Tue·Mar 31, 2015Tuesday·March 31, 2015

1. 01*

   Dipole polarizability of 120Sn and nuclear energy density functionals

   T. Hashimoto · A. M. Krumbholz · P.-G. Reinhard · A. Tamii · P. von Neumann-Cosel · T. Adachi · N. Aoi · C. A. Bertulani · H. Fujita · Y. Fujita · E. Ganioǧlu · K. Hatanaka and 23 other authors

   The electric dipole strength distribution in 120Sn between 5 and 22 MeV has been determined at RCNP Osaka from a polarization transfer analysis of proton inelastic scattering at E_0 = 295 MeV and forward angles including 0{\deg}. Combined with photoabsorption data an electric dipole polarizability \alpha_D(120Sn) = 8.93(36) fm^3 is extracted. The dipole polarizability as isovector observable par excellence carries direct information on the nuclear symmetry energy and its density dependence. The correlation of the new value with the well established \alpha_D(208Pb) serves as a test of its prediction by nuclear energy density functionals (EDFs). Models based on modern Skyrme interactions describe the data fairly well while most calculations based on relativistic Hamiltonians cannot.

   nucl-exnucl-thPRC(2015)·106 citations
2. 02*

   Precise determination of ${}_{\Lambda }^{12}$C level structure by $\gamma$-ray spectroscopy

   K. Hosomi🇯🇵 · T. Ma🇯🇵 · S. Ajimura🇯🇵 · K. Aoki🇯🇵 · S. Dairaku🇯🇵 · Y. Y. Fu🇨🇳 · H. Fujioka🇯🇵 · K. Futatsukawa🇯🇵 · W. Imoto🇯🇵 · Y. Kakiguchi🇯🇵 · M. Kawai🇯🇵 · S. Kinoshita🇯🇵 and 21 other authors

   Level structure of the ${}_{\Lambda }^{12}$C hypernucleus was precisely determined by means of $\gamma$-ray spectroscopy. We identified four $\gamma$-ray transitions via the ${}^{12}$C$({\pi }^{+},K^{+}\gamma )$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $(2_1^{-},1_1^{-})$ was measured to be $161.5\pm 0.3\text{(stat)}\pm 0.3\text{(syst)}$\,keV from the direct $M1$ transition. Excitation energies of the $1_2^{-}$ and $1_3^{-}$ states were measured to be $2832\pm 3\pm 4$\,keV and $6050\pm 8\pm 7$\,keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $\Lambda$ hypernuclei.

   nucl-exnucl-thPTEP(2015)·14 citations
3. 03*

   Spectroscopy of ${}^{28}$Na: shell evolution toward the drip line

   A. Lepailleur (GANIL) · K. Wimmer · A. Mutschler (IPNO) · O. Sorlin (GANIL) · V. Bader · C. Bancroft · D. Barofsky · B. Bastin (GANIL) · T. Baugher · D. Bazin · V. Bildstein · C. Borcea and 31 other authors

   Excited states in ${}^{28}$Na have been studied using the $\beta$-decay of implanted ${}^{28}$Ne ions at GANIL/LISE as well as the in-beam $\gamma$-ray spectroscopy at the NSCL/S800 facility. New states of positive (J${}^{\pi }$=3,4${}^{+}$) and negative (J${}^{\pi }$=1-5${}^{-}$) parity are proposed. The former arise from the coupling between 0d$\_5/2$ protons and a 0d$\_3/2$ neutron, while the latter are due to couplings with 1p$\_3/2$ or 0f$\_7/2$ neutrons. While the relative energies between the J${}^{\pi }$=1-4${}^{+}$ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between ${}^{26}$F and ${}^{30}$Al. This points to a possible change in the proton-neutron 0d$\_5/2$-0d$\_3/2$ effective interaction when moving from stability to the drip line. The presence of J${}^{\pi }$=1-4${}^{-}$ negative parity states around 1.5 MeV as well as of a candidate for a J${}^{\pi }$=5${}^{-}$ state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f$\_7/2$ and 1p$\_3/2$ levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the ${}^{26}$F and ${}^{25}$O nuclei.

   nucl-exPRC(2015)·9 citations
4. 04*

   New measurement of the d(d,p)t reaction at astrophysical energies via the Trojan-horse method

   Chengbo Li · Qungang Wen · Yuanyong Fu🇨🇳 · Jing Zhou · Shuhua Zhou🇨🇳 · Qiuying Meng🇨🇳 · C. Spitaleri🇮🇹 · A. Tumino🇮🇹 · R. G. Pizzone🇮🇹 · L. Lamia🇮🇹

