Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Jülich, LANL/Los Alamos, ...LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au were investigated. Residual nuclides were measured by X- and γ-spectrometry and by Accelerator Mass Spectrometry (AMS). The measured cross sections were corrected for interfering secondary particles in experiments with primary proton energies above 200 MeV. Our consistent database covers presently ca 550 nuclear reactions and contains nearly 15000 individual cross sections of which about 10000 are reported here for the first time. They provide a basis for model calculations of the production of cosmogenic nuclides in extraterrestrial matter by solar and galactic cosmic ray protons. They are of importance for many other applications in which medium energy nuclear reactions have to be considered ranging from astrophysics over space and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification. The experimental data are compared with theoretical ones based on calculations using an INC/E model in form of the HETC/KFA2 code and on the hybrid model of preequilibrium reactions in form of the AREL code.
Absolute cross sections, energy spectra, and angular distributions have been measured for
1,2,3H,
3,4,6He,
6,7,8,9Li and
7,9,10Be isotopes produced in 1.2 GeV proton-induced spallation reactions with ...targets between Al and Th. Results of simulation calculations with the intra-nuclear cascade code INCL2.0 coupled to the statistical model GEMINI are in good agreement with these data, as to charged-particle evaporation, mean excitation energy, and mean linear momentum transfer. The pre-equilibrium emission of composite particles, not accounted for in these simulations, however, typically contributes to the total production of composite particles by 40–60% for
2H and
3He, 20–40% for
3H, 5–20% for
4He, and about 15–25% for Li and Be. The composite pre-equilibrium particles together carry off a mean energy of up to 50 MeV, i.e., about 30% compared to the mean energy released by particle evaporation. For deuterons, pre-equilibrium emission is shown to be well described by surface coalescence while definitely other mechanisms are required for
4He and heavier clusters.
Neutron experimental data relevant to the design of the target of neutron spallation sources are presented and discussed. The data include the reaction cross-sections for W, Hg and Pb investigated ...with 0.4, 0.8, 1.2, 1.8 and 2.5 GeV proton beams as well as the neutron production, neutron multiplicity distribution, as determined event per event using a high-efficiency detector. The production as a function of target material is investigated for both thin (with a single reaction) and thick targets (multiple reactions). Comparisons are made with the predictions of a high-energy transport code.
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.
Reaction cross sections and production cross sections for neutrons, hydrogen, and helium have been measured for 1.2, 1.8 GeV p+Fe, Ni, Ag, Ta, W, Au, Pb and U and are compared with different ...intra-nuclear-cascade- combined with evaporation-models. Agreement for neutrons and considerable differences for light charged particles are observed between experiment and calculation as well as between different models. The discrepancies are associated with specific deficiencies in the models. The exclusive data measured with two 4π-detectors for neutron and charged particle detection allowed furthermore a systematic comparison of observables characteristic of different stages of the temporal evolution of a spallation reaction: inelastic collision probability, excitation energy distribution, pre-equilibrium emission, and inclusive production cross sections.
The cross section for the production of ω mesons in proton–proton collisions has been measured in a previously unexplored region of incident energies. Cross sections of σ=(7.5±1.9) μb and ...σ=(30.8±3.4) μb (with 20% systematic uncertainties) were extracted at ϵ=92 MeV and 173 MeV excess energy above the ω threshold, respectively. The angular distribution of the ω at ϵ=173 MeV is strongly anisotropic, demonstrating the importance of partial waves beyond pure s-wave production at this energy.
The emission of composite-particles is studied in the reaction
p+Au at
E
p
=2.5 GeV, in addition to neutrons and protons. Most particle energy spectra feature an evaporation spectrum superimposed on ...an exponential high-energy, non-statistical component. Comparisons are first made with the predictions by a two-stage hybrid reaction model, where an intra-nuclear cascade (INC) simulation is followed by a statistical evaporation process.The high-energy proton component is identified as product of the fast pre-equilibrium INC, since it is rather well reproduced by the INCL2.0 intra-nuclear cascade calculations simulating the first reaction stage. The low-energy spectral components are well understood in terms of sequential particle evaporation from the hot nuclear target remnants of the fast INC. Evaporation is modeled using the statistical code GEMINI. Implementation of a simple coalescence model in the INC code can provide a reasonable description of the multiplicities of high-energy composite particles such as
2–3H and
3He. However, this is done at the expense of
1H which then fails to reproduce the experimental energy spectra.
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