In the Martian ionosphere the dominant solar ionization products are O+ and CO2+. These ions are rapidly converted to O2+ by ion neutral reactions resulting in O2+ as the dominant ion. As O2+ has a lower ionization potential, each reaction results in approximately 1.2 eV of energy to be shared by the reaction products. The kinetic energy given to the O2+ will affect the ion temperatures. Calculations have been made of the ion heating rates and temperatures which result from the degradation of these energetic ions for various energy production distributions for conditions similar to those encountered by Viking 1. It is shown that the thermalization of the energetic O2+ can greatly increase the ion temperatures above 200 km compared to those calculated using only the ambient electron heating source. The effect of small horizontal magnetic fields, as predicted by current solar wind interaction models on the ion thermal balance was also investigated. These fields act to restrict the ion thermal conductivity and thus also increase the upper altitude ion temperatures. The combination of the heating by the energetic O2+ and the effect of the magnetic field provide a partial agreement with the Viking 1 measurements.

NEEDof protons, and perhaps the parameters in the leveldensity formula need to be specially adjusted for this situation. It would seem that much more experimental evidence needs to be obtained to discover systematics which may exist. CONCLUSIONThe results of the present experiment suggest that the statistical theory of nuclear reactions describes adequately, at least, the shapes of the energy spectra of light particles from nitrogen-induced reactions at zero degrees. Angular distributions and experiments onThe scattering of 18-Mev alpha particles from neon, argon, and xenon was studied with a multiplate reaction chamber. The scattered particles were denned within an rms angular width of 0.45° by a system of slit pairs, spaced every 2^° from 10° to 170°. The elastic scattering from neon and argon show the pronounced maxima and minima characteristic of diffraction scattering but are equidistant in } not sin(<£/2). The ratio to Rutherford scattering varies as much as 25-fold between successive maxima and minima in the case of neon, the well-defined structure indicating a small mean free path for absorption of alpha particles in the nucleus. Nuclear interaction radii calculated by the formula 2&i?A[sin(0/2)] = 7r were found to be 6.36X10 -13 cm for neon and 6.95 XlO -13 cm for argon. Xenon, investigated chiefly for control purposes, showed no definite deviation from Rutherford INTRODUCTIONT HERE has been renewed interest in the scattering of alpha particles from nuclei following the establishment by Farwell and Wegner 1 of a pronounced variation with energy of the scattering cross section for heavy nuclei. They found that the ratio of the observed differential scattering cross section to the Rutherford cross section,

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Angular distributions have been measured for the reactions C 12 (He 3 ,^)N 14 and C 12 (He 3 ,d)N 13 using the cyclotron 14-Mev He 3 beam. Assuming that the (He 3 ,^) reaction proceeds by the stripping of a deuteron in either its singlet or triplet state from the He 3 nucleus, reasonable fits to the angular distributions were obtained using a [iz,((>o)3 2 dependence. For the transitions to the 1 + , T=0 ground and second excited states of N 14 , L = 2, fo = 6.0f, and L = 0, r 0 = 5.7f, respectively. This is in accord with a predominant 3 Z>i ground state and predominant 3 Si second excited state configuration for N 14 . For the transition to the 0 + , T= 1 first excited state, L = 0 and fo = 5.7f. Butler's stripping theory for the (He 3 ,d) reaction with l p ==l and r 0 = 5.8f accounts reasonably well for the C 12 (He 3 ,d)N 13 angular distribution.

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