Mon·Oct 24, 2022Monday·October 24, 2022

1. 01*

   High-precision mass measurement of doubly magic ${}^{208}$Pb

   Kathrin Kromer🇩🇪 · Chunhai Lyu🇩🇪 · Menno Door🇩🇪 · Pavel Filianin🇩🇪 · Zoltán Harman🇩🇪 · Jost Herkenhoff🇩🇪 · Wenjia Huang🇫🇷 · Christoph H. Keitel🇩🇪 · Daniel Lange🇩🇪 · Yuri N. Novikov🇷🇺 · Christoph Schweiger🇩🇪 · Sergey Eliseev🇩🇪 · Klaus Blaum🇩🇪

   The absolute atomic mass of ${}^{208}$Pb has been determined with a fractional uncertainty of $7\times 10^{-11}$ by measuring the cyclotron-frequency ratio $R$ of ${}^{208}$Pb${}^{41+}$ to ${}^{132}$Xe${}^{26+}$ with the high-precision Penning-trap mass spectrometer Pentatrap and computing the binding energies $E_{\text{Pb}}$ and $E_{\text{Xe}}$ of the missing 41 and 26 atomic electrons, respectively, with the ab initio fully relativistic multi-configuration Dirac-Hartree-Fock (MCDHF) method. $R$ has been measured with a relative precision of $9\times 10^{-12}$. $E_{\text{Pb}}$ and $E_{\text{Xe}}$ have been computed with an uncertainty of 9.1 eV and 2.1 eV, respectively, yielding $207.976650571(14)$ u (u$=9.3149410242(28)\times 10^8$ eV/c${}^2$) for the ${}^{208}$Pb neutral atomic mass. This result agrees within $1.2\sigma$ with that from the Atomic-Mass Evaluation (AME) 2020, while improving the precision by almost two orders of magnitude. The new mass value directly improves the mass precision of 14 nuclides in the region of Z=81-84 and is the most precise mass value with A>200. Thus, the measurement establishes a new region of reference mass values which can be used e.g. for precision mass determination of transuranium nuclides, including the superheavies.

   nucl-exphysics.atom-phEPJA(2022)·16 citations
2. 02*

   Multiplicity dependent studies for strangeness production with ALICE

   Meenakshi Sharma (ALICE Collaboration)🇮🇳

   The ALICE experiment has studied strangeness production in different collision systems (pp, p-Pb, Xe-Xe and Pb-Pb) and energies. The ratio of the strange particle yield to pion yield as a function of multiplicity for different collision energies and systems follow a continuously increasing trend ("enhancement") from low multiplicity pp to high-multiplicity Pb-Pb collisions, independent of the initial collision energy and colliding particles. It is also observed that the enhancement is larger for the particles with larger strangeness content. Several other features that were observed in large collision systems and explained as due to collective phenomena related to the formation of the Quark Gluon Plasma (QGP) are also observed in small systems. This includes the enhancement of {\Lambda}/K^{0}_{S} yield ratios at intermediate p_{T}, the evolution of the particle p_{T} spectra with multiplicity towards higher multiplicity. These unexpected results have motivated to perform further studies using the ALICE detector for understanding the mechanisms responsible for such behaviour in small systems.

   nucl-exhep-exDAE Symp.Nucl.Phys.(2023)·0 citations
3. 03*

   Renormalization of One-Pion Exchange in Higher Partial Waves in Chiral Effective Field Theory for Antinucleon-Nucleon System

   Daren Zhou🇨🇳

   The renormalization of iterated one-pion exchange (OPE) has been studied in Chiral Effective Field Theory ($\chi$EFT) for the antinucleon-nucleon ($\overline{N}N$) scattering in some partial waves (Phys. Rev. C 105, 054005 (2022)). We go further for the other higher partial waves but with total angular momenta $J\le 3$ in this paper. Contact interactions are represented by a complex spherical well in coordinate space. Changing the radius of the spherical well means changing the cutoff. We check the cutoff dependence of the phase shifts, inelasticities, and mixing angles for the partial waves, and show that contact interactions are needed at leading order in channels where the singular tensor potentials of OPE are attractive. Results are compared with the energy-dependent partial-wave analysis of $\overline{N}N$ scattering data. Comparisons between our conclusions and applications of $\chi$EFT to the nucleon-nucleon system are discussed as well.

