W Values of Protons Slowed Down in Molecular Hydrogen
| Autor: | B. Grosswendt, Woon Yong Baek, G. Willems |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Nuclear reaction
Range (particle radiation) Radiation Materials science Radiological and Ultrasound Technology Hydrogen Proton Public Health Environmental and Occupational Health chemistry.chemical_element General Medicine Secondary electrons Ion chemistry Ionization Stopping power (particle radiation) Radiology Nuclear Medicine and imaging Atomic physics |
| Zdroj: | Radiation Protection Dosimetry. 70:37-46 |
| ISSN: | 1742-3406 0144-8420 |
| DOI: | 10.1093/oxfordjournals.rpd.a031979 |
| Popis: | For protons completely slowed down in molecular hydrogen, the mean energy W required for forming an ion pair has been studied in the energy range between 1 keV and 10 MeV, partly by measurements and partly by calculations. The experimental W values were determined for collimated beams of monoenergetic protons with energies between 1 keV and 100 keV by measuring the positive ion yield they produce in a plane-parallel ionisation chamber filled with hydrogen gas. The calculated W values were determined (i) using the Monte Carlo method for energies between 1 keV and 100 keV and (it) within the framework of an analytical model based on the continuous slowing down approximation in the energy range between 1 keV and 10 MeV, taking into account the proton stopping power, the effect of charge exchange, the different ionisation cross sections for protons and neutral hydrogen particles, and the contributions of secondary electrons to the total ionisation yield. The complete data set for W as a function of energy shows the typical decrease with increasing energy in the region of up to about 5 keV, followed by a smoothly oscillating shape for higher energies. It can be assumed that the oscillating shape of W as a function of energy is mainly caused by charge-exchange processes and by the ionisation yield contribution of secondary electrons. |
| Databáze: | OpenAIRE |
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