Journal of Low Temperature Physics最新文献

We synthesized an Ag:Er alloy having paramagnetic properties to be used as a temperature sensor in metallic magnetic calorimeters. The Ag:Er master alloy and a 2-inch target for film deposition were, respectively, manufactured using vacuum arc melting and RF heating under process conditions designed to minimize impurity contamination. Calculations and measurements of magnetization versus magnetic field were employed to check for magnetic impurities in the host material, Ag, and to estimate the Er concentration in the Ag:Er alloy at each step of the synthesis. The temperature-dependent magnetization of deposited thin films from the synthesized Ag:Er with (^{168})Er isotope was measured in the mK range, demonstrating their suitability as temperature sensors for low-temperature detectors such as metallic magnetic calorimeters.

Any experiment aiming to measure rare events, like Coherent Elastic neutrino-Nucleus Scattering (CE(upnu)NS) or hypothetical Dark Matter scattering, via nuclear recoils in cryogenic detectors relies crucially on a precise detector calibration at sub-keV energies. The Crab collaboration developed a new calibration technique based on the capture of thermal neutrons inside the target crystal. Together with the Nucleus experiment, first measurements with a moderated (^{252})Cf neutron source and a cryogenic ({{textrm{CaWO}}_4}) detector were taken. We observed for the first time the 112eV peak caused by the (^{182})W(n, ({upgamma }))(^{183})W capture reaction and subsequent nuclear recoils. Currently, Crab is preparing a precision measurement campaign based on a monochromatic flux of thermal neutrons from the 250-kW Triga-mark II nuclear reactor at TU Wien. In this contribution, we introduce the Crab technique, present the first measurement of the 112eV peak, report the preparations for the precision measurement campaign, and give an outlook on the impact on the field of cryogenic detectors.

This paper presents a comparative study of various light detectors (LDs) developed for different phases of the AMoRE neutrinoless double beta decay experiment. We analyze the performance of these detectors in terms of characteristics such as time response, light collection, and energy resolution. Our primary focus is on evaluating the performance of the AMoRE-II light detector, which is integral to the forthcoming AMoRE-II experiment. It is found that AMoRE-II type LDs outperform other previous light detector types. The best-performing LD exhibits FWHM energy resolution of 99, 198, 198, and 481 eV for baseline and ⁵⁵Fe X-ray energies of 5.9, 6.5, and 17.5 keV molybdenum X-ray, respectively. We adopted a convolution method to estimate the energy of the scintillation signals from 2.615 MeV gamma rays fully absorbed in a lithium molybdate crystal. The measured energy of scintillation light with AMoRE-II type LDs falls in the range of 2.1–2.5 keV, which corresponds to 0.80–0.96 keV/MeV. This measured energy is approximately 14–39(%) higher than that measured with previous LD types for the experiments.

The AMoRE collaboration conducts experiments to search for the neutrinoless double beta decay of (^{100})Mo using massive (hbox {Li}_{2}hbox {MoO}_{4}) (LMO) crystals in a cryogenic calorimetric detection with metallic magnetic calorimeters (MMCs). The detector module incorporates a light detector with Si or Ge wafers, enabling the simultaneous detection of scintillation light. The forthcoming phase (AMoRE-II) of the experiment will include 6 cm (diameter) (times) 6 cm (height) LMO cylindrical crystals, and this has been chosen to reduce the number of crystals and sensors. Additionally, these crystals will have diffusive surfaces rather than polished ones, which helps to reduce the crystal preparation time. The phonon signal of crystals with diffusive surfaces is slower than that of polished crystals. However, due to the mitigated position dependence, diffusive crystals exhibit better discrimination between (alpha) and (beta)/(gamma) signals by pulse shape analysis. We also found that muon events show two bands in the rise time of the large LMO crystal with polished surface, indicating the muon passage at the edge of the crystal, and the band structure is significantly mitigated in the crystals with the diffusive surfaces. To study the position dependence in the crystal absorber further, we irradiated some R&D detectors with localized (alpha) sources. This paper discusses the particle identification and position dependence of (gamma), (alpha), and muon events for the large AMoRE-II type detectors based on the pulse shape analysis.

