1. f Possible Proton Capabilities at Fermilab Dave McGinnis April 16, 2007

2. f Possible Proton Capabilities at Fermilab – McGinnis 2 Motivation  This talk outlines a plan to re-configure the Fermilab accelerator complex into an intense proton source.  The plan could simultaneously support a broad range of experimental programs  An intense (>1MW) 120 GeV beam for Neutrino production  An 8 GeV experimental facility with fast and slow spill capability and a flux of 2.5x10 20 protons/year  A 120 GeV slow spill beam with a flux of 0.3-1.0x10 20 protons/year  This plan should be viewed as a stepping stone in the Fermilab roadmap.  The time scale for this plan is 2012-2013  The total cost for this plan is in the <100M$ range

3. f Possible Proton Capabilities at Fermilab – McGinnis 3 Proton Rates  1 MW at 120 GeV requires 18.8x10 16 protons/hour  At 100% efficiency  2x10 7 seconds = 42 weeks x 130 hours/week  10x10 20 protons/year requires 18.3x10 16 protons/hour  at 2x10 7 seconds/year  20x10 10 pbars/hour requires 1.2x10 16 protons/hour  At a production of 17x10 -6  2x10 14 K + /year requires 0.3x10 20 protons/year  At a production of 6x10 -6 (40cm Be Target Separated Kaon beam – P. Cooper)  The present Fermilab Proton Source produces protons at an average rate of 9x10 16 protons/hour  It is possible to produce protons at a rate of 25x10 16 protons/hour with the  Proton Plan Upgrade,  The NOVA accelerator upgrades,  re-configuring the accelerator complex,

4. f Possible Proton Capabilities at Fermilab – McGinnis 4 Present Fermilab Proton Source  The FNAL Linac accelerates H- to 400 MeV  The FNAL Booster accelerates protons to 8 GeV.  The 8 GeV protons are used for MiniBooNE and to feed the Main Injector.  The Main Injector accelerates protons to 120 GeV.  The MI protons are used to make antiprotons (Collider) and neutrinos (MINOS).

5. f Possible Proton Capabilities at Fermilab – McGinnis 5 Present Fermilab Antiproton Source  The Tevatron Collider uses three antiproton source rings  Debuncher, Accumulator, and Recycler.  The Debuncher Ring collects antiprotons from antiproton target, bunch rotates the antiprotons and pre-cools them.  The Accumulator ring momentum stacks antiprotons collected from the Debuncher.  The Recycler Ring is a second accumulator ring that coalesces multiple Accumulator batches with electron cooling.  At the end of Run 2, all three of these rings become available

6. f Possible Proton Capabilities at Fermilab – McGinnis 6 Current Overall Booster Performance 9e16 Protons/Hour 4.6e12 Protons/Event 88% Efficiency 5.3 beam cycles/sec

7. f Possible Proton Capabilities at Fermilab – McGinnis 7 Current Booster Performance Overall NUMI Pulses MiniBoone PulsesStacking Pulses

8. f Possible Proton Capabilities at Fermilab – McGinnis 8 Current Proton Strategy  Because of space charge and aperture issues at the injection energy of the Booster, the strategy to increasing proton flux at Fermilab is longitudinal stacking at 8 GeV.  Longitudinal stacking at 8 GeV reduces the peak intensity requirement in the Booster  Results in a smaller required aperture for the Booster Smaller space charge tune shift Reduced requirements on acceleration efficiency  The key to longitudinal stacking is longitudinal phase space availability.  We currently use ~5-10% of the total 8 GeV longitudinal phase space available at Fermilab  Booster 12 eV-sec (use 100%)  Main Injector 300 eV-sec (use ~25%)  Recycler 400 eV-sec (use 0%)  Accumulator 190 eV-sec (use 0%)  Debuncher 550 eV-sec (use 0%)

9. f Possible Proton Capabilities at Fermilab – McGinnis 9 Slip Stacking  Slip Stacking is a technique to combine two Booster batches into a single batch  Slip Stacking is the technique that will be used for increasing the proton intensity in the Proton Plan and NOVA accelerator upgrades.  Slip Stacking takes advantage of the enormous unused phase space available in the Main Injector (Proton Plan) and the Recycler (NOVA accelerator upgrades).  Slip Stacking is a proven technology for the Run 2 upgrades  It has been used to accelerate over 4x10 13 protons in the Main Injector RF Phase Space Cartoon Booster Batch 1 Booster Batch 2 RF Bucket 1 RF Bucket 2 Final RF Bucket

10. f Possible Proton Capabilities at Fermilab – McGinnis 10 Main Injector Cycle Time  Slip Stacking into the Main Injector (Proton Plan) requires the Main Injector to hold at the injection energy while it is being filled  It takes 0.8 seconds to fill the Main Injector at 15Hz  The Main Injector can ramp up & down in less than 1.5 seconds  At the end of Run 2, the Recycler becomes available for slip stacking (NOVA accelerator upgrades).  As the Main Injector ramps up, delivers beam, and ramps down, the Recycler can be filled with 12 booster batches of protons by slip-stacking.  The Main Injector can be loaded in a single turn so the Main Injector cycle rate, hence beam power, is increased by 60%  In addition, the batches allocated for antiproton production can now be used for neutrino production so the total increase in beam power to the Neutrino target rises by 75%  None of this increase requires an increase in the peak intensity of the Main Injector.

