Results on the coherent interaction of high energy electrons and photons in oriented single crystals

A. Apyan*, R. O. Avakian, B. Badelek, S. Ballestrero, C. Biino, I. Birol, P. Cenci, S. H. Connell, S. Eichblatt, T. Fonseca, A. Freund, B. Gorini, R. Groess, K. Ispirian, T. J. Ketel, Yu V. Kononets, A. Lopez, A. Mangiarotti, B. Van Rens, J. P.F. SellschopM. Shieh, P. Sona, V. Strakhovenko, E. Uggerhøj, U. I. Uggerhøj, G. Unel, M. Velasco, Z. Z. Vilakazi, O. Wessely

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The CERN-NA-59 experiment examined a wide range of electromagnetic processes for multi-GeV electrons and photons interacting with oriented single crystals. The various types of crystals and their orientations were used for producing photon beams and for converting and measuring their polarisation. The radiation emitted by 178 GeV unpolarised electrons incident on a 1.5 cm thick Si crystal oriented in the Coherent Bremsstrahlung (CB) and the String-of-Strings (SOS) modes was used to obtain multi-GeV linearly polarised photon beams. A new crystal polarimetry technique was established for measuring the linear polarisation of the photon beam. The polarimeter is based on the dependence of the coherent pair production (CPP) cross section in oriented single crystals on the direction of the photon polarisation with respect to the crystal plane. Both a 1 mm thick single crystal of Germanium and a 4 mm thick multi-tile set of synthetic Diamond crystals were used as analyzers of the linear polarisation. A birefringence phenomenon, the conversion of the linear polarisation of the photon beam into circular polarisation, was observed. This was achieved by letting the linearly polarised photon beam pass through a 10 cm thick Silicon single crystal that acted as a "quarter wave plate" (QWP) as suggested by Cabibbo et al.

Original languageEnglish (US)
Pages (from-to)128-137
Number of pages10
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume234
Issue number1-2
DOIs
StatePublished - May 2005

Keywords

  • Coherent Bremsstrahlung
  • Polarimetry
  • Polarised photons
  • Single Crystal

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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