LPM effect in cosmic-ray electron observations with emulsion chambers

Kenji Yoshida, Tadashi Kobayashi, Jun Nishimura

研究成果: Conference article査読


We have performed a series of cosmic-ray electron + positron observations using balloon-borne emulsion chambers since 1968, together with electron beam tests at CERN-SPS. In emulsion chamber experiments, we can measure the location of shower tracks in each emulsion plate with a precision of 1 μm. Because of the high position resolution, we can identify the first electron-positron pairs of electron-induced showers. The LPM effect predicts a reduction of amplitude for bremsstrahlung photon emission by a high-energy electron. It causes the optical depth of the first electron-positron pair to increase. From the measurements of the first pair depths with 200 GeV and 250 GeV beam electrons at CERN, and cosmic ray electrons + positrons from 400 GeV to 3 TeV (on average at 900 GeV), we found direct evidence of suppression of the bremsstrahlung cross section due to the LPM effect. In this work, we present the experimental results compared to analytic approximations and Monte-Carlo simulations.

ジャーナルJournal of Physics: Conference Series
出版ステータスPublished - 2019 3月 10
イベント26th Extended European Cosmic Ray Symposium, E+CRS 2018 - Barnaul-Belokurikha, Russian Federation
継続期間: 2018 7月 62018 7月 10

ASJC Scopus subject areas

  • 物理学および天文学(全般)


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