JRA3 Eurotag report, Oct 2006 1

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:

Manpower All EU funded posts are now filled: 7 postdocs for > 11 man years

Workshop A 2 day workshop to be held early 2007.

Timelines On target ( averaged over 6 sub-projects )

Dissemination Web site: www.nuclear.gla.ac.uk/~kl/Eurotag …. needs updating.

Internal reports, conference proceedings

JRA3 Eurotag report, Oct 2006 2

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 2006

400 boards made by Zott. Currently being installed

Upgraded Glasgow Tagger in Mainz

JRA3 Eurotag report, Oct 2006 3

Polarimetry

1. Coherent Bremsstrahlung Calculation (Tuebingen)

Used successfully, needs only photon tagger

Many free parameters, > 5% systematic error

Developments by Glasgow and Tuebingen

Papers in preparation (D.Glazier, P. Grabmayr)

2. Use reaction with a known photon asymmetry (Mainz)

Can be high statistics

Very good relative monitor of polarization

Non-indpendent – depends on specific expt

Need very good systematics or calibration

Investigation by Mainz (R. Beck et al.)

JRA3 Eurotag report, Oct 2006 4

3. Build a prototype polarimeter (Bonn, Kharkov, Glasgow, Jlab)

Kharkov Monte carlo simulations of Pair and Triplet polarimetry solutions (with Bonn)

Jlab Recent 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

Polarimetry