Eurotag Development of the European Tagged photon facilities. Spokesperson: Ken Livingston, Glasgowurl: Upgrade to 250MeV New Coherent Brem New Tagger Crystal Barrel upgrade Coherent Brem. Crystal Ball Upgrade to 1.5GeV Upgrade of Tagger Upgrade of C. Brem Beam intensity x2 Lin. Pol 96% Members: Glasgow, Bonn, Giessen, INFN, Lund, Mainz, Tuebingen, Kharkov, JLab Bremsstrahlung facilities Improvements to provision of linearly polarised photon beams Award: 600k€

Eurotag objectives Photon Tagging Develop prototype focal plane modules (amplifier + discriminator + coincidence)‏ Linearly Polarised Photons Develop prototype photon beam profile detector for the investigation of quazi- channeling radiation as source of high energy polarised photons. Develop linearly polarised photon beam at MAXLab, Lund. Develop software toolkit for polarised photon beams. Develop “proof of principle polarimeter” for linearly polarised photons. Develop polarimetry for double polarisation experiments. Peak > 90% pol. Glasgow tagging spectrometer upgrade at MAMI Coherent bremsstrahlung photons

Linearly polarised photons    P cos 2 

Linearly polarised photons: physics programme “Stand alone measurements” Photon asymmetry Σ Eg. γ p → K + Λ 0 → K + π - p For double polarisation observables Eg. Pseudoscalar meson “Complete measurement” Many expts across world requiring Linear Pol.

Coherent bremsstrahlung Tagging spectrometer with high rate, good energy and timing resolution High precision goniometer Software for alignment, running experiments Polarimetry Alternative methods (eg. Quasi channeling radiation)‏

Prototype tagger electronics J. Annand, Glasgow PMT Voltage divider x10 amplifier Dual threshold discriminator Coincidence logic PECL Outputs for Catch standard. Prototyped by Glasgow (J. Annand) and Zott Ltd (Edinburgh)‏ Prototype completed in spring boards made by Zott. Recently installed at MAMI. Will also be use for new focal plane detector at MAXLab Upgraded Glasgow Tagger in Mainz

Software: alignment and setup (Ken Livingston, Glasgow)‏ Alignment technique developed Software tools available Already the “industry standard” Used in MAMI, Mainz ELSA, Bonn CLAS, Jefferson Lab GlueX, Jefferson Lab MAXLab, Lund “A device called a goniometer tilts the diamond, much like a lady turning her hand to admire the sparkle of a new ring.”

Software: online control Ken Livingston, Glasgow Site independent online control tools developed. Suitable for non-expert shift workers

Polarimetry: from coherent bremsstrahlung theory P. Grabmayr, Tuebingen Analytic and Monte-carlo techniques developed Software tools available Already the “industry standard” Used in MAMI, Mainz ELSA, Bonn CLAS, Jefferson Lab GlueX, Jefferson Lab MAXLab, Lund Measure polarization to <5% Only requires a photon tagger Recent improvements from 2D measurements Can a “real” polarimeter do any better ?

Pair production simulations by Kharkov group Polarimeter built and tested at Sping8, recently tested at Jlab e+e-e+e- Polarimeter to be based on Jlab design Microstrip detectors, or pixel detectors (Atlas group) Bonn student completed 10 months exchange in Glasgow now to be full time in Bonn. Polarimetry: from pair (e +,e - ) production H.Schmieden, Bonn Well described by QED, but experimentally difficult – small opening angle PRELIMINARY J.Santoro, CUA Peak > 90% pol. K.Livingston, Glasgow

Use reaction with a known photon asymmetry Can be high statistics Very good relative monitor of polarization Combined beam, target polarization. Non-indpendent – depends on specific expt Need very good systematics or calibration Awaiting MAMI polarized target and polarised photon beam in 2 nd half of 2007 Polarimetry: from hadronic reaction R. Beck, Mainz -> Bonn Recent preliminary results from JLab (g8b)‏ Proton target Back to back charge particles in Start Counter Atomic or hardonic ? Asymmetry from ~20mins DAQ data Constant with E from 1.3GeV – 1.9GeV

Axial channeling Very small angle Electron sees a string of charge Becomes trapped in potential and radiates may low energy photons Axial quasi channeling: an investigation D. Glazier, R.Owens, Glasgow Axial quasi channeling Small angle, but larger than for axial channeling Electron sees a string of charge Not fully trapped – produces photons with well defined polarisation at range of energies ? Some hints in 2D distributions from previous work, but no energy information. Requirements Tagged photon beam + high resolution 2D photon detector

A prototype photon beam profile detector D. Glazier, K.Livingston, Glasgow 1mrad Detector in MAMI beamlineProfile of MAMI photon beam

Measurements with photon beam profile detector D. Glazier, Glasgow 1 st Measurement of 2D photon enhancement for coherent bremsstrahlung (MAMI,Mainz) paper in preparation Good agreement with coherent bremstrahlung calculations Improvements in incoherent component, collimation + multiple scattering. No evidence of high energy photons from quasi channeling. Investigation of 2D strip detector for polarimetry Coherent peak at 300Mev, MAMI electron beam energy 855MeV below peakcoherent peakabove peak

Eurotag status ManpowerAll EU funded posts are now filled: 7 postdocs for > 11 man years Timelines On target ( averaged over 6 sub-projects )‏ Photon Tagging Develop prototype focal plane modules Complete used Glasgow Tagger Linearly Polarised Photons Develop prototype photon beam profile detector for quazi-channeling Complete – paper + report pending Develop linearly polarised photon beam at MAXLab, Lund. To be completed this year with upgraded beam Develop software toolkit for polarised photon beams. Complete. Tools available and in use at several labs. Develop “proof of principle polarimeter” for linearly polarised photons. Simualtion complete. To be built over next year. Develop polarimetry for double polarisation experiments. Preliminary analysis of CB data underway. Awaiting polarised target.

16 EuroPol: Polarisation Observables in Hadron Physics Topics: Complete pseudo-scaler meson measurements Electron & photon beam polarimetry & detector development Nucleon polarimetry for nucleon time-like form factors Recoil-nucleon polarimeters for photoproduction experiments Double polarisation measurements of nucleon space-like form factors Polarised 3He neutron targets Deuteron polarimetry to access electric dipole moment components A coherent framework for modelling hadronic interactions in matter Applications of hadronic-interaction models Facilities: DAFNE, LNF Frascati ELSA, Bonn MAMI-C, Mainz MAX-lab, Lund TJNAF, Newport News Spokesperson & Contact J.R.M. Annand (Glasgow)‏ Participants: Bonn, Germany Edinburgh, UK Frascati, Italy Giessen, Germany Glasgow, UK Lund Sweden Mainz, Germany Pavia, Italy Torino, Italy Dubna, Russia Jefferson Lab., USA Kharkov, Ukraine Yerevan, Armenia EM-probe studies of hadronic structure & physics beyond SM: pol. beams, targets,hadron polarimeters Objectives: Identify polarisation-observable combinations suited to particular hadronic- structure puzzles. Design & test experimental techniques Develop computational models Explore applications in dosimetry & industry