1. Mu to e Meeting BNL, 11-12 June 2006 Extinction requirement relaxation (Kevin O’Sullivan) Stopping Target Geometry (Cenap Ozben, David Morse) Yannis Semertzidis BNL Less Pions (Extinction) More Muons

2. Winning Strategy: hit the ground running… Use AGS to provide high proton Intensity with correct timing (relax extinction and high intensity requirements) Use FFAG (YK, et al) Re-evaluate B-field solenoid requirements (spec them based on physics requirements)

3. Winning Strategy: hit the ground running… Use current AGS capabilities (no upgrades) to provide high proton Intensity with correct timing (relax extinction and high intensity requirements, i.e. task is mostly finished!).

4. Winning Strategy: hit the ground running… Use FFAG (YK, et al), to get rid of the pions and greatly improve the muon intensity at the correct momentum by phase rotation. This also relaxes the solenoid field requirements. Re-evaluate B-field solenoid requirements (relax them based on physics)

5. Pion Momentum

6. Winning Strategy: hit the ground running… Overall: work for a year to produce a proposal. It may be possible to reduce the cost to  $30M for the whole experimental apparatus.

7. Extinction Primary particles are generated in the target: Sharp source Muons are produced from pions: Diffused source Different pitch angles and momentum distribution (Phase Space)

8. Target in the PS

9. Production Target Pion source Muon source Pion helix in B-field Muon helix in B-field

10. Negative muon y-z distribution

11. Muon Y, X distribution at entrance of T.S. (Tumakov’s muons) X [cm] Y [cm]

12. Pion Y, X distribution at entrance of T.S. (Tumakov’s pions) X [cm] Y [cm]

13. What is the minimum distance (Rm) of the circle from center? Rm

14. Minimum distance of pion and muon circles from center Rm[cm] Pions Muons

15. Minimum distance of pion and muon circles from center Rm [cm] Pions Muons

16. Pion minimum distance from center in the Y, X plane X [cm] Y [cm] The target is 20cm long and slanted by ~10 o, i.e. dx~3cm!

17. Muon minimum distance from center in the Y, X plane X [cm] Y [cm]

18. Pitch angle for pions and muons Pions @ TS Muons @ DS Muons @ TS

19. Pitch angle vs Rm Rm [cm] Pions Muons

20. Muon Y, X distribution at the entrance of D.S. X [cm] Y [cm] Negative muon losses due to vertical drift. We will study different ways of losing the positive charges (helix in opposite way) with less drift and different collimator geometries.

21. Simulated Trajectories in PS & TS

22. Summary (Extinction) The pion source is sharp, as opposed to the muon source Take advantage of the different phase space of muons and pions, electrons, anti-protons, etc “The Plug” promises to reduce the extinction requirements by at least ~10 2 We further need to 1.Optimize the number and geometry of the Plugs 2.Study different collimator geometries 3.Estimate the plug efficiency

23. Visited BNL for three months, until end of May Plus David Morse, Summer student

24. Present Target Geometry 17 circular foils, 0.2mm thick each 80cm

25. Muon Stopping Target Increase muon stopping power Minimize energy loss for 105MeV electrons and better the collection efficiency

26. Considered Various Geometries: Original (default) geometry of circular foils

27. Non-stop muons: Circular foils Muon energy loss [MeV] Muon energy before and after the target [MeV]

28. Muon hits : Circular foils Muon energy loss [MeV]

29. Stopped muons: Circular foils Muon energy loss [MeV] Muon energy before the target [MeV] muons electrons

30. Stopped muons: Single cone geometry Muon energy loss [MeV] Muon energy before the target [MeV] 11.5 o

31. Stopped muons: Multi cone geometry Muon energy loss [MeV] Muon energy before the target [MeV] 40 o

32. Stopped muons: Multi cone geometry Muon energy loss [MeV] Muon energy before the target [MeV] 80 o

33. Stopped muons: Multi cone geometry Muon energy loss [MeV] Muon energy before the target [MeV] 40 o

34. Stopping efficiency for 10,000 muons (Tumakov’s) for same volume target GeometryStopped muonsHit but not stopped Circular foils22625026 Single cone27053750 Multiple cones (40 o -80 o ) 60 o 2700-3000 2850 4600-4300 4480

35. Spectrometer Performance Calculations FWHM ~900 keV  10 1.0 0.1 0.01 103 104 105 106 Aiming for ~200 KeV/c resolution

36. How do 105 MeV electrons fair? Circular foils FWHM: 0.79MeV

37. Signal and DIO from the proposal 0.8MeV

38. How do 105 MeV electrons fair? Single cone FWHM: 0.85MeV

39. How do 105 MeV electrons fair? Multi cone best FWHM: 0.61MeV 60 o

40. 70 o 50 o 40 o 80 o

41. Summary GEANT3 installed on BNL computers with both Rashid’s and Vladimir’s codes. Have studied a few geometries including the current circular foils. Preliminary results: multi-cones with 60 o -70 o is best:  25% more muons stopped, with less energy loss for 105MeV electrons and better collect. effic. We further need to 1.Finish the study 2.Study new geometries, to take advantage of the e - pitch 3.Include target supports for background estimation