Global Mice Particle Identification

1. Global Mice Particle Identification Steve Kahn 30 March 2004 Mice Collaboration Meeting

2. Particle ID Elements • Upstream Detectors: • Time of Flight system • Rely on the time difference between stations TOF0and TOF1 to provide velocity measurement. • Upstream Cherenkov System • Verifies that the track is a muon. • Downstream Detectors: • Time of Flight system • Verifies the existence and its time for a track exiting the detector solenoid. Particle Identification

3. Particle ID Elements • Downstream Detectors (cont.) • Downstream Cherenkov System • Verifies that the track seen in TOF2 is an electron. • Not sensitive to muons. • EM Calorimeter • Shows whether a track that is seen in TOF2 has an EM shower or not. • Tracking Systems • Needed to know the particle momentum. Particle Identification

4. Particle Identification

5. Upstream TOF System • Plots on the right show: • Upper plot shows time distributions at TOF0 and TOF1: • T=30 ns for these stations. • Lower plot shows the transit time of individual  tracks. • <T>=37.6 ns. • T=176 ps • The T corresponds well to what we expect for  with P=200 MeV • 37.6 ns. Obsolete Particle Identification

6. Separating  from  in the Real World • Tom Roberts has shown an analysis using the Tof timing along with the momentum from the tracker to separate  from . • Tof information is not sufficient by itself since there is some overlap in the  and  velocity distributions. • There are 17  in the lower plot; 5 of the  overlap the  distribution. Particle Identification

7. Requirements for ToF Particle ID • The TofParticleID class will need: • Access to TOF0 and TOF1 digitizations for the same event (actually for the same track). • Our ROOT structure keeps digitizations separate. • Knowledge of the Tracker reconstructed momentum. • All of the TOF0 hits in the pile-up time interval • We need to estimate the likelihood that a time coincidence is real or coincidental. Particle Identification

8. e-m-p Candidates 186MeV/c 1cm C6F14 PMT UV WINDOW MIRROR CL 0 20 40 60 80 100 Npe C6F14 The Upstream Cherenkov : Ckov1 C6F13 Radiator PMT mirror beam The figure shows clean separation of 186 MeV/c e, ,. However at 250 MeV/c we should expect significant overlap between  and . Particle Identification

9. Ckov1 Parameters and Status • Status: we now see hits and digits for Ckov1. • Radiator is C6F14 with nrefr=1.25 • Thresholds are 0.7 (e), 140 () and 190() MeV/c respectively. • The Ckov1 alone will not be able to distinguish  from  since the velocities are close as we have seen. • The discrimination comes from the pulse height analysis, where the (dE/dx)Č is largely a function of  alone. • With the knowledge of the momentum from the tracker we should be able to separate  from . • The Ckov1 may be less sensitive to the background than TOF since TOF I is located in a position with lots of background. Particle Identification

10. Ckov1 Particle ID Software Needs • The Ckov1 acts independent of the other particle ID detectors. • Since it has a single PMT it cannot measure the radius of the Cherenkov cone. • It will only measure a pulse height. • It will need to know the momentum from the tracker reconstruction. Particle Identification

11. Electrons from Muon Decay are Present in the Downstream Track Sample Angular Distribution ~1% of downstream tracks may be electrons, not muons. 80% of these electrons can be removed by kinematics, but this could bias the emittance measurement Momentum Distribution Spacial Distribution Particle Identification

12. Downstream Detectors • The figure on the right shows the placement of the downstream detectors. • Both the Ckov2 and EMcal need a coincidence with the TOF III. Particle Identification

13. Downstream Cherenkov • Ckov2 is a threshold Cherenkov • The refraction index is nrefr=1.02 • This corresponds to p>525 MeV/c for muons • But only pe>2.5 MeV/c for electrons • If we see a signal in Ckov2 and TOF III it is EM energy • Single ionizing electron • Twice minimum ionizing photon Particle Identification

14. The Muon Beam Expands as the Field Falls Off The calorimeter subtends 6060 cm Particle Identification

15. Muon vs electron identification in EMcal We only consider a “pattern-based” identification algorithm, i.e. detection efficiency in layers >1 We have carried out simulation studies in G4MICE to optimize the mu/electron separation capabilities by varying: • sampling fraction, i.e. lead layer thickness: 0.5-0.2 mm • readout segmentation, i.e. cell size: 3.75x3.75 cm2, 3.25x3.25 cm2, 2.5x2.5 cm2, 2.5x4.0 cm2 Stolen from A. Tonazzo Particle Identification

16. Calorimeter signal, efficiency definition Energy deposit PMT signal “digitization”: • Light attenuation along fibers • Winston cone collection efficiency • Photocatode quantum efficiency Detection efficiency is defined by a cut on signal above noise threshold: 3-4 p.e. Stolen from A. Tonazzo Particle Identification

17. Particle Identification

18. Particle Identification

19. Software Requirements of Particle ID • Common Requirements: • Need to access information from more than one detector unit: • Upstream TOF requires two stations • Downstream Ckov2 or Emcal also require TOF2 • Need results of Tracker reconstruction. • Primarily the track momentum and error. • Need to create an Event class that contains: • All detector results • Digitizations for particle ID detectors • Reconstruction for tracker detectors. • We are currently not organized that way. Particle Identification

20. Particle ID Classes • There should be a ParticleID class for each ParticleID algorithm. • There may be one or more than one way to handle the information from each particleID detector system. • Each of these ParticleID classes should inherit from a ParticleIDBase class Particle Identification

21. ParticleIDBase class • Contain common quantities. • Should contain: • Detector/Algorithm identification • Reconstructed P, P from tracker for track. • Link to reconstructed track. • Probabilities of being ,,,e. • Quality factor from algorithm determination. Particle Identification