Tue·Apr 4, 2017Tuesday·April 4, 2017

1. 01*

   Evaluating $V_{ud}$ from neutron beta decays

   Dinko Pocanic🇺🇸

   Although well studied, the neutron still offers a unique laboratory for precise tests of Standard Model (SM) predictions. Neutron decay is free of nuclear structure corrections present in nuclear beta decays, and, with a $10^8$ times larger branching ratio than the theoretically cleaner pion beta decay, it is more readily accessible to experimental study than the latter. Measurements at sufficient precision of the neutron lifetime, and of correlations in free neutron beta decay, offer several stringent tests of the SM, including the weak quark couplings (quark-lepton universality), and certain extensions beyond the standard $V-A$ weak interaction theory. This paper focuses on the long-running free neutron beta decay experimental program aimed at obtaining an independent determination of the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix element $V_{ud}$. We discuss the present state of precision achieved in this program and briefly review the currently active projects, as well as the expected near-term improvements in the field.

   nucl-exhep-phPoS(2017)·2 citations
2. 02*

   J/$\psi$ production as a function of charged-particle pseudorapidity density in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   We report measurements of the inclusive J/$\psi$ yield and average transverse momentum as a function of charged-particle pseudorapidity density $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ALICE at the LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/$\psi$ yield with normalised $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta$, measured at mid-rapidity, is observed at mid-rapidity and backward rapidity. At forward rapidity, a saturation of the relative yield is observed for high charged-particle multiplicities. The normalised average transverse momentum at forward and backward rapidities increases with multiplicity at low multiplicities and saturates beyond moderate multiplicities. In addition, the forward-to-backward nuclear modification factor ratio is also reported, showing an increasing suppression of J/$\psi$ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.

   nucl-exhep-exPLB(2018)·55 citations
3. 03*

   $W$ and $Z$ boson production in 5.02 TeV $pp$ and $p$+Pb collisions with the ATLAS detector

   Mirta Dumančić🇮🇱

   This proceeding reports the ATLAS results of measuring vector boson production in $pp$ and $p$+Pb collisions at the center-of-mass energy of 5.02~TeV per nucleon. $Z$ boson bosons are reconstructed via leptonic decays and results are presented as a function of $Z$-boson rapidity. $W$ boson bosons are identified by measuring leptons coming from $W$ boson decays and the results are presented as a function of lepton pseudorapidity. In $pp$ collisions $Z$ boson boson cross section in $|y_Z|<2.5$ is 590$\pm$9 (stat.)$\pm$12 (syst.)$\pm$32 (lumi.) pb. In $p$+Pb system kinematic distributions of $W$ boson and $Z$ boson bosons are compared to models based on NLO and NNLO QCD calculations using different PDF sets. Using PDF modification shows better agreement of the model and the data. Measurements done in different centrality intervals show that the PDF modification in $p$+Pb may have centrality dependence.

   nucl-exNucl.Part.Phys.Proc.(2017)·0 citations
4. 04*

   Proton Cumulants and Correlation Functions in Au + Au Collisions at $\sqrt{s_{\mathrm{NN}}}$=7.7-200 GeV from UrQMD Model

   Shu He🇨🇳 · Xiaofeng Luo🇨🇳

   We studied the acceptance dependence of proton cumulants (up to fourth order) and correlation functions in 0--5\% most central Au+Au collisions at $\sqrt{s_{\text{NN}}}$=7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV from UrQMD model. We found that high order proton cumulants show suppressions at large acceptance. By decomposing the proton cumulants into linear combination of multi-proton correlation functions, we observed the two-proton correlation functions always show negative values due to the effects of baryon number conservations. The three and four-proton correlation functions are close to zero and show negligible acceptance dependence. We further observed that the proton cumulants and correlation functions follow similar trends and show a scaling behavior when plotting the results versus mean number of protons. The comparisons between experimental data and the UrQMD calculations show that the non-monotonic energy dependence of proton correlation functions measured by STAR experiment cannot be described by the UrQMD model. The UrQMD calculations can provide us baselines for the experimental studies of the proton cumulants and correlation functions. Finally, we propose to measure the rapidity dependence of the reduced proton correlation functions to search for the QCD critical point in heavy-ion collisions.

   nucl-exhep-exhep-phnucl-thPLB(2017)·38 citations
5. 05*

   Study of the $\beta$-decay of ${}^{100}$Tc with Total Absorption $\gamma$-Ray Spectroscopy

   V. Guadilla🇪🇸 · A. Algora🇪🇸 · J.L. Tain🇪🇸 · J. Agramunt🇪🇸 · D. Jordan🇪🇸 · A. Montaner-Pizá🇪🇸 · S.E.A. Orrigo🇪🇸 · B. Rubio🇪🇸 · E. Valencia🇪🇸 · J. Suhonen🇫🇮 · O. Civitarese🇦🇷 · J. Äystö🇫🇮 and 33 other authors

