (+4) but not by USGS (-1). GR measured a slight increase in CFC-113 (+2) while a slight modification of CFC-113 concentration was measured during the last 3 hours of pumping (0.011 to 0.025 pmol/kg) by USGS. As for the SLP4 borehole, CFC-113 concentrations were close to the detection limits (0.01 pmol/kg and 0.024 pmol/kg) and these evolutions are probably not significant. This is confirmed by the constant SF 6 concentrations measured by the two laboratories (+1 for GR and -1 for USGS).

Discussion and conclusion

These GDAT exercises consisted of the sampling of various boreholes in two sand-aquifers and the two compartments of a heterogeneous fractured rock aquifer. Previous studies have

shown that these wells belong to a complex hydrogeological structure where large mixing processes occur. The Albian well intercepts a 100 km scale flow line [START_REF] Alvarado | Constraining the age distribution of highly mixed groundwater using 39Ar: A multiple environmental tracer ( 3 H/ 3 He, 85 Kr, 39 Ar, and 14 C) study in the semiconfined Fontainebleau Sands Aquifer (France)[END_REF] whilst the two wells of the fractured rock site belong to a large mixing process between surface waters from the shallow weathered compartment, and deep and moderately saline waters [START_REF] Ayraud | Compartmentalization of physical and chemical properties in hard-rock aquifers deduced from chemical and groundwater age analyses[END_REF]. The task of sampling groundwater with a relatively constant composition through time is thus not trivial. Furthermore, the intercomparison exercise required a very high level of homogeneity for chemical concentrations at the picomole or femtomole scale. The sampling procedure of the GDAT sampling operations thus included the collection of replicate reference samples during the sampling. These samples were analyzed by two laboratories in order to provide validity to the experiment.

All the measurements out of the reference samples collected during the GDATexercises showed no clear and significant modification of the composition of the water pumped during the sampling periods. Even if some samples of CFC and SF 6 can showed slight differences between the two laboratories, and a slight decrease or increase during pumping, no clear trend was noticed at the picomole level for CFC and fentomole level for SF 6 by the two reference labs. This point confirms that the necessary condition of a homogeneous groundwater body sampled by all the GDAT participants has been fulfilled. It also shows that the great complexity of an aquifer does not prevent it from producing a relatively constant groundwater flow from a specific well. Comparison of the results of this study with previous studies shows that this is true at the scale of several years and the result of this study shows that this is also true at a very high degree of precision for at least several hours of sampling.

Although this point was discussed and remained a challenge at the beginning of the GDAT experiment design, this study shows that it is possible to get a homogeneous sample for many participants to share from field boreholes. It should be noted that the choice of supply boreholes it undoubtedly an important condition for success. These wells have relatively high permeability and steady state hydrogeological conditions which make the constancy of water composition more likely. The pumping equipment and all associated piping and tubing are permanently installed and most likely in equilibrium with the pumped water mixture.

Furthermore sampling directly at the well tap provided similar pumping conditions for all participants during the sampling period.

This long-term sampling with various methods also provided several lessons regarding sampling. Most of the discrepancy of the results between laboratories could be due to bad sampling with for example bubble entrapment or air contact. Sample tubing has to be rinsed for hours before final sample collection. Copper tubes should be preferred for low concentrations CFC, in order to prevent contamination. Finally, an order of sampling has to be followed and "reference" samples have to be inserted regularly in order to verify the stability of the water composition. Storage time should also be taken into account for results interpretation, due to risk of contamination or degradation of dissolved gases. Unc.

