diff --git a/js/spin/model/SpinModel.ts b/js/spin/model/SpinModel.ts
index 9aeb441..3dcd167 100644
--- a/js/spin/model/SpinModel.ts
+++ b/js/spin/model/SpinModel.ts
@@ -414,6 +414,15 @@ export default class SpinModel implements TModel {
             particle.reset();
           }
         }
+
+        const secondDetectorPosition = this.sternGerlachs[ 1 ].positionProperty.value.plus( BLOCKER_OFFSET ).x;
+        if ( particle.positionProperty.value.x >= secondDetectorPosition ) {
+          if ( !particle.wasCounted[ 2 ] ) {
+            // Regardless which SG is active, we count the particles in the SG1
+            this.sternGerlachs[ 1 ].count( particle.isSpinUp[ 2 ] );
+            particle.wasCounted[ 2 ] = true;
+          }
+        }
       } );
     }
   }