9 th Crystal Ball Meeting Basel October Andreas Thomas Transversely Polarized Target 1.-Possible Physics Experiments 2.-Frozen Spin Target 3.-Technical Realization of a transverse magnet

4 complex amplitudes – 16 observables in meson photoproduction Each double polarisation observable gives different combination of amplitudes To fix the 4 amplitudes unambiguously → 8 real quantities Cannot choose from the same set Complete Experiment

Beam Target Photoproduction with polarized beam and polarized target

Real compton scattering with polarized beam and polarized target         Dispersion relation theory  PT lattice QCD..?

Polarized target „Frozen Spin Mode“  Polarization : DNP at high B-Field (2.5 T)  Measurement : very low T ´freeze´ up the spin (0.4 Tesla) relaxation time h  200   (T,B,Mat.,Rad.,.....)

Free electrons Radicals in material by chemical or radiative doping Butanol Ammonia LiD 30mm N H H H N O CH 3 Tempo Radical density influences Max. Pol. Pol. Buildup Relaxation time

Beam heating 1. CW-Beam: ELSA, MAMI, JLAB, Pulsed beam: SLAC, Fourier equation Assumption: target beads have spherical symmetry

Beam heating Target material is stored in a PTFE-container and cooled by liquid 3/4helium mixture at 0.05Kelvin T r Thermal conductivity Kapitza resistance  T2T2 T1T1 T bath Input : minimum ionizing particle e- 60% deposition measured with flowmeter acoustic mismatch R=1mm

Beam heating Time dependencePulsed beam [T.J.Liu et al., NIM A405(1998)1-12]SLAC E143 Beam size 1.4mm diameterBeam rastering necessary Short pulse 2.3  sec Long break 2 secRepolarizing the bead

Butanol (C 4 H 9 OH) Bonn GDH Coil Mainz Coil under prepar. 30A ~ 0.6 T (200  m NbTi) Cooled by Evaporator horizontal cryostat with integrated solenoid (holding field): Bonn Kelvin 0.42 Tesla equiv. 780  m Cu (100  m NbTi)

· Current leads (30A):Copper T=300K  70 K Tc SC T= 70K  4 K NiTi T= 4K  1.5K

Technical Realisation of a Transverse Magnet [E.Dzyubak et al., NIM A 526 (2004) , OPERA3D calculations]

Epoxy Impregnated, Elasticity  Vibration  Quench? [talk Ch. Keith EU-Workshop Rech 2005]

Conclusions and outlook 1.-Longitudinal holding Magnet- first test fall of this year with new cryo - Magnet. Field and current lead design ??? - 2nd coil in Mainz workshop (+4 weeks) 2.-Transverse magnet- some money in 2007 from SFB available - manpower (diploma thesis…) needed for calculations and tests - investigation of possibility of commercial production

Real compton scattering with polarized beam and polarized target Circularly polarized beam Linearly polarized beam Target polarized longitudinally Target polarized transverse Dispersion relation,  PT, lattice QCD..?        