Stefano Pirro, IDEA Meeting –Milano November Status of the scintillating bolometer program Scintillating Bolometers Background rejection capabilities Interesting Compounds Future Prospects First tests

Stefano Pirro, IDEA Meeting –Milano November Some remarks The activity of this task was initially dedicated to the development of Nd based bolometers. Unfortunately the results obtained in the first 2 years were not encouraging Therefore the activity of the task was re-planned (since April 2006) but keeping the spirit of the task: the use of the bolometric technique in order to study promising candidates for neutrinoless double beta decay with high Q-value (as 150 Nd), such as 116 Cd and 100 Mo

Stefano Pirro, IDEA Meeting –Milano November Principles of operation Thanks to the different Quenching Factor ,  / , and neutrons can be easily identified  =C/G  T=  E/C

Stefano Pirro, IDEA Meeting –Milano November Environmental “underground” Background Background rejection capabilities I CUORICINO Background 130 Te 76 Ge 100 Mo 116 Cd (External Contaminations)

Stefano Pirro, IDEA Meeting –Milano November Background rejection capabilities II (Internal Contaminations) Thanks to Bi-Po’s and Beatles internal contaminations do not play a significant role BI-Po Bi-Tl BEATLE Does not hold for 234 Pa (Q=2195 keV)

Stefano Pirro, IDEA Meeting –Milano November Our Setup - I 3x3x2 cm 3 CdWO 4 (140g) 6.3 cm dia 1 mm thick Ge Q  ( 116 Cd)=2802 keV

Stefano Pirro, IDEA Meeting –Milano November Our Setup - II 17 g CaMoO cm diam 3 cm height CaF 2 3x3x2 cm 3 CdWO 4 Light detector

Stefano Pirro, IDEA Meeting –Milano November Calibration results on CdWO 4 0.2% 2615 keV2.9 % 2615 keV 232 Th + 56 Co Calibration Heat Scitillation 2.9% FWHM is the best result ever achieved with CdWO 4 as scintillator

Stefano Pirro, IDEA Meeting –Milano November Background measurement on CdWO 4 During last year a long Bg measurement was performed with the RAD detector The measure was optimized for the TeO 2 crystals 440 h live time measurement

Stefano Pirro, IDEA Meeting –Milano November CdWO 4 - some considerations

Stefano Pirro, IDEA Meeting –Milano November CdWO 4 - some considerations II E-rotated  E rotaded =Heat cos  + Light sin  2615 improves by ~ 40 % !!!!!

Stefano Pirro, IDEA Meeting –Milano November Light Signal [au] CaMoO g sample 147 Sm (ext) 238 U 226 Ra 210 Po 222 Rn 224 Ra 214 Bi- 214 Po (  +  /  ) 218 Po --

Stefano Pirro, IDEA Meeting –Milano November Contaminations Both series of 238 U and 232 Th are observed, but both of them are broken at Radium 238 U series 238 U 7.6  0.8 mBq/kg (0.61  0.06) g/g 226 Ra 107  3 mBq/kg (0.86  0.02) g/g ** (broken series) 232 Th series 232 Th 0.17  0.12 mBq/kg (4.2  3) g/g 228 Ra 4.6  0.6 mBq/kg(1.13  0.14) g/g** (broken series) **(equivalent to parent in case of secular equilibrium)

Stefano Pirro, IDEA Meeting –Milano November Future developments CdWO 4 crystals are good (apart 113 Cd) and extremely radiopure We plan to make a “pilot experiment” with an array of 4 crystals within Regarding Mo is more complicated…. Molybdates crystal are not so developed Molybdates crystal are not so clean We found a different CaMoO 4 supplier and we have a new large sample (97 g) From HPGE measurements we know that the radiopurity is a factor 3.3 better with Tespect to the 17.4 g sample This new crystal will be tested in the next CUORE R&D run This kind of research is funded by INFN for , OUTSIDE (parallel to) CUORE