Particle Physics with High Energy Cosmic Rays

Mário Pimenta Valencia, 10/2011

Particle Physicse+

K+-

ee

u

bc

dt

s

γ, W+,W-, Z0 G1,, …., G8

H0 ?

Accelerators

Year of completion

Ene

rgy

(GeV

) The Large Hadron Collider (LHC)

~1930

~ 10 MeV

High Luminosity Sophisticated detectors

Central region Energy limited

14 TeV

Cosmic rays

Energy (eV)

Flu

x (m

2 sr

s G

eV)-1

LHC

Forward Region Extreme Energies

Small fluxes indirect measurements

John Linsley, 1962

100 TeV

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

Cosmic rays “rain”

P(Fe) Air Baryons (leading, net-baryon ≠ 0)

π0 ( π0 e+e- e+e- …)

π ± ( π ± ν ± if Ldecay< Lint )

K±, D. …

16

Shower detection

ΔX

Xmax = X1 + ΔX

Shower development

X1Xmax

em profilemuonic

profile

dXdX

dNe

E Ne

dXdX

dN

N

l

dxxlX0

)()(

South Hemisphere Area ~ 3000 km2

Nov 2009

60 km

Malargüe, Argentina

The Pierre Auger Observatory

24 fluorescence telescopes1600 water Cerenkov detectors

1.5 km

telescope building

“Los Leones”

LIDAR station

communication tower

telescope building

“Los Leones”

LIDAR station

communication tower

Ground array measurements

v ~ c

From (ni, ti):The directionThe core positionThe Energy

E.M. and signal at the SD

S(1000) contributions Individual time traces

Proton, ϴ =45º , E= 1019 eV , d= 1000m

The fluorescence detectors (FD)

The fluorescence detectors (FD)

The fluorescence detectors (FD)

Fluorescence detector measurements

Fly’s EyeE~3x1020 eV

)(tN

E Ne

The direction

Light profiles

(Xmax, Energy, …)

Xmax

A 4 eyes hybrid event !

Total Energy uncertainty: 22%

FD

SD

SD Energy Calibration

S38

Exposure

Auger has already more than 10 times the Agasa Exposure

AMIGA/HEAT 23.5 km2, 42 extra SDs on 750m grid (infill array) associated with 30m2 buried scintillators, 3 extra FD telescopes tilted upwards 30

E ~ 3 × 1017 eV with full efficiency

The results

Energy spectrum

Energy spectrum

Ankle

GZK like suppression !!!

p

2.7K

Δ

π

N

Kotera &Olinto

Energy spectrum (interpretation )

Dip (Berezinsky et al) :

p γ → p e+ e-

Spectrum of UHECRs multiplied by E3 observed by HiRes I and Auger. Overlaid are simulated spectra obtained for different models of the Galactic to extragalactic transition and different injected chemical compositions and spectral indices, s.

GZK:

p γ → → p N

Correlation with AGNs

28 out of 84 correlates

P = 0.006, f = 33 ± 5%Vernon-Cetty-Vernon AGN catalog

Closest (4.6 Mpc) powerful radio galaxy with characteristics jets and lobes, candidate for UHECR accelerationCen A

E> 57 1018 eV

But particles with the same rigidity (E/Z) follows the same paths !!!

Lower energies

No significant anisotropies

scenarios in which high energy anisotropies are caused by heavy primaries and having a significant light component at lower energies are disfavoured

Xmax distributions

ΔX

Proton cross-section

Slightly lower than expected by most of the models but in good agreement with recent LHC data.

If % p > 20%, % He < 25%

Xmax distributions

As the energy increases the distributions become narrower !!!

<Xmax> and RMS(Xmax)

Heavy nuclei ? Wrong Physics models ?

γFe p

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

: iron fraction ; (1-): proton fraction

But if just proton and iron …

<Xmax>

σ (Xmax)

: iron ; (1-): proton

Not possible to have just a two component model !

