Search

The fractional electron capture probabilities of 59Ni were measured using metallic magnetic calorimeters (MMCs). 59Ni was one of the radionuclides chosen as a part of the European Metrology Research (EMPIR) project MetroMMC. The measurement was performed by using the decay energy spectroscopy (DES) technique, where the radionuclide is embedded in the absorber to have a 4π geometry. Two different source preparation techniques adapted for the measurement are also discussed: electroplating on gold foil and micro-drop-dispensing on gold nanofoam. The total energy spectra obtained from both sources are compared with each other, and the measured fractional electron capture probabilities are compared with those available in the literature and from the BetaShape code. [ABSTRACT FROM AUTHOR]

Recent advances in the development of cryogenic particle detectors such as magnetic microcalorimeters allow the fabrication of sensor arrays with an increasing number of pixels. Since these detectors must be operated at the lowest temperatures, the readout of large detector arrays is still quite challenging. This is especially true for the ECHo experiment, which presently aims to simultaneously run 6,000 two pixel detectors to investigate the electron neutrino mass. For this reason, we developed a readout system based on a microwave SQUID multiplexer (μ MUX) that is operated by a custom software-defined radio (SDR) at room-temperature. The SDR readout electronics consist of three distinct hardware units: a data processing board with a Xilinx ZynqUS+ MPSoC; a converter board that features DACs, ADCs, and a coherent clock distribution network; and a radio frequency front-end board to translate the signals between the baseband and the microwave domains. Here, we describe the characteristics of the full-scale SDR system. First, the generated frequency comb for driving the μ MUX was evaluated. Subsequently, by operating the SDR in direct loopback, the crosstalk of the individual channels after frequency demultiplexing was investigated. Finally, the system was used with a 16-channel μ MUX to evaluate the linearity of the SDR, and the noise contributed to the overall readout setup. [ABSTRACT FROM AUTHOR]

In the last years, the COSINUS (Cryogenic Observatory for SIgnals seen in Next generation Underground Searches) experiment has made significant progress both in the construction of its facility and in pursuing its physics goals: At Laboratori Nazionali del Gran Sasso (LNGS) in Italy, an underground facility was constructed, which will house experimental detectors for dark matter direct detection in a dry dilution cryostat. Construction of the main structures at the COSINUS site is finished, including the control building, the cryostat access level, and the water tank which will serve as a Cherenkov muon veto around the cryostat. With a nuclear recoil threshold of 4 keV, the latest COSINUS detector prototype approaches the design goal of 1 keV, and particle discrimination on event-by-event basis has been demonstrated. This contribution gives a brief overview on the status of COSINUS. [ABSTRACT FROM AUTHOR]

Liquid argon time-projection chambers (LArTPCs) have become a prominent tool for experiments in particle physics. Recent years have yielded significant advances in the techniques used to capture the signals generated by these cryogenic detectors. This article summarizes these novel developments for detection of ionization electrons and scintillation photons in LArTPCs. New methods to capture ionization signals address the challenges of scaling traditional techniques to the large scales necessary for future experiments. Pixelated readouts improve signal fidelity and expand the applicability of LArTPCs to higher-rate environments. Methods that leverage amplification in argon enable measurements in the keV regime and below. Techniques to enhance collection of argon scintillation photons improve calorimetry and expand the physics program for very large detectors. Future efforts aim to demonstrate systems for the combined detection of both electrons and photons. [ABSTRACT FROM AUTHOR]

CUPID is a next-generation bolometric experiment aiming at searching for neutrinoless double-beta decay with ∼250 kg of isotopic mass of 100Mo. It will operate at ∼10 mK in a cryostat currently hosting a similar-scale bolometric array for the CUORE experiment at the Gran Sasso National Laboratory (Italy). CUPID will be based on large-volume scintillating bolometers consisting of 100Mo-enriched Li2MoO4 crystals, facing thin Ge-wafer-based bolometric light detectors. In the CUPID design, the detector structure is novel and needs to be validated. In particular, the CUORE cryostat presents a high level of mechanical vibrations due to the use of pulse tubes and the effect of vibrations on the detector performance must be investigated. In this paper we report the first test of the CUPID-design bolometric light detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse tube in an above-ground lab. Light detectors are characterized in terms of sensitivity, energy resolution, pulse time constants, and noise power spectrum. Despite the challenging noisy environment due to pulse-tube-induced vibrations, we demonstrate that all the four tested light detectors comply with the CUPID goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise. Indeed, we have measured 70-90 eV RMS for the four devices, which show an excellent reproducibility. We have also obtained high energy resolutions at the 356 keV line from a 133Ba source, as good as Ge semiconductor γ detectors in this energy range.

