We present a novel technique, called DSVP (Discrimination through Singular Vectors Projections), to discriminate spurious events within a dataset. The purpose of this paper is to lay down a general ...procedure which can be tailored for a broad variety of applications. After describing the general concept, we apply the algorithm to the problem of identifying nearly coincident events in low temperature microcalorimeters in order to push the time resolution close to its intrinsic limit. In fact, from simulated datasets it was possible to achieve an effective time resolution even shorter than the sampling time of the system considered. The obtained results are contextualized in the framework of the HOLMES experiment, which aims at directly measuring the neutrino mass with the calorimetric approach, allowing to significally improve its statistical sensitivity.
We present the first performance results obtained with microwave multiplexed Transition Edge Sensors prototypes specifically designed for the HOLMES experiment, a project aimed at directly measuring ...the electron neutrino mass through the calorimetric measurement of the
163
Ho electron capture spectrum. The detectors required for such an experiment feature a high energy resolution at the
Q
–value of the transition, around
∼
2.8 keV, and a fast response time combined with the compatibility to be multiplexed in large arrays in order to collect a large statistics while keeping the pile-up contribution as small as possible. In addition, the design has to be suitable for future ion-implantation of
163
Ho. The results obtained in these tests allowed us to identify the optimal detector design among several prototypes. The chosen detector achieved an energy resolution of (4.5 ± 0.3) eV on the chlorine K
α
line, at
∼
2.6 keV, obtained with an exponential rise time of 14
μ
s. The achievements described in this paper pose a milestone for the HOLMES detectors, setting a baseline for the subsequent developments, aiming to the actual ion-implantation of the
163
Ho nuclei. In the first section the HOLMES experiment is outlined along with its physics goal, while in the second section the HOLMES detectors are described; the experimental set-up and the calibration source used for the measurements described in this paper are reported in Sects.
3
and
4
, respectively; finally, the details of the data analysis and the results obtained are reported in Sect.
6
.
We have developed microwave kinetic inductance detectors suitable for near-IR single-photon counting. Our films are made of titanium and titanium nitride, deposited in a multilayer structure ...Ti/TiN/Ti/TiN with a total thickness of 44 nm. The film has a transition temperature of 1.2 K and a surface kinetic inductance of 34 pH/sq. The resonator was designed with lumped elements and consists of two blocks of interdigitated capacitors connected by a meandered stripe inductor. The resonator resonance frequency is 6.8 GHz, and the internal quality factor is 125,000. The detector is read out with the usual homodyne scheme and calibrated with light pulses produced by a laser diode with wavelength 1550 nm. For the 0- and 1-photon peaks, we measure a FWHM energy resolution of 0.44 eV and 0.56 eV, respectively. This resolution is sufficient to resolve events with up to 4 photons.
The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the decay of ...Formula: see textHo. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted Formula: see textHo nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.
An updated overview of the HOLMES status Borghesi, M.; Alpert, B.; Balata, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2023, Letnik:
1051
Journal Article
Recenzirano
Odprti dostop
HOLMES is an ERC project started in 2014 that will perform a model independent measurement of the neutrino mass with a sensitivity of the order of 1 eV. In order to reach its goal sensitivity, HOLMES ...will use 1000 low temperature microcalorimeters, each implanted with an activity of 300 Bq of 163Ho, performing thus a calorimetric measurement. This contribution presents the recent results achieved that lay the grounds for the low-activity phase of the HOLMES experiment, that will lead to its first limit on the neutrino mass.
This paper describes the production and chemical separation of the 163Ho isotope that will be used in several nuclear physics experiments aiming at measuring the neutrino mass as well as the neutron ...cross section of the 163Ho isotope. For this purpose, several batches of enriched 162Er have been irradiated at the Institut Laue-Langevin high flux reactor to finally produce 6 mg or 100 MBq of the desired 163Ho isotope. A portion of the Er/Ho mixture is then subjected to a sophisticated chemical separation involving ion exchange chromatography to isolate the Ho product from the Er target material. Before irradiation, a thorough analysis of the impurity content was performed and its implication on the produced nuclide inventory will be discussed.
We present the application of a simplified thermal model for the description of the response function of low-temperature calorimeters consisting of
TeO
2
crystals read-out by NTD thermistors operated ...at temperatures
T
∼
10
mK. Relying on both the analysis of the NTD load curves (from which we measured the main thermal conductances of the system) (Biassoni et al. in J Low Temp Phys 206:80–96, 2022) and on the analysis of the shape of thermal pulses acquired at different temperatures, we identified and quantified the physical parameters that determine the characteristic time constants of the pulses. In particular, we identified three different contributions to the heat capacity of the detector: the crystal phonon system (scaling as
T
3
), the NTD electron system (scaling as
T
) and a term related to the metalization process of the NTD electrodes (scaling as
T
-
2
).
TES Microcalorimeters for PTOLEMY Rajteri, M.; Biasotti, M.; Faverzani, M. ...
Journal of low temperature physics,
04/2020, Letnik:
199, Številka:
1-2
Journal Article
Recenzirano
The PTOLEMY project is devoted to directly detect the cosmic neutrino background. A key point for the project success is the development of a device which is capable of detecting electrons with an ...energy resolution lower than 0.05 eV. Microcalorimeters based on transition-edge sensors are among the best candidates since they already reach 0.11 eV of energy resolution for telecomm photons. To further improve the energy resolution, while maintaining a suitable saturation energy, it is necessary to reduce the transition temperature. This could be achieved by proximity effect of a normal-superconducting bilayer. To this aim, TiAu very thin films are under development to demonstrate the feasibility of reaching 0.05 eV energy resolution for light pulses of few eV. Thanks to the high electron stopping power of metals, the penetration depth of low energy incident electrons is limited to few nanometers and, with respect to visible light, we expect a high detection efficiency, while keeping similar dark counts and energy resolution.
Reducing noise to the quantum limit over a large bandwidth is a fundamental requirement for future applications operating at millikelvin temperatures, such as the neutrino mass measurement, the ...next-generation X-ray observatory, the CMB measurement, the dark matter and axion detection, and the rapid high-fidelity readout of superconducting qubits. The read out sensitivity of arrays of microcalorimeter detectors, resonant axion-detectors, and qubits, is currently limited by the noise temperature and bandwidth of the cryogenic amplifiers. The Detector Array Readout with Traveling Wave Amplifiers project has the goal of developing high-performing innovative traveling wave parametric amplifiers with a high gain, a high saturation power, and a quantum-limited or nearly quantum-limited noise. The practical development follows two different promising approaches, one based on the Josephson junctions and the other one based on the kinetic inductance of a high-resistivity superconductor. In this contribution, we present the aims of the project, the adopted design solutions and preliminary results from simulations and measurements.
The HOLMES experiment will perform a precise calorimetric measurement of the end point of the Electron Capture (EC) decay spectrum of 163 Ho in order to extract information on neutrino mass with a ...sensitivity below 2 eV. In its final configuration, HOLMES will deploy 1000 detectors of low temperature microcalorimeters with implanted 163 Ho nuclei. The baseline sensors for HOLMES are Mo/Cu TESs (Transition Edge Sensors) on SiN x membrane with gold absorbers. Considering the large number of pixels and an event rate of about 300 Hz/pixel, a large multiplexing factor and a large bandwidth are needed. To fulfill this requirement, HOLMES will exploit recent advances on microwave multiplexing. In this contribution we present the status of the activities in development, the performances of the developed microwave-multiplexed readout system, and the results obtained with the detectors specifically designed for HOLMES in terms of noise, time and energy resolutions.