IBIC2014 - List of Authors (Tepikian, S.)

Paper	Title	Page
MOPF02	RHIC-Style IPMs in the Brookhaven AGS	39
	R. Connolly, W.C. Dawson, J.M. Fite, H. Huang, S.E. Jao, W. Meng, R.J. Michnoff, S. Tepikian BNL, Upton, Long Island, New York, USA
	Funding: Work supported by U.S. Department of Energy. Beam profiles in the two storage rings of the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Lab (BNL) are measured with ionization profile monitors (IPMs). An IPM measures the distribution of electrons produced by beam ionization of background gas. These detectors have been developed at BNL in a program that began in 1996. The current detectors are a design from 2009. During the 2012 shutdown we refurbished the 2009 prototype detector and installed it in the Alternating-Gradient Synchrotron (AGS) for horizontal profiles. The commissioning tests were successful and in 2013 we built a new IPM for vertical profiles. In addition we placed coils on the backlegs of the permanent-magnet dipoles for beta-function measurements. This paper describes the AGS IPMs and shows data from the detector commissioning.
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MOPF04	RHIC Injection Transport Beam Emittance Measurements	45
	J.Y. Huang Duke University, Durham, North Carolina, USA D.M. Gassner, M.G. Minty, S. Tepikian, P. Thieberger, N. Tsoupas, C.M. Zimmer BNL, Upton, Long Island, New York, USA
	The Alternating Gradient Synchrotron (AGS)-to-Relativistic Heavy Ion Collider (RHIC) transfer line, abbreviated AtR, is an integral component for the transfer of proton and heavy ion bunches from the AGS to RHIC. In this study, using 23.8 GeV proton beams, we focused on factors that may affect the accuracy of emittance measurements that provide information on the quality of the beam injected into RHIC. The method of emittance measurement uses fluorescent screens in the AtR. The factors that may affect the measurement are: background noise, calibration, resolution, and dispersive corrections. Ideal video Offset (black level, brightness) and Gain (contrast) settings were determined for consistent initial conditions in the Flag Profile Monitor (FPM) application. Using this information, we also updated spatial calibrations for the FPM using corresponding fiducial markings and sketches. Resolution error was determined using the Modulation Transfer Function amplitude. To measure the contribution of the beam’s dispersion, we conducted a scan of beam position and size at relevant Beam Position Monitors (BPMs) and Video Profile Monitors (VPMs, or “flags”) by varying the extraction energy with a scan of the RF frequency in the AGS. The combined effects of these factors resulted in slight variations in emittance values, with further analysis suggesting potential discrepancies in the current model of the beam line’s focusing properties. In the process of testing various contributing factors, a system of checks has been established for future studies, providing an efficient, standardized, and reproducible procedure that might encourage greater reliance on the transfer line’s emittance and beam parameter measurements.
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MOPF09	Absolute Beam Emittance Measurements at RHIC Using Ionization Profile Monitors	64
	M.G. Minty, R. Connolly, C. Liu, T. Summers, S. Tepikian BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy In this report we present studies of and measurements from the RHIC ionization profile monitors (IPMs). Improved accuracy in the emittance measurements has been achieved by (1) continual design enhancements over the years, (2) application of channel-by-channel offset corrections and gain calibrations in the beam profile measurements and (3) use of measured beta functions at the locations of the IPMs. The removal of systematic errors in the emittance measurements was confirmed by the convergence of all four planes of measurement (horizontal and vertical planes of both the Blue and Yellow beams) to a common value during beam operations with stochastic cooling. Consistency with independent measurements (luminosity-based using zero degree counters) at the colliding beam experiments STAR and PHENIX was demonstrated.
	Poster MOPF09 [1.109 MB]
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Paper

Title

Page

RHIC-Style IPMs in the Brookhaven AGS

39

R. Connolly, W.C. Dawson, J.M. Fite, H. Huang, S.E. Jao, W. Meng, R.J. Michnoff, S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. Department of Energy.
Beam profiles in the two storage rings of the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Lab (BNL) are measured with ionization profile monitors (IPMs). An IPM measures the distribution of electrons produced by beam ionization of background gas. These detectors have been developed at BNL in a program that began in 1996. The current detectors are a design from 2009. During the 2012 shutdown we refurbished the 2009 prototype detector and installed it in the Alternating-Gradient Synchrotron (AGS) for horizontal profiles. The commissioning tests were successful and in 2013 we built a new IPM for vertical profiles. In addition we placed coils on the backlegs of the permanent-magnet dipoles for beta-function measurements. This paper describes the AGS IPMs and shows data from the detector commissioning.

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MOPF04

RHIC Injection Transport Beam Emittance Measurements

45

J.Y. Huang
Duke University, Durham, North Carolina, USA
D.M. Gassner, M.G. Minty, S. Tepikian, P. Thieberger, N. Tsoupas, C.M. Zimmer
BNL, Upton, Long Island, New York, USA

The Alternating Gradient Synchrotron (AGS)-to-Relativistic Heavy Ion Collider (RHIC) transfer line, abbreviated AtR, is an integral component for the transfer of proton and heavy ion bunches from the AGS to RHIC. In this study, using 23.8 GeV proton beams, we focused on factors that may affect the accuracy of emittance measurements that provide information on the quality of the beam injected into RHIC. The method of emittance measurement uses fluorescent screens in the AtR. The factors that may affect the measurement are: background noise, calibration, resolution, and dispersive corrections. Ideal video Offset (black level, brightness) and Gain (contrast) settings were determined for consistent initial conditions in the Flag Profile Monitor (FPM) application. Using this information, we also updated spatial calibrations for the FPM using corresponding fiducial markings and sketches. Resolution error was determined using the Modulation Transfer Function amplitude. To measure the contribution of the beam’s dispersion, we conducted a scan of beam position and size at relevant Beam Position Monitors (BPMs) and Video Profile Monitors (VPMs, or “flags”) by varying the extraction energy with a scan of the RF frequency in the AGS. The combined effects of these factors resulted in slight variations in emittance values, with further analysis suggesting potential discrepancies in the current model of the beam line’s focusing properties. In the process of testing various contributing factors, a system of checks has been established for future studies, providing an efficient, standardized, and reproducible procedure that might encourage greater reliance on the transfer line’s emittance and beam parameter measurements.

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MOPF09

Absolute Beam Emittance Measurements at RHIC Using Ionization Profile Monitors

64

M.G. Minty, R. Connolly, C. Liu, T. Summers, S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
In this report we present studies of and measurements from the RHIC ionization profile monitors (IPMs). Improved accuracy in the emittance measurements has been achieved by (1) continual design enhancements over the years, (2) application of channel-by-channel offset corrections and gain calibrations in the beam profile measurements and (3) use of measured beta functions at the locations of the IPMs. The removal of systematic errors in the emittance measurements was confirmed by the convergence of all four planes of measurement (horizontal and vertical planes of both the Blue and Yellow beams) to a common value during beam operations with stochastic cooling. Consistency with independent measurements (luminosity-based using zero degree counters) at the colliding beam experiments STAR and PHENIX was demonstrated.

Poster MOPF09 [1.109 MB]

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