   The study of d(d,p)t reaction is very important for the nucleosynthesis in both standard Big Bang and stellar evolution, as well as for the future fusion reactors planning of energy production. The d(d,p)t bare nucleus astrophysical S(E) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan horse method applied to the quasi-free process ${}^2\mathrm{H}({}^6\mathrm{Li},\mathrm{pt}){}^4\mathrm{He}$ induced at a lithium beam energy of 9.5 MeV, which is closer to the zero quasi-free energy point. An accurate analysis leads to the determination of the ${\mathrm{S}}_{\mathrm{bare}}(0)=56.7\pm 2.0keV\cdot \mathrm{b}$ and of the corresponding electron screening potential ${\mathrm{U}}_{\mathrm{e}}=13.2\pm 4.3eV$. In addition, this work gives an updated test for the Trojan horse nucleus invariance comparing with previous indirect investigations using ${}^3\mathrm{He}=(\mathrm{d}+\mathrm{p})$ breakup.

   nucl-exPRC(2015)·33 citations
5. 05*

   New $\alpha$ ANC measurement of the 1/2${}^{+}$ state in ${}^{17}$O at 6.356 MeV, that dominates the ${}^{13}$C($\alpha$,n)${}^{16}$O reaction rate at temperatures relevant for the s-process

   M. L. Avila · G. V. Rogachev🇺🇸 · E. Koshchiy · L. T. Baby🇺🇸 · J. Belarge · K. W. Kemper🇺🇸 · A. N. Kuchera🇺🇸 · D. Santiago-Gonzalez

   Background: Accurate knowledge of the ${}^{13}$C($\alpha$,$n$)${}^{16}$O reaction cross section is important for the understanding of the s-process in AGB stars, since it is considered to be the main source of neutrons. The sub-threshold 1/2${}^{+}$ state at excitation energy of 6.356 MeV in ${}^{17}$O has a strong influence on the reaction cross section at energies relevant for astrophysics. Several experiments have been performed to determine the contribution of this state to the ${}^{13}$C($\alpha ,n{)}^{16}$O reaction rate. Nevertheless, significant discrepancies between different measurements remain. Purpose: The aim of this work is to investigate these discrepancies. Method: An 8 MeV ${}^{13}$C beam (below the Coulomb barrier) was used to study the $\alpha$-transfer reaction ${}^6$Li(${}^{13}$C,$d$)${}^{17}$O. Results: The squared Coulomb modified ANC of the 1/2${}^{+}$ state in ${}^{17}$O measured in this work is $({\tilde{C}}_{\alpha {-}^{13}\text{C}}^{{}^{17}\text{O}(1/2+)}{)}^2=3.6\pm 0.7{\text{fm}}^{-1}$. Conclusions: Discrepancy between the results of $\alpha$-transfer experiments have been resolved. However, some discrepancy with the most recent measurement using the Trojan Horse method remains.

   nucl-exPRC(2015)·35 citations
6. 06*

   Constraining nucleon high momentum in nuclei

   Gao-Chan Yong🇨🇳

   Recent studies at Jefferson Lab show that there are a certain proportion of nucleons in nuclei have momenta greater than the so-called nuclear Fermi momentum $p_F$. Based on the transport model of nucleus-nucleus collisions at intermediate energies, nucleon high momentum caused by the neutron-proton short-range correlations in nuclei is constrained by comparing with $\pi$ and photon experimental data and considering some uncertainties. The high momentum cutoff value $p_{max}$ $\le$ 2$p_F$ is obtained.

   ↳ nucl-thnucl-exPLB(2017)·44 citations
7. 07*

   Measurement of a false electric dipole moment signal from ${}^{199}$Hg atoms exposed to an inhomogeneous magnetic field

   S. Afach🇨🇭 · C. A. Baker🇬🇧 · G. Ban🇫🇷 · G. Bison🇨🇭 · K. Bodek🇵🇱 · Z. Chowdhuri🇨🇭 · M. Daum🇨🇭 · M. Fertl🇨🇭 · B. Franke🇨🇭 · P. Geltenbort🇫🇷 · K. Green🇬🇧 · M. G. D. van der Grinten🇬🇧 and 37 other authors

   We report on the measurement of a Larmor frequency shift proportional to the electric-field strength for ${}^{199}\mathrm{Hg}$ atoms contained in a volume permeated with aligned magnetic and electric fields. This shift arises from the interplay between the inevitable magnetic field gradients and the motional magnetic field. The proportionality to electric-field strength makes it apparently similar to an electric dipole moment (EDM) signal, although unlike an EDM this effect is P- and T-conserving. We have used a neutron magnetic resonance EDM spectrometer, featuring a mercury co-magnetometer and an array of external cesium magnetometers, to measure the shift as a function of the applied magnetic field gradient. Our results are in good agreement with theoretical expectations.

   ↳ physics.atom-phnucl-exEur.Phys.J.D(2015)·26 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.