ILIAS JRA2 : WG1+WG2 Se82, production and purification Cascina, November 3rd, 2005Dominique Lalanne

Working group 1 : Production of enriched 82Se 1 - after the agreement IN2P3-ITEP production of 1 kilogram done by October 15th, It has been proceeded to a purification by distillation. The sample has been sent to LAL-Orsay for measurement then in the LSM with the Germanium detector. Enrichment is 97% %, mass is kg. 2 - study of a second type of production done in the same way than enriched germanium production for Gerda. Meeting with the MPI Munich group (Professor Ellen Caldwell) on October 21st, 2005, to define the procedure to be chosen and the Russian groups to be contacted. Project of a production of 2 kilograms for IN2P3 ownership. As in the first production by ITEP the purity level has to be checked and the possibilities of purification on-line by distillation. It is important to have the possibility of technical discussion at the production facility in order to reach the lowest level of radio impurities.

Enrichment of 82 Se Goal: To be able to produce 100 kg of 82 Se  Possibility of 2 kg of 82 Se in this facility ECP (Electro-Chemical Plant, Svetlana) Zelenogorsk (Siberia)  Enrichment of 100 kg of 82 Se is possible in 3 years at ECP Cost today ~ 50 k€ / kg Coordinator: Serge Jullian  Much easier collaboration with this factory today 40 kg of enriched 76 Ge for GERDA experiment  Distillation of 82 Se possible in ECP just after enrichment for highest purity (distillation of 116 Cd have been done in NEMO 3)

3 - ICR facility A report of the request has been done in June 2005 to be send to CEA with help of Bijan Saghai and it is planed to have an appointment at the level of the Direction to discussed the possible involvement of the CEA. We tried to better define a possible programme for an isotope enrichment facility in Europe. Last September the 5th scientific commission of INFN approved and funded a specific program, named ISOPRO, where some members of IDEA are involved. The general idea is to establish a well defined collaboration between institutions in EU (very important is CEA) and, in the ILIAS framework, to promote a general discussion and, eventually, to prepare a road map for a new production facility. In our opinion the final goal can be the preparation of a design study for a big infrastructure in the FP7 of EU.

ICR facility, request to be done to CEA Subject : feasibility study of ICR facility Goal : proposal to be done to FP7 Basic ideas : 1- double beta decay very promising for the absolute mass scale of the neutrino mass. Big community in Europe in this field of research. Common work at the European level with ILIAS. An ICR facility would give access to new isotopes for the next generation of detectors. 2- Such an ICR facility could produce the amount required of typically 100 kilograms of each isotope, currently done only in Russia (100Mo, 82Se, 76Ge, …) and some others which are impossible to produce with other techniques ( 150Nd, 48Ca,…) 3- An ICR facility is a well-known technique, currently working in the US for medicine use. CEA has spend 20 Meuros in 12 years in the 80’s on R&D 4- The CEA has developed such facilities and the expertise is still existing, even if the team is not any more at work on this topic 5- The next generation of double beta experiments could accommodate a facility for producing double beta isotopes if the price is of the order of the current ones for those isotopes enriched by ultracentrifugation in Russia (60 kEuros/kg) 6- fallout for medicine are known (and this is the only goal of the US ICR)

Pierre Louvet estimation : 82Se, 100Mo, 150Nd have natural compositeness between 5% and 10% Following statement OK for all of them: 1- with ICR, the enrichment will be 50% but no more 2- ICR facility could produce 20 to 30 kg per year 3- typical size of the facility: - superconductor coil, diameter 1.1 m - length 7 m - magnetic field 4 Tesla 4- typical price of the equipment : 12 MEuros 5- delay of construction : 4 to 5 years 6- team for operating : 10 people, 2 teams at 8 hours per day

Working Group 2 : Purification of 82Se 1 - work done at INL, Idaho grams have been purified at INL and shipped to LSM to be measured (October 10th) grams of the same batch without purification have been send to LSM and have to be measured for comparison. - study of the structure of the purified powder is also to be done by electronic microscopy. 2 – agreement IN2P3-MHC for buying pure products needed for chemical purification. First step of the agreement is purification of natural Se, then the 1 kilogram of enriched Se82. The agreement correspond to 20 kEuros. 3- pure Barium : John Baker (INL) has not any more pure Barium for making the chemistry. Jean-Louis Reyss (CNRS-Gif sur Yvette) proposes to send the purest he has and will give the procedure to purify it from radium.

