Bremsstrahlung scattering calculations for the beam stops and collimators in the APS insertion-device beamlines

Technical Report · Thu Dec 01 04:00:00 EST 1994

DOI:https://doi.org/10.2172/10114862· OSTI ID:10114862

Job, P K; Haeffner, D R; Shu, D

Bremsstrahlung is produced in the APS storage ring by the interaction of positrons with the residual gas molecules in the vacuum chamber of the storage ring. The bremsstrahlung production causes a serious challenge in shielding the insertion-device beamlines because the entire straight section (15 meters) is in the line of sight of the beamline. The radiation emerges in a narrow cone tangential to the beam path with the characteristic emission angle 1/{gamma}, where {gamma} is E/mc{sup 2} which is the ratio of the kinetic energy to the rest mass for the positrons. This high-energy gamma radiation has an approximate 1/E spectrum with the maximum energy extending up to the particle energy (7 GeV for the APS). Bremsstrahlung, being high-energy photons, produces an electromagnetic shower when it encounters the beamline elements. A beamline element not thick enough to fully contain an electromagnetic shower can cause considerable scatter of the high-energy bremsstrahlung radiation. The low-energy component of the bremsstrahlung can also be scattered and create high dose rates in the first-optical and white-beam enclosures. The fully developed electromagnetic shower will have a photon spectrum almost independent of the material. The electromagnetic showers in the high-Z materials can also produce photoneutrons. This note reports the summary of EGS4 calculations performed on bremsstrahlung scattering from different beamline components in a typical APS insertion-device beamline. The related recommendations for shielding are also given. The shielding criterion adopted is a total dose rate of 2.5{mu}Sv/h (0.25 mrem/h) at 30 cm from the shield.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 10114862
• Report Number(s): ANL/APS/TB--20; ON: DE95005471
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200
430303
ADVANCED PHOTON SOURCE
BEAM DUMPS
BEAM DYNAMICS, FIELD CALCULATIONS, AND ION OPTICS
BEAM TRANSPORT
BREMSSTRAHLUNG
CALCULATION METHODS
COLLIMATORS
EXPERIMENTAL FACILITIES AND EQUIPMENT
SCATTERING
SHIELDING