title: Direct air activation measurements at a 15-MV medical linear accelerator.
abstract: Direct radiometric determination of (14)N (γ, n) (13)N air activation was achieved at a 15-MV medical linear accelerator operating in a high-energy photon mode. (13)N was identified by irradiating a gas-tight Marinelli beaker filled with nitrogen gas and later observing the 10-min half-life of the 511-keV positron-electron annihilation line using high-resolution gamma spectroscopy. Quantitative evaluation of the spectral signal yielded a (13)N production rate of 836.8 ± 32 Bq Gy(-1) in air per 40 × 40 cm(2) field cross section at 100 cm source-surface distance.
authors.affiliation: Physics Department, University of Bremen, Bremen 28359, Germany mohamedrick@gmail.com.
authors.forename: M K
authors.initials: MK
authors.lastname: Saeed
authors.affiliation: Physics Department, University of Oldenburg, Oldenburg 26111, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Poppe
authors.affiliation: Physics Department, University of Bremen, Bremen 28359, Germany.
authors.forename: H W
authors.initials: HW
authors.lastname: Fischer
mesh_terms: D000388:Air / Q000032:analysis*; D000396:Air Pollutants, Radioactive / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis*; D010315:Particle Accelerators; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000396:Air Pollutants, Radioactive