1. Fermilab, Proton Driver, Muon Beams, Recycler David Neuffer Fermilab NufACT05

2. 2 Proton Driver and Muon beams  8GeV Linac can produce streams of 1.5×10 14 8GeV protons at 10Hz  > 10 22 protons/year  Only 1/15 of these needed for Main Injector  Are there muon beam experiments that could use this intensity ??  Tertiary muon beams:  P + X → π  π → μ + ν  10 -2 μ/p → 10 20 μ/year or more

3. 3 Proton Linac (H - )

4. 4 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

5. 5   A  e  A experiments  Next generation of   A  e  A experiments has been proposed  MECO – based at BNL  PRISM-PRIME – based at KEK/JHF  Neither experiment is fully funded  Could either (or both) be hosted at FNAL proton driver ?   A  e  A produces monoenergetic e - (~105MeV)

6. 6 100 300 100 300 GeV Past and future LFV limits SUSY predictions of   A  e - A MECO single event sensitivity 10 -11 10 -13 10 -15 10 -19 10 -17 10 -21 PRIME single event sensitivity 10 -11 10 -13 10 – 5 From Barbieri, Hall, Hisano …

7. 7 MECO layout 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

8. 8 PRISM-PRIME (Y. Kuno et al.) High intensity pulsed proton beam (bunch length <10ns) 100-1000Hz bunches Pion capture solenoid & decay Phase rotation with rf field Δp/p : ±30%  3% Similar to the front end of the neutrino factory

9. 9 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, 1.5  10 -3 captured μ’s/proton  ~6  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)  Both require pulsed beams, proton linac beam must be repackaged in an accumulator ring

10. 10 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

11. 11 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  Reduce N to 0.4  10 13 → δν = 0.1  PRISM/PRIME 10ns bunches, 100/ring  B F = 0.1 → δν =1.2: too large (but closer)  Larger ε N, smaller N tot,  Smaller circumference ring would be better

12. 12 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)

13. 13 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

14. 14 Other potential proton storage schemes  Accumulator or Debuncher (C= ~454m) after 2010…  Large aperture machines  Difficult to inject H - (must bend beam from Linac) (B ~600m)  Could take debunched protons from Recycler or Main Injector(in ~450m chunks)  Or Old linac + Booster  Bunch into pattern needed for experiments  Bunching easier than Recycler  Better match for MECO

15. 15 Detailed  source design does not exist Straw man design worked out for the front end of a factory supported by MARS simulations (Ray et al.) Target + capture solenoid + drift (forward capture) 1.4 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

16. 16 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  MECO  ‘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

17. 17 Summary  Muon Beams from the Proton Driver could be very useful  Potential muon beam facilities could be developed:  MECO, PRISM … could be hosted  More Detailed design needed  Proton Collection –Recycler, Accumulator, Debuncher, … –New Stretcher/Buncher ring ??  Beam line(s)  Experimental area(s)

18. 18 Proton Driver Parameters 8 GeV LINAC EnergyGeV8 Particle Type H- Ions, Protons, or Electrons Rep. RateHz10 Active Lengthm671 Beam CurrentmA25 Pulse Lengthmsec1 Beam IntensityP / pulse1.5E+14 (can also be H-, P, or e-) P/s1.5E+15 Linac Beam PowerMW avg.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