From d1991ea22dd2068dd50dce908be39729e77c93b0 Mon Sep 17 00:00:00 2001
From: John Stupak <john.stupak@cern.ch>
Date: Sat, 4 Apr 2020 00:24:36 +0000
Subject: [PATCH] Improved IP calculation
---
.../src/SiSpacePointsSeedMaker_ATLxk.cxx | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/InnerDetector/InDetRecTools/SiSpacePointsSeedTool_xk/src/SiSpacePointsSeedMaker_ATLxk.cxx b/InnerDetector/InDetRecTools/SiSpacePointsSeedTool_xk/src/SiSpacePointsSeedMaker_ATLxk.cxx
index 20e6fe8943d..41606fdf812 100644
--- a/InnerDetector/InDetRecTools/SiSpacePointsSeedTool_xk/src/SiSpacePointsSeedMaker_ATLxk.cxx
+++ b/InnerDetector/InDetRecTools/SiSpacePointsSeedTool_xk/src/SiSpacePointsSeedMaker_ATLxk.cxx
@@ -1439,7 +1439,11 @@ void InDet::SiSpacePointsSeedMaker_ATLxk::production3Sp
float B2 = B*B;
if (B2 > ipt2K*S2 || dT*S2 > B2*CSA) continue;
- float Im = fabs((A-B*R)*R);
+ float y0=1./(2*B);
+ float x0=-A*y0;
+ float rTrack = sqrt(S2/B2)/2 ;
+ float Im = fabs(-rTrack + sqrt(rTrack*rTrack +2*x0*R +R*R));
+
if (Im <= imax) {
float dr = data.R[b];
--
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