Wed·Aug 31, 2016Wednesday·August 31, 2016

1. 01*

   $\alpha$-induced reaction cross sections in the mass range $\mathbf{A}\approx 20-50$: a critical review

   Peter Mohr🇭🇺

   In a recent review it was shown that the cross sections of $\alpha$-induced reactions in the $A\approx 20-50$ mass range follow a general and smooth trend in most cases. For comparison of cross sections of different targets at various energies the method of reduced cross sections ${\sigma }_{\mathrm{red}}$ and reduced energies $E_{\mathrm{red}}$ was used. Four outliers were identified: ${}^{36}$Ar and ${}^{40}$Ar with unusally small cross sections and ${}^{23}$Na and ${}^{33}$S with unusually large cross sections. New data for ${}^{23}$Na were presented at this NPA-7 conference; contrary to the previous data, these new data fit into the general systematics. In addition, a relation between the most effective energy $E_0$ for astrophysical reaction rates (the so-called Gamow window) and the reduced energy $E_{\mathrm{red}}$ is presented.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2018)·2 citations
2. 02*

   New concept for pairing anti-halo effect as a localized wave packet of quasi-particle

   K. Hagino🇯🇵 · H. Sagawa🇯🇵

   The pairing anti-halo effect is a phenomenon that a pairing correlation suppresses a divergence of nuclear radius, which happens for single-particle states with orbital angular momenta of $l$ = 0 and 1 in the limit of vanishing binding energy. While this effect has mainly been discussed in terms of Hartree-Fock-Bogoliubov (HFB) theory, we here use a three-body model and provide its new intuitive concept as a localized wave packet for a quasi-particle, that is, a coherent superposition of a weakly bound and continuum wave functions due to a pairing interaction. We show that the one-particle density in the three-body model can be directly expressed with such quasi-particle wave functions, which have a close analog to wave functions in the HFB approximation.

   ↳ nucl-thnucl-exPRC(2017)·6 citations
3. 03*

   Systematic study of favored \alpha-decay half-lives of closed shell odd-A and doubly-odd nuclei related to ground and isomeric states

   Xiao-Dong Sun🇨🇳 · Ping Guo🇨🇳 · Xiao-Hua Li🇨🇳

   In this work, we systematically investigate the favored $\alpha$-decay half-lives and $\alpha$ preformation probabilities of both odd-$A$ and doubly-odd nuclei related to ground and isomeric states around the doubly magic cores at $Z=82$, $N=82$ and at $Z=82$, $N=126$, respectively, within a two-potential approach from the view of the valence nucleon (or hole). The results show that the $\alpha$ preformation probability is linear related to $N_{\text{p}}{N}_{\text{n}}$ or $N_{\text{p}}{N}_{\text{n}}I$, where $N_{\text{p}}$, $N_{\text{n}}$, and $I$ are the number of valence protons (or holes), the number of valence neutrons (or holes), and the isospin of the parent nucleus, respectively. Fitting the $\alpha$ preformation probabilities data extracted from the differences between experimental data and calculated half-lives without a shell correction, we give two analytic formulas of the $\alpha$ preformation probabilities and the values of corresponding parameters. Using those formulas and the parameters, we calculate the $\alpha$-decay half-lives for those nuclei. The calculated results can well reproduce the experimental data.

   ↳ nucl-thnucl-exPRC(2016)·42 citations
4. 04*

   Search for ${\Theta }^{+}(1540)$ emission in hadron--nucleus collisions at 400--700 GeV

   A.E. Asratyan🇷🇺 · V.A. Matveev🇷🇺

   The data on hadron--nucleus collisions at 400--700 GeV, collected by the SELEX experiment at Fermilab, are analyzed for formation of the exotic pentaquark baryon ${\Theta }^{+}(1540)$. A narrow enhancement near 1539 MeV is observed in the mass spectrum of the $p{K}_S^0$ system emitted at small $x_F$ from hadron collisions with copper nuclei. The statistical significance of the peak is near 9 standard deviations. Fitted width of the observed $p{K}_S^0$ resonance is consistent with being entirely due to experimental resolution, and its intrinsic width is restricted to $\Gamma <3$ MeV at 90\% CL. The data favor positive rather than negative strangeness for the $p{K}_S^0$ resonance observed in $h$Cu collisions. At the same time, the $p{K}_S^0$ mass spectrum for collisions in carbon is featureless. The yield of ${\Theta }^{+}$ baryons per $h$C collision is restricted to be $<24$\% of the yield per $h$Cu collision.

   ↳ hep-exnucl-ex1 citation

* 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.