ILIAS-JRA2 Production of enriched Selenium -2 kilos « ITEP-Kurchatov » -New contacts with ECP-Krasnoyarsk -New production from Tomsk -What’s next ? Integrated Large Infrastructures for Astroparticle Science

Second kilogram of enriched Selenium “ITEP-Kurchatov” (A. Barabash, L. Sosnin and A. Cheltsov) 22 days of statistics Sample (mBq/kg) Mass e (kg) Time(h) 40 K 60 Co 137 Cs 238 U 235 U 226 Ra 228 Th 228 Ra 106 Ru 82 Se powder 1300< ± ± ± ± 5< ± 71.6 ± 524 ± 3 First kilogram, reminder: Sample (mBq/k) Masse (kg) Time(h) 40 K 60 Co 137 Cs 238 U 235 U 226 Ra 228 Th 228 Ra 106 Ru 82 Se powder ± ± 0.3< ± ± ± ± ± ± 3

Collaboration meeting NEMO/SuperNEMO, Prague, November 2004

November 2004

To keep in mind : U238 ( years) ……….Ra226 (1622 years) …………. Bi214 Th232 ( years) … Ra228 (6.7 years)…Th228 (1.9 years)… Tl208 Elimination needed

Conclusion on Kurchatov-ITEP production: 1- remaining pollution of radioelements : Ra226 gives the Bi214 contamination 3 mBq/kg in the second kilo, 100 times too high Ra228 and Th228 gives the Tl208 contamination so 3 mBq/kg is a factor of 1000 too high for a source of SuperNEMO Ru106 is a beta emitter of Q ~ 3 MeV so pollution is catastrophic ! (20 mBq/kg) 2- need of « new producers » : ECP-Krasnoyarsk contacts

ECP-ILIAS meeting Orsay, March 9-10, 2006 Participants : Dmitry Kononov, Yuri Kulinich, Elena Nikitina, ECP-Krasnoyarsk Serge Jullian, Dominique Lalanne, Xavier Sarazin, LAL-Orsay Alexander Barabash, ITEP-Moscow Goal of the meeting study of a possible production of enriched 82Se in the ECP-Krasnoyarsk facility in order to test the level of purity of the final product and comparison to the level needed for the next generation of Double Beta experiment.

Yuri Kulinich presented the possibilities in ECP-Krasnoyarsk. For hundreds of kilograms it is without problems, the facility has the goal of mass production. For example it is ~ 30% of Russian enriched Uranium production and ECP is largest producer of stable isotopes in the world. There are different units and the one devoted to enriched Selenium will be a new one, never used before, so in principle with a low level of radio- impurities. This facility is closely connected to units for chemical purification and chemical treatment. Each new isotope needs special equipment and there is for each a special unit dedicated to.

Dmitry Kononov is an expert in the chemical treatment of Selenium. For the current Selenium production the level of chemical impurities at the output of the facility are the following : Bismuth : g/g ( = 5000  Bq/kg if…) Thallium : g/g ( = 400  Bq/kg if…) (if… = supposing chain at equilibrium)

Tender in June 2006 for a production of 1.5 kilo of enriched Se82 SURPRISE : ECP-Krasnoyarsk… …and a second answer : Chemgas (France) Choice done for Chemgas (better price) According the procedure, not possible to make a different choice Need of a new order to ECP, but of lower amount of money and a new funding, ILIAS being not enough

ILIAS-JRA2 Purification of Selenium Chemical purification at INL (Idaho National Laboratory) results of sample of natural selenium purification of the first kilo of ITEP-Kurchatov Physical purification Kurchatov team IChHPS team

John Baker new developments (updated September 2006) Tests on natural Se before purification of the batch of enriched Se82 Purification for Ru : adding natural Ru to 485 ppb then purification and redissolution of Se level of Ru = 3ppb purification factor = 160 Test of losses of Se : none in dissolution of nitric acid, drying down and redissolution in HCl and barium sulfate precipitation Reduction of Se to metal : not 100% but can be worked around by concentration the Se in solution (similar to Mo). No problem Purification of the batch of enriched Se82 : October 2006 To be finished beginning of 2007

Mikhail Churbanov, Institute of Chemistry of High Purity Substances/ Russian Academy of Sciences (IChHPS/RAS), Nishny Novgorod Remind : the level to be reached for SuperNEMO is 10  Bq/kg for Bi214 and 2  Bq/kg for Tl208. Mikhail Churbanov, Director of IChHPS, presented the studies of the purification of Selenium and the installations existing at IChHPS. This Institute has been purifying Selenium since 20 years and has a deep knowledge of the physical and chemical processes involved in chemistry and distillation. Distillation has to deal with different compounds of Selenium as cycloSe8, katenopoly-Se and polycyclo-Se in chemical equilibrium. Melting and boiling points depend on the structure. With radium it has to be taken into account the existence of compound as RaSe. At IChHPS various techniques are used for distillation : one-stage distillation multistage distillation rectification (multistage in one run) In the case of rectification the level that can be reached for Uranium traces is less than g/g (corresponding to 1  Bq/kg if the chain is at equilibrium). This method seems to be appropriate to the requirements of the double beta source we have in project.

ILIAS-JRA2 Measurements of residual radioactivity in selenium batch Matthias Laubenstein at Gran Sasso (Germanium crystal) Vassily Kornoukhov at INR (with proportionnal counters measuring radon emanation, but so, only for Bi214) Warsaw group : TPC imaging, possible for Radon (Rn222) and Thoron (Rn220)

Matthias Laubenstein

If it is possible to hope a level of 300  Bq/kg for Bi and Tl at the production level (as mentionned before) A factor of 50 on Ra226 will fit the specification for Bi214 A factor of 10 (but may be it’s better, here only limits) for Ra228 is much too small for Tl208, we need a factor 100

To prove the possibility of purification by a factor of 100 for Tl208 We must choose a new sample of natural Se with a greater level of Tl208 before purification, then purify it…then measure it.. … or measure the sample purified by John Baker, as we have only limits, by a more sensitive technique, but how ??? Only possible with BiPo !