Status of the Se82 project Selenium production and purification JRA2-ILIAS

1. Status of the Se82 project Selenium production and purification JRA2-ILIAS Prague, April 20th, 2006, IDEA-N4 meeting Dominique Lalanne

2. 82Se production: present status PRESENT STATUS: 1. There is agreement between ITEP and CNRS/IN2P3 about production of 2 kg of 82Se (it was signed in February’05; end of agreement is 31 December 2006). 2. 1-st kg was ready in September’05. 3. 2-nd kg was produced in January’06. To be measured in Laboratoire Souterrain de Modane this April 2006

3. First delivery of 1 kg of enriched Selenium from ITEP Measurement of radio-element traces Conclusions : 228Ra and 228Th give the 208Tl contamination so 2 mBq/kg is a factor of 1000 too high for a source of SuperNEMO 226Ra gives the 214Bi contamination only a limit, so a more precise measurement would be usefull 108Ru is a beta emitter of Q ~ 3 MeV so pollution is catastrophic ! purification !

4. Characteristics of the second kg • Enrichment: 96.7 ± 0.3 % • Other Se isotopes:

5. New opportunities for enrichment Very important contact with ECP (Electro-Chemical Plant, Svetlana) Zelenogorsk (Siberia) • Much easier collaboration with this factory today • 40 kg of enriched 76Ge for GERDA experiment • Possibility of 2 kg of 82Se in this facility (IN2P3 ownership) • Enrichment of 100 kg of 82Se is possible in 3 years at ECP • Present cost: ~ 50 k€ / kg • Distillation of 82Se possible in ECP just after enrichment for highest purity (distillation of 116Cd have been done in NEMO 3) contact also for enrichment of Te in 130Te

6. 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.

7. Yuri Kulinich presented the possibilities in ECP-Krasnoyark. 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.

8. Dmitry Kononov is an expert in the chemical treatment of Selenium. For the current Selenium production the level of chemical impurities at the output are the following : Thallium : 7. 10-11 g/g Bismuth : 40. 10-11 g/g Thorium : 6. 10-11 g/g (240 mBq/kg) Uranium : 3. 10-11 g/g (360 mBq/kg) -----------------------

9. Alexander Barabash (ITEP, Moscow) is responsible of the purity of the post-enrichment process. He will be allowed to spend as much time as needed at the site to give the green light for production in clean conditions. Especially on clean handling in clean air environment and clean conditions, also on some tools or odds and ends being possibly polluted or capable to induce pollution from outside. The possibility of measurements in Modane Laboratory of some parts of the equipment can be used for selection. The agreement can be signed within 2 months for a production of 1 kg by the end of year 2006.

10. INL, Hidaho, USA Selenium purification ILIAS-JRA2

11. Challenge : from NEMO3 to SuperNEMO NEMO3 Backgrounds • External : negligeable • Internal : 208Tl : 60 Bq/kg for 100Mo 300 Bq/kg for 82Se 214Bi : 300 Bq/kg ~ 0,2 evt kg1 y 1 with 2,8<E1+E2<3,2 MeV • 100Mo T1/2 = 7.11 1018 y ~ 0,3 evt kg1 y 1 with 2,8<E1+E2<3,2 MeV • SuperNEMO Background requirement • Internal : 208Tl :2 mBq/kg for 82Se • 214Bi : 10 mBq/kg

12. Matthias Laubenstein future measurement : The present level of sensitivity is 1 mBq/kg (Modane Lab), possibility of a better sensitivity on GeMPI (a few 100 mBq/kg) effective volume of sample chamber ~ 15 l

13. Challenge : from NEMO3 to SuperNEMO NEMO3 Backgrounds • External : negligeable • Internal : 208Tl : 60 Bq/kg for 100Mo 300 Bq/kg for 82Se 214Bi : 300 Bq/kg ~ 0,2 evt kg1 y 1 with 2,8<E1+E2<3,2 MeV • 100Mo T1/2 = 7.11 1018 y ~ 0,3 evt kg1 y 1 with 2,8<E1+E2<3,2 MeV • SuperNEMO Background requirement • Internal : 208Tl :2 mBq/kg for 82Se • 214Bi : 10 mBq/kg

14. New plans for this year : purification of enriched selenium (one kilo) 1 – purification of the second kilo of enriched selenium of ITEP, if the second kilo of ITEP is not polluted with 106Ru Radioactivity of the first kilo of enriched selenium from ITEP 2 – study of elimination of 106Ru

15. Kurchatov Institute, Moscow Selenium distillation ILIAS-JRA2

16. Meeting in Kurchatov Institute November 17 -18th, 2005 Youri Gaponov, Andrey Tikhomirov, Youri Muromkin, Serge Jullian, Dominique Lalanne There is a Kurchatov team with the skill for distillation. Distillation has been done successfully in the past for Cadmium but not for Selenium. Distillation of Selenium should be easier than Cadmium, the melting point being lower for Selenium (200 degrees at atmospheric pressure) than for Cadmium (320 degrees). It can be proposed to make a distillation of natural Selenium to test the process. But for a successful distillation, the product to be used must be pure enough, so before distillation a chemical purification is needed.

17. Purification programme at Kurchatov 1. A choice of a supplier and purchasing of elemental selenium in the amount of several kilograms (the amount will be determined more accurately later, after the program of the distillation process development is fulfilled) 2. Incoming control of impurities (admixtures) in selenium. 3. Sampling of 1 kg of initial selenium for measurements in France. 4. Selection of a purification process, pilot plant design, program of tests. 5. Determination of a tolerated « (purified selenium) / waste » ratio. (For distillation of an enriched product this ratio must be as large as possible). 6. Mounting of the pilot plant. 7. Start-up of the pilot plant 8. Purification of a 1-kg sample 9. test measurements in LSM

18. ILIAS conclusions on production and purification issues: 1- for a mass production of hundreds of kilograms of enriched selenium, the Krasnoyarsk facility seems to be the only one in Russia. 2- a radio-purity level of a few mBq/kg seems hopeless after the production (even with a step of “evaporation”) for 208Tl. 3- it has to be tested a real distillation process: to be done in Kurchatov soon 3- the chemical purification of INL is better than a factor of 6, a more precise measurement should give the real value or a lower limit. If it is reached a factor of 100 that can be correct for SuperNEMO (according the expected level after production in Krasnoyarsk could be of 240 mBq/kg)

19. Conclusions for Se82 project, second year Done : 1- Production of enriched Selenium from ITEP: inappropriate for SuperNEMO 2- Purification in INL : more measurements needed for the answer New agreements for testing : 1- Production in Krasnoyarsk 2- distillation in Kurchatov