21 research outputs found
A 83Krm Source for Use in Low-background Liquid Xenon Time Projection Chambers
We report the testing of a charcoal-based Kr-83m source for use in
calibrating a low background two-phase liquid xenon detector. Kr-83m atoms
produced through the decay of Rb-83 are introduced into a xenon detector by
flowing xenon gas past the Rb-83 source. 9.4 keV and 32.1 keV transitions from
decaying 83Krm nuclei are detected through liquid xenon scintillation and
ionization. The characteristics of the Kr-83m source are analyzed and shown to
be appropriate for a low background liquid xenon detector. Introduction of
Kr-83m allows for quick, periodic calibration of low background noble liquid
detectors at low energy.Comment: Updated to version submitted to JINS
Spatially uniform calibration of a liquid xenon detector at low energies using 83m-Kr
A difficult task with many particle detectors focusing on interactions below
~100 keV is to perform a calibration in the appropriate energy range that
adequately probes all regions of the detector. Because detector response can
vary greatly in various locations within the device, a spatially uniform
calibration is important. We present a new method for calibration of liquid
xenon (LXe) detectors, using the short-lived 83m-Kr. This source has
transitions at 9.4 and 32.1 keV, and as a noble gas like Xe, it disperses
uniformly in all regions of the detector. Even for low source activities, the
existence of the two transitions provides a method of identifying the decays
that is free of background. We find that at decreasing energies, the LXe light
yield increases, while the amount of electric field quenching is diminished.
Additionally, we show that if any long-lived radioactive backgrounds are
introduced by this method, they will present less than 67E-6 events/kg/day in
the next generation of LXe dark matter direct detection searchesComment: 9 pages, 9 figures. Accepted to Review of Scientific Instrument
Limits on the release of Rb isotopes from a zeolite based 83mKr calibration source for the XENON project
The isomer 83mKr with its half-life of 1.83 h is an ideal calibration source
for a liquid noble gas dark matter experiment like the XENON project. However,
the risk of contamination of the detector with traces of the much longer lived
mother isotop 83Rb (86.2 d half-life) has to be ruled out. In this work the
release of 83Rb atoms from a 1.8 MBq 83Rb source embedded in zeolite beads has
been investigated. To do so, a cryogenic trap has been connected to the source
for about 10 days, after which it was removed and probed for the strongest 83Rb
gamma-rays with an ultra-sensitive Germanium detector. No signal has been
found. The corresponding upper limit on the released 83Rb activity means that
the investigated type of source can be used in the XENON project and similar
low-background experiments as 83mKr generator without a significant risk of
contaminating the detector. The measurements also allow to set upper limits on
the possible release of the isotopes 84Rb and 86Rb, traces of which were
created alongside the production of 83Rb at the Rez cyclotron.Comment: 11 pages, 7 figures, submitted to Journal of Instrumentatio
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the
beta-electron energy spectrum near the endpoint of tritium beta-decay. An
integral energy analysis will be performed by an electro-static spectrometer
(Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a
volume of 1240 m^3, and a complex inner electrode system with about 120000
individual parts. The strong magnetic field that guides the beta-electrons is
provided by super-conducting solenoids at both ends of the spectrometer. Its
influence on turbo-molecular pumps and vacuum gauges had to be considered. A
system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter
strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out
at 300{\deg}C, and the performance of this system are presented in detail. The
vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is
demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start
at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure
A White Paper on keV Sterile Neutrino Dark Matter
We present a comprehensive review of keV-scale sterile neutrino Dark Matter,collecting views and insights from all disciplines involved - cosmology,astrophysics, nuclear, and particle physics - in each case viewed from boththeoretical and experimental/observational perspectives. After reviewing therole of active neutrinos in particle physics, astrophysics, and cosmology, wefocus on sterile neutrinos in the context of the Dark Matter puzzle. Here, wefirst review the physics motivation for sterile neutrino Dark Matter, based onchallenges and tensions in purely cold Dark Matter scenarios. We then round outthe discussion by critically summarizing all known constraints on sterileneutrino Dark Matter arising from astrophysical observations, laboratoryexperiments, and theoretical considerations. In this context, we provide abalanced discourse on the possibly positive signal from X-ray observations.Another focus of the paper concerns the construction of particle physicsmodels, aiming to explain how sterile neutrinos of keV-scale masses could arisein concrete settings beyond the Standard Model of elementary particle physics.The paper ends with an extensive review of current and future astrophysical andlaboratory searches, highlighting new ideas and their experimental challenges,as well as future perspectives for the discovery of sterile neutrinos
A White Paper on keV sterile neutrino Dark Matter
We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the -electron
energy spectrum near the endpoint of tritium -decay. An integral energy analysis will be performed
by an electro-static spectrometer (“Main Spectrometer”), an ultra-high vacuum vessel with a length
of 23.2 m, a volume of 1240m3, and a complex inner electrode system with about 120 000 individual
parts. The strong magnetic field that guides the -electrons is provided by super-conducting
solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum
gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of
non-evaporable getter strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out at 300 C, and the
performance of this system are presented in detail. The vacuum system has to maintain a pressure in
the 10 mbar range. It is demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start at the end of 2016