   ↳ nucl-thhep-phnucl-exCPC(2023)·0 citations
4. 04*

   Investigating the cluster production mechanism with isospin triggering: Thermal models versus coalescence models

   Apiwit Kittiratpattana🇩🇪 · Tom Reichert🇩🇪 · Pengcheng Li🇨🇳 · Ayut Limphirat🇹🇭 · Christoph Herold🇹🇭 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪

   Isospin triggering allows to distinguish coalescence from thermal production of light clusters in heavy ion collisions. Triggering on $Y({\pi }^{-})-Y({\pi }^{+})$ allows to select very neutron or proton rich final states. The deuteron (cluster) production with coalescence ($d\propto n\cdot p$) leads then to an inverse parabolic dependence of the deuteron yield on $\Delta Y_{\pi }$. In contrast, in a thermal model, cluster production is independent on $\Delta Y_{\pi }$. The observation of a maximum deuteron (cluster) yield as function of $\Delta Y_{\pi }$ provides confirmation of the coalescence mechanism.

   ↳ nucl-thnucl-exPRC(2023)·1 citation
5. 05*

   Spatial Structure of the ${}^{12}$C Nucleus in a 3$\alpha$ Model with Deep Potentials Containing Forbidden States

   E. M. Tursunov · M. Z. Saidov · M. M. Begijonov

   The spatial structure of the lowest 0${}_1^{+}$, 0${}_2^{+}$, 2${}_1^{+}$ and 2${}_2^{+}$ states of the ${}^{12}$C nucleus is studied within the 3$\alpha$ model with the Buck, Friedrich, and Wheatley $\alpha \alpha$ potential with Pauli forbidden states in the $S$ and $D$ waves. The Pauli forbidden states in the three-body system are treated by the exact orthogonalization method. The largest contributions to the ground and excited 2${}_1^{+}$ bound states energies come from the partial waves $(\lambda ,\ell )=(2,2)$ and $(\lambda ,\ell )=(4,4)$. As was found earlier, these bound states are created by the critical eigenstates of the three-body Pauli projector in the 0${}^{+}$ and 2${}^{+}$ functional spaces, respectively. These special eigenstates of the Pauli projector are responsible for the quantum phase transitions from a weakly bound "gas-like" phase to a deep "quantum liquid" phase. In contrast to the bound states, for the Hoyle resonance 0${}_2^{+}$ and its analog state 2${}_2^{+}$, dominant contributions come from the $(\lambda ,\ell )=(0,0)$ and $(\lambda ,\ell )=(2,2)$ configurations, respectively. The estimated probability density functions for the ${}^{12}$C(0${}_1^{+}$) ground and 2${}_1^{+}$ excited bound states show mostly a triangular structure, where the $\alpha$ particles move at a distance of about 2.5 fm from each other. However, the spatial structure of the Hoyle resonance and its analog state have a strongly different structure, like ${}^8$Be + $\alpha$. In the Hoyle state, the last $\alpha$ particle moves far from the doublet at the distance between $R=3.0$ fm and $R=5.0$ fm. In the Hoyle analog 2${}_2^{+}$ state the two alpha particles move at a distance of about 15 fm, but the last $\alpha$ particle can move far from the doublet at the distance up to $R=30.0$ fm.

