On the macroscopic formation length for GeV photons

H. D. Thomsen, J. Esberg, K. Kirsebom, H. Knudsen, E. Uggerhøj, U. I. Uggerhøj, P. Sona, A. Mangiarotti, T. J. Ketel, A. Dizdar, M. M. Dalton, S. Ballestrero, S. H. Connell

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Experimental results for the radiative energy loss of 206 and 234 GeV electrons in 5-10 μm thin Ta targets are presented. An increase in radiation emission probability at low photon energies compared to a 100 μm thick target is observed. This increase is due to the formation length of the GeV photons exceeding the thickness of the thin foils, the so-called Ternovskii-Shul'ga-Fomin (TSF) effect. The formation length of GeV photons from a multi-hundred GeV projectile is through the TSF effect shown directly to be a factor 1010 longer than their wavelength.

Original languageEnglish
Pages (from-to)323-327
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number4-5
Publication statusPublished - 2 Mar 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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