Fri·Aug 29, 2014Friday·August 29, 2014

1. 01*

   Novel technique for constraining r-process (n,$\gamma$) reaction rates

   A. Spyrou🇺🇸 · S. N. Liddick🇺🇸 · A. C. Larsen🇳🇴 · M. Guttormsen🇳🇴 · K. Cooper · A. C. Dombos🇺🇸 · D. J. Morrissey🇺🇸 · F. Naqvi🇺🇸 · G. Perdikakis🇺🇸 · S. J. Quinn🇺🇸 · T. Renstrøm🇳🇴 · J. A. Rodriguez and 3 other authors

   A novel technique has been developed, which will open exciting new opportunities for studying the very neutron-rich nuclei involved in the r-process. As a proof-of-principle, the $\gamma$-spectra from the $\beta$-decay of ${}^{76}$Ga have been measured with the SuN detector at the National Superconducting Cyclotron Laboratory. The nuclear level density and $\gamma$-ray strength function are extracted and used as input to Hauser-Feshbach calculations. The present technique is shown to strongly constrain the ${}^{75}$Ge($n,\gamma$)${}^{76}$Ge cross section and reaction rate.

   nucl-exPRL(2014)·148 citations
2. 02*

   Measurement of the ${}^{12}$C($n,p$)${}^{12}$B cross section at n_TOF (CERN) by in-beam activation analysis

   P. Žugec · N. Colonna · D. Bosnar · A. Mengoni · S. Altstadt · J. Andrzejewski · L. Audouin · M. Barbagallo · V. Bécares · F. Bečvář · F. Belloni · E. Berthoumieux and 92 other authors

   The integral cross section of the ${}^{12}$C($n,p$)${}^{12}$B reaction has been determined for the first time in the neutron energy range from threshold to several GeV at the n_TOF facility at CERN. The measurement relies on the activation technique, with the $\beta$-decay of ${}^{12}$B measured over a period of four half-lives within the same neutron bunch in which the reaction occurs. The results indicate that model predictions, used in a variety of applications, are mostly inadequate. The value of the integral cross section reported here can be used as a benchmark for verifying or tuning model calculations.

   nucl-exPRC(2014)·18 citations
3. 03*

   Ab Initio Multi-Reference In-Medium Similarity Renormalization Group Calculations of Even Calcium and Nickel Isotopes

   H. Hergert🇺🇸 · S. K. Bogner🇺🇸 · T. D. Morris🇺🇸 · S. Binder🇩🇪 · A. Calci🇩🇪 · J. Langhammer🇩🇪 · R. Roth🇩🇪

   We use the newly developed Multi-Reference In-Medium Similarity Renormalization Group to study all even isotopes of the calcium and nickel isotopic chains, based on two- plus three-nucleon interactions derived from chiral effective field theory. We present results for ground-state and two-neutron separation energies and quantify their theoretical uncertainties. At shell closures, we find excellent agreement with Coupled Cluster results obtained with the same Hamiltonians. Our results highlight the importance of the chiral 3N interaction to obtain a correct reproduction of experimental energy trends, and their subtle impact on the location of the neutron drip lines in the Ca and Ni chains. At the same time, we uncover and discuss deficiencies of the input Hamiltonians which need to be addressed by the next generation of chiral interactions.

   ↳ nucl-thnucl-exPRC(2014)·136 citations
4. 04*

   Lambda-Lambda interaction from relativistic heavy-ion collisions

   Kenji Morita🇯🇵 · Takenori Furumoto🇯🇵 · Akira Ohnishi🇯🇵

   We investigate the two-particle intensity correlation function of $\Lambda$ in relativistic heavy-ion collisions. We find that the behavior of the $\Lambda \Lambda$ correlation function at small relative momenta is fairly sensitive to the interaction potential and collective flows. By comparing the results of different source functions and potentials, we explore the effect of intrinsic collective motions on the correlation function. We find that the recent STAR data gives a strong constraint on the scattering length and effective range of $\Lambda \Lambda$ interaction as, $-1.8{\mathrm{fm}}^{-1}<1/a_0<-0.8{\mathrm{fm}}^{-1}$ and $3.5\mathrm{fm}<r_{\mathrm{eff}}<7\mathrm{fm}$, respectively,if $\Lambda$ samples do not include feed-down contribution from long-lived particles. We find that feed-down correction for ${\Sigma }^0$ decay reduces the sensitivity of the correlation function to the detail of the $\Lambda \Lambda$ interaction. As a result, we obtain a weaker constraint $1/a_0<-0.8$ fm${}^{-1}$. Implication for the signal of existence of $H$-dibaryon is discussed. Comparison with the scattering parameters obtained from the double $\Lambda$ hypernucleus may reveal in-medium effects in the $\Lambda \Lambda$ interaction.

   ↳ nucl-thhep-phnucl-exPRC(2015)·124 citations
5. 05*

   Dynamic stabilization of the magnetic field surrounding the neutron electric dipole moment spectrometer at the Paul Scherrer Institute

   S. Afach🇨🇭 · G. Bison🇨🇭 · K. Bodek🇵🇱 · F. Burri🇨🇭 · Z. Chowdhuri🇨🇭 · M. Daum🇨🇭 · M. Fertl🇨🇭 · B. Franke🇨🇭 · Z. Grujic🇨🇭 · V. Helaine🇨🇭 · R. Henneck🇨🇭 · M. Kasprzak🇨🇭 and 25 other authors

   The Surrounding Field Compensation (SFC) system described in this work is installed around the four-layer Mu-metal magnetic shield of the neutron electric dipole moment spectrometer located at the Paul Scherrer Institute. The SFC system reduces the DC component of the external magnetic field by a factor of about 20. Within a control volume of approximately 2.5m x 2.5m x 3m disturbances of the magnetic field are attenuated by factors of 5 to 50 at a bandwidth from $10^{-3}$ Hz up to 0.5 Hz, which corresponds to integration times longer than several hundreds of seconds and represent the important timescale for the nEDM measurement. These shielding factors apply to random environmental noise from arbitrary sources. This is achieved via a proportional-integral feedback stabilization system that includes a regularized pseudoinverse matrix of proportionality factors which correlates magnetic field changes at all sensor positions to current changes in the SFC coils.

   ↳ physics.ins-detnucl-exphysics.atom-phJ.Appl.Phys.(2014)·37 citations
6. 06*

   Channeling Effect in Polycrystalline Deuterium-Saturated CVD Diamond Target Bombarded by Deuterium Ion Beam

   A. V. Bagulya · O. D. Dalkarov · M. A. Negodaev🇩🇪 · A. S. Rusetskii · A. P. Chubenko · V. G. Ralchenko · A. P. Bolshakov

   At the ion accelerator HELIS at the LPI, the neutron yield is investigated in DD reactions within a polycrystalline deuterium-saturated CVD diamond, during an irradiation of its surface by a deuterium ion beam with the energy less than 30 keV. The measurements of the neutron flux in the beam direction are performed in dependence on the target angle, \b{eta}, with respect to the beam axis. These measurements are performed using a multichannel detector based on He3 counters. A significant anisotropy in neutron yield is observed, it was higher by a factor of 3 at \b{eta}=0 compared to that at \b{eta} = +-45{\deg}. The possible reasons for the anisotropy, including ion channeling, are discussed.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2015)·6 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.