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)

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

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 < Polarization >50% Anomalous magnetic moment ⇒ 3σ deviation (exp. & SM) New experiment （ 0.1ppm ）

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

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

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

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]

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

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

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)

Single track finding Hough transform is used. Flow chart

Event display

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

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.

Answer (6 signal tracks) 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.

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.

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