1. Track finding with g-2 silicon tracker 2 nd Workshop on Muon g-2 and EDM in the LHC Era May 5, 2012 Kazuki Ueno (RIKEN)

2. Contents Introduction Silicon vane tracker Simulation & track finding Future plan & summary

3. J-PARC muon g-2/EDM Ultra-slow muon beam 300MeV/c Proton beam Positron tracker Muon strage ring (B=3T) Muonium laser ionization Materials & Life science experimental Facility (MLF) H-Line Ultra-slow μ + beam : 10 6 /sec Momentum: 300 MeV/c (γ = 3) σ(p T )/p < 10 -3 Polarization >50% Anomalous magnetic moment ⇒ 3σ deviation (exp. & SM) New experiment （ 0.1ppm ）

4. Silicon vane tracker measurement of track & time for muon decay positron Detector inside muon storage ring High magnetic field 3 T High event rate > 1 MHz Early-to-late effect(2 order of magnitude decrease during 33  s ） Need to detect positron track from a large number of hits On the basis of this schematic view, optimize detector parameters Silicon vane strip tracker Requirements

5. Strategy Understanding event pattern by Geant4 simulation Construction of track finding/fitting tool (software) Conceptual design Development plan 1 st step – Choose detection technique & method 3 rd step – Determination of detector parameters now 2 nd step – Make tools close to real condition  Feedback from evaluation of test detector  Study of detector response  Adding geometry  Background study  Adjustment of detector parameters  Finalization of detector design

6. Geant4 simulator side viewtop view  Geometry Si vane detector – Vane # : 48,40,32,24,16 – strip pitch : 200  m – thickness : 300  m – Center region ： Lead Tungsten Condition – Magnet field 3 Tesla – Electric field 0 V/m –   : 3 (300 MeV/c) – R  : 333mm – vacuum – Signal event : E p >200MeV

7. Typical hit events t=5-10nst=10-15ns signal(>200MeV): 17 BG : 33 signal(>200MeV): 14 BG : 33 (High rate region) X[mm] Y[mm]

8. How to find “true” tracks  t=5-10ns red: signal(E>200MeV) blue:BG(E<200MeV) Hit pattern in each plane ⇒ ”straight line” shape in  Z- plane ⇒ Use this information XY φZXZrZ φrφX

9. Hit pattern time dependency t=0-40us (every 1us) XYφZ It’s not easy to find track in first time region.

10. Track finding tool Find “true” tracks from a large number of hits. Goal ： Eff.>90% Use of “line” shape in  Z-plane is powerful. But, It’s complicated for finding in t<10us. (Eff.=track finding efficiency) Develop finding tool, step by step 1 st step: Single track finding (for t>10us) 2 nd step: Multi track finding (for t<10us)

11. Single track finding Hough transform is used. Flow chart

12. Event display

13. Track finding efficiency for single track Eff.=97% (E>200MeV) Efficiency = Final event#/All event# It’s reasonable.

14. Multi track finding Apply algorithm for single track to multi track as a first step. Adjust some parameters in finding tool. Add other algorithm in the tool if need.

15. Answer (6 signal tracks) 1 2 3 4 5 6 7 8 Example of multi-track finding Sample event (5us<t) 6,8: 150 MeV < E < 200 MeV Others: E>200 MeV Apply tool Results 5 tracks were found at 1 st try. (Current status) Future Apply this tool to other events.

16. Future work  Adjustment parameters of finding tool  Add other algorithm (Maybe it will be needed for first time region)  Ex ： Z-slice Use information in XY-plane for each z-region  Connect tracks between neighbor tracks Eff.>90% will be achieved.

17. Summary J-PARC muon g-2/EDM experiment Silicon vane tracker Design tracker step by step Simulation & track finding tool Track finding efficiency – Single track : 97% (>200MeV) – Multi track : in progress Track fitting tool -> Next Wilfrid’s talk