A study of the (\u272)H(p,2p)n reaction at intermediate energy

Exclusive cross sections for the (\u272)H(p,2p)n reaction at beam energies of 507 and 508 MeV have been measured at various kinematics. The results are compared with the predictions of the impulse approximation and of a calculation of the 6 lowest order terms of a multiple scattering expansion of the (tau)-matrix. at small internal momenta larger than 200 MeV/c a drastic deviation from theory is confirmed. Possible causes for these results are discussed

The Proton Form Factor Ratio Measurements at Jefferson Lab

The ratio of the proton form factors, GEp/GMp, has been measured from Q(2) of 0.5 GeV2 to 8.5 GeV2, at the Jefferson Laboratory, using the polarization transfer method. This ratio is extracted directly from the measured ratio of the transverse and longitudinal polarization components of the recoiling proton in elastic electron-proton scattering. The discovery that the proton form factor ratio measured in these experiments decreases approximately linearly with four-momentum transfer, Q(2), for values above approximate to 1 GeV2, is one of the most significant results to come out of JLab. These results have had a large impact on progress in hadronic physics; and have required a significant rethinking of nucleon structure. There is an approved experiment at JLab, GEp(5), to continue the ratio measurements to 12 GeV2. A dedicated experimental setup, the Super Bigbite Spectrometer (SBS), will be built for this purpose. In this paper, the present status of the proton elastic electromagnetic form factors and a number of theoretical approaches to describe nucleon form factors will be discussed

Final Report for Grant DE-FG02-03ER41253

This is the final report of activity under this grant. The polarimeter is built and awaits installation in the HMS in Hall C, now planned for the Spring of 2007. The experiment itself will occur in the second half of 2007. The parameters of the drift chambers have been studied experimentally and found to satisfy our original request

Measurements of the electromagnetic form factor of the Proton at JLab

The ratio of the proton’s elastic electromagnetic form factors GEp/GMp was obtained by measuring Pt and Pℓ, the transverse and longitudinal recoil proton polarization, respectively. For the elastic reaction ⃗ep→e⃗p, GEp/GMp is proportional to Pt/Pℓ. The simultaneous measurement of Pt and Pℓ in a polarimeter reduces systematic uncertainties. The results for the ratio GEp/GMp measured in Hall A so far show a systematic decrease with increasing Q 2, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. Together these experiments cover the Q 2- range of 0.5 to 5.6 GeV 2. A new experiment is currently being prepared, to extend the Q 2-range to 9 GeV 2 in Hall C.

Survey of nucleon electromagnetic form factors

There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double polarization experiments, in compar- ison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at MIT-Bates, MAMI, and JLab. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed

Measurement of G

The ratio of the electric and magnetic form factors of the proton, G{sub E{sub p}}/G{sub M{sub p}}, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic {rvec e}p {yields} e{rvec p} reaction. The new data presented in this article span the range 3.5 < Q{sup 2} < 5.6 GeV{sup 2} and are well described by a linear Q{sup 2} fit. Also, the ratio QF{sub 2p}/F{sub 1p} reaches a constant value above Q{sup 2}=2 GeV{sup 2}

Measurement of analysing powers for neutron scattering on CH2, CH, C and Cu target for momenta from 3.0 to 4.2 GeV/c

During two beam runs in the years 2016 and 2017, the analyzing powers (Ay) for protons and neutrons scattering on CH2, CH, C and Cu targets were measured at the nucleon momentum from 3.0 to 4.2 GeV/c with the ALPOM2 setup at the Nuclotron accelerator. The data for polarized neutron beam are obtained for the first time, thanks to the unique polarized deuteron beam that is presently available up to 13 GeV/c. Earlier, analyzing powers for polarized neutrons had been measured only for thin hydrogen targets. Cross sections and analyzing powers for np, for both elastic scattering and charge exchange are known up to 29 GeV/c. No data existed for thick analyzers. The measurement of the angular dependence of Ay for the neutron is essential to the continuation of the neutron form factor measurements to the highest possible transferred momentum-Q2 at the Jefferson Laboratory. The reaction p+Cu(W), with the detection of a neutron in the forward direction by a hadron calorimeter, can be used for the measurement of the proton polarization at the future NICA collider

Polarization Transfer in the He-4(polarized-e, e-prime polarized-p)H-3 Reaction up to Q{sup 2}=2.6 (GeV/c){sup 2}

We have measured the proton recoil polarization in the {sup 4}He(polarized-e, e-prime, p){sup 3}H reaction at Q{sup 2} = 0.5, 1.0, 1.6, and 2.6 (GeV/c){sup 2}. The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a predicted medium modification of the proton form factors based on a quark-meson coupling model. In contrast, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control