ILIAS-JRA2Production 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)

Masse (kg)

Time(h) 40K 60Co 137Cs 238U 235U 226Ra 228Th 228Ra 106Ru

82Se powder

1 300 < 14 0.8 ± 0.3 0.9 ± 0.3 90 ± 15 2.9 ± 5 < 1.5 3.7 ± 7 1.6 ± 5 24 ± 3

First kilogram, reminder:

Sample (mBq/k)

Masse (kg)

Time(h) 40K 60Co 137Cs 238U 235U 226Ra 228Th 228Ra 106Ru

82Se powder

1 530 66 ± 20 0.7 ± 0.3 < 0.4 87 ± 14 4.6 ± 0.5 3.0 ±

0.74.3 ± 0.7 2.6 ±

1.016 ± 3

Collaboration meeting NEMO/SuperNEMO, Prague, November 2004

November 2004

To keep in mind :

U238 (4.5 109 years) ……….Ra226 (1622 years) …………. Bi214

Th232 (13.9 109 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 contamination3 mBq/kg in the second kilo, 100 times too high

Ra228 and Th228 gives the Tl208 contamination so3 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 meetingOrsay, March 9-10, 2006

Participants : Dmitry Kononov, Yuri Kulinich, Elena Nikitina, ECP-Krasnoyarsk

Serge Jullian, Dominique Lalanne, Xavier Sarazin, LAL-OrsayAlexander 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 ofthe facility are the following :

Bismuth : 40. 10-11 g/g ( = 5000 Bq/kg if…)Thallium : 7. 10-11 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 ppbthen purification and redissolution of Selevel of Ru = 3ppbpurification factor = 160

Test of losses of Se : none in dissolution of nitric acid, drying down and redissolutionin 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 distillationmultistage distillation

rectification (multistage in one run)In the case of rectification the level that can be reached for Uranium traces is less than 9.10-14 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 levelof 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 !