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

Gaseous time projection chambers for rare event detection: Results from the T-REX project. II. Dark matter

As part of the T-REX project, a number of R&D and prototyping activities have been carried out during the last years to explore the applicability of Micromegas-read gaseous TPCs in rare event searches like double beta decay (DBD), axion research and low-mass WIMP searches. While in the companion paper we focus on DBD, in this paper we focus on the results regarding the search for dark matter candidates, both axions and WIMPs. Small ultra-low background Micromegas detectors are used to image the x-ray signal expected in axion helioscopes like CAST at CERN. Background levels as low as $0.8\times 10^{-6}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$ have already been achieved in CAST while values down to $\sim10^{-7}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$ have been obtained in a test bench placed underground in the Laboratorio Subterr\'aneo de Canfranc. Prospects to consolidate and further reduce these values down to $\sim10^{-8}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$will be described. Such detectors, placed at the focal point of x-ray telescopes in the future IAXO experiment, would allow for 10$^5$ better signal-to-noise ratio than CAST, and search for solar axions with $g_{a\gamma}$ down to few 10$^{12}$ GeV$^{-1}$, well into unexplored axion parameter space. In addition, a scaled-up version of these TPCs, properly shielded and placed underground, can be competitive in the search for low-mass WIMPs. The TREX-DM prototype, with $\sim$0.300 kg of Ar at 10 bar, or alternatively $\sim$0.160 kg of Ne at 10 bar, and energy threshold well below 1 keV, has been built to test this concept. We will describe the main technical solutions developed, as well as the results from the commissioning phase on surface. The anticipated sensitivity of this technique might reach $\sim10^{-44}$ cm$^2$ for low mass ($<10$ GeV) WIMPs, well beyond current experimental limits in this mass range.Comment: Published in JCAP. New version with erratum incorporated (new figure 14

Lessons from the operation of the "Penning-Fluorescent" TPC and prospects

We have recently reported the development of a new type of high-pressure Xenon time projection chamber operated with an ultra-low diffusion mixture and that simultaneously displays Penning effect and fluorescence in the near-visible region (300 nm). The concept, dubbed `Penning-Fluorescent' TPC, allows the simultaneous reconstruction of primary charge and scintillation with high topological and calorimetric fidelity

Molecular analysis of the BRCA1 and BRCA2 genes in 32 breast and/or ovarian cancer Spanish families

It is estimated that about 5–10% of breast cancer cases may be due to inherited predisposition. Until now, two main susceptibility genes have been identified: BRCA1 and BRCA2. The first linkage and mutational studies suggested that mutations in these two genes would account for the majority of high-risk breast cancer families, but recent studies show how the proportion of families due to BRCA1 or BRCA2 mutations strongly depends on the population and the types of family analyzed. It is now clear that, in the context of families with a modest cancer profile, which are the most commonly found in the clinical practice, the percentage of mutations found is much lower than that suggested by the first studies. In the present study, we analyze a group of 32 Spanish families, which contatined at least three cases of female breast cancer (at least one of them diagnosed before the age of 50 years), for the presence of mutations in the BRCA genes. The total proportion of mutations was low (25%), although the percentage of mutations in the BRCA1 and BRCA2 genes was higher, considering the breast and ovarian cancer families and the male breast cancer families respectively. Our results are in agreement with the idea that a great proportion of moderate-risk cancer families could be due to low penetrance susceptibility genes distinct from BRCA1 or BRCA2. © 2000 Cancer Research Campaig

The X-ray Telescope of CAST

The Cern Axion Solar Telescope (CAST) is in operation and taking data since 2003. The main objective of the CAST experiment is to search for a hypothetical pseudoscalar boson, the axion, which might be produced in the core of the sun. The basic physics process CAST is based on is the time inverted Primakoff effect, by which an axion can be converted into a detectable photon in an external electromagnetic field. The resulting X-ray photons are expected to be thermally distributed between 1 and 7 keV. The most sensitive detector system of CAST is a pn-CCD detector combined with a Wolter I type X-ray mirror system. With the X-ray telescope of CAST a background reduction of more than 2 orders off magnitude is achieved, such that for the first time the axion photon coupling constant g_agg can be probed beyond the best astrophysical constraints g_agg < 1 x 10^-10 GeV^-1.Comment: 19 pages, 25 figures and images, replaced by the revised version accepted for publication in New Journal of Physic

Changes in melatonin concentrations in seminal plasma are not correlated with testosterone or antioxidant enzyme activity when rams are located in areas with an equatorial photoperiod

In temperate climates, photoperiod and melatonin regulate ram reproduction, modulating hormonal secretions, sperm quality, and seminal plasma composition. Information on the effect of an equatorial photoperiod (12L:12D) on ram reproduction, however, is scarce, and no data on hormonal concentrations and antioxidant enzyme activity in seminal plasma have been reported. Thus, the variation was investigated of melatonin and its relationship with testosterone and antioxidant enzyme activity in the seminal plasma of three sheep breeds in Colombia, when there was a consistent photoperiod during two dry and two rainy seasons per year. Semen was collected once a week from 12 mature rams (four of each breed: Colombian Creole, Hampshire, and Romney Marsh). Seminal plasma was obtained by centrifugation. The concentration of melatonin and testosterone were quantified along with the enzymatic activity of glutathione peroxidase (GPx), glutathione reductase (GRD), and catalase (CAT). Correlation analyses between melatonin and testosterone concentrations or enzymatic activity were also performed. Melatonin concentration was affected by season (P < 0.05) but not breed, with lesser concentrations in the first rainy season. Testosterone concentration, however, was affected by breed and season, with greater concentrations (P < 0.01) in the Hampshire and Romney Marsh rams during the second dry season. Regarding antioxidant enzyme activity, there was only seasonal variation in GPx activity (P < 0.05). When correlation analyses were used for data assessments, there was a negative correlation between melatonin and testosterone concentrations in Hampshire rams. In conclusion, melatonin concentrations in seminal plasma of rams that were located in an area with an equatorial photoperiod was affected by the climatological season but there was no positive correlation with testosterone concentration or antioxidant enzyme activity

A multistate model and its standalone tool to predict hospital and ICU occupancy by patients with COVID-19

Objective: This study aims to build a multistate model and describe a predictive tool for estimating the daily number of intensive care unit (ICU) and hospital beds occupied by patients with coronavirus 2019 disease (COVID-19). Material and methods: The estimation is based on the simulation of patient trajectories using a multistate model where the transition probabilities between states are estimated via competing risks and cure models. The input to the tool includes the dates of COVID-19 diagnosis, admission to hospital, admission to ICU, discharge from ICU and discharge from hospital or death of positive cases from a selected initial date to the current moment. Our tool is validated using 98,496 cases positive for severe acute respiratory coronavirus 2 extracted from the Aragón Healthcare Records Database from July 1, 2020 to February 28, 2021. Results: The tool demonstrates good performance for the 7- and 14-days forecasts using the actual positive cases, and shows good accuracy among three scenarios corresponding to different stages of the pandemic: 1) up-scenario, 2) peak-scenario and 3) down-scenario. Long term predictions (two months) also show good accuracy, while those using Holt-Winters positive case estimates revealed acceptable accuracy to day 14 onwards, with relative errors of 8.8%. Discussion: In the era of the COVID-19 pandemic, hospitals must evolve in a dynamic way. Our prediction tool is designed to predict hospital occupancy to improve healthcare resource management without information about clinical history of patients. Conclusions: Our easy-to-use and freely accessible tool (https://github.com/peterman65) shows good performance and accuracy for forecasting the daily number of hospital and ICU beds required for patients with COVID-19