R Vazquez  Showers Signatures
Upcoming SlideShare
Loading in...5
×
 

R Vazquez Showers Signatures

on

  • 586 views

 

Statistics

Views

Total Views
586
Views on SlideShare
586
Embed Views
0

Actions

Likes
0
Downloads
0
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

R Vazquez  Showers Signatures R Vazquez Showers Signatures Presentation Transcript

  • Signatures for showers: Shower Characteristics R. Vazquez, USC Trasgo meeting, February 2010. Santiago de Compostela
  • Extensive Air Showers iniated by Cosmic Rays have intrinsic characteristics: Size, timing, energies, densities, and rates are intrinsic to the shower and must be taken into account in the design of cosmic ray detectors. The ability to determine physical parameters from extensive air showers depends on the correct interpretation of these characteristics. Arrival direction Energy Chemical composition Hadronic interactions
  • Cosmic ray showers: Heitler model Energy Number of particles Depth E 1 0 E/2 2 λ E/4 4 2λ After n steps Ec= E/2n 2n Xmax= n λ Then : Xmax = λ log(E/Ec) and N~E
  • This simple model works well even for realistic MC. If the multipliticy depends on energy µ = KE δ Then X max = A(1− δ ) log(E / Ec ) + B However: Assuming perfect scaling. -Only forward region is relevant
  • For a nucleus primary one may apply the superposition model Nucleus of energy E, mass A = A nucleons of energy E/A X max (E , A) = λ log(E /( AEc )) = λ log(E ) + B Hadronic model dependence Composition dependence J. Knapp
  • Number of charged particles as a function of energy Nmax ~ E Differences between composition and hadronic models
  • Kascade Auger Argo The altitude of the experiment determine the energy range!!!
  • Longitudinal profile Near the maximum fluctuations are smaller. Fluctuations do not scale with energy 15 % 4%
  • π0 →γγ Muonic component π± →µ ν π0 decay instantly π± continue the cascade N 2N N= total π0 π± 3 3 multiplicity N (1+ 2 N ) 3 3 π0 π± ( 2N ) 2 γ 3 N2 After n steps, charged pions decay N ± = ( 2N )n E 3 Where E c = n N N µ = ( E )1+ log(2 / 3 ) / log(N ) ∝ E β E c β ≅ 0.8 − 0.9 1− β β For nucleus N µ (E , A) = AN (E / A) = A E
  • Seen in realistic MC QGSJET Proton Slope ≈0.9 independent of θ
  • Casa-Mia Data AGASA
  • Lateral Spread of the Shower Shower shape depends on the development stage
  • t = log(x) y = log(E)
  • Timing For muons timing is well understood. It is related to the height production distribution <t> = 250 ns σ= 210 ns dN/dt ~ dN/dz But has an additional R dependence 1019 eV Protons <t> = 700 ns σ= 350 ns
  • Muon height production depends on the composition. It could be used, in principle, as a handle to determine composition. However fluctuations are large. Max = 306 gr/cms 1019 eV Shower Max = 337 gr/cm2 σ= 158 gr/cm2 @ 60 deg. Max = 448 gr/cm2 σ= 172 gr/cm2
  • For electrons, the arrival time distribution is poorly understood Structure on µs scale E=89 EeV Θ = 31 deg.
  • Timing II: Uncertainties Core uncertainties induce timing uncertainties For r ~ 1000 m h ~ 10 km d ~ 100 m
  • Relativistic effects A muon with E ~ 1 GeV has γ ~ 10 and 1-β ~ 5 10-3 Then after x = 1000 m Same effect for relativistic electrons
  • Rates Accidental trigger rate The rate of accidental triggers Assume a time window T, and a single station accidental rate of r is R ~ r2 T T must account for inclined shower, for instance T~ d/c The flux of random muons is given by Φ ~ 100 1/(m2 s sr) Then R ~ (Φ A)2 d/c for A ~ 1 m2 d ~ 100m R ~ 300 events/day
  • dN = KE −γ dE γ~ 2.7 Cosmic ray spectrum compilation
  • Rates F ~ E-γ+1 The shower rate is given by R ~ Flux d2 R = B E-γ+1 d2 R ~ 7.4 108 1/s (Eth/1 GeV)-γ+1 R ~ 4 103 events/day Eth = 106 GeV R ~ 80 events/day Eth = 107 GeV