LAV front-end board test
Silvia Martellotti, Francesco Gonnella
Photo Veto Working Group
3 September 2014
Silvia Martellotti - Laboratori Nazionali di Frascati
1
ToT mezzanine card (16 x)
2 channels and 2 threshold per
board.
Includes the circuits for: Clamp,
Amplifier, Comparator & LVDS
driver.
32ch
OUT
LVDS
16ch IN
Analog
32ch
OUT
LVDS
16ch IN
Analog
VME custom
power
CANopen
or USB
IN OUT
LAV front-end 9U board
Sum mezzanine card (16 x)
Sum 4 analog channels (8 x)
Sum 16 analog channels (2 x)
Connected to a 50W LEMO out
Test pulse controller (1 x)
Can set for each channel:
Pulse height (set/read)
Pulse width (set/read)
Pulse rate (set/read)
Board controller (1x)
Communicate using CAN or USB
Allows setting and reading:
Thresholds (set/read)
Power connection (read)
Inputs
Type
Outputs
Type
Power connection
VME J1
64 LVDS output
2 x SCSI2
32 analog signals
2 x DB37
8 analog sums of 4 ch
8 x LEMO-00
2 analog sum of 16 ch
2 x LEMO-00
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
2
LAV front-end electronics
LAV electronics channel working principle
to analog sum
LVDS
Low
threshold
Split
Amp 6x
Compare
To TDC
High
threshold
LVDS
Clamp
To TDC
 Split the input signal into two copies: 1 copy to comparator + 1 copy
to analog sums
 Clamp the signal preserving its width, wide dynamical range is
expected (MIP 70 MeV ~ 10 mV, high energy γ ~ 1V)
 Amplify the signal and compare with 2 thresholds
 Each threshold is independently adjustable up to 250 mV
 Produce an LVDS signal and send the signal to the digital read out
board
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
3
Test setup
 Hardware setup
Hardware layout
x2
x 16
x 16
32 ch
32 ch
TDC
CAEN
V1190B
VME
VME
Bridge
V1718
Linux
PC
GPIB programming
 Software flaw chart
repeat
n times
Repeat
n’ times
repeat
n times
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
4
Test stand at CERN
 The LAV front-end electronic test
stand has been moved to CERN to
allow in situ calibration and testing
of the boards
 Test of all the 86 boards have been
performed at CERN by F. Gonnella,
V. Kozhuharov, S. Martellotti, M.
Moulson
 The facility will be also used to
characterize the boards we have
provided to CHOD and CHANTI
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
5
Board modification is done
 All modified boards have been delivered, mounted and tested.
 5 boards have problems, 1 is still in Frascati




83/89 boards are ready
81/81 are installed
we have only 2 fully working spares
Investigations to fix problems on the remaining 5 spare is ongoing
Thanks to Katelyn Fariss and
Mia de los Reyes!
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
6
Hysteresis (histə’ri:sis)
 Time of threshold is measured with two different pulse setups:
5ns
20ns
20ns
20ns
20ns
5ns
threshold
 The mean values of the ToT distributions in the two setups are evaluated
 Hysteresis is evaluated with the following formula:
h=
DToT
DToT
1mV
=
= DToT ×
Slope1 - Slope2 20ns - 5ns
1ns
15mV 15mV
 Note that this strategy does not imply any knowledge on the threshold.
Francesco Gonnella - Laboratori Nazionali di Frascati
11 February 2014
7
Hysteresis
 The hysteresis has
been correctly
modified
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
8
Threshold offset
 The new
threshold offset
is lower
 we gain some
mV in sensitivity
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
9
Threshold offset channel by channel
 The offset is independent from the channel number
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
10
Calibration slope vs channel
 The amplification is dependent on the channel number,
i.e. on the track length
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
11
Calibration-line slope
 The calibration-line slopes were not altered by the hysteresis
modification
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
12
Strange Time-over-Threshold
 In few channels we have a peculiar ToT
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
13
Time resolution
 The time resolution is not effected from the hysteresis
modification
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
14
Time resolution vs channel
 There is a clear dependence of the time resolution on
the channel number and not on the mezzanine. This is
under investigation.
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
15
Efficiency drop
 Before hysteresis
modification: there were a
drop in the efficiency
curve for 18% of channel in
leading only and 20% of
channel in leading and
training
 After hysteresis
modification: the drop in
all the efficiency curves
disappeared!
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
16
Conclusions
 Boards were modified, re assembled and tested in time
 We have 81/81 installed boards and 2 spares
 We will work to repair the 5 boards with some problems
 The performance is improved, not only the hysteresis:

Efficiency drops disappeared

We can now safely go down in threshold to 5 mV
(even 4 if we smartly swap high and low threshold)
Silvia Martellotti - Laboratori Nazionali di Frascati
3 September 2014
17
Thank you for your attention
3 September 2014
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