p ierre colin dmitry naumov patrick nedelec
DESCRIPTION
RECONSTRUCTION OF EXTENSIVE AIR SHOWERS FROM SPACE. Stand alone method using only EAS induced light . General algorithms for any space project. ( EUSO, OWL, TUS, KLYPVE… ). P ierre Colin Dmitry Naumov Patrick Nedelec. Physics hopes. Purpose : Reconstruct initial UHECR parameters. - PowerPoint PPT PresentationTRANSCRIPT
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Pierre ColinDmitry NaumovPatrick Nedelec
RECONSTRUCTION OF EXTENSIVE AIR SHOWERS
FROM SPACE
• Stand alone method using only EAS induced light.• General algorithms for any space project.
( EUSO, OWL, TUS, KLYPVE… )
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Purpose: Reconstruct initial UHECR parameters
Energy (spectrum)
Direction (UHECR sources map)Particle type (proton, iron, neutrino, gamma, etc.)
Physics hopes
?
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Angles (Zenithal θ and Azimuthal φ)Altitude of shower maximum: HmaxDepth of shower maximum: XmaxTotal energy released E
Shower parameters
Hmax
Xmax
UHECR :
Direction
Particle type
Energy
E
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
UHECR
Detection from space
Extensive air shower
Air fluorescence (isotropic)
Space telescope
Cerenkov light(directional)
Ground scattering
Cloud
EUSO simulation
Fluorescence Cerenkov echo
SIGNAL = f(t)
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Data fit
fit: 2 Gaussians: Fluorescence + Cerenkov
+ constant: Background noise • Monte Carlo data
- Global fit Fluorescence Cerenkov Background
Available information: for every GTU (Time Unit ~2.5 µs) Number of detected photons: Ni
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
ReconstructionReconstruction
Get angles (θ,φ)
Get Hmax
Get Xmax
Get E
Monte Carlo Data
Signal analysis (Trigger conditions): 3 samples of events
Fluorescence events
Cerenkov events
Golden events
(Fluo+Cer)Reconstruction
Get angles (θ,φ)
Get Hmax
Get Xmax
Get E
TWO METHODS
Key parameterGolden eventFluorescence
event
Need Cerenkov echo
Only signal shape
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Hmax reconstruction : Cerenkov method
For golden events :
We use Cerenkov echo
: Time between Cerenkov and fluorescence maximum
(Classical method)
Disadvantage: We need to know Hcer to reconstruct Hmax
: Relief, Cloud altitude (Lidar?)
max
2
cos 2 1
H c c R
c R n
AAAAAAAAAAAAAAAAAAAAAAAAAAAA
x
y
z
EUSO
α
ΔH
Cerenkov echo
Fluorescence
R
maxn
AAAAAAAAAAAAAA
ΔH = Hmax - Hcer
ΔH Hmax = ΔH + Hcer
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Hmax reconstruction : Cerenkov method
Method not efficient for large angle (horizontal EAS)
Test of the method: no cloud events (Hcer = 0 )
Reconstructed Hmax vs Simulated Hmax Relative Erreur
Error<10% for <60°
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
(Brand new method)For Fluorescence event:
Hmax reconstruction : Shape methodF
luor
esce
nce
Yie
ld (
ph/m
)
We use only Fluo signal
NeL Y N
L= EAS track length
= # emitted photon
Ne = # charged particles in EAS
Y = Fluorescence Light Yield
Y: smooth variation with altitude
In one GTU i: Li = LGTU csteNi η·Y·Ne·LGTU = # detected ph/GTU
Ni is quite independent of the altitude: Ni
NeNmax (η·Y)max·Nemax
·LGTU
Transmission η has also a smooth variation with altitude
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Total shower lenght: L = LGTU = xtot / (h)
Ntot = Ni η·Y·< Ne>·L η·Y·<Ne>· xtot / (h)
Xtot = L·(h)
L20=100 km
Hmax reconstruction : Shape method
L5 = 15 km
5 km 20 km
For horizontal showers:
00
1 avec 8
( )
h
HtotN e H km
h
Ntot varies dramatically with altitude:
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Hmax reconstruction : Shape method
Approximation:<η·Y·Ne> = (η·Y)max ·< Ne>< (h) > = (Hmax)
Generalization for all angles :
(Hmax) Hmax
maxmax
max( )e GTU
tot e tot
N N LH
N N x
Nmax/Ntot (Hmax)
Thanks to η & Y smooth variation with altitude
Varies like ln(E)
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Hmax reconstruction : Shape method
Good Method to reconstruct large angle EAS !
Reconstructed vs Simulated Hmax Relative Erreur
Test of the method:
Error<10% for >60°
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Simulated Simulated
Direction reconstruction :
There is relationship between (i
x,iy) and (θ,φ) angle of EAS.
Rec
onst
ruct
Assuming infinite pixel resolution
Rec
onst
ruct
Θ
Available information: for every GTUPhoton incident angles: i
x, iy
Direction:
σ ~ 2°
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Xmax reconstruction
(reconstructed Xmax – simulated Xmax) (Θ) in g/cm2
Hmax by Cerenkov echo Hmax by shape method
σ<5% for <50° σ ~ 10 %
Golden events fluorescence events
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Energy reconstruction
m a x
m a x m a x4 et
N Y N L
m a xG I L m o d e l : 1 , 4 5 G e Ve
EN
E reconstructed by shape method (fluorescence)
for 1020 eV protonσ = 22%
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Shape method good for UHE neutrinos!
protons
neutrinos
Neutrinos create mainly horizontal EAS without Cerenkov echo.
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Conclusion
We can reconstruct any EAS : 0° to 90° or more ! This first trial is very promising.
We have developed two complementary methods to reconstruct EAS from space using UV light signal.
using Cerenkov echo• Efficient for “vertical” showers (<60°)• Need complementary information (echo altitude) using only signal shape• Efficient for “horizontal” showers (>60°)• UHE Neutrino astronomy from space is possible
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
BONUS SLIDE
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Simulated data
Available information: for every GTU(Time Unit ~2.5 µs)
Photon incident angles: i
x, iyNumber of detected photons: Ni
x
y
z
Space telescope
αx
αy
Extensive air shower
Hmax
ix, i
y EUSO simulation
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
If we add pixel resolution:
EUSO event on focal plan (M36)
Error : more from detector than from method
EUSO simulation
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Iron proton
SLAST simulation of Xmax(g/cm2)
Xmax reconstruction
Xmax change with RCUE type:
Xmax = f(E/A)(E/A is energy by nucleon)
Xmax for Golden events Xmax for fluorescence events
Test with 10 000 protons and 10 000 iron nuclei
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Energy reconstruction
m a x
m a x m a x4 et
N Y N L
m a xG I L m o d e l : 1 , 4 5 G e Ve
EN
Y : Fluorescence yield (ph/m) Kakimoto Model
η : Atmosphere transmission Lowtran Model
ε : Detector efficiency
ΔΩ : Detector solid angle
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
Energy reconstruction
XXXXeme Rencontres de Moriond Pierre COLIN March 2005
UHECR
Air scattering
Detection from space
Extensive air shower
Air fluorescence (isotropic)
Space telescope
Cloud
Cerenkov light(directional)
Ground scattering
EUSO simulation
SIGNAL = f(t)