Study of cosmic ray shower front

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Study of cosmic ray shower front and time
structure with ARGO-YBJ
A. Karen C. M., Lorenzo Perrone
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NEW FEATURES Larger statistics simulations
Allows comparison of simulation to data
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Definition of observables
.from ICRC07

1. The curvature of the shower front as the mean of
   time residuals with respect to a planar fit (Td)
2. The thickness of the shower front as the root
   mean square (RMS) of time residuals with respect
   to a conical fit (TS)

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Definition of observables
.from Kascade-Grande
Shower axis - trajectory of the incident primary
cosmic ray particle towards the obervation
level Shower plane plane perpendicular to the
shower axis R radial distance from the shower
core
The shower disk refers to the curved disk of
secondary shower particles towards earth
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Mean arrival time vs distance to shower core
Thickness vs distance to shower core
.from Kascade-Grande
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Projection of R on the shower plane
? zenith and ? azimuth angles of the shower
Rotation of ? in the xy plane
Projection
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Shower Reconstruction
In EAS experiments for an event E the time tEP
can be measured on each fired detector unit P,
whose position (xP,yP) is well known
Primary direction cosines
Planar Fit
Conical Fit
This quantity is not a proper c2 . Indeed the
measurement unit is ns2
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Data Selection
Cuts used for ICRC07

• A successful reconstruction of the global shower
  observables is required
• Nhit gt 20
• Reconstructed shower core coordinates are within
  the central carpet
• Sub-sample well reconstructed days 006-007 2009
  (new data sample)
• Zenith angle less than 15

Room left for more accurate event selection and
quality cuts
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Data
Shower curvature
Mean of the time residuals (from Planar fit)
profile as a function of the core distance
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Data
Shower curvature
Mean of the time residuals (from Planar fit)
profile as a function of the core distance for
different pad multiplicities
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Data
Shower curvature
Mean of the time residuals (from Planar fit)
profile as a function of the core distance at
different multiplicities
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Data
Shower thickness
RMS of time residuals (from Conical fit) profile
as a function of the core distance
statistical errors errors on the mean
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Data
Shower thickness
RMS of time residuals (from Conical fit) profile
as a function of the core distance for different
pad different multiplicities
statistical errors errors on the mean
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errd0j(1-sqrt((entries0j-1)/((entries0j)(s
qrt(2(entries0j))))))RMS0jerrs0j(sqrt((
entries0j-1)/((entries0j)-(sqrt(2(entries0j
)))))-1)RMS0j
statistical errors errors on the mean
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Larger statistics simulations
Production of Corsika showers with Grid -
Corsika 6720 - SIBYLL as high energy interaction
model - FLUKA as low energy interaction model -
dN/dE E-1 300 GeV - 300 TeV - dN/d?
sin?cos? 0-45
August 2008 - December 2008
Used se ts.infn.it
Used ce pi.infn.it ba.infn.it na.infn.it
(only tested)? ihep.ac.cn (only
tested)? cnaf.infn.it (heavyly used)?
107 showers 2.3 Tera
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Generated Sample vs Energy-Zenith
100 TeV
10 TeV
1 TeV
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Processing through argog at CNAF
Generation area 200 200 m2 Each shower is used
up to 10 times after re-sampling the core position
Overall simulated data set 107 events
Argog processing time at CNAF 100 CPU 36 hours
Motivation cross checking the dependence on
hadronic models for the cross-section analysis
and time front structure
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Simulated Events vs Energy-Angle
100 TeV
10 TeV
1 TeV
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Usage of individual showers vs Energy-Angle
100 TeV
10 TeV
1 TeV
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Xmax from corsika fit to the longitudinal
profiles included in the produced corsika binary
files
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Summary
- The production on GRID relatively smooth (GRID
malfunctioning limited to short time windows) -
Problems with the time bomb'' implemented in
FLUKA. This periodically requires a new
installation if the production takes longer than
few months. (FLUKA doesn't distribute the source
code. No way to by-pass this feature'' in a
clean way). It makes almost impossible to
reproduce a given shower generated in the
past'' Common problem for several
experiments. The community is considering to
move to UrQMD . It behaves similarly as FLUKA
at least in the TeV range (Geisha is not
manteined any longer)?
Showers available at /storage/gpfs_argo1/Producti
on/MC/Corsika6.7201 2.3 Tb
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Simulation
Protons (E-1) Corsika 6720 SIBYLLFluka. ?
showers
ARGOG - area of generation 200x200 m2 130
cluster
                       Theta
0-15E(TeV)          0.3 -1 1-3
3-10        10-30   30-100 N_argog
1800000 840000 210000  270000     
285000                     
   Theta 15-30E(TeV)          0.3 -1
1-3 3-10        10-30  
30-100 N_argog 2700000 600000
210000  210000      135000                    
     Theta 30-45E(TeV) 
        0.3 -1 1-3 3-10  
     10-30   30-100 N_argog 2700000
600000 210000  210000      135000
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Xmax
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H1st
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Simulation
Shower curvature
Mean of the time residuals (from Planar fit)
profile as a function of the core distance at
different multiplicities
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Simulation
Shower curvature
Mean of the time residuals (from Planar fit)
profile as a function of the core distance for
pad different multiplicities
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Simulation
Shower thickness
RMS of time residuals (from Conical fit) profile
as a function of the core distance
statistical errors errors on the mean
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Simulation
Shower thickness
RMS of time residuals (from Conical fit) profile
as a function of the core distance at different
multiplicities
statistical errors errors on the mean
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Comparison data with MC
Zenith Angle distribution
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Comparison data with MC
Mean of the time residuals (from Planar fit)
profile good agreement between data and
simulation
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Comparison data with MC
Mean of the time residuals (from Planar fit)
profile good agreement between data and
simulation
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Comparison data with MC
Mean of the time residuals (from Planar fit)
profile agreement up to 60 m between data and
simulation
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Comparison data with MC
Mean of the time residuals (from Planar fit)
profile sensible differences between data and
simulation for lower pad multiplicities
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Comparison data with MC
nhit 100-200
RMS of time residuals (from Conical fit) profile
to be investigated
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Comparison data with MC
nhit 200-400
RMS of time residuals (from Conical fit) profile
to be investigated
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Comparison data with MC
nhit gt1500
RMS of time residuals (from Conical fit) profile
to be investigate
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Proton Shower
Photon Shower
Indicators for ?/hadrons discrimination density
lateral profile, alpha and RMS from the conical
fit and the deviation of time residuals from
planar fit at different cut of multiplicity and
angular range?
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Shower size at maximum is correlated with the
primary energy and can be used as energy estimator
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What else can we learn of shower phenomenology..
Observable
true value
Moderate correlation of conicity with Xmax for
protons
New fit with alpha free
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Whats more.