Wed·Mar 23, 2022Wednesday·March 23, 2022

1. 01*

   Photonuclear reactions ${}^{nat}$Ni($\gamma$,xn)${}^{57}$Ni and ${}^{nat}$Ni($\gamma$,xn)${}^{56}$Ni in the energy range E${}_{\gamma max}$ = 35...94 MeV

   O.S. Deiev🇺🇦 · I.S. Timchenko🇺🇦 · S.M. Olejnik🇺🇦 · S.M. Potin🇺🇦 · V.A. Kushnir🇺🇦 · V.V. Mytrochenko🇺🇦 · S.A. Perezhogin🇺🇦 · V.A. Bocharov🇺🇦

   The total bremsstrahlung flux-averaged cross-sections <$\sigma$(E${}_{\gamma max}$)> for the photonuclear reactions ${}^{nat}$Ni($\gamma$,xn)${}^{57}$Ni and ${}^{nat}$Ni($\gamma$,xn)${}^{56}$Ni have been measured in the range of end-point energies E${}_{\gamma max}$ = 35...94 MeV. The experiments were performed with the beam from the NSC KIPT electron linear accelerator LUE-40 with the use of the activation and off-line $\gamma$-ray spectrometric technique. The calculation of the flux-average cross-sections <$\sigma$(E${}_{\gamma max}$)>${}_{th}$ was carried out using the partial cross-section values $\sigma$(E) computed with the TALYS1.95 code and bremsstrahlung $\gamma$-flux calculated by GEANT4.9.2. The experimental results are compared with theoretical calculations and data from the literature. The obtained <$\sigma$(E${}_{\gamma max}$)> values expand the energy range of previously known experimental data.

   nucl-exNPA(2022)·7 citations
2. 02*

   Spontaneous fission of 246Fm

   A.V. Isaev🇷🇺 · R.S. Mukhin🇷🇺 · A.V. Andreev🇷🇺 · M.A. Bychkov🇷🇺 · M.L. Chelnokov🇷🇺 · V.I. Chepigin🇷🇺 · H.M. Devaraja🇷🇺 · O. Dorvaux🇫🇷 · M. Forge🇫🇷 · B. Gall🇫🇷 · K. Hauschild🇫🇷 · I.N. Izosimov🇷🇺 and 16 other authors

   An experiment on the study of the ${}^{246}$Fm spontaneous fission was conducted using the SHELS separator. The isotope was synthesized in the complete fusion reaction of ${}^{40}$Ar beam ions and ${}^{208}$Pb target nuclei. The neutron yields of ${}^{246}$Fm spontaneous fission ($\overline{\nu }=3.79\pm 0.30$, ${\sigma }_{\nu }^2=2.1$) were obtained using the SFiNx detector system. The multiplicity distribution of emitted prompt neutrons was restored using the Tikhonov method of statistical regularisation (${\overline{\nu }}_r=3.79\pm 0.20$, ${\sigma }_{\nu r}^2=2.8$). The spontaneous fission branching ratio ($b_{SF}=0.061\pm 0.005$) and the half-life ($T_{1/2}=1.50_{-0.07}^{+0.08}$ s) of the isotope were determined. The experimental data were compared with scission point model predictions. Excellent convergence was observed in the average number of neutrons per spontaneous fission process. However, the forms of the experimental and model prompt neutron multiplicity distributions differ significantly.

   nucl-exEPJA(2022)·13 citations
3. 03*

   Accurate Determination of the Electron Spin Polarization In Magnetized Iron and Nickel Foils for Møller Polarimetry