   The \b{eta}-decay of 100 Tc has been studied using the Total Absorption {\gamma}-Ray Spectroscopy technique at IGISOL. In this work the new DTAS spectrometer in coincidence with a cylindrical plastic \b{eta} detector has been employed. The \b{eta}-intensity to the ground state obtained from the analysis is in good agreement with previous high-resolution measurements. However, differences in the feeding to the first excited state as well as weak feeding to a new level at high excitation energy have been deduced from this experiment. Theoretical calculations performed in the quasiparticle random- phase approximation (QRPA) framework are also reported. Comparison of these calculations with our measurement serves as a benchmark for calculations of the double \b{eta}-decay of 100 Mo.

   nucl-exPRC(2017)·24 citations
6. 06*

   Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E

   L. Witthauer🇨🇭 · M. Dieterle🇨🇭 · F. Afzal🇩🇪 · A.V. Anisovich🇩🇪 · B. Bantes🇩🇪 · D. Bayadilov🇩🇪 · R. Beck🇩🇪 · M. Bichow🇩🇪 · K.-T. Brinkmann🇩🇪 · S. Böse🇩🇪 · Th. Challand🇨🇭 · V. Crede🇺🇸 and 61 other authors

   Photoproduction of $\eta$ mesons from neutrons} \abstract{Results from measurements of the photoproduction of $\eta$ mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the $\eta \to 3{\pi }^0\to 6\gamma$ decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of $\gamma n\to n\eta$. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow $P_{11}$ state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable $E$. Both data sets together were also used to extract the helicity dependent cross sections ${\sigma }_{1/2}$ and ${\sigma }_{3/2}$. The narrow structure in the excitation function of $\gamma n\to n\eta$ appears associated with the helicity-1/2 component of the reaction.

   nucl-exEPJA(2017)·24 citations
7. 07*

   Helicity-dependent cross sections and double-polarization observable E in eta photoproduction from quasi-free protons and neutrons

   L. Witthauer🇨🇭 · M. Dieterle🇨🇭 · S. Abt🇨🇭 · P. Achenbach🇩🇪 · F. Afzal🇩🇪 · Z. Ahmed🇨🇦 · C.S. Akondi🇺🇸 · J.R.M. Annand🇬🇧 · H.J. Arends🇩🇪 · M. Bashkanov🇬🇧 · R. Beck🇩🇪 · M. Biroth🇩🇪 and 75 other authors

   Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta \to 2\gamma$ and $\eta \to 3{\pi }^0\to 6\gamma$ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. A longitudinally polarized deuterated butanol target was used in combination with a circularly polarized photon beam from bremsstrahlung of a longitudinally polarized electron beam. The reaction products were detected with the electromagnetic calorimeters Crystal Ball and TAPS, which covered 98\% of the full solid angle. The results show that the narrow structure observed earlier in the unpolarized excitation function of $\eta$ photoproduction off the neutron appears only in reactions with antiparallel photon and nucleon spin (${\sigma }_{1/2}$). It is absent for reactions with parallel spin orientation (${\sigma }_{3/2}$) and thus very probably related to partial waves with total spin 1/2. The behavior of the angular distributions of the helicity-dependent cross sections was analyzed by fitting them with Legendre polynomials. The results are in good agreement with a model from the Bonn-Gatchina group, which uses an interference of $P_{11}$ and $S_{11}$ partial waves to explain the narrow structure.

   nucl-exPRC(2017)·33 citations
8. 08*

   Experimental Observations of Nuclear Activity in Deuterated Materials Subjected to a Low-Energy Photon Beam

   Bruce M. Steinetz · Theresa L. Benyo (National Aeronautics and Space Administration, Glenn Research Center) · Vladimir Pines · Marianna Pines (PineSci Consulting) · Lawrence P. Forsley (JWK Corporation) · Paul A. Westmeyer (National Aeronautics and Space Administration, Headquarters) · Arnon Chait (National Aeronautics and Space Administration, Glenn Research Center) · Michael D. Becks (Vantage Partners, LLC) · Richard E. Martin (Cleveland State University) · Robert C. Hendricks (National Aeronautics and Space Administration, Glenn Research Center) · Nicholas Penney (Ohio Aerospace Institute) · Annette M. Marsolais · Tracy R. Kamm (Vantage Partners, LLC)

   Exposure of highly deuterated materials to a low-energy (nom. 2 MeV) photon beam resulted in nuclear activity of both the parent metals of hafnium and erbium and a witness material (molybdenum) mixed with the reactants. Gamma spectral analysis of all deuterated materials, ErD2.8-C36D74-Mo and HfD2-C36D74-Mo, showed that nuclear processes had occurred as shown by unique gamma signatures. For the deuterated erbium specimens, posttest gamma spectra showed evidence of radioisotopes of erbium (163Er and 171Er) and of molybdenum (99Mo and 101Mo) and by beta decay, technetium (99mTc and 101Tc). For the deuterated hafnium specimens, posttest gamma spectra showed evidence of radioisotopes of hafnium (180mHf and 181Hf) and molybdenum (99Mo and 101Mo), and by beta decay, technetium (99mTc and 101Tc). In contrast, when either the hydrogenated or non-gas-loaded erbium or hafnium materials were exposed to the gamma flux, the gamma spectra revealed no new isotopes. Neutron activation materials showed evidence of thermal and epithermal neutrons. CR-39 solid-state nuclear track detectors showed evidence of fast neutrons with energies between 1.4 and 2.5 MeV and several instances of triple tracks, indicating greater than 10 MeV neutrons. Further study is required to determine the mechanism causing the nuclear activity

