Presentation on theme: "Polarized 3He ++ ion source development for RHIC. Check the Bjorken Spin Sum Rule (the difference between the 1st moments of the proton and neutron spin."— Presentation transcript:
Polarized 3He ++ ion source development for RHIC. Check the Bjorken Spin Sum Rule (the difference between the 1st moments of the proton and neutron spin structure function). Violation of that would be a very big deal. If we find the rule to be CONFIRMED, i.e. no violations, then these evaluation will give the BEST value of the strong coupling constant Alpha-S and its running. A.Deshpande Polarized 3He ++ ions can be accelerated in RHIC with the present “siberian snakes”. Electron Beam Ion Source is being constructed at CAD. A.Zelenski. J.Alessi, E.Beebe, A.Pikin, A.Kponou, D.Steski
EBIS ionizer for polarized 3 He gas. He(2S)→ He(1S) He(2S)→ He(1S) He-3 metastability -exchange polarized cell P - 80-90%. Pumping laser 1083 nm. EBIS-ionizer, B~ 50 kG EBIS-ionizer, B~ 50 kG RFQ He-transfer line. Valve. ~50·10 11, 3 He /pulse. 2.5·10 11 He ++ /pulse
EBIS ionizer for polarized 3 He gas. Polarized 3 He gas is produced by a “metastability exchange” technique. P ~ 70-80% (pressure ~ 1 torr). 3 He gas is injected in the EBIS ionizer. Pulsed valve? The ionization in EBIS is produced in a 50 kG field. This field will greatly suppress the depolarization in the intermediate He + single charge state, B c (He + ) = 3.1 kG The charge ratio He ++ /He + >> 1. The number of He ++ ions is limited to maximum charge which can be confined in EBIS (about 2.5 ·10 11 of 3 He ++ /store). It is sufficient to obtain ~10 11 He ++ /bunch in RHIC.
Electron Beam Ion Source at RHIC E-Gun (10 A) Drift Tube Structure Electron Collector Superconducting Solenoid (6 T) Acceleration Tube What intensity is expected? Capacity will be 10 12 charges/pulse ~ 2-3 x 10 11 3 He ++ ions per pulse ?
EBIS Preinjector Layout in lower equipment bay of 200 MeV Linac Beam port Booster Linac RFQ EBIS 17 keV/u 300 keV/u 2 MeV/u 100 MHz Ion He - U Q/m≥1/6 Current> 1.5 emA (for 1 turn inj) Pulse Length 10 s Rep. Rate5 Hz Time to switch species1 second Polarimeter
SUMMARY Expected Results. Building of the He –3 polarizing setup. Study the limitation on the maximum attainable nuclear polarization in the metastability-exchange technique. Study the possible depolarization effects during polarized 3 He gas injection to EBIS and multi-step ionization process. 3He++ beam polarimeter development for polarization measurements and optimization. Requested budget: $545 k/ 3 years (2 years postdoc is included).