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Discussion: Open questions and possible solutions for 3He Polarimetry. Online Polarimeter display. Carbon rate 50 - 100 kHz/ strip Prompts background to signal ~ 1/1 with an energy threshold cut at 125 keV. Shaper pulse rise time 20 nsec and fall time 50 nsec. Can we use 3He – Carbon CNI?
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Discussion: • Open questions and possible solutions for 3He • Polarimetry
Online Polarimeter display Carbon rate 50 - 100 kHz/ strip Prompts background to signal ~ 1/1 with an energy threshold cut at 125 keV. Shaper pulse rise time 20 nsec and fall time 50 nsec
Can we use 3He – Carbon CNI? Pro: We can do polarization profiles Use an existing system Con: Impact on the beam Will the helium breakup? The RHIC Carbon CNI polarimeters
Needed for setting up the spin rotators • The ZDCs measure a significant forward neutron asymmetry should we expect a similar analyzing power from Helium scattering? • Do we need to measure the spectator proton? • Roman Pots? • We need theoretical guidance The Local Polarimeters
The BBC polarimeters • Measure inclusive charged hadron production in the forward direction. A small analyzing power but with high rate. I suspect similar results from Helium scattering. • We need theoretical guidance • Should we think of some other schemes? The Local Polarimeters Cont’d
Need theoretical estimates of polarized 3He-3He scattering • Is a storage cell a viable option? • Where can it be located? A polarized Helium Jet
AGS • Do we need to measure beam polarization near injection? • The CNI targets do not allow this • Shall we employ a different process at low energy? • The CNI polarimeter is well poised for pol. 3He-Carbon measurements at AGS extraction energies Needed measurements
2. Obtain R directly from the P(I) fit: I P pC: Polarization Profile 1. Directly measure I and P : pC Scan the Carbon target over the beam: Intensity I Polarization P R=0.290.07 Target Position Precise target positioning is NOT necessary R ~ 0.1–0.3 5–15% difference in lower polarization seen by HJet compared to that observed by experiments