Mon·May 11, 2015Monday·May 11, 2015

1. 01*

   Oscillations above the barrier in the fusion of 28Si + 28Si

   G. Montagnoli · A. M. Stefanini🇮🇹 · H. Esbensen🇺🇸 · L. Corradi · S. Courtin🇫🇷 · E. Fioretto · J. Grebosz · F. Haas🇩🇪 · H. M. Jia · C. L. Jiang · M. Mazzocco🇩🇪 · C. Michelagnoli🇫🇷 and 7 other authors

   Fusion cross sections of 28Si + 28Si have been measured in a range above the barrier with a very small energy step (DeltaElab = 0.5 MeV). Regular oscillations have been observed, best evidenced in the first derivative of the energy-weighted excitation function. For the first time, quite different behaviors (the appearance of oscillations and the trend of sub-barrier cross sections) have been reproduced within the same theoretical frame, i.e., the coupled-channel model using the shallow M3Y+repulsion potential. The calculations suggest that channel couplings play an important role in the appearance of the oscillations, and that the simple relation between a peak in the derivative of the energy-weighted cross section and the height of a centrifugal barrier is lost, and so is the interpretation of the second derivative of the excitation function as a barrier distribution for this system, at energies above the Coulomb barrier.

   nucl-exnucl-thPLB(2015)·16 citations
2. 02*

   Crystal growth and detector performance of large size high-purity Ge crystals

   Guojian Wang🇺🇸 · Mark Amman🇺🇸 · Hao Mei🇺🇸 · Dongming Mei🇺🇸 · Klaus Irmscher🇩🇪 · Yutong Guan🇺🇸 · Gang Yang🇺🇸

   High-purity germanium crystals approximately 12 cm in diameter were grown in a hydrogen atmosphere using the Czochralski method. The dislocation density of the crystals was determined to be in the range of 2000 - 4200 cm-2, which meets a requirement for use as a radiation detector. The axial and radial distributions of impurities in the crystals were measured and are discussed. A planar detector was also fabricated from one of the crystals and then evaluated for electrical and spectral performance. Measurements of gamma-ray spectra from Cs-137 and Am-241 sources demonstrate that the detector has excellent energy resolution.

   ↳ physics.ins-detnucl-ex5 citations
3. 03*

   Modeling of heavy-flavor pair correlations in Au-Au collisions at 200 A GeV at the BNL Relativistic Heavy Ion Collider

   Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳 · Steffen A. Bass🇺🇸

   We study the nuclear modification of angular and momentum correlations between heavy quark pairs in ultrarelativistic heavy-ion collisions. The evolution of heavy quarks inside the thermalized medium is described via a modified Langevin approach that incorporates both elastic and inelastic interactions with the medium constituents. The spacetime evolution of the fireball is obtained from a (2+1)-dimensional viscous hydrodynamics simulation. The hadronization of heavy quarks is performed utilizing a hybrid model of fragmentation and coalescence. Our results show that the nuclear modification of the transverse momentum imbalance of D\bar{D} pairs reflects the total energy loss experienced by the heavy quarks and may help us probe specific regions of the medium. The angular correlation of heavy flavor pairs, especially in the low to intermediate transverse momentum regime, is sensitive to the detailed energy loss mechanism of heavy quarks inside the QGP.

   ↳ nucl-thhep-phnucl-exPRC(2015)·56 citations
4. 04*

   Non-resonant kaon pair production and medium effects in proton-nucleus collisions

   E. Ya. Paryev🇷🇺 · M. Hartmann🇩🇪 · Yu. T. Kiselev🇷🇺

   We study the non-resonant (non-$\varphi$) production of $K^{+}{K}^{-}$ pairs by protons of 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets within the collision model, based on the nuclear spectral function, for incoherent primary proton--nucleon and secondary pion--nucleon creation processes. The model takes into account the initial proton and final kaon absorption, target nucleon binding and Fermi motion as well as nuclear mean-field potential effects on these processes. We calculate the antikaon momentum dependences of the exclusive absolute and relative $K^{+}{K}^{-}$ pair yields in the acceptance window of the ANKE magnetic spectrometer, used in a recent experiment performed at COSY, within the different scenarios for the antikaon-nucleus optical potential. We demonstrate that the above observables are strongly sensitive to this potential. Therefore, they can be useful to help determine the $K^{-}$ optical potential from the direct comparison of the results of our calculations with the data from the respective ANKE-at-COSY experiment. We also show that the pion--nucleon production channels dominate in the low-momentum $K^{-}$, $K^{+}$ production in the considered kinematics and, hence, they have to be accounted for in the analysis of these data.

   ↳ nucl-thnucl-exJ.Phys.G(2015)·9 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.