In the course of a systematic investigation of proton-induced reactions for p energies between 800 and 2600 MeV, the target elements O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zr, Rh, Nb, Ba and ...Au were irradiated with 800 MeV protons at LAMPF/Los Alamos National Laboratory, and with 1200, 1600 and 2600 MeV protons at Laboratoire National Saturne/Saclay. The 1600 MeV irradiations covered in addition the target elements C, N, Rb, Sr, Y. The study was designed to measure production cross sections of radionuclides by γ-spectrometry and by accelerator mass spectrometry and of stable rare gas isotopes by conventional mass spectrometry. A detailed analysis of secondary particle fields was performed for targets of different thicknesses. Corrections for interferences by secondaries were made on the basis of secondary particle spectra as calculated by the code HET in the form of the HERMES code system and experimental and theoretical excitation functions of p- and n-induced reactions. Here, about 700 cross sections for the production of radionuclides from target elements
Z ≤ 29 (Cu) by more than 200 reactions are presented. In addition, cross sections for the production of stable He and Ne isotopes from iron at a proton energy of 600 MeV are given. Together with earlier work of our group, there now exists a consistent set of excitation functions from threshold energies up to 2600 MeV. A comparison of the new data with earlier measurements from other authors exhibited a considerable lack of reliability for many of the earlier data. On the basis of the new data, the quality of existing semiempirical formulas for the calculation of spallation cross sections is discussed. In a more physical approach, the production of residual nuclides is calculated in the framework of an INC/E model using Monte Carlo techniques for energies between 100 MeV and 5 GeV and compared with the experimental results.
High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several ...large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10/sup 8/ protons cm/sup -2/ (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures of T<or=110 degrees C while kept in their specially designed cryostats. The authors show that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.< >
New, high-precision measurements of the 3He(e,ep) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at ...energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-type calculations account for some of the observed excess cross-section, but significant differences remain.
New, high-precision measurements of the 3He(e,e(')p) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at ...energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-type calculations account for some of the observed excess cross-section, but significant differences remain.
New, high-precision measurements of the 3He(e,e'p) reaction using the A1 collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at ...energy transfers below the quasi-elastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on Plane Wave Impulse Approximation were observed in both the two- and three-body breakup channels. Full Faddeev-type calculations account for some of the observed excess cross section, but significant differences remain.
Single spin azimuthal asymmetries ALT′ were measured at Jefferson Lab using 2.2 and 4.4 GeV longitudinally polarised electrons incident on 4He and 12C targets in the CLAS detector. ALT′ is related to ...the imaginary part of the longitudinal-transverse interference and in quasifree nucleon knockout it provides an unambiguous signature for final state interactions (FSI). Experimental values of ALT′ were found to be below 5%, typically |ALT′|less-than-or-equals, slant3% for data with good statistical precision. Optical model in eikonal approximation (OMEA) and relativistic multiple-scattering Glauber approximation (RMSGA) calculations are shown to be consistent with the measured asymmetries.
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