Status of the scintillating bolometer
program
• Scintillating Bolometers
• Background rejection capabilities
• First tests
• Interesting Compounds
• Future Prospects
Stefano Pirro, IDEA Meeting –Milano November 10 2006
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 150Nd), such as 116Cd and 100Mo
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Principles of operation
=C/G
T=E/C
Thanks to the different Quenching Factor  ,/, and neutrons can be easily identified
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Background rejection capabilities I
(External Contaminations)
76Ge
130Te
116Cd
100Mo
CUORICINO Background
Environmental “underground” Background
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Background rejection capabilities II
(Internal Contaminations)
BI-Po
BEATLE
Bi-Tl
Thanks to Bi-Po’s and Beatles internal contaminations do not play a significant role
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Does not hold for 234Pa (Q=2195 keV)
Our Setup - I
6.3 cm dia 1 mm thick Ge
3x3x2 cm3 CdWO4
(140g)
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Q(116Cd)=2802 keV
Our Setup - II
3x3x2 cm3 CdWO4
3.2 cm diam 3 cm height CaF2
Light detector
17 g CaMoO4
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Calibration results on CdWO4
232Th
+ 56Co Calibration
Heat
Scitillation
2.9
0.2%
% FWHM
FWHM @
@ 2615
2615 keV
keV
2.9% FWHM is the best result ever achieved with CdWO4 as scintillator
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Background measurement on CdWO4
During last year a long Bg measurement was performed with the RAD detector
The measure was optimized for the TeO2 crystals
440 h live time measurement
Stefano Pirro, IDEA Meeting –Milano November 10 2006
CdWO4- some considerations
Stefano Pirro, IDEA Meeting –Milano November 10 2006
CdWO4- some considerations II
Erotaded=Heat cos + Light sin

FWHM @ 2615 improves by ~ 40 % !!!!!
Stefano Pirro, IDEA Meeting –Milano November 10 2006
CaMoO4 -17.4 g sample
Light Signal [au]
222Rn
210Po
238U
224Ra
218Po
226Ra
-
147Sm
(ext)
214Bi-214Po
Stefano Pirro, IDEA Meeting –Milano November 10 2006
(+/)
Contaminations
Both series of 238U and 232Th are observed, but both of them are broken at Radium
7.6  0.8 mBq/kg
(broken series)
226Ra 107  3 mBq/kg
238U
238U
series
232Th
232Th
series
0.17 0.12 mBq/kg
(broken series)
228Ra 4.6 0.6 mBq/kg
(0.61  0.06) 10-9 g/g
(0.86  0.02) 10-8 g/g **
(4.2  3) 10-11 g/g
(1.13  0.14) 10-9 g/g**
**(equivalent to parent in case of secular equilibrium)
Stefano Pirro, IDEA Meeting –Milano November 10 2006
Future developments
CdWO4 crystals are good (apart 113Cd) and extremely radiopure
We plan to make a “pilot experiment” with an array of 4 crystals within 2007.
Molybdates crystal are not so developed
Regarding Mo is more complicated….
Molybdates crystal are not so clean
We found a different CaMoO4 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 2007-2008, OUTSIDE (parallel to) CUORE
Stefano Pirro, IDEA Meeting –Milano November 10 2006