Thu·Jun 25, 2020Thursday·June 25, 2020

1. 01*

   Observation of a $\bar{K}NN$ bound state in the ${}^3\mathrm{He}(K^{-},\Lambda p)n$ reaction

   T. Yamaga🇯🇵 · S. Ajimura🇯🇵 · H. Asano🇯🇵 · G. Beer🇨🇦 · H. Bhang🇰🇷 · M. Bragadireanu🇷🇴 · P. Buehler🇦🇹 · L. Busso🇮🇹 · M. Cargnelli🇦🇹 · S. Choi🇰🇷 · C. Curceanu🇮🇹 · S. Enomoto🇯🇵 and 57 other authors

   We have performed an exclusive measurement of the $K^{-}+{}^3\mathrm{He}\to \Lambda pn$ reaction at an incident kaon momentum of $1\mathrm{GeV}/c$.In the $\Lambda p$ invariant mass spectrum, a clear peak was observed below the mass threshold of $\bar{K}+N+N$, as a signal of the kaonic nuclear bound state, $\bar{K}NN$.The binding energy, decay width, and $S$-wave Gaussian reaction form-factor of this state were observed to be $B_K=42\pm 3(stat.{)}_{-4}^{+3}(syst.)\mathrm{MeV}$, ${\Gamma }_K=100\pm 7(stat.{)}_{-9}^{+19}(syst.)\mathrm{MeV}$, and $Q_K=383\pm 11(stat.{)}_{-1}^{+4}(syst.)\mathrm{MeV}/c$, respectively. The total production cross-section of $\bar{K}NN$, determined by its $\Lambda p$ decay mode, was ${\sigma }_K^{tot}\cdot B{R}_{\Lambda p}=9.3\pm 0.8(stat.{)}_{-1.0}^{+1.4}(syst.)\mu \mathrm{b}$.We estimated the branching ratio of the $\bar{K}NN$ state to the $\Lambda p$ and ${\Sigma }^{0}p$ decay modes as $B{R}_{\Lambda p}/B{R}_{{\Sigma }^{0}p}\sim 1.7$, by assuming that the physical processes leading to the $\Sigma NN$ final states are analogous to those of $\Lambda pn$.

   nucl-exPRC(2020)·53 citations
2. 02*

   Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at $\sqrt{{\text{s}}_{NN}}$ = 200 GeV

   STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 · E. C. Aschenauer🇺🇸 · M. U. Ashraf🇨🇳 and 352 other authors

   Flow harmonics (${\text{v}}_n$) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (${\text{v}}_2$ and ${\text{v}}_3$) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (${\text{v}}_{n>3}$) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy $\sqrt{{\text{s}}_{NN}}$ = 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.

   nucl-exPLB(2020)·17 citations
3. 03*

   Evaluation of the ${}^{13}$N($\alpha$,p)${}^{16}$O thermonuclear reaction rate and its impact on the isotopic composition of supernova grains

   A. Meyer🇫🇷 · N. de Séréville🇫🇷 · A. M. Laird🇬🇧 · F. Hammache🇫🇷 · R. Longland🇺🇸 · T. Lawson🇬🇧 · M. Pignatari🇬🇧 · L. Audouin🇫🇷 · D. Beaumel🇫🇷 · S. Fortier🇫🇷 · J. Kiener🇫🇷 · A. Lefebvre-Schuhl🇫🇷 and 3 other authors

   It has been suggested that hydrogen ingestion into the helium shell of massive stars could lead to high ${}^{13}$C and ${}^{15}$N excesses when the shock of a core-collapse supernova passes through its helium shell. This prediction questions the origin of extremely high ${}^{13}$C and ${}^{15}$N abundances observed in rare presolar SiC grains which is usually attributed to classical novae. In this context ${}^{13}$N($\alpha$,p)${}^{16}$O the reaction plays an important role since it is in competition with ${}^{13}$N ${\beta }^{+}$-decay to ${}^{13}$C. The ${}^{13}$N($\alpha$,p)${}^{16}$O reaction rate used in stellar evolution calculations comes from the CF88 compilation with very scarce information on the origin of this rate. The goal of this work is to provide a recommended ${}^{13}$N($\alpha$,p)${}^{16}$O reaction rate, based on available experimental data. Unbound nuclear states in the ${}^{17}$F compound nucleus were studied using the spectroscopic information of the analog states in ${}^{17}$O nucleus that were measured at the Alto facility using the ${}^{13}$C(${}^7$Li,t)${}^{17}$O alpha-transfer reaction, and spectroscopic factors were derived using a DWBA analysis. This spectroscopic information was used to calculate a recommended ${}^{13}$N($\alpha$,p)${}^{16}$O reaction rate with meaningful uncertainty using a Monte Carlo approach. The present ${}^{13}$N($\alpha$,p)${}^{16}$O reaction rate is found to be within a factor of two of the previous evaluation, with a typical uncertainty of a factor 2-3. The source of this uncertainty comes from the three resonances at $E_r^{c.m.}=221$, 741 and 959 keV. This new error estimation translates to an overall uncertainty in the ${}^{13}$C production of a factor of 50. The main source of uncertainty on the re-evaluated ${}^{13}$N($\alpha$,p)${}^{16}$O reaction rate currently comes from the uncertain alpha-width of relevant ${}^{17}$F states.

   nucl-exastro-ph.SRPRC(2020)·9 citations
4. 04*

   Probing the structure of the initial state of heavy-ion collisions with $p_T$-dependent flow fluctuations

   Maurício Hippert🇧🇷 · João Guilherme Prado Barbon🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Matthew Luzum🇧🇷 · Jorge Noronha🇺🇸 · Tiago Nunes da Silva🇧🇷 · Willian Matioli Serenone🇧🇷 · Jun Takahashi🇧🇷

   The connection between initial-state geometry and anisotropic flow can be quantified through a well-established mapping between $p_T$-integrated flow harmonics and cumulants of the initial transverse energy distribution. In this paper we successfully extend this mapping to also include $p_T$-differential flow. In doing so, we find that subleading principal components of anisotropic flow can reveal previously unobserved details of the hydrodynamic response, in both the linear and the nonlinear regimes. Most importantly, we show that they provide novel information on the small-scale structures present in the initial stage of relativistic heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exPRC(2020)·13 citations
5. 05*

   Characterization of a Silicon Drift Detector for High-Resolution Electron Spectroscopy

   Matteo Gugiatti🇮🇹 · Matteo Biassoni🇮🇹 · Marco Carminati · Oliviero Cremonesi🇮🇹 · Carlo Fiorini🇮🇹 · Pietro King🇮🇹 · Peter Lechner🇩🇪 · Susanne Mertens🇩🇪 · Lorenzo Pagnanini🇮🇹 · Maura Pavan🇮🇹 · Stefano Pozzi🇮🇹

   Silicon Drift Detectors, widely employed in high-resolution and high-rate X-ray applications, are considered here with interest also for electron detection. The accurate measurement of the tritium beta decay is the core of the TRISTAN (TRitium Investigation on STerile to Active Neutrino mixing) project. This work presents the characterization of a single-pixel SDD detector with a mono-energetic electron beam obtained from a Scanning Electron Microscope. The suitability of the SDD to detect electrons, in the energy range spanning from few keV to tens of keV, is demonstrated. Experimental measurements reveal a strong effect of the detector's entrance window structure on the observed energy response. A detailed detector model is therefore necessary to reconstruct the spectrum of an unknown beta-decay source.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·23 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.