I have placed a cut to require a single hit in TOF1 and a coincidence between TOF12. I have then plotted the number of spacepoints that are not used to make a track (see unused_spacepoints.pdf). This plot shows:

1. 0 missing, correctly found tracks with no-noise (or entirely missed the detector)
2. 1,2 missing, probably noise hits.
3. spike at 5 missing!! this means something which most likely hit every plane, but was not transformed into a track. This happens:
7% of hits in the upstream
15% of hits in the downstream.

I remember when we looked at the tracker paper there was a dropoff in efficiency at low Pt and Pz. The plot in the tracker paper does not go below 140MeV/c because we did not expect to be running there.

In a perfect (MC) world, we did the efficiency studies for the tracker paper. I dug up(and annotated) an old plot (see attached).

As you can see we are starting to run in the Pz efficiency drop off region. From the plot I'd expect something like a 95% efficiency, so:
1. The upstream is close to being explained,
2. Downstream requires further investigation.

I looked at a 240MeV run to see if things improved. The answer is they did:

Downstream efficiency is still low (96%) and the upstream efficiency is 98%. The problem is dominated by some feature the low momentum introduces.

The next step is to run a MC simulation of the BL at 140MeV, with fields like those in the channel.

Plots for MC and Data run 8681.

Data cards to fire a pencil beam through the downstream tracker.

Download the tarball. Then do

source /path/to/maus/env.sh
tar -xzf tracker-beam-generation.tar.gz
bash do_geometry.bash # download the geometry for 8681
python $MAUS_ROOT_DIR/bin/simulate_mice.py --configuration_file config.py

• MAUS does support python code in the datacards, so you can e.g. wrap the "definitions" list using a function or something if you want to loop over several events. Just watch that the number of events per spill doesnt get too big (more than 1k or so).
• You can switch off scattering using the physics_processes data card if you like.