Beamstrahlung and QED backgrounds at future linear colliders [Thesis]

Technical Report · Mon Oct 01 04:00:00 EDT 1990

DOI:https://doi.org/10.2172/6078574· OSTI ID:6078574

Schroeder, Daniel V. ^[1]

---

1. Stanford Univ., CA (United States)

This dissertation is a detailed study of several aspects of beamstrahlung and related phenomena. The problem is formulated as the relativistic scattering of an electron from a strong but slowly varying potential. The solution is readily interpreted in terms of a classical electron trajectory, and differs from the solution of the corresponding classical problem mainly in the effect of quantum recoil due to the emission of hard photons. When the general solution is expanded for the case of an almost-uniform field, the leading term is identical to the well-known formula for quantum synchrotron radiation. The first non-leading term is negligible in all cases of interest where the expansion is valid. In applying the standard synchrotron radiation formula to the beamstrahlung problem, the effects of radiation reaction on the emission of multiple photons can be significant for some machine designs. Another interesting feature is the helicity dependence of the radiation process, which is relevant to the case where the electron beam is polarized. The inverse process of coherent electron-positron pair production by a beamstrahlung photon is a potentially serious background source at future colliders, since low-energy pairs can exit the bunch at a large angle. Pairs can also be produced incoherently by the collision of the two photons, either real or virtual. The rates, spectra, and angular distributions for both the coherent and incoherent processes are estimated here. At a 1/2 TeV machine the incoherent process will be more common, resulting in roughly 10⁶ pairs per bunch crossing. One member of each pair is always pushed outward, at an angle determined by its energy, by the field of the oncoming bunch. In addition, a small number of pairs are initially produced with a comparable or larger angle.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 6078574
• Report Number(s): SLAC--371; SLAC-R--371; ON: DE91006804
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200* -- Particle Accelerators-- Beam Dynamics
Field Calculations
& Ion Optics
645100 -- High Energy Physics-- Particle Interactions & Properties-Experimental
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATORS
BEAM BUNCHING
BEAM DYNAMICS
BEAM-BEAM INTERACTIONS
BEAMS
BREMSSTRAHLUNG
ELECTRODYNAMICS
ELECTROMAGNETIC RADIATION
ELECTRON-POSITRON INTERACTIONS
FIELD THEORIES
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LINEAR ACCELERATORS
LINEAR COLLIDERS
PAIR PRODUCTION
PARTICLE INTERACTIONS
POLARIZED BEAMS
QUANTUM ELECTRODYNAMICS
QUANTUM FIELD THEORY
RADIATIONS
SYNCHROTRON RADIATION