Mon·Sep 8, 2014Monday·September 8, 2014

1. 01*

   In Medium Nucleon Structure Functions, SRC, and the EMC effect

   O. Hen🇮🇱 · L.B. Weinstein🇺🇸 · S. Gilad🇺🇸 · S. A. Wood🇺🇸

   A proposal approved by the Jefferson Lab PAC to study semi-inclusive deep inelastic scattering (DIS) off the deuteron, tagged with high momentum recoiling protons or neutrons emitted at large angle relative to the momentum transfer. This experiment aims at studying the virtuality dependence of the bound nucleon structure function as a possible cause to the EMC effect and the EMC-SRC correlations. The experiment was approved in 2011 for a total run time of 40 days.

   nucl-exnucl-th12 citations
2. 02*

   Alpha-spectroscopy of Cf-252 decays: A new approach to searching for the octoneutron

   Hrant Gulkanyan🇦🇲 · Amur Margaryan🇦🇲

   Recently an experimental evidence of emission of neutron clusters consisting of eight neutrons - octoneutrons was reported. The experiment was based on the search for daughter nuclei associated with the octoneutron radioactivity of the Cf-252 nucleus. The effect of long-time build-up of daughter nuclei with a long half-life and gamma spectroscopy was utilized. In this paper we consider the alpha spectroscopy as an alternative method of searching for octoneutron in Cf-252 decays.

   nucl-ex0 citations
3. 03*

   Measurement of the $\beta$-asymmetry parameter of ${}^{67}$Cu in search for tensor type currents in the weak interaction

   G. Soti🇧🇪 · F. Wauters🇧🇪 · M. Breitenfeldt🇧🇪 · P. Finlay🇧🇪 · P. Herzog🇩🇪 · A. Knecht🇧🇪 · U. Köster🇫🇷 · I. S. Kraev🇧🇪 · T. Porobic🇧🇪 · P. N. Prashanth🇧🇪 · I. S. Towner🇺🇸 · C. Tramm🇩🇪 · D. Zákoucký🇨🇿 · N. Severijns🇧🇪

   Precision measurements at low energy search for physics beyond the Standard Model in a way complementary to searches for new particles at colliders. In the weak sector the most general $\beta$ decay Hamiltonian contains, besides vector and axial-vector terms, also scalar, tensor and pseudoscalar terms. Current limits on the scalar and tensor coupling constants from neutron and nuclear $\beta$ decay are on the level of several percent. The goal of this paper is extracting new information on tensor coupling constants by measuring the $\beta$-asymmetry parameter in the pure Gamow-Teller decay of ${}^{67}$Cu, thereby testing the V-A structure of the weak interaction. An iron sample foil into which the radioactive nuclei were implanted was cooled down to milliKelvin temperatures in a ${}^3$He-${}^4$He dilution refrigerator. An external magnetic field of 0.1 T, in combination with the internal hyperfine magnetic field, oriented the nuclei. The anisotropic $\beta$ radiation was observed with planar high purity germanium detectors operating at a temperature of about 10\,K. An on-line measurement of the $\beta$ asymmetry of ${}^{68}$Cu was performed as well for normalization purposes. Systematic effects were investigated using Geant4 simulations. The experimental value, $\tilde{A}$ = 0.587(14), is in agreement with the Standard Model value of 0.5991(2) and is interpreted in terms of physics beyond the Standard Model. The limits obtained on possible tensor type charged currents in the weak interaction hamiltonian are -0.045 $<(C_T+C_T^{\prime })/C_A<$ 0.159 (90\% C.L.). The obtained limits are comparable to limits from other correlation measurements in nuclear $\beta$ decay and contribute to further constraining tensor coupling constants.

   nucl-exPRC(2014)·20 citations
4. 04*

   Theory Viewpoint on Extracting Nucleon Polarisabilities in Low-Energy Compton Scattering

   Harald W. Griesshammer (George Washington U.)🇺🇸 · Anatoly I. L'vov (Lebedev Physical Institute)🇷🇺 · Judith A. McGovern (U. of Manchester)🇬🇧 · Vladimir Pascalutsa (U. Mainz)🇩🇪 · Barbara Pasquini (U. of Pavia)🇮🇹 · Daniel R. Phillips (Ohio U.)🇺🇸

   During the workshop "Compton Scattering off Protons and Light Nuclei: pinning down the nucleon polarisabilities" (ECT*, Trento, Italy, 29 July -- 2 August 2013, http://www.ectstar.eu/node/98), recent developments had been reviewed in experimental and theoretical studies of real and virtual Compton scattering, static and generalized dipole scalar and spin polarisabilities of nucleons, as well as related phenomena in physics of muonic atoms. A vivid topic at the workshop was pathways towards the most precise extraction of the static polarisabilities from low-energy Compton cattering---including pertinent theoretical uncertainties. Being asked by our experimental colleagues, we prepared during the workshop a short letter with conclusions of the discussion, emphasising future prospects.

