TAUP Conference, Sendai 11-15 September 2007

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The primary spectrum in the transition region between

direct and indirect measurements (10 TeV – 10 PeV)

M. Bertainaa,*, G. Battistonib, S. Murarob, G. Navarraa, A. Stamerrac

a) Universita’ di Torino and INFN Torino, Italyb) Universita’ di Milano and INFN Milano, Italy

c) Universita’ di Siena and INFN Pisa, Italy

* At present JSPS fellow at RIKEN, Japan

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The basic question:

Based on the experimental data collected so farfrom ‘direct’ and indirect experiments, is it possibleto extract the primary spectrum of the different components?

The main request:

The proposed solution should be compatible with themajority of the experimental data, if possible, obtained usingdifferent techniques and observables, sensitive to different primary particles and characteristics of their cascades in air.

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The ‘all particle’ spectrum

10TeV 10PeV

Overlapping region

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Techniques

‘Direct’ measurements (balloons):Emulsion Chambers (JACEE & RUNJOB) 10 TeV - ~500 TeVCalorimeters (ATIC & CREAM) 50 GeV – 200 TeVGood charge resolution but low statistics Sensitive to the first interaction of the primary particle

Indirect measurements (EAS arrays):Electromagnetic component (scintillators) > 100 TeVMuons (tracking detectors, scintillators) > MeV/GeV (surface), TeV (underground)Hadrons (calorimeters) > 500 GeVCherenkov light (telescopes) > 15 TeVHigh statistics Energy and composition extracted from comparison with simulations

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RUNJOB Emulsion chamber on

balloon

diffuser (～4cm)

target (～10cm)

thin EC(～5c.u.)

spacer (～20cm)

A = 0.4 m2; obs time: 1437.5 h, exposure 575 m2h

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Atic-2 20 days Antarctica flight Exp. about 0.3 of RUNJOBBGO calorimeter: 1.15 int

New calorimetersATIC

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Measurement Techniques of Air Showers

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Nucl. Instr. Meth.Nucl. Instr. Meth.A513 (2003) 490A513 (2003) 490

PRIMARY PROTONPROTON FLUX FROM HADRON FLUX DATAKASCADE CALORIMETER500 GeV – 1 PeV

KASCADE

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He & CNO (80 – 250 TeV)from Cherenkov light & HE muons:

EAS-TOP & MACROTHE 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.

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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 Proc. 29th ICRC, HE11 (2005) 101

Total exposure 20,000 h m2 sr x 15 of direct exp.

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MACRO and EAS-TOP are separated by 1100 - 1300 m of rock corresponding to a threshold E 1.3 - 1.6 TeV.

MACRO (as a detector): - EAS from primaries with En > 1.3 TeV/n - EAS geometry through the track

(~20 m uncertainty) .

EAS-TOP (Cherenkov detector): total energy through the amplitude

of the detected Cherenkov light signal.

Energy uncertainties:28% stat.+ syst

He + CNOHe + CNO

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KEY POINT OF THE ANALYSIS

Beams are well defined:• p at Eo < 50 TeV• p+He at 50 < Eo < 100 TeV• p+He+CNO at Eo > 100 TeV

• E ≈ 80 TeV Np ≈ N

He

• E ≈ 250 Tev Np ≈ N

He ≈ NCNO

Same efficiency (inside 15%) inTeV production. Relative abundances are not distortedPrimary Energy (TeV)

80 TeV

250 TeV

Our simulation agrees with Forti et al., Phys rev. D 42, 3668 (1990) using: E,th = 1.6 TeV and = 35o

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Cherenkov light: H.E.S.S.Iron: 15 – 150 TeV

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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

EAS-TOP

KASCADE

Ne – N(GeV)E = 1 - 30 PeV

Ne – N(TeV)E = 1 - 30 PeV

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KASCADE: energy spectra of single mass groups

un

fold

in

g

Searched: E and A of the Cosmic Ray ParticlesGiven:Ne and N for each single event

solve the inverse problem

with y=(Ne,Ntr) and x=(E,A)

Measurement:KASCADE array data900 days; 0-18o zenith angle0-91m core distancelg Ne > 4.8;lg N

tr > 3.6 685868 events

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HEMAS:0 = (5.0±0.1) cm-2s-1sr-1GeVp-1A , p = 2.79±0.04

SIBYLL:0 = (4.1±0.1) cm-2s-1sr-1GeVp-1A , p = 2.77±0.05

MACRO (E>1.3 TeV)

The most exploited technique in the past (MUTRON, Alkoffer, etc…)

The muon spectrum --> All nucleon spectrum

MACRO Coll., Phys. Rev. D, Vol. 52 p.3793 (1995)

AMANDA (E>300 GeV)

AMANDA Coll., 28th ICRC, HE 2.1 p.1211 (2003)

0,H = (0.106±0.007) m-2s-1sr-1TeV-1, H = 2.70±0.02

16G. Battistoni et al 29th ICRC 6, 309 (2005)

The new FLUKA Code

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L3 and Fluka: agree < 10%

S. Muraro, Ph.D. Thesis, 2006 Univ. Milano

FLUKA sim. L3 data

Vertical flux

L3+Cosmics

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L3 and Fluka: agree < 10%

FLUKA sim. L3 data

Inclined flux (=53-58)

S. Muraro, Ph.D. Thesis, 2006 Univ. Milano

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Primary SpectrumPrimary SpectrumExample: proton

and helium component

AMS-BESS fit 2001Modified NASA spectrum [G.D.Badhwar and P.M.O'Neill, Adv. Space

Res. Vol.17, No. 2 (1996) 7.] (proton and helium only) to take into account AMS 1998 and BESS data.

Include Solar Modulation model Date dependentS. Muraro

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Atmospheric muons at Atmospheric muons at mountain altitudemountain altitude

Atmospheric muons at Atmospheric muons at mountain altitudemountain altitude

We compared FLUKA simulations with the experimental data of atmospheric muons taken at the top of Mt. Norikura, Japan, with the BESS detector.

2770 m above sea level (11.2 GV).

The energy range for muons extends up to 100 GeV.

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BESS 99 @ Mt. BESS 99 @ Mt. NorikuraNorikura

Phys. Lett. B 564 (2003), 8 – 20

BESS 99 @ Mt. BESS 99 @ Mt. NorikuraNorikura

Phys. Lett. B 564 (2003), 8 – 20

cone of ~11o

-GeomagneticCut-off: 11.2 GV

+

2,700 m asl

Looks better at higher energies

S. Muraro

FLUKA sim. BESS data

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All particle spectrum

~2.6

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The Proton Spectrum

Nice agreement among all techniques

p~2.7

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The Helium Spectrum

Some discrepancies, but high He flux is preferred

He~2.55

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The CNO spectrum

At PeV energies the spectrum is divided only in 3-5 mass groups, therefore, fluxes might be slightly overestimated.Direct measurements report often C+O

CNO~2.55

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The Iron Spectrum

CAUTION: the definition of Fe group depends on the experiment

Fe~2.55

Fe~2.65

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A plausible answer from the data….

=2.65