For the previous installment of this study (prior to the pre-post fix), go here: drupal.star.bnl.gov/STAR/blog/lisa/further-study-bbc-epd-correlations-pre-2018-run-cosmics


Thanks to Rosi's detective work, we are now in the correct prepost, and the spatial correlations between EPD and BBC are much more reasonable.

However, there are still issues.  Please download this pdf, and flip through it.

While the correlation looks good, there are still problems with one of the boards.  It turns out that Steve had swapped this board after a pedestal run had been taken (see this mail).  Rosi looked at files after another pedestal run had been taken, and this should have fixed the problem (see this mail).  The resulting analysis can be found at the bottom of this page, but since everything is now fixed, that means we bid the following image adieu...

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Update 8 March 2018 - Rosi got the code running (always an important step that others can use code) on the post-new-pedestal data, and indeed the problem is fixed.  (Though..... I do not understand why a "wrong" pedestal makes a "fat" pedestal...)  Download the pdf file here


Further update 8 March 2018 -

Usually the BBC multiplicity is unity, but sometimes it is higher.  If we look only at events where one BBC PMT fires, then the correlation is significantly stronger.  (Still low statistics.)  Please download the pdf here.

We want to look at TAC-TAC correlations between BBC phototubes and EPD tiles.  (This is a geometric pain in the neck, can I just say?  But I have written the utilities to handle this into the StEpdUtil/ package.  You are welcome.)  Anyway, we only want to look at tiles which have spatial overlap.  Here is the relevant geometry.  (Note that tile numbers of the BBC are listed.  The mapping to phototubes is less trivial.)

An EPD tile has overlap with between 0 and three BBC tiles
A BBC tile has overlap with either 8 or 10 EPD tiles.  (In many cases, the overlap is very small.)