ECEC process measurement in TGV experiment P ermk

EC/EC process measurement in TGV experiment P. Čermák IEAP CTU in Prague For TGV collaboration: JINR Dubna, Russia CTU Prague, Czech Republic CSNSM Orsay, France RRC - Kurchatov Institute Moscow, Russia CU Bratislava, Slovakia P. Cermak Rez near Prague, December 2005

Outline ● TGV II measurements overview ● Data processing ● Example ● Summary P. Cermak TGV II Rez near Prague, December 2005

TGV • Telescope Germanium Vertical (stack of 16 (32) HPGe detectors) • aims at the study of double beta processes of 48 Ca and 106 Cd (double beta decay, double electron capture) • started in 1996 • located in Modane Underground Laboratory (France) P. Cermak Rez near Prague, December 2005

TGV I ● 16 HPGe detectors of planar type, diameter 40 mm, thickness 6 mm 8 x 48 Ca foils ● 8 x Ca-natural foils ● ~ 1. 35 x 1022 of 48 Ca atoms (1. 08 g) P. Cermak Rez near Prague, December 2005

TGV I open cryostat P. Cermak assembled cryostat, PAs Rez near Prague, December 2005

TGV II purpose: • to improve 48 Ca result obtained by TGV I • to investigate processes in 106 Cd (to focus on EC/EC channel) 2 n. EC/EC: P. Cermak Rez near Prague, December 2005

TGV II spectrometer borated polyethylene SM Dewar cryostat Pb Cu P. Cermak PA 1 m Rez near Prague, December 2005

Detector part of the TGV II 32 HPGe planar detectors 60 mm x 6 mm with sensitive volume: 20. 4 cm 2 x 6 mm Total sensitive volume: 400 cm 3 Total mass of detectors: 3 kg Total area of samples : 330 cm 2 Total mass of sample(s) : 10 25 g E-resolution : 3 4 ke. V @ 60 Co LE-threshold : down to 10 ke. V U+Th<0. 1 ppb Double beta emitters: - samples of 48 Ca: Ca. F 2 + CH 2 ( 75 mg / cm 2 ) - samples of 106 Cd: 106 Cd (~ 50 µm ) P. Cermak Rez near Prague, December 2005

TGV II pedestal P. Cermak open cryostat Rez near Prague, December 2005

TGV II assembled cryostat, PAs P. Cermak Rez near Prague, December 2005

Run overview • 12/03 – 2/04… background, empty cryostat, 1363 hours • 3/04 – 5/04… 13 x 106 Cd + 3 x Cd-nat. , 1768 hours 113 m. Cd, 14 years, Qb=590 ke. V P. Cermak Rez near Prague, December 2005

Run overview (2) ● 5/04 – 6/04… 12 x 106 Cd + 4 x Cd-nat. , 328 hours ● 6/04 – 10/04… 12 x 106 Cd + 4 x Cd-nat. , 2033 hours ● 11/04 – 1/05… 16 x Cd-nat. , 903 hours ● 2/05 – …… 12 x 106 Cd + 4 x Cd-nat. , new sources: P. Cermak 106 Cd . . . 75. 00% 112 Cd . . . 6. 18% 108 Cd . . . 0. 80% 113 Cd. . . 2. 77% 110 Cd . . . 4. 47% 114 Cd. . . 6. 18% 111 Cd . . . 3. 55% 116 Cd. . . 1. 05% Rez near Prague, December 2005

Data processing 1. What we look for: X-rays @21 ke. V from 106 Pd P. Cermak Rez near Prague, December 2005

Data processing (2) 2. What we have: X-rays @23 ke. V from 106 Cd, P. Cermak 3736 hours Rez near Prague, December 2005

3. Zoom to 20 ke. V region (after background reduction) Energy windows: (16 -19) ke. V (19 -22) ke. V (28 -31) ke. V 3736 hours, 106 Cd 5533 hours, 106 Cd P. Cermak Rez near Prague, December 2005

Summary • Full configuration operation (32 channels) • Background, calibration, admixtures in sources • Basic background measurements done (empty cryostat, natural Cd) • From February 2005 long-term measurement with 106 Cd • Negotiation on 106 Cd lease extension First direct measurement of EC/EC process in 106 Cd (~ 6 x 1019 years) P. Cermak Rez near Prague, December 2005