![Page 1: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/1.jpg)
Diego González-Díaz (GSI-Darmstadt)
A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang (Tsinghua U.-Beijing), J. Wang (Tsinghua U.-Beijing)
Darmstadt, November 24th, 2009
one year ago
![Page 2: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/2.jpg)
Diego González-Díaz (GSI, TU Darmstadt, Tsinghua University)
Y. Wang (Tsinghua U.-Beijing), J. Wang (Tsinghua U.-Beijing),
C. Huangshan (Tsinghua U.-Beijing), P. Kowina (GSI), P. C. Huangshan (Tsinghua U.-Beijing), P. Kowina (GSI), P.
Moritz(GSI)Moritz(GSI)
and the NeuLand-R3B groupand the NeuLand-R3B groupDarmstadt, February 10th, 2011
now
![Page 3: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/3.jpg)
what has happened since?
![Page 4: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/4.jpg)
X workshop on Resistive Plate Chambers and related detectors Darmstadt, February 9-12, 2010.Sponsored by HIC4FAIR.
![Page 5: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/5.jpg)
1. RPC HADES-TOF wall cosmic ray test performance, A. Blanco.
2. FOPI MMRPC ToF barrel. M. Kis.
3. A multipurpose Trigger Readout board. M. Palka.
4. The Slow Control System of the HADES RPC wall. A. Gil.
5. High Resolution TDC ASIC for CBM-TOF, H. Flemming.
contributions directly connected to GSI
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1. Progress of R&D and production of timing RPCs in Tsinghua University, Yi Wang.
2. A prototype of high rate MRPC for CBM-TOF, J. Wang.
3. Ceramics high rate MRPC for CBM-TOF, L. Naumann
4. Towards a high granularity, high counting rate, differential read-out RPC. M. Petris.
5. The CBM Time-of-Flight wall. I. Deppner.
6. Progress in the simulation of Resistive Plate Chambers with multi-strip readout.
D.Gonzalez-Diaz.
7. NeuLand: MRPC-based time-of-flight detector for 1 GeV neutrons. D. Bemmerer.
8. Development of MMRPC prototypes for R3B, FAIR. U. Datta Pramanik.
9. Some results of the R&D of a ToF-wall to identify relativistic ions. E. Casarejos.
10.Design and construction of iToF: a ToF-wall detector to identify relativistic ions in
R3B, FAIR, E. Casarejos.
11.A closed-circuit gas-recirculation system for RPC detectors. D. Rossi.
12.NeuLand MRPC-based detector prototypes tested with fast neutrons. C. Caesar.
13.Testing timing RPCs at ELBE/Dresden using 32MeV single-electron bunches with
picosecond time resolution. D. Stach.
14.NeuLAND MRPC prototypes tested at ELBE/Dresden. D. Yakorev.
contributions directly connected to FAIR
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->28% of the workshop contributions were connected to GSI/FAIR.
->70% of the workshop contributions related to time-of-flight
((and)multigap, (and)multistrip) RPCS were connected to GSI/FAIR.
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R3B/itof (SIS100)
GSI-FAIR in a nutshell (as of today)
R3B/neuLand (SIS100)
CBM (SIS100/SIS300)
FOPI (SIS18)
FOPI (SIS18/SIS100)
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progress on the simulation and understanding of the counters
![Page 10: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/10.jpg)
The simulation scheme in a nutshell
generation + induction
1transmission
2
FEE response
3
multi-strip
4
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1. Dedicated measurements of transmission properties and benchmark of the electrostatic solver and modeling:
-Before: APLAC simulations(FDTD).-Now: MAXWELL-2D(FEM) + analytical solutions of lossy
telegrapher's equations.
2. Calculation of the induction profiles:-Before: analytical calculation (approximate).-Now: MAXWELL-2D(FEM). Analytical calculation used only for benchmarking the code.
3. Change of philosophy:-Before: work with induced charges (~slow amplifier).-Now: work with induced currents (broad-band amplifiers).
4. More realistic implementation of the Front End Electronics.
5. New parameters of the gas. MAGBOLTZ cross-sections re-obtained
to be consistent with 2009data for C2H2F4.
6. A simple parameterization of streamer formation introduced, based
on data.
7. Started porting the code MATLAB-based to C++ for usage in
FAIRroot both for R3B and CBM (~50% done).
What is new?
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1. Upgrades in signal transmission
transmission
2
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mg
mm
CC
C
L
L
0 mg
mm
CC
C
L
L
0mg
mm
CC
C
L
L
0
Experimental verification of electrostatic compensation
2m!
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Transmission characteristics in time-domain (I)
mg
mm
CC
C
L
L
0 mg
mm
CC
C
L
L
0 mg
mm
CC
C
L
L
0
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Transmission characteristics in time-domain (II)
mg
mm
CC
C
L
L
0 mg
mm
CC
C
L
L
0 mg
mm
CC
C
L
L
0
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figures of merit for typical signals
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transmission characteristics in frequency-domain
transmission
near-end cross-talk
far-end cross-talk
transmission (single-strip)
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possibly the most important figure of merit
the cross-talk to the over-next neighbor is the relevant figure of merit!
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The CBM-TOF wall. Design requirements
compensation for N-strips requires of the following conditions:
00 L
L
C
C mm 12 m
m
C
C
Diego Gonzalez-Diaz, Chen Huangshan, Yi Wang, arXiv.1102.1389
generally satisfied generally not satisfied
then all the system velocities become equal! (no modal dispersion)
details and proof in:
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induction
1
2. Upgrades on signal induction and charge profiles
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'Weighting field' technique for calculating induction profiles
analytic calculation MAXWELL-2D calculation
The analytical calculation usually fails in between strips
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induction
1
3. Upgrades on avalanche modeling
this part is still considerably behind the 'state of the art' simulations (the practical importance of a better modelization is not clear)
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Determination of C2H2F4 cross-sections from most recent data. MAGBOLTZ accuracy improved down to 1%. (S.
Biagi)
before
now
![Page 24: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/24.jpg)
Avalanche model constrained by world-wide survey
efficiency charge distribution
+ streamer parameterized in a crude way (when avalanche reaches a certain charge it 'explodes' into a streamer)
Diego Gonzalez-Diaz, doi:10.1016/j.nima.2010.09.067
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FEE response
3
3. Upgrades on FEE modeling
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Upgrades on FEE modeling (based on APLAC)
Modeling this is the weakest part so far. Requires hands-on work. Can not be modeled without detailed measurements. The main parameters of the electronics (threshold, gain) are now fixed to describe data
simplified sketch of the FEE developed by the RICE University (STAR)
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how does it look like?
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~centerof
strip
~regionbetween
strips
representation•gain=1•Vth equivalentat input
modestly fast~100evts/s
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some results
![Page 30: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/30.jpg)
multi-strip prototypes for CBM
![Page 31: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/31.jpg)
two selected chambers
24cm-long, 5x2(0.25gap)
1m-long, 6x2(0.22gap)
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charge distributionsTriggered events24cm-long, 5x2(0.25gap)
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Triggered eventscharge distributions
1m-long, 6x2(0.22gap)
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Triggered eventsand RPC firedcharge distributions
1m-long, 6x2(0.22gap)
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efficiency and cross-talk resolution
Global response
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efficiency profiles
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efficiency profiles (with ideal position information)
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multi-strip prototypes for R3B. Transmission.
D. Yakorev et al.submited to NIM A
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Global response. Electrons at ELBE (~mips).
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Outlook
●A MATLAB toolbox for fast RPC characterization is close to be finished. A fast scheme to simulate these counters has been implemented.
● With a larger scope, a software package is being created and integrated in FAIRroot. Results have not been presented here (see my talks at the last CBM collaboration meeting). The amount of work done, as compared to the MATLAB toolbox is ~50%. Speed is comparable, at present.
●Measurements on transmission and FEE characterization have to be done at least once, anyhow. Simulations are too much detail-sensitive. Simulations of this type will hardly replace measurements.
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Appendix
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-V
+V 1m
1m
the inocent problem
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-V
+V 1m
1m
I) a signal is induced due to the movement of the avalanche charges.The influenced area is very localized.
II) the signal must travel till the end of the structure
III) the signal must be measured at the end of the structure
Cg
CmLo
Lm
RR
?
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-V
+V 1m
1m
the signal starts moving
due to the mutual inductance a current of magnetic origin with opposite sign couples to the neighbor strip (Lenz law)
Cg
CmLo
Lm
RR
a signal is electrically coupled through the mutual capacitance, with equal strength for both ends
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xLxCxct mmIII ,,,
dt
dV
Z
LCI
c
mmxct
2,
dt
dVC
L
L
C
CI mm
xct 000
,
cmmxct Zdt
dIL
dt
dVCI
1,
2,
1
cmmxct Zdt
dVL
dt
dVCI
dt
dI
vL
L
C
CI mm
xct
1
00,
-V
+V 1m
1m
Cg
CmLo
Lm
RRx
after a series of 'minor' reasonable assumptions... (~usually termed 'low coupling')cIZV
00
1
CLv
0
0
C
LZc
summing up the contributionsof infinite C/L elements along the line
dt
dI
v
x
L
L
C
CI mmct
00
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dt
dI
v
x
L
L
C
CI mmct
00
increases with the unbalance between capacitive and inductivecoupling. It can change sign!
increases with the propagation distance
increases with the signal slope/rise-time
can we make this zero?
A rigorous derivation of the expression for Ict starting from the telegrapher's equations provides the same result in the low-coupling limit
![Page 47: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/47.jpg)
problem: inductances are not very intuitive for most of people
dt
dI
v
x
C
C
C
CI mmct
00
0
0
solution: a well known theorem relates the inductance with the capacitance matrixes of the structure in empty space (more intuitive, although not directly measurable)
when is this zero?. When the field lines couple through a single dielectric material.When it is zero we will say that the system is 'electrostatic compensated'.
r
000
0
CC
CC
r
mrm
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the basic questions:
is it possible to reasonably compensate an inhomogeneous structure?
2,r
3,r1,r
?4,r
even if we manage, can we compensate if we have more than 2 strips?
2,r
3,r1,r
?4,r
(for most RPCs, yes)
(for some RPCs, yes)
even if we manage, what happens if the system is lossy (R,G) ?
2,r
3,r1,r
?4,r
(quite ok, but be careful)R G
G
?000
0
0
C
C
C
C mm
?000
0
0
C
C
C
C mm
?000
0
0
C
C
C
C mm
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A multi-gap RPC in general. Here a differential RPC ('a la' STAR), just for the sake of 'electrical elegance'
Rin
standard PCBwith read-outstrips on oneside
HV insulatorwith Vbreak>10-15 kV
HV coating withR~100 MΩ/□
+V
-V
differential pre-amplifier
at least 4 gas gaps (~0.3 mm thick)
float glass
particle
*parameters not from STAR
![Page 50: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/50.jpg)
More electrical schemes are (un)fortunately possible
ALICE-LHC
V
-V
-V
STAR-RHIC
V
-V
V
HADES-SIS
-V
-V
FOPI-SIS
-V
V
all these schemes are equivalent regarding the underlying avalanche dynamics... but the RPC is also a strip-line, and this is manifested after the avalanche current has been induced. And all these strip-lines have a completely different electrical behavior.
-V
V
V
-V
V
S. An et al., NIM A 594(2008)39 [10]
!
HV filtering scheme is omitted
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Avalanche generation. A simple avalanche model
• The stochastic solution of the avalanche equation is given by a simple Furry law (non-equilibrium effects are not included).
• Avalanche evolution under strong space-charge regime is characterized by no effective multiplication. The growth stops when the avalanche reaches a certain
number of carriers called here ne,sat.
