CERN Accelerating science

Preprint
Report number	hep-ex/0406026 ; NUHEP-EXP-2-007 ; NU-HEP-EXP-2-007
Title	Measurement of Coherent Emission and Linear Polarization of Photons by Electrons in the Strong Fields of Aligned Crystals
Related title	ELECTRON
Author(s)	Apyan, A. ; Avakian, R.O. ; Badelek, B. ; Ballestrero, S. ; Biino, C. ; Birol, I. ; Cenci, P. ; Connell, S.H. ; Eichblatt, S. ; Fonseca, T. ; Freund, A. ; Gorini, B. ; Groess, R. ; Ispirian, K. ; Ketel, T.J. ; Kononets, Yu.V. ; Lopez, A. ; Mangiarotti, A. ; van Rens, B. ; Sellschop, J.P.F. ; Shieh, M. ; Sona, P. ; Strakhovenko, V. ; Uggerhoj, E. ; Uggerhj, Ulrik Ingerslev ; Unel, G. ; Velasco, M. ; Vilakazi, Z.Z. ; Wessely, O. NA59 Collaboration  Mostra tots els 29 autors
Publication	2004
Imprint	9 Jun 2004
Number of pages	16
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN SPS ; NA59
Abstract	We present new results regarding the features of high energy photon emission by an electron beam of 178 GeV penetrating a 1.5 cm thick single Si crystal aligned at the Strings-Of-Strings (SOS) orientation. This concerns a special case of coherent bremsstrahlung where the electron interacts with the strong fields of successive atomic strings in a plane and for which the largest enhancement of the highest energy photons is expected. The polarization of the resulting photon beam was measured by the asymmetry of electron-positron pair production in an aligned diamond crystal analyzer. By the selection of a single pair the energy and the polarization of individual photons could be measured in an the environment of multiple photons produced in the radiator crystal. Photons in the high energy region show less than 20% linear polarization at the 90% confidence level.
Other source	Inspire