Tue·Feb 1, 2022Tuesday·February 1, 2022

1. 01*

   High-precision electron-capture $Q$ value measurement of ${}^{111}$In for electron-neutrino mass determination

   Z.Ge🇫🇮 · T.Eronen🇫🇮 · A.deRoubin🇫🇷 · K.S.Tyrin🇷🇺 · L.Canete🇬🇧 · S.Geldhof🇫🇮 · A.Jokinen🇫🇮 · A. Kankainen🇫🇮 · J. Kostensalo🇫🇮 · J. Kotila🇫🇮 · M. I. Krivoruchenko🇷🇺 · I. D. Moore🇫🇮 and 3 other authors

   A precise determination of the ground state ${}^{111}$In ($9/2^{+}$) electron capture to ground state of ${}^{111}$Cd ($1/2^{+}$) $Q$ value has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. A value of 857.63(17) keV was obtained, which is nearly a factor of 20 more precise than the value extracted from the Atomic Mass Evaluation 2020 (AME2020). The high-precision electron-capture $Q$ value measurement along with the nuclear energy level data of 866.60(6) keV, 864.8(3) keV, 855.6(10) keV, and 853.94(7) keV for ${}^{111}$Cd was used to determine whether the four states are energetically allowed for a potential ultra-low $Q$-value ${\beta }^{}$ decay or electron-capture decay. Our results confirm that the excited states of 866.60(6) keV with spin-parity ($J^{\pi }$) of 3/2${}^{+}$ and 864.8(3) keV with $J^{\pi }$ = 3/2${}^{+}$ are ruled out due to their deduced electron-capture $Q$ value being smaller than 0 keV at the level of around 20$\sigma$ and 50$\sigma$, respectively. Electron-capture decays to the excited states at 853.94(7) keV ($J^{\pi }$ = 7/2${}^{+}$) and 855.6(10) keV ($J^{\pi }$ = 3/2${}^{+}$), are energetically allowed with $Q$ values of 3.69(19) keV and 2.0(10) keV, respectively. The allowed decay transition ${}^{111}$In (9/2${}^{+}$) $\to$ ${}^{111}$Cd (7/2${}^{+}$), with a $Q$ value of 3.69(19) keV, is a potential a new candidate for neutrino-mass measurements by future EC experiments featuring new powerful detection technologies. The results show that the indium level $2p_{1/2}$ for this decay branch leads to a significant increase in the number of EC events in the energy region sensitive to the electron neutrino mass.

   nucl-exPLB(2022)·15 citations
2. 02*

   An overview of recent STAR jet measurements

   Nihar Ranjan Sahoo (for the STAR collaboration)🇨🇳

   These proceedings discuss recent jet measurements by the STAR experiment at RHIC to study jet substructure in p+p and jet quenching in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV. Furthermore, STAR's future plans for precision jet measurements with the upcoming data-taking periods in 2023-2025 are presented.

   nucl-exhep-exhep-phnucl-thIJMPE(2024)·0 citations
3. 03*

   Production of strange hadrons in jets and underlying events in pp and p-Pb collisions with ALICE

   Pengyao Cui (for the ALICE Collaboration)🇨🇳

   The production of strange~($K_S^0$, $\Lambda$) and multi-strange~($\Xi$ and $\Omega$) hadrons in jets and underlying events in \pp and \pPb collisions is studied with ALICE at the LHC. Transverse momentum (p_\rm{T}) differential density distribution of particles produced in a jet is compared to that of inclusive particle production and that in underlying events. The particle yield ratios of $\Lambda /K_S^0$ and $\Xi /\Lambda$ as a function of p_\rm{T} are also investigated in jets and underlying events.The production of the multi-strange hadrons, $\Xi$ and $\Omega$, and the corresponding ratio in jets and underlying events are measured for the first time. The p_\rm{T}-differential density distribution of hadrons associated with hard scattering decreases slower than that for inclusive production. The baryon-to-meson and baryon-to-baryon ratios measured in jets exhibit clear differences from values obtained from the inclusive spectra in the intermediate p_\rm{T} range. The p_\rm{T} distribution of strange hadrons produced in jets is also studied in pp collisions at $\sqrt{s}$ = 13 TeV and 7 TeV and in p-Pb collisions at \sqrt{s_\rm{NN}} = 5.02 TeV. The p_\rm{T} spectra of particle produced in jets are independent of collision systems and collision energies.No apparent collision energy and collision system dependence is observed for the particle yield ratios of $\Lambda /K_S^0$ and $\Xi /\Lambda$ associated with energetic jets. These new results are compared to PYTHIA 8 event generator. The $\Lambda /K_S^0$ ratio are generally reproduced by the model, but large discrepancies between data and PYTHIA simulations are observed for $\Xi /\Lambda$.

