From d6eca3fd318a52005ebdd1bd4230bde5e257aaa0 Mon Sep 17 00:00:00 2001
From: natochii <natochii@hawaii.edu>
Date: Sun, 21 Apr 2024 22:04:29 +0900
Subject: [PATCH] Added an upstream lepton-hadron joint between the backward
 and ip beam pipes

---
 compact/central_beampipe.xml | 29 ++++++++++++++++++++++++++---
 src/IP6BeamPipe.cpp          | 14 +++++++++++---
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/compact/central_beampipe.xml b/compact/central_beampipe.xml
index 5429d142c..ab3370e70 100644
--- a/compact/central_beampipe.xml
+++ b/compact/central_beampipe.xml
@@ -26,9 +26,12 @@
     <constant name="LeptonIncomingBeampipe_ID3" value="43.00 * mm"/>
     <constant name="LeptonIncomingBeampipe_ID4" value="54.00 * mm"/>
 
-    <!-- lepton lepton outgoing beam pipe -->
+    <!-- upstream lepton-hadron beam pipe joint -->
+    <constant name="UpstreamLeptonHadronBeampipeJointLength" value="20.1 * mm"/>
+
+    <!-- lepton outgoing beam pipe -->
     <constant name="LeptonOutgoingBeampipeThickness" value="2.00 * mm"/>
-    <constant name="LeptonOutgoingBeampipe_z1" value="BeampipeUpstreamStraightLength"/>
+    <constant name="LeptonOutgoingBeampipe_z1" value="BeampipeUpstreamStraightLength + UpstreamLeptonHadronBeampipeJointLength"/>
     <constant name="LeptonOutgoingBeampipe_z2" value="5000.00 * mm"/>
 
     <constant name="LeptonOutgoingBeampipe_ID1" value="62.00 * mm"/>
@@ -42,7 +45,7 @@
     <constant name="HadronIncomingBeampipe_ID3" value="41.15 * mm"/>
 
     <constant name="HadronIncomingBeampipe_z1"
-              value="BeampipeUpstreamStraightLength + 0.5 * max(BeampipeOD,HadronIncomingBeampipe_ID1 + 2* HadronIncomingBeampipeThickness + 2* BeampipeCoatingThickness) * tan(abs(CrossingAngle))"/>
+              value="BeampipeUpstreamStraightLength + UpstreamLeptonHadronBeampipeJointLength + 0.5 * max(BeampipeOD,HadronIncomingBeampipe_ID1 + 2* HadronIncomingBeampipeThickness + 2* BeampipeCoatingThickness) * tan(abs(CrossingAngle))"/>
     <constant name="HadronIncomingBeampipe_z2" value="2690.95 * mm"/>
     <constant name="HadronIncomingBeampipe_z3" value="2890.35 * mm"/>
     <constant name="HadronIncomingBeampipe_z4" value="2940.35 * mm"/>
@@ -85,6 +88,26 @@
       <comment> For upstream beampipe, we subtract the vacuum from the matter </comment>
       <upstream reflect="true"
                 place_vacuum="true">
+        <upstream_lepton_hadron_joint thickness="LeptonOutgoingBeampipeThickness">
+          <vacuum>
+            <zplane z="LeptonOutgoingBeampipe_z1 - UpstreamLeptonHadronBeampipeJointLength" 
+                    OD="LeptonOutgoingBeampipe_ID1"/>
+            <zplane z="LeptonOutgoingBeampipe_z1" 
+                    OD="LeptonOutgoingBeampipe_ID1"/>
+          </vacuum>
+          <coating>
+            <zplane z="LeptonOutgoingBeampipe_z1 - UpstreamLeptonHadronBeampipeJointLength" 
+                    OD="LeptonOutgoingBeampipe_ID1 + 2*BeampipeCoatingThickness"/>
+            <zplane z="LeptonOutgoingBeampipe_z1" 
+                    OD="LeptonOutgoingBeampipe_ID1 + 2*BeampipeCoatingThickness"/>
+          </coating>
+          <matter>
+            <zplane z="LeptonOutgoingBeampipe_z1 - UpstreamLeptonHadronBeampipeJointLength"
+                    OD="LeptonOutgoingBeampipe_ID1 + 2* LeptonOutgoingBeampipeThickness + 2*BeampipeCoatingThickness"/>
+            <zplane z="LeptonOutgoingBeampipe_z1"
+                    OD="LeptonOutgoingBeampipe_ID1 + 6* LeptonOutgoingBeampipeThickness + 2*BeampipeCoatingThickness"/>
+          </matter>
+        </upstream_lepton_hadron_joint>
         <outgoing_lepton thickness="LeptonOutgoingBeampipeThickness">
           <vacuum>
             <zplane z="LeptonOutgoingBeampipe_z1" OD="LeptonOutgoingBeampipe_ID1"/>
diff --git a/src/IP6BeamPipe.cpp b/src/IP6BeamPipe.cpp
index a6a44ff70..55f118f49 100644
--- a/src/IP6BeamPipe.cpp
+++ b/src/IP6BeamPipe.cpp
@@ -204,7 +204,7 @@ static Ref_t create_detector(Detector& det, xml_h e, SensitiveDetector /* sens *
     auto tf = Transform3D(Position(0, 0, axis_intersection));
     if(name == "upstream")
       tf *= Transform3D(RotationY( crossing_angle));
-    else
+    else if(name == "downstream")
       tf *= Transform3D(RotationY( std::abs(crossing_angle)));
     tf *= Transform3D(Position(0, 0, -axis_intersection));
 