11. f Possible Proton Capabilities at Fermilab – McGinnis 11 Multi-stage Proton Accumulator Motivation  Above 14x10 16 protons/hour, the number of batches stacked into the Recycler can not be increased further by slip stacking because of the rather severe amount of emittance dilution that is fundamental to the slip stacking process.  Momentum Stacking has much smaller longitudinal emittance dilution than slip stacking and can be used in place of slip stacking to achieve proton fluxes greater than 14x10 16  At the end of Run 2, the Accumulator becomes available for momentum stacking

12. f Possible Proton Capabilities at Fermilab – McGinnis 12 Mechanics of Momentum Stacking  The Accumulator was designed for momentum stacking  Large momentum aperture ~ 84 x 2.8 eV-Sec  Injection kickers are located in 9m of dispersion  Injection kickers do not affect core beam  Inject in a newly accelerated Booster batch every 67 mS onto the low momentum orbit of the Accumulator  The freshly injected batch is accelerated towards the core orbit where it is merged and debunched into the core orbit  Momentum stack 3-4 Booster batches T<133ms T=134ms T=0 Energy 1 st batch is injected onto the injection orbit 1 st batch is accelerated to the core orbit T<66ms 2nd Batch is injected T=67ms 2 nd Batch is accelerated 3 rd Batch is injected

13. f Possible Proton Capabilities at Fermilab – McGinnis 13 Multi-stage Proton Accumulator Scheme  Momentum stack in the Accumulator  Inject in a newly accelerated Booster batch every 67 mS onto the high momentum orbit of the Accumulator  Decelerate new batch towards core orbit and merge with existing beam  Momentum stack 3-4 Booster batches  Extract a single Accumulator batch Every 200 – 270 mS At an intensity of 3-4x a single Booster batch  Box Car Stack in the Recycler  Load in a new Accumulator batch every 200-270mS  Place six Accumulator batches sequentially around the Recycler  Load the Main Injector in a single turn

14. f Possible Proton Capabilities at Fermilab – McGinnis 14 Multi-stage Proton Accumulator Production Cycle

15. f Possible Proton Capabilities at Fermilab – McGinnis 15 Stages  Stage 1: The Proton Plan.  Booster aperture upgrades  Slip stacking in the Main Injector  Stage 2: NOVA Accelerator Upgrades  Slip Stacking in the Recycler  Main Injector “Load and Go” Main Injector Cycle time reduces from 2.1 sec to 1.3 sec  Stage 3: SNUMI  Proton momentum stacking in the Accumulator  Box Car stacking in the Recycler  Main Injector “Load and Go”

16. f Possible Proton Capabilities at Fermilab – McGinnis 16 Proton Flux Scenarios

17. f Possible Proton Capabilities at Fermilab – McGinnis 17 Booster Constraints

18. f Possible Proton Capabilities at Fermilab – McGinnis 18 Major Cost Drivers for Momentum Stacking  New transfer line into the Accumulator  The Booster is connected to the Accumulator via a re-built AP4 Line  The new AP4 line is about 240 meters in length Use magnets from the AP2 line for 8 GeV operation  New transfer line for extraction from the Accumulator  The AP5 line needs to be connected to the MI-8 line  The modification is about 200 meters in length Use magnets from the rest of AP3 AP4 Line AP5 Line A-D Line

19. f Possible Proton Capabilities at Fermilab – McGinnis 19 Major Cost Drivers for Momentum Stacking  Main Injector RF Power  The primary advantage of the slip stacking in the Recycler:  is to reduce the Main Injector cycle time  without increasing the Main Injector peak intensity  Momentum stacking in the Accumulator will increase the peak intensity in the Main Injector by 70%  It is possible to accelerate 1 MW of beam power with the current Main Injector RF system driven by a single tube and stay within the maximum rated specifications of the current power tetrode if active beam loading compensation is implemented and the power tetrodes are operated in Class C.  However, the peak anode current required by a single tube at 1 MW of beam power is substantially above normal operating experience for reliable operations.  The two tubes per cavity configuration provides substantial operating margin up to a beam power of 1.5 MW.

