Follow-up on Cosmic Ray Composition

(1)

Follow-up on Cosmic Ray Composition

Genoveva Micheva

October 1 2007

KTH 5A5461

Experimental Techniques in Particle Astrophysics

(2)

Outline

(3)

Energy Spectrum

Direct detection 10

⁷

-10

¹⁰

eV- Solar 10

¹⁰

-10

¹⁵

eV - Galactic Indirect detection

10

¹⁵

-10

²¹

eV - Extragalactic?

Simple power law:

N(E)dE = K · E

^α

dE,

α : −2.7 → −3.1 at “knee” E

_max

reached in SNe accelaration ⇒

acceleration mechanism changes?

(4)

Direct detection

E . 1PeV

ACE

[Advanced Composition Explorer]

NINA

[New Instrument for Nuclear Analysis]

IMP

(Interplanetary Monitoring Platform)

PAMELA

[Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics]

CREAM

[Cosmic Ray Energetics and Mass Balloon Experiment]

JACEE

[Japanese-American Collaborative Emulsion Experiment]

RUNJOB

[RUssian-Nippon JOint Balloon Experiment]

(5)

Indirect detection

E & 1PeV

Extensive air shower detectors:

KASCADE

[KArlsruhe Shower Core and Array DEtector]

AGASA

[Akeno Giant Air Shower Array]

SPASE 2

[South Pole Air Shower Array]

Energy Threshold

High(> 50 · 10

¹²

eV)

Background Rejection

Moderate(> 50%)

Field of View

Large(> 45 deg)

Duty Cycle

High (> 90%)

Cerenkov detectors:

MAGIC

[Major Atmospheric Gamma Imaging Cerenkov telescope]

CANGAROO

[Collaboration between Australia and

Energy Threshold

Low(< 200 GeV)

Background Rejection

Excellent(> 99.7%)

Field of View

Small(∼ 2 deg)

Low(5-10%)

(6)

KArlsruhe Shower Core and Array DEtector - KASCADE

1

Scintillation detector array 252 detector stations, 13m apart

rectangular grid, 200m×200m liquid scintillation counters (e/γ detection)

plastic scintillators (µ detectors)

2

Central Detector

hadron Fe sampling calorimeter liquid ionization chambers

3

Muon Tracking Detector

(7)

Extended Air Showers (EAS)

Photon or hadron-induced 3 components

Hadronic Muonic

Electromagnetic

KASCADE - all 3 components EAS measurements indicate mean atomic weight of the primaries (e.g.

“CNO group”, “Fe group”, etc.)

(8)

KArlsruhe Shower Core and Array DEtector - KASCADE

Shower observables

number of EAS hadrons above energy treshold 100 GeV, N

E >100GeV

h

energy of most energetic hadron in shower, E

_h^max

energy sum of reconstructed hadrons, P E

_h

Calibration difficult - no collider data available

µ energy deposition taken as standard

⇒ mean atomic mass of primary

particle

(9)

KASCADE/RUNJOB

Energy spectrum for each component

All particle energy spectrum

(10)

Cutoff Rigidities

Smart, D. F.; Shea, M. A.; Humble, J. E., “Characteristics of cosmic ray cutoffs for a satellite orbiting at 400 KM - The effect of the solid earth”, (COSPAR, IUPAP, IAU, IAGA, and SCOSTEP, Symposium on Cosmic Rays in the Heliosphere, Budapest, Hungary, June 2-14, 1980.) Advances in Space Research, vol. 1, no. 3, 1981, p. 165-168.

Yanagimachi, T.; Hisano, K.; Doke, T.; Hamasaki, R.;

Hayashi, T., “Observations of ultraheavy cosmic ray particles with Z greater than 45 at 10 GV geomagnetic cutoff rigidity”, Physical Society of Japan, Journal (ISSN 0031-9015), vol. 55, June 1986, p. 2070-2085, June 1986.

Humble, J. E.; Smart, D. F.; Shea, M. A., “Cosmic ray cutoffs at 400 KM applicable to the HEAO-C satellite”, International Cosmic Ray Conference, 16th, Kyoto, Japan, August 6-18, 1979, Conference Papers. Volume 4.

Follow-up on Cosmic Ray Composition