   D. C. Jones🇺🇸 · J. Napolitano🇺🇸 · P. A. Souder🇺🇸 · D. E. King🇺🇸 · W. Henry🇺🇸 · D. Gaskell🇺🇸 · K. Paschke🇺🇸

   The Møller polarimeter in Hall A at Jefferson Lab in Newport News, VA, has provided reliable measurements of electron beam polarization for the past two decades reaching the typically required $\pm$1\% level of absolute uncertainty. However, the upcoming proposed experimental program including MOLLER and SoLID have stringent requirements on beam polarimetry precision at the level of 0.4\% \cite{MOLLER2014, SoLID2019}, requiring a systematic re-examination of all the contributing uncertainties. Møller polarimetry uses the double polarized scattering asymmetry of a polarized electron beam on a target with polarized atomic electrons. The target is a ferromagnetic material magnetized to align the spins in a given direction. In Hall A, the target is a pure iron foil aligned perpendicular to the beam and magnetized out of plane parallel or antiparallel to the beam direction. The acceptance of the detector is engineered to collect scattered electrons close to 90${}^{\circ }$ in the center of mass frame where the analyzing power is a maximum (-7/9). One of the leading systematic errors comes from determination of the target foil polarization. Polarization of a magnetically saturated target foil requires knowledge of both the saturation magnetization and $g^{\prime }$, the electron $g$-factor which includes components from both spin and orbital angular momentum from which the spin fraction of magnetization is determined. This paper utilizes the existing world data to provide a best estimate for target polarization for both nickel and iron foils including uncertainties in magnetization, high-field and temperature dependence, and fractional contribution to magnetization from orbital effects. We determine the foil electron spin polarization at 294~K to be 0.08020$\pm$0.00018 (@4~T applied field) for iron and 0.018845$\pm 0.000053$ (@2~T applied field) for nickel.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2022)·7 citations
4. 04*

   The medium-modified $g\to c\bar{c}$ splitting function in the BDMPS-Z formalism

   Maximilian Attems🇨🇭 · Jasmine Brewer🇨🇭 · Gian Michele Innocenti🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Sohyun Park🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

   The formalism of Baier-Dokshitzer-Mueller-Peigné-Schiff and Zakharov determines the modifications of parton splittings in the QCD plasma that arise from medium-induced gluon radiation. Here, we study medium-modifications of the gluon splitting into a quark--anti-quark pair in this BDMPS-Z formalism. We derive a compact path-integral formulation that resums effects from an arbitrary number of interactions with the medium to leading order in the $1/N_c^2$ expansion. Analyses in the $N=1$ opacity and the saddle point approximations reveal two phenomena: a medium-induced momentum broadening of the relative quark--anti-quark pair momentum that increases the invariant mass of quark--anti-quark pairs, and a medium-enhanced production of such pairs. We note that both effects are numerically sizeable if the average momentum transfer from the medium is comparable to the quark mass. In ultra-relativistic heavy-ion collisions, this condition is satisfied for charm quarks. We therefore focus our numerical analysis on the medium modification of $g\to c\bar{c}$, although our derivation applies equally well to $g\to b\bar{b}$ and to gluons splitting into light-flavoured quark--anti-quark pairs.

   ↳ hep-phhep-thnucl-exnucl-thJHEP(2023)·36 citations
5. 05*

   Bubble Chamber Detectors with Light Nuclear Targets: A Snowmass 2021 White Paper

   Luis Alvarez-Ruso🇪🇸 · Joshua L. Barrow🇺🇸 · Leo Bellantoni🇺🇸 · Minerba Betancourt🇺🇸 · Alan Bross🇺🇸 · Linda Cremonesi🇬🇧 · Eric Dahl🇺🇸 · Kirsty Duffy🇬🇧 · Steven Dytman🇺🇸 · Laura Fields🇺🇸 · Tsutomu Fukuda🇯🇵 · Mikhail Gorchtein🇩🇪 and 20 other authors

   Neutrino cross sections are a critical ingredient in experiments that depend on neutrino scattering to reconstruct event kinematics and infer neutrino characteristics, like NOvA and T2K. An opportunity exists to reduce the 5-10% broad uncertainty on neutrino cross sections by producing more measurements of neutrino scattering from light nuclear targets at the relevant energies. Bubble chambers with light nuclear targets would be ideal for these measurements but the most recent device designed for use with an accelerator neutrino source is at least fifty years old. A new bubble chamber with light nuclear targets could be designed by observing how the technology has progressed for use in dark matter experiments and producing smaller modular devices that use more efficient cooling systems. A smaller modular device could also be designed for deployment to all functioning neutrino beams, but an investigation of the proper operating characteristics is necessary to adapt newer detectors to the structure of contemporary neutrino beams.

