Air shower physics
SHINE autumn school 27. 10. 2020 Felix Riehn Universidad de Santiago de Compostela / LIP
What are air showers?
Proton, 100 TeV (simulation)
Air shower == cascade of Particle interactions in atmosphere
2 Created by …? Cosmic rays
Astrophysics:
Origin of features ? Acceleration ?
direct I nd ire ct (a ir sh ow er s)
(Unger 2006)
Particle physics:
3 (Engel 2019) CRs through extensive air showers
air shower physics (want to know): CR interaction - Astrophysics (primary particle) Energy, mass, direction - Particle physics (primary interaction) multiplicity, cross section …
Observables ?? 4 CR air shower observables
* particles at (under)ground * energy deposit along path
5 Example: Pierre Auger Observatory
Both! (Hybrid measurement)
6 Related to primary? Air shower development: the start
CR particle
UHE interaction (~100 TeV)
● Hadronic!
● Exotic?
● Black holes?
● UHE secondaries (~100 TeV) Fireball? ● Chiral symmetry? ● Pions, kaons, charmed ...
● New (exotic) particles?
● Lorentz invariance?
EAS according to SM ?? 7 EAS according to the Standard Model
CR proton
Hadronic interaction:
Successive interactions: EM cascade hadronic cascade 8 EM cascade
Equal sharing of energy
All with same interaction Ionisation (continuous length Pair creation Bremsstrahlung energy loss) Multiplicity: 2
Until continuous energy loss dominant
Generation 1 ‘generation z’
Generation 2
Etc. 9 Hadronic cascade
CR proton Assume pions only
Equal sharing of energy
Multiplicity: fixed
(Matthews 2005)
Until pions likely decay
10 Hadronic cascade
CR hadron Assume pions only
All with same energy
Multiplicity: fixed
(Matthews 2006)
11 Primary mass dependence
Superposition
12 Summary: EAS according to the Standard Model
EM cascade hadronic cascade
Data...? 13 Measurement of Xmax and Nmu
Fix primary energy and compare
SM prediction
Post-LHC interaction models
14 EAS according to the Standard Model ?
Whats going on?
e
d
a
c
s a 1) First interaction
c
c i Beyond SM?
n
o
r
d
a h 2) SM predictions correct?
EM cascade
EM cascade hadronic cascade
15 Interactions in air showers
energy of last hadron interaction E FCC?
n
e
r
g
y
d
e
c p+Air
r
e
a
s
e
s
(Maris ICRC 2013)
16 A way to get more muons
increase
Also in pion+Air ? 17 Rho mesons in NA61
Model was build on NA22 data
Prediction for NA61!
Ultimate confirmation: Measurement of neutral pions! 18 Effect on muons in EAS
~40% increase 19 Muon data vs. post-LHC models
Universal rho meson enhancement. Probably overestimated.
SIBYLL-2.3d
Enhancement only in NA61
Close remaining gap → motivate larger * QGP effects? * Kaon interactions? 20 More from NA61
NA61 & Sibyll: * forward kaons, * forward antiprotons underestimated * central pions overestimated
→ work for post-NA61 Sibyll
So far:
Needed / Possible? : Diffraction in
21 BSM physics for the muon puzzle?
Fluctuations Originate in 1st interaction!
EM cascade hadronic cascade
SM predictions
BSM not needed! 22 Summary
* EAS produce more muons than anticipated by interaction model –> muon puzzle * Muon production in EAS sensitive to broad spectrum of particle interactions
* Probably no exotic physics needed to explain muon puzzle * More accurate implementation of SM physics needed (NA61,LHCf tunes) * More accelerator data to validate models needed (NA61: kaon interactions!)
23 Bibliography
24 25 Full shower
Profile: EM dominates At the ground: more mixed
26 Auger Event display
27