A powerful tool to determine the effective electron-neutrino mass is the calorimetric measurement of the energy released in a nuclear beta decay. Performing a precision measurement of the end point ...of the Electron Capture decay spectrum of 163Ho, HOLMES aims at pushing down the sensitivity on the neutrino mass below 1 eV. In its final configuration HOLMES will deploy an array of 1000 microcalorimeters based on Transition Edge Sensors with gold absorbers in which the 163Ho will be ion implanted. The best technique to easily read out such a number of detector with a common readout line is the microwave frequency domain multiplexing. Therefore, the TESs are coupled to multiplexed rf-SQUIDS operated in flux ramp modulation for linearization purposes. The rf-SQUIDS are then coupled to superconducting quarter wavelength resonators in the GHz range, from which the modulating signal is finally recovering using software defined radio techniques. In the last two years an extensive R&D activity has been carried out in order to maximize the multiplexing factor while preserving the performances of each detector which fulfil the HOLMES requirements ( i.e. an energy resolution of few eV and a time-resolution of a few microseconds). We report here the progress made towards the characterization of the multiplexing system together with the results of the characterization of the HOLMES detectors.
Status of the HOLMES detector development Nucciotti, A.; Alpert, B.; Becker, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
Odprti dostop
HOLMES is a new experiment to directly measure the neutrino mass with a sensitivity as low as 0.4eV. HOLMES will perform a calorimetric measurement of the energy released in the electron capture ...decay of 163Ho. HOLMES will deploy a large array of low temperature microcalorimeters with implanted 163Ho nuclei. HOLMES baseline detector is an array of 1000 microcalorimeters each with an implanted 163Ho activity of about 300 Bq, an energy resolution FWHM of about 1eV at the spectrum end-point (Q≈2.5 keV), and a time resolution of about 1μs. Matching these performances requires a careful optimization of all components, from the microcalorimeters to the signal processing algorithms. We outline here the project technical challenges and the present status of the development.
Low temperature thermal detectors with particle identification capabilities are among the best detectors for next generation experiments for the search of neutrinoless double beta decay. Thermal ...detectors allow to reach excellent energy resolution and to optimize the detection efficiency, while the possibility to identify the interacting particle allows to greatly reduce the background. Tellurium dioxide is one of the favourite compounds since it has long demonstrated the first two features and could reach the third through Cherenkov emission tagging 1. A new generation of cryogenic light detectors are however required to detect the few Cherenkov photons emitted by electrons of few MeV energy. Preliminary measurements with new Si light detectors demonstrated a clear event-by-event discrimination between alpha and beta/gamma interactions at the 130Te neutrinoless double beta decay Q-value (2528 keV).
Assessing the absolute neutrino mass scale is one of the major challenges in particle physics and astrophysics nowadays. A powerful tool to directly estimate the effective electron neutrino mass ...consists in the calorimetric measurement of the energy released within a nuclear beta decay. The progresses made over the last few decades on low-temperature detector technologies have permitted to design experiments with expected sensitivities on the neutrino mass below 1 eV/c 2 with the calorimetric approach. Despite the remarkable performances in both energy (~ eV at keV) and time resolutions (\sim\! 1\ \mu\text{s}) on the single channel, a large number of detectors working in parallel is required to reach a sub-eV sensitivity. Microwave frequency-domain readout provides a powerful technique to read out large arrays of low-temperature detectors, such as transition edge sensors (TESs) or microwave kinetic inductance detectors (MKIDs). In this way, the multiplex factor is only limited by the bandwidth of the available commercial fast digitizers. The microwave multiplexing system will be used to read out the TES array of the HOLMES experiment, which is made of 1000 163 Ho-implanted microcalorimeters. HOLMES is a new experiment that aims to measure the electron neutrino mass by means of the electron capture decay of 163 Ho with an expected sensitivity of the order of the eV/c 2 .
For experiments with high arrival rates, reliable identification of nearly-coincident events can be crucial. For calorimetric measurements to directly measure the neutrino mass such as HOLMES, ...unidentified pulse pile-ups are expected to be a leading source of experimental error. Although Wiener filtering can be used to recognize pile-up, it suffers errors due to pulse-shape variation from detector nonlinearity, readout dependence on sub-sample arrival times, and stability issues from the ill-posed deconvolution problem of recovering Dirac delta-functions from smooth data. Due to these factors, we have developed a processing method that exploits singular value decomposition to (1) separate single-pulse records from piled-up records in training data and (2) construct a model of single-pulse records that accounts for varying pulse shape with amplitude, arrival time, and baseline level, suitable for detecting nearly-coincident events. We show that the resulting processing advances can reduce the required performance specifications of the detectors and readout system or, equivalently, enable larger sensor arrays and better constraints on the neutrino mass.
