Mon·Aug 26, 2019Monday·August 26, 2019

1. 01*

   Background in $\gamma$-ray detectors and carbon beam tests in the Felsenkeller shallow-underground accelerator laboratory

   T. Szücs🇩🇪 · D. Bemmerer🇩🇪 · D. Degering🇩🇪 · A. Domula🇩🇪 · M. Grieger🇩🇪 · F. Ludwig🇩🇪 · K. Schmidt🇩🇪 · J. Steckling🇩🇪 · S. Turkat🇩🇪 · K. Zuber🇩🇪

   The relevant interaction energies for astrophysical radiative capture reactions are very low, much below the repulsive Coulomb barrier. This leads to low cross sections, low counting rates in $\gamma$-ray detectors, and therefore the need to perform such experiments at ion accelerators placed in underground settings, shielded from cosmic rays. Here, the feasibility of such experiments in the new shallow-underground accelerator laboratory in tunnels VIII and IX of the Felsenkeller site in Dresden, Germany, is evaluated. To this end, the no-beam background in three different types of germanium detectors, i.e. a Euroball/Miniball triple cluster and two large monolithic detectors, is measured over periods of 26-66 days. The cosmic-ray induced background is found to be reduced by a factor of 500-2400, by the combined effects of, first, the 140 meters water equivalent overburden attenuating the cosmic muon flux by a factor of 40, and second, scintillation veto detectors gating out most of the remaining muon-induced effects. The new background data are compared to spectra taken with the same detectors at the Earth's surface and at other underground sites. Subsequently, the beam intensity from the cesium sputter ion source installed in Felsenkeller has been studied over periods of several hours. Based on the background and beam intensity data reported here, for the example of the ${}^{12}$C($\alpha$,$\gamma$)${}^{16}$O reaction it is shown that highly sensitive experiments will be possible.

   nucl-exphysics.ins-detEPJA(2019)·20 citations
2. 02*

   Neutral Current Neutrino-Nucleus Scattering. Theory

   Carlotta Giusti🇮🇹 · Martin V. Ivanov🇧🇬

   The treatment of nuclear effects in neutrino-nucleus interactions is one of the main sources of systematic uncertainty for the analysis and interpretation of data of neutrino oscillation experiments. Neutrinos interact with nuclei via charged or neutral currents and both cases must be studied to obtain a complete information. We give an overview of the theoretical work that has been done to describe nuclear effects in neutral-current neutrin onucleus scattering in the kinematic region ranging between beam energies of a few hundreds MeV to a few GeV, which is typical of most ongoing and future accelerator-based neutrino experiments, and where quasielastic scattering is the main interaction mechanism. We review the current status and challenges of the theoretical models, the role and relevance of the contributions of different nuclear effects, and the present status of the comparison between the numerical predictions of the models as well as the available experimental data. We discuss also the sensitivity to the strange form factors of the nucleon and the methods and observables that can allow one to obtain evidence for a possible strange quark contribution from measurements of neutrino and antineutrino-nucleus scattering.

   ↳ hep-phnucl-exnucl-thJ.Phys.G(2020)·18 citations
3. 03*

   Studies of helium poisoning of a Hamamatsu R5900-00-M16 photomultiplier

   Rustem Ospanov🇺🇸 · Michael Kordosky🇺🇸 · Karol Lang🇺🇸 · Jing Liu🇺🇸 · Thomas Osiecki🇺🇸 · Marek Proga🇺🇸 · Patricia Vahle🇺🇸

   We report results from studies of the helium poisoning of a 16-anode photomultiplier tube R5900-00-M16 manufactured by Hamamatsu Photonics. A tube was immersed in pure helium for a period of about four months and was periodically monitored using a digital oscilloscope. Our results are based on the analysis of waveforms triggered by the dark noise pulses. Collected data yield evidence of after-pulses due to helium contamination of the tube. The probability of after-pulsing increased linearly with the exposure time to helium but the phototube suffered only a small drop in gain, indicating generally strong resilience to helium poisoning.

   ↳ physics.ins-dethep-exnucl-ex2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.