Thu·Feb 11, 2016Thursday·February 11, 2016

1. 01*

   Spectroscopy of ${}^{35}$P using the one-proton knockout reaction

   A. Mutschler (IPNO, GANIL)🇫🇷 · O. Sorlin (GANIL)🇫🇷 · A. Lemasson (NSCL, GANIL)🇫🇷 · D. Bazin (NSCL)🇺🇸 · C. Borcea (IFIN HH)🇷🇴 · R. Borcea (IFIN HH)🇷🇴 · A. Gade (NSCL)🇺🇸 · H. Iwasaki (NSCL)🇺🇸 · E. Khan (IPNO)🇫🇷 · A. Lepailleur (GANIL)🇫🇷 · F. Recchia (NSCL)🇺🇸 · T. Roger (GANIL)🇫🇷 and 7 other authors

   The structure of ${}^{35}$P was studied with a one-proton knockout reaction at88~MeV/u from a ${}^{36}$S projectile beam at NSCL. The $\gamma$ rays from thedepopulation of excited states in ${}^{35}$P were detected with GRETINA, whilethe ${}^{35}$P nuclei were identified event-by-event in the focal plane of theS800 spectrograph. The level scheme of ${}^{35}$P was deduced up to 7.5 MeV using$\gamma -\gamma$ coincidences. The observed levels were attributed to protonremovals from the $sd$-shell and also from the deeply-bound $p\_1/2$ orbital.The orbital angular momentum of each state was derived from the comparisonbetween experimental and calculated shapes of individual ($\gamma$-gated)parallel momentum distributions. Despite the use of different reactions andtheir associate models, spectroscopic factors, $C^{2}S$, derived from the${}^{36}$S $(-1p)$ knockout reaction agree with those obtained earlier from${}^{36}$S($d$,\nuc{3}{He}) transfer, if a reduction factor $R\_s$, as deducedfrom inclusive one-nucleon removal cross sections, is applied to the knockout transitions.In addition to the expected proton-hole configurations, other states were observedwith individual cross sections of the order of 0.5~mb. Based on their shiftedparallel momentum distributions, their decay modes to negative parity states,their high excitation energy (around 4.7~MeV) and the fact that they were notobserved in the ($d$,\nuc{3}{He}) reaction, we propose that they may resultfrom a two-step mechanism or a nucleon-exchange reaction with subsequent neutronevaporation. Regardless of the mechanism, that could not yet be clarified, thesestates likely correspond to neutron core excitations in \nuc{35}{P}. Thisnewly-identified pathway, although weak, offers the possibility to selectivelypopulate certain intruder configurations that are otherwise hard to produceand identify.

   nucl-exPRC(2016)·21 citations
2. 02*

   Activation cross-sections of proton induced reactions on ${}^{nat}$Sm up to 65 MeV

   F. Tárkányi🇭🇺 · A. Hermanne · S. Takács🇭🇺 · F. Ditrói🇭🇺 · A.V. Ignatyuk

   Activation cross sections for proton induced reactions on Sm are presented for the first time for ${}^{nat}$Sm(p,xn)${}^{154,152m2,152m1,152g,150m,150g,149,148,147,146,145}$Eu, ${}^{nat}$Sm(p,x)${}^{153,145}$Sm, ${}^{nat}$Sm(p,x)${}^{151,150,149,148g,148m,146,144,143}$Pm and ${}^{nat}$Sm(p,x)${}^{141}$Nd up to 65 MeV. The cross sections were measured via activation method by using a stacked-foil irradiation technique and high resolution gamma ray spectroscopy. The results were compared with results of the nuclear reaction codes ALICE, EMPIRE and TALYS (results taken from TENDL libraries). Integral yields of the activation products were calculated from the excitation functions.

   nucl-exNucl.Instrum.Meth.B(2015)·0 citations
3. 03*

   Multi-particle correlations in transverse momenta from statistical clusters

   Andrzej Bialas🇵🇱 · Adam Bzdak🇵🇱

   We evaluate $n$-particle ($n=2,3,4,5$) transverse momentum correlations for pions and kaons following from the decay of statistical clusters. These correlation functions could provide strong constraints on a possible existence of thermal clusters in the process of particle production.

   ↳ hep-phhep-exnucl-exPLB(2016)·0 citations
4. 04*

   Improved empirical parametrizations of the ${\gamma }^{\ast }N\to N(1535)$ transition amplitudes and the Siegert's theorem

   G. Ramalho🇧🇷

   Some empirical parametrizations of the ${\gamma }^{\ast }N\to N(1535)$ transition amplitudes violates the Siegert's theorem, that relates the longitudinal and the transverse amplitudes, in the pseudo-threshold limit (nucleon and resonance at rest). In the case of the electromagnetic transition from the nucleon (mass $M$) to the resonance $N(1525)$ (mass $M_R$), the Siegert's theorem is sometimes expressed by the relation $|\mathbf{q}|A_{1/2}=\lambda S_{1/2}$ in the pseudo-threshold limit, when the photon momentum $|\mathbf{q}|$ vanishes, and $\lambda =\sqrt{2}(M_R-M)$. In this article, we argue that the Siegert's theorem should be expressed by the relation $A_{1/2}=\lambda \frac{S_{1/2}}{|\mathbf{q}|}$, in the limit $|\mathbf{q}|\to 0$. This result is a consequence of the relation $S_{1/2}\propto |\mathbf{q}|$, when $|\mathbf{q}|\to 0$, as suggested by the analysis of the transition form factors and by the orthogonality between the nucleon and $N(1535)$ states. We propose then new empirical parametrizations for the ${\gamma }^{\ast }N\to N(1535)$ helicity amplitudes, that are consistent with the data and the Siegert's theorem. The proposed parametrization follow closely the MAID2007 parametrization, except for a small deviation in the amplitudes $A_{1/2}$ and $S_{1/2}$ when $Q^2<1.5$ GeV${}^2$.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2016)·21 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.