October 4-5, Overview of ARRA funded AIPs at C-AD Wolfram Fischer October 4, 2010

October 4-5, Wolfram Fischer 2 2 superconducting 3.8 km rings 2 large experiments 100 GeV/nucleon Au 250 GeV polarized protons Performance defined by 1. Luminosity L 2. Proton polarization P 3. Versatility Au-Au, d-Au, Cu-Cu, polarized p-p (so far) 12 different energies (so far) Relativistic Heavy Ion Collider 1 of 2 ion colliders (other is LHC), only polarized p-p collider

October 4-5, Outline Heavy ion performance and upgrade plans ARRA AIP project: Horizontal stochastic cooling Project Manger: A. Zaltsman Polarized proton performance and upgrade plans ARRA AIP project: Electrons lens Project Manager: W. Fischer Overall Accelerator Improvement Project (AIP) plan, and ARRA funded AIPs

October 4-5, RHIC heavy ions – luminosity evolution L NN = L N 1 N 2 (= luminosity for beam of nucleons, not ions) reached design in x design in 2010

October 4-5, RHIC luminosity and polarization goals ParameterUnit AchievedUpgraded Au-Au operation (2010)(>=2012) Energy GeV/nucleon 100 No of bunches … 111 Bunch intensity Average L cm -2 s p  - p  operation (2009)(>=2011/12)(>=2014) Energy GeV 100 / No of bunches … 109 Bunch intensity / / Average L cm -2 s / 5530 / / 300 Polarization P % 55 / 3470

October 4-5, RHIC heavy ions – luminosity limits 1.Intrabeam scattering Leads to debunching and transverse emittance growth Bunched beam stochastic cooling during stores 2.Chromatic abberations with small  * With  * = 60 cm could not correct nonlinear chromaticity with beam-based method (momentum aperture too small), retreated to  * = 70 cm Include chromatic corrections in lattice design 3.Instabilities at transition Limit bunch intensity, driven by impedance and electron clouds Reduce SEY in arcs (straights are NEG coated), feedback intensity loss after transition at end of bunch trains 2004 no cooling

October 4-5, RHIC – 3D stochastic cooling for heavy ions M. Brennan, M. Blaskiewicz, F. Severino, Phys. Rev. Lett (2008); PRST-AB, PAC, EPAC longitudinal kicker (closed) horizontal kicker (open) horizontal and vertical pickups longitudinal pickup 5-9 GHz, cooling times ~1 h vertical kicker (closed) Y h+v pickups B h+v kickers B h+v pickups Y h+v kickers

October 4-5, RHIC – bunched beam stochastic cooling for heavy ions Longitudinal cooling since 2007 First transverse (vertical) cooling in Jan 2010 M. Brennan M. Blaskiewicz K. Mernick et al. So far stochastic cooling increased average store luminosity by factor 2 Expect another factor 2 with full 3D cooling Open issues after 2010 run: Vacuum leaks at feedthroughs Mechanical motion of long. kickers Cross-talk between Blue and Yellow vertical system (addressed by 100 MHz shift in Blue) Construction, installation, and commissioning of horizontal systems

October 4-5, Other heavy ion upgrades Electron Beam Ion Source (EBIS) [J. Alessi et al.] –Replaces existing Tandems as pre-injector –Had CD-4 review in September 56 MHz SRF [I. Ben-Zvi, A. Zaltsman et al.] –Provides additional longitudinal focusing against IBS –30-50% increase in average store luminosity Low energy operation [C. Montag/T. Satogata, A. Fedotov et al.] –First physics operation below nominal injection energy in 2010 –Electron cooling considered for future if program continues/grows Beam size reduction at interaction point –Need better control of nonlinear chromaticity Feedbacks [M. Minty, A. Marusic et al.] –First use of simultaneous orbit/tune/coupling/chromaticity feedback for ramp setup

October 4-5, RHIC polarized protons – luminosity and polarization L peak = 85x10 30 cm -2 s -1 L peak = 50x10 30 cm -2 s -1 FOM = LP 4 (longitudinally polarized beams)

October 4-5, RHIC luminosity and polarization goals ParameterUnit AchievedUpgraded Au-Au operation (2010)(>=2012) Energy GeV/nucleon 100 No of bunches … 111 Bunch intensity Average L cm -2 s p  - p  operation (2009)(>=2011/12)(>=2014) Energy GeV 100 / No of bunches … 109 Bunch intensity / / Average L cm -2 s / 5530 / / 300 Polarization P % 55 / 3470 Had a goal of 60 here until 2009 – but low luminosity lifetime with low  *.