An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers equipped with 16 bolometric Ge light detectors, aiming at optimization of detector structure for CROSS and CUPID double-beta decay experiments, was constructed and tested in a low-background pulse-tube-based cryostat at the Canfranc underground laboratory in Spain. Performance of the scintillating bolometers was studied depending on the size of phonon NTD-Ge sensors glued to both LMO and Ge absorbers, shape of the Ge light detectors (circular vs. square, from two suppliers), in different light collection conditions (with and without reflector, with aluminum coated LMO crystal surface). The scintillating bolometer array was operated over 8 months in the low-background conditions that allowed to probe a very low, μBq/kg, level of the LMO crystals radioactive contamination by 228Th and 226Ra.

The Cryogenic Underground Observatory for Rare Events (CUORE) is the most sensitive experiment searching for neutrinoless double-beta decay (0νββ) in 130Te. CUORE uses a cryogenic array of 988 TeO2 calorimeters operated at ∼10 mK with a total mass of 741 kg. To further increase the sensitivity, the detector response must be well understood. Here, we present a non-linear thermal model for the CUORE experiment on a detector-by-detector basis. We have examined both equilibrium and dynamic electro-thermal models of detectors by numerically fitting non-linear differential equations to the detector data of a subset of CUORE channels which are well characterized and representative of all channels. We demonstrate that the hot-electron effect and electric-field dependence of resistance in NTD-Ge thermistors alone are inadequate to describe our detectors' energy-dependent pulse shapes. We introduce an empirical second-order correction factor in the exponential temperature dependence of the thermistor, which produces excellent agreement with energy-dependent pulse shape data up to 6 MeV. We also present a noise analysis using the fitted thermal parameters and show that the intrinsic thermal noise is negligible compared to the observed noise for our detectors.

Silicon Photomultipliers (SiPMs) have emerged as leading photon detectors in experimental physics since their introduction in the late 1990s. With performance characteristics superior to those of traditional photodetectors, SiPMs exhibit up to 60% photon detection efficiency, rapid signal rise times, and resistance to magnetic fields. Their solid-state construction enables mass production, compactness, and high spatial resolution, facilitating their integration into a wide range of experimental setups. Although susceptible to radiation damage, mitigation strategies are being studied to allow their reliable operation even in environments with elevated radiation levels. SiPMs excel in detecting low levels of light, making them well suited for applications involving scintillation and Cherenkov light. Their ability to operate effectively at cryogenic temperatures allows the construction of a new class of multi-tons rare event search experiments such as Darkside-20k. Insensitivity to the magnetic field and mitigation of the radiation damages are making SiPMs well-suited to be used in accelerator driven physics such as Cherenkov light detectors for Particle IDentification (PID) in the future Electron Ion Collider (EIC). [ABSTRACT FROM AUTHOR]

The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrino-less double-beta (0νββ) decay that has been able to reach the one-ton scale. The detector, located at the Laboratori Nazionali del Gran Sasso in Italy, consists of an array of 988 TeO2 crystals arranged in a compact cylindrical structure of 19 towers. Following the completion of the detector construction in August 2016, CUORE began its first physics data run in 2017 at a base temperature of about 10 mK. Following multiple optimization campaigns in 2018, CUORE is currently in stable operating mode. In 2019, CUORE released its second result of the search for 0νββ corresponding to a TeO2 exposure of 372.5 kgyr and a median exclusion sensitivity to a 130Te 0νββ decay half-life of 1.7 1025 yr. We find no evidence for 0νββ decay and set a 90% C.I. Bayesian lower limit of 3.2 1025 yr on the 130Te 0νββ decay half-life. We present the current status of CUORE's search for 0νββ. We give an update of the CUORE background model and the measurement of the 130Te two neutrino double-beta (2νββ) decay half-life. Eventually, we show the preliminary results on half-life limits from the analysis of 130Te 0νββ and 2νββ decay to the first 0+ excited state of 130Xe.