   ↳ nucl-thastro-ph.SRnucl-exquant-phPhys.Atom.Nucl.(2022)·0 citations
6. 06*

   Energy dependence of light hypernuclei production in heavy-ion collisions from a coalescence and statistical-thermal model perspective

   Tom Reichert🇩🇪 · Jan Steinheimer🇩🇪 · Volodymyr Vovchenko🇩🇪 · Benjamin Dönigus🇩🇪 · Marcus Bleicher🇩🇪

   A comparison of light hypernuclei production, from UrQMD+coalescence and the thermal model, in heavy ion collisions over a wide range of beam energies and system sizes is presented. We find that both approaches provide generally similar results, with differences in specific details. Especially the ratios of hypertriton to $\Lambda$ are affected by both the source radius $\Delta r$ of the coalescence procedure as well as canonical effects. On the other hand, the double ratio $S_3$ is almost independent of canonical effects, which is in contrast to coalescence. Thus, both the beam energy dependence and centrality dependence of $S_3$ can be used to constrain the hypertriton source radius. To do so the currently available data is not yet sufficient. Elliptic flow is shown to be unaffected by the source size of the nuclei and an almost perfect mass scaling of the elliptic flow is observed. Our predictions further suggest that the existence of the H-dibaryon ($\Lambda \Lambda$) seems ruled out by ALICE data.

   ↳ nucl-thnucl-exPRC(2023)·33 citations
7. 07*

   The exploration of hot and dense nuclear matter: Introduction to relativistic heavy-ion physics

   Hannah Elfner🇩🇪 · Berndt Müller🇺🇸

   This article summarizes our present knowledge about nuclear matter at the highest energy densities and its formation in relativistic heavy ion collisions. We review what is known about the structure and properties of the quark-gluon plasma and survey the observables that are used to glean information about it from experimental data.

   ↳ nucl-thnucl-exJ.Phys.G(2023)·82 citations
8. 08*

   Collective enhancement in the exciton model

   M. R. Mumpower🇺🇸 · D. Nuedecker🇺🇸 · H. Sasaki🇺🇸 · T. Kawano🇺🇸 · A. E. Lovell🇺🇸 · M. W. Herman🇺🇸 · I. Stetcu🇺🇸 · M. Dupuis🇫🇷

   The pre-equilibrium reaction mechanism is considered in the context of the exciton model. A modification to the one-particle one-hole state density is studied which can be interpreted as a collective enhancement. The magnitude of the collective enhancement is set by simulating the Lawrence Livermore National Laboratory (LLNL) pulsed-spheres neutron-leakage spectra. The impact of the collective enhancement is explored in the context of the highly deformed actinide, 239-Pu. A consequence of this enhancement is the removal of fictitious levels in the Distorted-Wave Born Approximation often used in modern nuclear reaction codes.

   ↳ nucl-thnucl-exPRC(2023)·5 citations
9. 09*

   Silicon $4\pi$ spectrometer for $\beta$-decay electrons with energies up to 3~MeV

   I.E. Alexeev🇷🇺 · S.V. Bakhlanov🇷🇺 · E.A. Chmel🇷🇺 · A.V. Derbin🇷🇺 · I.S. Drachnev🇷🇺 · I.M. Kotina🇷🇺 · M.S. Mikulich🇷🇺 · V.N. Muratova🇷🇺 · N.V. Nyazova🇷🇺 · D.A. Semenov🇷🇺 · M.V. Trushin🇷🇺 · E.V. Unzhakov🇷🇺

   We present a description of the originally developed $\beta$-spectrometer consisting of two Si(Li)-detectors with sensitive area thickness above 8~mm and $4\pi$-geometry. The full absorption spectrometer allows for direct measurements of $\beta$-spectra, disregarding the corrections to the response function induced by the electron backscattering from the crystal surface. In case of $\beta$-spectra of transitions to the excited state of the daughter isotope additional 3" BGO-detector is used in order to detect the $\gamma$-quanta in coincidence with the pair of Si(Li)-spectrometers.

   ↳ physics.ins-dethep-exhep-phnucl-ex0 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.