Pedestal Correction in action (but still during shutdown)
Philippe Laurens Michigan State University 16-Oct-2007
Slide 2
Active Control of Trigger Tower Zero Energy Response L1Cal TCC
can now automatically track and correct the Zero Energy Response
for the Transverse Energy of each Trigger Tower, at the output from
the ADF cards, i.e. the input to the TAB Cards, to remain at the
design value of 8 counts = 0 GeV. For each Trigger Tower, the Zero
Energy Response Drift is measured from the average of 1000 samples
of Live Crossing Energy. If the measured drift is below a
programmed threshold (0.5 counts) TCC immediately applies 50% of
the correction needed to correct the measured drift. If the
measured drift is above the threshold, TCC does not make any
correction and waits until the next sample to decide if this is a
spike or a step change. At the next snapshot, and if this was a
spike, do nothing and return to the 50% correction mode for future
correction cycles. If this is a step, do the full correction
instantly and return to the 50% method for future corrections.
These decisions are taken on a tower by tower basis.
Slide 3
Comparison of pedestal stability with/without active correction
Examine a few of the quiet, and some of the noisiest Trigger Towers
and compare: Store 5435 (17&18-May-2007) No beam period 5438 to
5443 (19-May-2007) Active correction during shutdown 09-Oct-2007
Active correction during shutdown 10-Oct-2007
Slide 4
Averages of all Trigger Towers Physics Running Between Stores
(Old) (Current) StdDev of Averages of all TTs is ~0 (with spikes)
and Average of Abs(Drift) is ~0 Physics Running Between Stores
Slide 5
Individual Towers: EM_TT(- 2, 5) (Current) Physics Store
Between Stores (Old) (Current)
Slide 6
EM_TT(- 2, 5) Corresponding Control Values
Slide 7
EM_TT(+ 8,26)
Slide 8
Slide 9
HD_TT(- 2, 5)
Slide 10
Slide 11
HD_TT(- 6,26)
Slide 12
Slide 13
HD_TT(- 8, 9)
Slide 14
Slide 15
Looking back at oversampled data 2006 studies for HD_TT(- 8, 9)
ADF captures 4 sampling points per tick 1:159 Each point in the
graph is the average (or StdDev) of 1000 samples