Cryogenic detectors can detect the smallest energy depositions via the scattering of the incoming particle with the detector material. The deposited energy leads to minimal temperature rises of a few μK , read out via transition edge sensors and SQUIDs. Using scintillating crystals as detector material offers the possibility of discriminating between nuclear recoils from dark matter scattering and electromagnetic background events. The CRESST experiment pioneered this technology and is still among the most sensitive experiments searching for sub-GeV dark matter particles. The technology is now also used by other experiments for dark matter searches (COSINUS) and for measuring coherent elastic neutrino-nucleus scattering (NUCLEUS). We discuss cryogenic detectors' detection principle and their application. We present the latest dark matter results from CRESST, a new type of background, and the status of the COSINUS and NUCLEUS experiments. This article is part of the theme issue 'The particle-gravity frontier'. [ABSTRACT FROM AUTHOR]

We describe a technique to optimize the dynamic performance of microwave SQUID multiplexer (µMUX)-based systems. These systems proved to be adequate for reading out multiple cryogenic detectors simultaneously. However, the requirement for denser detector arrays to increase the sensitivity of scientific experiments makes its design a challenge. When modifying the readout power, there is a trade-off between decreasing the signal-to-noise ratio (SNR) and boosting the nonlinearities of the active devices. The latter is characterized by the spurious free dynamic range (SFDR) parameter and manifests as an increment in the intermodulation products and harmonics power. We estimate the optimal spectral location of the SQUID signal containing the detector information for different channels. Through the technique, what we refer to as Spectral Engineering, it is possible to minimize the SNR degradation while maximizing the SFDR of the detector signal, thus, overcoming the trade-off. [ABSTRACT FROM AUTHOR]

The AnaBHEL experiment aims to detect the analog Hawking radiation emitted by an accelerated relativistic plasma mirror for which the effective event horizon is analogous to that of a black hole, thanks to the equivalence principle. This radiation is composed of a few Hawking photons emitted simultaneously in the infrared band and the 'partner photons' in the ultraviolet band. The former is emitted in the opposite direction of the mirror propagation and is redshifted in the laboratory frame. In the AnaBHEL scheme, high-intensity petawatt laser pulses, will be used to produce the relativistic accelerated plasma mirrors from a helium gas jet. Infrared and ultraviolet photons generated by the mirrors will be detected by dedicated superconducting nanowire single-photon detectors (SNSPDs) at very low temperature and by multichannel plates at room temperature, respectively. Details of the setup design are discussed. [ABSTRACT FROM AUTHOR]

A scintillating bolometer based on a large cubic Li$_{2}$$^{100}$MoO$_4$crystal (45 mm side) and a Ge wafer (scintillation detector) has been operatedin the CROSS cryogenic facility at the Canfranc underground laboratory inSpain. The dual-readout detector is a prototype of the technology that will beused in the next-generation $0\nu2\beta$ experiment CUPID. The measurementswere performed at 18 and 12 mK temperature in a pulse tube dilutionrefrigerator. This setup utilizes the same technology as the CUORE cryostatthat will host CUPID and so represents an accurate estimation of the expectedperformance. The Li$_{2}$$^{100}$MoO$_4$ bolometer shows a high energyresolution of 6 keV FWHM at the 2615 keV $\gamma$ line. The detection ofscintillation light for each event triggered by the Li$_{2}$$^{100}$MoO$_4$bolometer allowed for a full separation ($\sim$8$\sigma$) between$\gamma$($\beta$) and $\alpha$ events above 2 MeV. The Li$_{2}$$^{100}$MoO$_4$crystal also shows a high internal radiopurity with $^{228}$Th and $^{226}$Raactivities of less than 3 and 8 $\mu$Bq/kg, respectively. Taking also intoaccount the advantage of a more compact and massive detector array, which canbe made of cubic-shaped crystals (compared to the cylindrical ones), this testdemonstrates the great potential of cubic Li$_{2}$$^{100}$MoO$_4$ scintillatingbolometers for high-sensitivity searches for the $^{100}$Mo $0\nu2\beta$ decayin CROSS and CUPID projects.

