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Sm–Nd chronometers use 146 Sm and 147 Sm to determine the ages of major events in the early Solar System. Their half-lives are the most important nuclear parameters determining the accuracy of chronometry. However, the 146 Sm half-life is not well-established: the published values differ by ∼ 30%, which results in significant uncertainties in the Solar System timeline. We are re-measuring the half-lives of 146 Sm and 147 Sm using decay energy spectroscopy and metallic magnetic calorimeters to improve the accuracy of the Sm–Nd chronometers. We report recent experimental results from our first measurement of a 147 Sm source, as well as status and plans for experiments on 146 Sm. [ABSTRACT FROM AUTHOR]

Pile-up is an unavoidable complication for cryogenic detectors with relatively large heat capacities and slow rise time, such as systems for decay energy spectroscopy employing large Au absorbers. We have simulated the spectral response of such slow cryogenic detectors using Monte-Carlo algorithms to investigate the effects of pile-up on absolute and relative activity measurements. We focus on the impact of non-distinguishable pile-up that occurs when the rising edges of two waveforms originating from different events overlap in time and are interpreted as a single event. This effect can not be readily identified and corrected in experimental data. We investigated two representative cases of absolute decay counting and plutonium isotopic analysis and find that pile-up can distort the reconstruction of both the absolute and relative activities. This Monte-Carlo methodology quantifies of pile-up effects and provides a systematic methodology for calculating corrective factors. [ABSTRACT FROM AUTHOR]

The small dimensions of superconducting tunnel junction (STJ) radiation detectors have motivated the development of STJ arrays to increase detection efficiency and statistical accuracy. We have used a pulsed UV laser and X-rays to characterize and understand non-uniformities in the response of different pixels in Ta-based STJ arrays. To separate the contributions of the detector and the readout electronics, we have also injected the pulses from an arbitrary waveform generator into the array's amplifier chain. We discuss the magnitude and the sources of the non-uniformity and approaches to reduce it. [ABSTRACT FROM AUTHOR]

Metallic magnetic calorimeters (MMCs) are particle detectors that combine ultra-high energy resolution with a predictable and smooth response based on the physics of paramagnetism. For best energy resolution, MMCs are read out with dc SQUID preamplifiers. Since the ac Josephson effect also makes dc SQUIDs broadband RF sources in the 1–100 GHz range, the SQUID can potentially excite RF modes of the MMC sensor, with negative consequences. The importance of this possibility is magnified in direct-coupled MMCs, where the MMC sensor is part of the SQUID loop to maximize performance. For these reasons, the RF behavior of MMC sensors must be investigated. In this report, we present the results of exploratory RF simulations of MMC sensor modes and damping, and we assess three approaches to damp the parallel-meander direct-coupled MMC without excessive noise increase. [ABSTRACT FROM AUTHOR]

We report a new measurement of the 60 keV transition from 241Am. It uses a metallic magnetic calorimeter gamma-ray detector calibrated in the region around 60 keV by four accurately known X-rays and gamma rays from the decay of 169Yb. We determine an energy of 59,539.3 ± 0.3 (stat) ± 0.3 (syst) eV, which is 1.6 ± 0.4 eV lower than the current literature value of 59,540.9 ± 0.1 eV. We discuss the sources of this uncertainty and approaches to address them. [ABSTRACT FROM AUTHOR]

Metallic magnetic calorimeters (MMCs) combine the excellent energy resolution of cryogenic gamma ray detectors with a very small nonlinearity and a reproducible response, owing to their magnetization-based sensor and their metallic heat flow path. These attributes make MMCs well suited for photon and particle spectroscopy applications requiring the highest accuracy. We are developing high-resolution MMC gamma ray detectors with the goal of improving the quality of key nuclear decay data for nuclear safeguards and fundamental science. Our exploratory "integrated" (SQUIDs and sensors on the same chip) 14-pixel MMC designs recently demonstrated energy resolution of 37.5 eV at 60 keV. Here, we describe the design and optimization for a new generation of MMC detectors using both "integrated" and "split" designs (SQUIDs and sensors on separate chips). The new designs are expected to have an energy resolution < 25 eV (< 5 eV) for MMCs optimized for energies up to 100 keV (10 keV) and have up to 32 pixels. [ABSTRACT FROM AUTHOR]

