University of Liverpool

NN PID (so far)

David Payne      

I've put together this short page of conclusions to my NN PID work so far.
Earlier presentations can be seen here. There were a couple of open item from last time - adding number of hits to improve discrimination at low energy (which worked pretty well, used in the results shown here, cheers ian), and using Yoshi's stipped files (here) for a simpler demonstration of performance. I'm using the 30 degree files (pion-, electron, mu-) and only working with the DS ecal. In all cases the neural net is trained on events with a flat energy distribution (to avoid any bias) but the performance plots shown here use events generated with yoshi's macros. In the plots below I'm assuming equal initial numbers of mu-/e-/pi-.

Pion Electron Seperation

In the plots below the X axis represents the neural net output. The blue curve (Y axis, left) shows  the electron efficiency for a cut on nn output of that value, and the red curve (Y axis, right) shows the the fraction of pions in the selected sample for that cut.

First, without any track info:
e- pi-, no track
Second, with perfect track info:
e- pi-, perfect track

Muon Electron PID

As a test, I did exactly the same thing with mu-/e- seperation. Seems to work pretty well. In the plots below the X axis represents the neural net output. The blue curve (Y axis, left) shows  the electron efficiency for a cut on nn output of that value, and the red curve (Y axis, right) shows the the fraction of muons in the selected sample for that cut. I didn't use any track info (takes all the fun out of it).
Muon Electron PID (no track)