A scintillating bolometer based on a large cubic Li$_{2}$$^{100}$MoO$_4$crystal (45 mm side) and a Ge wafer (scintillation detector) has been operatedin the CROSS cryogenic facility at the Canfranc underground laboratory inSpain. The dual-readout detector is a prototype of the technology that will beused in the next-generation $0u2\beta$ experiment CUPID. The measurementswere performed at 18 and 12 mK temperature in a pulse tube dilutionrefrigerator. This setup utilizes the same technology as the CUORE cryostatthat will host CUPID and so represents an accurate estimation of the expectedperformance. The Li$_{2}$$^{100}$MoO$_4$ bolometer shows a high energyresolution of 6 keV FWHM at the 2615 keV $\gamma$ line. The detection ofscintillation light for each event triggered by the Li$_{2}$$^{100}$MoO$_4$bolometer allowed for a full separation ($\sim$8$\sigma$) between$\gamma$($\beta$) and $\alpha$ events above 2 MeV. The Li$_{2}$$^{100}$MoO$_4$crystal also shows a high internal radiopurity with $^{228}$Th and $^{226}$Raactivities of less than 3 and 8 $\mu$Bq/kg, respectively. Taking also intoaccount the advantage of a more compact and massive detector array, which canbe made of cubic-shaped crystals (compared to the cylindrical ones), this testdemonstrates the great potential of cubic Li$_{2}$$^{100}$MoO$_4$ scintillatingbolometers for high-sensitivity searches for the $^{100}$Mo $0u2\beta$ decayin CROSS and CUPID projects.

A novel system formed by a Microwave Superconducting Quantum Interference Device (SQUID) Multiplexer (μ MUX) and a room temperature electronics employs frequency division multiplexing (FDM) technique to read out multiple cryogenic detectors. Since the detector signal is embedded in the phase of the SQUID signal, a Digital Quadrature Demodulator (DQD) is widely implemented to recover it. However, the DQD also generates a signal that aliases into the first Nyquist zone affecting the demodulated detector signal. In this work, we demonstrate how this spurious signal is generated and a mathematical model of it is derived and validated. In addition, we discuss different proposals to improve the attenuation of this undesired signal. Lastly, we implement one of the proposals in our readout system. Our measurements show an enhancement in the spurious signal attenuation of more than 35 dB. As a result, this work contributes to attenuate the spurious below the system noise. [ABSTRACT FROM AUTHOR]

The EDELWEISS collaboration aims for direct detection of light dark matter using germanium cryogenic detectors with low threshold phonon sensor technologies and efficient charge readout designs. We describe here the development of Ge bolometers equipped with high impedance thermistors based on a NbxSi1−x TES alloy. High aspect ratio spiral designs allow the TES impedance to match with JFET or HEMT front-end amplifiers. We detail the behavior of the superconducting transition properties of these sensors and the detector optimization in terms of sensitivity to a-thermal phonons. We report preliminary results of a 200 g Ge detector that was calibrated using 71Ge activation by neutrons at the LSM underground laboratory. [ABSTRACT FROM AUTHOR]

As noble liquid time projection chambers grow in size their high voltage requirements increase, and detailed, reproducible studies of dielectric breakdown and the onset of electroluminescence are needed to inform their design. The Xenon Breakdown Apparatus (XeBrA) is a 5-liter cryogenic chamber built to characterize the DC high voltage breakdown behavior of liquid xenon and liquid argon. Electrodes with areas up to 33 cm2 were tested while varying the cathode-anode separation from 1 to 6 mm with a voltage difference up to 75 kV. A power-law relationship between breakdown field and electrode area was observed. The breakdown behavior of liquid argon and liquid xenon within the same experimental apparatus was comparable.

Athena (advanced telescope for high-energy astrophysics) is an ESA large-class mission, at present under a re-definition “design-to-cost” phase, planned for a prospective launch at L1 orbit in the second half of the 2030s. It will be an observatory alternatively focusing on two complementary instruments: the X-IFU (X-ray Integral Field Unit), a TES (TransitionEdge Sensor)-based kilo-pixel array which is able to perform simultaneous high-grade energy spectroscopy (~3 eV@7 keV) and imaging over 4′ FoV (field of view), and the WFI (Wide Field Imager), which has good energy spectral resolution (~170 eV@7 keV) and imaging on wide 40′ × 40′ FoV. Athena will be a truly transformational observatory, operating in conjunction with other large observatories across the electromagnetic spectrum available in the 2030s like ALMA, ELT, JWST, SKA, CTA, etc., and in multi-messenger synergies with facilities like LIGO A+, Advanced Virgo+, LISA, IceCube and KM3NeT. The Italian team is involved in both instruments. It has the co-PIship of the cryogenic instrument for which it has to deliver the TES-based Cryogenic AntiCoincidence detector (CryoAC) necessary to guarantee the X-IFU sensitivity, degraded by a primary particle background of both solar and galactic cosmic ray (GCR) origins, and by secondary electrons produced by primaries interacting with the materials surrounding the main detector. The outcome of Geant4 studies shows the necessity for adopting both active and passive techniques to guarantee the residual particle background at 5 × 10−3 cts cm−2 s−1 keV−1 level in 2–10 keV scientific bandwidth. The CryoAC is a four-pixel detector made of Si-suspended absorbers sensed by Ir/Au TESes placed at

