A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements to text, and revised reference

Aspect-Controlled Neural Argument Generation

We rely on arguments in our daily lives to deliver our opinions and base them on evidence, making them more convincing in turn. However, finding and formulating arguments can be challenging. In this work, we train a language model for argument generation that can be controlled on a fine-grained level to generate sentence-level arguments for a given topic, stance, and aspect. We define argument aspect detection as a necessary method to allow this fine-granular control and crowdsource a dataset with 5,032 arguments annotated with aspects. Our evaluation shows that our generation model is able to generate high-quality, aspect-specific arguments. Moreover, these arguments can be used to improve the performance of stance detection models via data augmentation and to generate counter-arguments. We publish all datasets and code to fine-tune the language model

Operator related attenuation effects in radiometric surveys

Radiometric surveys using airborne, vehicular mounted or backpack detector systems are increasingly used to identify and evaluate complex distributions of radioactivity in the environment. The signals detected depend on the energy and spatial distribution of radioactive sources, the material properties of the environment and the specific properties of the detector systems employed. Materials in close vicinity to the detector such as housings, and intermediate materials may have a critical impact on detection efficiency, and must therefore be taken into account in calibration. This study evaluates the effect of shielding by the body of the operator in backpack surveys. Controlled experiments using point sources and absorbers, chosen to represent the form and composition of human tissue, were conducted, and coupled to an analytical radiation transport model to estimate attenuation factors for mapping of 137Cs. In this way generic factors to correct for this effect using portable spectrometers have been determined. The results compare well with observations at sampled calibration sites in Fukushima and the Solway area in Scotland. Reductions of the 137Cs full-energy peak intensity between 20% and 30% may be expected depending on operator stature and the offset position of backpack systems. Similar effects may be present for other radiometric systems carried by a human operator

The DAMA/LIBRA apparatus

The $\simeq$ 250 kg highly radiopure NaI(Tl) DAMA/LIBRA apparatus, running at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N., is described.Comment: 37 pages, 27 figure

Sound and light from fractures in scintillators

Prompted by intriguing events observed in certain particle-physics searches for rare events, we study light and acoustic emission simultaneously in some inorganic scintillators subject to mechanical stress. We observe mechanoluminescence in ${Bi}_4{Ge}_{3}{O}_{12}$, ${CdWO}_{4}$ and ${ZnWO}_{4}$, in various mechanical configurations at room temperature and ambient pressure. We analyze how the light emission is correlated to acoustic emission during fracture. For ${Bi}_4{Ge}_{3}{O}_{12}$, we set a lower bound on the energy of the emitted light, and deduce that the fraction of elastic energy converted to light is at least $3 \times 10^{-5}$

Radiopurity of Micromegas readout planes

Micromesh Gas Amplification Structures (Micromegas) are being used in an increasing number of Particle Physics applications since their conception fourteen years ago. More recently, they are being used or considered as readout of Time Projection Chambers (TPCs) in the field of Rare Event searches (dealing with dark matter, axions or double beta decay). In these experiments, the radiopurity of the detector components and surrounding materials is measured and finely controlled in order to keep the experimental background as low as possible. In the present paper, the first measurement of the radiopurity of Micromegas planes obtained by high purity germanium spectrometry in the low background facilities of the Canfranc Underground Laboratory (LSC) is presented. The obtained results prove that Micromegas readouts of the microbulk type are currently manufactured with radiopurity levels below 30 microBq/cm2 for Th and U chains and ~60 microBq/cm2 for 40K, already comparable to the cleanest detector components of the most stringent low background experiments at present. Taking into account that the studied readouts were manufactured without any specific control of the radiopurity, it should be possible to improve these levels after dedicated development.Comment: 15 pages, 2 figure

Spatially uniform calibration of a liquid xenon detector at low energies using 83m-Kr

A difficult task with many particle detectors focusing on interactions below ~100 keV is to perform a calibration in the appropriate energy range that adequately probes all regions of the detector. Because detector response can vary greatly in various locations within the device, a spatially uniform calibration is important. We present a new method for calibration of liquid xenon (LXe) detectors, using the short-lived 83m-Kr. This source has transitions at 9.4 and 32.1 keV, and as a noble gas like Xe, it disperses uniformly in all regions of the detector. Even for low source activities, the existence of the two transitions provides a method of identifying the decays that is free of background. We find that at decreasing energies, the LXe light yield increases, while the amount of electric field quenching is diminished. Additionally, we show that if any long-lived radioactive backgrounds are introduced by this method, they will present less than 67E-6 events/kg/day in the next generation of LXe dark matter direct detection searchesComment: 9 pages, 9 figures. Accepted to Review of Scientific Instrument