From 9813b4b2794c52a6b5e2619e6178c6b10a8a4f42 Mon Sep 17 00:00:00 2001
From: epic-capybara <139920704+epic-capybara@users.noreply.github.com>
Date: Wed, 16 Oct 2024 18:03:16 -0400
Subject: [PATCH] [Backport v1.18] Fix RP reco bug in p_y (#1636)

# Description
Backport of #1634 to `v1.18`.

Co-authored-by: Alex Jentsch <alexmichaeljentsch@gmail.com>
---
 .../fardetectors/MatrixTransferStatic.cc      | 36 ++++++++++---------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/src/algorithms/fardetectors/MatrixTransferStatic.cc b/src/algorithms/fardetectors/MatrixTransferStatic.cc
index 48331e6c67..01b933806a 100644
--- a/src/algorithms/fardetectors/MatrixTransferStatic.cc
+++ b/src/algorithms/fardetectors/MatrixTransferStatic.cc
@@ -81,10 +81,10 @@ void eicrecon::MatrixTransferStatic::process(
      aY[1][0] = 0.0204108951; //c
      aY[1][1] = -0.139318692; //d
 
-     local_x_offset       = -0.339334;
-     local_y_offset       = -0.000299454;
-     local_x_slope_offset = -0.219603248;
-     local_y_slope_offset = -0.000176128;
+     local_x_offset       = -1209.29;//-0.339334; these are the local coordinate values
+     local_y_offset       = 0.00132511;//-0.000299454;
+     local_x_slope_offset = -45.4772;//-0.219603248;
+     local_y_slope_offset = 0.000745498;//-0.000176128;
 
   }
   else if(abs(100.0 - nomMomentum)/100.0 < nomMomentumError){
@@ -99,10 +99,10 @@ void eicrecon::MatrixTransferStatic::process(
      aY[1][0] = 0.0226283320; //c
      aY[1][1] = -0.082666019; //d
 
-     local_x_offset       = -0.329072;
-     local_y_offset       = -0.00028343;
-     local_x_slope_offset = -0.218525084;
-     local_y_slope_offset = -0.00015321;
+     local_x_offset       = -1209.27;//-0.329072;
+     local_y_offset       = 0.00355218;//-0.00028343;
+     local_x_slope_offset = -45.4737;//-0.218525084;
+     local_y_slope_offset = 0.00204394;//-0.00015321;
 
   }
   else if(abs(41.0 - nomMomentum)/41.0 < nomMomentumError){
@@ -117,10 +117,10 @@ void eicrecon::MatrixTransferStatic::process(
          aY[1][0] = 0.0179664765; //c
          aY[1][1] = 0.004160679; //d
 
-         local_x_offset       = -0.283273;
-         local_y_offset       = -0.00552451;
-         local_x_slope_offset = -0.21174031;
-         local_y_slope_offset = -0.003212011;
+         local_x_offset       = -1209.22;//-0.283273;
+         local_y_offset       = 0.00868737;//-0.00552451;
+         local_x_slope_offset = -45.4641;//-0.21174031;
+         local_y_slope_offset = 0.00498786;//-0.003212011;
 
   }
   else if(abs(135.0 - nomMomentum)/135.0 < nomMomentumError){ //135 GeV deuterons
@@ -202,16 +202,16 @@ void eicrecon::MatrixTransferStatic::process(
 
     if(!goodHit2 && gpos.z() > m_cfg.hit2minZ && gpos.z() < m_cfg.hit2maxZ){
 
-      goodHit[1].x = pos0.x();
-      goodHit[1].y = pos0.y();
-      goodHit[1].z = gpos.z();
+      goodHit[1].x = gpos.x(); //pos0.x() - pos0 is local coordinates, gpos is global
+      goodHit[1].y = gpos.y(); //pos0.y() - temporarily changing to global to solve the local coordinate issue
+      goodHit[1].z = gpos.z(); //         - which is unique to the Roman pots situation
       goodHit2 = true;
 
     }
     if(!goodHit1 && gpos.z() > m_cfg.hit1minZ && gpos.z() < m_cfg.hit1maxZ){
 
-      goodHit[0].x = pos0.x();
-      goodHit[0].y = pos0.y();
+      goodHit[0].x = gpos.x(); //pos0.x()
+      goodHit[0].y = gpos.y(); //pos0.y()
       goodHit[0].z = gpos.z();
       goodHit1 = true;
 
@@ -252,6 +252,8 @@ void eicrecon::MatrixTransferStatic::process(
         }
       }
 
+          Yip[1] = Yrp[0]/aY[0][1];
+
       // convert polar angles to radians
       double rsx = Xip[1] * dd4hep::mrad;
       double rsy = Yip[1] * dd4hep::mrad;