We report the demonstration of a low-power pixelated readout system designed for three-dimensional ionization charge detection and digital readout of liquid argon time projection chambers (LArTPCs) . Unambiguous 3D charge readout was achieved using a custom-designed system-on-a-chip ASIC (LArPix) to uniquely instrument each pad in a pixelated array of charge-collection pads. The LArPix ASIC, manufactured in 180 nm bulk CMOS, provides 32 channels of charge-sensitive amplification with self-triggered digitization and multiplexed readout at temperatures from 80 K to 300 K . Using an 832-channel LArPix-based readout system with 3 mm spacing between pads, we demonstrated low-noise (0

Fractional electron capture probability ratios of 125I were measured using metallic magnetic calorimeters (MMCs). Due to the 4π geometry of the source embedded in the absorber, detection efficiency of nearly 99% was observed for K, L, M, and N capture events. The fractional capture probabilities were calculated from peak area ratios. [ABSTRACT FROM AUTHOR]

The Ricochet reactor neutrino observatory is planned to be installed at the Laue Langevin Institute starting mid-2022. Its scientific goal is to perform a low-energy and high precision measurement of the coherent elastic neutrino-nucleus scattering spectrum in order to explore exotic physics scenarios. Ricochet will host two cryogenic detector arrays: the CryoCube (Ge target) and the Q-array (Zn target), operated at 10 mK. The 1 kg Ge CryoCube will consist of 27 Ge crystals instrumented with NTD-Ge thermal sensors and charge collection electrodes for a simultaneous heat and ionization readout to reject the electromagnetic backgrounds (gamma, beta, x-rays). We present the status of its front-end electronics. The first stage of amplification is made of High Electron Mobility Transistors developed by CNRS/C2N laboratory, optimized to achieve ultra-low noise performance at 1 K with a dissipation as low as 15 μ W per channel. Our noise model predicts that 10 eV heat and 20 eV ee RMS baseline resolutions are feasible with a high dynamic range for the deposited energy (up to 10 MeV) thanks to loop amplification schemes. Such resolutions are mandatory to have a high discrimination power between nuclear and electron recoils at the lowest energies. [ABSTRACT FROM AUTHOR]

We present a measurement of the extraction efficiency of quasi-free electrons from the liquid into the gas phase in a two-phase xenon time-projection chamber. The measurements span a range of electric fields from 2.4 to 7.1 kV/cm in the liquid xenon, corresponding to 4.5 to 13.1 kV/cm in the gaseous xenon. Extraction efficiency continues to increase at the highest extraction fields, implying that additional charge signal may be attained in two-phase xenon detectors through careful high-voltage engineering of the gate-anode region.

We calibrate a two-phase xenon detector at 0.27 keV in the charge channel and at 2.8 keV in both the light and charge channels using a 37Ar source that is directly released into the detector. We map the light and charge yields as a function of electric drift field. For the 2.8 keV peak, we calculate the Thomas-Imel box parameter for recombination and determine its dependence on drift field. For the same peak, we achieve an energy resolution, Eσ/Emean, between 9.8% and 10.8% for 0.1 kV/cm to 2 kV/cm electric drift fields.

Particle induced X-ray emission with the use of focused ion beam (µ-PIXE) utilizing a superconducting tunnel junction (STJ) X-ray spectrometer has been developed to realize light element mapping in the soft X-ray region. A five hundred pixels array of STJ detector has been installed in the µ-PIXE beamline at the accelerator facility in the University of Tsukuba. Performance of a single-pixel STJ detector is tested. The K-lines of light elements C to Al have been separately detected in the pulse height spectra with a broad background, which is attributed substrate-hit events caused by scattered protons and high-energy characteristic X-ray lines. The background is rejected by using the anticoincidence technique or rise-time discrimination. [ABSTRACT FROM AUTHOR]

CUORE is a cryogenic detector that will be operated at LNGS to search for neutrinoless double beta decay (0ββ) of 130Te. The detector installation was completed in summer 2016. Before the installation, several cold runs were done to test the cryogenic system performance. In the last cold run the base temperature of 6.3mK was reached in stable condition. CUORE-0, a CUORE prototype, has proven the feasibility of CUORE, demonstrating that the target background of 0.01 counts/keV/kg/y and the energy resolution of 5 keV are within reach.

