diff --git a/docs/changes/1940.maintenance.md b/docs/changes/1940.maintenance.md
new file mode 100644
index 0000000000..4d01b23dd1
--- /dev/null
+++ b/docs/changes/1940.maintenance.md
@@ -0,0 +1 @@
+Add search patterns in integration tests and fix bug when using an isotropic angular distribution in the illuminator simulations.
diff --git a/src/simtools/simtel/simulator_light_emission.py b/src/simtools/simtel/simulator_light_emission.py
index 81c934e524..0cd5981827 100644
--- a/src/simtools/simtel/simulator_light_emission.py
+++ b/src/simtools/simtel/simulator_light_emission.py
@@ -546,6 +546,9 @@ def _get_angular_distribution_string_for_sim_telarray(self):
                 )
                 return option_string
 
+        if option_string == "isotropic":
+            return option_string
+
         width = self.calibration_model.get_parameter_value_with_unit(
             "flasher_angular_distribution_width"
         )
diff --git a/tests/integration_tests/config/simulate_illuminator_configurable_position.yml b/tests/integration_tests/config/simulate_illuminator_configurable_position.yml
index e7cdc48ca8..da12cd182d 100644
--- a/tests/integration_tests/config/simulate_illuminator_configurable_position.yml
+++ b/tests/integration_tests/config/simulate_illuminator_configurable_position.yml
@@ -18,8 +18,23 @@ applications:
     test: true
     log_level: DEBUG
   integration_tests:
-  - output_file: logfile.log
-  - output_file: xyzls.simtel.zst
+  - test_output_files:
+    - file: logfile.log
+      path_descriptor: output_path
+    - file: xyzls.simtel.zst
+      path_descriptor: output_path
+    - expected_log_output:
+      pattern:
+      - "Initialize for run"
+      - "Total number of photons produced in this run"
+      - "Sim_telarray finished at"
+      - "CORSIKA IACT finished at"
+      - "Tel. triggered:"
+      - "Finished."
+      forbidden_pattern:
+      - "Error"
+      file: logfile.log
+      path_descriptor: output_path
   model_version_use_current: true
   test_name: run-configurable-position
 schema_name: application_workflow.metaschema
diff --git a/tests/integration_tests/config/simulate_illuminator_layout.yml b/tests/integration_tests/config/simulate_illuminator_layout.yml
index dc0483231f..05f84a359a 100644
--- a/tests/integration_tests/config/simulate_illuminator_layout.yml
+++ b/tests/integration_tests/config/simulate_illuminator_layout.yml
@@ -10,8 +10,23 @@ applications:
     test: true
     log_level: DEBUG
   integration_tests:
-  - output_file: logfile.log
-  - output_file: xyzls.simtel.zst
+  - test_output_files:
+    - file: logfile.log
+      path_descriptor: output_path
+    - file: xyzls.simtel.zst
+      path_descriptor: output_path
+    - expected_log_output:
+      pattern:
+      - "Initialize for run"
+      - "Total number of photons produced in this run"
+      - "Sim_telarray finished at"
+      - "CORSIKA IACT finished at"
+      - "Tel. triggered:"
+      - "Finished."
+      forbidden_pattern:
+      - "Error"
+      file: logfile.log
+      path_descriptor: output_path
   model_version_use_current: true
   test_name: run-layout
 schema_name: application_workflow.metaschema
diff --git a/tests/unit_tests/simtel/test_simulator_light_emission.py b/tests/unit_tests/simtel/test_simulator_light_emission.py
index 3a7a9fd289..935d9a371e 100644
--- a/tests/unit_tests/simtel/test_simulator_light_emission.py
+++ b/tests/unit_tests/simtel/test_simulator_light_emission.py
@@ -1610,3 +1610,20 @@ def test__calibration_pointing_direction_with_custom_params(simulator_instance):
     simulator_instance.telescope_model.get_parameter_value_with_unit.assert_called_with(
         "array_element_position_ground"
     )
+
+
+def test__get_angular_distribution_string_for_sim_telarray_isotropic(simulator_instance):
+    """Test isotropic distribution returns just the token."""
+    simulator_instance.calibration_model.get_parameter_value.return_value = "Isotropic"
+
+    # Even if width is available (though it shouldn't be for isotropic), it should be ignored
+    mock_width = Mock()
+    mock_width.to.return_value.value = 10.0
+    simulator_instance.calibration_model.get_parameter_value_with_unit.return_value = mock_width
+
+    result = simulator_instance._get_angular_distribution_string_for_sim_telarray()
+    assert result == "isotropic"
+
+    # Verify width was NOT requested: the implementation returns early for isotropic distributions
+    # before attempting to fetch the width via get_parameter_value_with_unit.
+    simulator_instance.calibration_model.get_parameter_value_with_unit.assert_not_called()