Publications by authors named "J C McGeorge"
The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage.
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- The study discusses how the size and shape of the neutron skin in lead-208 ((208)Pb) were analyzed using pion photoproduction cross sections measured by the Crystal Ball detector at the MAMI facility.
- The neutron distribution was characterized with specific measurements: a half-height radius of 6.70 ± 0.03 fm and a diffuseness of 0.55 ± 0.01(stat) (-0.03)(+0.02)(sys) fm, leading to a neutron skin thickness of 0.15 ± 0.03(stat) (-0.03)(+0.01)(sys) fm.
- This is the first time neutron skin thickness has been effectively measured using an electromagnetic approach, revealing that
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- Precise angular distributions for π0 meson photoproduction off neutrons in deuterons were measured for the first time, eliminating effects from nuclear Fermi motion through complete kinematic reconstruction.
- Final-state interaction effects were assessed by comparing reaction cross sections for quasifree protons in deuterons to those of free protons, applied as a correction to the quasifree neutron findings.
- Results from the experiment at the Mainz Microtron MAMI revealed significant discrepancies in model predictions, providing important constraints for future analyses, particularly within the Bonn-Gatchina coupled-channel framework.
We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.
View Article and Find Full Text PDFThe photoproduction of η mesons off nucleons bound in 2H and 3He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility.
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