22 research outputs found

    A novel detector system for KATRIN to search for keV-scale sterile neutrinos

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    International audienceSterile neutrinos appear in minimal extensions of the Standard Model of particle physics. If their mass is in the keV regime, they are viable dark matter candidates. One way to search for sterile neutrinos in a laboratory-based experiment is via the analysis of ÎČ-decay spectra, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the ÎČ-decay spectrum. The objective of the TRISTAN project is to extend the KATRIN setup with a new multi-pixel silicon drift detector system to search for a keV-scale sterile neutrino signal. In this paper we describe the requirements of such a new detector, and present first characterization measurement results obtained with a 7 pixel prototype system

    Etude de propriétés non standard du neutrino avec Borexino : mesure du taux de 8B solaire et caractérisation de la source de 144Ce pour tester l'hypothÚse stérile dans l'expérience SOX

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    Located in the Gran Sasso underground laboratory (LNGS), Borexino measures solar neutrinos for 10 years. Among solar neutrinos, 8B continuous spectrum (up to 17 MeV) enables to test the transition zone between vacuum and matter regime of the MSW effect. This new measurement increases by one order of magnitude the exposure with respect to previous Borexino publication. To do so, the entire active volume is considered in this analysis above 5 MeV. A new background has been identified and a radial fit is done above 3 and 5 MeV enabling to extract the neutrino component. Existence of a light sterile neutrino would have important consequences on astrophysics and cosmology. SOX is the only experiment aiming at testing this hypothesis using a punctual radioactive source. A 3-5.5 PBq 144Ce source is actually under production and will be positioned under Borexino in 2018. Precise knowledge of the source is one of the main challenge of this experiment, based on rate and shape neutrino measurement. Two critical parameters are the heat released by the source for activity measurement and the expected neutrino spectrum in the detector. We first describe the SOX experiment insisting on 144Ce source production. Then, we focus on Saclay installations dedicated to constrain radioactive contamination inside the source using representative samples. Alpha, gamma and mass spectroscopy calibration and simulation are discussed and competitive constrains are derived. A status on 144Ce beta shape measurements is done as well as presentation of future measurement.Le dĂ©tecteur Borexino, situĂ© au laboratoire souterrain du Gran Sasso (LNGS), mesure les neutrinos solaires depuis 10 ans. Parmi les neutrinos solaires, le spectre continu du 8B jusqu’à 17 MeV permet de tester la zone de transition de l’effet de rĂ©sonance dans la matiĂšre dit effet MSW. Cette nouvelle analyse augmente d’un ordre de grandeur la statistique par rapport Ă  la prĂ©cĂ©dente mesure de Borexino publiĂ©e en 2011. Pour ce faire, l’ensemble du volume scintillant a Ă©tĂ© inclus dans l’analyse, aucune coupure gĂ©omĂ©trique n’ayant Ă©tĂ© effectuĂ© au dessus de 5 MeV. Cela a permis l’identification d’un nouveau bruit de fond non pris en compte prĂ©cĂ©demment. L’ensemble des bruits de fond au dessus de 3 MeV est maintenant compris et la composante neutrino peut-ĂȘtre extraite d’un fit radial du dĂ©tecteur. Afin de tester l’existence d’un neutrino stĂ©rile lĂ©ger, une source de 3-5,5 PBq de 144Ce sera installĂ©e sous Borexino au dĂ©but de l’annĂ©e 2018 pour un an et demi de prise de donnĂ©es : c’est l’expĂ©rience CeSOX. Cette source est produite par PA MAYAK par purification de combustible nuclĂ©aire usagĂ©, par consĂ©quent les potentiels contaminants radioactifs sont trĂšs nombreux et peu contraints. Pour tester l’hypothĂšse stĂ©rile, une mesure en flux, une mesure en forme et une mesure combinĂ©e seront effectuĂ©es dans l’ensemble du dĂ©tecteur Borexino. Ces mesures sont fortement dĂ©pendantes de la connaissance intime de la source (composition, forme du spectre beta du 144Ce, Ă©nergie moyenne 144Ce et 144Pr). A cette fin, un spectromĂštre gamma a Ă©tĂ© spĂ©cifiquement Ă©talonnĂ© et entiĂšrement simulĂ© au CEA, Saclay. De mĂȘme un spectromĂštre beta a Ă©tĂ© dessinĂ©, assemblĂ©, simulĂ© et est en cours d’étalonnage. Finalement, des mesures de spectromĂ©trie alpha et de masse seront rĂ©alisĂ©s sur des Ă©chantillons reprĂ©sentatifs envoyĂ©s au CEA, Saclay afin de contraindre au mieux la composition de la source de 144Ce de SOX

