Charged Particles In Matter Research Articles

Finding the specific energy losses of charged particles in matter by the method of bombarding absorbers of arbitrary thickness

Finding the specific energy losses of charged particles in matter by the method of bombarding absorbers of arbitrary thickness

Determination of specific energy losses by charged particles in matter

Determination of specific energy losses by charged particles in matter

Search for Possible Geometrical Effect on Stopping Power Measurement

The possibility that the geometrical condition might affect the observed energy loss of heavy charged particles in matter has been considered. The energy losses of 8.78 MeV alpha particles in Al, Cu, Ag and Ta have been measured with good and poor geometries. It has been found that the energy losses observed with good geometry are slightly smaller than those observed with poor geometry. It appears that the geometrical effect may really exist, although the amount of the effect is small and comparable with the statistical uncertainties for the present experimental condition. It has been concluded that this effect is not the origin of the discrepancies between our stopping power data for 7.2 MeV protons and the data of Andersen et al. Some discussions have been made on the comparison of stopping powers for 8.2 MeV alpha particles with those for protons of the same velocity.

On the restricted energy loss of relativistic charged particles in matter

The Bethe-Bloch formula with density effect correction which describes the restricted energy loss of relativistic charged particles in matter is extended to the case when the upper energy transfer in single collisions are of the order or less than the binding energy of atomic inner shell electrons.

Z13-dependent range contributions

Previously derived comprehensive formulas for the Z13 contributions to the ranges of charged particles in matter are amended to apply at high, nonrelativistic particle velocities.Received 11 February 1974DOI:https://doi.org/10.1103/PhysRevA.10.737©1974 American Physical Society

Density Effect in the Ionization Energy Loss of Fast Charged Particles in Matter

Recent experimental work and its theoretical interpretation concerned with the density effect on the energy loss of charged particles in matter is reviewed with particular reference to electrons and muons. Recent proposals that radiative corrections should result in a significant reduction in the ionization loss at very high energies are analyzed in some detail. It is concluded that such an effect has not been substantiated experimentally, and that the predicted radiative corrections are likely to be small (\ensuremath{\sim}1%).

A discussion on ion implantation and hyperfine interactions - The range and energy loss of implanted ions

Since the early experiments of Rutherford at the beginning of the century there have been many measurements of the rate of energy loss, and, in recent years, the distribution profile of ions implanted into more or less amorphous media. The theoretical aspects of atomic penetration were established long ago by Bethe and Bohr, and have been extended over the past decade by Lindhard and his collaborators. Despite this progress, there are still important features concerning the mechanism of the energy loss of charged particles in matter which are poorly understood. There are two contributions to the energy loss, due to nuclear collisions and electronic collisions, and Lindhard has just discussed the degree to which these may be regarded as separable. The first type of collision dominates at low energies and is responsible for most of the angular dispersion of the ions. By developing a unified range theory in which a simple velocity-proportional Thomas─Fermi formula is used for the electronic stopping and a power-law dependence is assumed for nuclear stopping, Lindhard, Scharff & Schiøtt (1963) have provided universal formulae for ion ranges and range straggling. Some sensitive experiments by Jespersgård & Davies (1967) on range distributions of 24 Na, 42 K, 85 Kr and 133 Xe in amorphous Al 2 O 3 show good agreement with these formulae for energies up to about 100 keV. At higher energies the observed ranges were consistently somewhat higher, by as much as 30% at 1 MeV.

Energy loss of charged particles in matter

A new method of determining the differential energy loss of charged excited nuclei in matter is described. The method is based on the velocity dependence of the Doppler shift of the gamma quanta emitted by moving nuclei. No theoretical assumptions concerning the velocity dependence of atomic or nuclear collisions are necessary. The method and mathematical analysis, described in detail, are applied to the energy loss of Li ions emitting gamma quanta of 477 keV in the kinetic energy range between 100 and 800 keV. It is found that the energy loss of Li ions is linearly proportional to the velocity within 2% for several substances ofZ=1 to 74. The small limits of error, which can be obtained, allow an application of this method to questions as e.g. theZ-dependence of the stopping power on the nuclear charge of the stopping material, chemical binding effects, the time dependence of the adjustment of the equilibrium charge of the projectile after nuclear reactions, or the determination of nuclear angular correlations.

Ratio of Atomic Stopping Power of Graphite and Diamond for 1.1-Mev Protons

The theory describing energy loss of heavy charged particles in matter predicts that different physical or chemical forms of the same element will have slightly different stopping powers. Since two different forms of a pure element exhibit the same nuclear scattering cross section, it was possible to measure the relative atomic stopping power of graphic and diamond by observing the yields of backscattered protens from thick targets. The atomic stopping power of graphite was measured to be 1.0604 plus or minus 0.0090 times that of diamond (for 1.1- Mev protons). Using the theoretical density of graphite, a calculation based on this result and Brandt's version of stopping theory yields the result that the molecular polarizability of graphite is 4.9 times thnt of diamond. If this calculation is made using the measured density of graphite, this polarizability ratio is 1.5, in agreement with the theoretical value. (auth)