EDELWEISS-II Dark Matter Search : status and first results

The EDELWEISS II experiment is devoted to the search for Weakly Interacting Massive Particles (WIMP) that would constitute the Dark Matter halo of our Galaxy. For this purpose, the experiment uses cryogenic germanium detectors, cooled down at 20 mK, in which the collision of a WIMP with an atomic nucleus produces characteristic signals in terms of ionization and elevation of temperature. We will present the preliminary results of the first operation of the detectors installed in the underground laboratory of the Frejus Tunnel (LSM), attesting to the very low radioactive background conditions achieved so far. New detectors, with a special electrode design for active rejection of surface events, have been shown to be suited for searches of WIMPs with scattering cross-sections on nucleon well below 10-8 pb. Preliminary results of WIMP search performed with a first set of these detectors are presented.Comment: 4 pages, to appear in the proceedings of the TAUP09 conference (Rome, July 1st-5th 2009

Textbook Broke: Textbook Affordability as a Social Justice Issue

In light of rising textbook prices, open education resources (OER) have been shown to decrease non-tuition costs, while simultaneously increasing academic access, student performance, and time-to-graduation rates. Yet very little research to date has explored OER’s specific impact on those who are presumed to benefit most from this potential: historically underserved students. This reality has left a significant gap of understanding in the current body of literature, resulting in calls for more empirically-based examinations of OER through a social justice lens. For each of these reasons, this study explored the impact of OER and textbook pricing among racial/ethnic minority students, low-income students, and first-generation college students at a four-year Hispanic Serving Institution (HSI) in Southern California. Drawing upon more than 700 undergraduate surveys, our univariate, bivariate and multivariate results revealed textbook costs to be a substantial barrier for the vast majority of students. However, those barriers were even more significant among historically underserved college students; thus, confirming textbook affordability as a redistributive justice issue, and positing OER as a potential avenue for realizing a more socially just college experience

Latest results of the EDELWEISS experiment

The EDELWEISS experiment is a direct detection Dark Matter Search, under the form of WIMPs. It uses heat and ionization Ge cryogenic detectors. We present the latest results obtained by the experiment with three new 320g bolometers. At present, EDELWEISS I is the most sensitive experiment for all WIMP masses compatible with accelerator constraints (Mwimp>30 GeV/c^2). We also briefly describe the status of the second stage EDELWEISS II involving initially 10 kg of detectors aiming a gain of two orders of magnitude in sensitivity.Comment: 4 pages, 3 figures, to appear in the proceedings of the Rencontres de Moriond - Cosmology : Exploring the Universe 200

2022 Oregon State University Student Textbooks and Course Materials Survey: Results and Findings

The summary and findings of the 2022 OSU student textbook and course materials survey. This survey was run in March 2022 by the Open Education Resources Unit. It is a derivative of the Florida Virtual Libraries 2018 Student Textbook and COurse Materials survey. The survey inquires about student access to their course materials, the cost of their textbooks, and what the implications are when student do not purchase their textbooks

Development of Total Decay Energy Spectrometry of α-Emitting Radionuclides Using Metallic Magnetic Calorimeters

International audienceTotal decay energy spectrometry with cryogenic detectors is a promising technique for radionuclide analysis of α-emitting nuclides. The radioactive sample is embedded in the detector absorber, and the total decay energy for each disintegration is measured as a temperature elevation. We are developing this technique with metallic magnetic calorimeters (MMCs). The main condition of this technique is a detection efficiency close to unity. However, some α-emitting nuclides emit intense γ-rays that can partially escape from the absorber. So a feasibility study for several nuclides has been carried out based on Monte Carlo simulations of the detection efficiency and numerical calculations of the expected energy resolution to identify the radionuclides that can potentially be measured. Furthermore, an MMC prototype has been built and tested. The total decay energy spectrum of Po-210 was measured, and a FWHM energy resolution of 1.25 keV at 5.4 MeV was obtained and a Gaussian width at half maximum of 0.827 (5) keV. The baseline FWHM energy resolution is 207 eV, consistent with the resolution obtained on low-energy L X-rays in the same spectrum at 14 keV

