Fri·Jul 31, 2009Friday·July 31, 2009

1. 01*

   Some remarks about the beta-delayed alpha-decay of 16N

   L. Buchmann🇨🇦 · G. Ruprecht🇨🇦 · C. Ruiz🇨🇦

   The beta-delayed alpha-decay of 16N has been used to restrict the E1 fraction of the ground state gamma-transition in the astrophysically important 12C(alpha,gamma)16O reaction in several experiments including those performed at TRIUMF and several other laboratories. A review of the published measurements is given, and GEANT4 simulations and R-Matrix calculations are presented to further clarify the observed alpha spectra. A clear response-function, in the form of a low-energy tail from the scattering of alpha-particles in the catcher foil is observed in these simulations for any foil thickness. Contrary to claims in the literature, the simulations show that the TRIUMF measurement and those performed at Yale and Mainz originate from the same underlying spectrum. The simulations suggests that the discrepancies between the Yale and TRIUMF final results can be attributed to incorrect deconvolution methods applied in the former case. The simulations show in general that the form (width) of the spectrum is very sensitive to the catcher foil thickness. It is concluded that the TRIUMF measurement most likely represents the currently closest approximation to the true beta-delayed alpha-decay spectrum of 16N.

   nucl-ex0 citations
2. 02*

   Triggering on Hard Probes in Heavy-Ion Collisions with the CMS Experiment at the LHC

   Christof Roland (for the CMS collaboration)🇺🇸

   Studies of heavy-ion collisions at the LHC will benefit from an array of qualitatively new probes not readily available at lower collision energies. These include fully formed jets at ET > 50 GeV, Z0's and abundantly produced heavy flavors. For Pb+Pb running at LHC design luminosity, the collision rate in the CMS interaction region will exceed the available bandwidth to store data by several orders of magnitude. Therefore an efficient trigger strategy is needed to select the few percent of the incoming events containing the most interesting signatures. In this report, we will present the heavy-ion trigger strategy developed for the unique two-layer trigger system of the CMS experiment which consists of a ``Level-1'' trigger based on custom electronics and a High Level Trigger (HLT) implemented using a large cluster of commodity computers.

   nucl-exNPA(2009)·1 citation
3. 03*

   $K_s^0 Hadronization Following DIS at CLAS

   K. Hicks🇺🇸 · A. Daniel (for the CLAS Collaboration)🇺🇸

   The hadronization of $K^0$ particles was measured in semi-inclusive deep inelastic scattering (SIDIS) kinematics for several nuclear targets using the CLAS detector. Multiplicity ratios and $\Delta p_T^2$ values were extracted from the data. These results may be compared with similar values for ${\pi }^{+}$ hadronization from CLAS (at the same kinematics) and $K^{+}$ hadronization from HERMES (at higher energy transfer). The physics goal of these measurements is to understand the space-time evolution as the struck quark becomes a full-blown hadron as it propagates through nuclear matter.

   nucl-ex1 citation
4. 04*

   Continuum-continuum coupling and polarization potentials for weakly bound system

   L. F. Canto🇧🇷 · J. Lubian🇧🇷 · P. R. S. Gomes🇧🇷 · M. S. Hussein🇧🇷

   We investigate the influence of couplings among continuum states in collisions of weakly bound nuclei. For this purpose, we compare cross sections for complete fusion, breakup and elastic scattering evaluated by continuum discretized coupled channel (CDCC) calculations, including and not including these couplings. In our study, we discuss this influence in terms of the polarization potentials that reproduce the elastic wave function of the coupled coupled channel method in single channel calculations. We find that the inclusion of couplings among the continuum states renders the real part of the polarization potential more repulsive, whereas it leads to weaker apsorption to the breakup channel. We show that the non-inclusion of continuum-continuum couplings in CDCC calculations may not lead to qualitative and quantitative wrong conclusions.

   ↳ nucl-thnucl-exPRC(2009)·45 citations
5. 05*

   Isobaric incompressibility of the isospin asymmetric nuclear matter

   D.N. Basu🇮🇳 · P. Roy Chowdhury🇮🇳 · C. Samanta🇮🇳

   The isospin dependence of the saturation properties of asymmetric nuclear matter, particularly the incompressibility $K_{\infty }(X)=K_{\infty }+K_{\tau }{X}^2+O(X^4)$ at saturation density is systematically studied using density dependent M3Y interaction. The $K_{\tau }$ characterizes the isospin dependence of the incompressibility at saturation density ${\rho }_0$. The approximate expression $K_{asy}\approx K_{sym}-6L$ is often used for $K_{\tau }$ where $L$ and $K_{sym}$ represent, respectively, the slope and curvature parameters of the symmetry energy at ${\rho }_0$. It can be expressed accurately as $K_{\tau }=K_{sym}-6L-\frac{Q_0}{K_{\infty }}L$ where $Q_0$ is the third-order derivative parameter of symmetric nuclear matter at ${\rho }_0$. The results of this addendum to Phys. Rev. C 80, 011305(R) (2009) indicate that the $Q_0$ contribution to $K_{\tau }$ is not insignificant.

   ↳ nucl-thnucl-exPRC(2009)·19 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.