The ratio of the proton's elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub ... more The ratio of the proton's elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub p}} was obtained by measuring P{sub i} and P{sub l}, the transverse and the longitudinal recoil proton polarization, respectively. For elastic ep to ep, G{sub E{sub p}}/G{sub M{sub p}} is ...
We report the measurement of beam-target double spin asymmetries (A LT ) in the inclusive product... more We report the measurement of beam-target double spin asymmetries (A LT ) in the inclusive production of identified hadrons, e + 3 He ↑ → h + X, using a longitudinally polarized 5.9-GeV electron beam and a transversely polarized 3 He target. Hadrons (π ± , K ± , and proton) were detected at 16 • with an average momentum P h = 2.35 GeV/c and a transverse momentum (p T ) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the 3 He target were observed to be nonzero for π ± production when the target was polarized transversely in the horizontal plane. The π + and π − asymmetries have opposite signs, analogous to the behavior of A LT in semi-inclusive deep-inelastic scattering.
The 1 H(e, e ′ π + )n cross section was measured at four-momentum transfers of Q 2 =1.60 and 2.45... more The 1 H(e, e ′ π + )n cross section was measured at four-momentum transfers of Q 2 =1.60 and 2.45 GeV 2 at an invariant mass of the photon nucleon system of W =2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q 2 by one sigma, but is still far from its perturbative Quantum Chromo-Dynamics prediction.
An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferso... more An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferson Lab on a 12 C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed 12 Λ B spectrum shows for the first time
We report the first measurement of the double-spin asymmetry ALT for charged pion electroproducti... more We report the first measurement of the double-spin asymmetry ALT for charged pion electroproduction in semi-inclusive deep inelastic electron scattering on a transversely polarized 3 He target. The kinematics focused on the valence quark region, 0.16 < x < 0.35 with 1.4 < Q 2 < 2.7 GeV 2 . The corresponding neutron ALT asymmetries were extracted from the measured 3 He asymmetries and proton/ 3 He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g q 1T and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for π - production on 3 He and the neutron, while our π + asymmetries are consistent with zero.
Exclusive electroproduction of π 0 mesons on protons in the backward hemisphere has been studied ... more Exclusive electroproduction of π 0 mesons on protons in the backward hemisphere has been studied at Q 2 = 1.0 GeV 2 by detecting protons in the forward direction in coincidence with scattered electrons from the 4 GeV electron beam in Jefferson Lab's Hall A. The data span the range of the total (γ * p) center-of-mass energy W from the pion production threshold to W = 2.0 GeV. The differential cross sections σT + ǫ σL, σTL, and σTT were separated from the azimuthal distribution and are presented together with the MAID [1, 2, 3] and SAID parametrizations.
The ratio of the proton's elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub ... more The ratio of the proton's elastic electromagnetic form factors, G{sub E{sub p}}/G{sub M{sub p}} was obtained by measuring P{sub i} and P{sub l}, the transverse and the longitudinal recoil proton polarization, respectively. For elastic ep to ep, G{sub E{sub p}}/G{sub M{sub p}} is ...
We report the measurement of beam-target double spin asymmetries (A LT ) in the inclusive product... more We report the measurement of beam-target double spin asymmetries (A LT ) in the inclusive production of identified hadrons, e + 3 He ↑ → h + X, using a longitudinally polarized 5.9-GeV electron beam and a transversely polarized 3 He target. Hadrons (π ± , K ± , and proton) were detected at 16 • with an average momentum P h = 2.35 GeV/c and a transverse momentum (p T ) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the 3 He target were observed to be nonzero for π ± production when the target was polarized transversely in the horizontal plane. The π + and π − asymmetries have opposite signs, analogous to the behavior of A LT in semi-inclusive deep-inelastic scattering.
The 1 H(e, e ′ π + )n cross section was measured at four-momentum transfers of Q 2 =1.60 and 2.45... more The 1 H(e, e ′ π + )n cross section was measured at four-momentum transfers of Q 2 =1.60 and 2.45 GeV 2 at an invariant mass of the photon nucleon system of W =2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q 2 by one sigma, but is still far from its perturbative Quantum Chromo-Dynamics prediction.
An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferso... more An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferson Lab on a 12 C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed 12 Λ B spectrum shows for the first time
We report the first measurement of the double-spin asymmetry ALT for charged pion electroproducti... more We report the first measurement of the double-spin asymmetry ALT for charged pion electroproduction in semi-inclusive deep inelastic electron scattering on a transversely polarized 3 He target. The kinematics focused on the valence quark region, 0.16 < x < 0.35 with 1.4 < Q 2 < 2.7 GeV 2 . The corresponding neutron ALT asymmetries were extracted from the measured 3 He asymmetries and proton/ 3 He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g q 1T and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for π - production on 3 He and the neutron, while our π + asymmetries are consistent with zero.
Exclusive electroproduction of π 0 mesons on protons in the backward hemisphere has been studied ... more Exclusive electroproduction of π 0 mesons on protons in the backward hemisphere has been studied at Q 2 = 1.0 GeV 2 by detecting protons in the forward direction in coincidence with scattered electrons from the 4 GeV electron beam in Jefferson Lab's Hall A. The data span the range of the total (γ * p) center-of-mass energy W from the pion production threshold to W = 2.0 GeV. The differential cross sections σT + ǫ σL, σTL, and σTT were separated from the azimuthal distribution and are presented together with the MAID [1, 2, 3] and SAID parametrizations.
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Papers by K. Aniol