Gamma-induced background in the KATRIN main spectrometer

International audienceThe KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β -particles from tritium β -decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background

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

The design, construction, and commissioning of the KATRIN experiment

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns

Fission gas release from UO2 nuclear fuel: A review

Gaseous fission product generation, transport, and release can have a large impact on nuclear fuel performance, degrading fuel and fuel–cladding gap properties. Over the past several decades much progress has been made in understanding the key mechanisms of fission gas behavior through investigations with bulk reactor experiments and simplified analytical models. Concurrently, new mechanisms have come to light that can have a strong influence on gas release, especially the unexpected acceleration of fission gas release under high burn-up conditions. Additionally, novel modeling techniques, such as atomistic, mesoscale, and multiscale methods have joined the arsenal of investigative tools. In this review, existing research on the basic mechanisms of fission gas release during normal reactor operation is summarized, and critical areas where further work is needed are identified and discussed.JRC.G.I.5-Advanced Nuclear Knowledg

Effect of high dose fish oil supplementation on cerebral blood flow and cognitive performance in patients with mild cognitive impairment: a proof of concept study

Objective: The current study aimed to examine the effect of n-3 polyunsaturated fatty acids (PUFAs) on cerebral blood flow and age-related loss of cognitive functioning in subjects diagnosed with mild cognitive impairment (MCI). Design, setting and participants: A total of 20 patients with single or multiple domain MCI took part in this randomized, double-blind, placebo-controlled trial, wherein we investigated the effects of four weeks of daily supplementation with either a high pharmacological dose of 3 g eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) (n=10) or placebo (n=10) on cerebral blood flow and cognitive performance. Measurements: Cerebral blood flow and cortical oxygenation were measured by Transcranial Doppler and Near Infrared Spectroscopy together with blood pressure measurements using Finapres. Cognitive function was assessed by sensitive neuropsychological tests measuring reaction times, episodic memory and attention. Results: Daily supplementation with EPA+DHA for 4 weeks had no effect on cerebral hemodynamics or blood pressure. All subjects improved on most of the neuropsychological tests, but there was no difference between the fish oil and the placebo groups. Conclusions: In this randomized controlled trial in MCI patients, daily supplementation with EPA+DHA for four weeks had no effect on cerebral hemodynamics, blood pressure, or cognitive performanc

Comparison of Timor Uptake Heterogeneity Characterization Between Static and Parametric F-18-FDG PET Images in Non-Small Cell Lung Cancer

Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas