1. Fermilab and Muons Booster, Proton Driver (MECO, PRISM/PRIME, …) David Neuffer Fermilab

2. 2 Outline  Fermilab: Protons and Muons  Present Proton source: Booster  Future Source : Proton Driver  Possible configurations, intensities

3. 3 Present Proton Source: 8 GeV Booster NOW: 400 MeV Linac  8 GeV Booster (C=454m) produces 80 bunches (53 MHz)  Currently Limited by losses in Booster  5Hz, ~ 3  10 12 / pulse: ~1.5×10 20 p/year (0.02MW)  15Hz, 5  10 12 /pulse possible (0.1MW) (6  10 13 protons/s)  NUMI, MiniBOONE, Tevatron p- source  Tevatron, MiniBOONE will be completed…  Capacity for other experiments …  But 15Hz cycle limits applications Linac – 400MeV Booster – 8 GeV Main Injector, MiniBOONE

4. 4 Proton Driver and Muon beams  8GeV Linac can produce streams of 1.5×10 14 8GeV protons at up to 10Hz  > 10 22 protons/year  Neutrino Physics: main goal  But: Only 1/15 of these needed for Main Injector/NUMI  Are there muon beam experiments that could use this intensity ??  Tertiary muon beams:  P + X → π  π → μ + ν  10 -1 μ/p → 10 21 μ/year or more (other experiments will also be possible)

5. 5 Primary Parameter List (Foster, March 2005 reference)

6. 6 Proton Driver Parameters 8 GeV Superconducting LINAC EnergyGeV8 Particle Type H- Ions, Protons, or Electrons Rep. RateHz2.5 to 10 Active Lengthm671 Beam CurrentmA25 Pulse Lengthmsec3 to 1 Beam IntensityP / pulse1.5E+14 (can also be H-, P, or e-) P/s1.5E+15 Linac Beam PowerMW avg.0.5 to 2 MW peak200 MAIN INJECTOR WITH 8 GeV LINAC MI Beam EnergyGeV120 MI Beam PowerMW2.0 MI Cycle Timesec1.5 filling time = 1msec MI Protons/cycle1.5E+14 5x design MI Protons/hrP / hr3.6E+17 H-minus Injectionturns90 MI Beam CurrentmA2250

7. 7 Detailed  source design does not exist Straw man design worked out for the front end of a factory, supported by MARS simulations (Brice, Geer, Paul, Taylor, Fermilab-Conf-04-196-E) Target + capture solenoid + drift (forward capture) 1.5 x 10 22 protons/year at 8 GeV yields ~3 x 10 21 muons/year. Charged particle spectra at end of decay channel Generic High intensity muon beam ~0.2 µ/p

8. 8 LFV:   A  e  A can use high intensity ExperimentI 0 /I m  T [ns]  T [  s] p  [MeV]  p  /p     A  e  A   e    eee   e     e  10 21 10 17 10 16 < 10 -10 n/a < 10 -4 < 100 n/a < 1000 > 1 n/a > 20 < 80 < 30 < 5 < 10 1…2  10 14 < 10 -4 100> 2030< 10 g  -2 EDM 10 15 10 16 < 10 -7 < 10 -6 < 50 > 10 3 3100 <1000 < 2 Desirable Beam Characteristics But bunched beam is needed

9. 9 MECO expt. (BNL-based proposal) Superconducting Production Solenoid (5.0 T – 2.5 T) Muon Stopping Target Muon Beam Stop Crystal Calorimeter Superconducting Transport Solenoid (2.5 T – 2.1 T) Superconducting Detector Solenoid (2.0 T – 1.0 T) Collimators Tracker Time structure

10. 10 PRISM-PRIME (Y. Kuno et al.) High intensity pulsed proton beam (bunch length <10ns) 100-1000Hz bunches producing π —> μ bunches Phase rotation with rf field: Δp/p : ±20%  ± 2% P = 68 MeV/c ±20%

11. 11 Proton Beam requirements  MECO experiment  Requires pulses of ~8 GeV protons (<30ns long) every ~1μs (1.4μs) –Obtained by slow extraction of short bunches (in AGS)  Design requires 4  10 13 p/s, 2  10 -3 captured μ’s/proton  10 5 μ/pulse (~5  10 7 p/pulse)  ~8  10 17 μ/year from ~4  10 20 p/year  PRISM-PRIME experiment  Requires proton pulses (<10ns long) at 10 3 /s (~1ms) –4  10 14 p/s (50GeV) 10 -2 to 10 -3 μ’s/proton –Up to 10 22 p/year, > 10 19 μ/year  Single-turn extraction of short bunches (<10ns)  Up to 4  10 9 μ/pulse (~ 10 12 p/pulse)  Both require pulsed beams, proton linac beam must be repackaged in an accumulator ring

12. 12 Recycler as accumulator ring ?  8GeV Linac produces 1ms pulses at 10 Hz  H - injection into Recycler  1ms fills circumference –(100 turns)  Bunch beam into pattern required for expt.  Harmonic 10 buncher for MECO, slow extraction  Harmonic 100 buncher for PRIME, single bunch extraction CircumferenceC=2πR ave 3320m MomentumP8.89 GeV/c Rev. frequency, Period f0T0f0T0 89.8 kHz 11 μs Slip factorη=1/γ 2 - 1/γ t 2 0.0085 Tunesν x, ν y 25.4,24.4 But: Recycler circumference is large 100ms may be too short a time for bunching

