Mon·Jul 25, 2022Monday·July 25, 2022

1. 01*

   Measurement of $\varphi$-meson production in Cu$+$Au at $\sqrt{s_{{}_{NN}}}=200$ GeV and U$+$U at $\sqrt{s_{{}_{NN}}}=193$ GeV

   N.J. Abdulameer · U. Acharya · C. Aidala · N.N. Ajitanand · Y. Akiba · R. Akimoto · J. Alexander · M. Alfred · M. Alibordi · K. Aoki · N. Apadula · H. Asano and 401 other authors

   The PHENIX experiment reports systematic measurements at the Relativistic Heavy Ion Collider of $\varphi$-meson production in asymmetric Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV and in U$+$U collisions at $\sqrt{s_{{}_{NN}}}$=193 GeV. Measurements were performed via the $\varphi \to K^{+}{K}^{-}$ decay channel at midrapidity $|\eta |<0.35$. Features of $\varphi$-meson production measured in Cu$+$Cu, Cu$+$Au, Au$+$Au, and U$+$U collisions were found to not depend on the collision geometry, which was expected because the yields are averaged over the azimuthal angle and follow the expected scaling with nuclear-overlap size. The elliptic flow of the $\varphi$ meson in Cu$+$Au, Au$+$Au, and U$+$U collisions scales with second-order-participant eccentricity and the length scale of the nuclear-overlap region (estimated with the number of participating nucleons). At moderate $p_T$, $\varphi$-meson production measured in Cu$+$Au and U$+$U collisions is consistent with coalescence-model predictions, whereas at high $p_T$ the production is in agreement with expectations for in-medium energy loss of parent partons prior to their fragmentation. The elliptic flow for $\varphi$ mesons measured in Cu$+$Au and U$+$U collisions is well described by a (2+1)D viscous-hydrodynamic model with specific-shear viscosity $\eta /s=1/4\pi$.

   nucl-exPRC(2023)·18 citations
2. 02*

   Strange Hadron Spectroscopy with the KLong Facility at Jefferson Lab

   Sean Dobbs (For the KLF Collaboration)🇺🇸

   The strange quark hadrons sit at an important crossroads between the light and heavy quark hadrons, but their spectrum is comparatively poorly known. The KLF experiment was recently approved to run in Hall D of Jefferson Lab, and will use an intense secondary beam of $K_L$ mesons with the existing GlueX spectrometer to collect data several orders of magnitude larger than existing dataset. In this talk, I will discuss the expected physics reach of this experiment and the status of its preparations.

   nucl-exRev.Mex.Fis.Suppl.(2022)·8 citations
3. 03*

   Study of elastic and inelastic scattering of ${}^7$Be + ${}^{12}$C at 35 MeV

   K. Kundalia🇮🇳 · D. Gupta🇮🇳 · Sk M. Ali🇮🇳 · Swapan K Saha🇮🇳 · O. Tengblad🇪🇸 · J.D. Ovejas🇪🇸 · A. Perea🇪🇸 · I. Martel🇪🇸 · J. Cederkall🇸🇪 · J. Park🇸🇪 · S. Szwec🇫🇮 · A. M. Moro🇪🇸

   The elastic and inelastic scattering of ${}^7$Be from ${}^{12}$C have been measured at an incident energy of 35 MeV. The inelastic scattering leading to the 4.439 MeV excited state of ${}^{12}$C has been measured for the first time. The experimental data cover an angular range of ${\theta }_{cm}$ = 15${}^{\circ }$-120${}^{\circ }$. Optical model analyses were carried out with Woods-Saxon and double-folding potential using the density dependent M3Y (DDM3Y) effective interaction. The microscopic analysis of the elastic data indicates breakup channel coupling effect. A coupled-channel analysis of the inelastic scattering, based on collective form factors, show that mutual excitation of both ${}^7$Be and ${}^{12}$C is significantly smaller than the single excitation of ${}^{12}$C. The larger deformation length obtained from the DWBA analysis could be explained by including the excitation of ${}^7$Be in a coupled-channel analysis. The breakup cross section of ${}^7$Be is estimated to be less than 10$\%$ of the reaction cross section. The intrinsic deformation length obtained for the ${}^{12}$C${}^{\ast }$ (4.439 MeV) state is ${\delta }_2$ = 1.37 fm. The total reaction cross section deduced from the analysis agrees very well with Wong's calculations for similar weakly bound light nuclei on ${}^{12}$C target.

