Mon·Jul 15, 2024Monday·July 15, 2024

1. 01*

   Cross-sections of photoneutron reaction ${}^{\mathrm{nat}}$Mo($\gamma ,x$n)${}^{93m}$Mo at the bremsstrahlung energy up to 95 MeV

   I.S. Timchenko🇸🇰 · O.S. Deiev🇺🇦 · S.M. Olejnik🇺🇦 · S.M. Potin🇺🇦 · V.A. Kushnir🇺🇦 · V.V. Mytrochenko🇺🇦 · S.A. Perezhogin🇺🇦

   The photoproduction of the ${}^{93m}$Mo nucleus on natural molybdenum was studied using the electron beam of the LUE-40 linac RDC "Accelerator" NSC KIPT. Measurements were performed using the activation method and off-line $\gamma$-ray spectrometric technique. For the ${}^{\mathrm{nat}}$Mo($\gamma ,x$n)${}^{93m}$Mo reaction the experimental flux-averaged cross-section <$\sigma (E_{\gamma \max })$>_\rm m at the bremsstrahlung end-point energy range of 38--93 MeV was first time determined. The theoretical values of the yields $Y_{\mathrm{m},\mathrm{g}}(E_{\gamma \max })$ and flux-averaged cross-sections <$\sigma (E_{\gamma \max })$>${}_{\mathrm{m},\mathrm{g}}$ for the ${}^{\mathrm{nat}}$Mo($\gamma ,x$n)${}^{93m,\mathrm{g}}$Mo reactions were calculated using the cross-sections $\sigma (E_{\gamma })$ from the TALYS1.96 code for different gamma strength functions and level density models. The comparison showed strong discrepancies between the experimental values and the theoretical results of <$\sigma (E_{\gamma \max })$>${}_m$.

   nucl-exProb.Atomic Sci.Technol.(2024)·0 citations
2. 02*

   Photoproduction of the ${}^{55-57}$Co nuclei on ${}^{\mathrm{nat}}$Ni at the bremsstrahlung end-point energy of 35-94 MeV

   I.S. Timchenko O.S. Deiev · S.M. Olejnik · S.M. Potin · V.A. Kushnir · V.V. Mytrochenko · S.A. Perezhogin · A. Herzáň

   Production of the ${}^{55-57}$Co nuclei on ${}^{\mathrm{nat}}$Ni in photonuclear reactions using bremsstrahlung gamma photon irradiation with end-point energy $E_{\gamma \max }$ between 35 and 94~MeV has been studied. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT using the methods of $\gamma$ activation and off-line $\gamma$-ray spectroscopy. The obtained experimental flux-averaged cross-sections $⟨\sigma (E_{\gamma \max })⟩$ agree with the data found in literature. The theoretical flux-averaged cross-sections $⟨\sigma (E_{\gamma \max }){⟩}_{\mathrm{th}}$ for the production of ${}^{55-57}$Co and ${}^{55-57}$Ni were estimated using the cross-section values $\sigma (E)$ from the TALYS1.95 code and bremsstrahlung spectra of gamma photons calculated by GEANT4.9.2. The experimental results for ${}^{56,57}$Co agree with the cumulative $⟨\sigma (E_{\gamma \max }){⟩}_{\mathrm{th}}$. However theoretical prediction fails to reproduce the measured cross-sections for the production of ${}^{55}$Co.

   nucl-exAtom.Data Nucl.Data Tabl.(2024)·2 citations
3. 03*

   Emergence of High-Order Deformation in Rotating Transfermium Nuclei: A Microscopic Understanding

   F. F. Xu🇨🇳 · Y. K. Wang🇨🇳 · Y. P. Wang · P. Ring🇩🇪 · P. W. Zhao🇨🇳

   The rotational properties of the transfermium nuclei are investigated in the full deformation space by implementing a shell-model-like approach in the cranking covariant density functional theory on a three-dimensional lattice, where the pairing correlations, deformations, and moments of inertia are treated in a microscopic and self-consistent way. The kinematic and dynamic moments of inertia of the rotational bands observed in the transfermium nuclei ${}^{252}$No, ${}^{254}$No, ${}^{254}$Rf, and ${}^{256}$Rf are well reproduced without any adjustable parameters using a well-determined universal density functional. It is found for the first time that the emergence of the octupole deformation should be responsible for the significantly different rotational behavior observed in ${}^{252}$No and ${}^{254}$No. The present results provide a microscopic solution to the long-standing puzzle on the rotational behavior in No isotopes, and highlight the risk of investigating only the hexacontetrapole (${\beta }_{60}$) deformation effects in rotating transfermium nuclei without considering the octupole deformation.

   ↳ nucl-thnucl-exPRL(2024)·19 citations
4. 04*

   Understanding the approach to thermalization from the eigenspectrum of non-Abelian gauge theories

   Harshit Pandey🇮🇳 · Ravi Shanker🇮🇳 · Sayantan Sharma🇮🇳

   We study some interesting aspects of the spectral properties of SU(3) gauge theory, both with and without dynamical quarks (QCD) at thermal equilibrium using lattice gauge theory techniques. By calculating the eigenstates of a massless overlap Dirac operator on the gauge configurations, we implement a gauge-invariant method to study spectral properties of non-Abelian gauge theories. We have unambiguously categorized Dirac eigenvalues into different regimes based on a quantity defined in terms of the ratios of nearest neighbor spacings. While majority of these eigenstates below the magnetic scale are similar to those of random matrices belonging to the Gaussian Unitary ensemble at temperatures much higher than the chiral crossover transition in QCD, a few among them start to become prominent only near the crossover. These form fractal-like clusters with the median value for their fractal dimensions hinting at the universality class of the chiral transition in QCD. We further demonstrate that momentum modes below the magnetic scale in a particular non-equilibrium state of QCD are classically chaotic and estimate an upper bound on the thermalization time $\sim 1.44$ fm/c by matching this magnetic scale with that of a thermal state at $\sim 600$ MeV.

   ↳ hep-latcond-mat.stat-mechhep-phnucl-ex+1NPB(2026)·10 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.