Search results for "nuclear physics"
showing 10 items of 5307 documents
Comparison between simulated and observed LHC beam backgrounds in the ATLAS experiment at E beam =4 TeV
2018
Results of dedicated Monte Carlo simulations of beam-induced background (BIB) in the ATLAS experiment at the Large Hadron Collider (LHC) are presented and compared with data recorded in 2012. During normal physics operation this background arises mainly from scattering of the 4 TeV protons on residual gas in the beam pipe. Methods of reconstructing the BIB signals in the ATLAS detector, developed and implemented in the simulation chain based on the FLUKA Monte Carlo simulation package, are described. The interaction rates are determined from the residual gas pressure distribution in the LHC ring in order to set an absolute scale on the predicted rates of BIB so that they can be compared qua…
New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the HIBEAM/NNBAR experiment at the European Spalla…
2021
Abstract The violation of baryon number, B , is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the Universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation Source to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron–antineutron oscillation ( n → n ̄ ) via mixing, neutron–antineutron oscillation via regeneration from a sterile neutron state ( n → [ n ′ , n ̄ ′ ] → n ̄ ), and neutron disappearan…
Lifetime measurement of neutron-rich even-even molybdenum isotopes
2017
D. Ralet et al. -- 11 pags., 10 figs., 3 tabs.
The detection efficiency of the clover Ge-detectors array at the RITU-GREAT facility
2015
Absolute detection efficiency depending upon its position along the beam line is determined for three germanium detectors, that are part of the GREAT spectrometer at the RITU separator focal plane. The efficiency is determined for an energy range from 80 keV to 1400 keV for all three detectors as an array and also individually using digital electronics. The optimal position for the detector array has been defined for two configurations of the GREAT spectrometer: with planar detector and without it. The obtained results have been compared with three references: a simulation prepared especially for this setup by another student, a previous study that was carried out by applying analogue elect…
Target Cooling Options for Neutron Sources at High Power Densities
2014
Abstract Compact neutron sources in many cases beat large ones when it comes to power density; thus, many issues concerning cooling are shared, and each party can learn a lot from the other facilities. Starting from accrued experience with water cooling at moderate power densities in SINQ over the last 15 years, a brief overview will be attempted showing the relevant parameters and specific approaches at several existing and planned neutron (spallation) sources. Extensions from the established ground of cooling with water will be sketched in two directions. An outline of an experiment planned for freshly determining in a representative geometry the hard limit for water cooling, i.e. full bo…
The effective cross section for double parton scattering within a holographic AdS/QCD approach
2017
A first attempt to apply the AdS/QCD framework for a bottom-up approach to the evaluation of the effective cross section for double parton scattering in proton-proton collisions is presented. The main goal is the analytic evaluation of the dependence of the effective cross section on the longitudinal momenta of the involved partons, obtained within the holographic Soft-Wall model. If measured in high-energy processes at hadron colliders, this momentum dependence could open a new window on 2-parton correlations in a proton.
Physics reach of the XENON1T dark matter experiment.
2016
The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in $1$ tonne fiducial volume and ($1$, $12$) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is $(1.80 \pm 0.15) \cdot 10^{-4}$ ($\rm{kg} \cdot day \cdot keV)^{-1}$, mainly due to the decay of $^{222}\rm{Rn}$ daughters inside the xenon target. The nu…
Intrinsic backgrounds from Rn and Kr in the XENON100 experiment
2018
In this paper, we describe the XENON100 data analyses used to assess the target-intrinsic background sources radon ([InlineMediaObject not available: see fulltext.]), thoron ([InlineMediaObject not available: see fulltext.]) and krypton ([InlineMediaObject not available: see fulltext.]). We detail the event selections of high-energy alpha particles and decay-specific delayed coincidences. We derive distributions of the individual radionuclides inside the detector and quantify their abundances during the main three science runs of the experiment over a period of ∼4years, from January 2010 to January 2014. We compare our results to external measurements of radon emanation and krypton concentr…
First Accurate Normalization of the $\beta$-delayed $\alpha$ Decay of $^{16}$N and Implications for the $^{12}$C$(\alpha,\gamma)^{16}$O Astrophysical…
2018
The $^{12}\text{C}(\alpha,\gamma){}^{16}\text{O}$ reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced $\alpha$ width, $\gamma_{11}$, of the bound $1^-$ level in $^{16}$O is particularly important to determine the cross section. The magnitude of $\gamma_{11}$ is determined via sub-Coulomb $\alpha$-transfer reactions or the $\beta$-delayed $\alpha$ decay of $^{16}$N, but the latter approach is presently hampered by the lack of sufficiently precise data on the $\beta$-decay branching ratios. Here we report improved branching ratios for the bound $1^-$ level [$b_{\beta…
Measurements of the top quark branching ratios into channels with leptons and quarks with the ATLAS detector
2015
Measurements of the branching ratios of top quark decays into leptons and jets using events with t[bar over t] (top antitop) pairs are reported. Events were recorded with the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of 7 TeV. The collected data sample corresponds to an integrated luminosity of 4.6 fb[superscript −1]. The measured top quark branching ratios agree with the Standard Model predictions within the measurement uncertainties of a few percent.