Characterization of high purity germanium point contact detectors with low net impurity concentration

High Purity germanium point-contact detectors have low energy thresholds and excellent energy resolution over a wide energy range, and are thus widely used in nuclear and particle physics. In rare event searches, such as neutrinoless double beta decay, the point-contact geometry is of particular importance since it allows for pulse-shape discrimination, and therefore for a significant background reduction. In this paper we investigate the pulse-shape discrimination performance of ultra-high purity germanium point contact detectors. It is demonstrated that a minimal net impurity concentration is required to meet the pulse-shape performance requirements

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Strain- and Adsorption-Dependent Electronic States and Transport or Localization in Graphene

The chapter generalizes results on influence of uniaxial strain and adsorption on the electron states and charge transport or localization in graphene with different configurations of imperfections (point defects): resonant (neutral) adsorbed atoms either oxygen- or hydrogen-containing molecules or functional groups, vacancies or substitutional atoms, charged impurity atoms or molecules, and distortions. To observe electronic properties of graphene-admolecules system, we applied electron paramagnetic resonance technique in a broad temperature range for graphene oxides as a good basis for understanding the electrotransport properties of other active carbons. Applied technique allowed observation of possible metal-insulator transition and sorption pumping effect as well as discussion of results in relation to the granular metal model. The electronic and transport properties are calculated within the framework of the tight-binding model along with the Kubo-Greenwood quantum-mechanical formalism. Depending on electron density and type of the sites, the conductivity for correlated and ordered adsorbates is found to be enhanced in dozens of times as compared to the cases of their random distribution. In case of the uniaxially strained graphene, the presence of point defects counteracts against or contributes to the band-gap opening according to their configurations. The band-gap behaviour is found to be nonmonotonic with strain in case of a simultaneous action of defect ordering and zigzag deformation. The amount of localized charge carriers (spins) is found to be correlated with the content of adsorbed centres responsible for the formation of potential barriers and, in turn, for the localization effects. Physical and chemical states of graphene edges, especially at a uniaxial strain along one of them, play a crucial role in electrical transport phenomena in graphene-based materials.Comment: 16 pages, 10 figure

ADC Nonlinearity Correction for the Majorana Demonstrator

Imperfections in analog-to-digital conversion (ADC) cannot be ignored when signal digitization requirements demand both wide dynamic range and high resolution, as is the case for the Majorana Demonstrator 76Ge neutrinoless double-beta decay search. Enabling the experiment's high-resolution spectral analysis and efficient pulse shape discrimination required careful measurement and correction of ADC nonlinearities. A simple measurement protocol was developed that did not require sophisticated equipment or lengthy data-taking campaigns. A slope-dependent hysteresis was observed and characterized. A correction applied to digitized waveforms prior to signal processing reduced the differential and integral nonlinearities by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay Q value

Atomic structures of TDP-43 LCD segments and insights into reversible or pathogenic aggregation.

The normally soluble TAR DNA-binding protein 43 (TDP-43) is found aggregated both in reversible stress granules and in irreversible pathogenic amyloid. In TDP-43, the low-complexity domain (LCD) is believed to be involved in both types of aggregation. To uncover the structural origins of these two modes of β-sheet-rich aggregation, we have determined ten structures of segments of the LCD of human TDP-43. Six of these segments form steric zippers characteristic of the spines of pathogenic amyloid fibrils; four others form LARKS, the labile amyloid-like interactions characteristic of protein hydrogels and proteins found in membraneless organelles, including stress granules. Supporting a hypothetical pathway from reversible to irreversible amyloid aggregation, we found that familial ALS variants of TDP-43 convert LARKS to irreversible aggregates. Our structures suggest how TDP-43 adopts both reversible and irreversible β-sheet aggregates and the role of mutation in the possible transition of reversible to irreversible pathogenic aggregation

