1. ILIAS, Jaca, Spain 5 of December 2006 Se-82 purification: how to control the procedure (Bi-214)? Kornoukhov Vasily INR RAS Moscow

2. LAL, Orsay, Spain 1 – 2 of June 2006 SuperNEMO: radiopurity requirements Tl-208 ( 232 Th chain) <= 2  Bq/kg (<= 1.5 ppt of Th-232) B-214 ( 238 U chain) <= 10  Bq/kg (< = 10 ppt of U-238)

3. 238 U 4,51·10 9 y 234 Th 24 d 234m Pa 1,18 min 234 U 2,47·10 5 y 230 Th 8,0 ·10 4 y 226 Ra 1602 y 222 Rn 3,824 d 218 Po 3,05 min 214 Pb 26,8 min         214 Bi 19,7 min  T 1/2 ~ 10 3 - 10 9 y T 1/2 ~ days T 1/2 ~ minutes

4. ILIAS, Jaca, Spain 5 of December 2006 SuperNEMO: dangerous isotopes from 238 U chain Ra-226 We must remove Ra How to check the procedure: Ra: 226 Ra (HPGe: 214 Bi  line, Champagne method)

5. ILIAS, Jaca, Spain 5 of December 2006 SuperNEMO: how to measure/control Ra-226? Radiometric measurements: HPGe, NaI(Tl) Champagne technique: 226 Ra  222 Rn (gas) proportional counter bkg (  ’s particles): ~ 1 events/day  10 -5 Bq/kg of sample ~ 10  Bq/kg of sample

6. ILIAS, Jaca, Spain5 of December 2006 Champagne method: general principle of operation 226 Ra (1622 y)  222 Rn (3,82 days, noble gas)  3  ’s particles 222 Rn ( 3,82 d)  218 Po( 3,05 min)  214 Pb (26,8 min)  214 Bi (19,9 min)  214 Po ( 164  s) We just count number of  – decays with proportional counter of very small volume (~ 1 cm 3 ) and with background of ~ 1 – 0,1 events/day (DL ~ 10 – 1,0  Bq/kg of sample)

7. ILIAS, Jaca, Spain5 of December 2006 Proportional counter Low background miniaturized proportional counter was designed for Ar-37 and Ge-71 counting (Homestake Cl-Ar, GALLEX, SAGE) New version of PC from INR RAS, Moscow ( NIM A349 (1994) 466-472 ) with bkg for  -counting ~ 1 count / 10 days and direct filling with working gas under LN temperature (- 196 o C).

8. ILIAS, Jaca, Spain 5 of December 2006 Champagne method: general scheme (NEMO-3 Collaboration: NIM A469 (2001) 159-163 )

9. ILIAS, Jaca, Spain 5 of December 2006 Champagne method: results (NEMO-3 Collaboration: NIM A469 (2001) 159-163 ) SampleMassmBq/kgmBq/kg of sampleChampagneHPGe Frejus Cd metal200 g0.33 +/- 0.05< 2 Nd 2 O 3 200 g2,3 +/- 0,2< 17 Mo-powder 50 g< 1< 3,3 Mo-foil (AMAX) 11 g1445 +/- 60 1500 +/- 167 HCl1,67 +/- 0,15< 2 HNO 3 < 0,25- H 2 O (DI)< 0,018-

10. ILIAS, Jaca, Spain 5 of December 2006 Extraction set up

11. ILIAS, Jaca, Spain 5 of December 2006 PC is into LN bath (Rn freezing)

12. ILIAS, Jaca, Spain 5 of December 2006 PC calibration

13. ILIAS, Jaca, Spain 5 of December 2006 PC is in well-type NaI(Tl)

15. ILIAS, Jaca, Spain 5 of December 2006 Last stage of Se purification and Rn extraction

16. ILIAS, Jaca, Spain 5 of December 2006 Conclusion SuperNEMO: dangerous isotope from 238 U chain is Bi- 214(Ra-226), A  10  Bq/kg. Emanation (“champagne”) method is well developed in INR RAS The sensitivity is (10  1)  Bq/kg of mass of sample. Emanation (“champagne”) method and purification procedure based on distillation/rectification method could be used as single integrated method/procedure. The extraction system and last stage of distillation/rectification set up could be easy fitted to each other.