To evaluate the status of each BEMC tower, its ADC spectrum is tested for various features.  If a test fails, then a bit (or multiple bits) is flipped to indicate the nature of the problem with the tower.  It is possible for a tower to fail multiple tests and therefore have a status code which indicates multiple problems.  In this blog I show examples of towers which fail each of the basic tests and are therefore assigned specific status codes.  

The status codes are defined as follows:

000 == channel does not exist or is masked in L2ped
001 == channel is good
002 == channel is either hot or cold (see bit 16)
004 == channel has a weird pedestal (see bit 32)
008 == channel has a stuck bit (see bits 64 and 128)
016 == if off, hot (10x as many hits); if on, cold tower (10x fewer hits)
032 == if off, pedestal mean is out of bounds; if on, pedestal width is too large/small
064 == bit stuck on
128 == bit stuck off
254 == identical channel

These codes can be seen by going to the EMC Status webpage (http://online.star.bnl.gov/emcStatus/ or for any given year http://online.star.bnl.gov/emcStatus2012/) and clicking on any of the Details pages. 

I show examples from a heavy ion (U+U) run where the numbers of counts in the histograms are higher than in p+p, for clarity.  All these plots come from http://online.star.bnl.gov/emcStatus2012/UU193/pdf/bemcStatus_F16832_R13127041_R13127054.pdf

status = 1 (normal ADC spectrum)

status = 0  (channel is masked out)
Note: MOST of the channels marked with a zero status are (or were) hot channels that were caught and masked out. 

status = 2 (hot channel)
Hot channels look like the above plot, and most of them are caught in realtime and masked out, and thus assigned a status of zero.  It is unusual to actually catch a really hot channel after the fact. 

status = 18 = 2+16 (cold channel)

status = 4 or 36 (bad pedestal)
This status catches a range of problems, from weird-looking spectra (like shown here), to wide pedestals, etc.

status = 72 = 8+64 (stuck bit - on)

status = 136 = 8+128 (stuck bit - off)

status = 254 (identical channels)