• The amplifier is assumed to be slow enough to be sensitive to the signal charge and not to its amplitude. We work, for convenience, with a threshold in charge
units Qth.
log 1
0 n e
lect
rons
~7
to t
space-charge regime
exponential-growthregime
~7.5
tmeas
avalanche Furry-typefluctuations
~2
Raether limit 8.7
exponential-fluctuationregime
threshold
0
simplifying assumptions
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Induction and weighting field Ez
(t)nedzvEti )( t=2.5 mm
w=22 mm HV
read-out
wide-pad limit t << w
gap
totz C
C
gE
1
additionally when g<<t (typicalsituation) Ez does not depend on the position –z- along the gap
g=0.3 mm
ws-s ~0 mm
T. Heubrandtner et al. NIM A 489(2002)439
We adapted to multi-gap the formulas from: problem: under-estimation of Ez
for large inter-strip separations
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Cross-talk in a 2-strip RPC modeled as a loss-less transmission-line (I)
om
mo
CC
CCC
om
mo
LL
LLL
om
moc ZZ
ZZZ
1ˆ TvTLZc
112 ˆ)ˆ(ˆ TLCTv
momo LLCC
20
02
vv
vv
v
cc
o
m
co
mc
c
ZZC
C
ZC
CZ
Z
roo
cCLv
1
)(3moom LCLCvv
cCC
LZ r
oo
oc
1
two different modes in the transmission line!. This causes 'modal dispersion' unless:
o
o
m
m
L
C
L
C true for
homogeneous transmission lines!
a 4-gap RPC seen as a transmission-line
om
mo
RR
RRR
dominated by skin-effect:small for typical dimensionsand rise-times
om
mo
GG
GGG
very small, due to the presence of gas and glass
)(ˆ CC
for typical materials (glass)
loss-less line!
W. Riegler, D. Burgarth, NIMA 481(2002)130 [12]see
if
1)
2) 0, mm LC
![Page 54: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/54.jpg)
)(]9ln22)(
[)(2 v
ztI
tv
z
v
v
RZ
RZtI o
rise
o
inc
inmtc
for exponential signals
)(4
)(2,1v
ztItI o
tc
low-frequency /small distance/ non-dispersivelimit
high-frequency /large distance/ dispersivelimit
1
rise
o
tv
z
v
v
1
rise
o
tv
z
v
v
small dispersion
very large dispersion
zo = position along the strip where the signal is induced
see also [12]
the 2 modes are fullydecoupled
Cross-talk in a 2-strip RPC modeled as a loss-less transmission-line (II). Limits.
in
mg
mm
c
m
mgc
mg
mm
mg
RZ
Z
CC
C
L
L
Z
Z
CC
LZ
CC
C
L
L
v
v
CCLv
det
det
0
0
0
1
0
2
2
1
)(
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History revisited: 1.6m-long 2-strip RPC (P. Fonte et al., 2002)
width = 5cm
strip separation = 1mm
glass = 3mm
gap = 0.3mm
length= 1.6m
![Page 56: Diego González-Díaz (GSI-Darmstadt) A. Berezutskiy (SPSPU-Saint Petersburg), G. Kornakov (USC-Santiago de Compostela), M. Ciobanu (GSI-Darmstadt), Y. Wang](https://reader038.vdocuments.net/reader038/viewer/2022103100/56649f2e5503460f94c48163/html5/thumbnails/56.jpg)
Cross-talk in Fonte multi-strip RPC
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Cg=521 pF/m
Cm=88 pF/m
Fct=50% !
BW=1.5 GHzRin=50 Ω
very dispersive!
experimental conditions:Π, E=3.5 GeV, low rates, trigger width = 2 cm
Fct=40%
'fine-tunning'
80%-90% measured cross-talk levels reproduced
Zc~13 Ω
transverse scan
Cross-talk in Fonte multi-strip RPC
HV=5.7 kV
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x10
->increase stripseparation
Cg
Cm
Δv/v
trise
Minimizing cross-talk (I)
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x6 /2.5
/6
->increase strip/widthseparation->reduce glass thicknessCg
Cm
Δv/v
trise
Minimizing cross-talk (II)
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x6 /2.5
/6
BW/10
->increase strip/widthseparation->reduce glass thickness->reduce band-width
Cg
Cm
Δv/v
trise
low couplinglow dispersion
Minimizing cross-talk (III)
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guard strip
->put guard strip
Cg
Cm
Δv/v
trise
Minimizing cross-talk (IV)
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not mirrored
->use only two electrodes
Cg
Cm
Δv/v
trise
(it flips!)
