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

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)

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!).

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)

Pion Momentum

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.

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)

Target in the PS

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

Negative muon y-z distribution

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

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

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

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

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

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!

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

Pitch angle for pions and muons TS DS TS

Pitch angle vs Rm Rm [cm] Pions Muons

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.

Simulated Trajectories in PS & TS

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

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

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

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

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

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

Muon hits : Circular foils Muon energy loss [MeV]

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

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

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

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

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

Stopping efficiency for 10,000 muons (Tumakov’s) for same volume target GeometryStopped muonsHit but not stopped Circular foils Single cone Multiple cones (40 o -80 o ) 60 o

Spectrometer Performance Calculations FWHM ~900 keV  Aiming for ~200 KeV/c resolution

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

Signal and DIO from the proposal 0.8MeV

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

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

70 o 50 o 40 o 80 o

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