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.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
— A purely physical model is presented describing the depth‐ and size‐dependence of the production of cosmogenic nuclides in meteoroids with radii up to 85 cm and in planetary surfaces by galactic ...cosmic ray protons. The model is based on Monte Carlo calculations of the intra‐ and internuclear cascades, by which depth‐ and size‐dependent spectra of primary and secondary protons and of secondary neutrons are derived, and on experimental and theoretical thin‐target cross sections of the underlying nuclear reactions. Model calculations are presented for production rates of 53Mn, 26Al, 22Ne, and 21Ne in H‐ and L‐chondrites and of 53Mn and 26Al in lunar surface material and compared with experimental data. From the analysis of 53Mn and 26Al in the Apollo 15 lunar drill core and in the L‐chondrite Knyahinya GCR p‐spectra and integral particle fluxes at 1 A.U. and in the meteoroid orbits averaged over the last 10 Ma are derived. An analysis of experimental depth profiles in four H‐ and L‐chondrites demonstrates, that the new model is well capable of describing depth‐ and size‐dependences of production rates of cosmogenic nuclides. Moreover, it is possible to determine exposure ages for these meteorites on the basis of the theoretical 21Ne production rates. The model calculations further explain the depth‐ and size‐dependence of 22Ne/21Ne‐ratios and the dependences on these ratios of 21Ne, 26Al and 53Mn production rates. The future requirements for model calculations of cosmogenic nuclide production rates in extraterrestrial matter are outlined.
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.
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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.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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