Minimizing cross-talk (V)
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not mirrored
coupling to PCB
->use only two electrodes->couple locally to groundCg
Cm
Δv/v
trise
low couplingNO dispersion
Minimizing cross-talk (VI)
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Minimizing cross-talk + detector response (I)
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x10
Minimizing cross-talk + detector response (II)
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x6 /2.5
/6
Minimizing cross-talk + detector response (III)
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x6 /2.5
/6
BW/10
Minimizing cross-talk + detector response (IV)
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not mirrored
coupling to PCB
Minimizing cross-talk + detector response (V)
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Ideal case: no cross-talk + perfect tracking
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'some' of the new CBM prototypes(preliminary short compilation)
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35-cm long wide-strip, mirrored and shielded
... ...
Zc~18 Ω
BW=260 MHzRin=100 Ω
Fct=11%little dispersive
experimental conditions:~mips from p-Pb reactions at 3.1 GeV, low rates, trigger width = 2 cm
Fct=19%
'fine-tunning'inter-strip regiondominated by trigger width
probability of pure cross-talk:1-3%
Analysis with high resolution tracking on-going.
transverse scan
Cg
Cm
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1-m long counter, 6-strip RPC, 12-gap, mirrored and shielded
... ...
experimental conditions:~mips from p-Pb reactions at 3.1 GeV, low rates, trigger width = 2 cm (< strip width)long run. Very high statistics.
No simulations available yet
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no double hitdouble-hit in any of 1st neighborsdouble-hit in any of 2nd neighborsdouble-hit in any of 3rd neighbors
1-m long counter, 12-gap, mirrored and shielded
No simulations available yet
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1-m long counter, 12-gap, mirrored and shielded
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conclusions and outlook
• Multi-strip design of timing RPCs at 1-m scale with acceptable cross-talk, small cluster size and small deterioration of time resolution seems doable.
• Further optimized structures based on simulations are on the way (Fct~1%).
• For making a multi-strip fully robust against streamer-crosstalk there is still a long way to go (maybe impossible).
-> Detailed optimization based on physics performance soon to follow. Then we will know if cross-talk is 'high' or not.
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Multi-strip-MRPC (MMRPC)
1.1 mm
Glass: ε=7.5, strip width = 1.64 mm, strip gap = 0.9 mm, strip length = 900 mm
1.1 mm
0.5 mm
0.22 mm
copper (20 μm)
8 gaps
The FOPI counter
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Induction. Example FOPI case.
n(t)dwvEtI )(
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cathode 150 anode 1
50
50
50
cathode 250 anode 2
50
50
50
cathode 350 anode 3
50
50
50
cathode 4anode 4 50
50
cathode 550 anode 5
50
50
50
Cross-talk in an un-terminated line
signal from BC420scintillator (used as current generator)
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cathode 150 anode 1
50
50
50
cathode 250 anode 2
50
50
50
cathode 350 anode 3
50
50
50
cathode 450 anode 4
50
50
50
cathode 550 anode 5
50
50
50
Cross-talk in a terminated line
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Cross-talk and signal shape
cross-talkconstant, very independent from the signal shape
low dispersion counter, typical working conditions, BW=260 MHz
Take as a typical shape the one of an avalanche produced at the cathode
Even for dispersive counters it is reasonable since most of the charge is coming from that region
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The FOPI counter (11th strip)
50 anode 0 50
50 anode 1 50
50 .......... 50
anode 11 50
50 anode 12 50
50
cathode
50 anode 13 50
50 anode 14 50
50 50anode 15
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The FOPI counter (9th strip)
50 anode 0 50
50 anode 1 50
50 .......... 50
anode 9 50
50 anode 10 50
50
cathode
50 anode 11 50
50 anode 12 50
50 .......... 50
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50-cm long, mirrored and not shielded
... ...
