Tue·Jan 26, 2021Tuesday·January 26, 2021

1. 01*

   Study evolution of fragment energy spectrum in compound and elemental absorber with thickness via effective charge correction

   Rajkumar Santra🇮🇳 · V.G.Vamaravalli · Ankur Roy🇮🇳 · Balaram Dey · Subinit Roy🇮🇳

   The energy loss behaviour of fission fragments (FF) from ${}^{252}$Cf(sf) in thin Mylar ($H_8{C}_{10}{O}_4$) and Aluminium absorber foils have been revisited. The aim is to investigate the observed change in the well known asymmetric energy of spontaneous fission of ${}^{252}$Cf as the fragments pass through increasingly thick absorber foils. Two different types of absorbers have been used: one elemental and the other an organic compound. The stopping powers have been determined as a function of energy for three fragment mass groups with average masses with $<A>$ = 106.5, 141.8, 125.8 corresponding to light, heavy and symmetric fragment of ${}^{252}$Cf. Using the effective charge (Z${}_{eff}$) in the stopping power relation in the classical Bohr theory best describes the stopping power data. Spectrum shape parameters, subsequently have been extracted from the energy spectra of fission fragments for different foil thickness. The effective charge (Z${}_{eff}$) correction term determined from the stopping power data is then used in the simulation for the absorber thickness dependence of the shape parameters of the energy spectrum. The present simulation results are compared with the TRIM prediction. The trends of the absorber thickness dependence of the spectrum shape parameters, for both Mylar and Aluminium are well reproduced with the present simulation.

   nucl-exIJMPE(2022)·0 citations
2. 02*

   Determination of angular distributions from the high efficiency solenoidal separator SOLITAIRE

   L. T. Bezzina · E. C. Simpson · D. J. Hinde · M. Dasgupta · I. P. Carter · D. C. Rafferty

   A novel fusion product separator, based on a gas-filled 8 T superconducting solenoid has been developed at the Australian National University. Though the transmission efficiency of the solenoid is very high, precision cross section measurements require knowledge of the angular distribution of the evaporation residues. A method has been developed to deduce the angular distribution of the evaporation residues from the laboratory-frame velocity distribution of the evaporation residues measured at the exit of the separator. The features of this method are presented, focusing on the example of ${}^{34}$S+${}^{89}$Y which is compared to an independent measurement of the angular distribution. The establishment of this method now allows the novel solenoidal separator to be used to obtain reliable, precision fusion cross-sections.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·2 citations
3. 03*

   Electromagnetic fields from the extended Kharzeev-McLerran-Warringa model in relativistic heavy-ion collisions

   Yi Chen🇨🇳 · Xin-Li Sheng🇨🇳 · Guo-Liang Ma🇨🇳

   Based on the Kharzeev-McLerran-Warringa (KMW) model that estimates strong electromagnetic (EM) fields generated in relativistic heavy-ion collisions, we generalize the formulas of EM fields in the vacuum by incorporating the longitudinal position dependence, the generalized charge distributions and retardation correction. We further generalize the formulas of EM fields in the pure quark-gluon plasma (QGP) medium by incorporating a constant Ohm electric conductivity and also during the realistic early-time stages QGP evolution by using a time-dependent electric conductivity. Using the extended KMW model, we observe a slower time evolution and a more reasonable impact parameter $b$ dependence of the magnetic field strength than those from the original KMW model in the vacuum. The inclusion of medium effects by using the lattice data helps to further prolong the time evolution of magnetic field, such that the magnetic field strength during the realistic QGP evolution at thermal freeze-out time can meet the $1\sigma$ bound constrained from experimentally measured difference in global polarizations of $\Lambda$ and $\bar{\Lambda }$ hyperons in Au+Au collisions at top RHIC energy. These generalized formulations in the extended KMW model will be potentially useful for many EM fields relevant studies in heavy-ion collisions, especially at lower colliding energies and for various species of colliding nuclei.

   ↳ nucl-thhep-phnucl-exNPA(2021)·27 citations
4. 04*

   Double-strangeness production in $\Lambda p\to K^{+}X$ reaction

   Jung Keun Ahn🇰🇷 · Seung-il Nam🇰🇷

   We investigate $S=-2$ production from the $\Lambda p\to K^{+}X$ reactions within the effective Lagrangian approach. The $\Lambda p\to K^{+}\Lambda \Lambda$ and $\Lambda p\to K^{+}{\Xi }^{-}p$ reactions are considered to find the lightest $S=-2$ system, which is $H$-dibaryon. We assume that the $H(2250)\to \Lambda \Lambda$, and $H(2270)\to {\Xi }^{-}p$ decays with the intrinsic decay width of 1 MeV. According to our calculations, the total cross-sections for $\Lambda p\to K^{+}\Lambda \Lambda$ and $\Lambda p\to K^{+}{\Xi }^{-}p$ reactions were found to be of the order of a few $\mu$b in the $\Lambda$ beam momentum range of up to 5 GeV$/c$. Furthermore, the direct access of information regarding the interference patterns between the $H$-dibaryon and non-resonant contributions was demonstrated.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·8 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.