Prsentation PowerPoint

1
Electronic Design for a proton trigger and a
Time of Flight measurement with the Recoil
Proton Detector for the hadron program
Nicole dHose and CEA-Saclay (SPhNSEDI)
and Bonn, Mainz, Warsaw
(groups involved in the GPD recoil
prototype)
CERN, TB, 9 March, 2007
Freiburg, JRA5 meeting, FP6, 22 March 2007
2
Status of the present RPD
Electronics solution - readout time and
amplitude measurements
with standard COMPASS equipement -
proton trigger (coincidence A-B selection of a
proton)
3
Time of Flight concept
zB tB
tdoB
tupB
LB 106 cm thick.1cm
65cm
zA tA
tupA
tdoA
LA 50 cm thick.0.5cm Ltarget 40 cm
?3.5cm
beam
12cm
target
zB (tupB - tdownB) VB/2 LB/2 Coruptw
Cordowntw Offup-Offdown
tB (tupB tdownB)/2 LB/2VB Coruptw
Cordowntw OffupOffdown
To be precisely determined (tw time walk
correction)
Résolution on (tupB - tdownB) (with known
position) on (tupB
tdownB) (with known time or time of flight)

4
Objectifs in 2007 ? Objectifs in 2010
Recoil detector size 1m
size 4m
A 5mm B 10mm A 4mm B 50mm
Identification of protons reasonable
perfect
Proton Range in momentum 290 ? 800 MeV/c
270 ? 800 MeV/c in
angle 45 ? 90 36 ? 90
Resolution in ToF 300 ps
lt 300ps
Obtained results with the prototype in 2006 with
the MATACQ at CERN
at Saclay

• ?(tupB - tdownB) 200 ? 6 ps ?(tupB
  tdownB) 145 ps ? 10 ps
• ?(tupA - tdownA) 270 ? 6 ps
• ToF ? (tupB tdownB) - (tupA tdownA)
• 315 ? 12 ps
• to be still improved but

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Criteria for a ToF measurement
Required resolution 300ps
Time walk corrections
t


Thr0


Thr1


Thr2
15ns
5ns
Methods 1- Sampling of the
signal each ns (with MATACQ board) -
necessity if more than 1 hit - not yet
available 2- Time over 3 thresholds (Reiner G.s
idea) Amplitude measurement
Vmax
V
6
Expected counting rates in each scintillator
For the recoil foreseen in the GPD program
target 250cm acceptance from 15 to 90
in 5?108 ? / spill of 5s (100 MHz)
- counting 100 MHz in the total
acceptance (in 24 elts!) - (4
MHz?150ns) ½ of all the scintillators are
touched - the scintillators
have less than 4 hits in 150 ns
For the RPD
in the hadron program target 40cm with
same thickness acceptance from 42.5 to
90 in 5?107 ? / spill of 10s (5 MHz)

Reduction by a factor 200 for the counting rates
We can expect really less than 1 hit in one
scintillator in 50 ns Simulation in progress
with low threshold (300 keV)
7
Requirement for the hadron program a smallest
timing window for the trigger to reduce the rates
Pulse shape and timing
For the ring A
Simulation from Andrea Ferrero
The A downstream signal is nearly independent of
the vertex position The A
downstream signal is considered as time leading
in all the following coincidences
8
Pulse shape and timing
min max
P280 MeV/c ?0.286 90 t 62cm 7.2 ns
45 t 87cm 10.2 ns P750 MeV/c ?0.624 90
t 62cm 3.3 ns 45 t 87cm 4.6 ns
?1 90 t 62cm 2 ns
45 t 87cm 2.8 ns transit time in A t50/16
3.1ns difference timing along the target
in B t106/16 6.6 ns
t40/301.3ns
B up
B down
A up
A down
all the signals within 50ns and relatively
time correlated
9
Energy lost in the A and B scintillators
A thickness 5mm B thickness 10mm
Tests in 2001
protons

275 410 760 MeV/c
For protons
50mm thickness for B would have been necessary
for a better p/? separation
10
Energy lost in the A and B scintillators
Dynamical range In A From 1 to 20 MeV Max
attenuation factor 0.8 (?2m) ? detection from
0.4 to 20 MeV
ratio 50 In B From 2 to 40 MeV Max attenuation
factor 0.28 (?0.8m) ? detection from 0.28 to 40
MeV ratio 150 PMT
Output signal for A from 100mV to 5V
for B from 30 mV to 5V !!!
Any improvement in the B attenuation length would
be welcome
11
Energy lost in the A and B scintillators
Tests in 2001
protons
due to attenuation length EB ? (EupB
EdownB) or rather less rigorously, but easier
for electronics EB EupB EdownB

SAH
double threshold coincidence
EA gt SAHigh and EB gt SBLow or
EA gt SALow and EB gt SBHigh
SAL
SBL
SBH
12
Possibility for a trigger scheme and ToF
measurement
Splitter discriminator with CFD with
adjustable threshold adjustable
threshold
The time of all the coincidences is determined
by Aido and the resulting jitter has to be lt 3
or 5 ns???
The time dispersion due to the different
channels has to be lt 3 ns???
FPGA
Coincidence OR
ALow
AiL B2iH
Ai B2i
trigger
AiH B2i L
AHigh
12?3 OR
12?3?2 COINC
Many adjustable delay
CFD with adjustable threshold
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Possibility for a trigger scheme and ToF
measurement
The time of all the coincidences is determined
by Aido and the resulting jitter has to be lt 3
or 5 ns???
Splitter discriminator with CFD with
adjustable threshold adjustable
threshold
The time dispersion due to the different
channels has to be lt 3 ns???
Coincidence OR
FPGA
ALow
AiL B2iH
Ai B2i
trigger
AiH B2i L
AHigh
12?3 OR
12?3?2 COINC
ADC
TDC
B2ido
B2ido B2iup
Many adjustable delay
TDC
B2iup
CFD with adjustable threshold
analogic sum
ADC
Proton Trigger  in yellow 
A_down  has the smallest timing dispersion and is
time leading in all the coincidences. CFD to
still improve the size of the time window Only
Threshold on the Sum (BdownBup) to avoid the
huge pb of attenuation lenght Double threshold
(Low and High) on A and B to eliminate electrons,
pions 500ns time to deliver the proton
trigger (70m cables to the trigger barrack)
50ns before FPGA lt140ns for FPGA 30ns for
coinc beamproton 280ns cables

