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Report on UHE cosmic rays WG. Piera L. Ghia IFSI-INAF, Torino, and LNGS-INFN, Assergi, Italy Tom Gaisser University of Delaware, USA. TeV Particle Astrophysics II University of Wisconsin, Madison. What we had in mind :

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report on uhe cosmic rays wg

Report on UHE cosmic rays WG

Piera L. Ghia

IFSI-INAF, Torino, and LNGS-INFN, Assergi, Italy

Tom Gaisser

University of Delaware, USA

TeV Particle Astrophysics II

University of Wisconsin, Madison

slide2

What we had in mind:

Experimental overview over all the spectrum (from direct measurements up to highest energies/EAS indirect mea)

Theoretical point of view

CR interactions in the atmosphere

Direct meas

(balloons/satellites)

EAS meas

Interaction in air

CR WG Summary

theoretical point of view
Theoretical point of view

CR interactions

Came “for free” in the plenary session (P. Blasi, Open problems on the origin of cosmic rays) & S.Yoshida (EHE signals)WG: Acceleration at astrophysical shocksP.Blasi

S.OstapchenkoN. Solomey (MIPP)+G. Catanesi (Hadroproduction @ CERN, plenary)

CR WG Summary

slide4

Experimental status of the art

From PeV to EeVA.Haungs

Direct Cherenkov @ kneeS.Wakeley

Around and Above EeVB.DawsonC.FinleyM.TeshimaJ. Cronin (PS)Bai, Gaisser et al (poster)

Direct measurementsS.Swordy

CR WG Summary

slide5

Below the knee

Lower end of the spectrumDirect measurementsS.Swordy

CR WG Summary

slide6

CR history

ACE (Advanced Composition Explorer, NASA, 1997-2000) measurements: CR materials & history (400 MeV energy range)

CR lifetime from mea of secondary radionuclides (10Be, 26Al, 36Cl, 54Mn, and 14C)

Time between nucleosynthesis and acceleration

Isotopic abundances

CR WG Summary

S.Swordy

slide7

CR lifetime from meas of secondary radionuclides:

Namely, from the abundances of radioactive secondaries with t comparable with confinement time, relative to primaries

t=15±1.6 Myr

CR WG Summary

S.Swordy

slide8

Time between nucleosynthesis and accelerationand isotopic abundances

Decay 59Ni to 59Co by electron capture. Cannot happen if the parent has been accelerated (electrons stripped off)

ACE data indicate that the decay has happened -> time > life time of 59Ni has elapsed before acceleration (>7.4 104yrs)

CR isotopic abundances ≈ 400 MeV/N very similar to Solar System

But notable difference for 58Fe (excess due to Wolf-Rayet ejecta?)

CR WG Summary

S.Swordy

slide9

Below the knee

Towards the kneeDirect measurementsS.Swordy

CR WG Summary

slide10

H and He spectra

Thin calorimeters (JACEE, RUNJOB, ATIC)

Differences here: He intensity larger for Jacee than Runjob

Magnetic spectrometers (AMS, BESS, CAPRICE…)

Same magnetic rigidity spectra (parallel with E), power law

CR WG Summary

S.Swordy

slide11

Heavier elements and composition

Up to 1000 TeV/n

Runjob: constant

(but Jacee: mass increase towards the knee)

Tracer (heavy nuclei), magnetic rigidity spectra, consistent with Runjob

CR WG Summary

S.Swordy

to go further towards the knee ultra long duration balloon flights cream
To go further towards the knee:Ultra long duration balloon flightsCREAM

S.Swordy

Oxigen

Carbon

CR WG Summary

slide14

I knee

Questions:

Knee position

Composition @ knee

CR anisotropy

Spectrum structure

CR WG Summary

A.Haungs

slide15

Experimental answers

Studies on spectrum/composition from Kascade, EAS-TOP, Tibet Asg, Ooty…

CR WG Summary

slide16

Kascade

Analysis depends crucially on interaction models

Unfolding performed for

Different interactions models (Sybill, QGSJET)

Different low energy interaction models (Gheisha, Fluka)

CR WG Summary

A.Haungs

slide17

Kascade

Knee @ 5PeV

A.Haungs

CR WG Summary

slide18

Tibet

Tibet results

Proton and Helium do not bend at the knee (already steeper than direct meas.)

