Proton propagation in nuclei studied in the (e,e’p) reaction

Proton propagation in nuclei was studied using the (e,e’p) reaction in the quasifree region. The coincidence (e,e’p) cross sections were measured at an electron angle of 50.4° and proton angles of 50.1°, 58.2°, 67.9°, and 72.9° for 12C, 27Al, 58Ni, and 181Ta targets at a beam energy of 779.5 MeV. The average outgoing proton energy was 180 MeV. The ratio of the (e,e’p) yield to the simultaneously measured (e,e’) yield was compared to that calculated in the plane-wave impulse approximation and an experimental transmission defined. These experimental transmissions are considerably larger (a factor of ∼2 for 181Ta) than those one would calculate from the free N-N cross sections folded into the nuclear density distribution. A new calculation that includes medium effects (N-N correlations, density dependence of the N-N cross sections and Pauli suppression) accounts for this increase

Magnetic measurement of quadrupole and sextupole magnets for the MIT-Bates South Hall Ring (SHR)

Final results of magnetic measurements of 128 quadrupoles and 32 sextupoles are presented. There are many places in the SHR complex where these magnets will be operated from a common power supply. For the quadrupole magnets there are 4 octets, 4 triplets and 18 doublets; these magnets have been matched to [plus minus]0.1% in excitation response for the operating range corresponding to 0.3--1.0 GeV. For the sextupoles there are four octets where the (pairwise) matching has generally been made to the [plus minus]0.3% level. Parameterization of the data as well as fits are described and examples of the magnet groupings are shown

A test of high-energy electron bremsstrahlung calculations

The dependence on atomic number Z of commonly used formulae for calculating electron bremsstrahlung spectra is tested by making measurements of d(γ,p)n cross-sections using aluminum and tungsten radiators for 165 MeV incident electrons. The ratio of the photon yield produced in the tungsten radiator to that produced in the aluminum radiator is determined, with an overall experimental uncertainty of about 10% per 5 MeV, as a function of photon energy in the range 70 less than or equal E<sub>γ</sub> less than or equal 150 MeV, and compared with the ratio obtained from theory. Good agreement with theory is found for photon energies between 90 and 120 MeV. Outside this range, the theoretical ratio underestimates the measurement by about 5% for lower and 15% for higher photon energies

Experimental test of virtual photon theory via electrodisintegration and photodisintegration of the deuteron

Virtual photon theory (VPT) has long been suggested as a means of extracting photoreaction cross sections from measurements of cross sections for equivalent electron-induced reactions. Experimental information on the validity of VPT is, however, extremely limited. A test of VPT is reported in this paper. Measurements of the cross section for the d(e,p)e' n reaction at energies between 165 and 365 MeV have been performed for outgoing proton angles of 40degrees, 90degrees, and 120degrees. From these results, cross sections for the d(gamma,p)n reaction have been extracted using VPT, and are compared with d(gamma,p)n cross sections measured concurrently using a bremsstrahlung beam

Proton propagation in nuclei studied in the A dependence of the (e,e’p) reaction in the quasifree region

The A dependence of the (e,e’p) reaction in the quasifree region has been measured at an average Q2 of 0.33 (GeV/c)2 for targets of 12C, 27Al, 58Ni, and 181Ta. The outgoing proton kinetic energy was 180±30 MeV. By comparing the ratio of (e,e’p) coincidence to (e,e’) singles yields, average proton transmissions are obtained for each target. The resulting ‘‘mean free path’’ or, more precisely, the attenuation length for protons in the nucleus is significantly longer than expectations based on the free nucleon-nucleon cross section