1. 30 March 20041 Global Mice Particle Identification Steve Kahn 30 March 2004 Mice Collaboration Meeting

2. Steve Kahn 30 March 2004Particle Identification Page 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.

3. Steve Kahn 30 March 2004Particle Identification Page 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.

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5. Steve Kahn 30 March 2004Particle Identification Page 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. =37.6 ns.   T =176 ps The  T corresponds well to what we expect for  with P=200 MeV 37.6 ns. Obsolete

6. Steve Kahn 30 March 2004Particle Identification Page 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.

7. Steve Kahn 30 March 2004Particle Identification Page 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.

8. Steve Kahn 30 March 2004Particle Identification Page 8 The Upstream Cherenkov : Ckov1 C 6 F 13 Radiator C L MIR ROR C 6 F 1 4 P M T UV WIN DO W beam mirror PMT 0 20 40 60 80 100 Npe e  Candidates 186MeV/c1cm C6F14 The figure shows clean separation of 186 MeV/c e, , . However at 250 MeV/c we should expect significant overlap between  and .

9. Steve Kahn 30 March 2004Particle Identification Page 9 Ckov1 Parameters and Status Status: we now see hits and digits for Ckov1. Radiator is C 6 F 14 with n refr =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.

10. Steve Kahn 30 March 2004Particle Identification Page 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.

11. Steve Kahn 30 March 2004Particle Identification Page 11 Electrons from Muon Decay are Present in the Downstream Track Sample ~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 Angular Distribution Spacial Distribution

12. Steve Kahn 30 March 2004Particle Identification Page 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.

13. Steve Kahn 30 March 2004Particle Identification Page 13 Downstream Cherenkov Ckov2 is a threshold Cherenkov The refraction index is n refr =1.02 This corresponds to p  >525 MeV/c for muons But only p e >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

14. Steve Kahn 30 March 2004Particle Identification Page 14 The Muon Beam Expands as the Field Falls Off The calorimeter subtends 60  60 cm

15. Steve Kahn 30 March 2004Particle Identification Page 15 Muon vs electron identification in EMcal 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 cm 2, 3.25x3.25 cm 2, 2.5x2.5 cm 2, 2.5x4.0 cm 2 We only consider a “pattern- based” identification algorithm, i.e. detection efficiency in layers >1 Stolen from A. Tonazzo

16. Steve Kahn 30 March 2004Particle Identification Page 16 Calorimeter signal, efficiency definition Detection efficiency is defined by a cut on signal above noise threshold: 3-4 p.e. PMT signalEnergy deposit “ digitization”: Light attenuation along fibers Winston cone collection efficiency Photocatode quantum efficiency Stolen from A. Tonazzo

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19. Steve Kahn 30 March 2004Particle Identification Page 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.

20. Steve Kahn 30 March 2004Particle Identification Page 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

21. Steve Kahn 30 March 2004Particle Identification Page 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.