1. |
- Dutta, D, et al.
(author)
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Nuclear transparency with the gamma n ->pi(-)p process in He-4
- 2003
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 68:2: 021001
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Journal article (peer-reviewed)abstract
- We have measured the nuclear transparency of the fundamental process gamman-->pi(-)p in He-4. These measurements were performed at Jefferson Lab in the photon energy range of 1.6-4.5 GeV and at theta(cm)(pi)=70degrees and 90degrees. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.
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2. |
- Schulte, EC, et al.
(author)
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High energy angular distribution measurements of the exclusive deuteron photodisintegration reaction
- 2002
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In: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:4
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Journal article (peer-reviewed)abstract
- The first complete measurements of the angular distributions of the two-body deuteron photodisintegration differential cross section at photon energies above 1.6 GeV were performed at the Thomas Jefferson National Accelerator Facility. The results show a persistent forward-backward asymmetry up to E-gamma=2.4 GeV, the highest-energy measured in this experiment. The Hard Rescattering and the Quark-Gluon string models are in fair agreement with the results.
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3. |
- Wijesooriya, K, et al.
(author)
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Polarization measurements in neutral pion photoproduction
- 2002
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:3
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Journal article (peer-reviewed)abstract
- We present measurements of the recoil proton polarization for the H-1((γ) over right arrow,(p) over right arrow)pi(0) reaction for theta(c.m.)(pi) = 60degrees-135degrees and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region.
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4. |
- Zhu, LY, et al.
(author)
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Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium
- 2003
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In: Physical Review Letters. - 1079-7114. ; 91:2: 022003
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Journal article (peer-reviewed)abstract
- We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma)greater than or similar to3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.
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