   ↳ nucl-thhep-phnucl-ex6 citations
5. 05*

   eRHIC Design Study: An Electron-Ion Collider at BNL

   E.C. Aschenauer (BNL)🇺🇸 · M.D. Baker (BNL)🇺🇸 · A. Bazilevsky (BNL)🇺🇸 · K. Boyle (RBRC)🇺🇸 · S. Belomestnykh (BNL)🇺🇸 · I. Ben-Zvi (BNL)🇺🇸 · S. J. Brooks (BNL)🇺🇸 · C. Brutus (BNL)🇺🇸 · T. Burton (BNL)🇺🇸 · S. Fazio (BNL)🇺🇸 · A. Fedotov (BNL)🇺🇸 · D. Gassner (BNL)🇺🇸 and 35 other authors

   This document presents BNL's plan for an electron-ion collider, eRHIC, a major new research tool that builds on the existing RHIC facility to advance the long-term vision for Nuclear Physics to discover and understand the emergent phenomena of Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction that binds the atomic nucleus. We describe the scientific requirements for such a facility, following up on the community-wide 2012 white paper, 'Electron-Ion Collider: the Next QCD Frontier', and present a design concept that incorporates new, innovative accelerator techniques to provide a cost-effective upgrade of RHIC with polarized electron beams colliding with the full array of RHIC hadron beams. The new facility will deliver electron-nucleon luminosity of 10^33-10^34 cm-1sec-1 for collisions of 15.9 GeV polarized electrons on either 250 GeV polarized protons or 100 GeV/u heavy ion beams. The facility will also be capable of providing an electron beam energy of 21.2 GeV, at reduced luminosity. We discuss the on-going R&D effort to realize the project, and present key detector requirements and design ideas for an experimental program capable of making the 'golden measurements' called for in the EIC White Paper.

   ↳ physics.acc-phnucl-exphysics.ins-det181 citations
6. 06*

   The study of neutron spectra in water bath from Pb target irradiated by 250MeV/u protons

   Yanyan Li · Xueying Zhang · Yongqin Ju · Fei Ma · Hongbin Zhang · Liang Chen · Honglin Ge · Peng Luo · Bin Zhou · Yanbin Zhang · Jianyang Li · Junkui Xu and 3 other authors

   The spallation neutrons were produced by the irradiation of Pb with 250 MeV protons. The Pb target was surrounded by water which was used to slow down the emitted neutrons. The moderated neutrons in the water bath were measured by using the resonance detectors of Au, Mn and In with Cd cover. According to the measured activities of the foils, the neutron flux at different resonance energy were deduced and the epithermal neutron spectra were proposed. Corresponding results calculated with the Monte Carlo code MCNPX were compared with the experimental data to check the validity of the code.

   ↳ physics.ins-detnucl-exCPC(2015)·0 citations
7. 07*

   Photoelectric disintegration of 16O

   M. Katsuma

   The photoelectric cross section of ${}^{16}$O($\gamma$,$\alpha$)${}^{12}$C is estimated to be larger than the radiative capture cross section of ${}^{12}$C($\alpha$ ,$\gamma$)${}^{16}$O. The predicted cross section and the angular distribution of $\alpha$-particle are illustrated for the future experiment. The cross section just above the $\alpha$-particle threshold is found to be dominated by the $E$2 excitation.

   ↳ nucl-thnucl-exPRC(2014)·7 citations
8. 08*

   Measurement of long-range pseudorapidity correlations and azimuthal harmonics in $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV proton-lead collisions with the ATLAS detector

   ATLAS Collaboration

   Measurements of two-particle correlation functions and the first five azimuthal harmonics, $v_1$ to $v_5$, are presented, using 28 ${\mathrm{nb}}^{-1}$ of $p$+Pb collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV measured with the ATLAS detector at the LHC. Significant long-range ``ridge-like'' correlations are observed for pairs with small relative azimuthal angle ($|\Delta \varphi |<\pi /3$) and back-to-back pairs ($|\Delta \varphi |>2\pi /3$) over the transverse momentum range $0.4<p_{\mathrm{T}}<12$ GeV and in different intervals of event activity. The event activity is defined by either the number of reconstructed tracks or the total transverse energy on the Pb-fragmentation side. The azimuthal structure of such long-range correlations is Fourier decomposed to obtain the harmonics $v_n$ as a function of $p_{\mathrm{T}}$ and event activity. The extracted $v_n$ values for $n=2$ to $5$ decrease with $n$. The $v_2$ and $v_3$ values are found to be positive in the measured $p_{\mathrm{T}}$ range. The $v_1$ is also measured as a function of $p_{\mathrm{T}}$ and is observed to change sign around $p_{\mathrm{T}}\approx 1.5-2.0$ GeV and then increase to about 0.1 for $p_{\mathrm{T}}>4$ GeV. The $v_2(p_{\mathrm{T}})$, $v_3(p_{\mathrm{T}})$ and $v_4(p_{\mathrm{T}})$ are compared to the $v_n$ coefficients in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with similar event multiplicities. Reasonable agreement is observed after accounting for the difference in the average $p_{\mathrm{T}}$ of particles produced in the two collision systems.

   ↳ hep-exnucl-exPRC(2014)·264 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.