Tue·Mar 7, 2023Tuesday·March 7, 2023

1. 01*

   First measurement of the nuclear-recoil ionization yield in silicon at 100 eV

   M.F. Albakry · I. Alkhatib · D. Alonso · D.W.P. Amaral · P. An · T. Aralis · T. Aramaki · I.J. Arnquist · I. Ataee Langroudy · E. Azadbakht · S. Banik · P.S. Barbeau and 128 other authors

   We measured the nuclear--recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a mono-energetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4\,keV down to 100\,eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100\,eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale.

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exPRL(2023)·38 citations
2. 02*

   The Present and Future of QCD

   P. Achenbach · D. Adhikari · A. Afanasev · F. Afzal · C.A. Aidala · A. Al-bataineh · D.K. Almaalol · M. Amaryan · D. Androić · W.R. Armstrong · M. Arratia · J. Arrington and 391 other authors

   This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research.

   ↳ hep-phhep-exnucl-exnucl-thNPA(2024)·135 citations
3. 03*

   Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics

   K. Pomorski🇵🇱 · B. Nerlo-Pomorska🇵🇱 · C. Schmitt🇫🇷 · Z.G. Xiao🇨🇳 · Y. J. Chen🇨🇳 · L.L. Liu🇨🇳

   We propose a new, rapidly convergent, the so-called Fourier over Spheroid (FoS), shape parametrization to model fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system, being its elongation, left-right asymmetry, neck size, and non-axiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on the top of which the multi-dimensional Langevin equation is solved to describe the dynamics. Charge equilibration at scission and de-excitation of the primary fragments after scission are further considered. The model gives access to a wide variety of observables, including fission fragments mass, charge, and kinetic energy yields, fragment mean N/Z and post-scission neutron multiplicities, and importantly, their correlations. The latter are crucial to unravel the complexity of the fission process. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of 235U, and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain.

   ↳ nucl-thnucl-exPRC(2023)·20 citations
4. 04*

   Description of inclusive $(d,d^{\prime }x)$ reaction with the semiclassical distorted wave model

   Hibiki Nakada · Kazuki Yoshida🇯🇵 · Kazuyuki Ogata🇯🇵

   The description of deuteron-induced inclusive reactions has been an important subject in direct nuclear reaction studies and nuclear data science. For proton-induced inclusive processes, the semiclassical distorted wave model (SCDW) is one of the most successful models based on quantum mechanics. We improve SCDW for deuteron-induced inclusive processes and clarify the importance of the proper treatment of the kinematics of the deuteron inside a nucleus. The double differential cross section (DDX) of the inclusive deuteron-emission process $(d,d^{\prime }x)$ is described by one-step SCDW. The changes in the kinematics due to the distortion effect, the refraction effect, is taken into account by the local semiclassical approximation (LSCA). The calculated DDXs of $(d,d^{\prime }x)$ reasonably reproduce experimental data in the small energy-transfer region and at forward and middle angles with some exceptions. The angular distributions of $(d,d^{\prime }x)$ are improved by including the refraction effect. The proper treatment of the changes in the kinematics of the deuteron inside a nucleus is necessary in describing the ($d$,$d^{\prime }x$) reaction. The effect of the changes on the DDX of $(d,d^{\prime }x)$ is significant compared to on the proton-induced inclusive process $(p,p^{\prime }x)$ because of the stronger distortion effect on the deuteron.

   ↳ nucl-thnucl-exPRC(2023)·4 citations
5. 05*

   Characterization of the performances of plastic commercial scintillators in cryogenic environments

   M. Biassoni🇮🇹 · A. Caminata🇮🇹 · S. Caprioli🇮🇹 · A. Celentano🇮🇹 · S. Davini🇮🇹 · A. Marini🇮🇹 · G. Sobrero🇮🇹

   Plastic scintillators have become increasingly important in particle physics for time-of-flight and calorimetry measurements. Their light yield and the possibility of customizing their geometry make them also attractive for the construction of active vetoes in rare event physics experiments. For this purpose, some commercial plastic scintillators (purchased from Eljen Technology) were tested in cryogenic environments (liquid nitrogen and liquid helium). Their relative light yield was estimated by comparing the data acquired at room temperature with those acquired at cryogenic temperatures. Finally, estimates of the variation of the light yield at cryogenic temperatures were obtained.

   ↳ physics.ins-detnucl-exJINST(2023)·0 citations
6. 06*

   Generalized Method for the Optimization of Pulse Shape Discrimination Parameters

   Jianxin Zhou · Abdullah Abdulaziz · Yoann Altmann · Angela Di Fulvio

   Organic scintillators exhibit fast timing, high detection efficiency for fast neutrons and pulse shape discrimination (PSD) capability. PSD is essential in mixed radiation fields, where different types of radiation need to be detected and discriminated. In neutron measurements for nuclear security and non proliferation effective PSD is crucial, because a weak neutron signature needs to be detected in the presence of a strong gamma-ray background. The most commonly used deterministic PSD technique is charge integration (CI). This method requires the optimization of specific parameters to obtain the best gamma-neutron separation. These parameters depend on the scintillating material and light readout device and typically require a lengthy optimization process and a calibration reference measurement with a mixed source. In this paper, we propose a new method based on the scintillation fluorescence physics that enables to find the optimum PSD integration gates using only a gamma-ray emitter. We demonstrate our method using three organic scintillation detectors: deuterated trans-stilbene, small-molecule organic glass, and EJ-309. In all the investigated cases, our method allowed finding the optimum PSD CI parameters without the need of iterative optimization.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2023)·1 citation
7. 07*

   A Coherent View of the Quark-Gluon Plasma from Energy Correlators

   Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸 · Jack Holguin🇫🇷 · Cyrille Marquet🇫🇷 · Ian Moult🇺🇸

   The ability to measure detailed aspects of the substructure of high-energy jets traversing the quark-gluon plasma (QGP) has provided a new window into its internal dynamics. However, drawing robust conclusions from traditional jet substructure observables has been difficult. In this manuscript we expand on a new approach to jet substructure in heavy-ion collisions based on the study of correlation functions of energy flow operators (energy correlators). We compute the two-point energy correlator of an in-medium massless quark jet and perform a detailed numerical analysis of the produced spectra. Our calculation incorporates vacuum radiation resummed at next-to-leading log accuracy together with the leading order contribution in medium-induced splittings evaluated through the BDMPS-Z multiple scattering and GLV single scattering formalisms for a static brick of QGP. Our analysis demonstrates how particular features of the modifications of in-medium splittings are imprinted in the correlator spectra, particularly showing how energy correlators may be used to extract the onset of colour coherence. We further present a comprehensive discussion on the accuracy and limitations of our study emphasizing how it can be systematically improved. This work sets the foundations for a rich program studying energy correlators in heavy-ion collisions.

   ↳ hep-phhep-exhep-thnucl-ex+1JHEP(2023)·98 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.