From a8c77be2180bdff3b586beeea351f6542ac2b864 Mon Sep 17 00:00:00 2001
From: Matt Posik <mposik1983@gmail.com>
Date: Thu, 26 Sep 2024 04:52:26 -0400
Subject: [PATCH] Mpgd gas mix (#784)

### Briefly, what does this PR introduce?
Change the gas mixture in the outer barrel and end cap MPGDs

### What kind of change does this PR introduce?
- [ ] Bug fix (issue #__)
- [ ] New feature (issue #__)
- [ ] Documentation update
- [ x] Other: __

### Please check if this PR fulfills the following:
- [ ] Tests for the changes have been added
- [ ] Documentation has been added / updated
- [ x] Changes have been communicated to collaborators

### Does this PR introduce breaking changes? What changes might users
need to make to their code?
No. None
### Does this PR change default behavior?
Gas mixture change will lead to slightly different deposited energy
distribution in the outer barrel and end cap MPGDs

---------

Co-authored-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
---
 compact/materials.xml                         |  2 +-
 .../tracking/central_tracker_hybrid_v2.xml    | 48 +++++++++----------
 .../deprecated/gem_tracker_endcap.xml         | 24 +++++-----
 compact/tracking/mpgd_backward_endcap.xml     |  8 ++--
 compact/tracking/mpgd_forward_endcap.xml      |  8 ++--
 compact/tracking/mpgd_outerbarrel.xml         |  4 +-
 6 files changed, 47 insertions(+), 47 deletions(-)

