INSTITUT NATIONAL DES SCIENCES APPLIQUÉES DE LYON - FRANCE INSA Lyon.
Emulsion Simulation Y. Caffari (IPN Lyon) F. Juget (IPH Neuchatel) A. Marotta (CNRS-IN2P3 Lyon) CERN...
-
Upload
coral-hunt -
Category
Documents
-
view
215 -
download
0
description
Transcript of Emulsion Simulation Y. Caffari (IPN Lyon) F. Juget (IPH Neuchatel) A. Marotta (CNRS-IN2P3 Lyon) CERN...
Emulsion SimulationY. Caffari (IPN Lyon)
F. Juget (IPH Neuchatel)A. Marotta (CNRS-IN2P3 Lyon)
CERN 3-5/05/2006
Outline ORFEO development program Event simulation for algorithm
comparison Event simulation for data/MC comparison Electron data/MC comparison A new effect of the reconstruction seen
in the data/MC comparison that must be simulated
Outlook
ORFEO development program
The next version of ORFEO will work under the new general simulation framework (OpRelease);
The ORFEO version actually on the web (working with OpRoot) has been validated (micro-tracks, smearing…) update to the simulation procedure and new packages (to add
new features and reproduce effects not related to physics or to emulsions) will be tested under this version till the new one will be fully operative;
The OpRelease framework has 3 working possibility: full detector+rock, full detector, single brick;
The ORFEO smearing features are implemented in OpRelease;
A new simulation of the brick structure (CS doublet, packing… ) is under development;
A package to read the new output (in the official OpRelease format) and process events with the emulsion reconstruction program will come soon;
A I/O package to reproduce the old output will be provided too for back compatibility.
Event simulation for algorithm comparison
The algorithm comparison is performed by using the simulated data stored @ http://ntslab01.na.infn.it/opera_sim/ORFEO_production/ ;
The default parameters are chosen in such a way to be in “reasonable agreement” with the OPERA test beam data BUT they are not supposed to be used for data/MC comparison; in
fact, in such a case a “good” data/MC agreement is not expected; The efficiencies are parameterized by using the reference brick
Actually, this parameterization does not fit with the efficiencies parameterized in the other tests beam made, so in data/MC comparison a parameterization obtained from data should be used;
The micro-tracks smearing, in position and angle, are obtained by using a 2 points simulation of the micro-track (see next slide) x=0.25 micron, y=0.25 micron, z=2.5 micron; These values should be tuned in the case of data/MC comparison;
2 points simulation of a micro-track
10. GeV muons y2
x= x1 +x2 - y= y1 +y2 - z= z1 +z2
)tan()cos()tan()cos(
)tan()cos()tan()cos(
0
0
z
z
Sxzz
zzz
ySy
Sxzz
zzz
xSx
y1
z1
x2
z2
x1
z
0
00
2220
2220
)tan1(
)cos()sin(
)sin()cos(
LT
L
zLL
T
L
SSS
SS
SySxS
SySxS
By taking into account that dx and dy are statistical errors gaussian distributed and dz is a maximal error with a flat distribution, these assumptions automatically give the expected dependences on :
“Since the base-tracks are constructed by using the 2 points at base, the same results are obtained for free for base-tracks too”
Transversal and longitudinal resolution
for simulated 10.GeV pions at =0.7 mrad
SlopLong1=0.037
SlopLong2=0.037
SlopTr1=0.008
SlopTr1=0.008
Smearing parameters are: Sx=0.25 micron, Sy=0.25 micron, Sz=2.5 micron.
Emulsion simulation for data/MC comparison: Event generation
Event generation in the ORFEO official version: Actually is used a modified version of OpRoot/Geant3
(the modified files are provided with the ORFEO tar file); The cut on the micro-tracks minimum energy is
removed; A smallest propagation step (as respect to the official
OpRoot) is used to reproduce the correct Moliere radius (as suggested in the Geant3 manual);
The compton production is on; To simulate a test beam: the beam momentum,
particles density and slopes can be chosen by using the standard OpRoot Config.C file.
Emulsion simulation for data/MC comparison: micro-tracks
digitization The micro-tracks digitization takes into account:
Position and angle micro-tracks smearing performed with the 2 point micro-tracks simulation.
The smearing parameters must be tuned to reproduce test beam data! The micro-tracks efficiencies (that must be parameterized from data) The micro-track number of clusters is assigned on a statistical basis.
A parameterization of the number of clusters as seen in data is needed;
Affine transformations between plates can be simulated To take into account the up-down link efficiency, the same
up-down linking algorithm used for real data is used to select the couples of micro-tracks that will survive after the linking.
Data vs MC: Pions 4 GeV The events were generated with
OpRoot The smearing parameters are:
Sx=0.25 micron, Sy=0.25 micron, Sz=2.5 micron.
these value are the same used for all the “official” productions
NO parameters optimization was made for this set of data.
