1. Retrieve stereo hits in Hough tracking

2. Tracking efficiency status When |cos|>0.8, efficiency drop fast (1) (2) Figure(1) efficiency : events found at least 1 track/all events Figure(2) efficiency : events found at least 1 track past track quality/all events Track quality cut: |Δpt|<10MeV |Δp |<15MeV |Δvr|<1cm |Δvz|<10cm

3. Method to get back lost hit when large |cos| Use 2d circle information after 2d fit Calculate distance of every stereo hit position to the 2d circle(mid point position) Use drift information to help to reject noise hit Retrieve lost stereo hits inside a certain distance cut and reject noise hits

4. Some Explain Aim to deal with stereo hits when |cos|>0.8 to adjust the bin cut in Hough Map Cause this is used to retrieve lost hits, use a strict condition to reject noise hits Sensitive to multi turn tracks, so want it only for |cos|>0.8 When |cos|>0.8 peak width get larger,so lost more stereo hits

5. Layer <8 (drift distance cut) signal stereo hit drift distanceNoise stereo hit drift distance When cut at drift distance 0.6, cut more noise stereo hits (cm)

6. Layer<8 (distance to circle) signal stereo hit distance to circlenoise stereo hit distance to circle Next try different cut to get more signal hits and reject noise hits (cm)

7. Layer<8 (distance to circle cut) proportion of signal hit/all hits vary with different cut Number of signal hits vary with different cut We want high signal rate and more signal hits use cut distance=3.0 cm,means when distance of a stereo hits to circle<3.0cm, retrieve the hit rate Signal hits (cm)

8. Layer>=8(drift distance cut) When cut at drift distance 0.8, cut more noise stereo hits Noise stereo hit drift distancesignal stereo hit drift distance (cm)

9. Layer>=8 (distance to circle) Next try different cut to get more signal hits and reject noise hits signal stereo hit distance to circlenoise stereo hit distance to circle (cm)

10. Layer<8 (distance to circle cut) use cut distance=4.0 cm proportion of signal hit/all hits vary with different cut Number of signal hits vary with different cut (cm)

11. Tracking efficiency status Track quality cut: |Δpt|<10MeV |Δp |<15MeV |Δvr|<1cm |Δvz|<10cm events found at least 1 track/all events Add quality cut After get back lost hits before get back lost hits Tracking efficiency upgrate ~15% when |cos|>0.8 Influence on multi turn tracks when |cos| is small

12. Hit number on track before get back lost hits After get back lost hits |Cos|>0.8 After this method, signal hits number on track increase Noise ghost track decline