G. Wilk, Z. Wlodarczyk

Number of Inclined events Multivariate and Universality

A significant excess of Muons is observed that can not be explained by composition alone

N ~ E095

If just proton …

A dramatic increase in the proton-proton cross section around :

!!!TeV100s

R.Ulrich

Reduced statistics

The grey disk model J. Dias de Deus et al. Hep-ph:

80 % Increase !

Black Disk

R

Ω

A fast transition to the black disk at √s ~ 100 TeV can accommodate an ~ 80% increase in the total cross-section

Exotics @Auger….Low flux

Limited detector capabilities

But a unique energy window! Double Bangs

Cloudy day !!!

In favour of a Particle Physics solution

Ankle related to GZK if proton

No anisotropy at lower energies from Cen A region

A proton/iron model does not explain simultaneously the <Xmax > and σ (Xmax) data

The Nb of observed muons is quite above the expectations

The Nb of muons grows like what is expected for a single component composition

We do need:

Higher statistics to be able to perform more sophisticated analyses

An upgrade of Auger South to enhance at least the muon sensitivity covering the entire array

“autonomous”RPCs

0

5

10

15

20

25

0 200 400 600 800 1000 1200Time (hours)

Bac

kgro

und

C

urr

ent

(pA

cm

-2)

10

14

18

22

26

30

Tem

per

atu

re (

ºC)

0

5

10

15

20

25

0 200 400 600 800 1000 1200

10

14

18

22

26

30

Background currentBackground current converted to 23 ºCTemperature

At a constant temperature the current is stable, demonstrating the operation of the chamber at a very low gas

flow.

External view of the 0.5x1m2 prototype

Structure of the prototype

Generic RPC architecture

Background current at a gas flow of 1 kg/year of R134a.

Resistive Plate Chambers (RPCs) are rugged and reliable gaseous detectors, widely used in High Energy and Nuclear Physics experiments.- excellent time resolution- can be produced in large areas- cheap

Under an absorber ...

2 plane “telescope”To discriminate straight pointing trajectories from the shower axis

PMT µ e

µ e

“em” supression

1.20 m

0.10 m ~ 5o

An array of Geiger avalanche photodiodes

Measurement of a “Dolgoshein” prototype

PMT typ. peak PDE 25%

SiPM could reach ~60%

SiPM getting better (higher PDE, lower dark noise, lower crosstalk,…) and cheaper New packages (denser) being released

Zecotek array Hamamatsu array

Towards a FS with SiPM

1440 pixels, 4.5 degree FOV

FACTFirst G-APD Cherenkov Telescope

Collaboration LIP, Aachen, MPI, Granada, Palermo, to develop a SiPM based Focal Surface

Microscope view of a SiPM

SiPM 50 m

We are exploring the 100 TeV energy scale, well beyond LHC, and may be we are touching something fundamental!

Maximo Ave GAP 2011-090N in Golden Hybrid events

N ~ E094 ~ flat dependence with cos2ϴ

Not p

ublic

!!!

These data are not consistent neither with a composition change scenario nor with the EPOS enhancement mechanism

N in Kascade Grande

E ~ 1016-18 eV

Data lies between models expectations for p and Fe

<Xmax> from SD

Asymmetry of Signal risetime

<sec(θmax)> <Xmax> !!!

< sec(θmax)> (E)

t tt

z

Muon Production Depth (MPD)

Reconstruct the MPD from the measured time traces at each SD detectors

L. Cazon, R.A. Vazquez, A.A. Watson, E. Zas, Astropart.Phys.21:71-86 (2004)

L.Cazon, PhD Thesis (USC 2005)

Muon time delays

Geometric delay

Z

r c tg

All delays

z

rctg

2

2

1

500 m

Above 500 m the geometric delay is clearly dominant !!!

ϴ = 600

0o

“em” background

60o

If reduced by a factor ≈ 10 and if better time resolution

r > 500 m ???

Ө > 30o ???

E > 2 1018 eV ??? (cross-check with AMIGA)