4 – study of a device dedicated to measurements of source radiopurity (BiPo detector). This R&D corresponds to ILIAS goal for the qualification of the Se source. Some efforts for such developments have been undertaken during the first year by UCL. The funding decided by IN2P3 will help to reach a real detector working within 3 years. This type of detector is absolutely needed, the current sensitivity of Germanium detectors in LSM being 60  Bq/kg besides the required level for the next generation of detector is ten times lower. The BiPo detector is designed for reaching such a level of 6  Bq/kg 5 – study of new possibilities of source making. This is strongly related to the radiopurity of the ultimate goal of double beta source. This must been done in parallel. This R&D has been also recently funded by IN2P3 and the LAL-Orsay is in charge of the study.

82 Se source foils: production of the foils and control of the Ultra High Purity:  Enrichment, purification and production of 82 Se source foils Ultra High Purities: 208 Tl < 2 mBq/kg and 214 Bi < 10 mBq/kg  Development of new HPGe detectors with a high sensitivity to control the enrichment and purification of 82 Se in the form of powder  Development of a BiPo detector, a dedicated planar detector “à la NEMO” to measure 208 Tl and 214 Bi radiopurity of the 82 Se sources foils before introduction in the detector

R&D for 208 Tl and 214 Bi purity measurement in the source foils Development of a BiPo detector, a dedicated planar detector to measure 208 Tl and 214 Bi radiopurity of the 82 Se sources foils before introduction in the detector Sensitivity required: 5 kg of 82 Se foils in 1 month of measurement 208 Tl < 2  Bq/kg 214 Bi < 10  Bq/kg Goal: 232 Th 212 Bi (60.5 mn) 208 Tl (3.1 mn) 212 Po (300 ns) 208 Pb (stable) 36%   238 U 214 Bi (19.9 mn) 210 Tl (1.3 mn) 214 Po (164  s) 210 Pb 22.3 y 0.021%   BiPo process: electron (  decay) followed by a delayed  emission 212 Bi → 212 Po → 208 Pb Q  ( 212 Bi) = 2.2 MeV

Tracking (wire chamber) Scintillator + PMT Source foil to be measured ee  Prompt e   T 0 Delay  T 1/2 ~ 300 ns E deposited ~ 1 MeV Radon + neutron +  shield Signature electron track in the wire chamber associated to a fired scint + 1 delayed scintillator E deposited ~ 1 MeV near the vertex (T 1/2 = 300 ns) Possible design: planar detector 3 x 4 m 2 Lower scintillator wall: 300 scint. blocks 20 x 20 cm 2 coupled to 300 low radioactivity PMTs Upper wall: 20 bars (3 m long, 20 cm width) double sided readout with 40 low radioactivity PMTs Tracking: 3 layers of drift cells operating in Geiger mode with delayed track ( 214 Bi) Electronic PM: double-range TDC 1  s and 1 ms + ADC With 5 kg of 82 Se source foil (~ 12 m 2, 40 mg/cm 2 ) 50 (e-, delay  ) 212 Bi decays / month 2  Bq/kg of 208 Tl 3 events / month  ~ 6%

proto 1: end 2005 – Jun Location Modane mechanics: Jacques Forget + 2 persons electronics: 1 ingenior Proto 2: Jun – Dec Location Modane mechanics: Jacques Forget + 4 persons electronics: 2 ingenior BiPo detector: 2007 – 2008 Location: to be defined mechanic: larger team electronic: 3 ingenior cabling: 2 persons slow control: 1 ingenior computing: 1 ingenior Clean rooms required in LAL For construction of proto 2 and BiPo detector clean room ~ 20 m 2 in hall IN2P3 class ? mid 2006 ? Prototypes to study background (both will be installed in Modane) Proto 1: end 2005 – Jun Proto 2: Jun – Dec x 1 m 2 → 25 x 2 PMTs (20 x 20 cm 2 ) Electronics: TDC: dynamic range 1  s resoltuion ~ 1 ns ADC up to 4 MeV (60 nC)