fixed obs level

Documentation/Examples/em_shower.cc

@@ -151,8 +151,8 @@ int main(int argc, char** argv) {
   process::longitudinal_profile::LongitudinalProfile longprof{showerAxis};
 
   Plane const obsPlane(showerCore, Vector<dimensionless_d>(rootCS, {0., 0., 1.}));
-  process::observation_plane::ObservationPlane observationLevel(obsPlane,
-                                                                "particles.dat");
+  process::observation_plane::ObservationPlane observationLevel(
+								obsPlane, Vector<dimensionless_d>(rootCS, {1., 0., 0.}), "particles.dat");
 
   auto sequence = process::sequence(proposalCounted, em_continuous, longprof, cut,
                                     observationLevel, trackWriter);