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~1-m long, non-mirrored and shielded
... ...
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several electrons (I)
•An ionizing particle at fixed energy creates an average number of ionizations no randomly distributed along the gap, with each cluster having a (1/ne in cluster)2 probability to produce more than 1 electron. This is very easy to generate. Then each cluster can be made to fluctuate according to Furry law.
HEEDcalculation
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A parentheses: rate capability of various CBM prototypes
for small fluxes and in a simple DC-model
gappergapper dqg
EE1
)(
see for instance: D. Gonzalez-Diaz et al. Nucl. Phys. B (Proc. Suppl.) 158(2006)111
dqAoTT ,)(
dqBo )(
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A parentheses: rate capability and DC-model systematics
In first order, it fits! dqAoTT ,)(
dqBo )(
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prompt (e-) component
Slow (ion) component
g/ve ~ 1 ns g/vi ~1 μs
E=ΔV/g
ev
D
/1
p
particle
e--I+
How (we believe) is the avalanche produced?
vtwo eEqti )(
ith
space-chargelimitation
Eav~E
avalanche growth
decreases!
τg ~ 1 s (glass relaxation time)
see [4],for instance
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First of all... what is a strip?
In this talk:
A strip is a read-out structure that must be described (due to the phenomena under study) like a transmission-line. In the simplest single-strip description, it is something characterized by 2 magnitudes: a transmission coefficient and a propagation velocity.
This is a definition based on the electrical properties of the structure.
In standard language:
- strip: something read-out in two ends/something 'quite rectangular'- pad: something read-out in one end/something 'quite squared'
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Induction + transmission + FEE. Sketch (II)
Five stages in order to get a predictive result
• Avalanche generation with the previous code.
[->Comparison with eff vs V and fine-tune, if needed, of threshold value. This approach seems to be flexible enough.]
• Induction, based on analytical formulas from [13], extrapolated to multiple-gaps by using the effective series permittivity of the corresponding group of layers.
• Propagation based on HF simulator APLAC (http://web.awrcorp.com/Usa/Products/APLAC/).
[-> Validation of APLAC for the structure of interest with a pulse generator (nowadays we do not need this step anymore)]
• Termination and other circuit elements are included, together with FEE, simulated also with APLAC.
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A 2-strip RPC as a loss-less transmission-line. Example (III)
2-strip geometry and signal taken from [12]
injected signal cross-talk signal
non-dispersive limit(zo=0)
dispersive limit (zo->∞)
->Continuous line is the exact analytical solution from [12].->Dashed and dotted lines are the numerical solution from APLAC used later in this work.
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Measurements of cross-talk with RPC mockup
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Typical plots where to look at
• Transverse profile of the efficiency, with and w/o valid charge.
• Cross-talk probability. Integral and as a function of the charge in the main strip.
• Resolution when a second hit is present in the module.
• Cluster sizes (not shown here).
• Dependence with HV of the above observables (not shown here).
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50-cm long wide-strip, mirrored and not shielded
... ...
probability of pure cross-talk: 1-3%
similar cross-talk levels than in previous case
experimental conditions:~mips from p-Pb reactions at 3.1 GeV, low rates,
trigger width = 2 cm (< strip width)
BW=260 MHzRin=100 Ω
Zdet~20 Ω
Cm=18 pF/m
Cg=276 pF/m
dispersiveCm/Cg =6.5%
Fct=11.5%
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30-cm long narrow strip, differential
... ...
Cm=20 pF/m
Cdiff=23 pF/m
Fct=9%
experimental conditions:~mips from p-Pb reactions at 3.1 GeV, low rates, high resolution (~0.1 mm) tracking
probability of pure cross-talk:1-3%
intrinsic strip profile is accessible!
Zdiff=80 Ω
dispersive
transverse scan