Cosmic Ray Physics with the IceTop Air Shower Array. Hermann Kolanoski Humboldt-Universität zu Berlin

Transcription

1 Cosmic Ray Physics with the IceTop Air Shower Array Hermann Kolanoski Humboldt-Universität zu Berlin SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array

2 Outline Cosmic rays: what IceCube/IceTop can contribute IceTop: the air shower array of IceCube Energy spectra Methods of composition determination IceTop-InIce coincidences composition... and more: heliospheric, atmospheric physics with IceTop SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 2

3 Energy Spectrum at the Knee IceTop Rigidity : R p z e B O Fe H 10 kpc SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 3

4 CR Composition from Direct Measurements SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 4

5 ...and from Indirect Measurements KASCADE results KASCADE Coll., Astrop.Phys. 24 (2005) 1; Astrop.Phys. 31 (2009) 86 relative abundances depend very much on high-energy hadronic models SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 5

6 IceTop Surface Array of IceCube IceTop air shower detector 80 stations on 1 km 2 IceCube Neutrino/Muon detector 4800 optical modules in 1 km 3 ice depth: m 1000 m specialty for cosmic ray physics: combination of both detectors air shower + penetrating muons in depth SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 6

7 The IceCube Collaboration Canada: University of Alberta USA: Bartol Research Institute, Delaware Pennsylvania State University UC Berkeley UC Irvine Clark-Atlanta University University of Maryland University of Wisconsin-Madison University of Wisconsin-River Falls Lawrence Berkeley National Lab. University of Kansas Southern University and A&M College, Baton Rouge University of Alaska, Anchorage Ohio State University University of Alabama Georgia Institute of Technology Sweden: Uppsala Universitet Stockholm Universitet UK: Oxford University Switzerland: EPFL Germany: Universität Mainz DESY-Zeuthen Universität Dortmund Universität Wuppertal Humboldt Universität MPI Heidelberg RWTH Aachen Universität Bonn Universität Bochum Belgium: Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut Japan: Chiba University University of West Indies ~36 institutions, ~250 members New Zealand: University of Canterbury SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 7

8 IceTop Detector Array 2009/10 after 2009/10 season 73 stations (146 tanks) SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 8

9 IceTop Signal Recording voltage leading edge charge [PE] baseline DOMs time [ns] conversion to Vertical Equivalent Muons 1 VEM 150 PE signal distribution in untriggered calibration runs SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 9

10 Longitudinal Shower Profile Gaisser-Hillas Formula: SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 10

11 Shower Development for Different Nuclei N e/m first interaction μ surface observation proton X / g cm -1 N earlier earlier, same height e/m more heavier nucleus: μ earlier maximum more muons X / g cm -1 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 11

12 Air Shower Reconstruction tank signals = ( x, q, t i i i ) shower direction: θ, φ shower centre x c, y c primary energy: E 0 (with mass hyp.) shower age: s y c θ x c SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 12

13 Response Matrix Φ true S R S rec true reconstructed E protons iron Response R includes: smearing, acceptance, mis-reconstruction more diagonal for protons because energy is determined with proton hypothesis SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 13

14 Unfolding with a) proton or b) iron - Preliminary Results! - knee Flux not isotropic for proton or iron only assumptions Mixed composition needed! Isotropy requirement leads to Composition sensitivity with IceTop only! SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 14

15 Shower Development for Different Nuclei N e/m observation proton first interaction μ heavier nucleus N earlier earlier μ e/m X / g cm -2 more South Pole atmospheric depth 680 g/cm 2 close to shower maximum for ~ 1 PeV X / g cm -2 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 15

16 Unfolding with Composition Models preliminary fits in angular bins: proton only iron only 2-component model poly-gonato model SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 16

17 Generating the Response Matrix for Different Models SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 17

18 Preliminary Results with Poly-Gonato Model 1 month of data only 26/80 of the detector 1 to 80 PeV S.Klepser et al., ICRC 2007 E knee = (3.1 ± 0.3 (stat.) ± 0.3 (sys.)) PeV γ 1 = 2.71 ± 0.07 (stat.) (prelim) γ 2 = ± (stat.) ± 0.08 (sys.) Systematics: 9 11 % in E first IceTop analysis for energy spectrum we know now our main systematics SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 18

19 Comparison with other Experiments S.Klepser, Dissertation Humboldt Univ. Berlin June 2008 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 19