20. f Possible Proton Capabilities at Fermilab – McGinnis 20 8 GeV Experimental Facility  Even without the new AP4 and AP5 transfer lines, momentum stacking in the Accumulator can be used to build an 8 GeV experimental facility in what is currently the Antiproton Source tunnels.  This 8 GeV experimental facility could be used as the first step in a staged approach.  This 8 GeV proton source would use the Accumulator as a momentum stacker and convert the Debuncher into a slow- spiller.  This source would use existing transfer lines and not require any civil construction for the accelerator Debuncher Accumulator

21. f Possible Proton Capabilities at Fermilab – McGinnis 21 Momentum Stacking in The Accumulator T<133ms T=134ms T=0 Energy 1 st batch is injected onto the injection orbit 1 st batch is accelerated to the core orbit T<66ms 2nd Batch is injected T=67ms 2 nd Batch is accelerated 3 rd Batch is injected

22. f Possible Proton Capabilities at Fermilab – McGinnis 22 Resonant Slow Extraction from the Debuncher  Extraction scheme appears workable  Studying details of resonance generation  Also comparing 2 nd integer vs. 3 rd integer D4Q3 D4Q2D50QD5Q2 options: MI/TeV style septum - 80kV/1cm field region - 3 m long Short version of MI style Lambertson - ~.8T field region - +- 5” extraction aperture - 1 m long Wide aperture C magnet - ~.8 T - 2 m

23. f Possible Proton Capabilities at Fermilab – McGinnis 23 8 GeV Experimental Facility  During the 700kW NOVA era, it takes 0.8 seconds to fill the Recycler at 15Hz  Since the Main Injector ramp requires 1.33 seconds, the Recycler is empty and available for 0.53 seconds.  If the Recycler is connected to the current P1 line, beam can be sent to the Accumulator via the P1-P2-AP3 line (as it is done now) with no civil construction.

24. f Possible Proton Capabilities at Fermilab – McGinnis 24 The Recycler Boomerang* *M. Popovic, C. Ankenbrandt

25. f Possible Proton Capabilities at Fermilab – McGinnis 25 The Recycler Boomerang  Because the of the long time available (0.5 seconds) to extract, and no circulating beam in the Recycler, no fast kickers are required in the Recycler.  A simple switched set of dipoles is sufficient.

26. f Possible Proton Capabilities at Fermilab – McGinnis 26 SNUMI and the 8 GeV Experimental Facility  The 8 GeV Experimental Facility could also exist with SNUMI if the Main Injector cycle time is lengthened by 10% 22 batches = 1. 467s MI cycle Booster Batches Accumulator Recycler Debuncher 4.6  10 12 p/batch 0.1s1.367s NEUTRINO PROGRAM

27. f Possible Proton Capabilities at Fermilab – McGinnis 27 Proton Flux Scenarios

28. f Possible Proton Capabilities at Fermilab – McGinnis 28 Booster Constraints

29. f Possible Proton Capabilities at Fermilab – McGinnis 29 The Tevatron 120 GeV Stretcher Ring*  Running the Main Injector in slow spill mode requires a significant amount of Main Injector cycle time.  It has been suggested that the Tevatron can be operated as a slow-spiller at 120 GeV*  The Tevatron as a slow-spiller would greatly reduce the cycle time load of a slow-spill program.  The Tevatron can be filled by two consecutive Main Injector cycles  It should be noted that beam transferred to SY120 from the Main Injector passes through the Tevatron Injection Lambertson Magnet.  For today’s SY120 operation, this magnet is left off, and the beam passes straight through and up into the SY120 beam line.  In order to extract beam from the Tevatron this magnet needs to be turned on with reversed polarity.  An electrostatic septum would kick the resonant particles into the field region of this same magnetic septum and direct them up toward the SY120 beam line.  The natural place for the electrostatic septum, assuming half- integer resonant extraction, would be the C0 straight section. *Mike Syphers Beams Document 2222

30. f Possible Proton Capabilities at Fermilab – McGinnis 30 The Tevatron 120 GeV Stretcher Ring  Since there will be no ramping of the Tevatron, then effects such as “snap-back,” tune and chromaticity drift, etc., will be of little consequence, and the quench margin will be much higher.  The main drawback of this scenario is the operating cost of the cryogenic system  The power use of the Tevatron cryogenics system is dominated by the heat leak inherent in the magnets  The two-phase helium system cannot function above about 5K.  Possible Scenario:  Two Main Injector cycles out of every twenty used to fill the Tevatron with 4.9x10 13 protons Produces 10MHz of flux for a separated Kaon Beam  Eighteen Main Injector cycles out of every twenty used for the Neutrino program for a 120GeV beam power of 940 kW  Four Booster Batches out of every 22 batches used for the 8 GeV Experimental facility to produce 4.6x10 16 protons/hour at 8 GeV

31. f Possible Proton Capabilities at Fermilab – McGinnis 31 Summary  Reconfiguring the present collider complex  Accumulator as a Momentum stacker  Recycler as a Box Car Stacker  Debuncher as an 8 GeV Slow Spiller  Tevatron as a 120 GeV Slow Spill Stretcher Ring  could be used to simultaneously source a wide variety of proton-based programs  Neutrino program ranging from 700-1200kW of 120 GeV proton beam  8 GeV slow or fast spill program with a flux of 4.6x10 16 protons/hour  120 GeV slow spill program with an average flux of 2 – 5.0x10 12 protons/second  These fluxes are achieved by taking advantage of Proton Plan upgrades to run the Booster at 15Hz