Tue·Jan 6, 2015Tuesday·January 6, 2015

1. 01*

   Forward-backward emission of target evaporated evaporated fragments at high energy nucleus-nucleus collisions

   Zhi Zhang🇨🇳 · Tian-Li Ma🇨🇳 · Dong-Hai Zhang🇨🇳

   The multiplicity distribution, multiplicity moment, scaled variance, entropy and reduced entropy of target evaporated fragment emitted in forward and backward hemispheres in 12 A GeV ${}^4$He, 3.7 A GeV ${}^{16}$O, 60 A GeV ${}^{16}$O, 1.7 A GeV ${}^{84}$Kr and 10.7 A GeV ${}^{197}$Au induced emulsion heavy targets (AgBr) interactions are investigated. It is found that the multiplicity distribution of target evaporated fragments emitted in forward and backward hemispheres can be fitted by a Gaussian distribution. The multiplicity moments of target evaporated particles emitted in forward and backward hemispheres increase with the order of the moment {\em q}, and second-order multiplicity moment is energy independent over the entire energy for all the interactions in the forward and backward hemisphere respectively. The scaled variance, a direct measure of multiplicity fluctuations, is close to one for all the interactions which may be said that there is a feeble correlation among the produced particles. The entropy of target evaporated fragments emitted in forward and backward hemispheres are the same within experimental errors, respectively.

   nucl-exCPC(2015)·2 citations
2. 02*

   Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems

   P. Marini · H. Zheng · M. Boisjoli · G. Verde · A. Chbihi · G. Ademard · L. Auger · C. Bhattacharya · B. Borderie · R. Bougault · J. Frankland · E. Galichet and 15 other authors

   We report experimental signals of Bose-Einstein condensation in the decay of hot Ca projectile-like sources produced in mid-peripheral collisions at sub-Fermi energies. The experimental setup, constituted by the coupling of the INDRA 4$\pi$ detector array to the forward angle VAMOS magnetic spectrometer, allowed us to reconstruct the mass, charge and excitation energy of the decaying hot projectile-like sources. Furthermore, by means of quantum fluctuation analysis techniques, temperatures and mean volumes per particle "as seen by" bosons and fermions separately are correlated to the excitation energy of the reconstructed system. The obtained results are consistent with the production of dilute mixed (bosons/fermions) systems, where bosons experience a smaller volume as compared to the surrounding fermionic gas. Our findings recall similar phenomena observed in the study of boson condensates in atomic traps.

   nucl-exPLB(2016)·24 citations
3. 03*

   Dipolar degrees of freedom and Isospin equilibration processes in Heavy Ion collisions

   M.Papa · I. Berceanu · L. Acosta · F. Amorini · C. Agodi · A. Anzalone · L. Auditore · G. Cardella · S. Cavallaro · M.B. Chatterjee · E. De Filippo · L. Francalanza and 20 other authors

   Background: In heavy ion collision at the Fermi energies Isospin equilibration processes occur- ring when nuclei with different charge/mass asymmetries interacts have been investigated to get information on the nucleon-nucleon Iso-vectorial effective interaction. Purpose: In this paper, for the system 48Ca +27 Al at 40 MeV/nucleon, we investigate on this process by means of an observable tightly linked to isospin equilibration processes and sensitive in exclusive way to the dynamical stage of the collision. From the comparison with dynamical model calculations we want also to obtain information on the Iso-vectorial effective microscopic interaction. Method: The average time derivative of the total dipole associated to the relative motion of all emitted charged particles and fragments has been determined from the measured charges and velocities by using the 4? multi-detector CHIMERA. The average has been determined for semi- peripheral collisions and for different charges Zb of the biggest produced fragment. Experimental evidences collected for the systems 27Al+48Ca and 27Al+40Ca at 40 MeV/nucleon used to support this novel method of investigation are also discussed.

   nucl-exPRC(2015)·13 citations
4. 04*

   Neutron Knockout on Beams of ${}^{108,106}$Sn and ${}^{106}$Cd

   Giordano Cerizza

   Characterizing the nature of single-particle states outside of double shell closures is essential to a fundamental understanding of nuclear structure. This is especially true for those doubly magic nuclei that lie far from stability and where the shell closures influence nucleo-synthetic pathways. The region around ${}^{100}$Sn is one of the most important due to the proximity of the N=Z=50 magic numbers, the proton-drip line, and the end of the rp-process. However, owing to the low production rates, there is a lack of spectroscopic information and no firm spin-parity assignment for ground states of odd-A isotopes close to ${}^{100}$Sn. Neutron knockout reaction experiments on beams of ${}^{108,106}$Sn and ${}^{106}$Cd have been performed at the NSCL. By measuring gamma rays and momentum distributions from reaction residues, the spin of ground state and first excited state for ${}^{107,105}$Sn have been established. The results also show a degree of mixing in the ground states of the isotopes ${}^{108,106}$Sn between the d${}_{5/2}$ and g${}_{7/2}$ single particle-states and they are compared to reaction calculations. Single-, double-, and triple-neutron knockout reactions on the ${}^{106}$Cd beam have been observed. The spin-parity of ${}^{105}$Cd is already known, therefore, the measurement of the momentum distributions of the ground and first excited states of this residue is an important validation of the technique used for the light tin isotopes.

   nucl-ex0 citations
5. 05*

   The internal structures of the nucleon resonances $N(1875)$ and $N(2120)$

   Jun He🇨🇳

   A nucleon resonance with spin-parity $J^P=3/2^{-}$ and mass about 2.1 GeV is essential to reproduce the photoproduction cross sections for $\Lambda (1520)$ released by the LEPS and CLAS Collaborations. It can be explained as the third nucleon resonance state $[3/2^{-}{]}_3$ in the constituent quark model so that there is no position to settle the $N(1875)$ which is listed in the PDG as the third $N3/2^{-}$ nucleon resonance. An interpretation is proposed that the $N(1875)$ is from the interaction of a decuplet baryon $\Sigma (1385)$ and a octet meson $K$, which is favored by a calculation of binding energy and decay pattern in a Bethe-Salpeter approach.

   ↳ nucl-thhep-lathep-phnucl-exPRC(2015)·45 citations
6. 06*

   The scissors mode from a different perspective

   Matthew Harper · Larry Zamick🇺🇸

   The scissors mode, a magnetic dipole excitation-mainly orbital is usually discussed in terms of a transition from a J=0^{+} ground state to a J=1^{+} excited state. This is understandable because it follows from the way the experiment is performed-e.g. inelastic electron scattering. Here however, we start with the excited 1^{+} state and consider all possible transitions to J=0,1 and 2 states.

   ↳ nucl-thnucl-exphysics.atom-phPRC(2015)·8 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.