561 research outputs found
A bolometric measurement of the antineutrino mass
High statistics calorimetric measurements of the beta spectrum of 187Re are
being performed with arrays of silver perrhenate crystals operated at low
temperature. After a modification of the experimental set-up, which allowed to
substantially reduce the background of spurious counts and therefore to
increase the sensitivity on the electron antineutrino mass, a new measurement
with 10 silver perrhenate microbolometers is running since July 2002. The
crystals have masses between 250 and 350 micrograms and their average FWHM
energy resolution, constantly monitored by means of fluorescence X-rays, is of
28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg
effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5
{syst} eV, while the half lifetime of the decay is found to be 43.2 +/-
0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far
for 187Re. From the fit of the Kurie plot we can deduce a value for the squared
electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The
corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let
A linear, low-noise, low-power optocoupler amplifier for bolometric detectors
We present an optocoupler with di⁄erential inputs and balanced output, which was realized to make galvanic decoupling in a bolometric detector read-out chain. The circuit configuration incorporates a true di⁄erential optocoupled feedback, with low bias current in LEDs and photodiodes. Large Common Mode (CMRR) and Power Supply (PSRR) Rejection Ratio, low crossover distortion, high dynamic range, low noise and power dissipation have been achieved. ( 1998 Elsevier Science B.V. All rights reserved
Large area Si low-temperature light detectors with Neganov-Luke effect
Next generation calorimetric experiments for the search of rare events rely
on the detection of tiny amounts of light (of the order of 20 optical photons)
to discriminate and reduce background sources and improve sensitivity.
Calorimetric detectors are the simplest solution for photon detection at
cryogenic (mK) temperatures. The development of silicon based light detectors
with enhanced performance thanks to the use of the Neganov-Luke effect is
described. The aim of this research line is the production of high performance
detectors with industrial-grade reproducibility and reliability.Comment: 4 pages, 2 figure
Measuring thermistor resistance with very low d.c. power dissipation
Abstract A very simple and efficient procedure for measuring thermistor resistances at very low temperatures (down to 5 mK) with d.c. bias voltages is presented. The measurements can be performed with a d.c. power dissipation in the thermistors as low as 10 −18 W or less, as required by the extreme thermistor sensitivity to small heating effects. In particular this method suppresses the effects of the input current of the amplifier used for the measurement. We are using this procedure for the automatic characterization of thermistors with impedances up to 10 9 Ω at temperatures as low as 10 mK
How to improve the sensitivity of future neutrino mass experiments with thermal calorimeters
Abstract In this paper we discuss the perspectives for a new generation of neutrino mass experiments using thermal detectors to reach interesting sensitivities before and after the KATRIN experiment. By scaling the performance of the present Milano neutrino mass experiment with Monte Carlo simulations, we show how a new experiment can validate the present limit of few eV set by spectrometers before the KATRIN experiment starts. We also show how such a result can be used to design a very large thermal detector experiment to reach sensitivities beyond the KATRIN expected one
The Milano-Gran Sasso double beta decay experiment: Toward a 20-crystal array
Abstract TeO2 thermal detectors are being used by the Milano group to search for neutrinoless double beta decay of 130Te. An upper limit for neutrinoless decay half life of 2.1 × 1022 yr at 90% CL obtained with a 334 g TeO2 detector has been previously reported. To improve the sensitivity of the experiment an array of twenty 340 g TeO2 crystals will be realised in the next future. As a first step toward the realisation of that experiment a 4 crystal detector has been tested in the Gran Sasso refrigerator. Detector performances, data acquisition and analysis are discussed
A programmable front-end system for arrays of bolometers
We report on a new front-end system developed to readout an array of large mass bolometers. The front-end allows setting all the necessary parameters for each detector by remote control. A special circuit, also "red remotely, has been developed in order to adjust the output voltage, allowing the DC coupling to the detector. ( 2000 Elsevier Science B.V. All rights reserved
A search for neutrinoless double beta decay of 130Te with a thermal detector
Abstract A 73.1 g TeO2 bolometric detector has been operating for more than two months at about 16 mK in a specially constructed low activity dilution refrigerator installed in the Gran Sasso Underground Laboratory and shielded against environmental radioactivity. Its energy resolution is comparable with that of a Ge diode. A spectrum of the thermal pulses collected in 1389 h of effective running time shows no evidence for neutrinoless double beta decay of 130Te. The corresponding lower limit of the lifetime is three orders of magnitude more stringent than those obtained for the some nucleus with conventional techniques. It also exceeds the value for the inclusive (two neutrino and neutrinoless) lifetime obtained by geochemical searches. Double beta decay of 130Te has therefore to be attributed mainly to the two neutrino channel
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