Stefano Pirro, IDEA Meeting -Zaragoza November 7, Nd Project High Temperature Thermistors News about NdGaO 3 Scintillating Bolometers Conclusions & Prospect Results on NdGaO 3 Neodymium Garnet

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 High temperature thermistors Since the optimum operation temperature for the Nd bolometers is not predictable a priori, several NTD (Neutron Transmutation Doped) thermistors with different sensitivities and therefore optimized for different operation temperatures were prepared (thanks to the collaboration with E. Haller, LBL, and co-workers).

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 NdGaO 3 We tested this compound several times during 2004 & 2005 We succeed to reach “low temperatures” (~ 17 mK) However the assembled bolometer showed a “strange” behavior We was able to see thermal injected power We wasn’t able to recognize Particle pulses Down-conversions of ballistic phonons to thermal phonons is suppressed/trapped

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Phonon opacity….? Interaction between phonons and nuclear magnetic moments could explain this behavior. It is not easy to evaluate the mean free path of a ballistic phonon in the NdGaO 3 crystal because the spin-phonon interaction depends crucially on fine-structure parameters that needs to be measured. The only way to avoid this interaction, and to effectively test the theory, is to eliminate in the crystal the isotopes with nuclear spins, i.e. 143 Nd (12%) and 145 Nd (8%) through a suitable enrichment in 150 Nd.

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 NdGaO 3 - thin sample The Idea is to try to evaluate roughly the enrichment needed to avoid this effect. We assembled a very small NdGaO 3 bolometer by cutting the small sample 13x13x2 mm 3 NdGaO 3 (2.5 g) Thermistor Heater

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 NdGaO 3 - thin sample-results 1 After 3 weeks the temperature of the bolometer is ~ 13 mK The detector is presently LNGS The detector works as bolometer We are able to see ~ 70 keV of thermal injected power However…….

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 NdGaO 3 - thin sample-results 2 Heater pulseParticle Pulse There are several classes of pulses The heater pulses are the fastest  Structure ? 238 U  g/g 232 Th  g/g

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Neodymium garnet Neodymium garnet (Nd 3 Ga 5 O 12 ) is somehow “similar” to neodymium gallate but easier to grow 18 mm height x 13 mm diameter Nd-Garnet The detector is presently LNGS After 3 weeks the temperature of the bolometer is ~ 33 mK No pulses are observed We will test a new Nd compound ( NaNd(MoO 4 ) 2 ) within the next run in the Hall C cryostat

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Innovative Techniques Several tests were made in the R&D during the lasts months The idea is to move towards a active background rejection Double readout heat - light Nuclei with Q-Value above the 208 Tl -  line 100 Mo 3034 keV 48 Ca 4271 keV 116 Cd 2802 keV

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 First “LARGE” mass high RESOLUTION scintillating bolometer for DBD A very impressive result was indeed obtained as a by-product. The idea was to measure the thermal neutrons flux inside the CUORE R&D cryostat using a CdWO 4 crystal, via the ( 113 Cd,n)  reaction. 3x3x2 cm 3 CdWO 4 (140g) 6.6 cm dia 1 mm thick Ge Q  ( 116 Cd)=2802 keV

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Setup Mixing ChamberStainless steel wire First damping mass (Roman Lead) Cuore Radioctivity test run (II Damping stage) Light Detectors Very “un-clean” setup”

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Calibration results 0.9 % 2615 keV  3 % 2615 keV 232 Th + 56 Co Calibration Heat Scitillation

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Background measurement During April a background measurement was performed with the RAD detector The measure was optimized for the TeO 2 crystals 417 h live time measurement arXiv:nucl-ex/

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Actual Energy resolution At the end of the radioactive run we recognized that there were an error in the electronic setup of Cd We therefore performed a short calibration optimizing the CdWO 4 bolometer % FWHM

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 New Run 4x4x3 cm 3 LiF Crystal 3x3x2 cm 3 CdWO 4 crystal 2 cm height 2 cm dia ZnSe crystal Preliminary results  E FWHM LD =25 eV Light Detector ZnSe shows large Scintillation light

Stefano Pirro, IDEA Meeting -Zaragoza November 7, 2005 Conclusions Neodimuim-based Detectors/Bolometers shows clearly the difficulties of this compound The Nd enrichment could be, maybe, not achievable within the needed level The “new” implementation of scintillating bolometers clearly shows the easy feasibility of a “new” powerful experiment Lot of effort is needed in order to identify a suitable scintillating compound