fix

Author: jokasimr

src/ess/reduce/time_of_flight/lut.py

@@ -420,7 +420,7 @@ def simulate_chopper_cascade_using_tof(
             else tof.Clockwise,
             open=ch.slit_begin,
             close=ch.slit_end,
-            phase=abs(ch.phase),
+            phase=ch.phase if ch.frequency.value > 0.0 else -ch.phase,
             distance=sc.norm(
                 ch.axle_position - source_position.to(unit=ch.axle_position.unit)
             ),