Mon·Apr 23, 2018Monday·April 23, 2018

1. 01*

   Spectroscopy of nuclei around ${}^{100}$Sn populated via two-neutron knockout reactions

   A. Corsi🇫🇷 · A. Obertelli🇫🇷 · P. Doornenbal🇯🇵 · F. Nowacki🇫🇷 · H. Sagawa🇯🇵 · Y. Tanimura🇫🇷 · N. Aoi🇯🇵 · H. Baba🇯🇵 · P. Bednarczyk🇵🇱 · S. Boissinot🇫🇷 · M. Ciemala🇵🇱 · A. Gillibert🇫🇷 and 18 other authors

   We report on the in-beam gamma spectroscopy of ${}^{102}$Sn and ${}^{100}$Cd produced via two-neutron removal from carbon and CH${}_2$ targets at about 150 MeV/nucleon beam energy. New transitions assigned to the decay of a second 2${}^{+}$ excited state at 2470(60) keV in ${}^{102}$Sn were observed. Two-neutron removal cross sections from ${}^{104}$Sn and ${}^{102}$Cd have been extracted. The enhanced cross section to the 2${}_2^{+}$ in ${}^{102}$Sn populated via the $(p,p2n)$ reaction is traced back to an increase of shell-model structure overlaps, consistent with the hypothesis that the proton-induced two-deeply-bound-nucleon removal mechanism is of direct nature.

   nucl-exPRC(2018)·7 citations
2. 02*

   Partial-Wave Analysis of $\gamma p\to K^{+}\Lambda$ using a multichannel framework

   B. C. Hunt🇺🇸 · D. M. Manley🇺🇸

   Results from a partial-wave analysis of the reaction $\gamma p\to K^{+}\Lambda$ are presented. The reaction is dominated by the $S_{11}(1650)$ and $P_{13}(1720)$ resonances at low energies and by $P_{13}(1900)$ at higher energies. There are small contributions from all amplitudes up to and including $G_{17}$, with $F_{17}$ necessary for obtaining a good fit of several of the spin observables. We find evidence for $P_{11}$(1880), $D_{13}$(2120), and $D_{15}$(2080) resonances, as well as a possible $F_{17}$ resonance near 2300 MeV, which is expected from quark-model predictions. Some predictions for $\gamma n\to K^0\Lambda$ are also included.

   nucl-exnucl-thPRC(2019)·20 citations
3. 03*

   Study and validation of a new "3D Calorimetry" of hot nuclei with the HIPSE event generator

   E. Vient🇫🇷 · L. Manduci🇫🇷 · E. Legouée🇫🇷 · L. Augey🇫🇷 · E. Bonnet🇫🇷 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · D.Dell'Aquila🇫🇷 · Q. Fable🇫🇷 · L. Francalanza🇮🇹 · J.D. Frankland🇫🇷 and 18 other authors

   In nuclear thermodynamics, the determination of the excitation energy of hot nuclei is a fundamental experimental problem. Instrumental physicists have been trying to solve this problem for several years by building the most exhaustive 4Pi detector arrays and perfecting their calorimetry techniques. In a recent paper, a proposal for a new calorimetry, called "3D calorimetry", was made. It tries to optimize the separation between the particles and fragments emitted by the Quasi-Projectile and the other possible contributions. This can be achieved by determining the experimental probability for a given nucleus of a nuclear reaction to be emitted by the Quasi-Projectile. It has been developed for the INDRA data. In the present work, we wanted to dissect and validate this new method of characterization of a hot Quasi-Projectile. So we tried to understand and control it completely to determine these limits. Using the HIPSE event generator and a software simulating the functioning of INDRA, we were able to achieve this goal and provide a quantitative estimation of the quality of the QP characterization.

   nucl-exPRC(2018)·8 citations
4. 04*

   Verification of detailed balance for $\gamma$ absorption and emission in Dy isotopes

   T. Renstrøm🇳🇴 · H. Utsunomiya🇯🇵 · H. T. Nyhus🇳🇴 · A. C. Larsen🇳🇴 · M. Guttormsen🇳🇴 · G. M. Tveten🇳🇴 · D. M. Filipescu🇷🇴 · I. Gheorghe🇷🇴 · S. Goriely🇧🇪 · S. Hilaire🇫🇷 · Y.-W. Lui🇺🇸 · J. E. Midtbø🇳🇴 and 4 other authors

   The photo-neutron cross sections of ${}^{162,163}\mathrm{Dy}$ have been measured for the first time in an energy region from the neutron threshold ($S_n$) up to $\approx$ $13$~MeV. The ($\gamma$,n) reaction was induced with quasi-monochromatic laser Compton-scattered $\gamma$ rays, produced at the NewSUBARU laboratory. The corresponding $\gamma$-ray strength functions ($\gamma$SF) have been calculated from the photo-neutron cross sections. The data are compared to reanalyzed $\gamma$SFs of ${}^{160-164}\mathrm{Dy}$, which are measured below $S_n$. The excellent agreement with the photo-neutron data at $S_n$ confirms the principle of detailed balance. Thus, a complete $\gamma$SF is established covering in total the energy region of 1 MeV $\le$ E${}_{\gamma }$ $\le$ 13 MeV. These mid-shell well-deformed dysprosium isotopes all show scissors resonances with very similar structures. We find that our data predict the same integrated scissors strength as ($\gamma ,{\gamma }^{\prime }$) data when integrated over the same energy range, which shows that the scissors mode very likely is consistent with the generalized Brink hypothesis. Finally, using the $\gamma$SFs as input in the reaction code TALYS, we have deduced radiative neutron-capture cross sections and compared them to direct measurements. We find a very good agreement within the uncertainties, which gives further support to the experimentally determined $\gamma$SFs.

   nucl-exPRC(2018)·62 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.