Measurements of the spectral location of the structured target resonance for ultrarelativistic electrons

Autor: J. Esberg, S. L. Andersen, A. Mangiarotti, K. K. Andersen, H. D. Thomsen, T. N. Wistisen, P. Sona, R. E. Mikkelsen, T. J. Ketel, Ulrik I. Uggerhøj, Helge Knudsen
Přispěvatelé: History and Social Aspects of Science, (Astro)-Particles Physics
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Zdroj: Andersen, K, Uggerhøj, U I, Mikkelsen, R E, Wistisen, T N, Andersen, S L, Thomsen, H D, Knudsen, H, Esberg, J, Sona, P, Mangiarotti, A & Ketel, T J 2014, ' Measurements of the spectral location of the structured target resonance for ultrarelativistic electrons ', Physics Letters B: Particle Physics, Nuclear Physics and Cosmology, vol. 732, pp. 309 . https://doi.org/10.1016/j.physletb.2014.03.055
Physics Letters B, 732, 309-314. Elsevier
Physics Letters B
Andersen, K & Ketel, T J 2014, ' Measurements of the spectral location of the structured target resonance for ultrarelativistic electrons ', Physics Letters B, vol. 732, pp. 309-314 . https://doi.org/10.1016/j.physletb.2014.03.055
ISSN: 0370-2693
DOI: 10.1016/j.physletb.2014.03.055
Popis: When an ultrarelativistic electron traverses two closely spaced foils, a radiation spectrum 'resonance' appears, arising from the photon formation length extending from one foil, across the gap and into the second foil. Several theoretical approaches yield quite different answers to the spectral location of this 'resonance', and we have therefore in the CERN NA63 collaboration addressed the question experimentally with a 178 GeV electron beam. The experimental technique used - where a variable gap separates two thin gold foils - allows for a direct measurement of a length that is closely related to the distance over which the photon formation takes place. These are the first measurements to observe the gap dependence of the energy of the 'resonance' in the radiation spectrum from a structured target on a truly macroscopic scale up to 0.5 mm. The results are compared with the theory of Baier and Katkov, with both the modified and unmodified theories of Blankenbecler as well as with a naïve, straightforward expectation. Surprisingly, the experiment shows a clear preference for the two latter, comparatively unsophisticated, approaches. © 2014 The Authors.
Databáze: OpenAIRE
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