Forward-directed bremsstrahlung of 10- to 30-MeV electrons incident on thick targets of Al and Pb

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Medical Physics; (USA)

DOI:https://doi.org/10.1118/1.596560· OSTI ID:6352623

Faddegon, B A ^[1]; Ross, C K; Rogers, D W.O. ^[2]

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1. Physics Department, Carleton University, Ottawa (Canada)
2. Institute for National Measurement Standards, National Research Council of Canada, Ottawa (Canada)

Bremsstrahlung spectra from thick targets of Al and Pb have been measured absolutely (photons per incident electron) along the beam axis for electrons of 10-, 15-, 20-, 25-, and 30-MeV incident energy. The spectra have a 220-keV low-energy cutoff. The targets were cylinders with nominal thicknesses of 110% of the electron CSDA range. A thin transmission detector, calibrated against a toroidal current monitor, was placed upstream of the target to measure the beam current. The spectrometer was a 20-cm diameter by 25-cm-long cylindrical NaI detector. Measured spectra were corrected for pile-up, background, detector response, detector efficiency, attenuation in materials between the target and detector and the collimator effect. Spectra were calculated using the EGS4 Monte Carlo system for simulating the radiation transport. The simulation model included the small amount of material upstream of the target. This material contributed about 40% of the spectrum, but its presence or absence had little effect on the calculated bremsstrahlung yield. The shapes of the measured and calculated spectra were in excellent agreement. The ratio of the total number of photons in each measured spectrum to those in the corresponding calculated spectrum varied from 0.97{plus minus}0.06 to 1.12{plus minus}0.06, depending largely on the atomic number of the target. Absolute spectral measurements in the literature agreed with our calculations of spectral shape but showed a range of {plus minus}30% in the number of photons per incident electron relative to the calculated values, which is contrary to our result.

• OSTI ID: 6352623
• Journal Information: Medical Physics; (USA), Journal Name: Medical Physics; (USA) Vol. 17:5; ISSN 0094-2405; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

656003* -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
BEAM CURRENTS
BEAMS
BREMSSTRAHLUNG
COLLISIONS
CURRENTS
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRON COLLISIONS
ELEMENTS
ENERGY RANGE
LEAD
LEPTON BEAMS
MEDICINE
METALS
MEV RANGE
MEV RANGE 10-100
MONTE CARLO METHOD
NUCLEAR MEDICINE
PARTICLE BEAMS
RADIATIONS
RADIOLOGY
RADIOTHERAPY
SPECTRA
THERAPY
YIELDS