TRIGGER
MC Tx=0.0055
MC Ty=0.0029
data Tx=0.0053
data Tx=0.0022
Slopes resolution(Tmicro-Tbase)
Tx-Tx1=0.01
Ty-Ty2=0.01
Ty-Ty1=0.01
Tx-Tx2=0.01
Tx-Tx1=0.009
Tx-Tx2=0.01
Ty-Ty2=0.009
Ty-Ty2=0.009
MC data
eCHI2P vs PHThis is the results of the micro slopes resolution simulation (eCHI2P) and of the
micro pulse height parametrization (bt PH)
bg rejectedMC Data
Base Track angle resolutionBin(i-1)=T(i)-T(1), i>1
MC Data
TxMean=11.5RMS=5.3
TxMean=11.7RMS=5.3
TxMean=11.2RMS=5.3
TyMean=11.4RMS=5.2
Base Pulse and eCHI2P
MC PHMean=26.6RMS=2.9
data PHMean=26.6RMS=3.0
MC eCHI2PMean=0.7RMS=0.5
data eCHI2PMean=0.8RMS=0.8
Number of segments followed without propagation (strongly related to micro track efficiencies)
Data
MC+eff.Assuming eff.=84.%
(84.% at theta<0.1mrad measured data)
MC: no correlation betweenMicro tracks momentum and pulse height by construction
Pulse height vs plate number
and energy loss
Data
MC
The events were generated with OpRoot The smearing parameters are:
Sx=0.4 micron, Sy=0.25 micron, Sz=2.5 micron.
(these value were obtained with a tuning on the data) Eff. Measured in the empty brick by using
cosmic muons Pulse Height parametrized by using the data
in the empty brick;
Data vs MC:Electrons 6 GeV
TRIGGER
MC Ty=0.0025
data Tx=0.0037
data Tx=0.0022
MC Tx=0.0043
Slopes resolution(Tmicro-Tbase)
Tx-Tx1=0.013
Ty-Ty2=0.007
Ty-Ty1=0.008
Tx-Tx2=0.014
Tx-Tx1=0.014
Tx-Tx2=0.014
Ty-Ty2=0.008
Ty-Ty2=0.008
MC data
eCHI2P vs PHThis is the results of the micro track slopes resolution simulation
(eCHI2P) and of the micro track pulse height parametrization (bt PH)
bg rejectedMC Data
MC vs data comparison
Selected tracks characteristics: The track starts in the 1st plate; Number of segments [3,15] ; The track is in a box with a
surface of 1.8x1.8cm2; The first segment of the track
is in a cone around the beam direction with open angle defined by the beam width;
YesNO
Base Track angle resolutionBin(i-1)=T(i)-T(1), i>1
MC Data
Base Pulse and eCHI2P
MC PHMean=26.4RMS=3.0
data PHMean=26.3RMS=3.0
MC eCHI2PMean=1.2RMS=0.9
data eCHI2PMean=1.1RMS=1.0
MC: no correlation between Micro tracks momentum and pulse height by construction
Pulse height vs plate number and
energy loss
Data
MC
about efficiencies… Brick not exposed
to the e beamReference brick eff.
Eff lead MC pionsEff no lead MC pions
Number of segments followed without propagation (strongly related to micro track efficiencies)
Data
MC without Efficiencies micro track
rejection
Eff. As measured inEmpty brick
(only cosmics exposition)
MC+eff.
A new effect of the reconstruction seen in the data/MC
comparison that must be simulated The effect as it was seen in the data and
in the MC; The source of the effect (as suggested by
Cristiano Bozza); Looking for a threshold effect in the
data…; Our suggestion for an upgrade of the
simulation procedure; A set of test that we need/suggest;
The effect seen in the data/MC comparison
Frederic
Yvan
The effect seen in the data/MC comparison
Blu real dataRed simulation
The effect seen in the data/MC comparison
Blu Geant4Red Geant3Green real data
The effect seen in the data/MC comparison
Blu real dataRed simulation
The source of the effect
“ When SmartTracker7 finds that two micro-tracks have one grain in common, only the one with more grains survives, and the other is discarded… …Background can “kill” good tracks (e.g. a Compton electron might “cross” some good track, “eating” its grains), and this is not obtained by just adding background to MC data at a micro-track level.”
(From an email of C. Bozza)
Looking for a threshold in the data…
the plot of the minimum distance between micro-tracks in a view will give us the real dimension of the “problem”. Coming soon…
Our suggestion for an upgrade of the simulation procedure.
A transversal dimension must be added to the micro-track
this will introduce a threshold effect… related to the cluster size, function of the energy…
If the distance between 2 micro-tracks at fixed z is less then the threshold, a function f(nc1,nc2) will help to decide if 1 micro must be rejected
In such a way the effect is additive in fact by adding the bg micro-tracks the overlap
probability will increase!!!
Tests program All the tests should be done on both oil and dry
objective and for different configuration parameters (grey level…)
From any test beam: Measure of the threshold (minimum distance between
micro-tracks couples in a view); …
From e test beam: Cluster size dimension as a function of the energy
(number of plate…); …
From test beam: Number of times that the first base-track of a secondary
track is seen as a function of the distance of the primary vertex from the lead surface;
…
Conclusions The emulsion simulation package (ORFEO) is
going to be fully implemented in the OpRelease framework;
2 different simulation procedure for algorithms comparison and for data/MC comparison defined;
A new tracking effect was seen in data/MC comparison. A procedure to reproduce it in the simulation is
under development; Some tests on data are needed to improve the
simulation properly.