CHANTI Update and High rate effects
Fabio Ambrosino,
Tiziana Capussela,
Michele Corvino (B.Sc.),
Domenico Di Filippo,
Paolo Massarotti,
Marco Mirra,
Marco Napolitano,
Giulio Saracino
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Domenico Di Filippo
CHANTI Status
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100% of bars to produce 6 additional stations
completed
We need ~1 month to finish bar
characterization
Station assembling will start in ~ 1 month. It
will take ~1 week per station.
small vessel 90% completed in Napoli
Mechanical Workshop. Assembly & welding
of the full two vessels system two expected
Domenico Di Filippo
DCS
A draft version of DCS specification for the CHANTI is ready and will be
in EDMS by end of the week.
Starting the next week I will be at CERN working on the DCS software.
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Domenico Di Filippo
High rate efficiency estimation
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We expect a mean rate of about 500 kHz on a single CHANTI bar
(see Marco Mirra talk at software meeting).
In order to get an estimation of the high rate behavior of the
CHANTI electronic we use BTF data taken last summer (analysis
performed in Michele Corvino B.Sc. Thesis work)
Flash ADC
Beam: 575 MeV eRate: O(Hz)
Multiplicity: O(1)
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e- beam
Tag1
5 Bar CHANTI
prototype. 2 channel
instrumented.
Tag2
Domenico Di Filippo
Emulating high rate with BTF data
Event #
Some events present two distinct peaks (they are not particle of same
burst because there are about 20 ns between them). Restricting our
analysis to these kind of event we can emulate high rates
Peak delay (us)
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Domenico Di Filippo
Efficiency on the 2nd peak
1st peak revelation efficiency; it is due to acceptance.
0.924
Dead time < 60 ns. We
(conservatively) estimate an
inefficiency of about 2%.
Peak Delay (us)
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Domenico Di Filippo
Tot Board
CAEN bus
over USB
(LVDS over HD cable)
Arbitrary
Waveform
Generator
HPTDC
Tot board calibration setup
(trigger)
VME Bus
( Thanks to Frascati
and F.Gonnella for the
TDC controlling
software )
PC (Linux)
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Domenico Di Filippo
Tot board calibration strategy
(base-Tot)*slope = Th_trail
(base-Tot)*slope = Th_lead
Trail threshold
Lead threshold
We first add a stable part
to the signal to not stress
the electronic
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100 ns
100 ns
147 mV
Domenico Di Filippo
Threshold calibration
Trail Threshold
Lead Threshold
Threshold (DAC count)
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Domenico Di Filippo
Hysteresis
Hysteresis
Reproducibility
Threshold (DAC count)
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Domenico Di Filippo
Signal width dependance
The CHANTI signal have not the flat region, so we want to check
the ToT behavior in more realistic condition
width
Trail Threshold
Lead Threshold
100 ns
There is an unexpected
width behavior.
Width (ns)
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Domenico Di Filippo
DC cut
Looking at the Tot 4-channel analog adder, it seem to be there a
sensible DC cut.
Big (in charge) signals get a (positive) offset, so we get a wrong
threshold estimation.
This could be a problem in high rate environment because the signal
mean charge could sensibly differs from zero.
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Domenico Di Filippo
Threshold (mV)
DC cut effect on CHANTI
We expect a ~500kHz
rate i.e. 2000 ns
period.
50 ns
Trail Threshold
Lead Threshold
100 ns
CHANTI working
point at ~6000
However we use a signal
with 3x the real signal
charge, so it is
comparable with 6000 ns
with real signals.
Period (ns)
So, this effect should be under control. More (direct) test soon...
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Domenico Di Filippo