Fraction of nuclei heavier than He increases with E at the knee

Knee due to component heavier than He

CR WG Summary

A.Haungs

slide19

EAS-TOP

EAS-TOP results

Also in correlation with underground TeV muon detector MACRO

CR WG Summary

A.Haungs

composition around above knee and max accelerated energy
Composition around/above knee and max accelerated energy

Composition results: knees for different components, rigidity dependent => Protons up to 1016 eV (>>max E predicted by diffusive shock acceleration) [and consequently Fe up to 1017eV]

CR WG Summary

P.Blasi

non linear particle acceleration required
Non linear particle acceleration required

Paradigm for galactic CR origin: acceleration at non-relativistic shock waves developping in supersonic motion of the ejecta of SN explosion (similar shocks in AGN/radio lobes for Xgal CRs)

Max E=balance between acceleration time and SN age. For a SN 1000 yrs old -> fractions of GeV!!!! (depends on D coefficient)

CR acceleration possible only if D coeff much smaller near the shock -> self-generation of magnetic turbulence by the accelerated particles -> max E up to 1013-1014 eV (still too low)

Non linear theories needed -> shock modifications (CR spectrum modifies spectrum of magnetic fluctuations, which in turn modifies diffusion and hence the CR spectrum. Amplification of magnetic field enhances B, that in turn enhances shock modification

CR WG Summary

P.Blasi

slide22

II knee, dip ankle: towards EeVEAS measurementsA.HaungsB.DawsonT.Gaisser et al

CR WG Summary

slide23

Questions:

Transition galactic/Xgalactic

Iron knee

Anisotropies

CR WG Summary

A.Haungs

slide24

Experimental answers

Spectrum/composition from Yakutsk, HIRES, Akeno, and in the near future from Kascade-Grande, Icetop-Icecube, Tale, Auger @1018 eV

CR WG Summary

slide25

Energy spectrum

HIRES claims the evidence of a II knee

CR WG Summary

A.Haungs

slide26

Composition

HIRES claims the evidence of a II knee

HIRES/MIA claims a change of composition @ II knee (lighter one)

CR WG Summary

A.Haungs

new detectors e g icetop icecube
New detectors, e.g. Icetop/Icecube

100 TeV - 1 EeV

CR WG Summary

new detectors e g auger at low energies
New detectors, e.g. Auger at “low” energies

Surface Array

1600 detector stations

1.5 km spacing

3000 km2

  • Auger was primarily designed for energies beyond 1019eV
  • but significant aperture at lower energies

Fluorescence Detectors

4 Telescope enclosures

6 Telescopes per

enclosure

24 Telescopes total

~2/3 tanks in field, completed in early 2007.

Routine data taking since Jan. 2004.

CR WG Summary

B.Dawson

slide30

FD-only apertures for completed Auger.Trigger aperture.

Significant aperture at lower energies

SD aperture

3 tanks with TOT = 3TOT

(fully efficient at ~ 3 EeV)4 tanks with TOT = 4TOT

(fully efficient at ~ 7 EeV)

CR WG Summary

B.Dawson

slide32

HIRES

  • Stereo observations provide the sharpest angular resolution for searching for small-scale anisotropy
    • In simulations, 68% of events above 10 EeV are reconstructed within 0.6° of their true arrival direction
  • Monocular observations currently provide the largest exposure for measuring the energy spectrum
    • HiRes-I was built first and obtained almost three-years more data than HiRes-II
  • HiRes consists of two sites
  • 12 km apart in the Utah desert (US Army Dugway Proving Ground)
  • Rings of mirrors at each site observe night sky

CR WG Summary

C.Finley

hires i and hires ii data sets
HiRes-I and HiRes-II Data Sets
  • Current analysis of HiRes-I
    • May 1997 - June 2005
  • Current analysis of HiRes-II
    • Dec. 1999 - Aug. 2004
  • HiRes-I has more exposure than HiRes-II
  • Include only pure monocular statistics for HiRes-I when doing fits

CR WG Summary

C.Finley

broken power law fits
Broken Power Law Fits
  • Fit Spectra to broken power law:
    • Allow break point to float
  • No break point:
    • Bad fit: c2=154 / 39 DOF
  • One break point:
    • Better fit: c2=67.0 / 37 DOF
    • Find Ankle at 4 EeV
  • Two break points:
    • Good fit: c2=40.0 / 35 DOF
    • Reduce c2 by 27
    • HE break at 60 EeV

CR WG Summary

C.Finley

statistical significance
Statistical Significance
  • Significance of observed events beyond break point compared with expected:
    • Expect 44.9 events
    • Observe 14
    • P(14 ; 44.9) = 7x10-8
      • 5s is 3x10-7
      • 6s is 1x10-9

CR WG Summary

C.Finley

slide36

Search for possible sources: BL Lac Correlations

  • Six results which we wish to test with independent data (all objects with m<18):
  • Note:
    • These are not independent results: the samples overlap.
    • Analysis has been a posteriori, so F values are not true probabilities.
    • Must be tested with independent data
    • Data taking through March 2006 has yielded an independent data set ~ 70% of the current sample size: Analysis is ongoing

R.U. Abbasi et al., Astrophys.J. 636 (2006) 680 [astro-ph/0507120]

Fraction of MC sets with greater ln(R) value than data

CR WG Summary

C.Finley

agasa
AGASA

0 4km

Closed in Jan 2004

S(600) as

energy estimator

111 Electron Det.

27 Muon Det.

Atmospheric depth

CR WG Summary

M.Teshima

conversion to energy and spectrum
Conversion to energy and spectrum

11 obs. / 1.3~2.6 exp.

