diff --git a/source/geometries/Next100.cc b/source/geometries/Next100.cc
index 908c6c1410..5088089902 100644
--- a/source/geometries/Next100.cc
+++ b/source/geometries/Next100.cc
@@ -239,6 +239,7 @@ namespace nexus {
     else if ((region == "CENTER") ||
              (region == "ACTIVE") ||
              (region == "CATHODE_RING") ||
+             (region == "CATHODE_SURF") ||
              (region == "BUFFER") ||
              (region == "XENON") ||
              (region == "LIGHT_TUBE") ||
diff --git a/source/geometries/Next100FieldCage.cc b/source/geometries/Next100FieldCage.cc
index 8a9bca8d9f..b33b74b3c6 100644
--- a/source/geometries/Next100FieldCage.cc
+++ b/source/geometries/Next100FieldCage.cc
@@ -480,6 +480,14 @@ void Next100FieldCage::BuildCathode()
                                            GetCoordOrigin().y(),
                                            cathode_zpos_));
 
+  // Generate in a small 1 micron thick disk in front of cathode
+  cathode_surf_gen_ =
+    new CylinderPointSampler(0.0, cathode_int_diam_/2.,
+                             0.5*micrometer,0., twopi, nullptr,
+                             G4ThreeVector(GetCoordOrigin().x(),
+                                           GetCoordOrigin().y(),
+                                           cathode_grid_zpos - grid_thickn_ - 0.5*micrometer));
+
 
   /// Visibilities
   G4VisAttributes cathode_col = nexus::DarkGrey();
@@ -1079,6 +1087,7 @@ Next100FieldCage::~Next100FieldCage()
   delete hdpe_gen_;
   delete ring_gen_;
   delete cathode_gen_;
+  delete cathode_surf_gen_;
   delete gate_gen_;
   delete anode_gen_;
   delete holder_gen_;
@@ -1109,6 +1118,10 @@ G4ThreeVector Next100FieldCage::GenerateVertex(const G4String& region) const
     vertex = cathode_gen_->GenerateVertex(VOLUME);
   }
 
+  else if (region == "CATHODE_SURF"){
+    vertex = cathode_surf_gen_->GenerateVertex(VOLUME);
+  }
+
   else if (region == "BUFFER") {
     G4VPhysicalVolume *VertexVolume;
     do {
diff --git a/source/geometries/Next100FieldCage.h b/source/geometries/Next100FieldCage.h
index f78f13801d..095d26fd29 100644
--- a/source/geometries/Next100FieldCage.h
+++ b/source/geometries/Next100FieldCage.h
@@ -112,6 +112,7 @@ namespace nexus {
     CylinderPointSampler* hdpe_gen_;
     CylinderPointSampler* ring_gen_;
     CylinderPointSampler* cathode_gen_;
+    CylinderPointSampler* cathode_surf_gen_;
     CylinderPointSampler* gate_gen_;
     CylinderPointSampler* anode_gen_;
     CylinderPointSampler* holder_gen_;
diff --git a/source/geometries/Next100InnerElements.cc b/source/geometries/Next100InnerElements.cc
index 78d510c1f7..0ca2e9f315 100644
--- a/source/geometries/Next100InnerElements.cc
+++ b/source/geometries/Next100InnerElements.cc
@@ -103,6 +103,7 @@ namespace nexus {
     if ((region == "CENTER") ||
         (region == "ACTIVE") ||
         (region == "CATHODE_RING") ||
+        (region == "CATHODE_SURF") ||
         (region == "BUFFER") ||
         (region == "XENON")  ||
         (region == "S2_PMT_LT") ||