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1,526
result(s) for
"Lindner, M."
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Novel constraints on neutrino physics beyond the standard model from the CONUS experiment
by
Bonhomme, A.
,
Strecker, H.
,
Buck, C.
in
Beyond Standard Model
,
Classical and Quantum Gravitation
,
Coherent scattering
2022
A
bstract
The measurements of coherent elastic neutrino-nucleus scattering (CE
ν
NS) experiments have opened up the possibility to constrain neutrino physics beyond the standard model of elementary particle physics. Furthermore, by considering neutrino-electron scattering in the keV-energy region, it is possible to set additional limits on new physics processes. Here, we present constraints that are derived from Conus germanium data on beyond the standard model (BSM) processes like tensor and vector non-standard interactions (NSIs) in the neutrino-quark sector, as well as light vector and scalar mediators. Thanks to the realized low background levels in the C
onus
experiment at ionization energies below 1 keV, we are able to set the world’s best limits on tensor NSIs from CE
ν
NS and constrain the scale of corresponding new physics to lie above 360 GeV. For vector NSIs, the derived limits strongly depend on the assumed ionization quenching factor within the detector material, since small quenching factors largely suppress potential signals for both, the expected standard model CE
ν
NS process and the vector NSIs. Furthermore, competitive limits on scalar and vector mediators are obtained from the CE
ν
NS channel at reactor-site which allow to probe coupling constants as low as 5 ∙ 10
−
5
of low mediator masses, assuming the currently favored quenching factor regime. The consideration of neutrino-electron scatterings allows to set even stronger constraints for mediator masses below ∼ 1 MeV and ∼ 10 MeV for scalar and vector mediators, respectively.
Journal Article
Direct measurement of the ionization quenching factor of nuclear recoils in germanium in the keV energy range
2022
This article reports the measurement of the ionization quenching factor in germanium for nuclear recoil energies in the keV range. Precise knowledge of this factor in this energy range is highly relevant for coherent elastic neutrino-nucleus scattering and low mass dark matter searches with germanium-based detectors. Nuclear recoils were produced in a thin high-purity germanium target with a very low energy threshold via irradiation using monoenergetic neutron beams. The energy dependence of the ionization quenching factor was directly measured via kinematically constrained coincidences with surrounding liquid scintillator based neutron detectors. The systematic uncertainties of the measurements are discussed in detail. With measured quenching factors between 0.16 and 0.23 in the 0.4 keVnr to 6.3 keVnr energy range, the data are compatible with the Lindhard theory with a parameter k of 0.162 ±0.004 (stat + sys).
Journal Article
Loss of lamin A function increases chromatin dynamics in the nuclear interior
2015
Chromatin is organized in a highly ordered yet dynamic manner in the cell nucleus, but the principles governing this organization remain unclear. Similarly, it is unknown whether, and how, various proteins regulate chromatin motion and as a result influence nuclear organization. Here by studying the dynamics of different genomic regions in the nucleus of live cells, we show that the genome has highly constrained dynamics. Interestingly, depletion of lamin A strikingly alters genome dynamics, inducing a dramatic transition from slow anomalous diffusion to fast and normal diffusion. In contrast, depletion of LAP2α, a protein that interacts with lamin A and chromatin, has no such effect on genome dynamics. We speculate that chromosomal inter-chain interactions formed by lamin A throughout the nucleus contribute to chromatin dynamics, and suggest that the molecular regulation of chromatin diffusion by lamin A in the nuclear interior is critical for the maintenance of genome organization.
Nuclear lamins mediate interactions between chromatin and the nuclear envelope, however they are also found throughout the nucleoplasm. By measuring the dynamics of different genomic loci, Bronshtein
et al.
show that lamin A is also required for the stability of the nuclear interior.
Journal Article
First upper limits on neutrino electromagnetic properties from the CONUS experiment
2022
We report first constraints on electromagnetic properties of neutrinos from neutrino-electron scattering using data obtained from the CONUS germanium detectors, i.e. an upper limit on the effective neutrino magnetic moment and an upper limit on the effective neutrino millicharge. The electron antineutrinos are emitted from the 3.9 GWth reactor core of the Brokdorf Nuclear Power Plant in Germany. The CONUS low-background detectors are positioned at a distance of 17.1 m from the reactor core center. The analyzed data set includes 689.1 kg d collected during reactor ON periods and 131.0 kg d collected during reactor OFF periods in the energy range of . With the current statistics, we are able to determine an upper limit on the effective neutrino magnetic moment of μν<7.5·10-11μB at 90% confidence level. No neutrino signal in this channel or in the CEνNS channel has been observed at a nuclear power plant so far. From this first magnetic moment limit we can derive an upper bound on the neutrino millicharge of |qν|<3.3·10-12e0.
Journal Article
Neutron-induced background in the CONUS experiment
by
Fülber, K
,
Zbořil, M
,
Klages, T
in
Background radiation
,
Coherent scattering
,
Computer simulation
2019
CONUS is a novel experiment aiming at detecting elastic neutrino–nucleus scattering in the almost fully coherent regime using high-purity germanium (Ge) detectors and a reactor as antineutrino source. The detector setup is installed at the commercial nuclear power plant in Brokdorf, Germany, at a short distance to the reactor core to guarantee a high antineutrino flux. A good understanding of neutron-induced backgrounds is required, as the neutron recoil signals can mimic the predicted neutrino interactions. Especially events correlated with the reactor thermal power are troublesome. On-site measurements revealed such a correlated, highly thermalized neutron field with a maximum fluence rate of \\[(745\\pm 30)\\,\\hbox {cm}^{-2}\\,\\hbox {day}^{-1}\\]. These neutrons, produced inside the reactor core, are reduced by a factor of \\[\\sim 10^{20}\\] on their way to the CONUS shield. With a high-purity Ge detector without shield the \\[\\gamma \\]-ray background was examined including thermal power correlated \\[^{16}\\hbox {N}\\] decay products and neutron capture \\[\\gamma \\]-lines. Using the measured neutron spectrum as input, Monte Carlo simulations demonstrated that the thermal power correlated field is successfully mitigated by the CONUS shield. The reactor-induced background contribution in the region of interest is exceeded by the expected signal by at least one order of magnitude assuming a realistic ionization quenching factor.
