The impurity density in high-purity germanium detectors is crucial to understand and simulate such detectors. However, the information about the impurities provided by the manufacturer, based on Hall ...effect measurements, is typically limited to a few locations and comes with a large uncertainty. As the voltage dependence of the capacitance matrix of a detector strongly depends on the impurity density distribution, capacitance measurements can provide a path to improve the knowledge on the impurities. The novel method presented here uses a machine-learned surrogate model, trained on precise GPU-accelerated capacitance calculations, to perform full Bayesian inference of impurity distribution parameters from capacitance measurements. All steps use open-source Julia software packages. Capacitances are calculated with
SolidStateDetectors.jl
, machine learning is done with
Flux.jl
and Bayesian inference performed using
BAT.jl
. The capacitance matrix of a detector and its dependence on the impurity density is explained and a capacitance bias-voltage scan of an
n
-type true-coaxial test detector is presented. The study indicates that the impurity density of the test detector also has a radial dependence.
Events from alpha interactions on the surfaces of germanium detectors are a major contribution to the background in germanium-based searches for neutrinoless double-beta decay. Surface events are ...subject to charge trapping, affecting their pulse shape and reconstructed energy. A study of alpha events on the passivated end-plate of a segmented true-coaxial n-type high-purity germanium detector is presented. Charge trapping is analysed in detail and an existing pulse-shape analysis technique to identify alpha events is verified with mirror pulses observed in the non-collecting channels of the segmented test detector. The observed radial dependence of charge trapping confirms previous results. A dependence of the probability of charge trapping on the crystal axes is observed for the first time. A first model to describe charge trapping effects within the framework of the simulation software
SolidStateDetectors.jl
is introduced. The influence of metalisation on events from low-energy gamma interactions close to the passivated surface is also presented.
A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering has been performed. The data are presented and investigated for a kinematic range extending from values ...of the four-momentum transfer, Q2, above 104 GeV2 down to the lowest values observable at HERA of Q2=0.045 GeV2 and Bjorken x, xBj=6×10−7. The data are well described by fits based on perturbative quantum chromodynamics (QCD) using collinear factorisation and evolution of the parton densities encompassed in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi formalism from the highest Q2 down to Q2 of a few GeV2. The Regge formalism with the soft Pomeron pole can describe the data up to Q2≈0.65 GeV2. The complete data set can be described by a new fit using the Abramowicz-Levin-Levy-Maor parametrization. The region between the Regge and the perturbative QCD regimes is of particular interest.
For the first time, planar high-purity germanium detectors with thin amorphous germanium contacts were successfully operated directly in liquid nitrogen and liquid argon in a cryostat at the ...Max-Planck-Institut für Physics in Munich. The detectors were fabricated at the Lawrence Berkeley National Laboratory and the University of South Dakota, using crystals grown at the University of South Dakota. They survived long-distance transportation and multiple thermal cycles in both cryogenic liquids and showed reasonable leakage currents and spectroscopic performance. Also discussed are the pros and cons of using thin amorphous semiconductor materials as an alternative contact technology in large-scale germanium experiments searching for physics beyond the Standard Model.
The wheat dwarf disease is among the most damaging diseases in cereals. Its aetiological agent is the Wheat dwarf virus (WDV), which is exclusively transmitted from plant to plant by leafhoppers from ...the genus Psammotettix (Hemiptera, Cicadellidae). The parameters linked to the WDV/Psammotettix pathosystem are still poorly understood. We studied Psammotettix individuals collected in wheat and barley fields in France and, as a comparison, from grassland at agroecological interface in West Slovenia. Species identity of males and females has been determined using multiple criteria. In the first step, the characterization of the collected individuals included recordings of vibrational signals used in mating behaviour and morphometric analyses. In addition, a 442 nt sequence of the mitochondrial cytochrome oxydase I (COI) gene was obtained for some individuals and compared to COI sequences of the Psammotettix leafhoppers available in public databases. In the cereal fields in France, P sammotettix alienus was the most numerous species; however, it sometimes occurred together with Psammotettix confinis, while in the grasslands in Slovenia, the third syntopic species in Psammotettix community was Psammotettix helvolus. The temporal parameters of the P. alienus male calling song that were measured in this study were very similar to those measured in a previous study. The local biotic and/or abiotic parameters most likely influence the life history of Psammotettix leafhoppers, and the proportion of viruliferous individuals collected in cereal fields was 14.9%, while leafhoppers collected in Slovenia were virus-free. Taken together, results show that more detailed information on population structure of Psammotettix leafhoppers is crucial for providing an insight into the epidemiology of wheat dwarf disease.
A simultaneous electroweak and QCD fit of electroweak parameters and parton distribution functions to HERA data on deep inelastic scattering is presented. The input data are neutral current and ...charged current inclusive cross sections measured by the H1 and ZEUS collaborations at the ep collider HERA. The polarization of the electron beam was taken into account for the ZEUS and H1 data recorded between 2004 and 2007. Results are presented on the vector and axial-vector couplings of the Z boson to u- and d-type quarks. The values are in agreement with Standard Model predictions. The results on au and vu represent the most precise measurements from a single process.
Combined HERA data on charm production in deep-inelastic scattering have previously been used to determine the charm-quark running mass mc(mc) in the MS‾ renormalisation scheme. Here, the same data ...are used as a function of the photon virtuality Q2 to evaluate the charm-quark running mass at different scales to one-loop order, in the context of a next-to-leading order QCD analysis. The scale dependence of the mass is found to be consistent with QCD expectations.