TOF Emittance Pion Emittance Measurement with the TOFs? Mark Rayner 11 December 2008

TOF Emittance Complications with a Pion Beam Pion  muon decays –c/  of the pion is 7.8m At 250 MeV/c, =(250/140)*7.8m=13.9m and 35% of the pions decay between TOF0 and TOF1 At 400 MeV/c, =(400/140)*7.8m=22.3m and 30% of the pions decay between TOF0 and TOF1 –Can we identify them based in time of flight? Pion decay –P  * = (M  2 – M  2 )/(2M  ) = 29.9 MeV/c Dipole acceptance –Rectangular distribution width +/-10% So distributions will overlap and time of flight cannot help Can the Cherenkov help? –It can separate muons/pions which decay Before TOF0 Between TOF0 and Ckov? Incident pions Muon rest frameBackward decaying muons Forward decaying muons pE  Tof 8mPEPE  PE  MeV/cMeV nsMeV/cMeVMeV/cMeV nsMeV/cMeV ns Incident pions Muon rest frameBackward decaying muons Forward decaying muons pE  Tof 8mPEPE  PE  MeV/cMeV nsMeV/cMeVMeV/cMeV nsMeV/cMeV ns

TOF Emittance TOF Calibration Requirements for an Emittance Measurement Emittance Measurement Assume Linear Beam Optics Use forthcoming TofEmittance app TofSpacePoints Sufficiently well calibrated TDC between detector planes in TOF 0 and TOF 1 Needed to distinguish multiple hits Use new TofCalibration app Momentum measurement Required for tracking (create ‘TofTracks’) Sufficiently well calibrated TDC between TOF 0 and TOF 1 Assume constant path length Use new TofCalibration app TOF0 to TOF1 calibration Electrons (800cm/30cm)ns between stations Station calibration Electrons (2.5cm/30cm)ns between planes Plane calibration Any beam Use reference slab in other plane Time walk calibration Any beam Pulse by pulse ADC correction to TDC ? ?

TOF Emittance TOF Plane Cable Length TDC Calibration

TOF Emittance Conclusion Q789  /2 optics calculated for 250 MeV/c particles before TOF 0 Will recalculate for 400 MeV/c However an unknown ~35% of the ‘pions’ will have decayed between TOFs Nevertheless important TOF calibration work can be accomplished –<100 MeV/c electrons TOF0  TOF1 calibration Station calibration –Any beam Plane calibration –Investigation into timewalk fADC-TDC correlation not yet understood New apps (TofMonitor and TofCalibration) can help with this g 07 [T/m] T/m g 09 –g 08 TOF0 to TOF1 calibration Electrons (800cm/30cm)ns between stations Station calibration Electrons (2.5cm/30cm)ns between planes Plane calibration Any beam Use reference slab in other plane Time walk calibration Any beam Pulse by pulse ADC correction to TDC