diff --git a/Simulation/DetSimDedx/src/TrackHeedSimTool.cpp b/Simulation/DetSimDedx/src/TrackHeedSimTool.cpp
index a4fe56c70f84ea3c7b1d27dc97f2d0645ee3db2f..3302887172281028c7f1795ceb14b72e2d5e82c4 100644
--- a/Simulation/DetSimDedx/src/TrackHeedSimTool.cpp
+++ b/Simulation/DetSimDedx/src/TrackHeedSimTool.cpp
@@ -363,7 +363,7 @@ StatusCode TrackHeedSimTool::initialize()
   }
   else if(m_det=="TPC"){
       m_gas.SetTemperature(293.15);
-      m_gas.SetPressure(750.);
+      m_gas.SetPressure(m_gaspressure);
       m_gas.SetComposition("Ar", 95., "isobutane", 2., "CF4", 3.);
   }
 
diff --git a/Simulation/DetSimDedx/src/TrackHeedSimTool.h b/Simulation/DetSimDedx/src/TrackHeedSimTool.h
index eb66b4ed09234dff8a4601165c3e9c01bcf5d818..e2605fa1c585350e1b1023516409b13a4c5ddc7c 100644
--- a/Simulation/DetSimDedx/src/TrackHeedSimTool.h
+++ b/Simulation/DetSimDedx/src/TrackHeedSimTool.h
@@ -90,6 +90,7 @@ class TrackHeedSimTool: public extends<AlgTool, IDedxSimTool> {
         Gaudi::Property<float> m_change_threshold {this, "change_threshold", 0.05};
         Gaudi::Property<float> m_BField   {this, "BField", -3};
         Gaudi::Property<float> m_eps     { this, "eps"   , 1e-6  };//very small value, it is returned dedx for unsimulated step (may needed for SimTrackerHit)
+        Gaudi::Property<float> m_gaspressure { this, "gaspressure"   , 760.  };// default gas pressure, 760 Torr. 1 ATM
         // Output collections
         DataHandle<edm4hep::SimPrimaryIonizationClusterCollection>    m_SimPrimaryIonizationColWriter{"SimPrimaryIonizationClusterCollection", Gaudi::DataHandle::Writer, this};
         edm4hep::SimPrimaryIonizationClusterCollection* m_SimPrimaryIonizationCol;