For about 20 years, quantitative analysis of homogeneous microvolumes has been performed with the aid of correction models which transform into mass concentrations C A the ratio k A between the emerging intensities from the specimen and a standard obtained for a characteristic line of element A:

Quantitative Analysis of Homogeneous or Stratified Microvolumes Applying the Model “PAP”

We review the theory of the electromagnetic interactions between rapidly moving charged particles and the matter through which they pass. The emphasis will be on very massive electric ($\ensuremath{-}100\ensuremath{\le}{Z}_{1}100$) and magnetic ($|g|=137e \mathrm{and} \frac{137e}{2}$) particles moving with relativistic velocities ($\ensuremath{\beta}g0.2$, $\ensuremath{\gamma}l100$). Consideration will be given to both the stopping power of the projectile and to the response of the absorbing medium to the excitation caused by the projectile.

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Theoretical and experimental aspects of the energy loss of relativistic heavily ionizing particles

A review of the program in space-radiation protection at the Langley Research Center is given. The relevant Boltzmann equations are given with a discussion of approximation procedures for space applications. The interaction coefficients are related to the solution of the many-body Schrodinger equations with nuclear and electromagnetic forces. Various solution techniques are discussed to obtain relevant interaction cross sections with extensive comparison with experiments. Solution techniques for the Boltzmann equations are discussed in detail. Transport computer code validation is discussed through analytical benchmarking, comparison with other codes, comparison with laboratory experiments, and measurements in space. Applications to missions to the Moon and Mars are discussed.

Transport Methods and Interactions for Space Radiations

Energy loss, range, path length, time-of-flight, straggling, multiple scattering, and nuclear interaction probability: In two parts. Part 1. For 63 compounds Part 2. For elements 1 ⩽ Z ⩽ 92

The properties of infinitely dilute metal ammonia solutions are interpreted on the basis of Landau's model for electron binding by polarization of the dielectric medium. The electrons are bound in cavities of radius 3.2–3.45 A. The energy levels of the trapped electrons are computed by the variation method using one‐parameter wave functions. It is possible to obtain theoretical values for the heat of solution of the electron and the energy of the 1s→2p transition in agreement with experimental data.The susceptibility of the energy of the electronic transition to temperature cannot be interpreted by the temperature dependence of the dielectric constant only, and it is presumed that the electron cavity radius is temperature dependent.

Energy Levels of Bound Electrons in Liquid Ammonia

Frequency Modulated Cyclotron

Previous experimental data of Sachs and Richardson on the most probable energy loss of 18-Mev protons on passing through thin foils have been used in connection with the theory of Symon to calculate the mean excitation potential $I$. The result for aluminum is $I=164\ifmmode\pm\else\textpm\fi{}3$ electron volts.

Mean Excitation Potentials

The photodisintegration of the deuteron by the gamma-radiation from radioactive sodium ${\mathrm{Na}}^{24}$ has been observed in a cloud chamber filled with deuterium at a pressure of one atmosphere. A sample of NaF was activated by deuteron bombardment in the cyclotron to a gamma-ray strength equivalent to about 12 mg of radium, and was then brought close to the cloud chamber. Pictures were taken with a stereoscopic camera. Of the 100 proton tracks observed on 5000 pictures, only 42 were deemed suitable for range measurement, although the angular orientation of 61 could be determined. The range distribution of these tracks indicates a mean air equivalent range of 4.4 mm, corresponding to a mean energy of 410 kv for the photoprotons. This indicates that the difference between the energy of the ${\mathrm{Na}}^{24}$ gamma-ray and the binding energy of the deuteron is 820\ifmmode\pm\else\textpm\fi{}35 kv. Since the new range energy relation for slow protons has thrown doubt upon the binding energy of the deuteron, we can use the value of 3.00\ifmmode\pm\else\textpm\fi{}0.05 Mev obtained by the Compton recoil method for the energy of the gamma-radiation from ${\mathrm{Na}}^{24}$, and obtain 2.18\ifmmode\pm\else\textpm\fi{}0.07 Mev for the binding energy of the deuteron. The angular distribution of the tracks indicates that the disintegration is predominantly photoelectric, although a small contribution from the photomagnetic effect is not ruled out. A rough calculation from the yield of tracks indicates a cross section for the disintegration of 1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}27}$ ${\mathrm{cm}}^{2}$. The possibilities of the method for the determination of the energy of strong gamma-radiation is discussed.

J. Reginald Richardson

Papers

Frequency Modulated Cyclotron

Mean Excitation Potentials

The Photodisintegration of the Deuteron by the Gamma-Radiation from Na 24

Proton-Proton Scattering at 14.5 Mev