   nucl-exphysics.ins-det1 citation
9. 09*

   Experimental constraint on quark electric dipole moments

   Tianbo Liu🇺🇸 · Zhiwen Zhao🇺🇸 · Haiyan Gao🇺🇸

   The electric dipole moments (EDMs) of nucleons are sensitive probes of additional $\mathcal{C}\mathcal{P}$ violation sources beyond the standard model to account for the baryon number asymmetry of the universe. As a fundamental quantity of the nucleon structure, tensor charge is also a bridge that relates nucleon EDMs to quark EDMs. With a combination of nucleon EDM measurements and tensor charge extractions, we investigate the experimental constraint on quark EDMs, and its sensitivity to $\mathcal{C}\mathcal{P}$ violation sources from new physics beyond the electroweak scale. We obtain the current limits on quark EDMs as $1.27\times 10^{-24}e\cdot \mathrm{cm}$ for the up quark and $1.17\times 10^{-24}e\cdot \mathrm{cm}$ for the down quark at the scale of $4\mathrm{Ge}{\mathrm{V}}^2$. We also study the impact of future nucleon EDM and tensor charge measurements, and show that upcoming new experiments will improve the constraint on quark EDMs by about three orders of magnitude leading to a much more sensitive probe of new physics models.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2018)·42 citations
10. 10*

    The Cross Section Calculation of the ${}^{112}$Sn($\alpha$,$\gamma$)${}^{116}$Te Reaction with Different Nuclear Models at the Astrophysical Energy Range

    C. Yalcin

    The theoretical cross section calculations for the astrophysical $p$ process are needed because the most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured, most of the measured reactions have been carried out at the higher energy range from the astrophysical energies. Therefore, almost all cross sections needed for $p$ process simulation has to be theoretically calculated or extrapolated to the astrophysical energies. The ${}^{112}$Sn($\alpha$,$\gamma$)${}^{116}$Te is an important reaction for the $p$ process nucleosynthesis. The theoretical cross section of the ${}^{112}$Sn($\alpha$,$\gamma$)${}^{116}$Te reaction was investigated for different global optical model potentials, level density and strength function models at the astrophysically interested energies. Astrophysical $S$ factors were calculated and compared with experimental data available in EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and Back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the $p$ process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.

    ↳ nucl-thastro-ph.HEnucl-exNucl.Sci.Tech.(2017)·6 citations
11. 11*

    Investigation of Deuterium Loaded Materials Subject to X-Ray Exposure

    Theresa L. Benyo · Bruce M. Steinetz · Robert C. Hendricks (National Aeronautics and Space Administration, Glenn Research Center) · Richard E. Martin (Cleveland State University) · Lawrence P. Forsley (JWK Corporation) · Christopher C. Daniels (The University of Akron) · Arnon Chait (National Aeronautics and Space Administration, Glenn Research Center) · Vladimir Pines · Marianna Pines (PineSci Consulting) · Nicholas Penney (Ohio Aerospace Institute) · Tracy R. Kamm · Michael D. Becks (Vantage Partners, LLC)

    Results are presented from an exploratory study involving x-ray irradiation of select deuterated materials. Titanium deuteride (TiD2) plus deuterated polyethylene ([-CD2-]n; DPE), DPE alone, and for control, hydrogen-based polyethylene ([-CH2-]n; HPE) samples and nondeuterated titanium samples were exposed to x-ray irradiation. These samples were exposed to various energy levels from 65 to 280 kV with prescribed electron flux from 500 to 9000 micro-A impinging on a tungsten braking target, with total exposure times ranging from 55 to 280 min. Gamma activity was measured using a high-purity germanium (HPGe) detector, and for all samples no gamma activity above background was detected. Alpha and beta activities were measured using a gas proportional counter, and for select samples beta activity was measured with a liquid scintillator spectrometer. The majority of the deuterated materials subjected to the microfocus x-ray irradiation exhibited postexposure beta activity above background and several showed short-lived alpha activity. The HPE and nondeuterated titanium control samples exposed to the x-ray irradiation showed no postexposure alpha or beta activities above background. Several of the samples (SL10A, SL16, SL17A) showed beta activity above background with a greater than 4-sigma confidence level, months after exposure. Portions of SL10A, SL16, and SL17A samples were also scanned using a beta scintillator and found to have beta activity in the tritium energy band, continuing without noticeable decay for over 12 months. Beta scintillation investigation of as-received materials (before x-ray exposure) showed no beta activity in the tritium energy band, indicating the beta emitters were not in the starting materials.

    ↳ physics.ins-detnucl-ex0 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.