Tue·Dec 1, 2015Tuesday·December 1, 2015

1. 01*

   Correlations of neutron multiplicity and gamma multiplicity with fragment mass and total kinetic energy in spontaneous fission of 252Cf

   Taofeng Wang · Guangwu Li🇨🇳 · Wenhui Zhang🇨🇳 · Liping Zhu🇨🇳 · Qinghua Meng🇨🇳 · Liming Wang · Hongyin Han🇨🇳 · Haihong Xia🇨🇳 · Long Hou🇨🇳 · Ramona Vogt🇺🇸 · Jørgen Randrup🇺🇸

   The dependence of correlations of neutron multiplicity {\nu} and gamma-ray multiplicity Mg in spontaneous fission of 252Cf on fragment mass A* and total kinetic energy TKE has been investigated employing the ratio of Mg/{\nu} and the form of Mg({\nu}). We show for the first time that Mg and {\nu} have a complex correlation for heavy fragment masses, while there is a positive dependence of Mg({\nu}) for light fragment masses and for near-symmetric mass splits. The ratio Mg/{\nu} exhibits strong shell effects for the neutron magic number N = 50 and near the doubly magic number shell closure at Z = 50 and N = 82. The gamma-ray multiplicity Mg has a maximum for TKE = 165-170 MeV. Above 170 MeV Mg(TKE) is approximately linear, while it deviates significantly from a linear dependence at lower TKE. The correlation between the average neutron and gamma-ray multiplicities can be partly reproduced by model calculations.

   nucl-exPRC(2016)·22 citations
2. 02*

   Nuclear charge distribution in the spontaneous fission of 252Cf

   Taofeng Wang · Liping Zhu🇨🇳 · Liming Wang🇩🇪 · Qinghua Men · Hongyin Han🇨🇳 · Haihong Xia🇨🇳

   The measurement for charge distributions of fragments in 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a dE-E particle telescope. We found that the fragment mass dependency of the average width of the charge distribution shows a systematic decreased trend with the obvious odd-even effect. The variation of widths of charge distribution with kinetic energies shows an approximate V-shape curve due to the large number of neutron emission for the high excitation energies and cold fragmentation with low excitation energies. As for the behavior of the average nuclear charge with respect to its deviation {\Delta}Z from the unchanged charge distribution (UCD) as a function of the mass number of primary fragments A*, for asymmetric fission products {\Delta}Z is negative value, while upon approaching mass symmetry {\Delta}Z turns positive. Concerning the energy dependence of the most probable charge for given primary mass number A*, the obvious increasing tendencies for with the kinetic energies are observed. The correlation between the average nuclear charge and the primary mass number is given as linear function. The proton and neutron odd-even effects with light fragment kinetic energies are derived.

   nucl-ex0 citations
3. 03*

   Interpretation of Angular Distributions of $Z$-boson Production at Colliders

   Jen-Chieh Peng🇺🇸 · Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Oleg Teryaev🇷🇺

   High precision data of dilepton angular distributions in ${\gamma }^{\ast }/Z$ production were reported recently by the CMS Collaboration covering a broad range of the dilepton transverse momentum, $q_T$, up to $\sim 300$ GeV. Pronounced $q_T$ dependencies of the $\lambda$ and $\nu$ parameters, characterizing the ${\cos }^2\theta$ and $\cos 2\varphi$ angular distributions, were found. Violation of the Lam-Tung relation was also clearly observed. We show that the $q_T$ dependence of $\lambda$ allows a determination of the relative contributions of the $q\bar{q}$ annihilation versus the $qG$ Compton process. The violation of the Lam-Tung relation is attributed to the presence of a non-zero component of the $q-\bar{q}$ axis in the direction normal to the "hadron plane" formed by the colliding hadrons. The magnitude of the violation of the Lam-Tung relation is shown to reflect the amount of this `non-coplanarity". The observed $q_T$ dependencies of $\lambda$ and $\nu$ from the CMS and the earlier CDF data can be well described using this approach.

   ↳ hep-phhep-exnucl-exPLB(2016)·52 citations
4. 04*

   Theoretical study of fusion reactions ${}^{32}$S + ${}^{94,96}$Zr and ${}^{40}$Ca + ${}^{94,96}$Zr and quadrupole deformation of ${}^{94}$Zr

   Bing Wang🇨🇳 · Wei-Juan Zhao🇨🇳 · En-Guang Zhao🇨🇳 · Shan-Gui Zhou🇨🇳

   The dynamic coupling effects on fusion cross sections for reactions ${}^{32}$S + ${}^{94,96}$Zr and ${}^{40}$Ca + ${}^{94,96}$Zr are studied with the universal fusion function formalism and an empirical coupled channel (ECC) model. An examination of the reduced fusion functions shows that the total effect of couplings to inelastic excitations and neutron transfer channels on fusion in ${}^{32}$S + ${}^{94}$Zr (${}^{40}$Ca + ${}^{94}$Zr) is almost the same as that in ${}^{32}$S + ${}^{96}$Zr (${}^{40}$Ca + ${}^{96}$Zr). The enhancements of the fusion cross section at sub-barrier energies due to inelastic channel coupling and neutron transfer channel coupling are evaluated separately by using the ECC model. The results show that effect of couplings to inelastic excitations channels in the reactions with ${}^{94}$Zr as target should be similar as that in the reactions with ${}^{96}$Zr as target. This implies that the quadrupole deformation parameters ${\beta }_2$ of ${}^{94}$Zr and ${}^{96}$Zr should be similar to each other. However, ${\beta }_2$'s predicted from the finite-range droplet model, which are used in the ECC model, are quite different. Experiments on ${}^{48}$Ca + ${}^{94}$Zr or ${}^{36}$S + ${}^{94}$Zr are suggested to solve the puzzling issue concerning ${\beta }_2$ for ${}^{94}$Zr.

