Background Rejection in Highly Pixelated Solid-State Detectors

Highly pixelated solid-state detectors offer outstanding capabilities in the identification and suppression of backgrounds from natural radioactivity. We present the background-identification strategies developed for the DAMIC experiment, which employs silicon charge-coupled devices to search for dark matter. DAMIC has demonstrated the capability to disentangle and measure the activities of every $\beta$ emitter from the $^{32}$Si, $^{238}$U and $^{232}$Th decay chains in the silicon target. Similar strategies will be adopted by the Selena Neutrino Experiment, which will employ hybrid amorphous $^{82}$Se/CMOS imagers to perform spectroscopy of $\beta\beta$ decay and solar neutrinos. We present the proposed experimental strategy for Selena to achieve zero-background in a 100-ton-year exposure.Comment: Proceedings for Low Radioactivity Techniques (LRT) 202

Enfoque cooperativo y desempeño académico del área de Ciencias Sociales de los educandos del tercer grado de secundaria de la Institución Educativa María Auxiliadora – Huanta 2021

El objetivo de este trabajo de investigación fue el presente estudio está sustentado en el siguiente problema general ¿Cuál será el vínculo existente entre el enfoque cooperativo y el desempeño académico del área de Ciencias Sociales en los educandos del tercer grado de secundaria de la Institución Educativa María Auxiliadora – Huanta 2021?, en dicho estudio se formula como hipótesis principal que: Existe vínculo entre el enfoque cooperativo y el desempeño académico del área de Ciencias Sociales de los educandos del tercer grado de secundaria de la Institución Educativa María Auxiliadora – Huanta 2021, para el estudio de la variable enfoque cooperativo se empleó un cuestionario de medición directa, a un total de 148 educandos. Por otro lado, para cuantificar la variable desempeño académico, se recurrió a los registros de calificaciones o notas de los estudiantes del tercer grado de secundaria matriculados en el año lectivo 2021. El estudio presenta un procedimiento descriptivo no experimental correlacional, donde se empleó la prueba Rho – Spearman para calcular los coeficientes numéricos de correlación. La muestra desarrollada en el estudio, es no probabilístico censal de 148 educandos del tercer grado de secundaria de la Institución Educativa María Auxiliadora – Huanta 2021.The objective of this research work was the present study is based on the following general problem: What will be the link existing between the cooperative approach and the academic performance of the area of Sciences Social in the students of the third grade of secondary school of the Educational Institution María Auxiliadora – Huanta 2021?, in said study the main hypothesis is formulated that: There is a link between the cooperative approach and the academic performance of the area of Social Sciences of the students of the third grade of secondary school of the Institution Educativa María Auxiliadora – Huanta 2021, for the study of the focus variable cooperative, a direct measurement questionnaire was used, to a total of 148 students. On the other hand, to quantify the academic performance variable, records were used grades or grades of third grade high school students enrolled in the school year 2021. The study presents a non-experimental descriptive procedure correlational, where the Rho - Spearman test was used to calculate the coefficients correlation numbers. The sample developed in the study is non-probabilistic census of 148 third-grade students of the María Educational Institution Helper – Huanta 2021.ChosicaMetodología y evaluación educativ

Measurement of the ionization response of amorphous selenium with 122keV γ\gamma rays

We performed a measurement of the ionization response of 200 $\mu$m-thick amorphous selenium (aSe) layers under drift electric fields of up to 50 V/$\mu$m. The aSe target was exposed to ionizing radiation from a $^{57}$Co radioactive source and the ionization pulses were recorded with high resolution. Using the spectral line from the photoabsorption of 122keV $\gamma$ rays, we measure the charge yield in aSe and the line width as a function of drift electric field. From a detailed microphysics simulation of charge generation and recombination in aSe, we conclude that the strong dependence of recombination on the ionization track density provides the dominant contribution to the energy resolution in aSe. These results provide valuable input to estimate the sensitivity of a proposed next-generation search for the neutrinoless $\beta\beta$ decay of $^{82}$Se that aims to employ imaging sensors with an active layer of aSe.Comment: 16 pages, 11 figures. Prepared for submission to JINS

