Retrieve stereo hits in Hough tracking

Tracking efficiency status (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 When |cos|>0.8 , efficiency drop fast

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

Some Explain Aim to deal with stereo hits when |cos|>0.8 to adjust the bin cut in Hough Map When |cos|>0.8 peak width get larger ,so lost more stereo hits 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

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

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

Layer<8 (distance to circle cut) proportion of signal hit/all hits vary with different cut Number of signal hits vary with different cut rate Signal hits (cm) (cm) 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

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

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

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

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

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