The Simons Observatory (SO) is a cosmic microwave background (CMB) experiment located in the Atacama Desert in Chile that will make precise temperature and polarization measurements over six spectral bands ranging from 27 to 285 GHz. Three small aperture telescopes (SATs) and one large aperture telescope (LAT) will house (sim)60,000 detectors and cover angular scales between one arcminute and tens of degrees. We present the performance of the dichroic, low-frequency (LF) lenslet-coupled sinuous antenna transition-edge sensor (TES) bolometer arrays with bands centered at 27 and 39 GHz. The LF focal plane will primarily characterize Galactic synchrotron emission as a critical part of foreground subtraction from CMB data. We will discuss the design, optimization, and current testing status of these pixels.

We describe a pathfinder experiment named DEEPDISH (dark matter extended energy probe: dielectric infrared superconducting haloscope) to search unexplored regions of dark matter (DM) parameter space: first for dark photon DM and later for axion DM with the application of a magnetic field. The DM would convert to photons within an optical stack and subsequently be detected by a microwave kinetic inductance detector (MKID) array.

Achieving high spectral and spatial resolution of wide astrophysical objects in the X-ray band will be the main focus of the future X-ray space telescopes. We explore a new technological solution based on high impedance NbSi TES detectors ((sim )2 M(Omega )) enabling the transfer of the pre-amplification stage to higher temperatures (4 K) and the use of a 50 mK CMOS time-division multiplexer to reduce power dissipation at 50 mK. We present the design and first tests, down to 200 mK, of this CMOS ASIC eventually able to work down to 50 mK and multiplexing 16 high impedance NbSi TES detectors to one 4 K amplifier with a total power budget under 2 (mu )W. In parallel of this development we fabricated 4-by-4 NbSi pixel matrices to build a complete demonstrator (comprising the detector array, presented in another paper to be published, the multiplexing ASIC and the 4 K amplification stage). We aim at a multiplexing frame time of 48 (mu )s leaving 3 (mu )s for reading-out each high impedance pixel. The multiplexing ASIC embeds parasitic capacity compensation techniques.

The BeEST experiment is a precision laboratory search for physics beyond the standard model that measures the electron capture decay of (^7)Be implanted into superconducting tunnel junction (STJ) detectors. For Phase-III of the experiment, we constructed a continuously sampling data acquisition system to extract pulse shape and timing information from 16 STJ pixels offline. Four additional pixels are read out with a fast list-mode digitizer, and one with a nuclear MCA already used in the earlier limit-setting phases of the experiment. We present the performance of the data acquisition system and discuss the relative advantages of the different digitizers.

The LUCE (LUtetium sCintillation Experiment) project will search for the (^{176})Lu electron capture based on a milli-Kelvin calorimetric approach. This decay is of special interest in the fields of nuclear structure, rare event searches, and measurements of nuclear matrix elements of long-lived isotopes. The experiment is primarily searching for a mono-energetic peak from the (7^- rightarrow 2^+) forbidden transition. The current status and design of a novel cryogenic module for the measurements of the electron capture in (^{176})Lu are reported on. Details of future measurement plans are presented.

We describe a testbed to characterize the optical response of compact superconducting on-chip spectrometers in development for the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) mission. EXCLAIM is a balloon-borne far-infrared experiment to probe the CO and CII emission lines in galaxies from redshift 3.5 to the present. The spectrometer, called µ-Spec, comprises a diffraction grating on a silicon chip coupled to kinetic inductance detectors (KIDs) read out via a single microwave feedline. We use a prototype spectrometer for EXCLAIM to demonstrate our ability to characterize the spectrometer’s spectral response using a photomixer source. We utilize an on-chip reference detector to remove the spectral structure introduced by the off-chip optics and a silicon etalon to calibrate the absolute frequency.