Wed·Dec 14, 2022Wednesday·December 14, 2022

1. 01*

   Search for ${}^{22}$Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes

   C. Fougères · F. de Oliveira Santos · J. José · C. Michelagnoli · E. Clément · Y.H. Kim · A. Lemasson · V. Guimaraes · D. Barrientos · D. Bemmerer · G. Benzoni · A.J. Boston and 49 other authors

   Classical novae are thermonuclear explosions in stellar binary systems, and important sources of ${}^{26}$Al and ${}^{22}$Na. While gamma rays from the decay of the former radioisotope have been observed throughout the Galaxy, ${}^{22}$Na remains untraceable. The half-life of ${}^{22}$Na (2.6 yr) would allow the observation of its 1.275 MeV gamma-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of the nuclear reactions involved in the production and destruction of this nucleus. The ${}^{22}$Na($p,\gamma$)${}^{23}$Mg reaction remains the only source of large uncertainty about the amount of ${}^{22}$Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in ${}^{23}$Mg. In the present work, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this novel method to the study of the ${}^{23}$Mg states, combining magnetic and highly-segmented tracking gamma-ray spectrometers, places strong limits on the amount of ${}^{22}$Na produced in novae, explains its non-observation to date in gamma rays (flux < 2.5x$10^{-4}$ ph/(cm${}^2$s)), and constrains its detectability with future space-borne observatories.

   nucl-exastro-ph.HEastro-ph.SRNature Commun.(2023)·10 citations
2. 02*

   News on strangeness production from NA61/SHINE

   Maciej P. Lewicki🇵🇱

   NA61/SHINE is a fixed target experiment at the CERN Super Proton Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this talk, the new results on identified charged kaon production in the intermediate size system (Ar+Sc and Be+Be) collisions at SPS beam momentum range (13A-150A GeV/c) will be shown. Additionally, the new measurements of strange mesons (KS0), resonances (K0*(892), Xi(1530) 0 and Xi0(1530)) and baryons (Xi-(1321), Xi+(1321)) produced in p+p interactions are presented.

   nucl-exhep-exActa Phys.Polon.Supp.(2023)·2 citations
3. 03*

   First measurement of prompt and non-prompt ${\mathrm{D}}^{\ast +}$ vector meson spin alignment in pp collisions at $\sqrt{s}=13$ TeV

   ALICE Collaboration

   This letter reports the first measurement of spin alignment, with respect to the helicity axis, for ${\mathrm{D}}^{\ast +}$ vector mesons and their charge conjugates from charm-quark hadronisation (prompt) and from beauty-meson decays (non-prompt) in hadron collisions. The measurements were performed at midrapidity ($|y|<0.8$) as a function of transverse momentum ($p_{\mathrm{T}}$) in proton-proton (pp) collisions collected by ALICE at the centre-of-mass energy $\sqrt{s}=13$ TeV. The diagonal spin density matrix element ${\rho }_{00}$ of ${\mathrm{D}}^{\ast +}$ mesons was measured from the angular distribution of the ${\mathrm{D}}^{\ast +}\to {\mathrm{D}}^0(\to {\mathrm{K}}^{-}{\pi }^{+}){\pi }^{+}$ decay products, in the ${\mathrm{D}}^{\ast +}$ rest frame, with respect to the ${\mathrm{D}}^{\ast +}$ momentum direction in the pp centre of mass frame. The ${\rho }_{00}$ value for prompt ${\mathrm{D}}^{\ast +}$ mesons is consistent with $1/3$, which implies no spin alignment. However, for non-prompt ${\mathrm{D}}^{\ast +}$ mesons an evidence of ${\rho }_{00}$ larger than $1/3$ is found. The measured value of the spin density element is ${\rho }_{00}=0.455\pm 0.022(\text{stat.})\pm 0.035(\text{syst.})$ in the $5<p_{\mathrm{T}}<20$ GeV/$c$ interval, which is consistent with a PYTHIA 8 Monte Carlo simulation coupled with the EVTGEN package, which implements the helicity conservation in the decay of ${\mathrm{D}}^{\ast +}$ meson from beauty mesons. In non-central heavy-ion collisions, the spin of the ${\mathrm{D}}^{\ast +}$ mesons may be globally aligned with the direction of the initial angular momentum and magnetic field. Based on the results for pp collisions reported in this letter it is shown that alignment of non-prompt ${\mathrm{D}}^{\ast +}$ mesons due to the helicity conservation coupled to the collective anisotropic expansion may mimic the signal of global spin alignment in heavy-ion collisions.

   nucl-exhep-exPLB(2023)·15 citations
4. 04*

   High accuracy synchrotron radiation interferometry with relativistic electrons

   P. Klag🇩🇪 · P. Achenbach🇩🇪 · T. Akiyama🇯🇵 · R. Böhm🇩🇪 · M.O. Distler🇩🇪 · L. Doria🇩🇪 · P. Eckert🇩🇪 · A. Esser🇩🇪 · J. Geratz🇩🇪 · T. Gogami🇯🇵 · C. Helmel · P. Herrmann🇩🇪 and 19 other authors

   A high-precision hypernuclear experiment has been performed at the Mainz Microtron (MAMI) to determine the hypertriton {\Lambda} binding energy via decay-pion spectroscopy. A key element of this measurement is an accurate calibration of the magnetic spectrometers with the MAMI beam. For such an absolute calibration with small statistical and systematic uncertainties the undulator light interference method will be applied. In this contribution the basic principle of this method is discussed and the analysis status of the measured synchrotron radiation spectra is presented

   ↳ physics.ins-detnucl-exphysics.acc-phJ.Phys.Conf.Ser.(2023)·2 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.