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

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 β-decay spectra, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the β-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'hypothèse stérile dans l'expérience SOX

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 détecteur Borexino, situé 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 résonance dans la matière dit effet MSW. Cette nouvelle analyse augmente d’un ordre de grandeur la statistique par rapport à la précédente mesure de Borexino publiée en 2011. Pour ce faire, l’ensemble du volume scintillant a été inclus dans l’analyse, aucune coupure géométrique n’ayant été effectué au dessus de 5 MeV. Cela a permis l’identification d’un nouveau bruit de fond non pris en compte précédemment. L’ensemble des bruits de fond au dessus de 3 MeV est maintenant compris et la composante neutrino peut-être extraite d’un fit radial du détecteur. Afin de tester l’existence d’un neutrino stérile léger, une source de 3-5,5 PBq de 144Ce sera installée sous Borexino au début de l’année 2018 pour un an et demi de prise de données : c’est l’expérience CeSOX. Cette source est produite par PA MAYAK par purification de combustible nucléaire usagé, par conséquent les potentiels contaminants radioactifs sont très nombreux et peu contraints. Pour tester l’hypothèse stérile, une mesure en flux, une mesure en forme et une mesure combinée seront effectuées dans l’ensemble du détecteur Borexino. Ces mesures sont fortement dépendantes de la connaissance intime de la source (composition, forme du spectre beta du 144Ce, énergie moyenne 144Ce et 144Pr). A cette fin, un spectromètre gamma a été spécifiquement étalonné et entièrement simulé au CEA, Saclay. De même un spectromètre beta a été dessiné, assemblé, simulé et est en cours d’étalonnage. Finalement, des mesures de spectrométrie alpha et de masse seront réalisés sur des échantillons représentatifs envoyés au CEA, Saclay afin de contraindre au mieux la composition de la source de 144Ce de SOX

Development of a Monolithic 47-Pixel SDD-Based Module for Electron Detection

We present the design and preliminary X-ray characterization of a detection module based on a monolithic 47-pixel Silicon Drift Detector (SDD) matrix. The detection system is developed in the context of the TRISTAN project, aiming at proving the existence of a keV-mass range sterile neutrino by the measurement of the tritium beta-decay spectrum. In particular, the 47-pixel module is an important project milestone due to its installation for testing and validation inside KATRIN’s (Karlsruhe Tritium Neutrino experiment) monitor spectrometer. A natural evolution of the module will be its 166-pixel version, the fundamental block constituting the future TRISTAN focal plane detector containing a total of 3486 SDD pixel

Development of a silicon drift detector system for the TRISTAN project

Sterile neutrinos are a minimal extension of the Standard Model of Particle Physics. If their mass is in the kilo-electron-volt regime, they are viable dark matter candidates. One way to search for sterile neutrinos in a laboratory-based experiment is via tritium beta decay, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the spectrum. The objective of the TRISTAN project is to extend the KATRIN setup with a novel multi-pixel silicon drift detector system to search for a keV-scale sterile neutrino signal. First seven-pixel prototype detectors were produced and characterized with radioactive x-ray and electron sources. The next prototype generation with 166 pixels is currently in production and will be ready at the end of 2018. This poster describes the requirements of the novel TRISTAN detector system and presents the technical realization of the first prototypes.</p

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

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 μs). 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

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

Abstract Sterile 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 β-decay spectra, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the β-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.</jats:p

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

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 β-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