Sterile neutrinos are a minimal extension of the Standard Model of Particle Physics. A promising model-independent way to search for sterile neutrinos is via high-precision beta spectroscopy. The ...Karlsruhe Tritium Neutrino (KATRIN) experiment, equipped with a novel multi-pixel silicon drift detector focal plane array and read-out system, named the TRISTAN detector, has the potential to supersede the sensitivity of previous laboratory-based searches. In this work we present the characterization of the first silicon drift detector prototypes with electrons and we investigate the impact of uncertainties of the detector's response to electrons on the final sterile neutrino sensitivity.
ADC non-linearities are a major systematic effect in the search for keV-scale sterile neutrinos with tritium \(\beta\)-decay experiments like KATRIN. They can significantly distort the spectral shape ...and thereby obscure the tiny kink-like signature of a sterile neutrino. In this work we demonstrate various mitigation techniques to reduce the impact of ADC non-linearities on the tritium \(\beta\)-decay spectrum to a level of \(<\) ppm. The best results are achieved with a multi-pixel (\(\geq10^4\) pixels) detector using full waveform digitization. In this case, active-to-sterile mixing angles of the order of \(\sin^2 \theta = 10^{-7}\) would be accessible from the viewpoint of ADC non-linearities. With purely peak-sensing ADCs a comparable sensitivity could be reached with highly linear ADCs, sufficient non-linearity corrections or by increasing the number of pixels to \(\geq 10^5\).
Phys. Rev. D 91, 042005 (2015) Sterile neutrinos in the mass range of a few keV are candidates for both cold
and warm dark matter. An ad-mixture of a heavy neutrino mass eigenstate to the
electron ...neutrino would result in a minuscule distortion - a 'kink' - in a
$\beta$-decay spectrum. In this paper we show that a wavelet transform is a
very powerful shape analysis method to detect this signature. For a tritium
source strength, similar to what is expected from the KATRIN experiment, a
statistical sensitivity to active-to-sterile neutrino mixing down to $\sin^2
\theta= 10^{-6}$ ($90\%$ CL) can be obtained after 3 years of measurement time.
It is demonstrated that the wavelet approach is largely insensitive to
systematic effects that result in smooth spectral modifications. To make full
use of this analysis technique a high resolution measurement (FWHM of
$\sim100$~eV) of the tritium $\beta$-decay spectrum is required.
Sterile neutrinos in the mass range of a few keV are candidates for both cold and warm dark matter. An ad-mixture of a heavy neutrino mass eigenstate to the electron neutrino would result in a ...minuscule distortion - a 'kink' - in a \(\beta\)-decay spectrum. In this paper we show that a wavelet transform is a very powerful shape analysis method to detect this signature. For a tritium source strength, similar to what is expected from the KATRIN experiment, a statistical sensitivity to active-to-sterile neutrino mixing down to \(\sin^2 \theta= 10^{-6}\) (\(90\%\) CL) can be obtained after 3 years of measurement time. It is demonstrated that the wavelet approach is largely insensitive to systematic effects that result in smooth spectral modifications. To make full use of this analysis technique a high resolution measurement (FWHM of \(\sim100\)~eV) of the tritium \(\beta\)-decay spectrum is required.
First operation of the KATRIN experiment with tritium Altenmüller, Konrad; Arenz, Marius; Baek, Woo-Jeong ...
The European physical journal. C, Particles and fields,
03/2020, Letnik:
80, Številka:
3
Journal Article
Recenzirano
Odprti dostop
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
β
-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
(
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.
Persistent developmental stuttering (PDS) disrupts speech fluency in about 1% of adults. Very little is known on the integrity of sensory representations of speech organs in PDS, even though many ...models of speech production assume an intact sensory feedback from speech organs to the brain. Here we studied somatosensory evoked potentials in adults who stutter, with the aim of probing the integrity of sensory pathways. In addition, we tested the processing of dual sensory input, to address a putative link between stuttering and focal dystonia. In 15 adults who stutter (AWS, aged 15-55 years; 3 females) and 14 matched fluent speaking adults (ANS), we recorded somatosensory evoked potentials (SEPs) at C5' and C6' induced by stimulating separately or simultaneously the tongue or the cheek at the corner of the mouth. We determined latencies (N13, P19, and N27) and peak-to-peak amplitudes (N13-P19, P19-N27). We divided amplitudes from simultaneous stimulation by the sum of those from separate stimulation. Amplitude ratios did not differ between groups, indicating normal processing of dual sensory input. This does not support a clinical analogy between focal dystonia and persistent stuttering. SEP latencies as a measure of transmission speed in sensory pathways were significantly shorter in stuttering subjects than in fluent speaking participants, however, this might have been related to a trend for a height difference between groups, and was not confirmed in a replication dataset. In summary, we did not find evidence for dystonia-like sensory overflow of tongue representations in AWS.
