### An Accurate Measurement of the Landau-Pomeranchuk-Migdal EffectAn Accurate Measurement of the Landau-Pomeranchuk-Migdal Effect

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 Author Anthony, P. L. ♦ Becker-Szendy, R. ♦ Bosted, P. E. ♦ Cavalli-Sforza, M. ♦ Keller, L. P. ♦ Kelley, L. A. ♦ Klein, S. R. ♦ Niemi, G. ♦ Perl, M. L. ♦ Rochester, L. S. ♦ White, J. L. Source United States Department of Energy Office of Scientific and Technical Information Content type Text Language English
 Subject Keyword PHYSICS ♦ PARTICLES ♦ BREMSSTRAHLUNG ♦ MIGDAL THEORY ♦ RELATIVISTIC RANGE ♦ CROSS SECTIONS ♦ PHOTONS ♦ ELECTRON REACTIONS ♦ GOLD 197 TARGET ♦ CARBON 12 TARGET Abstract In the 1950s, Landau, Pomeranchuk, and Migdal (LPM) predicted that the cross section for bremsstrahlung from highly relativistic particles in dense media would be suppressed due to interference between amplitudes of nearby interactions. We have measured the production rates of 5 to 500 MeV photons from 8 and 25 GeV electrons traversing thin gold and carbon targets. We observe, to within 5% accuracy, suppression at the level predicted by Migdal. For extremely thin targets, we observe edge effects where the LPM suppression is reduced near the edges of the targets. We also point out the imprecise foundation of the LPM theory. ISSN 00319007 Educational Use Research Learning Resource Type Article Publisher Date 1995-09-04 Publisher Department Stanford Linear Accelerator Center Publisher Place United States Journal Physical Review Letters Volume Number 75 Issue Number 10 Organization Stanford Linear Accelerator Center