diff --git a/cli/simulate_pixels.py b/cli/simulate_pixels.py
index da9efa2b..a4b35cfe 100755
--- a/cli/simulate_pixels.py
+++ b/cli/simulate_pixels.py
@@ -722,6 +722,7 @@ def save_results(event_times, is_first_batch, results, i_mod=-1, light_only=Fals
                 n_light_ticks = int((light.LIGHT_WINDOW[1] + light.LIGHT_WINDOW[0])/light.LIGHT_TICK_SIZE)
 
                 light_response = cp.zeros((n_light_det,n_light_ticks), dtype='f4')
+                #light_response += cp.array(light_sim.gen_light_detector_noise(light_response.shape, light_noise[op_channel.get()]))
                 light_response_true_track_id = cp.full((n_light_det, n_light_ticks, light.MAX_MC_TRUTH_IDS), -1, dtype='i8')
                 light_response_true_photons = cp.zeros((n_light_det, n_light_ticks, light.MAX_MC_TRUTH_IDS), dtype='f8')
 
@@ -795,8 +796,6 @@ def save_results(event_times, is_first_batch, results, i_mod=-1, light_only=Fals
                 # Nothing to simulate for charge readout?
                 continue
 
-                
-
             for itrk in tqdm(range(0, evt_tracks.shape[0], sim.BATCH_SIZE),
                              delay=1, desc='  Simulating event %i batches...' % ievd, leave=False, ncols=80):
                 if itrk > 0:
@@ -1019,7 +1018,7 @@ def save_results(event_times, is_first_batch, results, i_mod=-1, light_only=Fals
                     light_sim.calc_light_detector_response[BPG, TPB](
                         light_sample_inc_disc, light_sample_inc_scint_true_track_id, light_sample_inc_scint_true_photons,
                         light_response, light_response_true_track_id, light_response_true_photons)
-                    light_response += cp.array(light_sim.gen_light_detector_noise(light_response.shape, light_noise[op_channel.get()]))
+                    #light_response += cp.array(light_sim.gen_light_detector_noise(light_response.shape, light_noise[op_channel.get()]))
                     RangePop()
 
                     RangePush("sim_light_triggers")
diff --git a/larndsim/light_sim.py b/larndsim/light_sim.py
index 1460eb0c..aa34d11d 100644
--- a/larndsim/light_sim.py
+++ b/larndsim/light_sim.py
@@ -505,7 +505,8 @@ def digitize_signal(signal, signal_op_channel_idx, trigger_idx, trigger_op_chann
     if itrig < digit_signal.shape[0]:
         if idet_module < digit_signal.shape[1]:
             if isample < digit_signal.shape[2]:
-                sample_tick = isample * light.LIGHT_DIGIT_SAMPLE_SPACING / light.LIGHT_TICK_SIZE - light.LIGHT_TRIG_WINDOW[0] / light.LIGHT_TICK_SIZE + trigger_idx[itrig]
+                #sample_tick = isample * light.LIGHT_DIGIT_SAMPLE_SPACING / light.LIGHT_TICK_SIZE - light.LIGHT_TRIG_WINDOW[0] / light.LIGHT_TICK_SIZE + trigger_idx[itrig]
+                sample_tick = isample * light.LIGHT_DIGIT_SAMPLE_SPACING / light.LIGHT_TICK_SIZE
                 idet = trigger_op_channel_idx[itrig, idet_module]
                 idet_signal = 0
                 for idet_signal in range(signal.shape[0]):
@@ -584,7 +585,9 @@ def sim_triggers(bpg, tpb, signal, signal_op_channel_idx, signal_true_track_id,
     pre_digit_ticks = int(ceil(light.LIGHT_TRIG_WINDOW[0]/light.LIGHT_TICK_SIZE))
     if trigger_idx.min() - pre_digit_ticks < 0:
         pad_shape = (signal.shape[0], int(pre_digit_ticks - trigger_idx.min()))
-        signal = cp.concatenate([gen_light_detector_noise(pad_shape, light_det_noise[signal_op_channel_idx]), signal], axis=-1)
+        pre_trig_readout = cp.zeros(pad_shape)
+        signal = cp.concatenate([pre_trig_readout, signal], axis=-1)
+        #signal = cp.concatenate([gen_light_detector_noise(pad_shape, light_det_noise[signal_op_channel_idx]), signal], axis=-1)
         signal_true_track_id = cp.concatenate([cp.full(pad_shape + signal_true_track_id.shape[-1:], -1, dtype=signal_true_track_id.dtype), signal_true_track_id], axis=-2)
         signal_true_photons = cp.concatenate([cp.zeros(pad_shape + signal_true_photons.shape[-1:], signal_true_photons.dtype), signal_true_photons], axis=-2)
         padded_trigger_idx += pad_shape[1]
@@ -593,11 +596,15 @@ def sim_triggers(bpg, tpb, signal, signal_op_channel_idx, signal_true_track_id,
     post_digit_ticks = int(ceil(light.LIGHT_TRIG_WINDOW[1]/light.LIGHT_TICK_SIZE))
     if post_digit_ticks + padded_trigger_idx.max() > signal.shape[1]:
         pad_shape = (signal.shape[0], int(post_digit_ticks + padded_trigger_idx.max() - signal.shape[1]))
-
-        signal = cp.concatenate([signal, gen_light_detector_noise(pad_shape, light_det_noise[signal_op_channel_idx])], axis=-1)
+        post_trig_readout = cp.zeros(pad_shape)
+        signal = cp.concatenate([signal, post_trig_readout], axis=-1)
+        #signal = cp.concatenate([signal, gen_light_detector_noise(pad_shape, light_det_noise[signal_op_channel_idx])], axis=-1)
         signal_true_track_id = cp.concatenate([signal_true_track_id, cp.full(pad_shape + signal_true_track_id.shape[-1:], -1, dtype=signal_true_track_id.dtype)], axis=-2)
         signal_true_photons = cp.concatenate([signal_true_photons, cp.zeros(pad_shape + signal_true_photons.shape[-1:], dtype=signal_true_photons.dtype)], axis=-2)
 
+    # add noise to padded (in readout time) signal
+    signal += cp.array(gen_light_detector_noise(signal.shape, light_det_noise[signal_op_channel_idx]))
+
     # add noise for any channels that had no signal
     if cp.any(~cp.isin(op_channel_idx, signal_op_channel_idx)):
         missing = cp.unique(op_channel_idx[~cp.isin(op_channel_idx, signal_op_channel_idx)])