diff --git a/compact/materials.xml b/compact/materials.xml
index 95ee8d1a5..fbefb0638 100644
--- a/compact/materials.xml
+++ b/compact/materials.xml
@@ -338,7 +338,7 @@
     <composite n="4" ref="O"/>
     <constant name="BirksConstant" value="0.0333*mm/MeV"/>
   </material>
-  <material name="Ar10CO2">
+  <material name="Ar90CO2">
     <D type="density" value="1.802" unit="mg / cm3"/>
     <composite n="0.891" ref="Argon"/>
     <!--<composite n="0.109" ref="CarbonDioxide"/>-->
diff --git a/compact/tracking/central_tracker_hybrid_v2.xml b/compact/tracking/central_tracker_hybrid_v2.xml
index 64d916fa4..925192edf 100644
--- a/compact/tracking/central_tracker_hybrid_v2.xml
+++ b/compact/tracking/central_tracker_hybrid_v2.xml
@@ -1047,22 +1047,22 @@ total X0 0.24% per disk layer （4 sectors per disk):
         <trd x1="GEMEndcapRingMod_x1/2" x2="GEMEndcapRingMod_x2/2" z="GEMEndcapRingMod_y/2" />
         <comment> going from back to front </comment>
         <module_component name="exit_window"      thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerServiceVis" />
-        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="readout_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="readout_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="gem_foil_3_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_3"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_2_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_2"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_1_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_1"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar10CO2" sensitive="true"/>
+        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar90CO2" sensitive="true"/>
         <module_component name="cathode_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="cathode_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="entrance_window"  thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerMPGDVis" />
       </module>
       <module name="RingBotFrame" vis="TrackerSupportVis">
@@ -1161,22 +1161,22 @@ total X0 0.24% per disk layer （4 sectors per disk):
         <trd x1="GEMEndcapRingMod_x1/2" x2="GEMEndcapRingMod_x2/2" z="GEMEndcapRingMod_y/2" />
         <comment> going from back to front </comment>
         <module_component name="exit_window"      thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerServiceVis" />
-        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="readout_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="readout_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="gem_foil_3_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_3"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_2_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_2"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_1_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_1"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar10CO2" sensitive="true"/>
+        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar90CO2" sensitive="true"/>
         <module_component name="cathode_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="cathode_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="entrance_window"  thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerMPGDVis" />
       </module>
       <module name="RingBotFrame" vis="TrackerSupportVis">
@@ -1195,22 +1195,22 @@ total X0 0.24% per disk layer （4 sectors per disk):
         <trd x1="GEMEndcapLargeMod_x1/2" x2="GEMEndcapLargeMod_x2/2" z="GEMEndcapLargeMod_y/2" />
         <comment> going from back to front </comment>
         <module_component name="exit_window"      thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerServiceVis" />
-        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="readout_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="readout_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="gem_foil_3_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_3"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_2_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_2"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_1_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_1"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar10CO2" sensitive="true"/>
+        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar90CO2" sensitive="true"/>
         <module_component name="cathode_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="cathode_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="entrance_window"  thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerMPGDVis" />
       </module>
       <module name="LargeBotFrame" vis="TrackerSupportVis">
@@ -1309,22 +1309,22 @@ total X0 0.24% per disk layer （4 sectors per disk):
         <trd x1="GEMEndcapLargeMod_x1/2" x2="GEMEndcapLargeMod_x2/2" z="GEMEndcapLargeMod_y/2" />
         <comment> going from back to front </comment>
         <module_component name="exit_window"      thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerServiceVis" />
-        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="exit_region"      thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="readout_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="readout_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="induction_region" thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="gem_foil_3_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_3"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region2" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_2_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_2"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar10CO2"/>
