Wed·May 17, 2017Wednesday·May 17, 2017

1. 01*

   The nuclear force imprints revealed on the elastic scattering of protons with ${}^{10}$C

   A. Kumar🇺🇸 · R. Kanungo🇨🇦 · A. Calci🇨🇦 · P. Navratil🇨🇦 · A. Sanetullaev🇨🇦 · M. Alcorta🇨🇦 · V. Bildstein🇨🇦 · G. Christian🇨🇦 · B. Davids🇨🇦 · J. Dohet-Eraly🇨🇦 · J. Fallis🇨🇦 · A. T. Gallant🇨🇦 and 17 other authors

   How does nature hold together protons and neutrons to form the wide variety of complex nuclei in the universe? Describing many-nucleon systems from the fundamental theory of quantum chromodynamics has been the greatest challenge in answering this question. The chiral effective field theory description of the nuclear force now makes this possible but requires certain parameters that are not uniquely determined. Defining the nuclear force needs identification of observables sensitive to the different parametrizations. From a measurement of proton elastic scattering on ${}^{10}$C at TRIUMF and ab initio nuclear reaction calculations we show that the shape and magnitude of the measured differential cross section is strongly sensitive to the nuclear force prescription.

   nucl-exnucl-thPRL(2017)·29 citations
2. 02*

   Isolating the chiral magnetic effect from backgrounds by pair invariant mass

   Jie Zhao🇺🇸 · Hanlin Li🇨🇳 · Fuqiang Wang🇺🇸

   Topological gluon configurations in quantum chromodynamics induce quark chirality imbalance in local domains, which can result in the chiral magnetic effect (CME)--an electric charge separation along a strong magnetic field. Experimental searches for the CME in relativistic heavy ion collisions via the charge-dependent azimuthal correlator ($\Delta \gamma$) suffer from large backgrounds arising from particle correlations (e.g. due to resonance decays) coupled with the elliptic anisotropy. We propose differential measurements of the $\Delta \gamma$ as a function of the pair invariant mass ($m_{\mathrm{inv}}$), by restricting to high $m_{\mathrm{inv}}$ thus relatively background free, and by studying the $m_{\mathrm{inv}}$ dependence to separate the possible CME signal from backgrounds. We demonstrate by model studies the feasibility and effectiveness of such measurements for the CME search.

   nucl-exnucl-thEPJC(2019)·56 citations
3. 03*

   Re-examining the ${}^{26}$Mg($\alpha ,{\alpha }^{\prime }$)${}^{26}$Mg reaction - probing astrophysically important states in ${}^{26}$Mg

   P. Adsley🇫🇷 · J.W. Brümmer🇿🇦 · K.C.W. Li🇿🇦 · D.J. Marín-Lámbarri🇿🇦 · N.Y. Kheswa🇿🇦 · L.M. Donaldson🇿🇦 · R. Neveling🇿🇦 · P. Papka🇿🇦 · L. Pellegri🇿🇦 · V. Pesudo🇿🇦 · L.C. Pool🇿🇦 · F.D. Smit🇿🇦 · J.J. van Zyl🇿🇦

   Background: The ${}^{22}$Ne($\alpha ,n$)${}^{25}$Mg reaction is one of the neutron sources for the $s$-process in massive stars. The properties of levels in ${}^{26}$Mg above the $\alpha$-particle threshold control the strengths of the ${}^{22}$Ne($\alpha ,n$)${}^{25}$Mg and ${}^{22}$Ne($\alpha ,\gamma$)${}^{26}$Mg reactions. The strengths of these reactions as functions of temperature are one of the major uncertainties in the $s$-process. Methods: Inelastically scattered $\alpha$ particles from a ${}^{26}$Mg target were momentum-analysed in the K600 magnetic spectrometer at iThemba LABS, South Africa. The differential cross sections of states were deduced from the focal-plane trajectory of the scattered $\alpha$ particles. Based on the differential cross sections, spin and parity assignments to states are made. Results: A new $0^{+}$ state was observed in addition to a number of other states, some of which can be associated with states observed in other experiments. Some of the deduced $J^{\pi }$ values of the states observed in the present study show discrepancies with those assigned in an experiment performed at RCNP Osaka. Conclusion: The high level density at this excitation energy in ${}^{26}$Mg makes assigning $J^{\pi }$ values to observed states difficult. Further experimental investigations with superior experimental energy resolution are required to clarify the number of levels in ${}^{26}$Mg, especially between the $\alpha$-particle threshold at 10.615 MeV and the neutron threshold at 11.319 MeV.

