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This talk discusses the Fermilab Booster, the only machine at Fermilab to accelerate protons from 400 MeV to 8 GeV, and the efforts to increase its proton capacity and address radiation and activation issues.
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Fermilab Booster Status & PlansBob Webber Fermilab Beams Division Seminar 11/2/99 Beams Division Seminar 11/2/99
This is a talk about --- • A grandiose new dream machine - NOT • An in-depth analysis of Booster beam physics - NOT • The oldest accelerator encountered by protons at Fermilab (pushing 30 years old) • The only machine at Fermilab for the next 5 years or more to accelerate protons from 400 MeV to 8 GeV • Status and activities in the effort to squeeze more protons (per pulse & per hour) out of this machine • “Probably the finest accelerator in the entire known universe as we know it.” (Tomlin, 1984) Beams Division Seminar 11/2/99
Fermilab Booster Parameters • 200 MeV -- 8 GeV proton synchrotron built ~ 1970 • Combined function magnetic lattice with γt = 5.4 • 75 meter average radius • 15Hz resonant magnetic cycle • Harmonic 84 RF system, 38 - 53 Mhz • Adiabatic capture of injected beam by Booster RF • Upgrade to H- charge exchange injection in 1977 • Upgrade to 400 MeV injection in 1993 • Primary extraction point relocated to Long 3 in 1997 Beams Division Seminar 11/2/99
How Many Protons? • Estimated high during MR fixed target operation • ~ 3E12ppp @ 2.5Hz ( 2.9E16 pph) • 1.3µA average current for 10kW at 8 GeV • Current operational demand • 2E12ppp @ 0.5Hz ( 3.6E15 pph) • 0.16µA for 1.3kW at 8 GeV • Early Run II demand (Booster’s Y2K problem!) • 5E12ppp @ .7 Hz (1.25 E16 pph) • .55µA for 4.3kW at 8 GeV • Year 2002+ demand (MiniBooNE + NUMI) • 5E12ppp @ 8 Hz (14.5E16 pph) • 6.4µA for 51kW Beams Division Seminar 11/2/99
So What’s the Problem? • Present record pulse intensity is barely 5E12 • Typical 400 MeV injection to 8 GeV extraction efficiency is 80% @ 1E12ppp to 60% @4E12ppp • Inadequate passive radiation shielding throughout Booster • Numerous pulsed magnet, power supply, and RF system designs currently limit pulse repetition rate • Aging accelerator power, controls, and infrastructure systems and components Beams Division Seminar 11/2/99
Booster Low Intensity Charge Snapshot Beams Division Seminar 11/2/99
Booster High Intensity Charge Snapshot Beams Division Seminar 11/2/99
Booster Operating Near 5E12 ppp A/D on Booster intensity signal saturates at 5.23E12 Beams Division Seminar 11/2/99
Booster Radiation and Activation Issues • Fermilab HEP program, within the coming year, will be limited by allowed radiation around Booster • demand for proton throughput will rise order of magnitude in next three years relative to historic levels in 90’s • office and beamline constructions and tightened radiation exposure regulations exacerbate original situation • little option for additional shielding • Component activation will be a serious concern at NUMI/MiniBooNE levels • Booster beam loss reduction and control key to entire future planned Fermilab high energy physics program! Beams Division Seminar 11/2/99
1998 Booster Shielding Assessment • Driving factors • old assessment inadequate for anticipated proton requirements • re-location of extraction point for beam to Main Injector • old assessment relied on loss signature at few locations limiting machine development flexibility, e.g. high energy orbit changes and magnet moves • Numerous soil activation measurements • Complete shielding geometry assessment for entire ring • Many measurements to understand radiation patterns and levels for “normal” and “accident” conditions • Resulted in array of ~50 interlocked radiation detectors Beams Division Seminar 11/2/99
Typical Booster Lattice Period and Apertures Also points of maximum dispersion Beams Division Seminar 11/2/99
Injection Energy Radiation Patterns Beams Division Seminar 11/2/99
Energy Dependent Loss Patterns Beams Division Seminar 11/2/99
Shielding Installation -- Summer 1998 Beams Division Seminar 11/2/99
Booster Interlocked Radiation Detectors Beams Division Seminar 11/2/99
Causes of Beam Loss • Poor orbit control • closed orbit changes dramatically vs. time in cycle • low field orbit is regularly modified by normal tuning • small dynamic apertures • Historically no beam gap synchronized to extraction kickers -- systematic 2% beam loss at extraction septum • Longitudinal instabilities after transition at high current • RF capture inefficiencies • Space charge blowup ? • ?? Help Here Please !! Beams Division Seminar 11/2/99