   nucl-exnucl-thPLB(2022)·19 citations
4. 04*

   The use of a novel gradient heat flux sensor for characterization of reflux condensation

   Filip Janasz · Horst-Michel Prasser · Detlef Suckow · Andrey Mityakov

   In this paper we present the developments in heat flux measurements using gradient heat flux sensors (GHFS). The GHFS is a sensor made of artificially created material with anisotropic thermo-electrical properties. Its properties including small size, robustness and low response time make it a valuable addition for characterizing heat flux in space-limited geometries as well as harsh environmental conditions. This makes it ideal for investigation of reflux condensation in the steam generator tubes of a pressurized water reactor. The reflux condenser mode of operation during accident as well as maintenance conditions can provide a significant passive cooling, removing the residual decay heat from the reactor core, thus preventing or at least delaying potential core uncovery. With this novel implementation of GHFS deeper characterization of heat flux during reflux condensation was achieved.

   nucl-exNucl.Eng.Des.(2022)·0 citations
5. 05*

   Interpretable Boosted Decision Tree Analysis for the Majorana Demonstrator

   I. J. Arnquist🇺🇸 · F. T. Avignone III🇺🇸 · A. S. Barabash🇷🇺 · C. J. Barton🇺🇸 · K. H. Bhimani🇺🇸 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · M. Buuck🇺🇸 · T. S. Caldwell🇺🇸 · Y -D. Chan🇺🇸 · C. D. Christofferson🇺🇸 and 43 other authors

   The Majorana Demonstrator is a leading experiment searching for neutrinoless double-beta decay with high purity germanium detectors (HPGe). Machine learning provides a new way to maximize the amount of information provided by these detectors, but the data-driven nature makes it less interpretable compared to traditional analysis. An interpretability study reveals the machine's decision-making logic, allowing us to learn from the machine to feedback to the traditional analysis. In this work, we have presented the first machine learning analysis of the data from the Majorana Demonstrator; this is also the first interpretable machine learning analysis of any germanium detector experiment. Two gradient boosted decision tree models are trained to learn from the data, and a game-theory-based model interpretability study is conducted to understand the origin of the classification power. By learning from data, this analysis recognizes the correlations among reconstruction parameters to further enhance the background rejection performance. By learning from the machine, this analysis reveals the importance of new background categories to reciprocally benefit the standard Majorana analysis. This model is highly compatible with next-generation germanium detector experiments like LEGEND since it can be simultaneously trained on a large number of detectors.

   ↳ physics.data-ancs.LGnucl-exPRC(2023)·11 citations
6. 06*

   Improved FIFRELIN de-excitation model for neutrino applications

   H. Almazan (1)🇩🇪 · L. Bernard (2)🇫🇷 · A. Blanchet (3)🇫🇷 · A. Bonhomme (3)🇩🇪 · C. Buck (1)🇩🇪 · A. Chalil (3)🇫🇷 · A. Chebboubi (4)🇫🇷 · P. del Amo Sanchez (5)🇫🇷 · I. El Atmani (3)🇫🇷 · L. Labit (5)🇫🇷 · J. Lamblin (2)🇫🇷 · A. Letourneau (3)🇫🇷 and 17 other authors

