We present cosmic muon flux measurements collected across two geomagnetically distinct environments using a novel concentric double-layer plastic scintillator telescope. The detector employs a nested geometry in which a cylindrical inner volume is coaxially enclosed within a cup-shaped outer scintillator, enabling active background rejection and wide-angle acceptance within a portable package. The scintillators were synthesized in-house from a custom epoxy-resin matrix. The system was deployed during the 10th Turkish Antarctic Expedition (TAE-X), with measurements taken at a mid-latitude baseline in Istanbul and at Horseshoe Island, Antarctica. The Antarctic flux exceeded the Istanbul baseline by approximately 41%, consistent with the reduced geomagnetic cutoff rigidity at polar latitudes. A Forbush decrease was also observed in Istanbul, coinciding with a Kp ∼ 8 geomagnetic storm driven by a coronal mass ejection and corroborated by simultaneous neutron monitor data. These results demonstrate the detector’s suitability for continuous cosmic ray monitoring across diverse geomagnetic environments.
The Penning effect plays a crucial role in gas detectors by significantly enhancing ionization efficiency through optimized gas mixtures. Although this effect has been extensively studied in conventional detector configurations, its systematic characterization in Thick Gas Electron Multipliers (THGEMs) remains limited. In this work, we performed concentration-scan measurements on six Penning mixtures based on Ar and Kr (Ar/CO2, Ar/Xe, Ar/DME, Kr/DME, Kr/C3H6, and Kr/iC4H8) using a single-THGEM detector at pressures of 0.6 and 1.0 bar. The effective gain and energy resolution were systematically investigated as functions of the admixture gas concentration. The results show that, with the exception of Ar/CO2, all five remaining mixtures exhibit significant Penning effects. From the analysis of the gain curves, the admixture concentrations corresponding to the minimum THGEM operating voltage were determined for each gas mixture, ranging from 0.1% to 2%. Among them, the optimal concentration of C3H6 in the Kr/C3H6 mixture is about 0.3%, consistent with previous measurements. The degree of gain enhancement due to Penning ionization in these mixtures depends specifically on the energy matching between the first ionization energy of the admixture gas and the excitation energy levels of the noble gas molecules. Based on the monitoring of discharge frequencies near the optimal concentrations for each mixture, the effective gains achievable at the same discharge probability can be quantitatively compared. Compared with pure Ar, the effective gain of Ar/Xe is enhanced by more than a factor of 20 at the same discharge probability, while Kr/DME shows an enhancement of about a factor of 40 compared with pure Kr.
Coherent elastic neutrino-nucleus scattering (CEνNS) represents a powerful probe for low-energy neutrino physics. In this work, we present a novel cryogenic detection scheme utilizing pure CsI crystals coupled with silicon photomultiplier (SiPM) readout. While previous experiments have demonstrated the viability of this detector architecture at liquid-nitrogen temperatures (77 K), theoretical models anticipate significant performance enhancements at deeper cryogenic temperatures. To systematically investigate this regime, we developed a custom-built cryogenic facility with continuous temperature regulation from 30 K to 293 K. Building upon prior single-photon calibrations of the SiPMs at 40 K, we characterized the pure CsI detection system using 13.9–59.54 keV X/γ-rays and 5.5 MeV α-particles. Crucially, we report the observation of a pronounced anti-quenching phenomenon. At 35 K, the scintillation light yield for densely ionizing α-particles reaches 19.2 p.e./keV, unambiguously exceeding the 17.3 p.e./keV measured for electron recoils induced by γ-rays. Because the ionization density profiles of α-particles closely emulate those of low-energy nuclear recoils generated via CEνNS, this enhanced light yield for high linear energy transfer (LET) interactions is of paramount importance for validating the reliability of this technique. This cryogenic pure CsI platform offers a transformative pathway for achieving the ultra-low thresholds required in next-generation reactor CEνNS experiments.
Doppler broadening positron annihilation spectroscopy is a powerful technique for investigation of neutral and negatively-charged atomic-scale defects in materials. However, it has one important drawback, which is that studies are typically designed to only illuminate relative differences in positron annihilation characteristics in a specific suite of samples. It is difficult and considered ill-advised to compare the data that different laboratories report for apparently similar samples, which limits the scope of applications of the technique. The root of the problem is that the resolution and calibration of the detector used to collect the energy spectra of the positron-electron annihilation radiation affect their shape and the S and W parameters that are used for its characterisation. The present study explores whether this obstacle can be overcome by modelling the differences between the data sets that were obtained via different detectors or the same detector at different times. We were able to reproduce the observed differences between the analyses of UO2 that were acquired in our laboratory over the past ∼25 years using the same detector that has changed its properties. However, our attempt to reproduce the differences between our and literature data did not work out as well, which can be pinned in part to a real difference between the samples and in part to the incompleteness of the published descriptions of the methodology. We conclude with recommendations to improve current practices of data acquisition and reporting.