   ↳ nucl-thnucl-exSCPMA(2016)·15 citations
5. 05*

   Improved Thermometer from Intermediate Mass Fragments in Heavy-Ion Collisions with Isobaric Yield Ratio Difference

   Chun-Wang Ma🇨🇳 · Tian-Tian Ding🇨🇳 · Chun-Yuan Qiao🇨🇳 · Xi-Guang Cao🇨🇳

   \item[Background] Temperature is an important parameter in studying many important questions in heavy-ion collisions. A thermometer based on the isobaric yield ratio (IYR) has been proposed [Ma \textit{et al.}, Phys. Rev. C \textbf{86}, 054611 (2012) and Ma \textit{et al.}, \textit{ibid.}, Phys. Rev. C \textbf{88}, 014609 (2013)]. \item[Purpose] An improved thermometer ($T_{IB}$) is proposed based on the difference between IYRs. $T_{IB}$ obtained from isobars in different reactions will be compared. \item[Methods] The yields of three isobars are employed in $T_{IB}$. The residual free energy of the three isobars are replaced by that of the binding energy. No secondary decay modification for odd $A$ fragment is used in $T_{IB}$. \item[Results] The measured fragment yields in the 140$A$ MeV ${}^{40,48}$Ca + ${}^9$Be (${}^{181}$Ta) and ${}^{58,64}$Ni + ${}^9$Be (${}^{181}$Ta), the 1$A$ GeV ${}^{124,136}$Xe + Pb, and the ${}^{112,124}$Sn + ${}^{112,124}$Sn reactions have been analyzed to obtain $T_{IB}$ from IMFs. $T_{IB}$ from most of the fragments in the ${}^{40,48}$Ca and ${}^{58,64}$Ni reactions is in the range of 0.6 MeV $<T_{IB}<$ 3.5 MeV. $T_{IB}$ from most of the fragments in the ${}^{124}$Xe and ${}^{112,124}$Sn reactions is in the range of 0.5 MeV $<T_{IB}<$ 2.5 MeV, while the range is 0.5 MeV $<T_{IB}<$ 4 MeV from most of the fragments in the ${}^{136}$Xe reaction. In general, for most of the fragments $T_{IB}$ in the ${}^{40,48}$Ca and ${}^{58,64}$Ni reactions are very similar (except in the very neutron-rich fragments), and $T_{IB}$ from IMFs in the ${}^{124,136}$Xe and ${}^{112,124}$Sn reactions is also similar. A slightly dependence of $T_{IB}$ on $A$ is found. \item[Conclusions] Using the binding energy of the nucleus, $T_{IB}$ can be obtained without the knowledge of the free energies of fragments. In the investigated reactions, $T_{IB}$ from most of the IMFs is low.

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

   Sensitivity of NEXT-100 to neutrinoless double beta decay

   NEXT Collaboration: J. Martín-Albo · J. Muñoz Vidal · P. Ferrario · M. Nebot-Guinot · J.J. Gómez-Cadenas · V. Álvarez · C.D.R. Azevedo · F.I.G. Borges · S. Cárcel · S. Cebrián · A. Cervera · C.A.N. Conde and 50 other authors

   NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta ($\beta \beta 0\nu$) decay of Xe-136. The detector possesses two features of great value for $\beta \beta 0\nu$ searches: energy resolution better than 1\% FWHM at the $Q$ value of Xe-136 and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most $4\times 10^{-4}$ counts keV${}^{-1}$ kg${}^{-1}$ yr${}^{-1}$. Accordingly, the detector will reach a sensitivity to the \bbonu-decay half-life of $2.8\times 10^{25}$ years (90\% CL) for an exposure of 100 $\mathrm{kg}\cdot \mathrm{year}$, or $6.0\times 10^{25}$ years after a run of 3 effective years.

   ↳ physics.ins-dethep-exnucl-exJHEP(2016)·173 citations
7. 07*

   Gamma-gamma physics and transition form factor measurements at KLOE/KLOE-2

   Paolo Gauzzi (for the KLOE-2 COllaboration)🇮🇹

   The KLOE results on the measurement of the transition form factors of the eta and pi0 mesons in phi Dalitz decays are presented, and the determination of the Gamma(eta->gamma gamma) in gamma gamma processes is also reported. The prospects for gamma gamma physics of the new data-taking, started in November 2014 with the upgraded detector, are reviewed.

   ↳ hep-exnucl-exJ.Univ.Sci.Tech.China(2016)·1 citation
8. 08*

   Beyond-mean-field approach to low-lying spectra of $\Lambda$ hypernuclei

   K. Hagino🇯🇵 · H. Mei🇯🇵 · J.M. Yao🇯🇵 · T. Motoba🇯🇵

   Taking the hypernucleus ${}_{\Lambda }^{13}$C as an example, we illustrate the miscroscopic particle-rotor model for low-lying spectra of hypernuclei. This approach is based on the beyond-mean-field method, with the particle number and angular momentum projections. The quantum fluctuation of the mean-field is also taken into account for the core nucleus using the generator coordinate method. We show that the impurity effect of $\Lambda$ hyperon, such as a change in $B(E2)$, is well described with this model. Our calculation indicates that the most important impurity effect in $sd$-shell hypernuclei is a change in a deformation parameter rather than in a nuclear size.

   ↳ nucl-thnucl-exJPS Conf.Proc.(2017)·0 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.