   ↳ hep-exnucl-exPhys.Scripta(2022)·2 citations
4. 04*

   Bayesian reconstruction of impact parameter distributions from two observables for intermediate energy heavy ion collisions

   Xiang Chen🇨🇳 · Li Li🇨🇳 · Ying Cui🇨🇳 · Junping Yang🇨🇳 · Zhuxia Li🇨🇳 · Yingxun Zhang🇨🇳

   To reconstruct the impact parameter distributions from the selected events sample or centrality, which is defined by two-observables, at intermediate energy heavy ion collisions, we extend the approach proposed by Das \textit{et al.} [Phys. Rev. C 97, 014905 (2018)], Rogly \textit{et al.} [Phys. Rev. C 98, 024902 (2018)], and Frankland \textit{et al.} [Phys. Rev. C 104, 034609 (2021)]. Based on deep investigations of the fluctuation mechanism, we found that the intrinsic fluctuations are mainly generated in the microscopic stochasticity of initialization and nucleon-nucleon collisions in the nonequilibrium process of heavy ion collisions, and this leads the observables to fluctuate with respect to impact parameter in a Gaussian form. In this work, the multiplicity of the charged particles and the total transverse momentum of the light charged particles are used simultaneously to model-independently reconstruct the impact parameter distributions for selected events or centrality based on the Bayesian method. For sorting the centrality with two observables, we propose to use the $K$-means clustering method (an unsupervised machine learning algorithm), which can automatically sort events when the class number is given. Furthermore, the reconstructed impact parameter distributions from data of the two observables can be used to learn the correlation between multiplicity and transverse momentum at different centralities, which may be useful for understanding the fragmentation mechanism.

   ↳ nucl-thnucl-exPRC(2023)·12 citations
5. 05*

   Backward timelike Compton scattering to decipher the photon content of the nucleon

   Bernard Pire🇫🇷 · Kirill M. Semenov-Tian-Shansky🇷🇺 · Alisa A. Shaikhutdinova🇷🇺 · Lech Szymanowski🇵🇱

   The exclusive photoproduction off nucleon of a large invariant mass lepton pair in the backward region specified by the small Mandelstam variable $-u$ is discussed in the framework of collinear QCD factorization. The amplitude is factorized in terms of photon-to-nucleon Transition Distribution Amplitudes (TDAs) which encode the photon content of the nucleon. Model estimates of these new non-perturbative objects are described and the corresponding cross sections calculated. The background due to the electromagnetic Bethe-Heitler process is shown to be negligible in the kinematical regime of interest.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2022)·11 citations
6. 06*

   Effect of Magnetic Field Dissipation on Primordial Li Abundance

   Yini Lu · Motohiko Kusakabe🇨🇳

   The dissipation effects of primordial magnetic fields on the primordial elemental abundances were investigated. When a magnetic field reconnects, its energy is converted to the kinetic energy of charged particles, as observed for solar energetic particles arriving on earth. This accelerates the cosmic background nuclei, and energetic nuclei induce nonthermal reactions. A constraint on the dissipation is derived from a theoretical calculation of the nonthermal reactions during Big Bang nucleosynthesis. We found that observations of the Li and D abundances can be explained if 0.01--0.1 % of the cosmic energy density was utilized for nuclear acceleration after the electron--positron annihilation epoch. Reconnections of such amplitudes of magnetic fields generate outgoing jets, the bulk velocity of which evolves to values appropriate for cosmic ray (CR) nuclear energies of 0.1--1 MeV necessary for successful CR nucleosynthesis. Therefore, acceleration of cosmic background nuclei during the dissipation of primordial magnetic fields is a possible generation mechanism of soft CRs that has been suggested as a solution to the cosmic Li problem. Among the solutions suggested without exotic physics, only the dissipating magnetic field model suggested here explains observations of both low Li and high D abundances. Our results demonstrate that signatures of strong magnetic fields in the early universe have been observed in primordial elemental abundances.