October 4-5, Special devices for polarized protons: source, polarimeters, snakes, rotator, flipper

October 4-5, RHIC protons – polarization and luminosity limits 1.AGS : proton bunches with high intensity, high polarization and low emittance polarized source upgrade (under way) AGS horizontal tune jump system (tested in ) 2.RHIC: polarization transmission to 250 GeV acceleration near 2/3 resonance (tested in 2010) 3.RHIC: intensity transmission to 250 GeV beam dump system modifications (thicker beam pipe in dump) Yellow ramp transmission (9 MHz rf system) 4.RHIC: peak luminosity and luminosity lifetime reached lower  * limit at 100 GeV (not necessarily a problem at 250 GeV) electron lenses allow for larger beam-beam parameter

October 4-5, Electron lens in RHIC IP8 -IP10  y = 10.9  IP6-IP10  x = 19.1  Basic idea: In addition to 2 beam-beam collisions with positively charged beam have another collision with a negatively charged beam with the same amplitude dependence. 2 electron lenses installed in Tevatron (not used for head-on beam-beam compensation) Exact compensation possible for: short bunches  x,y = k  between p-p and p-e collision no nonlinearities between p-p and p-e same amplitude dependent kick from p-p, p-e Only approximate realization possible

October 4-5, Electron lens in RHIC e-beam p-beam partial compensation of head-on beam-beam goal of 2x luminosity increase together with source upgrade (allowing for higher bunch intensity with good polarization) critical: relative beam alignment (Tevatron experience) requires straight solenoid field lines, good instrumentation (bremsstrahlung and/or halo monitor – C. Montag, P. Thieberger, D. Gassner) DC gun: 7 kV, 0.6 A 6 T solenoid, straightness ~0.1 rms beam size collector

October 4-5, Overview AIPs FY2009 – 2015 [FY2011: Presidents budget, FY : 3.5% annual escalation] ARRA AIPs accelerated luminosity upgrades for heavy ions (stochastic cooling) polarized protons (electron lens) by about 2 years 2 nd electron lens, need $700k reprogramming from operations to AIP in FY2011

October 4-5, RHIC stochastic cooling and 56 MHz SRF upgrades Obtain RHIC II performance (= order of magnitude more heavy ion luminosity) without major upgrade (previously planned with electron cooling, ~ $100M): Upgradefundingcompletion typeamountFiscal Year Previous and current Y longitudinal SCR&D$0.5M B longitudinal SCAIP$1.0M Y vertical SCR&D$1.6M B vertical SCAIP$1.5M B+Y horizontal SCAIP (ARRA)$4.0M (planned) 56 MHz SRFAIP$4.0M (planned) Future B+Y long. SC kicker upgradeCapital$600k (planned) Low noise cryo for SRFAIP$1.5M (planned) B+Y long. SC 12 GHzAIP$3.0M (planned)

October 4-5, RHIC electron lenses – 2 AIPs (1 ARRA + 1 regular) 1 st electron lens (ARRA AIP): Funding: $4.0M (06/25/09) Pacing item: superconducting solenoid Had planned to purchase in industry Received only 1 bid from 9 bidders contacted (various reasons for no bids – missing production capacity, exchange rate, …) Bid at about 3x budgeted value (budget for sc solenoid guided by 2 benchmarks: EBIS spare solenoid, Tevatron solenoids for electron lens) Failed solenoid bidding also delayed project Solenoid now build in Superconducting Magnet Division (allows for technically better magnet) Expected completion: 11/2012 [Note: Can raise bunch intensity with one (two) beams with one (two) electron lenses.]

October 4-5, RHIC electron lenses – 2 AIPs (1 ARRA + 1 regular) 2 nd electron lens (AIP): Funding: $3.1M (planned for FY2011/12 AIP) Engineering and tooling cost covered by 1 st lens Expected completion: 11/012 (same as 1 st lens) DC electron gun Electron collector

October 4-5, Summary 2 ARRA AIPs at BNL C-AD –Horizontal stochastic coolingProject Manager: A. Zaltsman –Electron lens Project Manager: W. Fischer ARRA AIPs are essential for RHIC luminosity upgrade –Horizontal stochastic cooling for heavy ions (~2x L avg ) –Electron lens for polarized protons (up to 2x L avg ) Overall technical design of systems is complete, components are on order or being manufactured –Horizontal stochastic cooling based on vertical stochastic cooling –Electron lens based on Tevatron electron lenses, and EBIS Budget and schedule developed for both projects –Major revision was needed for EL after bids for superconducting solenoid received –Planned completion for both projects by end of 2012 Both projects are embedded in departmental planning and safety procedures