CR WG Summary

M.Teshima

slide39

Critical review of energy estimation and sepctrum

  • Acceptance of Array
    • AGASA fast simulation (based on empirical formula and toy simulation)
    • Based on CORSIKA M.C.
    • Essentially acceptance is saturated  No difference
  • Lateral distribution of showers
    • Lateral distribution determined by experiment
    • Lateral distribution estimated by Corsika M.C.
    •  No difference
  • Attenuation of S(600)
    • Attenuation curve determined by experiment
    • Attenuation curve estimated by Corsika M.C.
    • There is systematic difference of 10-20%

CR WG Summary

M.Teshima

slide40

Preliminary spectra with recent Corsika

~10%

~15%

No difference in Models and

Compositions

Energy shift to lower direction

~10% at 1019eV

~15% at 1020eV

Above 1020eV

11events  5~6 events

Featureless spectrum

very close to E-3

CR WG Summary

M.Teshima

slide41

Arrival Direction Distribution >4x1019eV, q <50˚

  • Isotropic in the large scale  Extra-Galactic origin
  • But, Clusters in small scale (x<2.5deg)
    • 1triplet and 6 doublets (2.0 doublets are expected from random)

CR WG Summary

M.Teshima

pierre auger observatory
Pierre Auger Observatory

Hybrid EAS array under construction

in Argentina

1600 detector stations

1.5 km spacing

3000 km2

4 fluorescence eyes (6 telescopes each)

CR WG Summary

J.Cronin

conversion to energy and spectrum1
Conversion to energy and spectrum

S(1000) energy estimator

Conversion to energy through FD data

No montecarlo!

ICRC 2005

CR WG Summary

J.Cronin

slide44

Galactic center, small scale anisotropy

5 deg

20 deg

2.2 deg

Point-like source search, with different bin sizes

+: GC

Solid line: GP

Dashed line: field of view limit for Agasa

Small circle: SUGAR excess

Large circle: AGASA excess

CR WG Summary

B.Dawson

slide46

Need for models

Models relate cross sections and particle production

Models treat proton-proton, pion-proton,kaon-proton…

General caveat: calibrated at “low” energies, with fixed target data and extrapolated over many decades in E

CR WG Summary

hadronic interaction models
Hadronic interaction models

Main challenge for models: treatment of non linear interactions effects at high energies and small impact parameter

  • QGSJET I: Pomeron formalism
  • QGSJET II: + non linear effects (Pomeron-pomeron interactions)
  • Sybill 2.1: phenomenological description of “hard” screening
  • EPOS (Pomeron approach as QGSJET)
  • Black Disk Limit (BDL): semi-classical QCD
  • + other VERY phenomenological appoaches

CR WG Summary

S.Ostapchenko

important predictions for eas
Important predictions for EAS
  • p-air cross sections
  • Inelasticity
  • Cosmic ray muons:
    • Multiplicity and EAS muon content
    • Spectra and flux

CR WG Summary

S.Ostapchenko

e g p air cross section predictions
e.g., p-air cross section predictions

Results depend on calibration with spp data (10% uncertainties)

LHC data (1% accurcay) will solve the problem (Totem/CMS results)

CR WG Summary

S.Ostapchenko

cosmic ray muons multiplicity
Cosmic ray muons - multiplicity

CR experiments would like to have more muons…(EAS arrays favor iron-dominated composition, fluorescence proton-dominated)

CR WG Summary

S.Ostapchenko

crs and accelerator measurements
CRs and accelerator measurements
  • Hadronic interactions in the energy range GeV-few hundreds GeV important for understanding GeV muons production in all energy EAS (n.of pions and kaons increases with decreasing particle energy)
  • Energy range up to 400 GeV in reach of fixed target accelerators
  • They can work with light, air-like targets, and have pion and kaon beams too, very forward detection
  • HARP and MIPP experiments

CR WG Summary

mipp experiment @ fermilab
MIPP experiment @ Fermilab

Data analysis of taken data in progress

CR WG Summary

N.Solomey

conclusions
Conclusions
  • Low energy end of the spectrum:
    • Fundamental infos on CR history
    • Direct meas on Spectrum and composition towards the knee
  • I knee:
    • Light components bending
    • Rigidity dependent bending for different elements
    • Smoking gun for CR acceleration in SNR still missing, but non linear models already in place for explaining Emax
  • II knee/dip/ankle:
    • New experiments soon delivering data (KGRANDE, IceTop/IceCube, Auger…)
    • Composition mea will discriminate among scenarios for gal/Xgal transition
  • Highest end of the spectrum:
    • High statistics meas at GZK energies around the corner (Auger) [spectrum & anisotropies]
  • Interaction models: non linear regime included in most models (important @ HE). Waiting for LHC data

CR WG Summary