    Design and characterization of Kerberos: a 48-channel analog pulse processing and data acquisition platform

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    A multi-channel data processing and acquisition system based on an analog ASIC (SFERA) has been designed and realized. The platform, called Kerberos, is suitable for the readout of large arrays of Silicon Drift Detector (SDD) for X-ray, -ray and electron spectroscopy applications. Each one of its 48 inputs is equipped with a 9th order semi-Gaussian shaping amplifier with programmable peaking time (0.5, 1, 2, 3, 4 and 6 ÎŒs). The pulse amplitudes are multiplexed into three 16-bit high linearity SAR ADCs and digitized into an Artix-7 FPGA module. Kerberos will be used for the characterization of monolithic SDD matrices for the TRISTAN project. Many different readout strategies can be selected on Kerberos Graphic User Interface: for TRISTAN it has been decided to use a full detector readout strategy, with maximum input throughput of about 166 kcount/s. This work presents a full characterization of this scalable platform and its use with several detectors types (SDD, micro-strips) in X-ray, gamma and beta spectroscopy

    Measurements with a TRISTAN prototype detector system at the “Troitsk nu-mass” experiment in integral and differential mode

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    International audienceSterile neutrinos emerge in minimal extensions of the Standard Model which can solve a number of open questions in astroparticle physics. For example, sterile neutrinos in the keV-mass range are viable dark matter candidates. Their existence would lead to a kink-like distortion in the tritium ÎČ-decay spectrum. In this work we report about the instrumentation of the Troitsk nu-mass experiment with a 7-pixel TRISTAN prototype detector and measurements in both differential and integral mode. The combination of the two modes is a key requirement for a precise sterile neutrino search, as both methods are prone to largely different systematic uncertainties. Thanks to the excellent performance of the TRISTAN detector at high rates, a sterile neutrino search up to masses of about 6 keV could be performed, which enlarges the previous accessible mass range by a factor of 3. Upper limits on the neutrino mixing amplitude in the mass range < 5.6 keV (differential) and < 6.6 keV (integral) are presented. These results demonstrate the feasibility of a sterile neutrino search as planned in the upgrade of the KATRIN experiment with the final TRISTAN detector and read-out system

    First operation of the KATRIN experiment with tritium

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    The determination of the neutrino mass is one of the major challenges in astroparticle physics today. Direct neutrino mass experiments, based solely on the kinematics of ÎČ ÎČ -decay, provide a largely model-independent probe to the neutrino mass scale. The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to directly measure the effective electron antineutrino mass with a sensitivity of 0.2 eV 0.2 eV (90% 90% CL). In this work we report on the first operation of KATRIN with tritium which took place in 2018. During this commissioning phase of the tritium circulation system, excellent agreement of the theoretical prediction with the recorded spectra was found and stable conditions over a time period of 13 days could be established. These results are an essential prerequisite for the subsequent neutrino mass measurements with KATRIN in 2019

    The SOX experiment hunts the sterile neutrino

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    The SOX (Short distance neutrino Oscillations with BoreXino) experiment aims to perform a resolutive measurement for testing the longstanding hypotesis of a sterile neutrino in the eV2 mass scale. A very intense and well calibrated 144Ce−144Pr antineutrino source will be placed under the large size and very low background Borexino detector at Laboratori Nazionali del Gran Sasso in Italy. Borexino demonstrated a such energy and position resolution that the disappearance experiment can be performed and the short distance oscillations might be directly observed. In this paper an overview of the key elements of the experiment is given and the expected sensitivity to determine the sterile neutrino mass is shown