Chapter 5
Interactions of Beams with Surroundings
M. Brugger, H. Burkhardt, B. Goddard, F. Cerutti, and R. G. Alia
With the exceptions of Synchrotron Radiation sources, beams of accelerated
particles are generally designed to interact either with one another (in the case of
colliders) or with a specific target (for the operation of Fixed Target experiments,
the production of secondary beams and for medical applications). However, in
addition to the desired interactions there are unwanted interactions of the high
energy particles which can produce undesirable side effects. These interactions
can arise from the unavoidable presence of residual gas in the accelerator vacuum
chamber, or from the impact of particles lost from the beam on aperture limits
around the accelerator, as well as the final beam dump. The wanted collisions of the
beams in a collider to produce potentially interesting High Energy Physics events
also reduces the density of the circulating beam and can produce high fluxes of
secondary particles.
All of these unwanted interactions affect the performance of an accelerator, in
desorption of gas from the vacuum system, in reduced lifetime of the circulating
beam, in reduction of the collider luminosity and in background for the detectors.
In this chapter the basic physical phenomena of particle interactions with matter
are described, together with the techniques used to simulate the interaction with
matter. The different types of particle interactions with the surroundings are
elaborated in the context of their adverse effects on the accelerator performance
and the mitigation measures. A full description of the effects and mitigation
measures associated with the vacuum systems of accelerators is given separately
in Chap. 8.
M. Brugger () · H. Burkhardt () · B. Goddard () · F. Cerutti · R. G. Alia
CERN (European Organization for Nuclear Research), Meyrin, Genève, Switzerland
e-mail: Markus.Brugger@cern.ch; Helmut.Burkhardt@cern.ch; Brennan.Goddard@cern.ch
© The Author(s) 2020
S. Myers, H. Schopper (eds.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-34245-6_5
183
Interactions of Beams with Surroundings
M. Brugger, H. Burkhardt, B. Goddard, F. Cerutti, and R. G. Alia
With the exceptions of Synchrotron Radiation sources, beams of accelerated
particles are generally designed to interact either with one another (in the case of
colliders) or with a specific target (for the operation of Fixed Target experiments,
the production of secondary beams and for medical applications). However, in
addition to the desired interactions there are unwanted interactions of the high
energy particles which can produce undesirable side effects. These interactions
can arise from the unavoidable presence of residual gas in the accelerator vacuum
chamber, or from the impact of particles lost from the beam on aperture limits
around the accelerator, as well as the final beam dump. The wanted collisions of the
beams in a collider to produce potentially interesting High Energy Physics events
also reduces the density of the circulating beam and can produce high fluxes of
secondary particles.
All of these unwanted interactions affect the performance of an accelerator, in
desorption of gas from the vacuum system, in reduced lifetime of the circulating
beam, in reduction of the collider luminosity and in background for the detectors.
In this chapter the basic physical phenomena of particle interactions with matter
are described, together with the techniques used to simulate the interaction with
matter. The different types of particle interactions with the surroundings are
elaborated in the context of their adverse effects on the accelerator performance
and the mitigation measures. A full description of the effects and mitigation
measures associated with the vacuum systems of accelerators is given separately
in Chap. 8.
M. Brugger () · H. Burkhardt () · B. Goddard () · F. Cerutti · R. G. Alia
CERN (European Organization for Nuclear Research), Meyrin, Genève, Switzerland
e-mail: Markus.Brugger@cern.ch; Helmut.Burkhardt@cern.ch; Brennan.Goddard@cern.ch
© The Author(s) 2020
S. Myers, H. Schopper (eds.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-34245-6_5
183