Study of Thick-Target X-Ray Spectra Using Photonuclear Reactions.

摘要

Megavoltage bremsstrahlung spectra which are produced in thick targets were investigated using photonuclear reactions. Ratios of photonuclear yields in teflon and in K2SiF6 were obtained that serve as sensitive indexes of thick target x-ray quality and endpoint energy in the energy range from about 14 to 30 MeV. Because thick target bremsstrahlung spectra have never before been used in the determination of photonuclear reaction cross sections, a numerical analysis computer calculation of thick target bremsstrahlung spectra was written to approximate the spectra of x-rays produced in thick targets of clinical electron linear accelerators and examine the feasibility of using such spectra for cross section determinations. The spectra obtained by computer simulation were used to calculate the photonuclear cross section of the 27 A1(gamma, 2p)Superscript 25Na reaction from 25 to 33 MeV. The calculated cross section is reported and is compared to a previously reported cross section and to a cross section calculated using thin target bremsstrahlung spectra. Analyses of the results obtained indicate that thick target x-ray spectra can be used for photonuclear reaction cross section determination.