Post on 17-Jan-2016
October 4-5, 20101
Overview of ARRA funded AIPs at C-AD
Wolfram Fischer
October 4, 2010
October 4-5, 20102Wolfram Fischer 2
2 superconducting 3.8 km rings2 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 Collider1 of 2 ion colliders (other is LHC), only polarized p-p collider
October 4-5, 20103
Outline
• Heavy ion performance and upgrade plans
ARRA AIP project: Horizontal stochastic coolingProject Manger: A. Zaltsman
• Polarized proton performance and upgrade plansARRA AIP project: Electrons lensProject Manager: W. Fischer
• Overall Accelerator Improvement Project (AIP) plan,and ARRA funded AIPs
October 4-5, 20104
RHIC heavy ions – luminosity evolution
LNN = L N1N2 (= luminosity for beam of nucleons, not ions)
reached design in 2001
10x design in 2010
October 4-5, 20105
RHIC luminosity and polarization goals
Parameter Unit Achieved Upgraded
Au-Au operation (2010) (>=2012)
Energy GeV/nucleon 100 100
No of bunches … 111 111
Bunch intensity 109 1.1 1.0
Average L 1026cm-2s-1 20 40
p- p operation (2009) (>=2011/12) (>=2014)
Energy GeV 100 / 250 100 / 250 250
No of bunches … 109 109 109
Bunch intensity 1011 1.3 / 1.1 1.3 / 1.5 2.0
Average L 1030cm-2s-1 24 / 55 30 / 150 60 / 300Polarization P % 55 / 34 70 70
October 4-5, 20106
RHIC heavy ions – luminosity limits
1. Intrabeam scatteringLeads to debunching and transverse emittance growth Bunched beam stochastic cooling during stores
2. Chromatic abberations with small b*
With b* = 60 cm could not correct nonlinear chromaticity with beam-based method (momentum aperture too small), retreated to b* = 70 cm Include chromatic corrections in lattice design
3. Instabilities at transitionLimit bunch intensity, driven by impedance and electron clouds Reduce SEY in arcs (straights
are NEG coated), feedback
intensity loss after transitionat end of bunch trains
2004 no cooling
October 4-5, 20107
RHIC – 3D stochastic cooling for heavy ions
M. Brennan, M. Blaskiewicz, F. Severino, Phys. Rev. Lett. 100 174803 (2008); PRST-AB, PAC, EPAC
longitudinal kicker
(closed)
horizontal kicker (open)
horizontal andvertical pickups
longitudinal pickup
5-9 GHz, cooling times ~1 h
verticalkicker
(closed)
Y h+v pickups
B h+v kickers
B h+v pickups
Y h+v kickers
October 4-5, 20108
RHIC – bunched beam stochastic cooling for heavy ions
• Longitudinal cooling since 2007• First transverse (vertical) cooling in 2010
14 Jan 2010
M. BrennanM. 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, 20109
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, 201010
RHIC polarized protons – luminosity and polarization
Lpeak = 85x1030cm-2s-1
Lpeak = 50x1030cm-2s-1
FOM = LP4
(longitudinally polarized beams)
October 4-5, 201011
RHIC luminosity and polarization goals
Parameter Unit Achieved Upgraded
Au-Au operation (2010) (>=2012)
Energy GeV/nucleon 100 100
No of bunches … 111 111
Bunch intensity 109 1.1 1.0
Average L 1026cm-2s-1 20 40
p- p operation (2009) (>=2011/12) (>=2014)
Energy GeV 100 / 250 100 / 250 250
No of bunches … 109 109 109
Bunch intensity 1011 1.3 / 1.1 1.3 / 1.5 2.0
Average L 1030cm-2s-1 24 / 55 30 / 150 60 / 300Polarization P % 55 / 34 70 70
Had a goal of 60 here until 2009 – but low luminosity lifetime with low b*.
October 4-5, 201012
PHENIX (p)
AGS
LINACBOOSTER
Pol. H- Source
Solenoid Partial Siberian Snake
200 MeV Polarimeter
Helical Partial Siberian Snake
Spin Rotators(longitudinal polarization)
Siberian Snakes
Spin Rotators(longitudinal polarization)
Strong AGS Snake
RHIC pC Polarimeters
Absolute Polarimeter (H jet)
STAR (p)
AGS Polarimeters
Spin flipper
Special devices for polarized protons:source, polarimeters, snakes, rotator, flipper
October 4-5, 201013
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 2009-10)
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 b* limit at 100 GeV (not necessarily a problem at 250 GeV)
electron lenses allow for larger beam-beam parameter
October 4-5, 201014
Electron lens in RHIC
IP8 -IP10 Dyy = 10.9 p
IP6-IP10 Dyx = 19.1 p
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• Dyx,y = kp 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, 201015
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, 201016
Overview AIPs FY2009 – 2015
[FY2011: Presidents budget, FY2012-15: 3.5% annual escalation]
ARRA AIPs accelerated luminosity upgrades for• heavy ions (stochastic cooling)• polarized protons (electron lens)
by about 2 years
2nd electron lens, need $700k reprogramming from operations to AIP in FY2011
October 4-5, 201017
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):
Upgrade funding completion
type amount Fiscal Year
Previous and current
Y longitudinal SC R&D $0.5M 2004-06 2007
B longitudinal SC AIP $1.0M 2006-07 2008
Y vertical SC R&D $1.6M 2009 2010
B vertical SC AIP $1.5M 2009 2010
B+Y horizontal SC AIP (ARRA) $4.0M 2009 2012 (planned)
56 MHz SRF AIP $4.0M 2008-11 2013 (planned)
Future
B+Y long. SC kicker upgrade Capital $600k 2011 2012 (planned)
Low noise cryo for SRF AIP $1.5M 2011-12 2013 (planned)
B+Y long. SC 12 GHz AIP $3.0M 2014-15 2016 (planned)
October 4-5, 201018
RHIC electron lenses – 2 AIPs (1 ARRA + 1 regular)
• 1st 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, 201019
RHIC electron lenses – 2 AIPs (1 ARRA + 1 regular)
• 2nd electron lens (AIP):
• Funding : $3.1M (planned for FY2011/12 AIP)
• Engineering and tooling cost covered by 1st lens• Expected completion: 11/012 (same as 1st lens)
DC electron gun
Electron collector
October 4-5, 201020
Summary
• 2 ARRA AIPs at BNL C-AD– Horizontal stochastic cooling Project Manager: A. Zaltsman– Electron lens Project Manager: W. Fischer
• ARRA AIPs are essential for RHIC luminosity upgrade– Horizontal stochastic cooling for heavy ions (~2x Lavg)
– Electron lens for polarized protons (up to 2x Lavg)
• 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