Journal of Low Temperature Physics最新文献

Neutrinoless double-beta decay (0(nu beta beta)) experiments constitute a pivotal probe for elucidating the characteristics of neutrinos and further discovering new physics. Compared to the neutron transmutation-doped germanium thermistors used in 0(nu beta beta) experiments such as CUORE, transition edge sensors (TESs) theoretically have a relatively faster response time and higher energy resolution. These make TES detectors good choice for next generation 0(nu beta beta) experiments. In this paper, AlMn alloy superconducting films, the main components of TES, were prepared and studied. The relationship between critical temperature ((T_{text{c}})) and annealing temperature was established, and the impact of magnetic field on (T_{text{c}}) was tested. The experimental results demonstrate that the (T_{text{c}}) of AlMn film can be tuned in the required range of 10–20 mK by using the above methods, which is a key step for the application of AlMn TES in 0(nu beta beta) experiment. In the test range, the (T_{text{c}}) of AlMn film is sensitive to out-of-plane magnetic field but not to the in-plane magnetic field. Furthermore, we find that a higher annealing temperature results in a more uniform distribution of Mn ions in depth, which opens a new avenue for elucidating the underlying mechanism for tuning (T_{text{c}}).

Sorption coolers show strong potential for ground-based physical experiments and space exploration in the sub-Kelvin temperature regime, with their performance critically dependent on the adsorption behavior of helium on selected adsorbents. While most previous studies have focused on activated carbon, the present work systematically investigates the helium adsorption behavior of three porous materials: metal–organic framework (MOF) HKUST-1, single-walled carbon nanotubes (SWCNT), and multilayer graphene (MLG), over a temperature range of 4 to 77 K and a pressure range of 1 to 500 kPa. Evaluation of several adsorption isotherm models indicates that the Brunauer–Emmett–Teller (BET) model most accurately captures adsorption characteristics of three materials. Experimental results reveal a pronounced temperature dependence. In the low-temperature domain (4 to 10 K), adsorption capacity increases sharply with pressure; however, in the higher-temperature domain (20 K and above), adsorption tends toward saturation. Moreover, the relative adsorption performance of the three materials varies significantly with both temperature and pressure. Under low-temperature, low-pressure conditions (1 kPa, 4 K), SWCNT exhibit the highest adsorption capacity (24.03 mmol g^-1), making them particularly well suited for low-pressure refrigeration applications. In contrast, MLG shows the most significant enhancement in adsorption at high pressures: at 6 K, its isotherm exhibits a pronounced increase with pressure, indicating strong affinity for helium under high-pressure conditions. HKUST-1, by comparison, exhibits a lower overall adsorption capacity, likely due to limitations associated with its framework stability and pore occupancy behavior. These findings provide an experimental basis and theoretical support for the selection and optimization of adsorbents in low-temperature adsorption refrigeration systems.

The magnetization process of the (S=2) antiferromagnetic chain with two competing anisotropies is investigated using the numerical diagonalization of finite-size clusters and some size scaling analyses. As a result, it is found that the system possibly exhibits the translational symmetry broken magnetization plateaus at 1/4 and 3/4 of the saturation magnetization, as well as at 1/2. The phase diagrams for the anisotropies at 1/4, 3/4 and 1/2 magnetizations are presented. In addition, the magnetization curves for several typical anisotropy parameters are obtained.

The flow measurement of cryogenic fluids is frequently complicated by physical phenomena such as phase transition and cavitation, which can significantly impair measurement accuracy and system stability. Multi-stage perforated plate flowmeters have attracted increasing attention due to their potential for accurate flow measurement. However, most existing studies have focused on performance under non-cryogenic conditions, while the unique flow behavior exhibited by cryogenic fluids is often overlooked. In this study, a numerical approach is employed to investigate the flow characteristics of cryogenic fluids through double-stage perforated plate structures. A systematic evaluation is conducted to assess the influence of various operating conditions and structural features on physical flow properties, key dimensionless measurement parameter configurations, and cavitation-induced thermal effects, including the pressure loss coefficient, discharge coefficient, and temperature drop coefficient. The results indicate that when the spacing between plates exceeds a certain threshold, the variations in these parameters tend to stabilize. Furthermore, a novel asymmetric double-stage perforated plate design is proposed. Compared to the symmetric structure, the pressure loss coefficient and discharge coefficient improved by 26.9% and 29.6%, respectively, while the temperature drop coefficient decreased by approximately 30.6%. This suggests that the asymmetric structure can enhance flow measurement accuracy and stability by trading off energy loss. These findings can reveal the underlying mechanisms by which plate geometry influences flow characteristics and measurement accuracy, thereby offering valuable theoretical guidance for the high-precision measurement of cryogenic fluids.

