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
.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).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 ...Ho. 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 ...Ho 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.
Superconducting Transition Edge Sensors employed in X-ray astrophysics space missions were realized and fully characterized in the Low temperature detector laboratory at UniGe. Several samples of Ir ...and Ir/Au bilayer films were grown by pulsed laser deposition at different deposition rate, varying thickness and resulting variability in critical temperature (
T
c) was observed. In particular, we noticed two classes of films having discrete critical temperature (
T
c), one at about the critical temperature of the bulk Ir and one at around 1.6 times compared to the bulk. Structural characterization was made and interesting correlation between critical temperature (
T
c) and deposition conditions were found. Detailed X-Ray Diffraction investigations suggest a possible explanation of this effect with a clear correlation between microstrain value, grain size, and critical temperatures of the films. The study has been carried out to optimize the specified conditions to grow the film under which it is possible to accurately predict the critical temperature (
T
c) by analyzing the X-ray diffraction patterns of Ir/Au films.
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.
The assessment of neutrino absolute mass scale is still a crucial challenge in today particle physics and cosmology. Beta or electron capture spectrum end-point study is currently the only ...experimental method which can provide a model-independent measurement of the absolute scale of neutrino mass. HOLMES is an experiment funded by the European Research Council to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the electron capture decay of the artificial isotope
163
Ho. In a calorimetric measurement, the energy released in the decay process is entirely contained into the detector, except for the fraction taken away by the neutrino. This approach eliminates both the issues related to the use of an external source and the systematic uncertainties arising from decays on excited final states. The most suitable detectors for this type of measurement are low-temperature thermal detectors, where all the energy released into an absorber is converted into a temperature increase that can be measured by a sensitive thermometer directly coupled with the absorber. This measurement was originally proposed by De Rujula and Lusignoli (Nucl Phys B 219:277,
1983
.
https://doi.org/10.1016/0550-3213(83)90642-9
), but only in the last decade the technological progress in detectors development has allowed to design a sensitive experiment. HOLMES plans to deploy a large array of low-temperature microcalorimeters with implanted
163
Ho nuclei. In this contribution we outline the HOLMES project with its physics reach and technical challenges, along with its status and perspectives.
The TORIO-229 experiment aims for a direct model-independent determination of the transition energy of
229
m
Th produced in
233
U alpha decay. This knowledge will be of interest for the development ...of a scientific clock exploiting the thorium isomeric state, which would be able to significantly surpass the precision of the presently best clocks. As a detector for the isomeric transition, it is planned to use an array of fast transition-edge sensors (TESs) which demonstrated to be feasible in our previous work where the Ir/Au TES prototype demonstrated
4.6
±
1.7
µs rise time,
5.8
±
2.1
µs fall time and
0.789
±
0.023
eV energy resolution and signal-to-noise ratio of
∼
10 with one-photon (2.824 eV) signal, satisfying the experimental requirements. Such a microcalorimeter will allow to register the transition in every possible channel in the energy range from 3 to 50 eV and with a lifetime of > 5 µs. To have a full characterization of a single TES for the final detector array design, its thermal conductance has to be measured. In this contribution, we report on a test measurement of thermal coupling of a TORIO-229 prototype-like iridium-gold TES.
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.
The HOLMES experiment aims to directly measure the
ν
mass studying the
163
Ho electron capture decay spectrum developing arrays of TES-based microcalorimeters implanted with O(300 Bq/detector) Ho ...atoms. The embedding of the source inside detectors is a crucial step of the experiment. Because the
163
Ho production process (neutron irradiation of a
162
Er sample) is not perfectly free from impurities, Ho source must be separated from a lot of contaminants. A chemical processing removes every species other than Ho, but it is not sufficient to remove all isotope-related background sources: Indeed,
166
m
Ho beta decay can produce fake signal in the region of interest. For this reason, a dedicated implantation system was set up. It is designed to achieve the separation power better than 5
σ
at 163/166 a.m.u. allowing an efficient Ho ions implantation inside microcalorimeter absorbers. Its main components are a 50 kV sputter-based ion source, a magnetic dipole and a target chamber. A specially designed co-evaporation system was designed to “grow” the gold microcalorimeter absorber during the implantation process, increasing the maximum achievable activity which can be implanted. The machine performances were evaluated by means of calibration runs using
63
Cu/
65
Cu and Mo beams. A special care was given to the study of the more effective way to populate source plasma with Ho ions obtained from different Ho compounds by sputtering process. In this work, the machine development and commissioning are described.
PDF