DAMIC at SNOLAB

We introduce the fully-depleted charge-coupled device (CCD) as a particle detector. We demonstrate its low energy threshold operation, capable of detecting ionizing energy depositions in a single pixel down to 50 eVee. We present results of energy calibrations from 0.3 keVee to 60 keVee, showing that the CCD is a fully active detector with uniform energy response throughout the silicon target, good resolution (Fano ~0.16), and remarkable linear response to electron energy depositions. We show the capability of the CCD to localize the depth of particle interactions within the silicon target. We discuss the mode of operation and unique imaging capabilities of the CCD, and how they may be exploited to characterize and suppress backgrounds. We present the first results from the deployment of 250 um thick CCDs in SNOLAB, a prototype for the upcoming DAMIC100. DAMIC100 will have a target mass of 0.1 kg and should be able to directly test the CDMS-Si signal within a year of operation.Comment: 13 pages, 12 figures, proceedings prepared for 13th International Conference on Topics in Astroparticle and Underground Physics (TAUP2013

The DAMIC-M experiment: Status and first results

The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted silicon charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called “hidden sector.” A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Skipper-CCD Sensors for the Oscura Experiment: Requirements and Preliminary Tests

Oscura is a proposed multi-kg skipper-CCD experiment designed for a dark matter (DM) direct detection search that will reach unprecedented sensitivity to sub-GeV DM-electron interactions with its 10 kg detector array. Oscura is planning to operate at SNOLAB with 2070 m overburden, and aims to reach a background goal of less than one event in each electron bin in the 2-10 electron ionization-signal region for the full 30 kg-year exposure, with a radiation background rate of 0.01 dru. In order to achieve this goal, Oscura must address each potential source of background events, including instrumental backgrounds. In this work, we discuss the main instrumental background sources and the strategy to control them, establishing a set of constraints on the sensors' performance parameters. We present results from the tests of the first fabricated Oscura prototype sensors, evaluate their performance in the context of the established constraints and estimate the Oscura instrumental background based on these results

Early Science with the Oscura Integration Test

Oscura is a planned light-dark matter search experiment using Skipper-CCDs with a total active mass of 10 kg. As part of the detector development, the collaboration plans to build the Oscura Integration Test (OIT), an engineering test experiment with 10% of the Oscura's total mass. Here we discuss the early science opportunities with the OIT to search for millicharged particles (mCPs) using the NuMI beam at Fermilab. mCPs would be produced at low energies through photon-mediated processes from decays of scalar, pseudoscalar, and vector mesons, or direct Drell-Yan productions. Estimates show that the OIT would be a world-leading probe for low-mass mCPs.Comment: 21 pages, 13 figure

Study on pep and CNO solar neutrino interaction rates in Borexino

We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.28±0.56(stat)± 0.26(syst) day-1(100ton)-1. Assuming the pep neutrino flux predicted by the Standard Solar Model, we obtained a constraint on the CNO solar neutrino interaction rate of <8.3 day-1(100 ton)-1 (95% C.L.). The absence of the solar neutrino signal is disfavored at 99.99997% C.L., while the absence of the pep neutrino signal is disfavored at 98% C.L. The necessary sensitivity was achieved due to the extremely low levels of radioactive contamination in Borexino and by adopting data analysis techniques for the rejection of cosmogenic 11C, the dominant background in the 1-2 MeV region. Assuming the LMA-MSW solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of (1.7±0.3)×108 cm-2s-1 and <7.9×108 cm-2s-1 (95% C.L.), respectively, in agreement with both the High and Low Metallicity Standard Solar Models. These results represent the first direct evidence of the pep neutrino signal and the strongest constraint of the CNO solar neutrino flux to date [1]. [1] G. Bellini et al. First evidence of pep solar neutrinos by direct detection in Borexino. Phys.Rev.Lett., 108:051302, 2012