Conclusions and Questions: 

Did we really load new ALCT firmware? No difference in results for the
0 degree angle of incidence. 

When nph_pattern was changed only for ME2/2 and ME3/2, why did the
ghost rate drop >10X for ME1/2 and ME1/1?????   Meanwhile, chambers
ME2/2 and ME3/2 stayed the same. Constants loaded for all chambers?
The efficiency did drop for ME2/2 and ME3/2 (96% -> 86%) indicating
that more layers were required in coincidence.

For the 28 degree angle of incidence, the ghost probability is high
for trig_modes = 0, 3 (collision and accelerator patterns on)
This confirms earlier study done during 9/03 beam test, where 40-45%
probability was found for trig_mode=3. We see the same this year, but
not in ME1/2 or ME1/1 (Smaller wire group spacing?).

Collision patterns fire efficiently even for 0 degree incidence, even
for 6/6 pattern (85%).

Accelerator patterns fire efficiently even for 28 degree incidence,
even for 6/6 patterns (87%).

Thus, we don't have much discrimination between the two types of muon
trajectories, which limits how useful the accelerator muon patterns
are. 

For 28 degree incidence, the ghost rate is lower (20-30%) 
for trig_mode = 0 (accelerator or collision patterns allowed), 
than  for trig_mode = 3 (accelerator kills collision pattern)
where it is 40-50%, for chambers ME2/2 and ME3/2.  
However, the situation is opposite for ME1/2 and ME1/1, where the
ghost rate is 60-75% for trig_mode=0 and 5-7% for trig_mode = 3.  
Why?

Why is the efficiency lower for trig_mode=0 (collision or accelerator
patterns) than for trig_mode = 2 (collision only)?

The lowest ghost rate configuration seems to be for trig_mode=2
(collision patterns only). For 28 degree incidence, it is 5% for 4
layer coincidence and  3% for 5 layers. Corresponding efficiency is
99.2% and 97% respectively, for ME2/2.  

I would recommend staying with our defaults:

trig_mode = 2   (collision patterns only)
nph_pattern = 4 (4 layer coincidence)

To get the best efficiency and lowest ghost rate.  


Regards,
          Darin