Toward Control of Beam Loss Problem • Continued aperture improvements • magnet moves to remove aperture constraints • study increased RF cavity aperture • improved orbit control • orbit adjustment program • ramped correctors w/ beam position feedback • improved main magnet control • Create and synch beam gap with extraction kicker • presently able to create notch at 400 MeV after injection with short kicker • investigating laser neutralization gap creation • synchronization to circulating Main Injector beam is complicated and narrowly constrained by beam dynamics Beams Division Seminar 11/2/99
Laser for Possible Gap Creation Beams Division Seminar 11/2/99
Extraction Losses vs. Gap in Beam Beams Division Seminar 11/2/99
Active Gap Cogging in Booster FEEDBACK ON POST TRANSITION GAIN = 23 Final configuration at one turn CH 2 Cogging turns corrected error signal This picture corresponds to that on slide 3 Beams Division Seminar 11/2/99
Active Gap Cogging in Booster 84 buckets (one turn) Zero initial notch phase error FEEDBACK ON CH 2 Cogging turns corrected error signal Beams Division Seminar 11/2/99
Toward Control of Beam Loss Problem • Improved longitudinal dampers • Scraper/collimator • control loss of particles that cannot be retained • design is commencing based on new Booster model • Improved beam physics models for space charge, etc. applicable to Booster • New BLM transducer and data acquisition system • ability to quantitatively see and record when and where beam losses occur under complicated operating scenarios is essential to facilitate and measure progress Help Here Please !! Help Here Please !! Beams Division Seminar 11/2/99
Pulse Repetition Rate Requirements • Booster main magnets cycle continuously at 15Hz, nearly all pulsed devices do not • Pre-pulse requirements result in higher pulse repetition rates for power equipment than for beam • Run II p-bar production in 2000 requires ~ 0.7 Hz beam rate and 2 Hz power equipment rate capability • Run II + MiniBoone in 2002 requires ~ 5.7 Hz beam and 7.5 Hz power equipment capability • Run II + MiniBooNE + NUMI in 2003 requires 8.6 Hz beam and 10.7 Hz power equipment capability Beams Division Seminar 11/2/99
Pulse Rep Rate Test Results (TM2074) Beams Division Seminar 11/2/99
Extraction Magnet Test Setup Beams Division Seminar 11/2/99
MP01/2 End Field Measurements Beams Division Seminar 11/2/99
Fast TimeLine for RF Tests Beams Division Seminar 11/2/99
Fast Timeline RF Bias Supply Current Beams Division Seminar 11/2/99
Pulse Repetition Rate Limits & Solutions • Additional RF system tests performed last month with BD RF Department • New extraction pulsed septum magnets under design with assistance of Technical Division for installation during Run II detector roll-in in Fall 2000 • Pulsed septa and ORBMP power supply and transmission systems under review by BD EE Support • ORBMP magnet capability must be somehow tested • Controls system and data acquisition implications must be understood and any shortcomings addressed, e.g. BMP system will not work at 15 Hz Beams Division Seminar 11/2/99
Aging and Maintenance Issues • Gradient magnet power supplies replaced in 1998 • LCW heat exchangers at CUB presently being replaced • Gallery cooling improvements in progress • RF power systems in need of major rebuild especially to obtain necessary reliability under higher duty cycle operation and higher residual radiation levels in tunnel • Gradient magnet current regulation system needs to be replaced with non-obsolete components and spares • Much of the Low level RF system needs to be replaced with non-obsolete components and spares • Vacuum controls need to be replaced Beams Division Seminar 11/2/99
New East Gallery GMPS Installation Beams Division Seminar 11/2/99
GMPS Interlocks Maintenance Beams Division Seminar 11/2/99
New 8 GeV Radiation Damage Facility Beams Division Seminar 11/2/99
Summary • Booster beam loss reduction and control and equipment maintenance and upgrades are key to entire future planned Fermilab high energy physics program! • Booster -- “Probably the finest accelerator in the entire known universe as we know it.” NEEDS YOU! Beams Division Seminar 11/2/99