Post on 02-Jan-2016
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
150Nd Project
• High Temperature Thermistors
• News about NdGaO3
• Scintillating Bolometers
• Conclusions & Prospect
• Results on NdGaO3
• 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
NdGaO3
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 NdGaO3 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. 143Nd (12%) and 145Nd (8%) through a suitable enrichment in 150Nd.
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
NdGaO3- thin sample
The Idea is to try to evaluate roughly the enrichment needed to avoid this effect.
We assembled a very small NdGaO3 bolometer by cutting the small sample
13x13x2 mm3 NdGaO3 (2.5 g)
ThermistorHeater
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
NdGaO3- thin sample-results 1
After 3 weeks the temperature of the bolometer is ~ 13 mK
The detector is presently running @ LNGS
The detector works as bolometer
We are able to see ~ 70 keV ofthermal injected power
However…….
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
NdGaO3- thin sample-results 2
Heater pulse
Particle Pulse
There are several classes of pulses
The heater pulses are the fastest
Structure ?
238U 710-7 g/g
232Th 310-8 g/g
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
Neodymium garnet
Neodymium garnet (Nd3Ga5O12) is somehow “similar” to neodymium gallate but easier to grow
18 mm height x 13 mm diameter Nd-Garnet
The detector is presently running @ LNGS
After 3 weeks the temperature of the bolometer is ~ 33 mK
No pulses are observed
We will test a new Nd compound ( NaNd(MoO4)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 cryostat @LNGS during the lasts months
The idea is to move towards a active background rejection
Double readout heat - light
Nuclei with Q-Value above the 208Tl - line
100Mo 3034 keV
48Ca 4271 keV
116Cd 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 CdWO4 crystal, via the (113Cd,n) reaction.
3x3x2 cm3 CdWO4
(140g)
6.6 cm dia 1 mm thick Ge
Q(116Cd)=2802 keV
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
Setup
Mixing Chamber
Stainless steel wire
First damping mass(Roman Lead)
Cuore Radioctivitytest run
(II Damping stage)
Light Detectors
Very “un-clean” setup”
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
Calibration results
0.9 % FWHM @ 2615 keV
3 % FWHM @ 2615 keV
232Th + 56Co Calibration
HeatScitillation
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 TeO2 crystals
417 h live time measurement
arXiv:nucl-ex/0510074
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
Actual Energy resolutionAt 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 CdWO4 bolometer.
0.24 % FWHM
Stefano Pirro, IDEA Meeting -Zaragoza November 7 , 2005
New Run4x4x3 cm3 LiF Crystal
3x3x2 cm3 CdWO4 crystal2 cm height 2 cm dia ZnSe crystal
Preliminary results
EFWHM 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