Presentation on theme: "JRA3 Eurotag report, Dec 20051 Eurotag Development of the European tagged photon facilities. Spokesperson: Ken Livingston, Glasgow Members: Glasgow, Bonn,"— Presentation transcript:
JRA3 Eurotag report, Dec 20051 Eurotag Development of the European tagged photon facilities. Spokesperson: Ken Livingston, Glasgow Members: Glasgow, Bonn, Giessen, INFN, Lund, Mainz, Tuebingen, Kharkov, JLab Award: 600k€ Project Status: ManpowerAll EU funded posts are now filled: 7 postdocs for > 11 man years Workshop A 2 day workshop is organised for March 2006, Glasgow. Timelines On target ( averaged over 6 sub-projects ) DisseminationWeb site: www.nuclear.gla.ac.uk/~kl/Eurotag …. needs updating. Internal reports, conference proceedings
JRA3 Eurotag report, Dec 20052 Linearly polarised photons Standard Technique: Coherent Bremsstrahlung Improvements to degree of polarisation: Better collimation from understanding 2D photon distrib. Improvements to polarimetry: Improve cbrem calculation. Build prototype polarimeter. New possibility: Can Axial Quasi-channeling be used as a source of high energy polarised photons PRELIMINARY RESULT NO! 2D photon beam profile detector
JRA3 Eurotag report, Dec 20053 Beam profiler (Glasgow) 1mrad Prototype detector in MAMI beamlineProfile of MAMI photon beam
JRA3 Eurotag report, Dec 20054 Coherent Brem. Photon Beam 1 st Measurement of 2D photon enhancement for coherent bremsstrahlung. D. Glazier, Glasgow Coh. edge at 200Mev, MAMI @ 855MeV Data already in good agreement with Monte-Carlo (MCB, Tuebingen) Previously only photon energy spectrum Now good data set with 2d photon dist. Currently being used to improve Coherent Bremsstrahlung models under Eugotag (P. Grabmayr, Tuebingen). Paper currently in preparation On coh. peakBelow coh. peak
JRA3 Eurotag report, Dec 20055 Polarimetry Coherent Bremsstrahlung Calculation (eg. Tuebingen) Polarimeter based on e +,e - production Triplet production e+e-e+e- e-e- High analysing power ( > 50% ) Low cross-section, low energy recoil e Tested (GWU) – only 3% analysing power Pair production e+e-e+e- Analysing power 22% Higher cross-section Tested (SC/Jlab) ~ 22% analysing power Used successfully, needs only photon tagger Many free parameters, > 5% systematic error How to detect the pair (or triplet) Magnetic spectrometerMicrostrip detector
JRA3 Eurotag report, Dec 20056 Prototype Polarimeter (Bonn) Big contribution for non-EU members: Kharkov Monte carlo simulations of Pair and Triplet polarimetry solutions (with Bonn) JlabRecent results and analysis of polarimeter for g8b (see below) PRELIMINARY J.Santoro, CUA Asymmetry from Si Microstrip detectors. Average over full Photon energy range Peak > 90% pol. Aim: Build a prototype polarimeter based on simulations and experience from JLab. Small, portable, in-beam, fast (ie better than 5% in order of minutes) K.Livingston, Glasgow
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