RHIC Polarized Proton Operations Mei Bai GSI Helmholtzzentrum

RHIC Polarized Proton Operations Mei Bai GSI Helmholtzzentrum für Schwerionenforschung

RHIC, THE WORLD’S 1 ST HIGH ENERGY PP COLLIDER https: //www. agsrhichome. bnl. gov/RHIC/Runs/

94 PRL

BRAHMS(p) Absolute Polarimeter (H jet) RHIC p. C Polarimeters Siberian Snakes PHENIX (p) STAR (p) Spin Rotators (longitudinal polarization) LINAC Pol. H Source 200 Me. V Polarimeter Spin Rotators (longitudinal polarization) BOOSTER AGS Helical Partial Siberian Snake AGS Polarimeters Strong AGS Snake 4 Spin. Fest, August 7, 2008

Snake Depolarization Resonance - Condition • S. Y. Lee, Tepikian, Phys. Rev. Lett. 56 (1986) 1635 • S. R. Mane, NIM in Phys. Res. A. 587 (2008) 188 -212 - even order resonance Disappears in the two snake case if the closed orbit is perfect - odd order resonance 3/4 Py current working point 11/16 7/10 old working point Driven by the intrinsic spin resonances

How to avoid a snake resonance? q Keep spin tune as close to 0. 5 as possible - Snake current setting - Minimize horizontal orbital angle between two snakes q Precise control of the vertical closed orbit q Precise optics control – – – Proper working point at a location with no or negligible snake resonances Minimize the linear coupling to avoid the resonance due to horizontal betatron oscillation Minimize spin tune spread

RHIC Polarization Performance pp@100 Ge. V pp@255 Ge. V pp@205 Ge. V pp@250 Ge. V • Commissioning of OPPIS, snakes, rotators • Operation modes developments • Improvement of injectors, beam controls and polarimeters

Milestones of RHIC pp Developement New polarized proton source (OPPIS) commissioned § One snake was installed in Blue ring and commissioned § CNI polarimeter in Blue installed and commissioned § 2000 2002 2003 All snakes for both rings installed and commissioned § CNI polarimeter in Yellow installed and commissioned § § RHIC absolute polarimeter using H Jet target installed and commissioned § AGS 5% helical warm snake installed and commissioned § RHIC polarized proton to 100 Ge. V engineering run § 2004 Spin rotators installed and commissioned

RHIC pp Engineering Run in 2004 A brief history of Run 04 Goal of the run June 7, 2004 RHIC Retreat 2004

Snake Current Scans • blue snakes and yellow snakes do behave differently • inner current: blue=323 A; yellow=321 A • outer current: blue=105 A; yellow=97 A • the snake current is very critical to get spin tune close to 1/2 • through out the run, the snake current was set to • inner current=(326 A, 321 A); outer current=(100 A, 100 A) June 7, 2004 RHIC Retreat 2004

RHIC New Working Point a snake depolarization resonance Loss rate Working point during ramp good spot for polarization as well as for beam lifetime good for Beam lifetime, but bad for polarization Courtesy of R. Tomas June 7, 2004 RHIC Retreat 2004

Tunes along the ramp Measured betatron tune Yellow tunes Blue tunes • No beam loss while crossing 7 th order resonance at 0. 717 • Other than the desired tune swing from (0. 72, 0. 73) to (0. 68, 0. 69), No significant tunes variations along the ramp flattop *=2 m *=1 m Time from the beginning of the ramp [s] June 7, 2004 RHIC Retreat 2004

Tune feed forward Before tune “ironing” after tune “ironing” June 7, 2004 RHIC Retreat 2004

Tune feedback June 7, 2004 RHIC Retreat 2004

Milestones of RHIC pp Developement RHIC absolute polarimeter using H Jet target installed and commissioned § AGS 5% helical warm snake installed and commissioned § RHIC polarized proton to 100 Ge. V engineering run § 2004 New super-conducting solenoid was installed in the OPPIS source § Polarized protons in RHIC to 205 Ge. V with ~ 30% polarization at top energy § AGS strong super-conducting helical snake installed and commissioned § 2005

Polarized proton collision at 205 Ge. V at RHIC

Milestones of RHIC pp Developement New super-conducting solenoid was installed in the OPPIS source § Polarized protons in RHIC to 205 Ge. V with ~ 30% polarization at top energy § AGS strong super-conducting helical snake installed and commissioned § 2005 commissioned the AGS dual snake configuration. AGS reaches a polarization of 65% at the AGS extraction with 1. 5 x 1011 protons per bunch § Polarized protons were accelerated to 250 Ge. V with a polarization of 45% § 2006 1 st Physics run of polarized protons at 250 Ge. V. discovered the strong snake resonance at 5 Qy=Qs+1 § polarization deteoration at a rate of ~1%/hour was observed at both 100 Ge. V as well as 250 Ge. V § 2009 first polarized proton run with full tune/coupling feedback. The improvement Long physics run of polarized protons at 255 Ge. V with vertical § 9 MHz cavity successfully commissioned § 2011