The determination of the neutrino mass is still an open issue in particle physics. The calorimetric measurement of the energy released in a nuclear beta decay allows measuring the whole energy, ...except the fraction carried away by the neutrino: due to the energy conservation, a finite neutrino mass m ν causes the energy spectrum to be truncated at Q-m ν , where Q is the transition energy of the decay. The electron capture of 163 Ho (Q ~ 2.5 keV) is an ideal decay, due to the high fraction of events close to the endpoint (i.e., the maximum energy of the relaxation energy spectrum). In order to achieve enough statistics, a large number of detectors (~10 4 ) are required. Superconducting microwave microresonators are detectors suitable for large-scale multiplexed frequency-domain readout, with theoretical energy and time resolution on the order of electronvolts and microseconds, respectively. Our aim is to develop arrays of microresonator detectors applicable to the calorimetric measurement of the energy spectrum of 163 Ho. Currently, a study aimed at the selection of the best design and material for the detectors is in progress. In order to obtain low-Tc detectors, with Tc ranging between ~0.5 and 2 K, different Ti/TiN (titanium nitride) multilayer films were produced. The reduced Tc was obtained by superposing thin layers of stoichiometric TiN to pure Ti layers, and the Tc was tuned by varying the ratio between the thickness of the layers. In this contribution, a comparison between the measurements (critical temperature, gap parameter, and X-ray energy spectra) made with stoichiometric and substoichiometric TiN and Ti/TiN multilayer film microresonators is presented.
Preliminary Results of the MARE Experiment Ferri, E.; Bagliani, D.; Biassotti, M. ...
Journal of low temperature physics,
09/2014, Letnik:
176, Številka:
5-6
Journal Article
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The microcalorimeter array for a rhenium experiment (MARE) project aims at the direct and calorimetric measurement of the electron neutrino mass with sub-eV sensitivity. The design is based on large ...arrays of thermal detectors to study the beta decay of
187
Re and the electron capture of
163
Ho. One of the activities of the project, MARE 1 in Milan, has started in Milan using one array of 6
×
6 silicon implanted thermistors equipped with AgReO
4
absorbers. The purposes of MARE 1 in Milan are to achieve a sensitivity on the neutrino mass of a few eV and to investigate the systematics of
187
Re neutrino mass measurements, focusing on those caused by the beta environmental fine structure and the beta spectrum theoretical shape. In parallel, the MARE collaboration is performing an R&D work for producing absorbers embedded with radioactive metal
163
Ho. We report here the status of MARE using Re as beta source and the preliminary results obtained with
163
Ho.
The determination of the neutrino mass is still an open issue in particle physics. The calorimetric measurement of the energy released in a nuclear beta decay allows to measure all the released ...energy, except the fraction carried away by the neutrino: a finite neutrino mass m
ν
causes the energy spectrum to be truncated at Q
-
m
ν
, where Q is the transition energy. The electron capture of
163
Ho (Q
∼
2.5 keV) results to be an ideal decay. In order to achieve enough statistics, a large number of detectors (
∼
10
4
) is required. Superconducting microwave microresonators are detectors suitable for large-scale multiplexed frequency domain readout, with theoretical energy and time resolution of
∼
eV and
∼
μ
s. Our aim is to develop arrays of microresonator detectors applicable to the calorimetric measurement of the energy spectra of
163
Ho. Currently, a study aimed to the selection of the best design and material for the detectors is in progress. In this contribution, a comparison between the measurements (critical temperature, gap parameter, quasiparticle recombination time and X-ray energy spectra) made with stoichiometric, sub-stoichiometric TiN and Ti/TiN multilayer films are presented.
The projected background for the CUORE experiment Alduino, C.; Avignone, F. T.; Azzolini, O. ...
The European physical journal. C, Particles and fields,
08/2017, Letnik:
77, Številka:
8
Journal Article
Recenzirano
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The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of
130
Te with an array of 988 TeO
2
bolometers operating at temperatures ...around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the
130
Te decay half-life of 9
×
10
25
years after 5 years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10
-
2
counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of
130
Te is expected.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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