This paper describes history and technical evolution of portable devices which use energy-dispersive X-ray fluorescence (EDXRF)-analysis to study works of art. The history starts in 1971, when the first transportable equipment was employed to examine the pigments of Raphael’s painting “La Deposizione” during restoration at the “Istituto Centrale del Restauro” in Rome. Then, paintings of all types were analyzed and metals (bronzes, brasses, gold and silver). The evolution of the exciting source is described (from radioisotopes or big size X-ray tubes, to miniaturized, dedicated X-ray tubes) and of X-ray detectors (from proportional gas counters, to N2-cooled Si or Ge-detectors, to Peltier cooled HgI2 and Si-PIN, to Peltier cooled Si-drift). Also, the pulse height analyzers had an important evolution, from a heavy box to a computer card, to very small electronic circuits included in the detector box. The most “modern” portable EDXRF device is currently composed of a small-size X-ray tube, a Si-drift detector, both properly collimated, a portable computer, and dedicated software for the processing of the data. The total weight of such a device is about 2 kg. The last evolution: from analysis of a limited number of points to a complete scanning of the artifact. A mechanics is also required, with a sophisticated software interfacing mechanics to measuring heads. Maps giving the distribution of all analyzed elements in all areas of the painting “La Fornarina” by Raphael could be obtained. Finally, an accurate analysis of the K or L-X rays of the elements present in the paintings allowed to determine the disposition of the pigment in the correct layer. [ABSTRACT FROM AUTHOR]

Temperature sensors fabricated from ultra-low radioactivity materials have been developed for low-background experiments searching for neutrinoless double-beta decay and the interactions of WIMP dark matter. The sensors consist of electrical traces photolithographically-patterned onto substrates of vapor-deposited parylene. They are demonstrated to function as expected, to do so reliably and robustly, and to be highly radio-pure. This work is a proof-of-concept study of a technology that can be applied to broad class of electronic circuits used in low-background experiments.

Integrated quasi-optical cryogenic terahertz receivers contain arrays of detectors, quasi-optical filters, interferometers, and other metamaterials. Matrices of quasi-optical band-pass, low-pass, and high-pass filters, Fabry–Perot grid interferometers, and arrays of half-wave and electrically small antennas with superconductor-insulator-normal metal-insulator-superconductor (SINIS) sub-terahertz wavelength range detectors were fabricated and experimentally studied on the same computational, technological, and experimental platform. For the design of the filters, we used the periodic frequency-selective surfaces (FSS) approach, contrary to detector arrays that can be presented in a model of distributed absorbers. The structures were fabricated using direct electron beam lithography, thermal shadow evaporation, lift-off, alternatively magnetron sputtering, and chemical and plasma etching. The numerical simulation methods of such structures are sufficiently different: for the reactive matrices with low losses, the approximation of an infinite structure with periodic boundary conditions is applicable, and for the arrays of detectors with dissipative elements of absorbers, a complete analysis of the finite structure with hundreds of interacting ports is applicable. The difference is determined by the presence of dissipation in the detector arrays, the phase of the reflected or re-emitted signal turned out to be undefined and the Floquet periodic boundary conditions are correct only for a phased array antenna. The spectral characteristics of the created filters, interferometers, and antenna arrays were measured in the frequency range 50–600 GHz. [ABSTRACT FROM AUTHOR]

The use of High Purity Germanium detectors operated in ionization mode at cryogenic temperatures is investigated as an external background mitigation solution for bolometers used in rare-event search experiments. A simple experimental setup, running a 52-g Li 2 WO 4 bolometer sandwiched in-between two 2-cm thick High Purity Germanium cylindrical detectors in a dry cryostat, shows promising rejection to environmental gammas and atmospheric muons backgrounds. The acquired data are used together with a Monte Carlo simulation of the setup to extract the main contributions to the external backgrounds expected in an above ground experiment, such as e.g. current and future experimental efforts targeting the detection of coherent elastic neutrino-nucleus scattering at reactor facilities. Based on all these results, a 4 π coverage similar veto system achieving a O (10 keV) energy threshold is expected to achieve a ≳ 73% and a ≳ 92% rejection power for gamma-like and muon-like events, respectively. [ABSTRACT FROM AUTHOR]

