Fri·Dec 2, 2022Friday·December 2, 2022

1. 01*

   Secondary Neutron Production from Thick Target Deuteron Breakup

   Jonathan T. Morrell🇺🇸 · Andrew S. Voyles🇺🇸 · Jon C. Batchelder🇺🇸 · Joshua A. Brown · Lee A. Bernstein

   Thick target deuteron breakup is a variable-energy accelerator-based source of high-energy neutrons, with applications in fundamental and applied nuclear science and engineering. However, the breakup mechanism remains poorly understood, and data on neutron yields from thick target breakup remains relatively scarce. In this work, the double-differential neutron yields from deuteron breakup have been measured on a thick beryllium target at ${ϵ}_d=33$ and 40 MeV, using both time-of-flight and activation techniques. We have also introduced a simple hybrid model for the double-differential deuteron breakup cross section, applicable in the ${ϵ}_d=10$--$100$ MeV energy range on light ($Z\le 6$) targets. This model features four empirical parameters that have been fit to reproduce experimental breakup measurements on beryllium targets, using the method of least-squares. It was shown that these parameters extrapolate well to higher energies, and to other low-Z target materials. We also include optimization of the parameters that modify the Kalbach systematics for compound and pre-equilibrium reactions, in order to better reproduce the experimental data for beryllium targets at large angles.

   nucl-exnucl-thphysics.med-phPRC(2023)·3 citations
2. 02*

   Isoscalar giant monopole strength in ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb

   A. Bahini (1 and 2)🇿🇦 · R. Neveling (2)🇿🇦 · P. von Neumann-Cosel (3)🇩🇪 · J. Carter (1)🇿🇦 · I. T. Usman (1)🇿🇦 · P. Adsley (1, 2, 4, and 5)🇿🇦 · N. Botha (1)🇿🇦 · J. W. Brümmer (2 and 4)🇿🇦 · L. M. Donaldson (2)🇿🇦 · S. Jongile (2 and 4)🇿🇦 · T. C. Khumalo (1, 2, and 6)🇿🇦 · M. B. Latif (1 and 2)🇿🇦 and 13 other authors

   Inelastic $\alpha$-particle scattering at energies of a few hundred MeV and very-forward scattering angles including $0^{\circ }$ has been established as a tool for the study of the isoscalar giant monopole (IS0) strength distributions in nuclei. An independent investigation of the IS0 strength in nuclei across a wide mass range was performed using the $0^{\circ }$ facility at iThemba Laboratory for Accelerator Based Sciences (iThemba LABS), South Africa, to understand differences observed between IS0 strength distributions in previous experiments performed at the Texas A\&M University (TAMU) Cyclotron Institute, USA and the Research Center for Nuclear Physics (RCNP), Japan. The isoscalar giant monopole resonance (ISGMR) was excited in ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb using $\alpha$-particle inelastic scattering with $196$ MeV $\alpha$ beam and scattering angles ${\theta }_{\text{Lab}}=0^{\circ }$ and $4^{\circ }$. The K$600$ magnetic spectrometer at iThemba LABS was used to detect and momentum analyze the inelastically scattered $\alpha$ particles. The IS0 strength distributions in the nuclei studied were deduced with the difference-of-spectra (DoS) technique including a correction factor for the $4^{\circ }$ data based on the decomposition of $L>0$ cross sections in previous experiments. IS0 strength distributions for ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb are extracted in the excitation-energy region $E_{\mathrm{x}}=9-25$ MeV.Using correction factors extracted from the RCNP experiments, there is a fair agreement with their published IS0 results. Good agreement for IS0 strength in ${}^{58}$Ni is also obtained with correction factors deduced from the TAMU results, while marked differences are found for ${}^{90}$Zr and ${}^{208}$Pb.

   nucl-exPRC(2023)·8 citations
3. 03*

   Hot and Cold QCD White Paper from ALICE-USA: Input for 2023 U.S. Long Range Plan for Nuclear Science

   N. Alizadehvandchali🇺🇸 · N. Apadula🇺🇸 · M. Arslandok🇺🇸 · C. Beattie🇺🇸 · R. Bellwied🇺🇸 · J. T. Blair🇺🇸 · F. Bock🇺🇸 · H. Bossi🇺🇸 · A. Bylinkin🇺🇸 · H. Caines🇺🇸 · I. Chakaberia🇺🇸 · M. Cherney🇺🇸 and 71 other authors

   The ALICE-USA collaboration presents its plans for the 2023 U.S. Long Range Plan for Nuclear Science.

   nucl-exhep-ex8 citations
4. 04*

   A Strong-QCD Regime Measurement of the Proton's Spin Structure

   David Ruth🇺🇸

   The theory of the strong force, Quantum Chromodynamics (QCD) remains one of the most important ways to understand the fundamental properties of ordinary matter. However, at low momentum transfer Q2, in the regime where the strong force becomes extremely strong, our understanding of QCD for ordinary nucleons becomes hazy. Several cutting edge theories such as Chiral Perturbation Theory and Lattice QCD have provided valuable predictions in this regime, but Lattice QCD has not yet extended predictions of many important quantities to this kinematic region, and Chiral Perturbation Theory has faced several important disagreements with experimental data for the neutron over the last several decades. It is therefore of extreme importance to have a benchmark of experimental data in the low energy regime for the proton's behavior, as a test of leading theories for the behavior of QCD in this regime. The E08-027 (g2p) experiment ran at Jefferson Lab in 2012 with the goal of collecting this valuable data. Full details of the g2p experiment and my experimental work at the University of New Hampshire are presented in this thesis, as well as a detailed description of the analysis process and the exciting benchmark results, which serve as a direct test of all current and future theories of QCD in the low-Q2 regime.