-----------+/-10 +/-0.1 +/-0.5 +/-10 +/-0.5 +/-0.5 +/-0.5 +/-5% +/-5%

  Groundwater sampling in the Captage borehole was completed within 6 hours. A large change in the redox potential (+7) and a slight decrease in major anion concentrations were noticed (Cl -:-5; NO 3 -:-10; SO 4 2-:-1). Conductivity, pH, temperature, N 2 and Ar concentrations remained unchanged during sampling. GR measured a decrease in CFC-113 (-10), not correlated with the other CFC or to USGS CFC-113 measurements. An increase of SF 6 concentrations (+7) was measured by USGS but not by GR (-2). CFC-11 concentrations remained unchanged for the two laboratories. A decrease of CFC-12 concentrations was noticed by GR (-3) but not by USGS. Even if CFC and SF 6 concentrations are high onCaptage well, as compared to SLP4, differences between the beginning and the end of pumping are in the same range, without a clear trend.

Geosciences

  Rennes and USGS Reston laboratory during sampling operations. Evolution of parameters is normalized to analytical uncertainty. *: evolution through three last hours.

Figure 1 :

 1 Figure 1 : Evolution of CFCs and SF6 concentrations in groundwater from SLP4 well, at the beginning (t0) and the end (t+4h) of pumping. Data obtained by GR (A) and USGS (E) laboratories.

Figure 2 :

 2 Figure 2: Evolution of CFCs and SF 6 concentrations in groundwater from "Captage" well during sampling. Data obtained by GR (A) and USGS (E) laboratories.

Figure 3 :Highlights••

 3 Figure 3 : Evolution of CFCs and SF6 concentrations in groundwater from "Forage" well during pumping. Data obtained by GR (A) and USGS (E).

Table 2 :

 2 Filed physic-chemical parameters measured on field, anions, nitrogen and argon results measured in the Rennes Laboratory.Evolution of parameters is normalized to analytical uncertainty.

	Borehol	Samplin	CFC1	CFC11	CFC1	CFC12	CFC11	CFC113	SF 6 GR(A	SF 6 USGS(E
	e	g time	1	USGS(E	2	USGS(E	3	USGS(E	)	)
			GR(A	)	GR(A	)	GR(A)	)
			)		)
	SLP4	t0	0.988	0.971		0.549	0.068	0.074	1.8*10 -4	2.49+10 -4
			5		6
	SLP4	t1	0.977	0.806	0.489	0.474	0.041	0.057	1.7*10-4 2.48*10 -4
		(+6hrs)	6		3
	Unc		0.03	0.03	0.015	0.016	0.013	0.013	5*10 -6	7*10 -6
	(t1-		0	-5	+1	-5	-2	-1	-2	0
	t0)/unc
	Captage t0	3.869	3.782	2.417	2.491	0.366	0.337	2.26*10 -3 2.45*10 -3
	Captage t (+3hrs) 3.868	3.916	2.184	2.595	0.341	0.338
	Captage t1	3.901	3.923	2.232	2.491	0.265	0.334	2.15*10 -3 2.96*10 -3
		(+6hrs)
	Unc		0.1	0.1	0.07	0.07	0.01	0.01	7*10 -5	7*10 -5
	(t1-		0	+1	-3	0	-10	0	-2	+7
	t0)/unc
	Forage	t0	0.034	0.014	0.963	1.102	0.032		1.37*10 -3 1.36*10 -3
	Forage	t (+3hrs) 0.030	0.048	0.951	1.063	0.039	0.011	1.32*10 -3

Table 3 :

 3 dissolved gases concentrations (pmol/kg) measured at regular intervals by

Acknowledgments : Authors would like to thank the council of Betton town and the water structure SMPBR, VEOLIA EAU and Source du Val Saint Lambert Company, for site acess and facilities for groundwater sampling. The GDAT intercomparison exercise benefitted from the help and/or funding of the International Atomic Energy association, IDES laboratory (UMR 8148), Université Rennes1, CNRS, OSUR (Rennes Universe Sciences Observatory), Géosciences Rennes laboratory, French Ministry for Education and Research, Région Bretagne and VEOLIA Eau. Financial and scientific support was also provided by the H+ network (Hydrogeology site network, INSU-CNRS).