The Karlsruhe Tritium Neutrino (KATRIN) experiment aims at measuring the effective electron neutrino mass with a sensitivity of 0.2 eV/c2, i.e., improving on previous measurements by an order of ...magnitude. Neutrino mass data taking with KATRIN commenced in early 2019, and after only a few weeks of data recording, analysis of these data showed the success of KATRIN, improving on the known neutrino mass limit by a factor of about two. This success very much could be ascribed to the fact that most of the system components met, or even surpassed, the required specifications during long-term operation. Here, we report on the performance of the laser Raman (LARA) monitoring system which provides continuous high-precision information on the gas composition injected into the experiment’s windowless gaseous tritium source (WGTS), specifically on its isotopic purity of tritium—one of the key parameters required in the derivation of the electron neutrino mass. The concentrations cx for all six hydrogen isotopologues were monitored simultaneously, with a measurement precision for individual components of the order 10−3 or better throughout the complete KATRIN data taking campaigns to date. From these, the tritium purity, εT, is derived with precision of <10−3 and trueness of <3 × 10−3, being within and surpassing the actual requirements for KATRIN, respectively.
Le mode de propagation complexe des fissures courtes observé dans les métaux ductiles sous chargement cyclique est généralement attribué à différents mécanismes de stabilisation intervenant à ...l’échelle de la microstructure, l’échelle mésoscopique. Parmi ces mécanismes, l’interaction de la fissure avec la microstructure de dislocation semble jouer un rôle majeur. La dynamique des dislocations contrôle la déformation plastique et le transfert de chaleur qui lui est associé et réduit ainsi la quantité d’énergie élastique stockée dans le matériau. De plus, la microstructure de dislocations peut « écranter » le champ élastique induit par la fissure par son propre champ de contraintes et modifier la géométrie de la fissure par l’émoussement des surfaces en pointe. Pour la première fois, ces mécanismes sont étudiés avec des simulations 3D de Dynamique des Dislocation avec le modèle Discrete-Continu. Trois orientations de fissure sont testées sous un chargement monotone en traction, promouvant une ouverture en fond de fissure en mode I. De manière surprenante, les simulations montrent que les effets d’écrantage et d’émoussement n’ont pas un rôle clé dans la stabilisation des fissures testées en mode I. Le mécanisme principal se trouve être la capacité du matériau à se déformer plastiquement sans mettre en oeuvre un durcissement important par le mécanisme de la forêt. Des recherches supplémentaires sur deux effets de taille confirment ces résultats et montrent également la contribution mineure d’une densité de dislocations polarisées et du durcissement cinématique associé à la stabilisation des fissures.
The erratic behaviour of short cracks propagation under low cyclic loading in ductile metals is commonly attributed to a complex interplay between stabilisation mechanisms that occur at the mescopic scale. Among these mechanisms, the interaction with the existing dislocation microstructure play a major role. The dislocation microstructure is source of plastic deformation and heat transfer that reduce the specimen stored elastic energy, screen the crack field due to its self generated stress field or change the crack geometry through blunting mechanisms. For the first time, these mechanisms are investigated with 3D-DD simulations using the Discrete- Continuous Model, modelling three different crack orientations under monotonic traction loading promoting mode I crack opening.Surprisingly, screening and blunting effects do not seem to have a key role on mode I crack stabilisation. Rather, the capability of the specimen to deform plastically without strong forest hardening is found to be the leading mechanism. Additional investigations of two different size effects confirm those results and show the minor contribution of a polarised dislocations density and the associated kinematic hardening on crack stabilisation.
Parahydrogen-Induced Polarization (PHIP) is a potent technique for generating
target molecules with high nuclear spin polarization. The PHIP process involves
a chemical reaction between parahydrogen ...and a target molecule, followed by the
transformation of nuclear singlet spin order into magnetization of a designated
nucleus through magnetic field manipulations. Although the
singlet-to-magnetization polarization transfer process works effectively at
moderate concentrations, it is observed to become much less efficient at high
molar polarization, defined as the product of polarization and concentration.
This strong dependence on the molar polarization is attributed to interference
from the field produced by the sample's magnetization during polarization
transfer, which leads to complex dynamics and can severely impact the
scalability of the technique. We address this challenge with a pulse sequence
that negates the influence of the distant dipolar field, while simultaneously
achieving singlet-to-magnetization polarization transfer to the desired target
spins, free from restrictions on the molar polarization.
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