High-Resistivity Transition-Edge Sensor Modeling and Expected Performances

International audienceHigh spectral resolution detectors based on low-resistivity transition-edge sensors (TES) are being developed for future X-ray spatial observatories, but difficulties (cryogenics limitations) are to be expected in next generation’s detectors with even more pixels. A new technology, the high-resistivity TES (HRTES), is likely to offer similar performance to existing TES when associated to an active electrothermal feedback, adding the possibility of moving the readout electronics to a 2.5 K stage of the cryocooler. This work aims to investigate HRTES by making a precise model of the device, comparing it to experimental measurements, and deducing its performance potential

The First Tests of a Large-Area Light Detector Equipped with Metallic Magnetic Calorimeters for Scintillating Bolometers for the LUMINEU Neutrinoless Double Beta Decay Search

International audienceFuture rare-event searches using scintillating crystals need very low background levels for high sensitivity, however, unresolved pile-up can limit this. We present the design and fabrication of large-area photon detectors based on metallic magnetic calorimeters (MMCs), optimized for fast rise times to resolve close pile-up. The first prototypes have been characterized using Fe-55 X-rays and ZnMoO$_{4}$ crystal scintillation light. A fast intrinsic rise time of 25–30  \upmu s has been measured and has been compared to the 250  \upmu s scintillation light pulse rise time constant. The difference indicates that the scintillation process limits the light pulse rise time. The fast rise time allows for a reduction of background due to close pile-up events as well as the study of the inherent crystal scintillation process. MMC-based photon detectors are shown to be a promising tool for scintillating crystal based rare event searches

X-ray detectors for the BabyIAXO solar axion search

International audienceBabyIAXO is a helioscope under construction to search for an emission of the axion particle from the Sun. At the same time it serves as an intermediate stage towards the International Axion Observatory (IAXO). An integral component of this experiment is a low background X-ray detector with a high efficiency in the 1–10 keV energy range. Micromegas detectors are considered as baseline technology for BabyIAXO thanks to the relatively high efficiency and very low background level. Other detector technologies developed to reach better energy resolution while maintaining high efficiency and low background level are also under study. In this paper, we review the BabyIAXO design and present the analysis of data taken with the prototype of an IAXO Micromegas detector. A background level of 8.8×10−7counts keV−1cm−2s−1 was reached

X-ray detectors for the BabyIAXO solar axion search

BabyIAXO is a helioscope under construction to search for an emission of the axion particle from the Sun. At the same time it serves as an intermediate stage towards the International Axion Observatory (IAXO). An integral component of this experiment is a low background X-ray detector with a high efficiency in the 1–10 keV energy range. Micromegas detectors are considered as baseline technology for BabyIAXO thanks to the relatively high efficiency and very low background level. Other detector technologies developed to reach better energy resolution while maintaining high efficiency and low background level are also under study. Inthis paper, we review the BabyIAXO design and present the analysis of data taken with he prototype of an IAXO Micromegas detector. A background level of 8.8 × 10−7 counts keV−1 cm−2 s−1 was reached

Background discrimination with a Micromegas detector prototype and veto system for BabyIAXO

International audienceIn this paper we present measurements performed with a Micromegas X-ray detector setup. The detector is a prototype in the context of the BabyIAXO helioscope, which is under construction to search for an emission of the hypothetical axion particle from the sun. An important component of such a helioscope is a low background X-ray detector with a high efficiency in the 1-10 keV energy range. The goal of the measurement was to study techniques for background discrimination. In addition to common techniques we used a multi-layer veto system designed to tag cosmogenic neutron background. Over an effective time of 52 days, a background level of $8.6 \times 10^{-7}\,\text{counts keV}^{-1}\,\text{cm}^{-2} \, \text{s}^{-1}$ was reached in a laboratory at above ground level. This is the lowest background level achieved at surface level. In this paper we present the experimental setup, show simulations of the neutron-induced background, and demonstrate the process to identify background signals in the data. Finally, prospects to reach lower background levels down to $10^{-7} \, \text{counts keV}^{-1} \, \text{cm}^{-2} \, \text{s}^{-1}$ will be discussed