[Hps-analysis] [EXTERNAL] Understanding 2021 discrepancies

[Nelson, Timothy Knight]

Hello Norman,

We’ve been discussing the differences in these two plots which should in principle be similar.  Some things I notice here:

1) For tracks on the electron side (phi0 < ~0.045), they appear very similar.
2) For tracks on the positron side, you have a “bifurcation”.  However, the momentum width of each peak is unphysically narrow: better than the ideal resolution of the tracker.
3 The two “peaks” on the positron side appear to lie on the same p vs. phi0 trend line (these are correlated by construction).

Together, (2) and (3) suggest that these are not actually two peaks, but rather that - for some reason - you are not reconstructing many of the tracks on the positron side, and that is actually shaping the distributions there.  This is further supported by the appearance of a hard cutoff in statistics on the line at ~0.045 which does not appear in Cameron’s plot.

So, I wonder if there could be some cut (chisq?) that is causing you not to plot a large number of the slot side tracks.  Things to try:

- Make this plot for the same run that Cam is using (to be sure not something real in the detector)
- Compare N(phi0 < 0.045)/N(phi0 > 0.045) with Cameron to see if it does seem like you are reconstructing fewer tracks on that side.

Best,
Tim



[cid:EDB7ED43-2DFA-43AF-B0AF-08DC4A395534]
[cid:C13B4310-2E3A-4D2C-A702-1B7A9CF1F35B]

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