diff --git a/compact/erich.xml b/compact/erich.xml
index 8d1719a85e88f654fda505608a207c31367d87c2..bc10dab47095515c52391cdd29bf3ab70f542ea8 100644
--- a/compact/erich.xml
+++ b/compact/erich.xml
@@ -158,9 +158,9 @@
 <services>
   <comment> SJJ: random standin for readout + electronics + cooling @FIXME </comment>
   <component name="aluminum" thickness="5*mm" vis="RICHServiceVis" material="Aluminum"/>
-  <component name="air" thickness="30*mm" material="Aluminum"/>
+  <component name="air" thickness="20*mm" material="Air"/>
   <component name="aluminum" thickness="5*mm" vis="RICHServiceVis" material="Aluminum"/>
-  <component name="air" thickness="30*mm" material="Aluminum"/>
+  <component name="air" thickness="20*mm" material="Air"/>
   <component name="aluminum" thickness="5*mm" vis="RICHServiceVis" material="Aluminum"/>
 </services>
 
diff --git a/src/ERich_geo.cpp b/src/ERich_geo.cpp
index 19bf3f4653b1fca8c5bde61756480522d6500559..76ef437a1c8562de30c806cde34cf42fde5657c3 100644
--- a/src/ERich_geo.cpp
+++ b/src/ERich_geo.cpp
@@ -283,7 +283,7 @@ static Ref_t createDetector(Detector& desc, xml::Handle_t handle, SensitiveDetec
     for (xml_coll_t ci(x_service, _Unicode(component)); ci; ++ci, ncomponents++) {
       xml_comp_t x_comp    = ci;
       double     thickness = x_comp.thickness();
-      Tube       c_tube{sensorPlaneRmin, sensorPlaneRmax, thickness};
+      Tube       c_tube{sensorPlaneRmin, sensorPlaneRmax, thickness/2};
       Volume     c_vol{_toString(ncomponents, "component%d"), c_tube, desc.material(x_comp.materialStr())};
       c_vol.setVisAttributes(desc, x_comp.visStr());
       service_vol.placeVolume(c_vol, Position(0, 0, thickness_sum + thickness / 2.0));