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OPPIS performances in Run-6.
First 4 weeks.
RSC meeting, February 10, 2006
A new semiconductor probe laser for Faraday
rotation polarimeter.
A new semiconductor probe laser for Faraday
rotation polarimeter.
40 kW Ar-ion laser“Toptica” laser
150 mW at 780 nm
300 W power supply.
Polarized H- ion current pulse out of 200 MeV linac.
Polarized H- ion current pulse out of 200 MeV linac.
Faradey rotation polarization sinal.
500 uA cuurentAt 200 MeV.85-hole ECRSource for themaximum polarization.
400 uS 12·1011 -polarized H- /pulse.
Rb-vapor thickness
measurement by
Faraday rotation
technique.
SONA-TRANSITION.
Sona-transition
ECR-zone
Polarization transfer from electrons to protons .
Correction coil
Magnetic field gradient in the Sona-region.
Longitudinal Bz field in the Sona region at different correction coil current settings.
Correction coil scan.Correction coil scan.
60
65
70
75
80
85
90
3.5 4 4.5 5 5.5 6 6.5
Correction coil current
Pola
rizat
ion
,%
Ionizer coil current – 220 A
A new (short 230 mm) optically-pumped Rb-vapor cell assembly.
A new (short 230 mm) optically-pumped Rb-vapor cell assembly.
A new vacuum chamber.
A new cooling system.
A new water cooled deflecting plates.
Proton polarization vs Rb vapor thickness.Proton polarization vs Rb vapor thickness.
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7
Rb vapor thickness, 1013 atoms/cm2
Prot
on p
olar
izat
ion,
%
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25
Rb vapor thickness, 1013 atoms/cm2
Prot
on p
olar
izat
ion,
%
Long Rb cell
A new short Rb cell
200 MeV polarization measurements (raw).
121 hole ECR
Probe laserFailure.
55 hole ECR
Jan16 Febr.6
A new APD detectors at 200 MeV polarimeter.
Signals from Avalanche Photo Diodes from LED and Ru-106 beta-source.
Upgrade status.Upgrade status.
• A new semiconductor laser for the Faraday rotation polarimeter was installed, aligned and tuned. This reduced total souce power consumption from 65 kW to 15 kW.
• The cause of laser diode failures was identified and fixed.
• A new Rb-cell assembly was built and tested. It should improve the polarization (slightly). The old Rb-cell will be a spare.
• There are still considerable polarization losses at the Sona-transition.
• The ECR source upgrades improved the reproducibility and reliable long term operation at high bem intensity.
• A new APD-based proton detectors for 200 MeV polarimeter were built and tested.
Conclusions.Conclusions.
• BNL OPPIS reliably delivered polarized H- ion beam (P= 80-82%) in the 2005 run for the RHIC spin program.
• A beam intensity exceeds RHIC limit, which allowed strong beam collimation in the Booster, to reduce longitudinal and transverse beam emittances.
• In the 2006 run we will try to revitalize the p-D polarimeter for the absolute polarization value measurements
• After upgrade the OPPIS provides sufficient intensity and higher polarization for the Spin 2006 run in RHIC.
