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

Report on UHE cosmic rays WGReport on UHE cosmic rays WG

Piera L. GhiaIFSI-INAF, Torino, and LNGS-INFN, Assergi, Italy

Tom GaisserUniversity of Delaware, USA

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TeV Particle Astrophysics IIUniversity of Wisconsin, Madison

Piera L. Ghia CR WG Summary TeV II, Madison 2006

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What we had in mind:

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

Theoretical point of Theoretical point of viewview

CR interactions in the CR interactions in the atmosphereatmosphere

Direct measDirect meas(balloons/satellites)(balloons/satellites)

EAS measEAS measInteraction in airInteraction in air




Theoretical point of viewTheoretical point of view

Came “for free” in the Came “for free” in the plenary session (P. Blasi, plenary session (P. Blasi,

Open problems on the Open problems on the origin of cosmic rays) & origin of cosmic rays) & S.Yoshida (EHE signals)S.Yoshida (EHE signals)

WG: Acceleration at WG: Acceleration at astrophysical shocksastrophysical shocks

P.BlasiP.Blasi

CR interactionsCR interactions

S.OstapchenkoS.OstapchenkoN. Solomey (MIPP)N. Solomey (MIPP)

++G. Catanesi G. Catanesi

(Hadroproduction @ (Hadroproduction @ CERN, plenary)CERN, plenary)




Experimental status of the artExperimental status of the art

Direct measurementsDirect measurementsS.SwordyS.Swordy

From PeV to EeVFrom PeV to EeVA.HaungsA.Haungs

Around and Above EeVAround and Above EeVB.DawsonB.DawsonC.FinleyC.Finley

M.TeshimaM.TeshimaJ. Cronin (PS)J. Cronin (PS)

Bai, Gaisser et al (poster)Bai, Gaisser et al (poster)

Direct Cherenkov @ kneeDirect Cherenkov @ kneeS.WakeleyS.Wakeley




Lower end of the spectrumLower end of the spectrumDirect measurementsDirect measurements

S.SwordyS.Swordy

Below the kneeBelow the knee




CR historyCR 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

S.Swordy


CR lifetime from meas of secondary radionuclides:



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

=15±1.6 Myr=15±1.6 Myr

S.Swordy


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?)

S.Swordy




Towards the kneeTowards the kneeDirect measurementsDirect measurements

S.SwordyS.Swordy

Below the kneeBelow the knee




Magnetic spectrometers (AMS, BESS, CAPRICE…)

Same magnetic

rigidity spectra (parallel with

E), power law

Thin calorimeters (JACEE, RUNJOB, ATIC)

Differences here: He intensity larger for Jacee than Runjob

H and He spectra

S.Swordy


Heavier elements and compositionHeavier elements and composition



Up to 1000 TeV/nUp to 1000 TeV/nRunjobRunjob: constant: constant(but Jacee(but Jacee: mass increase : mass increase towards the knee)towards the knee)



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

S.Swordy




To go further towards To go further towards the knee:the knee:

Ultra long duration Ultra long duration balloon flightsballoon flights

CREAMCREAM





OxigenOxigen

CarbonCarbon

S.Swordy




I kneeI kneeEAS measurementsEAS measurements

A.HaungsA.Haungs


I kneeI knee



Questions:Questions:Knee positionKnee positionComposition @ Composition @ kneekneeCR anisotropyCR anisotropySpectrum structureSpectrum structure

A.Haungs


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

Experimental answersExperimental answers










Unfolding performed for

Different interactions models (Sybill, QGSJET)

Different low energy interaction models (Gheisha, Fluka)

Analysis depends Analysis depends crucially on crucially on interaction modelsinteraction models

KascadeKascade

A.Haungs




Knee @ 5PeVKnee @ 5PeV



KascadeKascade

A.Haungs




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

Tibet resultsTibet results

TibetTibet

A.Haungs




EAS-TOP resultsEAS-TOP results

Also in correlation with underground TeV muon Also in correlation with underground TeV muon detector MACROdetector MACRO

EAS-TOPEAS-TOP

A.Haungs


Composition around/above knee Composition around/above knee and max accelerated energyand 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]

P.Blasi


Non linear particle acceleration requiredNon 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

P.Blasi




II knee, dip ankle: towards EeVII knee, dip ankle: towards EeVEAS measurementsEAS measurements

A.HaungsA.HaungsB.DawsonB.Dawson

T.Gaisser et alT.Gaisser et al




Questions:Questions:Transition Transition galactic/Xgalacticgalactic/XgalacticIron kneeIron kneeAnisotropiesAnisotropies

A.Haungs




Experimental answersExperimental answers





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


HIRES claims the evidence of a II knee

Energy spectrumEnergy spectrum



A.Haungs


HIRES claims the evidence of a II knee

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

CompositionComposition



A.Haungs


New detectors, e.g. Kascade-GrandeNew detectors, e.g. Kascade-Grande



A.Haungs


New detectors, e.g. Icetop/IcecubeNew detectors, e.g. Icetop/Icecube



100 TeV - 1 EeV100 TeV - 1 EeV


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

Surface Array 1600 detector stations 1.5 km spacing 3000 km2

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.