AlMn alloy films are widely fabricated into superconducting transition edge sensors (TESs) for the detection of cosmic microwave background radiation. However, the application in X-ray or gamma-ray detection based on AlMn TES is rarely reported. In this study, X-ray TES detectors based on unique annular AlMn films are developed. The fabrication processes of TES detectors are introduced in detail. The characteristics of three TES samples are evaluated in a dilution refrigerator. The results demonstrate that the I-V characteristics of the three annular TES detectors are highly consistent. The TES detector with the smallest absorber achieved the best energy resolution of 11.0 eV @ 5.9 keV, which is inferior to the theoretical value. The discrepancy is mainly attributed to the larger readout electronics noise than expected.

Percent-level calibration of cryogenic macro-calorimeters with energy thresholds below 100 eV is crucial for light Dark Matter (DM) searches and reactor neutrino studies based on coherent elastic neutrino-nucleus scattering (CEvNS). This paper presents a novel calibration source based on X-ray fluorescence (XRF) of light elements. It uses a (^{55})Fe source to irradiate a two-staged target arrangement, emitting characteristic emission lines from 677 eV to 6.5 keV. We demonstrate the potential of this new XRF source to calibrate a 0.75 g CaWO(_4) crystal of the NUCLEUS and CRAB experiments. Additionally, we introduce CryoLab, an advanced analysis tool for cryogenic detector data, featuring robust methods for data processing, calibration, and high-level analysis, implemented in MATLAB and HDF5. We also present a phenomenological model for energy resolution, which incorporates statistical contributions, systematic effects, and baseline noise, enabling a novel approach to evaluating athermal phonon collection efficiency in macro-calorimeters based on transition edge sensors (TES).

A simple nonrelativistic model is proposed using a non-Abelian magnetic quantization approach. In this model, a deformed of the Heisenberg algebra is used. In the model, the commutator of momenta is considered proportional to the pseudo-spin. Due to the use of non-commutative algebra, a linear term in the momentum is appeared. By this model, the low-energy excitations of graphene are determined. The Landau problem is solved under a uniform magnetic field perpendicular to the plane. Then, the partition function is calculated for two branches: positive and negative. Finally, the thermal and magnetic properties of graphene are calculated. The results show that the magnetic susceptibility has a transition from paramagnetic to diamagnetic in each branch. The transition point depends on the temperature and magnetic field.

We have designed and constructed a magnet surrounding a cylindrical volume of superfluid helium-3 to isolate a region of metastable, supercooled A phase, entirely surrounded by bulk A phase - isolating the ‘bubble’ from rough surfaces that can trigger the transition to the stable B phase. We outline the design of the experimental cell and magnet and show that the performance of the magnet is consistent with simulations, including the capability to produce the high field gradient required for generating a bubble. Future plans include the investigation of possible intrinsic mechanisms underpinning the A-B transition, with potential implications for early-universe cosmological phase transitions.

The optical transition-edge sensor (TES) pushes the boundary on fault-tolerant photonic quantum computers and low-invasive bio-imaging systems. As these systems evolve, there is an increasing demand for using a TES array comprising many sensors, often exceeding one hundred. Critical temperature (T_c) of the TESes should be uniform to ensure that all TESes operate at the same bias point with a series-bias current. Using an ion-milling process, we fabricate new titanium-based TES arrays consisting of 40 TESes. Each TES has lateral dimensions of 15 µm (times ) 13 µm. Our microwave-multiplexing measurement with rf-SQUIDs confirms that 24 out of the 40 TESes exhibit (T_textrm{c} = (336 pm 6),textrm{mK}) uniform enough to apply the common bias. The yield is still 60%; however, this is the first report on the (T_textrm{c}) uniformity of the ion-milling-based TESes. Seven optical fibers are connected to TESes. Five out of the seven sensors show transition. They show energy resolution (0.54 le {Delta }E,(textrm{eV}) le 0.62) without FRM. The best energy resolution achieved without flux ramp modulation is 0.54 eV for a signal at 0.80 eV.

Templated porous materials like MCM-41 offer a scalable platform for studying one-dimensional quantum fluids due to their uniform structure. However, achieving true 1D helium behavior is limited by pore sizes typically larger than helium’s coherence length. Building on prior work using Ar preplating to reduce pore size and soften adsorption potentials, we propose a novel approach: preplating MCM-41 with cesium (Cs). Cs’s large atomic radius and non-wetting interaction with helium create an ideal confinement environment. Preliminary adsorption isotherms and small-angle X-ray scattering data confirm reduced pore radii, supporting the potential for realizing 1D ⁴He quantum fluids in Cs-preplated MCM-41.