High-energy Secondary Electrons Research Articles

Estimation of dose to the urinary bladder and to the gonads

The cellular microdosimetry parameters including the cellular S-value and the single-event specific energy distribution for alpha particles and electrons are important in radiation dosimetry and biology. These parameters may be used to determine the relative biological effectiveness of radiations in the boron neutron capture therapy. In the present work, such parameters were calculated for different source to target region combinations, i.e. cell surface, cytoplasm, nucleus and cell. Calculations were made using a semi-analytical model that simulated the emission of alpha particles or electrons by the Monte Carlo method and calculated the energy imparted to the target volume by the analytical method. Delta particle equilibrium and partial delta particle equilibrium were applied to alpha particles and electrons, respectively. Range–energy relations were employed to determine the incident and emerging energies of the primary particles. For electrons, the fraction in the energy loss resulting from the generation of bremsstrahlung and high-energy secondary electrons was estimated. The energy loss straggling of electrons entering and leaving a target volume was also estimated. Calculated cellular S-values were compared to corresponding data of the MIRD Committee. Calculated single-event specific energy distributions were also compared to results calculated using the Penelope code.

Plasma Diagnostics and Energy Transport of a dc Discharge Used for Sputtering

An investigation of plasma properties and energy-transport mechanisms within a dc anomalous glow discharge has been conducted, with particular reference to those processes operating in the vicinity of the anode. The objective of this work was to obtain more quantitative information about the species in the plasma contributing to the heating of substrates located on the anode during sputtering. Techniques employed in this study involved the use of Langmuir probes for the detection of low-energy species, of an electrostatic analyzer for detection of high-energy species within the plasma, and of temperature-sensitive probes for energy-flux measurements. The negative glow of the plasma was found to contain two electron-energy distributions, one of density ∼2×1010 cm−3 and mean energy ∼0.6 eV, and the other ∼2×108 cm−3 and ∼6 eV energy. A low-energy positive-ion population approximately balanced these densities. Under all operating conditions, the plasma potential was found to be a few volts positive with respect to ground. Energy-flux measurements at the anode showed that the main source of energy was not from these populations in the plasma, however. Further examination of the discharge, using the electrostatic analyzer, revealed the presence of high-energy secondary electrons emitted at, or in, the vicinity of the cathode. Many of these electrons penetrated to the anode with the full fall of cathode potential, and it was found that they were the cause of the initial rapid rise of substrate temperature on commencement of sputtering. Radiation from uncooled cathodes was also a source of energy at the anode, once equilibrium temperatures had been approached.

Calculation of High-Energy Secondary Electron Emission

The emission of high-energy secondary electrons from thin targets of low atomic number has been calculated. The targets are assumed to be bombarded with 25-MeV electrons, 600-kVp x rays, and prompt fission gamma radiation. The results give maximum efficiency of high-energy secondary electron emission of 8% for 25-MeV electrons, 0.30% for prompt fission gamma radiation, and 0.05% for 600-kVp x rays.

Some features of the electron energy spectrum in the Ke3 decay process

It is shown that there exist some characteristic features in the theoretical energy spectrum of the electrons in K/sub e3/ decay, and the experimental analysis of these simple features seems to be easier than the investigation for the correlation with the pion energy. The electron-pion energy correlation function is given. The ratio of high-energy secondary electrons to lowenergy electrons is investigated. (W.D.M.)

High-Energy Secondary Electrons

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