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Title: Study of luminosity leveling with crossing angle for polarized proton program at RHIC

Abstract

Luminosity leveling has been requested by experiments in the past and it is also foreseen in the future at RHIC. There are some options to do this, some well tested and some are potential. In this report, we present the theoretical and experimental study on leveling luminosity by crossing angle.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). Relativistic Heavy Ion Collider (RHIC)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1344228
Report Number(s):
BNL-113507-2017-IR
R&D Project: KBCH139; KB0202011
DOE Contract Number:
SC00112704
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Relativistic Heavy Ion Collider

Citation Formats

Liu, C., Blackler, I., Luo, Y., Marusic, A., Minty, M., Ranjbar, V., and Robert-Demolaize, G. Study of luminosity leveling with crossing angle for polarized proton program at RHIC. United States: N. p., 2017. Web. doi:10.2172/1344228.
Liu, C., Blackler, I., Luo, Y., Marusic, A., Minty, M., Ranjbar, V., & Robert-Demolaize, G. Study of luminosity leveling with crossing angle for polarized proton program at RHIC. United States. doi:10.2172/1344228.
Liu, C., Blackler, I., Luo, Y., Marusic, A., Minty, M., Ranjbar, V., and Robert-Demolaize, G. Wed . "Study of luminosity leveling with crossing angle for polarized proton program at RHIC". United States. doi:10.2172/1344228. https://www.osti.gov/servlets/purl/1344228.
@article{osti_1344228,
title = {Study of luminosity leveling with crossing angle for polarized proton program at RHIC},
author = {Liu, C. and Blackler, I. and Luo, Y. and Marusic, A. and Minty, M. and Ranjbar, V. and Robert-Demolaize, G.},
abstractNote = {Luminosity leveling has been requested by experiments in the past and it is also foreseen in the future at RHIC. There are some options to do this, some well tested and some are potential. In this report, we present the theoretical and experimental study on leveling luminosity by crossing angle.},
doi = {10.2172/1344228},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 25 00:00:00 EST 2017},
month = {Wed Jan 25 00:00:00 EST 2017}
}

Technical Report:

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  • A big problem in RHIC 100 GeV proton run 2009 was the significantly lower luminosity lifetime than all previous runs. It is shown in this note that the beam intensity decay in run 2009 is caused by the RF voltage ramping in store. It is also shown that the beam decay is not clearly related to the beam momentum spread, therefore, not directly due to the 0.7m. β* Furthermore, the most important factor regarding the low luminosity lifetime is the faster transverse emittance growth in store, which is also much worse than the previous runs, and is also related tomore » the RF ramping. In 100 GeV proton run 2012a, the RF ramping was abandoned, but the β* was increased to 0.85m, with more than 20% loss of luminosity, which is not necessary. It is strongly suggested to use smaller β* in 100 GeV polarized proton run 2015/2016« less
  • .
  • The effective bandwidth of the CDF-II level 1 trigger is approximately 25 kHz. Some of this bandwidth is used to record events that form the data sets used by the high p{sub T} physics analyses. The remaining bandwidth is used by triggers that are sensitive to hadronic B decays and provide one of the most important samples used for the study of B{sub s}{sup 0} mixing. At high luminosities, the hadronic B triggers have rates that greatly exceed the available bandwidth. Rather than incur large dead-times associated with these excessive rates, these B triggers are prescaled to limit the totalmore » trigger rate to the effective level 1 trigger bandwidth. The prescales are dynamically adjusted as the store progresses so that all of the bandwidth that is not used for the high p{sub T} physics program is used to record hadronic B triggers. In principle, the luminosity could be held at a more constant level throughout the store in such a way that the integrated luminosity would be the same as that obtained from a normal store. It has been suggested that this would allow B triggers to be recorded with lower prescales and consequently with higher B{sub s}{sup 0} signal efficiencies. This note describes a parametric model of the high p{sub T} and hadronic B triggers used by CDF and compares the yields of reconstructed B{sub s}{sup 0} decays that would result with and without luminosity leveling.« less