+        <module_component name="transfer_region1" thickness="GEMGas_thickness"                          material="Ar90CO2"/>
         <module_component name="gem_foil_1_cu"    thickness="GEMCuElectrode_thickness * GEMAreaFactor"  material="Copper"/>
         <module_component name="gem_foil_1"       thickness="GEMKapton_thickness * GEMAreaFactor"       material="Kapton"/>
-        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar10CO2" sensitive="true"/>
+        <module_component name="drift_region"     thickness="GEMDriftRegion_thickness"                  material="Ar90CO2" sensitive="true"/>
         <module_component name="cathode_cu"       thickness="GEMCuElectrode_thickness"  material="Copper"/>
         <module_component name="cathode_foil"     thickness="GEMKapton_thickness"       material="Kapton"/>
-        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar10CO2"/>
+        <module_component name="entrance_region"  thickness="GEMGas_thickness"          material="Ar90CO2"/>
         <module_component name="entrance_window"  thickness="GEMMylar_thickness"        material="Mylar" vis="TrackerMPGDVis" />
       </module>
       <module name="LargeBotFrame" vis="TrackerSupportVis">
diff --git a/compact/tracking/deprecated/gem_tracker_endcap.xml b/compact/tracking/deprecated/gem_tracker_endcap.xml
index 71df2d13e..f3a0b1e96 100644
--- a/compact/tracking/deprecated/gem_tracker_endcap.xml
+++ b/compact/tracking/deprecated/gem_tracker_endcap.xml
@@ -113,22 +113,22 @@
         </comment>
         <comment> Going from HV side to readout side</comment>
               <module_component thickness="25.0*um" material="Mylar" name="entrance_window" vis="TrackerLayerVis"/>
-              <module_component thickness=" 2.0*mm" material="Ar10CO2" name="entrance_region" />
+              <module_component thickness=" 2.0*mm" material="Ar90CO2" name="entrance_region" />
         <module_component thickness="50.0*um" material="Kapton" name="cathode_foil"/>
               <module_component thickness=" 5.0*um" material="Copper" name="cathode_cu"/>
-        <module_component thickness=" 3.0*mm" material="Ar10CO2" sensitive="true" name="drift_region" vis="AnlProcess_Blue"/>
+        <module_component thickness=" 3.0*mm" material="Ar90CO2" sensitive="true" name="drift_region" vis="AnlProcess_Blue"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_1"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_1_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="transfer_region_I"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="transfer_region_I"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_2"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_2_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="transfer_region_II"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="transfer_region_II"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_3"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_3_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="induction_region"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="induction_region"/>
         <module_component thickness="50.0*um" material="Kapton"  name="readout_foil"/>
               <module_component thickness=" 5.0*um" material="Copper"  name="readout_cu"/>
-              <module_component thickness=" 2.0*mm" material="Ar10CO2" name="exit_region"/>
+              <module_component thickness=" 2.0*mm" material="Ar90CO2" name="exit_region"/>
         <module_component thickness="25.0*um" material="Mylar" name="exit_window" vis="TrackerLayerVis"/>
       </module>
       <module name="GEMSupportSpokes" vis="TrackerSupportVis">
@@ -177,22 +177,22 @@
         </comment>
         <comment> Going from HV side to readout side</comment>
         <module_component thickness="25.0*um" material="Mylar" name="entrance_window" vis="TrackerLayerVis"/>
-              <module_component thickness=" 2.0*mm" material="Ar10CO2" name="entrance_region" />
+              <module_component thickness=" 2.0*mm" material="Ar90CO2" name="entrance_region" />
         <module_component thickness="50.0*um" material="Kapton" name="cathode_foil"/>
               <module_component thickness=" 5.0*um" material="Copper" name="cathode_cu"/>
-        <module_component thickness=" 3.0*mm" material="Ar10CO2" sensitive="true" name="drift_region" vis="AnlProcess_Blue"/>
+        <module_component thickness=" 3.0*mm" material="Ar90CO2" sensitive="true" name="drift_region" vis="AnlProcess_Blue"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_1"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_1_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="transfer_region_I"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="transfer_region_I"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_2"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_2_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="transfer_region_II"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="transfer_region_II"/>
         <module_component thickness="GEMAreaFactor*50.0*um" material="Kapton"  name="gem_foil_3"/>
         <module_component thickness="GEMAreaFactor*10.0*um" material="Copper"  name="gem_foil_3_cu"/>
-        <module_component thickness=" 2.0*mm" material="Ar10CO2" name="induction_region"/>
+        <module_component thickness=" 2.0*mm" material="Ar90CO2" name="induction_region"/>
         <module_component thickness="50.0*um" material="Kapton"  name="readout_foil"/>
               <module_component thickness=" 5.0*um" material="Copper"  name="readout_cu"/>
-              <module_component thickness=" 2.0*mm" material="Ar10CO2" name="exit_region"/>
