A purely physical model for the simulation of cosmic ray particle interactions with the Earth's atmosphere and subsequent production and transport of secondary particles is presented. Neutron and proton spectra as a function of the coordinate in the atmosphere were calculated using a GEANT / MCNP-based code system. The calculated neutron fluxes are in good agreement with experimental data based on neutron monitor measurements. These fluxes, together with experimental or evaluated cross sections, were used to calculate the production rates of 3 H, 7 Be, 10 Be 14 C, and 36 Cl. The dependencies of these production rates on solar activity and geomagnetic field intensity were investigated in detail. The obtained production rates agree well with most published experimental and theoretical values. Possible reasons for some differences are discussed.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1998JD200091

Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere

The surface of the Moon is a critical boundary that shapes our understanding of the Moon as a whole. All geologic mapping and remote sensing techniques utilize only the outermost portion of the Moon. Before leaving the Moon for study in our laboratories, all lunar samples that have been studied existed at or very near the surface. With the exception of the deeply probing geophysical techniques, our understanding of the interior of the Moon is derived from surficial, but not superficial, information, coupled with boundary of the lunar crust, it is the lower boundary layer of the tenuous lunar atmosphere and constitutes both a source and a sink for atmospheric gases. The surface is also where the Moon interacts with the space environment, causing changes in the physical nature of lunar materials, and provides a laboratory for the study of processes that occur on all airless bodies.

The data obtained remotely by the Galileo, Clementine, and Lunar Prospector missions, as well as data derived from lunar meteorites, have resulted in major changes to our understanding of global distributions of chemistry and rocks. This chapter summarizes the current understanding of this critical interface, the surface of the Moon, in its role as the lower boundary of the lunar atmosphere, the upper boundary of the crust, and the window through which we view, through remote sensing, the composition of the crust and the history of the Moon. In this post-Lunar Prospector time, the view of the Moon has changed, lending new perspectives to lunar samples and lunar processes. But the New View will likely remain in flux as we continue to digest the results from these recent space missions and move forward to a new era of lunar exploration.

Despite the freshness of our perspective, this is an important moment to capture, …

Understanding the Lunar Surface and Space-Moon Interactions

The light fragment production reactions for 10 MeV to 3 GeV protons incident on 16 O , 27 Al , nat Fe , 93 Nb and nat Ag are analyzed by a combination of an intranuclear cascade model and a generalized evaporation model which includes light nuclei up to Mg as ejectiles. The results suggested that an evaporation process is a significant source of light fragment lighter than or equal to Be produced from targets heavier than O.

Statistical analysis of light fragment production from medium-energy proton induced reactions

The light fragment production reactions for 10 MeV to 3 GeV protons incident on O-16, Al-27, Fe, Nb-93, and Ag are analyzed by a combination of an intranuclear cascade model and a generalized evaporation model which includes light nuclei up to Mg as ejectiles. It is concluded that evaporation is the dominant process by which particles lighter than or equal to Be are produced from targets heavier than O.

Statistical analysis of light fragment production from medium energy proton-induced reactions

(Received 1999 April 5; accepted in revised form 1999 October 12) ~~ ~~ Abstract-We present a purely physical model for the calculation of depth- and size-dependent production rates of cosmogenic nuclides by galactic cosmic-ray (GCR) particles. Besides the spectra of primary and secondary particles and the excitation hnctions of the underlying nuclear reactions, the model is based on only one free parameter-the integral number of GCR particles in the meteoroid orbits. We derived this value from analysis of radionuclide data in Knyahinya. We also show that the mean GCR proton spectrum in the meteoroid orbits has been constant over about the last 10 Ma. For the major target elements in stony meteoroids, we present depth- and size-dependent production rates for loBe, 14C, 26A1, 36Cl, and 53Mn as well as for the rare gas isotopes 3He, ZoNe, 21Ne, 22Ne, 36Ar, and 38Ar. The new data differ from semi- empirical estimates by up to a factor of 4 but agree within -20% with results obtained by earlier parametric or physical approaches. The depth and size dependence of the shielding parameter 22Ne/21Ne and the correlations 26AI vs. loge, 26AI vs. 53Mn, loBe/zlNe vs. 22Ne/21Ne, and 36Ar vs. 36Cl for deciphering preatmospheric sizes, shielding depths, terrestrial residence times, and exposure histories are also discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.2000.tb01775.x

The production of cosmogenic nuclides in stony meteoroids by galactic cosmic‐ray particles

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/Julich, 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.

Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements c, n, o, mg, al, si, ca, ti, v, mn, fe, co, ni, cu, sr, y, zr, nb, ba and au

H. Reinhardt

Papers

Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements c, n, o, mg, al, si, ca, ti, v, mn, fe, co, ni, cu, sr, y, zr, nb, ba and au