   nucl-exPRC(2017)·17 citations
4. 04*

   Quarkonium production in A-A and p-A collisions

   E. Scomparin🇮🇹

   Thirty years ago, the suppression of quarkonium production in heavy-ion collisions was first proposed as an unambiguous signature for the formation of a Quark-Gluon Plasma. Recent results from the LHC run 2 have led to an unprecedented level of precision on this observable and, together with new data from RHIC, are providing an accurate picture of the influence of the medium created in nuclear collisions on the various charmonium (J/$\psi$, $\psi$(2S)) and bottomonium (${\rm Y}(1S)$, ${\rm Y}(2S)$, ${\rm Y}(3S)$) states, studied via their decay into lepton pairs. In this contribution, I will review the new results presented at Quark Matter 2017, emphasizing their relation with previous experimental observations and comparing them, where possible, with theoretical calculations.

   nucl-exhep-exNPA(2017)·6 citations
5. 05*

   Measurement of the response of a liquid scintillation detector to monoenergetic electrons and neutrons

   P. C. Rout🇮🇳 · A. Gandhi · T. Basak · R. G. Thomas · C. Ghosh🇮🇳 · A. Mitra🇬🇧 · G. Mishra🇮🇳 · S. P. Behera🇮🇳 · R. Kujur · E. T. Mirgule🇮🇳 · B. K. Nayak🇺🇸 · A. Saxena🇮🇳 · Suresh Kumar🇮🇳 · V. M. Datar🇮🇳

   The response of the liquid scintillator (EJ-301 equivalent to NE-213) to the monoenergetic electrons produced in Compton scattered $\gamma$-ray tagging has been carried out for various radioactive $\gamma$-ray sources. The measured electron response is found to be linear up to $\sim$4~MeVee and the resolution of the liquid scintillator at 1~MeVee is observed to be $\sim$~11\%. The pulse shape discrimination and pulse height response of the liquid scintillator for neutrons has been measured using ${}^7$Li(p,n${}_1$)${}^7$Be*(0.429 MeV) reaction. Non linear response to mono-energetic neutrons for the liquid scintillator is observed at E${}_n$=5.3, 9.0 and 12.7 MeV. The measured response of the liquid scintillator for electrons and neutrons have been compared with Geant4 simulation.

   ↳ physics.ins-detnucl-exJINST(2018)·17 citations
6. 06*

   Description of odd-mass nuclei within the interacting boson-fermion model based on the Gogny energy density functional

   K. Nomura🇫🇷 · R. Rodríguez-Guzmán🇰🇼 · L. M. Robledo🇪🇸

   Spectroscopic properties of odd-mass nuclei are studied within the framework of the interacting boson-fermion model (IBFM) with parameters based on the Hartree-Fock-Bogoliubov (HFB) approximation. The parametrization D1M of the Gogny energy density functional (EDF) has been used at the mean-field level to obtain the deformation energy surfaces for the considered nuclei in terms of the quadrupole deformations ($\beta ,\gamma$). In addition to the energy surfaces, both single particle energies and occupation probabilities have been used as a microscopic input for building the IBFM Hamiltonian. Only three strength parameters for the particle-boson-core coupling are fitted to experimental spectra. The IBFM Hamiltonian is then used to compute the energy spectra and electromagnetic transition rates for selected odd-mass Eu and Sm nuclei as well as for ${}^{195}$Pt and ${}^{195}$Au. A reasonable agreement with the available experimental data is obtained for the considered odd-mass nuclei.

   ↳ nucl-thnucl-exPRC(2017)·24 citations
7. 07*

   Spectral shapes of forbidden argon beta decays as background component for rare-event searches

   J. Kostensalo🇫🇮 · J. Suhonen🇫🇮 · K. Zuber🇩🇪

   The spectral shape of the electrons from the two first-forbidden unique beta- decays of Ar-39 and Ar-42 were calculated for the first time to the next-to-leading order. Especially the spectral shape of the Ar-39 decay can be used to characterise this background component for dark matter searches based on argon. Alternatively, due to the low thresholds of these experiments, the spectral shape can be investigated over a wide energy range with high statistics and thus allow a sensitive comparison with the theoretical predictions. This might lead to interesting results for the ratio of the weak vector and axial-vector constants in nuclei.

   ↳ nucl-thhep-phnucl-exJ.Phys.G(2018)·11 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.