   nucl-exnucl-thphysics.acc-phphysics.atom-ph0 citations
5. 05*

   Ab initio investigations of A=8 nuclei: $\alpha -\alpha$ scattering, deformation in ${}^8$He, radiative capture of protons on ${}^7$Be and ${}^7$Li and the X17 boson

   P. Navratil🇨🇦 · K. Kravvaris🇺🇸 · P. Gysbers🇨🇦 · C. Hebborn🇺🇸 · G. Hupin🇫🇷 · S. Quaglioni🇺🇸

   We apply the No-Core Shell Model with Continuum (NCSMC) that is capable of describing both bound and unbound states in light nuclei in a unified way with chiral two- and three-nucleon interactions as the only input. The NCSMC can predict structure and dynamics of light nuclei and, by comparing to available experimental data, test the quality of chiral nuclear forces. We discuss applications of NCSMC to the $\alpha -\alpha$ scattering and the structure of ${}^8$Be, the p+${}^7$Be and p+${}^7$Li radiative capture and the production of the hypothetical X17 boson claimed in ATOMKI experiments. The ${}^7$Be(p,$\gamma$)${}^8$B reaction plays a role in Solar nucleosynthesis and Solar neutrino physics and has been subject of numerous experimental investigations. We also highlight our investigation of the neutron rich exotic ${}^8$He that has been recently studied experimentally at TRIUMF with an unexpected deformation reported.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2023)·1 citation
6. 06*

   Fusion systematics for weakly bound nuclei using neutron flow and collective degrees of freedom

   S. Appannababu · V. V. Parkar · V. Jha🇮🇳 · S. Kailas

   A systematic analysis of the fusion cross sections around the Coulomb barrier energies with stable weakly bound (${}^6$Li,${}^7$Li,${}^9$Be) and strongly bound ${}^{12}$C projectiles on various targets was performed by using neutron flow model and coupled channels approach. The analysis show that both the models are successful in explaining the near barrier fusion data. Further, it is also observed that the collective degrees of freedom as well as the neutron flow influence the near barrier fusion process involving weakly bound projectiles.

   ↳ nucl-thnucl-exPRC(2022)·3 citations
7. 07*

   Accessing chiral-even quark generalised parton distributions in the exclusive photoproduction of a $\gamma {\pi }^{\pm }$ pair with large invariant mass in both fixed-target and collider experiments

   Goran Duplančić🇭🇷 · Saad Nabeebaccus🇫🇷 · Kornelija Passek-Kumerički🇭🇷 · Bernard Pire🇫🇷 · Lech Szymanowski🇵🇱 · Samuel Wallon🇫🇷

   We compute the exclusive photoproduction of a $\gamma {\pi }^{\pm }$ pair using the collinear factorisation framework, in the kinematic regime where the pair has a large invariant mass. This exclusive channel presents a new avenue for the investigation of GPDs. It is particularly interesting as the high centre of mass energies available at future experiments will allow the study of GPDs at small skewness $\xi$. We compute the scattering amplitude of the process, at leading twist and leading order in ${\alpha }_s$, which is used to estimate its cross-section and linear polarisation asymmetries with respect to the incoming photon, for JLab~12-GeV, COMPASS, future EIC and LHC (in ultra-peripheral collisions) kinematics. We find that the order of magnitude of estimates are sufficiently large for a dedicated experimental analysis to be performed, especially at JLab. We also compare the results from an asymptotic distribution amplitude (DA) to those using a recently proposed \textit{holographic} DA.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2023)·46 citations
8. 08*

   Estimated performance of the TRIUMF ultracold neutron source and electric dipole moment apparatus

   Steve Sidhu🇨🇦 · Wolfgang Schreyer🇨🇦 · Sean Vanbergen🇨🇦 · Shinsuke Kawasaki🇯🇵 · Ryohei Matsumiya🇨🇦 · Takahiro Okamura🇨🇦 · Ruediger Picker🇨🇦

   Searches for the permanent electric dipole moment of the neutron (nEDM) provide strong constraints on theories beyond the Standard Model of particle physics. The TUCAN collaboration is constructing a source for ultracold neutrons (UCN) and an apparatus to search for the nEDM at TRIUMF, Vancouver, Canada. In this work, we estimate that the spallation-driven UCN source based on a superfluid helium converter will provide $(1.38\pm 0.02)\times 10^7$ polarized UCN at a density of $217\pm 3$~UCN/cm${}^3$ to a room-temperature EDM experiment per fill. With $(1.51\pm 0.02)\times 10^6$ neutrons detected after the Ramsey cycle, the statistical sensitivity for an nEDM search per storage cycle will be $(1.94\pm 0.06)\times 10^{-25}e$cm (1$\sigma$). The goal sensitivity of $10^{-27}e$cm (1$\sigma$) can be reached within $280\pm 16$ measurement days.

   ↳ physics.ins-detnucl-exEPJ Web Conf.(2023)·10 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.