Cosmogenic neutron production at the Sudbury Neutrino Observatory

Neutrons produced in nuclear interactions initiated by cosmic-ray muons present an irreducible background to many rare-event searches, even in detectors located deep underground. Models for the production of these neutrons have been tested against previous experimental data, but the extrapolation to deeper sites is not well understood. Here we report results from an analysis of cosmogenically produced neutrons at the Sudbury Neutrino Observatory. A specific set of observables are presented, which can be used to benchmark the validity of geant4 physics models. In addition, the cosmogenic neutron yield, in units of 10-4 cm2/(g·μ), is measured to be 7.28±0.09(stat)-1.12+1.59(syst) in pure heavy water and 7.30±0.07(stat)-1.02+1.40(syst) in NaCl-loaded heavy water. These results provide unique insights into this potential background source for experiments at SNOLAB

Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of 76Ge to Excited States of 76Se

The MAJORANA DEMONSTRATOR is searching for double-beta decay of 76Ge to excited states (E.S.) in 76Se using a modular array of high purity Germanium detectors. 76Ge can decay into three E.S.s of 76Se. The E.S. decays have a clear event signature consisting of a ββ-decay with the prompt emission of one or two γ-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of (0.56 2.1) ⋅ 1024 y. In particular, for the 2v transition to the first 0+ E.S. of 76Se, a lower half-life limit of 0.68 ⋅ 1024 at 90% CL was achieved

Confiabilidad de un instrumento para clasificar al recién nacido de acuerdo con la complejidad de la atención

Na maioria das maternidades, a classificação, a avaliação e a definição da unidade a encaminhar o recém-nascido (RN) após o nascimento são realizadas pelo médico. A\ud avaliação ocorre na sala de parto considerando: peso ao nascer; idade gestacional;\ud condutas que definem quadro clínico e doença. Este estudo observacional teve\ud como objetivo avaliar a confiabilidade de um instrumento de classificação de RN. A pesquisa foi realizada no berçário de um hospital público, São Paulo. Nove enfermeiras\ud aplicaram o instrumento a 63 RN, sendo duas simultaneamente em cada um dos\ud cinco setores do berçário. Verificou-se que o nível de concordância Kappa entre as enfermeiras foi excelente para a maioria das áreas de cuidado (69,0%). Concluiu-se que houve consenso e concordância das enfermeiras quanto ao instrumento ser completo, de fácil entendimento e aplicável, porém despende muito tempo. As enfermeiras reconhecem a importância do instrumento para o dimensionamento dos profissionais, organização e planejamento do cuidado.In most maternity units, the physician classifies, evaluates, and determines which unit will receive the newborn (NB) after birth. Evaluation occurs in the delivery room, taking into consideration the following factors: birth weight, gestational age, and behaviors that define the clinical picture and disease. This observational study evaluates the reliability of an NB classification instrument. The study was conducted at the nursery of a public hospital in São Paulo. Nine nurses applied the instrument to 63 NB, with two of the nurses working simultaneously in each of the nursery’s fi ve sectors. The Kappa level of agreement among the nurses was found to be excellent for most care areas\ud (69.0%). It was concluded that there was a consensus and agreement among the\ud nurses that the instrument was complete, easy to understand and applicable, but was\ud very time consuming. The nurses recognize the instrument’s importance for the allocation of professionals, organization, and care planning.En la mayoría de las maternidades la clasificación, la evaluación y la definición de la unidad para referir el recién nacido (RN), son realizadas por el médico. La evaluación se realiza en la sala de parto, considerando: peso al nacer, edad gestacional y conductas que definen el cuadro clínico y la enfermedad. Este estudio observacional tuvo como objetivo evaluar la confiabilidad de un instrumento de clasificación del RN. Fue realizada en el servicio de neonatología de un hospital público en Sao Paulo. Nueve enfermeras\ud aplicaron el instrumento a 63 RN, siendo aplicados dos de forma simultánea en los cinco sectores de la unidad neonatal. El nivel de concordancia Kappa fue excelente para la mayoría de las áreas de atención (69,0%). Se concluyó que hubo consenso y\ud concordancia entre las enfermeras, quienes expresaron que el instrumento es completo, fácil de entender y de aplicar, pero se necesita mucho tempo. Las enfermeras reconocen la importancia de este instrumento para dimensionar el número de profesionales, la organización y la planificación de la atención