There is a global trend to increase the light yield of CsI scintillators used in neutrino and dark matter detection by operating undoped crystals at cryogenic temperatures. However, high light yield alone is not sufficient to guarantee a low-energy threshold. The response of undoped crystals to nuclear recoils at cryogenic temperatures is equally important. A liquid nitrogen-based cryostat was developed to measure the nuclear quenching factor of a small undoped CsI crystal using monoenergetic neutron beams at the Triangle Universities Nuclear Laboratory (TUNL). To minimize neutron scattering, high-Z materials were reduced around the crystal. The structure and performance of the cryostat are described in detail. Using this cryostat, a system light yield of 33. 4 ± 2. 0 photoelectrons per keV electron-equivalent (PE/keV ee) was observed at 5.9 keV ee , enabling the measurement of nuclear quenching factors at very low energies. The results of the quenching factor measurement will be reported in a subsequent paper. Non-negligible negative overshoot was observed in the tails of the observed light pulses. The origin of this issue and the correction procedure are described in detail. This information may be useful for others who encounter similar technical challenges. [ABSTRACT FROM AUTHOR]

Liquid Argon (LAr) is one of the most widely used scintillators in particle detection, due to its low cost, high availability and excellent scintillation properties. A large number of experiments in the neutrino sector are based around using LAr in one or more Time Projection Chambers (TPCs), leading to high resolution three-dimensional particle reconstruction. In this paper, we review and summarise a number of these Liquid Argon Time Projection Chamber (LArTPC) experiments, and briefly describe the specific technologies that they currently employ. This includes single phase LAr experiments (ICARUS T600, MicroBooNE, SBND, LArIAT, DUNE-SP, ProtoDUNE-SP, ArgonCube and Vertical Drift) and dual phase LAr experiments (DUNE-DP, WA105, ProtoDUNE-DP and ARIADNE). We also discuss some new avenues of research in the field of LArTPC readout, which show potential for wide-scale use in the near future. [ABSTRACT FROM AUTHOR]

Extended X-ray absorption fine structure (EXAFS) spectroscopy is a powerful technique that gives element-specific information about the structure of molecules. The development of a laboratory EXAFS spectrometer capable of measuring transmission spectra would be a significant advance as the technique is currently only available at synchrotron radiation lightsources. Here, we explore the potential of cryogenic detectors as the energy-resolving component of a laboratory transmission EXAFS instrument. We examine the energy resolution, count rate, and detector stability needed for good EXAFS spectra and compare these to the properties of cryogenic detectors and conventional X-ray optics. We find that superconducting tunnel junction detectors are well-suited for this application. [ABSTRACT FROM AUTHOR]

Searches for dark matter with cryogenic detectors are pushing to lower energy thresholds at each development stage. Consequently, new approaches for detector calibration at the proposed energy scales are necessary. In the case of SuperCDMS SNOLAB, energy thresholds in the range of a few eV are expected. In this paper, we are reporting R&D work for new ideas to calibrate cryogenic detectors in the eV range utilizing LEDs of various wavelengths operated at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

QUBIC is a ground-based experiment aiming to measure the B-mode polarization of the cosmic microwave background. The developed instrument is an innovative two-frequency band bolometric interferometer that will operate at 300 mK with NbSi TES arrays. In this paper, we describe the fabrication process of the detectors. [ABSTRACT FROM AUTHOR]

We present the noise performance of high electron mobility transistors (HEMT) developed by CNRS/C2N laboratory. Various HEMT's gate geometries with 2 pF to 230 pF input capacitance have been studied at 4 K. A model for both voltage and current noises has been developed with frequency dependence up to 1 MHz. These HEMTs exhibit low dissipation, excellent noise performance and can advantageously replace traditional Si-JFETs for the readout of high impedance thermal sensor and semiconductor ionization cryogenic detectors. Our model predicts that cryogenic germanium detectors of 30 g with 10 eV heat and 20 eV ee baseline resolution are feasible if read out by HEMT-based amplifiers. Such resolution allows for high discrimination between nuclear and electron recoils at low threshold. This capability is of major interest for coherent elastic neutrino scattering and low-mass dark matter experiments such as Ricochet and EDELWEISS. [ABSTRACT FROM AUTHOR]

Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) is a long-standing direct dark matter detection experiment with cryogenic detectors located at the underground facility Laboratori Nazionali del Gran Sasso in Italy. CRESST-III, the third generation of CRESST, was specifically designed to have a world-leading sensitivity for low-mass dark matter (DM) (less than 2 GeV/ c 2 ) to probe the spin-independent DM-nucleus cross section. At present, a large part of the parameter space for spin-independent scattering off nuclei remains untested for dark matter particles with masses below few GeV/ c 2 although many motivated theoretical models having been proposed. The CRESST-III experiment employs scintillating CaWO 4 crystals of ∼ 25 g as target material for dark matter interactions operated as cryogenic scintillating calorimeters at ∼ 10 mK. CRESST-III first data taking was successfully completed in 2018, achieving an unprecedented energy threshold for nuclear recoils. This result extended the present sensitivity to DM particles as light as ∼ 160 MeV/ c 2 . In this paper, an overview of the CRESST-III detectors and results will be presented. [ABSTRACT FROM AUTHOR]

We present a strip transition-edge sensor microcalorimeter linear array detector developed for energy dispersive X-ray diffraction imaging and Compton scattering applications. The prototype detector is an array of 20 transition-edge sensors with absorbers in strip geometry arranged in a linear array. We discuss the fabrication steps needed to develop this array including Mo/Cu bilayer, Au electroplating, and proof-of-principle fabrication of long strips of SiN x membranes. We demonstrate minimal unwanted effect of strip geometry on X-ray pulse response and show linear relationship of 1/pulse height and pulse decay times with absorber length. For the absorber lengths studied, our preliminary measurements show energy resolutions of 40–180 eV near 17 keV. Furthermore, we show that the heat flow to the cold bath is nearly independent of the absorber area and depends on the SiN x membrane geometry. [ABSTRACT FROM AUTHOR]

Integrated quasi-optical cryogenic terahertz receivers contain arrays of detectors, quasi-optical filters, interferometers, and other metamaterials. Matrices of quasi-optical band-pass, low-pass, and high-pass filters, Fabry–Perot grid interferometers, and arrays of half-wave and electrically small antennas with superconductor-insulator-normal metal-insulator-superconductor (SINIS) sub-terahertz wavelength range detectors were fabricated and experimentally studied on the same computational, technological, and experimental platform. For the design of the filters, we used the periodic frequency-selective surfaces (FSS) approach, contrary to detector arrays that can be presented in a model of distributed absorbers. The structures were fabricated using direct electron beam lithography, thermal shadow evaporation, lift-off, alternatively magnetron sputtering, and chemical and plasma etching. The numerical simulation methods of such structures are sufficiently different: for the reactive matrices with low losses, the approximation of an infinite structure with periodic boundary conditions is applicable, and for the arrays of detectors with dissipative elements of absorbers, a complete analysis of the finite structure with hundreds of interacting ports is applicable. The difference is determined by the presence of dissipation in the detector arrays, the phase of the reflected or re-emitted signal turned out to be undefined and the Floquet periodic boundary conditions are correct only for a phased array antenna. The spectral characteristics of the created filters, interferometers, and antenna arrays were measured in the frequency range 50–600 GHz.

Solid state detectors and low-temperature calorimeters are widely employed in rare event searches, because of their excellent sensitivity and consequent low energy threshold. A common procedure to establish the energy threshold is to define the trigger level at a fixed number of baseline standard deviations (sigmas) above the baseline level, typically 3 σ or 5 σ. This is not an ideal option when the threshold becomes a critical parameter for the detectors, requiring an optimised definition of the trigger. Recorded events with a small amplitude-to-noise ratio likely survive the selection criteria of the analysis chain contributing to the experiment background. We present a method to quantify the lowest trigger threshold achievable as a function of the acceptable amount of noise events triggered for the physics case under investigation. We then apply this novel method to existing experimental and simulated data to validate the model we presented. [ABSTRACT FROM AUTHOR]

We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, (3) and it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath. We tested this new technique with a 16 cm 2 Ge light detector with thermistor readout sitting on the surface of a large TeO 2 bolometer. The light collection efficiency was increased by greater than 50% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20 eV RMS that, together with increased light collection, enabled us to obtain the best α vs β ∕ γ discrimination ever obtained with massive TeO 2 crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE. [ABSTRACT FROM AUTHOR]