A proposal for a polarized 3 He ++ ion source with the EBIS ionizer for RHIC. A.Zelenski, J,Alessi, E.Beebe, A.Pikin BNL M.Farkhondeh, W.Franklin, A. Kocoloski, R.Milner, C. Tschalaer, E.Tsentalovich MIT-Bates E.Hughes Caltech SPIN 2004, Trieste. Motivation.
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A proposal for a polarized 3He++ ion source with the EBIS ionizer for RHIC.
A.Zelenski, J,Alessi, E.Beebe, A.PikinBNL
M.Farkhondeh, W.Franklin, A. Kocoloski, R.Milner, C. Tschalaer, E.TsentalovichMIT-Bates
SPIN 2004, Trieste
No new operational 3He ion sources were built.A number of new ideas were proposed and tested (not successfully).
Spin-exchange and “metastability-exchange” techniques for 3He atoms polarization were greatly improved due to laser development and demanding applications.
State of the art performance from
Mainz group using new fiber lasers
50 bar liters/day = 1.3 x 1020 atoms/sec
The source was operated at Texas A&M cyclotron during the 1976-78.
Monte-Carlo simulations for 3He++ polarization in ECR ionizer. Excitation cross-section is an order of magnitude larger than ionization to He++. There will be a polarization loss in excited states in <10 kG field ECR source. Polarization 10-20%.
ECR-ionizer for the 3He++ ions. RCNP, Osaka.
He-3 metastability-exchange polarized cell.
B~ 50 kG
Pumping laser 1083 nm.
~50·1011 , 3He/pulse. P=70-80%.
100 mA of a 1.0 keV energy He+ ion beam
at 1083 nm
~3 kG field
3He +D p + 4He + 18.35 MeV.
3He++/pulse with nuclear polarization: P >70 %.
This source was operated at the cyclotron in 1970-80 s .
P ~ 70-80%
Cross-section: σ (4He++ +3He →4He + 3He++) = 4·10-16 cm2 at 50 eV beam energy.
Estimated current 100 uA polarized 3He++.
Rb: NL(Rb) ~1014 cm-2
Stripper at 150kev,
1.5 kG field
Supperconducting solenoid 25 кГс
Spin-exchange collisions:~0.6·10-14 cm2
Electron to proton polarization transfer
Laser beam is a primary source of angular momentum:
10 W (795 nm) 4•1019 h/sec
Spin-exchange cross-sections lower than expected?
Higher Rb thickness is required (~1015 at./cm2) to obtain high polarization.
Very high Rb thickness is required!