14
FPGA
AiL B2i-1 H
Ai B2i-1
AiH B2i-1L
AiL B2i H
Ai B2i
AiH B2i L
12 OR for the TRIG GER
AiL B2i1H
ADC
Ai B2i1
TDC
Ai1do
AiH B2i1 L
SAi1L
ADC
TDC
Ai1up
Ai1L B2i1H
Ai1 B2i1
SAi1H
Ai1H B2i1L
(12-2) ?2 lignes
Ai1L B2i2H
Ai1 B2i2
B2i-1
..
Ai1H B2i2 L
B2i-1do B2i-1up
ADC
TDC
Ai1L B2i3H
B2ido
Ai1 B2i3
Ai1H B2i3 L
10 other groups
B2iup
TDC
FPGA very compact solution

ADC
Control of these individual coincidences
..
B2i1do B2i1up
B2i1
(24-3) ?2 lignes .
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Tests on FPGA
Transit time and dispersion of the signal through
the FPGA
Test done at Saclay by Denis Calvet (DAPNIA-SEDI)
with a FPGA build from an evaluation kit using
Xilink Virtex 4 (FX60-10)
ns
Transit time 10ns -------
Dispersion 3ns without optimisation
Question what is the requirement for a maximum
dispersion of the trigger ??
Channel number
Test done also by Krzysztof Zarembas group in
Warsaw Same transit time 8.4 ns with Xilink
XC95144XL-5-TQ144
16
CAEN module V1495 general purpose VME board
Delay input-output 15ns Programmable with
Quartus Timing of individual channels can be
checked and optimized In the design phase The
dispersion can be larger due to the use of
several boards (for the total inputs)
Eric Delagnes (DAPNIA-SEDI) will get this VME
board at the end of March and begin further tests
17
Final selection, costs and planning
in preparation for Freiburg
F1 TDC multihit 4 or 5 (for ToT) catches with
mezannine 24 or 30 k
time for production ?
6months?? SADC 3 SADC modules

6 k
time for production ? Gesica
and shapers integrator for the
total amplitude measurement? to be
studied Discriminators 3 ? 72 14 modules
Lecroy 4416 for example? can be
borrowed from the CERNs pool 12 months
4 k Splitters analog sum

Mainz/Bonn CFD discriminator
integrated in the previous device ? ??
FPGA 1rst tests of the CAEN module V1495 at
the end of March 10 k

Saclay/Warsaw Which
standard CAMAC/VME , ECL/LVDS ??? ?
number of crates, translators, cables, connectors
???
50 k
Total costs between 60 and 100 k
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RPD read out done with Damien Neyret
in k - solution 1 1 9U VME crate
(needed ???), near MM rack or Silicon rack
10 or 0? 1 VME CPU (needed ???)
5? 4
Catches into new VME crate or into RICH-MaPMT VME
crate 24 16 TDC-CMC
H or FH? 4
TCS receivers they are no more built! 1
multiplexer
2? 3 SADC modules

6 1 Gesica
4 (Igor?) 2
Odin Slinks to be exchanged with HOLA
2 fiber pair links, in MM rack or Silicon rack
- solution 2 1 9U VME crate (needed ???),
near MM rack or Silicon rack 10 or 0? 1
VME CPU (needed ???)
5? 5 Catches into new VME
crate or into RICH-MaPMT VME crate 30 k 20
TDC-CMC
H or FH? 5 TCS receivers
they are no more built! 2 multiplexers 2 Odin
Slinks to be exchanged with HOLA 2
fiber pair links, in MM rack or Silicon rack

Total 50 k
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• Comments on the
  calibration methods
• with cosmics,
• with laser light distributed to each
  scintillator,
• with muon tracks of determined direction in the
  muon beam halo,
• with elastic events ? p ? ? p

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Rough calibration with a green Laser
illuminated a totaly diffusive sphere
n optical fibers connected to the centre
in each scintillator
to control easily the electronics and to get a
quick determination of timing offsets.
Necessity to put the connectors before wrapping
the scintillators
21
Study with cosmics at Saclay
µ
Ref1 Scint to study Ref2
PM
t ( tL ref1 tR ref1 tL ref2 tR ref2) / 4
- (tL sc tR sc) / 2
The resolution on t is s2 s ref 2 s sc 2

with s ref ½ s TOFref1/ref2
z ( tL ref1 - tR ref1 tL ref2 - tR ref2) / 4
- (tL sc - tR sc) / 2
22
Test bench at Saclay for the cosmics
calibration
We can test Protvino and Mainz scintillators
light guides PMTs
23
Our ultimate goal for recoil detector studies
study in details the shape of the analog signals
collected on a few inner and outer elements to
continue our study with a new generation of
MATACQ boards to sample the signal and quantify
the background (to be taken into account in the
splitter with an extra ouput) with the
hydrogen target, the hadron recoil detector and
the positive and negative muon beams
during one or two shifts

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