ESMD (MAPMT FEE) Timing for Run 9


The timing scans for ESMD/MAPMT FEE for Run 9 were taken by
raising the box delay settings as far as feasible, staying
within the present RHIC tic "c" delay setting and then varying
the TCD phase delay in order to see as much as possible of the
right-hand-side timing cutoff in the scans (Note: due to present
nature of the various delays there is a timing "hole" which
cannot be accessed ... we will try to fix in future years e.g.,
by extending the delay range of the new TCD).

The new MAPMT configuration files for the scans were put on the
EEMC slow controls machine (eemc-sc) in directory:
/home/online/mapmtConfig/03-01-09_scan. The initial conditions
are outlined in cols 1-7 of the spreadsheet "MAPMT_DELAYS_v7"
(among the last attachments below). The nominal TDC phase setting
from previous years is = 65. Within allowable additions to
the box delay, we chose to divide things into 4 classes:

a) add 22 ns box delay as per cols 8-12 of spreadsheet:
(should clearly see edge as in previous years):
12S1-12P1, 2S3, 4S1-4S3, 7S1-7P1, 8S2-10P1

b) add 17 ns box delay as per cols 15-19 of spreadsheet:
(will see less but better than previous):
1S1, 1S3, 2S1, 4P1, 8S1, 11S1, 11S3

c) add 7 ns box delay as per cols 22-26 of spreadsheet:
(will see even less, etc.):
1P1, 2S2, 2P1-3S3, 5S1, 5S3, 6S1, 8S2, 6P1, 11S2, 11P1

d) delay w/ truncation @ 400 HEX as per cols 22-26 of
(mistake: see notes below ... max is really 3FF)
1S2 (439), 3P1 (44E), 5P1 (40C), 6s3 (423)

Data for the scans was taken on Friday 6 March 2009:

Phase Phase
10065031 80 80
10065032 10 10
10065033 20 20
10065034 30 30
10065035 40 40
10065036 50 50
10065037 60 60
10065038 70 70
10065039 75 75
10065040 65 65
10065041 55 55
10065042 45 45
10065043 35 35
10065044 25 25
10065045 15 15
10065046 5 5
10065047 0 0
(in last entry at "0" peds seem to indicate this didn't work
for ETOW ... too many counts in spectra)

These data were analyzed by Alice Bridgeman at link:

Attached below are the same plots from her analysis, but
annotated to show the run 8 effective timing setting (long
vertical line at 43, 48, 58 depending on box ("crate"), for
added delays of 22, 17 and 7, respectively) as well as
indication of the location of the "right edge" of the timing
scan and length of flat top region. (The files for the good
timing scans are appended first and in order below for crates
64 [e.g., mapmt-crate-64_set.pdf], 66-68, 70-78, 80-84, 86,
88-89, 91-94, and 96-111.) The associated values from this
somewhat subjective procedure (regions selected by eye and
computer drawing "straight edge"), are given in cols 29-33
(again on spreadsheet "MAPMT_DELAYS_v7) for the distance to the
edge, range of distances, flattop range and time difference to
near edge, respectively.

In the past we have tried to set the delays so that that we
sit (operating point) about 12 ns into the plateau region from
the right side timing edge ... this allows for several ns of
"time jitter" as well as possible error in determining the edge
while still maintaining a safe (estimate > 5 ns) distance of
the effective operation point from the fall off edge. The
projected adjustments are given in col 36 of "MAPMT_DELAYS_v7"
and converted to final box delay in HEX in col 39.

These scans are more definitive that those of previous years
(due to mixture of issues) and hence the new values bounce
around a bit, but in general the shifts are only ~ few ns with
a few outliers.

There are several special cases!

For boxes 65 (12S2), 69 (1S2), 79 (3P1), 85 (5S2), 87 (5P1),
90 (6S3), the box delay was set to "400" instead of the max
allowed of "3FF" (a mistake as noted above) which effectively
zeroed out the box delay causing just the left hand timing edge
to be visible in the scans (for box 95 7P1 plots there is something
else is wrong and very little is plotted).

For these special cases one can estimate the timing by looking at the
LHS edge and applying the 50-55ns flat top to guess where the leading
edge is (e.g., see the plots). But in general for these case the timing
was set by looking at neighboring boxes in the clock chain and deducing
a value to use (see spread sheet).

The final Hex delay values are indicated in one of the last columns of
the spreadsheet (MAPMT_DELAYS_v7)