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Title: RHIC Polarized proton operation

Abstract

The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the storemore » to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above injection, the polarized hydrogen jet target runs for every fill with both beams. Based on the known analyzing power, there is very little polarization loss between injection and 100 GeV. An alternative way is to measure the asymmetry at 100 GeV followed by ramping up to 250 GeV and back down to 100 GeV and then to measure the asymmetry again at 100 GeV. If the asymmetry after the down ramp is similar to the measurement before the up ramp, polarization was also preserved during the ramp to 250 GeV. The analyzing power at storage energy can then be extracted from the asymmetries measured at 100 GeV and 250 GeV. The tune and orbit feedbacks are essential for the down ramp to be possible. The polarized proton operation is still going on. We will push bunch intensity higher until reaching the beam-beam limit. The even higher intensity will have to wait for the electron lenses to compensate the beam-beam effect. To understand the details of spin dynamics in RHIC with two snakes, spin simulation with the real magnet fields have been developed recently. The study will provide guidance for possible polarization loss schemes. Further polarization gain will requires a polarized source upgrade; more careful setup jump quads in the AGS to get full benefit; and control emittance in the whole accelerator chain.« less

Authors:
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Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). Relativistic Heavy Ion Collider (RHIC)
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1016666
Report Number(s):
BNL-94193-2011-CP
R&D Project: KBCH139; 18031; KB0202011; TRN: US1103109
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Conference
Resource Relation:
Conference: 2011 Particle Accelerator Conference (PAC'11); New York, NY; 20110328 through 20110401
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 43 PARTICLE ACCELERATORS; ACCELERATORS; ASYMMETRY; BEAM DUMPS; BETATRONS; ELECTRONS; HEAVY IONS; HYDROGEN; LUMINOSITY; MAGNETS; MODIFICATIONS; POLARIMETERS; POLARIZATION; POLARIZATION-ASYMMETRY RATIO; POLARIZED BEAMS; PROTONS; RESONANCE; RF SYSTEMS; SPIN; STORAGE; TARGETS; relativistic heavy ion collider

Citation Formats

Huang, H, Ahrens, L, Alekseev, I G, Aschenauer, E, Atoian, G, Bai, M, Bazilevsky, A, Blaskiewicz, M, Brennan, J M, Brown, K A, Bruno, D, Connolly, R, Dion, A, D'Ottavio, T, Drees, K A, Fischer, W, Gardner, C, Glenn, J W, Gu, X, Harvey, M, Hayes, T, Hoff, L, Hulsart, R L, Laster, J, Liu, C, Luo, Y, MacKay, W W, Makdisi, Y, Marr, G J, Marusic, A, Meot, F, Mernick, K, Michnoff, R, Minty, M, Montag, C, Morris, J, Nemesure, S, Poblaguev, A, Ptitsyn, V, Ranjibar, V, Robert-Demolaize, G, Roser, T, J,, Severino, F, Schmidke, B, Schoefer, V, Severino, F, Smirnov, D, Smith, K, Steski, D, Svirida, D, Tepikian, S, Trbojevic, D, Tsoupas, N, Tuozzolo, J. Wang, G., Wilinski, M, Yip, K, Zaltsman, A, Zelenski, A, Zeno, K, and Zhang, S Y. RHIC Polarized proton operation. United States: N. p., 2011. Web.
Huang, H, Ahrens, L, Alekseev, I G, Aschenauer, E, Atoian, G, Bai, M, Bazilevsky, A, Blaskiewicz, M, Brennan, J M, Brown, K A, Bruno, D, Connolly, R, Dion, A, D'Ottavio, T, Drees, K A, Fischer, W, Gardner, C, Glenn, J W, Gu, X, Harvey, M, Hayes, T, Hoff, L, Hulsart, R L, Laster, J, Liu, C, Luo, Y, MacKay, W W, Makdisi, Y, Marr, G J, Marusic, A, Meot, F, Mernick, K, Michnoff, R, Minty, M, Montag, C, Morris, J, Nemesure, S, Poblaguev, A, Ptitsyn, V, Ranjibar, V, Robert-Demolaize, G, Roser, T, J,, Severino, F, Schmidke, B, Schoefer, V, Severino, F, Smirnov, D, Smith, K, Steski, D, Svirida, D, Tepikian, S, Trbojevic, D, Tsoupas, N, Tuozzolo, J. Wang, G., Wilinski, M, Yip, K, Zaltsman, A, Zelenski, A, Zeno, K, & Zhang, S Y. RHIC Polarized proton operation. United States.
Huang, H, Ahrens, L, Alekseev, I G, Aschenauer, E, Atoian, G, Bai, M, Bazilevsky, A, Blaskiewicz, M, Brennan, J M, Brown, K A, Bruno, D, Connolly, R, Dion, A, D'Ottavio, T, Drees, K A, Fischer, W, Gardner, C, Glenn, J W, Gu, X, Harvey, M, Hayes, T, Hoff, L, Hulsart, R L, Laster, J, Liu, C, Luo, Y, MacKay, W W, Makdisi, Y, Marr, G J, Marusic, A, Meot, F, Mernick, K, Michnoff, R, Minty, M, Montag, C, Morris, J, Nemesure, S, Poblaguev, A, Ptitsyn, V, Ranjibar, V, Robert-Demolaize, G, Roser, T, J,, Severino, F, Schmidke, B, Schoefer, V, Severino, F, Smirnov, D, Smith, K, Steski, D, Svirida, D, Tepikian, S, Trbojevic, D, Tsoupas, N, Tuozzolo, J. Wang, G., Wilinski, M, Yip, K, Zaltsman, A, Zelenski, A, Zeno, K, and Zhang, S Y. 2011. "RHIC Polarized proton operation". United States. https://www.osti.gov/servlets/purl/1016666.
@article{osti_1016666,
title = {RHIC Polarized proton operation},
author = {Huang, H and Ahrens, L and Alekseev, I G and Aschenauer, E and Atoian, G and Bai, M and Bazilevsky, A and Blaskiewicz, M and Brennan, J M and Brown, K A and Bruno, D and Connolly, R and Dion, A and D'Ottavio, T and Drees, K A and Fischer, W and Gardner, C and Glenn, J W and Gu, X and Harvey, M and Hayes, T and Hoff, L and Hulsart, R L and Laster, J and Liu, C and Luo, Y and MacKay, W W and Makdisi, Y and Marr, G J and Marusic, A and Meot, F and Mernick, K and Michnoff, R and Minty, M and Montag, C and Morris, J and Nemesure, S and Poblaguev, A and Ptitsyn, V and Ranjibar, V and Robert-Demolaize, G and Roser, T and J, and Severino, F and Schmidke, B and Schoefer, V and Severino, F and Smirnov, D and Smith, K and Steski, D and Svirida, D and Tepikian, S and Trbojevic, D and Tsoupas, N and Tuozzolo, J. Wang, G. and Wilinski, M and Yip, K and Zaltsman, A and Zelenski, A and Zeno, K and Zhang, S Y},
abstractNote = {The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above injection, the polarized hydrogen jet target runs for every fill with both beams. Based on the known analyzing power, there is very little polarization loss between injection and 100 GeV. An alternative way is to measure the asymmetry at 100 GeV followed by ramping up to 250 GeV and back down to 100 GeV and then to measure the asymmetry again at 100 GeV. If the asymmetry after the down ramp is similar to the measurement before the up ramp, polarization was also preserved during the ramp to 250 GeV. The analyzing power at storage energy can then be extracted from the asymmetries measured at 100 GeV and 250 GeV. The tune and orbit feedbacks are essential for the down ramp to be possible. The polarized proton operation is still going on. We will push bunch intensity higher until reaching the beam-beam limit. The even higher intensity will have to wait for the electron lenses to compensate the beam-beam effect. To understand the details of spin dynamics in RHIC with two snakes, spin simulation with the real magnet fields have been developed recently. The study will provide guidance for possible polarization loss schemes. Further polarization gain will requires a polarized source upgrade; more careful setup jump quads in the AGS to get full benefit; and control emittance in the whole accelerator chain.},
doi = {},
url = {https://www.osti.gov/biblio/1016666}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 28 00:00:00 EDT 2011},
month = {Mon Mar 28 00:00:00 EDT 2011}
}

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