   ↳ physics.ins-dethep-exnucl-ex6 citations
6. 06*

   Can Transverse Mass Scaling Shed Light on the Event-Activity Dependence of ${\rm Y}$ Mesons Production at LHC?

   Iakov Aizenberg (1)🇮🇱 · Zvi Citron (2)🇮🇱 · Alexander Milov (1) ((1) Department of Physics and Astrophysics, Weizmann Institute of Science, Rehovot, Israel (2) Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel)🇮🇱

   Measurements by the CMS experiment [CMS Collaboration, JHEP04 (2014) 103; CMS Collaboration, JHEP11 (2020) 001] reveal a deficit of charged particle tracks in events with higher ${\rm Y}$(nS) states. This observation is suggested to be a manifestation of the excited bottomonia suppression in $pp$ interactions. Transverse mass ($m_{\mathrm{T}}$) scaling can be implied to check this assumption in an independent way. The scaling has been observed for a wide range of particle species in proton-proton collisions at various energies from the SPS to RHIC and the LHC. The observed scaling is known to be different for baryons and mesons, and this work presents a comprehensive study of the $m_{\mathrm{T}}$-scaling of mesons at LHC energies with a focus on heavier mesons. The study demonstrates patterns in the scaling properties of mesons, which are related to the particle quark content. In particular, light species and ground-state quarkonia obey the same scaling, whereas open-flavor particles deviate from it because their spectra are significantly harder. The magnitude of deviation depends on the flavor of the heaviest quark in the meson. By extending the $m_{\mathrm{T}}$-scaling assumption to the excited bottomonia states, it is observed that the measured cross sections of ${\rm Y}$(2S) and ${\rm Y}$(3S) are reduced by factors of 1.6 and 2.4 compared to the expectation from the scaling. This observation is consistent with recently observed differences between the event-activity dependence of different ${\rm Y}$(nS) meson states.

   ↳ hep-phnucl-exPRD(2023)·3 citations
7. 07*

   $R$-matrix analysis of ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg and ${}^{22}$Ne($\alpha$, $\gamma$)${}^{26}$Mg reaction

   Rajkumar Santra🇮🇳

   The ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg and its competing channel ${}^{22}$Ne($\alpha$, $\gamma$)${}^{26}$Mg has an major influence on neutron flux in weak s-process nucleosynthesis path in low mass AGB stars and massive stars of mass (M$\ge$ 10M${}_{\odot }$). So the ratio rate of this two competing reaction control the neutron flux in weak s-process nucleosynthesis. Various experiment has been performed to study the properties of nuclear states of ${}^{26}$Mg to evaluate rate of ${}^{22}$Ne+$\alpha$ reaction rate and corresponding rate from these studies vary by up to a factor of 500 in the astrophysical relevant temperature. The recent evaluation by Philip et al. of ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg reaction rate using most recent nuclear data of ${}^{26}$Mg from number of sources shows similar result with previous estimation for ${}^{22}$Ne($\alpha$, $\gamma$)${}^{26}$Mg but got lower rate for ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg reaction due to updated nuclear data. Also Philip et al. suggested that rate based on full $R$-matrix modeling will required to take into accounted the interference effects between distant levels and sub-threshold resonance. In present work full $R$-matrix calculation has been performed for ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg and ${}^{22}$Ne($\alpha$, $\gamma$)${}^{26}$Mg reaction based on fitting the ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg reaction data of Jaeger et al; in energy range 0.8 to 1.45 MeV and updated nuclear data of ${}^{26}$Mg states. The $R$-matrix fitting for the ${}^{22}$Ne($\alpha$, n)${}^{25}$Mg reaction nicely explain experimental data in 0.8 to 1.45 MeV energy range by changing spin, parity of E${}_x$ = 11.784 and 11.63 MeV states from 1${}^{-}$ to 0${}^{+}$.

   ↳ nucl-thnucl-ex0 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.