Precise nuclear data from radioactive decays are important for the accurate non-destructive assay of fissile materials in nuclear safeguards. We are developing high energy resolution gamma detectors based on metallic magnetic calorimeters (MMCs) to accurately measure gamma-ray energies and branching ratios of uranium isotopes. Our MMC gamma detectors exhibit good linearity, reproducibility and a consistent response function for low energy gamma-rays. We illustrate the capabilities of MMCs to improve literature values of nuclear data with an analysis of gamma spectra of U-233. In this context, we also improve the value of the energy for the single gamma-ray of the U-233 daughter Ra-225 by over an order of magnitude from 40.09 ± 0.05 to 40.0932 ± 0.0007 keV. [ABSTRACT FROM AUTHOR]

The Advanced Mo-based Rare process Experiment utilizes a cryogen-free dilution refrigerator to operate its low-temperature detectors. Mechanical vibration originating from its pulse tube refrigerator can affect the detector performance. A mechanical filter system has been installed between the 4K and still plates with eddy current dampers in addition to a spring-loaded damping system previously installed below the mixing chamber plate of the cryostat. The filters significantly mitigated vibrations and improved the detector signals. [ABSTRACT FROM AUTHOR]

We present a systematic trigger study for the Advanced Molybdenum-based Rare process Experiment (AMoRE), an international project searching for the neutrinoless double beta decay (0νββ) of 100Mo. AMoRE utilizes a heat and light detection method at millikelvin temperatures. A detector module of AMoRE is composed of a large crystal absorber and metallic magnetic calorimeter temperature sensors. We applied a software filter with various conditions to the continuously saved data from the current AMoRE setup. With a trigger level set to 5 times the standard deviation of the noise signals resulting from a Butterworth filter, an energy threshold, defined as the energy of the signals leading to a 50% trigger efficiency, was found to be 2.2 keV. [ABSTRACT FROM AUTHOR]

The goal of the Advanced Mo-based Rare process Experiment (AMoRE) is to search for the neutrinoless double beta decay of 100Mo using low-temperature detectors consisting of Mo-based scintillating crystals read out via metallic magnetic calorimeters. Heat and light signals are measured simultaneously at millikelvin temperatures, which are reached using a cryogen-free dilution refrigerator. The AMoRE-Pilot experiment, using six 100Mo-enriched, 48Ca-depleted calcium molybdate crystals with a total mass of about 1.9 kg, has been running in the 700-m-deep Yangyang underground laboratory as the pilot phase of the AMoRE project. Several setup improvements through different runs allowed us to achieve a high energy resolution and an efficient particle discrimination. This article briefly presents the status of the AMoRE-Pilot experiment, as well as the plans for the next, larger-scale, experimental stages. [ABSTRACT FROM AUTHOR]

Metallic magnetic microcalorimeters (MMCs) achieve energy resolution comparable to transition-edge sensors (TESs) but rely on different measurement physics that may allow MMCs to surpass TESs in some future applications. We have recently completed fabrication of new MMC γ-ray detector arrays using several exploratory sensor designs. All designs integrate the SQUID and sensor on the same chip and use a superconducting cap layer on the paramagnet, but explore different combinations of combined/separate sensing and magnetization coils and direct/flux transformer coupling to the input SQUIDs. This report describes the design and initial testing of one of these devices, which has so far demonstrated an energy resolution of 38 eV at 60 keV near 10 mK using natural-abundance silver-erbium paramagnet. [ABSTRACT FROM AUTHOR]

We report a very rare case of isolated multiple pulmonary arterial calcification with severe bilateral peripheral pulmonary arterial stenosis diagnosed in utero. Despite treatment with bisphosphonate for 6 months, systolic right ventricular pressure increased persistently and surpassed left ventricular pressure. After successful bilateral pulmonary arterioplasty at 13 months of age, the patient showed decreased systolic right ventricular pressure with normal interventricular septal configuration. This is the first case report for an isolated pulmonary artery calcification without other arterial calcification proven by non-contrast computed tomography of a living patient. [ABSTRACT FROM AUTHOR]

The BeEST experiment is a precision laboratory search for physics beyond the standard model that measures the electron capture decay of 7\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^7$$\end{document}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. [ABSTRACT FROM AUTHOR]