20 IceTop Prospects for Composition Analyses IceTop InIce coincidences N IceTop: zenith angle dependence of shower development N Muon counting with IceTop Complementary methods test of models N X / g cm -2 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 20

21 IceTop InIce Coincidences shower size E 0 InIce e/ A IceTop SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 21

22 An IceCube IceTop Coincident Event Tom Feusels, Gent HE muons in IceCube come from first interactions complementary sensitivity to muon counting at the surface SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 22

23 Composition-dependence: factor 2-3 between p and Fe T. Feusels, J. Eisch, C. Xu (IceCube, ICRC 2009, paper 0518) SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 23

24 Muon Fraction in IceTop Proton Iron / 1 PeV, vertical / CORSIKA (Sybill + Fluka) electromagnetic component dominates electrons/gammas iron proton no big difference between QGSJET II and SYBILL muons SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 24

25 Muons at the Surface Adam Lucke, 2008 Muon abundance sensitive on mass - in addition: Soft Local Coincidence measure single muons - alternative (?): analysis of rise time of signal pulses SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 25

26 Atmospheric Variations as observed by IceCube SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 26

27 Ozon Layer Temperature Ozone concentration over the southern hemisphere Sept. 20th 2002 Sept. 25th 2002 The Antarctic ozone layer is at pressure levels of hpa where also the first cosmic ray interactions occur. IceCube closely probes the temporal behavior of the stratospheric temperatures and the ozone hole dynamics SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 27

28 Heliospheric Physics 13 Dec 2006 Solar Flare Detection by IceTop [ApJ Lett., 689: L65 L68, 2008] On 2006 December 13 the IceTop air shower array at the South Pole detected a major solar particle event.... the response of the IceTop tanks with multiple thresholds deployed at high altitude with no geomagnetic cutoff, rate increase at 2 different thresholds SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 28

29 Heliospheric Physics with IceTop By numerically simulating the response of the IceTop tanks, we determined the particle energy spectrum in the energy range GeV. This is the first such spectral measurement using a single instrument with a welldefined viewing direction. comparison with neutron detectors plans for improved resolution of solar particle spectra: take differential energy spectra ( multi-threshold rates) SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 29

30 Summary first preliminary IceTop energy spectrum for 26/80 of the detector, 1 month the spectrum was analysed in terms of composition models exploiting the zenith angle dependence of shower development on the composition prospects for composition analysis up to 1 EeV: - IceTop-InIce coincidence yielding: energy muon number correlations - muon counting in IceTop - complementary methods test of models other science topics open up: - atmosphere, sun,... SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 30

31 The End SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 31

32 Backups SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 32

33 ... for Example Snow: SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 33

34 Snow Effect µ/em vs snow depth muon calibration: reconstructed core positions: data MC without snow MC with snow SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 34

35 CR Composition from Air Shower Measurements KASCADE [W.D. Apel et al. / Astroparticle Physics 31 (2009) 86 91] Systematic uncertainties from interaction models (LE: GEISHA/FLUKA; HE: QGSJET/SYBILL/EPOS..) Conclusion: composition in the region of indirect measurements needs more work SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 35

36 Filling tanks, December 2008 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 36

37 Air Shower Parameters SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 37

38 Lateral Distribution Function 3 examples Average detector response S(E) can be used to weight particles in CORSIKA shower simulations IceTop Tank Signal LDF κ = = const. DLP-Function: ("Double Logarithmic Parabola ) for 1 PeV, 30 : S VEM shower size S( R) S R 0 R R 0 log 10 R R 0 arxiv: S Ro E 0 assignment with proton hypothesis composition as correction in response matrix SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 38

39 Systematics 9 11 % in E SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 39

40 Comparison with other Experiments relatively low flux or energy IceTop preliminary but systematic uncertainties in all experiments: typ. flux uncert % ( E 7-8%) E 20% S.Klepser, Dissertation Humboldt Univ. Berlin June 2008 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 40

41 Two events in IceCube Color time code: red is early, blue is late 800 PeV cosmic-ray > 1000 in deep IceCube -induced in IceCube-59 SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 41

42 Muon Signature electromagnetic muons and el.mag. showers not a priori distinguishable # Photonen Muons muons stick out when expectation value for e.m. low: signal em signal muon # Photonen SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 43

43 e.m. / muon Ratio from Pulse Height Spectrum measured expected Enhancement of hits with 1 VEM charge in outer region if signal em signal muon SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 44

44 FromtheKneeto theankle SNOWPAC - March 22-28, 2010 Hermann Kolanoski: IceTop Air Shower Array 45