+              <module_component thickness=" 2.0*mm" material="Ar90CO2" name="exit_region"/>
         <module_component thickness="25.0*um" material="Mylar" name="exit_window" vis="TrackerLayerVis"/>
       </module>
       <module name="GEMSupportSpokes" vis="TrackerSupportVis">
diff --git a/compact/tracking/mpgd_backward_endcap.xml b/compact/tracking/mpgd_backward_endcap.xml
index e0eb6d668..37f34975e 100644
--- a/compact/tracking/mpgd_backward_endcap.xml
+++ b/compact/tracking/mpgd_backward_endcap.xml
@@ -75,8 +75,8 @@
         <module name="BackwardModule1" vis="MPGDModuleVis">
           <trd x1="BackwardMPGDMod1_x1/2.0" x2="BackwardMPGDMod1_x2/2.0" z="BackwardMPGDMod1_y/2"/>
           <comment> Window and drift region </comment>
-          <module_component thickness="BackwardMPGDDriftGap_thickness" material="Ar" sensitive="true" vis="MPGDVis"/>
-          <module_component thickness="BackwardMPGDWindowGap_thickness" material="Ar" sensitive="false" vis="MPGDVis"/>
+          <module_component thickness="BackwardMPGDDriftGap_thickness" material="Ar90IsoButane" sensitive="true" vis="MPGDVis"/>
+          <module_component thickness="BackwardMPGDWindowGap_thickness" material="Ar90IsoButane" sensitive="false" vis="MPGDVis"/>
           <module_component thickness="BackwardMPGDWindow_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
           <comment> HV Cathode </comment>
           <module_component name="Cathode Kapton" thickness="BackwardMPGDFoilKapton_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
@@ -94,8 +94,8 @@
         <module name="BackwardModule2" vis="MPGDModuleVis">
           <trd x1="BackwardMPGDMod2_x1/2.0" x2="BackwardMPGDMod2_x2/2.0" z="BackwardMPGDMod2_y/2"/>
           <comment> Window and drift region </comment>
-          <module_component thickness="BackwardMPGDDriftGap_thickness" material="Ar" sensitive="true" vis="MPGDVis"/>
-          <module_component thickness="BackwardMPGDWindowGap_thickness" material="Ar" sensitive="false" vis="MPGDVis"/>
+          <module_component thickness="BackwardMPGDDriftGap_thickness" material="Ar90IsoButane" sensitive="true" vis="MPGDVis"/>
+          <module_component thickness="BackwardMPGDWindowGap_thickness" material="Ar90IsoButane" sensitive="false" vis="MPGDVis"/>
           <module_component thickness="BackwardMPGDWindow_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
           <comment> HV Cathode </comment>
           <module_component name="Cathode Kapton" thickness="BackwardMPGDFoilKapton_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
diff --git a/compact/tracking/mpgd_forward_endcap.xml b/compact/tracking/mpgd_forward_endcap.xml
index afd5b0cf2..f36b0fd67 100644
--- a/compact/tracking/mpgd_forward_endcap.xml
+++ b/compact/tracking/mpgd_forward_endcap.xml
@@ -75,8 +75,8 @@
         <module name="ForwardModule1" vis="MPGDModuleVis">
           <trd x1="ForwardMPGDMod1_x1/2.0" x2="ForwardMPGDMod1_x2/2.0" z="ForwardMPGDMod1_y/2"/>
           <comment> Window and drift region </comment>
-          <module_component thickness="ForwardMPGDDriftGap_thickness" material="Ar" sensitive="true" vis="MPGDVis"/>
-          <module_component thickness="ForwardMPGDWindowGap_thickness" material="Ar" sensitive="false" vis="MPGDVis"/>
+          <module_component thickness="ForwardMPGDDriftGap_thickness" material="Ar90IsoButane" sensitive="true" vis="MPGDVis"/>
+          <module_component thickness="ForwardMPGDWindowGap_thickness" material="Ar90IsoButane" sensitive="false" vis="MPGDVis"/>
           <module_component thickness="ForwardMPGDWindow_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
           <comment> HV Cathode </comment>
           <module_component name="Cathode Kapton" thickness="ForwardMPGDFoilKapton_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
@@ -93,8 +93,8 @@
         <module name="ForwardModule2" vis="MPGDModuleVis">
           <trd x1="ForwardMPGDMod2_x1/2.0" x2="ForwardMPGDMod2_x2/2.0" z="ForwardMPGDMod2_y/2"/>
           <comment> Window and drift region </comment>
-          <module_component thickness="ForwardMPGDDriftGap_thickness" material="Ar" sensitive="true" vis="MPGDVis"/>
-          <module_component thickness="ForwardMPGDWindowGap_thickness" material="Ar" sensitive="false" vis="MPGDVis"/>
+          <module_component thickness="ForwardMPGDDriftGap_thickness" material="Ar90IsoButane" sensitive="true" vis="MPGDVis"/>
+          <module_component thickness="ForwardMPGDWindowGap_thickness" material="Ar90IsoButane" sensitive="false" vis="MPGDVis"/>
           <module_component thickness="ForwardMPGDWindow_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
           <comment> HV Cathode </comment>
           <module_component name="Cathode Kapton" thickness="ForwardMPGDFoilKapton_thickness" material="Kapton" sensitive="false" vis="MPGDVis"/>
diff --git a/compact/tracking/mpgd_outerbarrel.xml b/compact/tracking/mpgd_outerbarrel.xml
index c4e69c044..0da410812 100644
--- a/compact/tracking/mpgd_outerbarrel.xml
+++ b/compact/tracking/mpgd_outerbarrel.xml
@@ -59,7 +59,7 @@
     <module name="MPGDOuterBarrelModule" vis="TrackerVis">
 
         <module_component name="DriftGap"
-               material="Ar"
+               material="Ar90IsoButane"
                sensitive="true"
                width="MPGDOuterBarrelModule_width"
                thickness="MPGDOuterBarrelDriftGap_thickness"
@@ -67,7 +67,7 @@
                length="MPGDOuterBarrelModule_length"/>
 
         <module_component name="WindowGasGap"
-               material="Ar"
+               material="Ar90IsoButane"
                sensitive="false"
                width="MPGDOuterBarrelModule_width"
                thickness="MPGDOuterBarrelWindowGap_thickness"