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Status and plans for 2013, CERN NA63

We summarize the status and plans for the future for the CERN NA63 collaboration. Our results for the quantum synchrotron radiation emission, measured in 2009, have been published \cite{Ande12b}. Owing to the close relation between the strong field radiation emission in crystals and beamstrahlung em...

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Detalles Bibliográficos
Autores principales: Andersen, K K, Uggerhoj, U I
Publicado: 2012
Materias:
Acceso en línea:http://cds.cern.ch/record/1483727
Descripción
Sumario:We summarize the status and plans for the future for the CERN NA63 collaboration. Our results for the quantum synchrotron radiation emission, measured in 2009, have been published \cite{Ande12b}. Owing to the close relation between the strong field radiation emission in crystals and beamstrahlung emission at the interaction point of a linear collider, we have in essence tested the approach to calculating the effective luminosity decrease from radiation loss in such machines. A systematic study of the structured target 'resonance' appearing from radiation emission by electrons passing two amorphous foils positioned with separations in the range $10-20000~\mu$m was performed in september 2012. Preliminary results confirm a previously obtained result \cite{Ande12a} that by this method, the formation length - of macroscopic dimensions up to 0.5 mm - for the generation of MeV-GeV radiation from multi-hundred GeV electrons can be \emph{directly} measured. In fact the results obtained allow a distinction between competing theories \cite{Blan97a,Baie99b}, showing the need for a correction-term introduced by Blankenbecler \cite{Blan97b}. With a substantially improved setup compared to the run in 2010 (where the deconvolution of synchrotron radiation prevented results in the most interesting regime below 0.5 GeV), we investigated again the impact of the Landau-Pomeranchuk-Migdal (LPM) effect with 178 GeV electrons, in particular for low-$Z$ targets where a discrepancy between experiment and theory might turn up. Furthermore, measurements with 20 GeV electrons in a Cu target shows no indication of the 'kink-like' structure seen in Migdal's theory (the most widely used) for photon energies around 300 MeV. A proof-of-principle measurement of the efficiency of production for positrons originating from electrons impinging on an axially aligned diamond crystal was also performed, where the production angles and energies can be measured by means of so-called MIMOSA detectors arranged in a magnetic spectrometer configuration with a permanent-magnet-based magnetic dipole.