Journal Article
National differences in gender-science stereotypes predict national sex differences in science and math achievement
2009
About 70% of more than half a million Implicit Association Tests completed by citizens of 34 countries revealed expected implicit stereotypes associating science with males more than with females. We discovered that nation-level implicit stereotypes predicted nation-level sex differences in 8th-grade science and mathematics achievement. Self-reported stereotypes did not provide additional predictive validity of the achievement gap. We suggest that implicit stereotypes and sex differences in science participation and performance are mutually reinforcing, contributing to the persistent gender gap in science engagement.
Journal Article
Full background decomposition of the CONUS experiment
2023
The CONUS experiment is searching for coherent elastic neutrino nucleus scattering of reactor anti-neutrinos with four low-energy threshold point-contact high-purity germanium spectrometers. Excellent background suppression within the region of interest below 1 keV (ionization energy) is absolutely necessary to enable signal detection. The collected data also make it possible to set limits on various models regarding beyond the standard model physics. These analyses benefit as well from the low background level of
∼
10 d
-
1
kg
-
1
below 1 keV and at higher energies. The low background level is achieved by employing a compact shell-like shield that was adapted to the most relevant background sources at the shallow depth location of the experiment: environmental gamma radiation and muon-induced secondaries. Overall, the compact CONUS shield including the active anticoincidence muon-veto reduces the background by more than four orders of magnitude. The remaining background is described with validated Monte Carlo simulations which include the detector response. It is the first time that a full background decomposition in germanium operated at a reactor site has been achieved. Next to the remaining muon-induced background,
210
Pb within the shield and cryostat end caps, cosmogenic activation and airborne radon are the most relevant background sources. The reactor-correlated background is negligible within the shield. The validated background model, together with the parameterization of the noise, is used as input to the likelihood analyses of the various physics cases.
Journal Article
The Devastating 2022 M6.2 Afghanistan Earthquake: Challenges, Processes, and Implications
2023
On June 21st, a Mw6.2 earthquake struck the Afghan‐Pakistan‐border‐region, situated within the India‐Asia collision. Thousand thirty‐nine deaths were reported, making the earthquake the deadliest of 2022. We investigate the event's rupture processes by combining seismological and geodetic observations, aiming to understand what made it that fatal. Our Interferometric Synthetic Aperture Radar‐constrained slip‐model and regional moment‐tensor inversion, confirmed through field observations, reveal a sinistral rupture with maximum slip of 1.8 m at 5 km depth on a N20°E striking, sub‐vertical fault. We suggest that not only external factors (event‐time, building stock) but fault‐specific factors made the event excessively destructive. Surface rupture was favored by the rock foliation, coinciding with the fault strike. The distribution of Peak‐Ground‐Velocity was governed by the sub‐vertical fault. Maximum slip was large compared to other events globally and might have resulted in peak‐frequencies coinciding with resonance‐frequencies of the local buildings and demonstrates the devastating impact of moderate‐size earthquakes. Plain Language Summary The June 2022 devastating M6.2 Afghanistan earthquake has caused a high depth toll, making it the deadliest earthquake of 2022. This is notable and partly intriguing as the earthquake size is much smaller than other events that happened in 2022. Therefore, we combine a range of geophysical, geodetic and geological methods to understand how exactly the subsurface ruptured during the earthquake. We suggest that it was a combination of the local circumstances (the event time, as it hit at night time, and the building stock) and the geometry of the rupture surface together with the local geology that made this event particularly deadly. More generally, this study shows the excessive hazard and impact caused by moderate‐size earthquakes. Key Points We combine Interferometric Synthetic Aperture Radar, moment tensor inversion, field mapping and Peak‐Ground‐Velocity (PGV) simulations to investigate the rupture processes The event had a sinistral rupture with maximum slip of 1.8 m at 5 km depth on a N20°E striking, sub‐vertical fault Coincidence of large slip, fault geometry and alignment of rock foliation with strike enhanced PGV and the destructiveness of the event
Journal Article
Improving electro-weak fits with TeV-scale sterile neutrinos
by
Michaels, L.
,
Kartavtsev, A.
,
Akhmedov, E.
in
Bosons
,
Classical and Quantum Gravitation
,
Decay
2013
A
bstract
We study the impact of TeV-scale sterile neutrinos on electro-weak precision observables and lepton number and flavour violating decays in the framework of a type-I see-saw extension of the Standard Model. At tree level sterile neutrinos manifest themselves via non-unitarity of the PMNS matrix and at one-loop level they modify the oblique radiative corrections. We derive explicit formulae for the
S, T, U
parameters in terms of the neutrino masses and mixings and perform a numerical fit to the electro-weak observables. We find regions of parameter space with a sizable active-sterile mixing which provide a better over-all fit compared to the case where the mixing is negligible. Specifically we find improvements of the invisible
Z
-decay width, the charged-to-neutral-current ratio for neutrino scattering experiments and of the deviation of the
W
boson mass from the theoretical expectation.
Journal Article