Polarization Performance: 250 Ge. V q Polarization loss between 100 Ge. V and 250 Ge. V - Measured with CNI polarimeter

7/10 resonance 11/16 resonance Setting for 2009 250 Ge. V run Setting for 2011 250 Ge. V run Snake resonance observed in RHIC 3/4 resonance

Milestones of RHIC pp Developement commissioned the AGS dual snake configuration. AGS reaches a polarization of 65% at the AGS extraction with 1. 5 x 1011 protons per bunch § Polarized protons were accelerated to 250 Ge. V with a polarization of 45% § 2006 polarized proton run at both 255 Ge. V and 100 Ge. V § AGS H tune jump technique was successfully commissioned and became operational § 9 MHz cavity became operational § 2012 polarized proton run at 255 Ge. V § Blue elens was installed and started its commissioning § OPPIS upgrade with fast atomic beam source and improved superconducting solenoid § longitudinal bunch-by-bunch damper was successfully commissioned § improved AGS H tune jump timing § 2013

Accelerating pp in the AGS with dual partial snakes Energy: 2. 3 Ge. V ~ 23. 8 Ge. V A total of 41 imperfection resonances and 7 intrinsic resonances from injection to extraction E 20 5. 9% A 20 10~15%

Spin tune with two partial snakes 36+Qy intrinsic resonance Spin tune Extraction Vertical component of stable spin Vertical betatron tune Courtesy of T. Roser Gg

Horizontal Resonance - Stable spin direction in the presence of two partial snakes is no long along vertical direction • vertical fields due to horizontal betatron oscillation can drive a resonance at G = k. P±Qx • Each is weak, and can be cured by tune jump • Tracking of 6 k particles in 6 -D Gaussian distribution(10π mm-mrad + 0. 8 ev-s) • Total CPU hour=10, 000 • done by Yann using zgoubi[1] Courtesy of Yann Dutheil

AGS Horizontal Tune Jump Quads • AGS horizontal tune jump quadrupoles to overcome a total of 80 weak horizontal spin resonances during the acceleration Qx e n i p S n tu 1 - Qx [1] V. Schoefer et al, INCREASINGTHEAGSBEAMPOLARIZATIONWITH 80 TUNEJUMPS, Proceedings of IPAC 2012, New Orleans, Louisiana, USA [2] F. Lin, et al. , Phys. Rev. ST 10, 044001 (2007) M. Bai IPAC’ 13, Shanghai, China, May 12 -May 17, 2013

Precise Beam Control • Tune/coupling feedback system: acceleration close to 2/3 orbital resonance • Orbit feedback system: rms orbit distortion less than 0. 1 mm

The Golden Store of RUN 13 Improved longitudinal matching at RHIC injection led smaller beam emittance. Together with improved 3 rd order resonance correction of store lattice improved polarization lifetime significantly

Summary • The success of RHIC polarized proton operation is the result of original scientific vision and excellent team work! – The original RHIC spin collaboration who initiated RHIC spin program – The strong support of the funding agencies, BNL, DOE, RIKEN, etc – The accelerator team who designed, constructed, commissioned the collider! – Fantastic coordination among accelerator folks and experimental folks • Donuts and cookies helped a bit deal! • The success of the RHIC spin program will soon lead us to the next excitement with Electron Ion Collider that can allow us to continue the passion for spin physics that Jacques Soffer and other spin physicists and further understand the glues that bind us together!

An Incredible Team L. Ahrens, E. C. Aschenauer, G. Atoian J. Beebe-Wang, M. Blaskiewicz J. M. Brennan, K. Brown, D. Bruno, R. Connolly, K. O. Eyser T. D’Ottavio, K. A. Drees, Y. Dutheil, W. Fischer C. Gardner, J. W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R. Hulsart, A. Kirleis J. Laster, C. Liu, Y. Luo, Y. Makdisi G. Marr A. Marusic, F. Meot, K. Mernick, R. Michnoff, M. Minty, C. Montag, J. Morris, S. Nemesure , P. Pile, A. Poblaguev, V. Ptitsyn, V. H. Ranjbar G. Robert-Demolaize, T. Roser, W. Schmidke, V. Schoefer, F. Severino, T. C. Shrey, D. Smirnov, K. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J. Tuozzolo G. Wang, M. Wilinski, S. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S. Y. Zhang