LAV trigger primitives
Francesco Gonnella
Photon-Veto Working Group
CERN – 09/12/2014
LAV primitives working principles
LAV12

256 lead-glass blocks

2 threshold for each block:
512 channels into one TEL62
PP firmware

Seeks coincidences (~6 ns programmable) between high and low threshold

Coincidence => slewing correction, primitive production


Possibility of asking a trailing on high and/or threshold crossing and a minimum ToT value to produce
a primitive
No coincidence => discard the hit
SL Firmware

Sorts and merges hits

Merges any hits within up to 25 ns (programmable)

Outputs the L0 primitives
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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What to do with trigger primitives?
 Trigger primitives are triggerless data coming from LAV12

Data must be very simple: hit time (40bit LSB=100ps) and primitive ID

Primitive ID represents the number of hits in the primitive cluster

4 programmable thresholds define the number of hits e.g.:

ID 0x11 -> less than 2 hits (i.e. one hit)

ID 0x12 -> less than 4 hits

ID 0x13 -> less than 10 hits

ID 0x14 -> more than 10 hits
 With minimal effort, data may be collected from all LAV stations
 Beam monitoring

The “famous” 100Hz structure of the beam was observed for the first
time in LAV trigger primitives
 Digital L0 Trigger
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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LAV firmware on CHOD
 The LAVFEE board used for CHOD
provides 8 analogue sums, on for
each quadrant (H and V)
QV1
QV2
LAV FEE
Analog sums
QV3
QV4
LAV FEE
QH2
8 ns
Discriminator
+
Amplifier
QH1
 8 channels are connected to an
independent TDC board, again
through a LAVFEE board:
V Plane
LAV FEE
LAV FEE
20 ns
H Plane
TEL62
QH3
QH4
LAV FEE
16 channels per quadrant
NIM
Logic
LAV
Firmware
Primitives

4 sums of horizontal quadrants

4 sums of vertical quadrants
 LAV firmware is adapted to look
for coincidences between
corresponding horizontal and
vertical quadrants
 This is done connecting the
Vertical Quadrant as “low
threshold” and the Horizontal
Quadrant as “high threshold”
 Horizontal-Quadrant signals were
artificially delayed to assure that
they come after the vertical ones
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Beam monitoring
 Primitive Ethernet cable are
connected from LAV12,
MUV3, and CHOD to Torino
L0TP
 Thanks to three Ethernet
switches primitive data are
duplicated and are
sent to a pc in the EB
 Primitives are acquired and
raw data are stored

MUV3 LAV CHOD
The PC can receive primitives
from any detector connected to the NA62 network
 A program has been developed to decode raw
primitive data.
 An online monitor software is used to produce
histograms
 These histograms are periodically sent to beam
experts in order to study the fine structure of the
beam.
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Burst profile
25ns
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Fine time burst structure
25ns
~10 ms
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Initial spike
25ns
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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LAV-CHOD comparison
LAV
CHOD
25ns
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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LAV-CHOD burst fine-structure
LAV
CHOD
25ns
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Fine structure average ~30 bursts
 The burst fine-structure looks somehow coherent among
different bursts…
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Conclusions
 Trigger primitives were never used for trigger generation during this
run
 A lot of debug has been performed and now LAV firmware is quite
reliable
 Nevertheless LAV rpimitives have been very useful for the beam
monitoring to spot the beam fine structure (NA62 readout is not
designed to cope with such an instantaneous rate at nominal
intensity)
 We have just started a series of tests of trigger generation with
primitives (without beam)
 First results were obtained yesterday evening and they seem to be
promising
 During the last days of the run, trigger generation with LAV
primitives will be tested with L0TPs (Ferrara and Torino)
Francesco Gonnella - Laboratori Nazionali di Frascati
09/12/2014
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Thanks for your attention
[email protected]
09/12/2014
Francesco Gonnella - Laboratori Nazionali di Frascati
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