   The precise modeling of the de-excitation of Gd isotopes is of great interest for experimental studies of neutrinos using Gd-loaded organic liquid scintillators. The FIFRELIN code was recently used within the purposes of the STEREO experiment for the modeling of the Gd de-excitation after neutron capture in order to achieve a good control of the detection efficiency. In this work, we report on the recent additions in the FIFRELIN de-excitation model with the purpose of enhancing further the de-excitation description. Experimental transition intensities from EGAF database are now included in the FIFRELIN cascades, in order to improve the description of the higher energy part of the spectrum. Furthermore, the angular correlations between {\gamma} rays are now implemented in FIFRELIN, to account for the relative anisotropies between them. In addition, conversion electrons are now treated more precisely in the whole spectrum range, while the subsequent emission of X rays is also accounted for. The impact of the aforementioned improvements in FIFRELIN is tested by simulating neutron captures in various positions inside the STEREO detector. A repository of up-to-date FIFRELIN simulations of the Gd isotopes is made available for the community, with the possibility of expanding for other isotopes which can be suitable for different applications.

   ↳ hep-exnucl-exEPJA(2023)·6 citations
7. 07*

   Ab initio calculation of the $\beta$ decay spectrum of ${}^6$He

   Garrett B. King🇺🇸 · Alessandro Baroni🇺🇸 · Vincenzo Cirigliano🇺🇸 · Stefano Gandolfi🇺🇸 · Leendert Hayen🇺🇸 · Emanuele Mereghetti🇺🇸 · Saori Pastore🇺🇸 · Maria Piarulli🇺🇸

   We calculate the $\beta$ spectrum in the decay of ${}^6$He using Quantum Monte Carlo methods with nuclear interactions derived from chiral Effective Field Theory and consistent weak vector and axial currents. We work at second order in the multipole expansion, retaining terms suppressed by $\mathcal{O}(q^2/m_{\pi }^2)$, where $q$ denotes low-energy scales such as the reaction's $\mathcal{Q}$-value or the electron energy, and $m_{\pi }$ the pion mass. We go beyond the impulse approximation by including the effects of two-body vector and axial currents. We estimate the theoretical error on the spectrum by using four potential models in the Norfolk family of local two- and three-nucleon interactions, which have different cut-off, fit two-nucleon data up to different energies and use different observables to determine the couplings in the three-body force. We find the theoretical uncertainty on the $\beta$ spectrum, normalized by the total rate, to be well below the permille level, and to receive contributions of comparable size from first and second order corrections in the multipole expansion. We consider corrections to the $\beta$ decay spectrum induced by beyond-the-Standard Model charged-current interactions in the Standard Model Effective Field Theory, with and without sterile neutrinos, and discuss the sensitivity of the next generation of experiments to these interactions.

   ↳ nucl-thhep-phnucl-exPRC(2023)·36 citations
8. 08*

   Machine Learned Particle Detector Simulations

   D. Darulis🇬🇧 · R. Tyson🇬🇧 · D. G. Ireland🇬🇧 · D. I. Glazier🇬🇧 · B. McKinnon🇬🇧 · P. Pauli🇬🇧

   The use of machine learning algorithms is an attractive way to produce very fast detector simulations for scattering reactions that can otherwise be computationally expensive. Here we develop a factorised approach where we deal with each particle produced in a reaction individually: first determine if it was detected (acceptance) and second determine its reconstructed variables such as four momentum (reconstruction). For the acceptance we propose using a probability classification density ratio technique to determine the probability the particle was detected as a function of many variables. Neural Network and Boosted Decision Tree classifiers were tested for this purpose and we found using a combination of both, through a reweighting stage, provided the most reliable results. For reconstruction a simple method of synthetic data generation, based on nearest neighbour or decision trees was developed. Using a toy parameterised detector we demonstrate that such a method can reliably and accurately reproduce kinematic distributions from a physics reaction. The relatively simple algorithms allow for small training overheads whilst producing reliable results. Possible applications for such fast simulated data include Toy-MC studies of parameter extraction, preprocessing expensive simulations or generating templates for background distributions shapes.

   ↳ physics.data-anhep-exnucl-ex7 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.