   ↳ astro-ph.COastro-ph.HEhep-phnucl-exApJL(2022)·4 citations
7. 07*

   A high-density polarized 3He gas-jet target for laser-plasma applications

   P. Fedorets🇩🇪 · C. Zheng🇺🇸 · R. Engels🇩🇪 · I. Engin · H. Feilbach · U. Giesen · H. Glückler · C. Kannis · F. Klehr🇩🇪 · M. Lennartz · H. Pfeifer · J. Pfennings and 5 other authors

   A laser-driven spin-polarized 3He2+ beam source for nuclear-physics experiments and for the investigation of polarized nuclear fusion demands a high-density polarized 3He gas-jet target. Such a target requires a magnetic system providing a permanent homogeneous holding field for the nuclear spins plus a set of coils for adjusting the orientation of the polarization. Starting from a transport vessel at a maximum pressure of 3 bar, the helium gas is compressed for a short time and can be injected into a laser-interaction chamber through a non-magnetic opening valve and nozzle, thus forming jets with densities of about a few 10^19 cm-3 and widths of about 1 mm. The target comprises a 3D adjustment system for precise positioning of the jet relative to the laser focus. An auxiliary gas system provides remote target operation and flushing of the gas lines with Ar gas, which helps to reduce polarization losses. The design of the target, its operation procedures and first experimental results are presented.

   ↳ physics.ins-detnucl-exInstruments(2022)·9 citations
8. 08*

   Towards machine learning aided real-time range imaging in proton therapy

   Jorge Lerendegui-Marco (1) · Javier Balibrea-Correa (1)🇪🇸 · Víctor Babiano-Súarez (1)🇪🇸 · Ion Ladarescu (1)🇪🇸 · César Domingo-Pardo (1) ((1) Instituto de Física Corpuscular, CSIC-University of Valencia, Valencia, Spain)🇪🇸

   In this work, we report on the advantageous aspects of the i-TED Compton imager for proton-range monitoring, based on the results of the first Monte Carlo study of its applicability to this field. i-TED is an array of Compton cameras, that have been designed for neutron-capture nuclear physics experiments, which are characterized by $\gamma$-ray energies spanning up to 5-6 MeV, rather low $\gamma$-ray emission yields and intense neutron induced $\gamma$-ray backgrounds. Our developments to cope with these three aspects are concomitant with those required in the field of hadron therapy, especially in terms of high efficiency for real-time monitoring, low sensitivity to neutron backgrounds and reliable performance at the high $\gamma$-ray energies. We find that signal-to-background ratios can be appreciably improved with i-TED thanks to its light-weight design and the low neutron-capture cross sections of its LaCl${}_3$ crystals, when compared to other similar systems based on LYSO, CdZnTe or LaBr${}_3$. Its high time-resolution (CRT$\sim$500 ps) represents an additional advantage for background suppression when operated in pulsed HT mode. Each i-TED module features two detection planes of very large LaCl${}_3$ monolithic crystals, thereby achieving a high efficiency in coincidence of 0.2% for a point-like 1MeV $\gamma$-ray source at 5 cm distance. This leads to sufficient statistics for reliable image reconstruction with an array of four i-TED detectors assuming clinical intensities of 10${}^8$ protons per treatment point. The use of a two-plane design instead of three-planes has been preferred owing to the higher attainable efficiency for double time-coincidences than for threefold events. The loss of full-energy events for high energy $\gamma$-rays is compensated by means of Machine-Learning algorithms, which allow one to enhance the signal-to-total ratio up to a factor of 2.

   ↳ physics.med-phnucl-exphysics.ins-detSci.Rep.(2022)·9 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.