Emittance measurements using Vernier Scans during Run 09 (pp at 250 GeV)

Drees, A.

Brookhaven National Laboratory. Collider-Accelerator Department.

关键词: Beam Position;    43 Particle Accelerators;    Relativistic Heavy Ion Collider;    Beam Profiles;    Protons Relativistic Heavy Ion Collider;   

DOI  :  10.2172/1000450
RP-ID  :  BNL--94373-2010-IR
RP-ID  :  DE-AC02-98CH10886
RP-ID  :  1000450

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来源: UNT Digital Library

【 摘 要 】

Emittance measurements using the vernier scan technique give reliable results for 250 GeV protons even though the transverse beam profiles have non-Gaussian tails. Those non-Gaussian tails were observed for the first time this run at the 250 GeV beam energy. The vernier scan measurements are in excellent agreement with the emittances derived from collision rates and show practically no fill to fill scatter if compared to the latter. The results are consistent with a {beta}* of 0.7 m and round beams. The IPM measurements show a discrepancy of up to 80% compared with the vernier scan data and a fill to fill scatter of up to 30%. If an uncertainty in the beta-function at the location of the IPM is the root cause, this uncertainty seems to be quite large. In any case, such an uncertainty could not explain the fill to fill variations of up to 30% which indicate yet another underlying reason that could explain fill to fill variations (candidates could be beam intensity issues with the IPM, beam position at the IPM, varying background etc.).