Feature #1897

Suspect poor tracker efficiency

Added by Rogers, Chris over 7 years ago. Updated over 7 years ago.

Start date:
24 November 2016
Due date:
% Done:


Estimated time:


Digging into tracker efficiency for e.g. run 8593...


unused_spacepoints.pdf (13.7 KB) unused_spacepoints.pdf spacepoints not used in tracks. Overton, Edward, 02 December 2016 14:25
hunt_us_track_efficiency.pdf (33.3 KB) hunt_us_track_efficiency.pdf Overton, Edward, 02 December 2016 14:48
unused_spacepoints_240.pdf (13.6 KB) unused_spacepoints_240.pdf Overton, Edward, 02 December 2016 15:44
8681.tar.gz (3.36 MB) 8681.tar.gz Rogers, Chris, 07 December 2016 12:38
tracker-beam-generation.tar.gz (63 KB) tracker-beam-generation.tar.gz Rogers, Chris, 07 December 2016 16:29

Updated by Rogers, Chris over 7 years ago

See, for example, slide 11 of VC talk 1st December

The scripts used to produce those plots was this one:

For the track extrapolation you need to install this MAUS version:


Updated by Overton, Edward over 7 years ago

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.


Updated by Overton, Edward over 7 years ago

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.


Updated by Overton, Edward over 7 years ago

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.


Updated by Rogers, Chris over 7 years ago

Plots for MC and Data run 8681.


Updated by Rogers, Chris over 7 years ago

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

Download the tarball. Then do

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

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