Run 8 (9GeV AuAu)
The calibration production pass used the entire low energy AuAu dataset with the chain: "VtxSeedCalG,B2008,ITTF,VFMinuit,Corr4". Only 2 fills were found - apparently the collider folks did not update their fill numbers because judging from the BBC coincidence rate vs. time (shown here as seconds since Nov. 25, 2007 00:00:00) there were at least 14 fills during which we took runs (shown in red):
Despite having a cut at r^2 < 15 cm^2 for the vertices used, the beampipe is still clearly seen in low multiplicity collisions:
Here is log10(r^2) vs. log10(mult):
I proceeded with a cut at r^2 < 1.6 cm^2 and began to calibrate these 14 fills when I noticed that run 9071070 has a clearly different y distribution than run 9071067, despite the two appearing to me to be in the same fill from their BBC coincidence rate:
Here is a blowup of that fill's BBC rate where the following runs (last 2 digits of the run number only) are shown: 67 (red), 68 (green), 70 (blue), 72 (magenta):
The Electronic Shift Log includes a note for run 70: "Beam cogged at STAR." I decided to treat run 70 as it's own fill and got the following distribution for the beamline constraints of the 14 fills (14 original, plus the run 70 one, minus one which simply had far too few statistics):
Based upon the variations and time gaps seen in the above plot, I decided to group these into 4 "super-fills" as runs:
9071036-9071053
9071055-9071067
9071070-9071077
9071079-9071097
The result is shown here:
I have additionally tried to separate the calibration by trigger ID:
In the lowEnergy2008 setup, 1 = bbc-ctb, and 2 = bbc.
In the bbcvpd setup, 1 = bbc, and 2 = vpd.
In all cases, there were too few with id = 2 to make a solid calibration, but the distributions from both id values were consistent enough to say that no evidence of biases from the triggers can be identified.
Lastly, after subtracting off the z dependence, and weighting each vertex by the sqrt of the multiplicity, I find distributions which are well-described by Gaussians all giving sigmas of about 1.5mm in x and y. Shown are these distributions for the 4 fills in chronological order from top to bottom, x on the left, y on the right:
