17th Crystal Ball Meeting
-
Upload
blaise-riley -
Category
Documents
-
view
222 -
download
0
description
Transcript of 17th Crystal Ball Meeting
17th Crystal Ball Meeting
Institut fr Kernphysik Frozen Spin Target 1.- Polarised Target
Operation 2.- Short Term Plans 3.- Modifications 4.- Long term
plans 17th Crystal Ball Meeting Mainz, February 28th, 2011 Andreas
Thomas Operation Cryostat Movable Crystal Ball 4p- Photon Detector
Movable
5Tesla Polarising Magnet First Beam with Transverse Polarisation
started 15th December 2009. In 2010 we had more than 2000 hours
beam on this target. Cryostat Performance T=24mK T=27mK T=29mK
Dt=40h
Temperature stability: DT ~ mKelvin (one day) (typical one week
measurement period). Frozen Spin Target Relaxationtime
26 mK, 0.44T Relaxation time of butanol at 60 mK depending on the
applied magnetic field Target material Dilution factor
(fButanol=10/74)
Free electrons Radicals in material by chemical or radiative doping
Saturated electrons of target material not polarized (Pauli
principle) Dilution factor (fButanol=10/74) determines quality of
target material. We have9*1022 pol. Protonsper cm2 in our 2cm long
target cell. 2cm Butanol N O CH3 Tempo Filling factor ~ 60% H.
Ortega Spina
C4H10O 60% 30mm Filling factor ~ 60% H. Ortega Spina 3He/4He 6%
Vacuum Degree of Polarisation
Soldering of the NMR coil (target material has to be kept under
liq. Nitrogen) and installation into the cryostat. X-ray picture
with Beamspot and NMR coil from last week. NMR System for
Polarisation measurement
B=0T B=2.5T Typical NMR Signals Enhanced Signal at 70%
Polarisation
after spin rotation Thermal Equilibrium-Signal 0.5% Polarisation
2.5Tesla,1Kelvin Temperature measurement
AVS Picowatt Resistance Bridge ! Systematic error for all
asymmetries! Highest Deuteron polarisation due to new
Target material Density and species of the radicals are very
important for: maximum degree of polarization polarization build up
times relaxation times Trityl-Radikal D-Butanol [Gerhard Reicherz,
PT Ruhr-Universitt Bochum, Next talk] Highest Deuteron polarisation
due to new doping material with narrow ESR from Bochum. Deuteron
NMR Signals Short term plans Proposal:
Beam for 3 weeks in April (proton target optimized for ph and h)
Beam for 2 weeks in May (deuteron target broad band at 1557MeV)
Dismounting Cryostat after final test (TE-calibration, filling
factor) Mounting of EPTagger. Mounting of liquid hydrogen target
(cell length 3cm or 5cm or 10cm?). Test beamtime end of
summer/fall. Modifications: Magnet Technology
DNP at 200mK and 2.5T with 70GHz microwaves. Frozen spin
target(25mKelvin, 0.6T). Secondary particles punch through holding
coil. All directions of polarization. Transverse (Saddle coil) and
Longitudinal (Solenoid) Internal Holding Field (1.2K, 0.6T) High
Field 1T Threshold Production Transverse Field Modifications:
Internal Polarising Coil
Problem is the requiredfield homogeniety of 10-E4. Notched
solenoid. 3d finite element calculation, optimisation and precise
production needed. DNP at 200mK and 2.5T with 70GHz microwaves.
10Layer coil at 50A. Secondary particles punch through holding
coil. Higher momentum threshold. New Coil with 10 layer (2.5Tesla)
in
Mainz mechanical workshop. Modifications: Active Polarised
Target
Talk S.Schrauf 3He/4He 6% Vacuum Long term plans Change from
transverse to longitudinal polarisation.
Internal polarising coil for high luminosity and precission
experiments. Active polarised target for treshhold experiments.