Comments on the operation of the RHIC CNI polarimeters.

[摘要] The RHIC polarimeter data have exhibited behavior suggesting that systematic effects are present at a level comparable to the statistical uncertainty per run, or {approx} 4 x 10{sup 4}: in the physics asymmetries and somewhat larger in the luminosity asymmetries. This corresponds to an error in the polarization of approximately {delta}P {approx} {+-} 0.03. Two effects are studied that might explain some of the observations, both based on detector rates. The results may explain the systematic effects in both the physics and the luminosity asymmetries. The first effect is caused by the presence of both a background and a good p + C elastic scattering event in the same passage of a bunch through the polarimeter target. The second effect similarly depends on the presence of multiple p + C elastic events from the same bunch. If these rate effects become large enough (or if {delta}P {approx} {+-} 0.03 continues and the beam polarization is less than 0.60) they could prevent determination of the beam polarization to {delta}P/P = {+-} 5% unless a correction can be determined to the measured asymmetries.

[发布日期] 2003-12-18 [发布机构] Argonne National Laboratory

[关键词] Asymmetry;43 Particle Accelerators;Elastic Scattering;Beam Bunching;Beam Luminosity