“the cosmic ray composition in the knee region and the hadronic interaction models” g. navarra...
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“The Cosmic Ray composition in the knee region and the hadronic interaction models” G. NavarraINFN and University, Torino, ItalyFor the EAS-TOP Collaboration
XIII International Symposium on Very High Energy Cosmic Ray InteractionsPylos Greece, 6 -12 September 2004
EAS-TOP at LNGSCampo Imperatore 2000 m a.s.l. 820 g.cm-2 data taking: 1989-2000
The Cosmic
Ray primary
spectrum
THE HIGH ENERGY GALACTIC RADIATION
KNEEDIRECT EXP.
EAS-TOP
Energy range from the direct measurements up to above the knee:Cosmic Ray primary spectrum & compositionVerification of the hadronic physics
DETECTORS:HADRONS ATMOSPHERIC C.l.ELECTROMAGNETICMUONS (E > 1 GeV)+ MUONS (E > 1.3 TeV)Deep underground GS labs.: MACRO, LVD
EAS-TOP: THE CALORIMETER& MUON TRACKER
8 x 13 cm Fe layers; 144 m2 streamer + q. proportional tubes
DETECTORS & METHODS
Hadrons p-spectrum @ E0 ~ 0.5 - 50 TeV
Cherenkov light + TeV muons p, He, CNO fluxes @ E0 ~ 100 TeV
e.m. spectrum in “knee” region E0 ~ 103 - 104 TeV
e.m. + GeV muons composition in “knee” region
e.m. + TeV muons composition in “knee” region
Verifications of methods and HE physics used
e.m. anisotropies & search for gamma primaries
CORSIKA-QGSJET
Size and energy spectra:
Ne Eo
Astrop. Phys. 10 (1999) 1
Ne-N distributions
3-component fit: L, CNO, H in LogNe = 0.2 intervals of Ne
2 = i (fci – fexp
i)2/i2 fci = wLfsL
i + wCNOfsCNOi + wHfsH
i
Simulations with = 2.75 spectraL = “p” or “50%p + 50% He” ; CNO = N; H = Fe
Frac
tion
of
even
ts
Frac
tion
of
even
ts
The composition in the ‘knee’ region
Mass group Heavier primary spectra harder Ek Z ?
l > 3.1
CNO ~ 2.75
Fe = 2.3 – 2.7
TeV muon multiplicity fits in MACRO (TeV )
L = p + He
H = Mg + Fe
L+H
Measured
EAS-TOP & MACRO (TeV )
L = p + He H = Mg + Fe
Astrop. Phys., 20 (2004) 641
< ln A > vs. E0
particle and energy flux in p-p
MACRO EAS-TOP
E. M.
The hadronic interaction models (CORSIKA)
Primary protons:
N Ne
= 0.820 ± 0.007
= 0.792 ± 0.007
= 0.789 ± 0.008
= 0.77 ± 0.02
Evolution of composition< Ne-N
EXP= 0.907 ± 0.004
EXTRCMP= 0.79 ± 0.02
MAX-VENUS= 0.820 ± 0.007
QGSJET: agreement with extrapolated direct measurements!
NO INTERACTION MODEL CAN ACCOUNT FOR THE INCREASING N vs. Ne WITHOUT INCREASING PRIMARY MASS
Component dominating at the “knee”?
He – p spectra similar RUNJOB
He spectrum harder JACEE
From “direct” measurements:JACEE
RUNJOB
JACEERUNJOBEAS-TOP
THE EAS-TOP CHERENKOV DETECTOR
2 wide angle detectors per telescope(MIRROR: A = 0.5 m2 , f.l. = 40 cm , f.o.v. = 0.16 sr)
equipped with 7 photomultipliers (d = 6.8 cm , f.o.v. = 0.023 sr)
Trigger threshold: Nphe,th = 120 phe / mirror (Ethr 40 TeV at r = 130 m) Trigger rate: 7 Hz/telescopeCherenkov event: coincidence in T = 30 ns , between any 2 corresponding PMs.
5
MACRO UndergroundGran Sasso Labs.depth: 3100 m w.e. Eth ~ 1.3 TeV 76.6 x 12 x 4.8 m
< 1o
20 m at surface level
Astrop. Phys., 21 (2004) 223
Proc. 28th ICRC, 1 (2003) 115
A different approach: EAS-TOP & MACRO
EAS-TOP (Cherenkov detector):
total energy through the amplitude
of the detected Cherenkov light signal.
