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Hague, T. J.

Publications and source records attributed to Hague, T. J..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Impact of the MARATHON data on F 2⁢n⁡ /F 2⁢p and off-shell effects in light nuclei

The neutron structure function, F 2⁢n⁡ , has historically been extracted from measurements of the deuteron structure function, which is limited by our understanding of the nuclear effects on the bound proton and neutron. The MARATHON Collaboration recently extracted F 2⁢n⁡ from the comparison of 3 H and 3 He targets, where the nuclear effects are larger but nearly identical, yielding a precise extraction of F 2⁢n⁡ /F 2⁢p . Here, to ensure that this comparison is not biased by the specific model of nuclear effects used by MARATHON, we examine a range of models of the nuclear effects to obtain a more conservative, but more model-independent, extraction of F 2⁢n⁡ /F 2⁢p for comparison with deuteron extractions. Even with this approach, the results are precise enough to compare to deuteron extractions, providing new constraints on the nuclear effects in the deuteron and indicating the need for larger nuclear corrections than those included in most models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Electroproduction of the Λ/Σ 0 hyperons at Q 2 ≃ 0.5 (GeV/c) 2 at forward angles

In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an nn⁢Λ state in the reconstructed missing mass distribution from a tritium gas target [K. N. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 013D01 (2022); B. Pandey et al., Phys. Rev. C 105, L051001 (2022)]. As part of this investigation, data were also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of Λ/Σ 0 electroproduction. This dataset was acquired at Q 2 ≃ 0.5 (GeV/c) 2 , W = 2.14 GeV, and θ$^{c.m.}_{γK}$ ≃ 8°. It covers forward angles where photoproduction data are scarce and a low-Q 2 region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher Q 2 than previous hypernuclear experiments, thus providing crucial information for understanding the Q 2 dependence of the differential cross sections for Λ/Σ 0 hyperon electroproduction. Here, this paper reports on the Q 2 dependence of the differential cross section for the e + p → e' + K + + Λ/Σ 0 reaction at 0.2–0.8 (GeV/c) 2 , and provides comparisons with the currently available theoretical models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Search for axion-like particles through nuclear Primakoff production using the GlueX detector

We report on the results of the first search for the production of axion-like particles (ALPs) via Primakoff production on nuclear targets, γA → aA, in the “SRC-CT” experiment using the GlueX detector at Jefferson Lab. This search uses an integrated luminosity of 100 pb -1 nucleon on a 12 C target with a real photon beam of energies 6 < E γ < 10.8 GeV, and explores the mass region of 200 < m a < 450 MeV via the decay a → γγ. This mass range is between the π 0 and η meson masses, which enables the use of the measured η meson production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the effective photon coupling scale of $\mathscr{O}$(1 TeV -1 ). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background the in GlueX spectrometer, which we treat by using data on 4 He to estimate and subtract it. We comment on how this search can be improved in a future higher-statistics dedicated measurement.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Novel Measurement of the Neutron Magnetic Form Factor from A=3 Mirror Nuclei

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei 3 H and 3 He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6 < Q 2 < 2.9 GeV 2 , where existing measurements give inconsistent results. The precision and Q 2 range of these data allow for a better understanding of the current world’s data and suggest a path toward further improvement of our overall understanding of the neutron’s magnetic form factor.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Estimation of combinatoric background in seaquest using an event-mixing method

All experiments observing dilepton pairs (e.g. e + e -, μ + μ - ) must confront the existence of a combinatoricbackground caused by the combining of tracks not arising from the same physics vertex. Some method must be devised to calculate and remove this background. In this document we describe a particular event-mixing method relying on many of the unique aspects of the SeaQuest spectrometer and data. The method described here calculates the combinatoric background with correct normalization; i.e., there is no need to assign a floating normalization factor that is then determined in a subsequent fitting procedure. Numerous tests are applied to demonstrate the reliability of the method.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of the J/ψ photoproduction cross section over the full near-threshold kinematic region

Here, we report the total and differential cross sections for $J/\psi$ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold at 8.2 GeV up to 11.44 GeV and over the full kinematic range of momentum transfer squared, $t$. Such coverage facilitates the extrapolation of the differential cross sections to the forward ($t = 0$) point beyond the physical region. The forward cross section is used by many theoretical models and plays an important role in understanding $J/\psi$ photoproduction and its relation to the $J/\psi$-proton interaction. These measurements of $J/\psi$ photoproduction near threshold are also crucial inputs to theoretical models that are used to study important aspects of the gluon structure of the proton, such as the gluon Generalized Parton Distribution (GPD) of the proton, the mass radius of the proton, and the trace anomaly contribution to the proton mass. We observe possible structures in the total cross section energy dependence and find evidence for contributions beyond gluon exchange in the differential cross section close to threshold, both of which are consistent with contributions from open-charm intermediate states.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Determination of the titanium spectral function from ($e,e'p$) data

The E12-14-012 experiment, performed in Jefferson Lab Hall A, has measured the (e, e'p) cross section in parallel kinematics using a natural titanium target. In this paper, we report the analysis of the dataset obtained in different kinematics for our solid natural titanium target. Data were obtained in a range of missing momentum and missing energy between 15 ≲ p m ≲ 250 MeV / c and 12 ≲ E m ≲ 80 MeV, respectively, and using an electron beam energy of 2.2 GeV. We measured the reduced cross section with ~7% accuracy as a function of both missing momentum and missing energy. Furthermore, our Monte Carlo simulation, including both a model spectral function and the effects of final-state interactions, satisfactorily reproduces the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