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.
Spectrometers based on the magnetic adiabatic collimation followed by an electrostatic filter (MAC-E-filter) principle combine high angular acceptance with an excellent energy resolution. These ...features make MAC-E-filters very valuable for experiments where the kinetic energy of ions or electrons from rare processes has to be measured with utmost sensitivity and precision. Examples are direct neutrino mass experiments like KATRIN which investigate the energy of electrons in the endpoint region of the tritium
β
-spectrum. However, the MAC-E-filter is a very sharp energy high-pass filter but not a differential spectrometer. To determine a spectral shape of a charged particle source, different electric retarding potentials have to be used sequentially, reducing the statistics. In a previous work we have shown that the advantages of the standard MAC-E-filter can be combined with a measurement of the time-of-flight (TOF), allowing to determine spectral information over a certain energy range with one retarding potential only, with the corresponding gain in statistics. This TOF method requires one to know the start time of the charged particles, which is not always possible. Therefore, we propose a new method which does not require the determination of the start time and which we call “time-focusing time-of-flight” (tfTOF): by applying a time dependent acceleration and deceleration potential at a subsequent MAC-E-filter, an energy dependent post-bunching of the charged particles is achieved.
Ir Film Structural Properties for TES Application Ferrari Barusso, L.; Tugliani, S.; Fedkevych, M. ...
IEEE transactions on applied superconductivity,
08/2023, Letnik:
33, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Iridium films grown by pulsed laser deposition (PLD) show different critical temperatures ( T c ), which can be almost twice the T c of the bulk. This difference is related to the thickness and ...deposition conditions. To understand this effect, we grew different films with different configuration parameters: laser focusing, distance to the Ir target, and deposition time. We then measured the T c and analyzed the film with structural measurements by X-ray diffraction (XRD), looking at a possible correlation with the grain size of the film itself. The work was performed to determine the film growth conditions at which it is possible to obtain predetermination of T c with good accuracy using XRD pattern characteristics of Ir 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 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.
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.
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.
Status of the HOLMES Experiment De Gerone, M.; Alpert, B.; Balata, M. ...
Journal of low temperature physics,
12/2022, Letnik:
209, Številka:
5-6
Journal Article
Recenzirano
Odprti dostop
The assessment of the absolute
ν
mass scale is a crucial challenge in today’s particle physics and cosmology. The only experimental method which can provide a model-independent measurement is the ...investigation of endpoint distortion in beta/electron capture spectra.
163
Ho is a good choice thanks to its low electron capture Q value (about 2.8 keV), the proximity of the end-point to resonance M1 and its half-life (4570 years). The HOLMES experiment will exploit a calorimetric measurement of
163
Ho decay spectrum deploying a large set of cryogenic micro-calorimeters containing implanted
163
Ho. In order to get the best experimental sensitivity, it is crucial to combine high activity with very small undetected pileup contribution. Therefore, the main tasks of the experiment consist of: the development of about 1000 fast (3
μ
s time resolution) cryogenic micro-calorimeters characterized by extraordinary energy resolution (down to few eV); the embedding of
163
Ho source inside the calorimeters, avoiding to spoil detectors’ thermodynamical properties (mainly heat capacity) and preventing pileup issues. Moreover, it is also necessary to avoid contamination from other radionuclides, mainly
166
m
Ho. Finally, an efficient high-bandwidth multiplexed readout has to be developed. The commissioning of the first implanted array is currently ongoing; the first data acquisition is expected to start in fall 2022. Here, the status of the experiment and the first results of detector commissioning will be discussed.
One of the major challenges in nowadays particle physics and astrophysics is the determination of the absolute neutrino mass scale. A powerful tool to evaluate the effective neutrino mass is the ...calorimetric measurement of the energy released in a nuclear decay involving neutrino. In order to reach a sensitivity on the neutrino mass of the order of 1 eV, not only detectors characterized by high performances (i.e. energy and time resolution of <inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula> eV at keV and <inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula>1 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>s, respectively) are needed but also many detectors working in parallel are required. Microwave frequency readout provides an effective technique to read out large arrays of low temperature detectors allowing to reach a multiplex factor of the order of thousands. This technique is the one used to read out the 1000 Transition Edge Sensors of HOLMES, an experiment that aims at measuring the electron neutrino mass by means of the electron capture (EC) decay of <inline-formula><tex-math notation="LaTeX">^{163}</tex-math></inline-formula>Ho with an expected sensitivity of the order of 1 eV. In this contribution we present the characterization of the microwave-multiplexed readout system, and the results obtained with the detectors specifically designed for HOLMES.
The 50 mK cryogenic focal plane anti-coincidence detector of the Athena X-ray observatory (CryoAC) is a silicon suspended absorber sensed by a network of about 400 Ir/Au Transition Edge Sensors (TES) ...and connected through silicon bridges to a surrounding silicon frame plated with gold (rim). The device is shaped by Deep Reactive Ion Etching (DRIE) from a single silicon wafer of 500μm. There are two different possible geometries: a single Monolithic absorber and a Segmented one with 4 distinct absorber structures. As part of the payload of space mission the detector must resist to several mechanical excitation. We have tested a set of structural prototypes of the CryoAC vibrating several hexagonal silicon samples by using the vibrational mask provided by SRON which is responsible for FPA design. The aim is to have a first information on the mechanical response of the silicon bridges that connect the absorber to the rim, to start a trade-off over the two geometries and to validate the elastic-mechanical response.
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