Characterization and modeling of a low background HPGe detector Dokania, N.; Singh, V.; Mathimalar, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2014, Letnik:
745
Journal Article
Recenzirano
A high efficiency, low background counting setup has been made at TIFR consisting of a special HPGe detector (~70%) surrounded by a low activity copper+lead shield. Detailed measurements are ...performed with point and extended geometry sources to obtain a complete response of the detector. An effective model of the detector has been made with GEANT4 based Monte Carlo simulations which agrees with experimental data within 5%. This setup will be used for qualification and selection of radio-pure materials to be used in a cryogenic bolometer for the study of Neutrinoless Double Beta Decay in 124Sn as well as for other rare event studies. Using this setup, radio-impurities in the rock sample from India-based Neutrino Observatory (INO) site have been estimated.
A program to develop low temperature (mK) sensors with neutron transmutation doped Ge for rare event studies with a cryogenic bolometer has been initiated. For this purpose, semiconductor grade Ge ...wafers are irradiated with thermal neutron flux from Dhruva reactor at Bhabha Atomic Research Centre (BARC), Mumbai. Spectroscopic studies of irradiated samples have revealed that the environment of the capsule used for irradiating the sample leads to significant levels of 65Zn, 110mAg and 182Ta impurities, which can be reduced by chemical etching of approximately ~50μm thick surface layer. From measurements of the etched samples in the low background counting setup, activity due to trace impurities of 123Sb in bulk Ge is estimated to be ~1Bq/g after irradiation. These estimates indicate that in order to use the NTD Ge sensors for rare event studies, a cooldown period of ~2 years would be necessary to reduce the radioactive background to ≤1mBq/g.
.
Neutrinoless double beta decay is a phenomenon of fundamental interest in particle physics. The decay rates of double beta decay transitions to the excited states can provide input for Nuclear ...Transition Matrix Element calculations for the relevant two neutrino double beta decay process. It can be useful as supplementary information for the calculation of Nuclear Transition Matrix Element for the neutrinoless double beta decay process. In the present work, double beta decay of
94
Zr to the
2
1
+
excited state of
94
Mo at 871.1 keV is studied using a low background
∼
230
cm
3
HPGe detector. No evidence of this decay was found with a 232 g
.
y exposure of natural zirconium. The lower half-life limit obtained for the double beta decay of
94
Zr to the
2
1
+
excited state of
94
Mo is
T
1
/
2
(
0
ν
+
2
ν
)
>
3
.
4
×
10
19
y at 90% C.L., an improvement by a factor of
∼
4
over the existing experimental limit at 90% C.L. The sensitivity is estimated to be
T
1
/
2
(
0
ν
+
2
ν
)
>
2
.
0
×
10
19
y at 90% C.L. using the Feldman-Cousins method.
Development of NTD Ge sensors has been initiated for low temperature (mK) thermometry in The India-based TIN detector (TIN.TIN). NTD Ge sensors are prepared by thermal neutron irradiation of device ...grade Ge samples at Dhruva reactor, BARC, Mumbai. Detailed measurements have been carried out in irradiated samples for estimating the carrier concentration and fast neutron induced defects. The Positron Annihilation Lifetime Spectroscopy (PALS) measurements indicated monovacancy type defects for all irradiated samples, while Channeling studies employing RBS with 2MeV alpha particles, revealed no significant defects in the samples exposed to fast neutron fluence of ∼4×1016/cm2. Both PALS and Channeling studies have shown that vacuum annealing at 600°C for ∼2h is sufficient to recover the damage in the irradiated samples, thereby making them suitable for the sensor development.
A calorimeter set up with very low heat capacity (
∼
20 nJ/K at 100 mK) has been designed using commercial Carbon based resistors. This calorimeter is used to determine the heat capacity of small ...samples of superconducting bolometer absorbers. In particular, we present heat capacity studies of Tin, a bolometer candidate for Neutrinoless Double Beta Decay in
124
Sn, in the temperature range of 60–400 mK.
The specific heat of amorphous polymers, Teflon, Torlon 4203 and Torlon 4301, has been measured in the range of 30-400 mK using thermal relaxation calorimetric technique. The data is consistent with ...the tunneling state models used to explain the observed unusual low temperature specific heat of amorphous polymers. Below 100 mK, the specific heat of Torlon 4301 is ~3 times higher than that of Torlon 4203. Teflon has the lowest specific heat, ~10 times lower than that of Torlon 4301.
The Mini-CAPTAIN liquid argon time projection chamber Taylor, C.E.; Bhandari, B.; Bian, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2021, Letnik:
1001
Journal Article
Recenzirano
Odprti dostop
This manuscript describes the commissioning of the Mini-CAPTAIN liquid argon detector in a neutron beam at the Los Alamos Neutron Science Center (LANSCE), which led to a first measurement of ...high-energy neutron interactions in argon. The Mini-CAPTAIN detector consists of a Time Projection Chamber (TPC) with an accompanying photomultiplier tube (PMT) array sealed inside a liquid-argon-filled cryostat. The liquid argon is constantly purified and recirculated in a closed-loop cycle during operation. The specifications and assembly of the detector subsystems and an overview of their performance in a neutron beam are reported.
Neutron transmutation-doped (NTD) Ge sensors have been prepared by irradiating device-grade Ge with thermal neutrons at Dhruva reactor, BARC, Mumbai. These sensors are intended to be used for the ...study of neutrinoless double beta decay in
124
Sn with a superconducting Tin bolometer. Resistance measurements are performed on NTD Ge sensors in the temperature range 100–350 mK. The observed temperature dependence is found to be consistent with the variable-range hopping mechanism.
•Specific heat of Teflon, Torlon 4203 and Torlon 4301 measured in 30–400mK range.•The present work reports the specific heat of Torlon 4301 for the first time.•Specific heat data of Teflon and Torlon ...4203 has been extended up to 30mK.
The specific heat of amorphous polymers, Teflon, Torlon 4203 and Torlon 4301, has been measured in the range of 30–400mK using thermal relaxation calorimetric technique. The data is consistent with the tunneling state models used to explain the observed unusual low temperature specific heat of amorphous polymers. Below 100mK, the specific heat of Torlon 4301 is ∼3 times higher than that of Torlon 4203. Teflon has the lowest specific heat, ∼10 times lower than that of Torlon 4301.
The feasibility study for searching neutrinoless double beta decay in
124
Sn using cryogenic bolometer has been initiated. For this purpose, a custom-built cryogen-free dilution refrigerator, having ...a large cooling power of 1.4 mW at 120 mK, has been installed at TIFR, India. This paper describes the design, installation and performance of a cryogen-free dilution refrigerator (CFDR-1200). The performance of CFDR-1200 has been analysed using Takano’s model developed for conventional (wet) dilution refrigerators.
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