MACRO (muondetector):
EAS primaries with En > 1.3 TeV/n
EAS geometry through the track
( r ~ 20 m, ~ 10 uncertainties)
MACRO and EAS-TOP are separated by 1100-1300 m of rock: E 1.3 - 1.6 TeV
DATA SET
t = 7s
September 1998 – May 2000
Tot. Time T = 208 h
5 telescopes
exposure 830 day m2 sr
angular window:
: 16 < < 58 , 127 < <
210
MACRO events in T and :
35814
with EAS-TOP in t = 7s:
3830
(expected accidental events < 3.0)
Event coincidence is established
off-line (GPS system - T < 1s)
Coincidence Peak
tMACRO–t Cherenkov (s)
t = 7s
7
E ≈ 80 TeV Np ≈ N
He
E ≈ 250 Tev Np ≈ N
He ≈ NCNO
C.l. yield: p ~ He ~ CNO
p
He
CNO
Fe
C.l. + TeV muon analysis
Mg
p, He, CNO @ ~ 100-200 TeVInformation EAS-TOP
& MACROJACEE RUNJOB
Jp+He
(80 TeV)
18 ± 4 12 ± 3 8 ± 2
Jp+He+CNO
(250 TeV)
1.1 ± 0.3 0.7 ± 0.2 0.5 ± 0.1
Jp/ Jp+He
(80 TeV)
0.29 ± 0.09 0.45 ± 0.12 0.63 ± 0.20
Jp+He/ Jp+He+CNO
(250 TeV)
0.78 ± 0.17 0.70 ± 0.20 0.76 ± 0.25
JHe
(80 TeV)
12.7 ± 4.4 6.4 ± 1.4 3.1 ± 0.7
x 10-7 m-2s-1sr-1TeV-1
EAS-TOP & MACRO data
EAS-TOP & MACRO data + p-flux
p+He p+He+CNO
The Cherenkov light LDF
WITH JACEE FLUX
Test of energy release in the atmosphere of QGSJET:
R = (42 m) / (134 m)
= Ne (370 g/cm2) / Ne (505 g/cm2)
(Rexp – Rth)/Rth = 0.14 ± 0.09
Ne and N spectra
Ne N
Sec Ik*107 Nk chi**2/df m-2s-1sr-1
1.00-1.05 2.56 2.96 0.06 1.1 0.1 6.08 0.03 7.8/111.05-1.10 2.56 2.86 0.05 1.3 0.2 5.95 0.04 8.4/111.10-1.15 2.56 2.84 0.04 1.0 0.1 5.95 0.04 5.3/111.15-1.20 2.56 2.82 0.08 0.8 0.2 5.92 0.06 7.6/111.20-1.25 2.56 2.92 0.09 0.5 0.1 5.94 0.05 4.6/111.25-1.30 2.56 2.75 0.07 1.4 0.4 5.62 0.07 2.8/11
chi**2/df (1slope)1.00-1.05 3.21 0.06 3.42 0.10 1.2 0.3 4.65 0.10 10.4/10 18.7/121.05-1.10 3.18 0.08 3.45 0.10 1.4 0.2 4.65 0.10 9.3/10 20.7/121.10-1.15 3.18 0.09 3.40 0.20 0.6 0.2 4.75 0.15 6.9/10 9.9/121.15-1.20 3.12 0.15 3.4 0.10 1.6 0.5 4.55 0.15 5.9/10 14/12
Agreement inside errors (~ 30%)
2 slopes
Decreasing with increasing zenith angle
Ne
N
N Ne
= (e –1) /(-1) = 0.7 – 0.8
In agreement with models SAME BENDING COMPONENT ?
IFSAME BENDING COMPONENTin Ne and N spectra
We can identify it.
We construct for each component (p, He, CNO, Mg, Fe) the energy spectrum fitting the size spectrum in the region of the knee.
From such energy spectra we construct for each component the corresponding N spectrum, to be compared with the measured one.
The result of such comparison
Muon size spectrum: measured and expected for different primaries
on the base of the Ne spectrum
If “Knee” on Helium primaries
Ek (He) = (3.5 0.3) 1015 eV
VENUS
QGSJET
NEXUS
The primary spectrum from EAS-TOP
Natural evolution…..
KASCADE-Grande
KASCADE-Grande
If : E k,Z = Z * E k,1
SEARCH FOR IRON “KNEE” AT ~ 1017 eV
PRIMARY COMPOSITION: 1016 - 1018 eV
STUDY OF C.R. INTERACTIONS AT UHE
N (> 1018 eV) ~ 250 (3 y data taking)
At the threshold of Auger (High Resolution)
P,He
iron
Eknee = 3 – 4 PeV
EAS-TOP/KASCADE
Hadron spectrum at 820 g/cm2 & comparison with sea level (1033 g/cm2)
Calculated QGSJET
Exp. KASCADE/EAS-TOP
E0 = 0.5 – 50 TeVProton spectrum at TOP
Astrop. Phys. 19 (2003) 329 He contribution subtracted
S(Eo) = (9.8 1.1stat 1.6sys) 10–5 (Eo/1000) –2.80 0.06 m-2 s-1 sr-1 GeV-1