13. 13 Space Charge Difficulty  Space Charge tune shift:  Parameters: N tot =1.5  10 14,ε N =20π mm-mrad  MECO: 30ns/1μs : B F = 0.03 → δν = 4 : too large  Reduce N to 1.5  10 13 → δν = 0.4  PRISM/PRIME 10ns bunches, 100/ring  B F = 0.1 → δν =1.2: too large (but closer)  Use larger ε N, smaller N tot, N tot  1  10 14 OK  Smaller circumference proton ring could be better

14. 14 Recycler – Bunching for ~MECO  Harmonic 10 buncher (0.9MHz)  Barrierbucket rf  Bunch for ~1s  (V rf ramps to ~30kV)  Bunch lengths reduced to ~50ns rms (MECO wants ~30ns full width.)  Could then extract bunches in slow extraction over ~1s  OK for  10 13 protons/s

15. 15 Recycler – Bunching (~for PRISM)  Harmonic 100 buncher (9MHz)  Bunch for 0.1s  (V rf ramps to 140kV)  Bunch lengths reduced to ~5ns rms (Prism wants < 10ns full width.)  Could then extract bunches one at a time over ~0.1s  Uses 1/2 the possible linac pulses (500 bunches/s for PRISM) (100 at 5Hz)  ~5  10 14 p/s possible

16. 16 Other potential proton storage schemes  Accumulator or Debuncher (C= ~454m) after 2010…  Large aperture machines  t  5  Difficult to inject H - (must bend beam from Linac) (B ~600m)  Could take debunched protons from Recycler or Main Injector(in ~450m chunks)  Bunch into pattern needed for experiments  Bunching easier than Recycler  New 8 GeV Storage Ring ??

17. 17 New 8 GeV Accumulator/buncher/stretcher  FFAG  Type: FODO racetrack,  Superferric arcs  nonscaling  H - injection into NewRing (10Hz)  700 turns  δν = 0.4 at B F =0.15 (σ=1.5ns)  Harmonic 42 buncher for PRISM, single bunch extraction (40ns spacing)  Slow extraction, single bunch extraction modes CircumferenceC=2πR ave ~454m MomentumP8.89 GeV/c rf frequency, Voltage h=42 V 0 26 MHz 1MV Slip factorη=1/γ 2 - 1/γ t 2 -0.02 Tunesν x, ν y 6, 8 aperturea, b~3,2cm

18. 18 Proton Linac (H - ) NewRing (P)

19. 19 Fermilab – w/o SRF linac proton driver Upgrade: Linac  8 GeV Booster  From 5Hz ~ 3  10 12 / pulse  15Hz, 5  10 12 /pulse possible (0.1MW) (6  10 13 protons/s)  Single turn extraction is 1.5  s  onto  production target (~ MiniBOONE), then  e target  Adapt to  e conversion experiment  Not very well suited to ~1  s µ-decay  Most  ’s decay before end of injection pulse  ~1/3 of full pulse probably useful CircumferenceC=2πR ave ~454m MomentumP8.89 GeV/c rf frequencyh=8453 MHz Slip factorη=1/γ 2 - 1/γ t 2 -0.022 Tunesν x, ν y 6.6, 6.8 aperturea, b~3,2cm

20. 20 Fermilab - Beam from Booster  For pulsed experiments, need a storage ring  Could use Accumulator, Debuncher (450m circ.)?  Scenario:  Transfer into ring, bunch, extract short bunches onto targets  ~80bunches, 15 Hz = 1200Hz (~PRISM) (6×10 10 p/bunch)  For ~MECO, bunch into single bunch? (<100ns out of 1.5µs) –Slow extraction  Possible Long-term Future: New 8 GeV Booster  With 1 GeV linac ??  larger apertures, larger injection energies, deeper tunnel (5  10 13 / pulse ??)  (1MW ??)  With new storage ring

21. 21 Summary  Muon Beams at Fermilab could be developed  Potential muon beam facilities could be constructed  ~MECO or PRISM, etc. … could be hosted  More Detailed design needed  Proton Collection –Recycler …. –New Stretcher/Buncher ring ??  Beam line(s)  Experimental area(s)

22. 22 References  W. Foster et al., Proton Driver http://tdserver1.fnal.gov/project/8GeVLinac/DesignStudy/  W. Molson, “The MECO Experiment to Search for  - N  e - N with 10 -17 Sensitivity”, U. Va. Seminar, June 2004  ‘RSVP’ Rare Symmetry Violating Processes (MECO- KOPIO) NSF proposal, October 1999.  PRISM Working group  “An Experimental Search for the μ − −e − Conversion Process at an Ultimate Sensitivity of the Order of 10 −18 with PRISM”, The Prime Working Group, Jan. 1, 2003.  R. Ray & D. Roberts, Proton Driver physics study

23. 23 PRISM rf-rotation P = 68 MeV/c ±20%  t = ±12ns (5ns rms) PµPµ  p=±1.9%  p=±3.4% 5-turns, 38% beam decay6-turns, 44% decay