Wed·Nov 12, 2014Wednesday·November 12, 2014

1. 01*

   Activation cross-sections of deuteron induced nuclear reactions on neodymium up to 50 MeV

   F. Tárkányi🇭🇺 · S. Takács🇭🇺 · F. Ditrói🇭🇺 · A. Hermanne🇧🇪 · H. Yamazaki🇯🇵 · M. Baba · A. Mohammadi🇺🇸 · A.V. Ignatyuk

   In the frame of a systematic study of activation cross sections of deuteron induced nuclear reactions on rare earths, the reactions on neodymium for production of therapeutic radionuclides were measured for the first time. The excitation functions of the natNd(d,x) 151,150,149,148m,148g,146,144,143Pm, 149,147,139mNd, 142Pr and 139gCe nuclear reactions were assessed by using the stacked foil activation technique and high resolution $\gamma@-spectrometry. The experimental excitation functions were compared to the theoretical predictions calculated with the modified model codes ALICE-IPPE-D and EMPIRE-II-D and with the data in the TENDL-2012 library based on latest version of the TALYS code. The application of the data in the field of medical isotope production and nuclear reaction theory is discussed.

   nucl-exNucl.Instrum.Meth.B(2014)·7 citations
2. 02*

   A new study of the ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na reaction deep underground: Feasibility, setup, and first observation of the 186 keV resonance

   F. Cavanna · R. Depalo🇮🇹 · M. -L. Menzel🇩🇪 · M. Aliotta🇬🇧 · M. Anders🇩🇪 · D. Bemmerer🇩🇪 · C. Broggini🇮🇹 · C. G. Bruno · A. Caciolli🇮🇹 · P. Corvisiero🇮🇹 · T. Davinson🇬🇧 · A. di Leva🇮🇹 and 19 other authors

   The ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na cross section directly at the astrophysically relevant energies are needed. In the present work, a feasibility study for a ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na experiment at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400\,kV accelerator deep underground in the Gran Sasso laboratory, Italy, is reported. The ion beam induced $\gamma$-ray background has been studied. The feasibility study led to the first observation of the $E_{\mathrm{p}}$ = 186\,keV resonance in a direct experiment. An experimental lower limit of 0.12\,$\times$\,10${}^{-6}$\,eV has been obtained for the resonance strength. Informed by the feasibility study, a dedicated experimental setup for the ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na experiment has been developed. The new setup has been characterized by a study of the temperature and pressure profiles. The beam heating effect that reduces the effective neon gas density due to the heating by the incident proton beam has been studied using the resonance scan technique, and the size of this effect has been determined for a neon gas target.

   nucl-exastro-ph.SRphysics.ins-detEPJA(2014)·62 citations
3. 03*

   Transverse-momentum dependent parton distribution functions beyond leading twist in quark models

   C. Lorcé (Liège U. and SLAC, Stanford U.)🇺🇸 · B. Pasquini (Pavia U. and INFN, Pavia)🇮🇹 · P. Schweitzer (Connecticut U.)🇺🇸

   Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation, which makes guidance from models valuable. In this work we establish the formalism to describe unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark model. We review several other popular quark model approaches including free quark ensemble, bag, spectator and chiral quark-soliton model. We discuss how higher-twist TMDs are described in these models, and obtain results for several TMDs not discussed previously in literature. This study contributes to the understanding of non-perturbative properties of subleading twist TMDs. The results from the light-front constituent quark model are also compared to available phenomenological information, showing a satisfactory agreement.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2015)·64 citations
4. 04*

   Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions

   Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇨🇳

   The non-central Cu + Au collisions can create strong out-of-plane magnetic fields and in-plane electric fields. By using the HIJING model, we study the general properties of the electromagnetic fields in Cu + Au collisions at 200 GeV and their impacts on the charge-dependent two-particle correlator ${\gamma }_{q_1{q}_2}=<\cos ({\varphi }_1+{\varphi }_2-2{\psi }_{RP})>$ (see main text for definition) which was used for the detection of the chiral magnetic effect (CME). Compared with Au + Au collisions, we find that the in-plane electric fields in Cu + Au collisions can strongly suppress the two-particle correlator or even reverse its sign if the lifetime of the electric fields is long. Combining with the expectation that if ${\gamma }_{q_1{q}_2}$ is induced by elliptic-flow driven effects we would not see such strong suppression or reversion, our results suggest to use Cu + Au collisions to test CME and understand the mechanisms that underlie ${\gamma }_{q_1{q}_2}$.

   ↳ nucl-thhep-phnucl-exPLB(2015)·85 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.