• Auger was primarily designed for energies beyond 1019eV

• but significant aperture at lower energies

B.Dawson


FD-only apertures for completed Auger.

Trigger aperture.

Significant aperture Significant aperture at lower energiesat lower energies

SD aperture

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

4 tanks with TOT = 4TOT(fully efficient at ~ 7 EeV)

B.Dawson




EeV and aboveEeV and aboveEAS measurementsEAS measurements

C. FinleyC. FinleyM.TeshimaM.Teshima

J.CroninJ.Cronin


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

HIRESHIRES

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

C.Finley


HiRes-I and HiRes-II Data SetsHiRes-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

C.Finley


Broken Power Law FitsBroken Power Law Fits Fit Spectra to broken power

law: Allow break point to float

No break point: Bad fit: 2=154 / 39 DOF

One break point: Better fit: 2=67.0 / 37 DOF Find Ankle at 4 EeV

Two break points: Good fit: 2=40.0 / 35 DOF Reduce 2 by 27 HE break at 60 EeV

C.Finley


Statistical SignificanceStatistical Significance

Significance of observed events beyond break point compared with expected: Expect 44.9 events Observe 14 P(14 ; 44.9) = 7x10-8

5 is 3x10-7

6 is 1x10-9

C.Finley


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]

Search for possible sources: BL Lac CorrelationsSearch for possible sources: BL Lac Correlations

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

C.Finley


AGASAAGASA

0 4km

111 Electron Det.27 Muon Det.

Closed in Jan 2004

Atmospheric depth

S(600) as energy estimator

M.Teshima


Conversion to energy and spectrum Conversion to energy and spectrum

11 obs. / 1.3~2.6 exp.

M.Teshima


Critical review of energy estimation and sepctrumCritical 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 of S(600) Attenuation curve determined by experimentAttenuation curve determined by experiment Attenuation curve estimated by Corsika M.C.Attenuation curve estimated by Corsika M.C. There is systematic difference of 10-20%There is systematic difference of 10-20%

M.Teshima


Preliminary spectra with recent CorsikaPreliminary spectra with recent Corsika

No difference in Models and Compositions

Energy shift to lower direction~10% at 1019eV~15% at 1020eV

Above 1020eV11events 5~6 events

Featureless spectrumvery close to E-3

~10%

~15%

M.Teshima


Arrival Direction Distribution >4x1019eV, <50˚

Isotropic in the large scale Extra-Galactic origin But, Clusters in small scale (<2.5deg)

1triplet and 6 doublets (2.0 doublets are expected from random)

M.Teshima


Pierre Auger ObservatoryPierre Auger Observatory

Hybrid EAS array under construction in Argentina 1600 detector stations 1.5 km spacing 3000 km2

4 fluorescence eyes (6 telescopes each)

J.Cronin


Conversion to energy and spectrum Conversion to energy and spectrum

S(1000) energy estimatorS(1000) energy estimatorConversion to energy Conversion to energy through FD datathrough FD dataNo montecarlo!No montecarlo!

ICRC 2005ICRC 2005

J.Cronin


Galactic center, small scale anisotropyGalactic center, small scale anisotropy

+: GC+: GCSolid line: GPSolid line: GPDashed line: field of view Dashed line: field of view limit for Agasalimit for AgasaSmall circle: SUGAR Small circle: SUGAR excessexcessLarge circle: AGASA Large circle: AGASA excessexcess

Point-like source Point-like source search, with different search, with different bin sizes bin sizes

2.2 deg2.2 deg

5 deg5 deg

20 deg20 deg

B.Dawson

Piera L. Ghia CR WG Summary TeV II, Madison 2006J.Cronin




Need for modelsNeed for modelsModels relate cross sections and particle productionModels relate cross sections and particle productionModels treat proton-proton, pion-proton,kaon-Models treat proton-proton, pion-proton,kaon-proton…proton…

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


Hadronic interaction modelsHadronic interaction models

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

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

small impact parametersmall impact parameter

S.Ostapchenko


Important predictions for EASImportant predictions for EAS

p-air cross sections Inelasticity Cosmic ray muons:

Multiplicity and EAS muon contentSpectra and flux

S.Ostapchenko


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



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

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

S.Ostapchenko


Cosmic ray muons - multiplicityCosmic ray muons - multiplicity



CR experiments would like to have more CR experiments would like to have more muons…(EAS arrays favor iron-dominated muons…(EAS arrays favor iron-dominated

composition, fluorescence proton-dominated)composition, fluorescence proton-dominated)S.Ostapchenko


CRs and accelerator measurementsCRs 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


MIPP experiment @ FermilabMIPP experiment @ Fermilab



Data analysis of taken data in progressData analysis of taken data in progressN.Solomey


ConclusionsConclusions

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

Documents

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