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I ntegrated L arge I nfrastructures for A stroparticle S cience. ILIAS-JRA2. Production of enriched Selenium 2 kilos « ITEP-Kurchatov » New contacts with ECP-Krasnoyarsk New production from Tomsk What’s next ?. Second kilogram of enriched Selenium “ITEP-Kurchatov”

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Integrated Large Infrastructures for Astroparticle Science


  • Production of enriched Selenium

  • 2 kilos « ITEP-Kurchatov »

  • New contacts with ECP-Krasnoyarsk

  • New production from Tomsk

  • What’s next ?

Second kilogram of enriched Selenium “ITEP-Kurchatov”

(A. Barabash, L. Sosnin and A. Cheltsov)

22 days of statistics

First kilogram, reminder:

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 : 40. 10-11 g/g ( = 5000 mBq/kg if supposing chain at equilibrium)

Thallium : 7. 10-11 g/g ( = 400 mBq/kg if supposing chain at equilibrium)

So both at a level 100 times too high

Tender in June 2006 for a production of 1.5 kilo of enriched Se82

SURPRISE : ECP-Krasnoyarsk…

…and a second answer : Chemgas -Tomsk

Choice done for Chemgas-Tomst (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

All possible sites in Russia are (and Chemgas is in touch with all of them) :

For Se82, the choice of Chemgas is Tomsk

Actually Alexander Barabash thinks that the 2 kilos tagged « ITEP-Kurchatov »

were produced in Tomsk (September 2006 announcement !). At my last questioning

in June 2006 at Santa Fe, Alexander confirmed me that the 2 physicists of Kurchatov

were doing the job (but I have still no report on this from Kurchatov).

ILIAS work summary with all of them) :

In 2003, what we thought :

1- Selenium was not possible to buy, but as in NEMO 3 we have to rent it

(possible for years…)

2- Kurchatov (via ITEP) was the only producer in our case

So, we did a Convention with ITEP for a rent of 2 kilos

In 2006 what we know :

1- after a meeting in Munich with the Gerda team : it is possible to buy

Selenium as they do for Germanium

2- There is 3 possible plants in Russia, Krasnoyarsk (able to produce hundreds of kg),

Tomsk (almost able of hundred), Kurchatov (for kilograms).

3- there is a French importer (Chemgas) in touch with these 3 centers,

ready to organize meetings with the real producers.

History of the first 2 kilograms of « Kurchatov » with all of them) :

After the first kilogram production, the pollution of Ru should have been

discussed for understanding the origin.

We never had any information on this discussion, and the second kilo

had the same pollution.

Actually, what we discovered in november 2006 :

1- the 2 kilos were not produced in Kurchatov but in Tomsk

2- the information of Ru pollution was never sent to Tomsk

ILIAS-JRA2 with all of them) :

Purification of Selenium

Chemical purification at INL

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) with all of them) :

Next talk from John Baker

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

Next talk from Vasily Kornoukhov

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 mBq/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.

Remind : the level to be reached for SuperNEMO is

10 mBq/kg for Bi214 and 2 mBq/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)

ILIAS-JRA2 Substances/ Russian Academy of Sciences (IChHPS/RAS), Nishny Novgorod

Measurements of residual radioactivity in selenium batch

Matthias Laubenstein at Gran Sasso (Germanium crystal)

Vasily 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)

If it is possible to hope a level of 300 Substances/ Russian Academy of Sciences (IChHPS/RAS), Nishny NovgorodmBq/kg for Bi and Tl at the production level

(as mentionned before)

A factor of 50 on Ra226 fits 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 ???

or…. wait for BiPo !

Remark: This « best Germanium in the world » can reach a sensitivity

of 1 mBq/kg when measuring 1 kg (with a greater statistics, that could be as

low as 500 mBq/kg

To reach the level of mBq/kg, we all know that the BiPo detector is needed but

new developments are possible

Proportional counters and radon degassing (old technique but with new inputs)

(Vasily Kornoukhov, INR)

Development scheduled in 2007

Next talk from Vasily Kornoukhov

TPC with CCD camera with new inputs)

Warsaw group

Possibility of Radon 220 measurement in SuperNEMO gas

Next talk from

Zenon Janas