@@ -213,7 +213,7 @@ static Ref_t create_detector(Detector& det, xml_h e, SensitiveDetector /* sens *
     BooleanSolid coating;
     BooleanSolid vacuum;
 
-    if (name == "upstream") {
+    if (name == "upstream" || name == "joint") {
       // union of all matter, coating, and vacuum
       UnionSolid matter_union(  std::get<0>(pipe1_polycones), std::get<0>(pipe2_polycones), tf);
       UnionSolid coating_union( std::get<1>(pipe1_polycones), std::get<1>(pipe2_polycones), tf);
@@ -373,11 +373,15 @@ static Ref_t create_detector(Detector& det, xml_h e, SensitiveDetector /* sens *
   xml::Component upstream_c        = x_det.child(_Unicode(upstream));
   xml::Component incoming_hadron_c = upstream_c.child(_Unicode(incoming_hadron));
   xml::Component outgoing_lepton_c = upstream_c.child(_Unicode(outgoing_lepton));
+  xml::Component upstream_lepton_hadron_c = upstream_c.child(_Unicode(upstream_lepton_hadron_joint));
   xml_coll_t     additional_subtractions_upstream(upstream_c, _Unicode(additional_subtraction));
 
   auto volumes_upstream = create_volumes(
     "upstream", outgoing_lepton_c, incoming_hadron_c,additional_subtractions_upstream);
 
+  auto joint_upstream = create_volumes(
+    "joint", upstream_lepton_hadron_c, upstream_lepton_hadron_c,additional_subtractions_upstream);
+
   // reflect
   auto tf_upstream = Transform3D(RotationZYX(0, 0, 0));
   if (getAttrOrDefault<bool>(upstream_c, _Unicode(reflect), true))
@@ -385,11 +389,15 @@ static Ref_t create_detector(Detector& det, xml_h e, SensitiveDetector /* sens *
 
   // add matter
   assembly.placeVolume(std::get<0>(volumes_upstream), tf_upstream);
+  assembly.placeVolume(std::get<0>(joint_upstream), tf_upstream);
   // add coating
   assembly.placeVolume(std::get<1>(volumes_upstream), tf_upstream);
+  assembly.placeVolume(std::get<1>(joint_upstream), tf_upstream);
   // add vacuum
-  if (getAttrOrDefault<bool>(upstream_c, _Unicode(place_vacuum), true))
+  if (getAttrOrDefault<bool>(upstream_c, _Unicode(place_vacuum), true)) {
     assembly.placeVolume(std::get<2>(volumes_upstream), tf_upstream);
+    assembly.placeVolume(std::get<2>(joint_upstream), tf_upstream);
+  }
 
   // -----------------------------
   // Downstream: