Cosmicray physics with Ice Cube 125 m Ice
Cosmic-ray physics with Ice. Cube 125 m Ice. Top is the surface component of Ice. Cube as a three-dimensional South Pole Astro cosmic-ray air Tom Gaisser shower detector April 4, 2011 1
Cosmic ray showers from above Two different kinds of events Closely related scientifically: • Neutrinos from cosmic ray sources • Cosmic rays after propagation Ice. Top South Pole 2835 m. a. s. l. 1450 m Ice. Cube Neutrinos from all directions 2450 m Primarily nm-induced m from below South Pole Astro April 4, 2011 Tom Gaisser 2
Ee. V event in Ice. Cube-40 Ratio: Deep muons / Surface size Sensitive to primary composition South Pole Astro April 4, 2011 Tom Gaisser 3
Cosmic-ray physics with Ice. Cube • Ice. Cube sees cosmic ray events from all directions – – 30, 000 atmospheric n/year 100 billion atmospheric m/year 1 billion air showers/yr in Ice. Top ~10% in coincidence with deep Ice. Cube • Spectrum/composition: – Te. V to Ee. V South Pole Astro April 4, 2011 Tom Gaisser 4
Huge m statistics allows study of anisotropy @ < 1 per mil South Pole Astro April 4, 2011 Tom Gaisser 5
From presentation of R. Abbasi, SNOPAC 2011 South Pole Astro April 4, 2011 Tom Gaisser 6
South Pole Astro April 4, 2011 Tom Gaisser 7
Weather with Ice. Cube • Muon production samples stratospheric temperature – Higher T, lower r, more p± decay before interaction more m South Pole Astro April 4, 2011 Tom Gaisser 8
Solar & heliospheric physics • ~2 k. Hz rate per Ice. Top tank, now with 162 tanks – study of solar cosmic ray events & solar modulation with fine time resolution & spectral resolution 32 tanks in 2006 South Pole Astro April 4, 2011 Tom Gaisser Ap. J 689 (2008) L 65 -L 68 9
Energy range of atmospheric nm • Most events – 0. 3 to 10 Te. V – ECR ~ 3 to 100 Te. V/nucleon • Rate (>100 Te. V) – Prompt n (charm) – ~100’s per yr – Absorption in Earth distorts angular dist. South Pole Astro April 4, 2011 Tom Gaisser 10
Neutrino effective area ( P n ~ sn X R m ) • Rate: = ∫fn(En)Aeff(En)d. En • Earth absorption – Starts 10 -100 Te. V – Biggest effect near vertical – Higher energy n’s absorbed at larger angles South Pole Astro April 4, 2011 Tom Gaisser 11
Atmospheric muons in Ice. Cube Similar energy range to atmospheric n South Pole Astro April 4, 2011 Tom Gaisser 12
Primary composition with m & n • Calibration criterion: consistency of – Primary spectrum / composition – Spectrum & angular distribution of m and n • Interesting region for primary spectrum/composition – ATIC, CREAM, PAMELA • Spectra harder E > 200 Ge. V/A PAMELA, Adriani et al. , ar. Xiv: 1103. 4055 South Pole Astro April 4, 2011 Tom Gaisser 13
All-particle spectrum modeled with 3 populations & 5 groups of nuclei Primary spectrum & composition affect atmospheric neutrinos Spectrum of nucleons (Ge. V/A) E -2. 7 Realistic South Pole Astro April 4, 2011 Tom Gaisser 14
Spectrum/composition with Ice. Cube/Ice. Top < Pe. V • Threshold energy > Ee. V – < 300 Te. V • Maximum energy – Limited by km 2 size – Coincident events • A W = 0. 3 km 2 sr • Emax = Ee. V – Ice. Top only (q < 60 o) • A W = 3 km 2 sr • Emax = 3 Ee. V – In-ice trigger & reco • Emax = 3 Ee. V South Pole Astro April 4, 2011 Anchor to direct measurement of composition ~300 Te. V Tom Gaisser Look for transition to extra-galactic < Ee. V 15
Composition from Ice. Top, In-ice coincident events Muon multiplicity • hard to measure • Reconstruct muon bundle to get energy deposition by muons in deep Ice. Cube • Reconstruct surface shower to get Eprimary • Require consistency with angular distribution and m/e measured on the surface South Pole Astro April 4, 2011 Tom Gaisser Ice. Cube sims; Patrick Berghaus Muon energy deposition in Ice. Cube • is directly measured • has good sensitivity 16
Composition from Ice. Top, In-ice coincident events Patrick Berghaus, Sept 2009 --Ice. Cube collaboration mtg Good experimental correlation Simulations & study of systematics is in progress South Pole Astro April 4, 2011 Tom Gaisser 17
Recent data (June 2010, large, vertical event) South Pole Astro April 4, 2011 Tom Gaisser 18
Large, inclined event in Ice. Top-73 South Pole Astro April 4, 2011 Tom Gaisser 19
Current Ice. Top size spectrum Six months Ice. Top-73 2010/11 South Pole Astro April 4, 2011 Tom Gaisser 20
Extending the reach of Ice. Top • With present array we can use events reconstructed in deep ice that pass outside of Ice. Top • Two benefits: 1. Veto for horizontal GZK neutrino candidates 2. Spectrum / composition physics South Pole Astro April 4, 2011 Tom Gaisser 21
Ice. Top as a veto Present Ice. Top improves point source sensitivity by a factor of 2 for overhead sources South Pole Astro April 4, 2011 ~3 km Tom Gaisser 22
Proposal for RASTA • Radio Air Shower Test Array – Goal is to establish feasibility of radio air shower detection at South Pole • Proposal to be submitted to NSF June, 2011 – 3 yr study to confirm the concept South Pole Astro April 4, 2011 Tom Gaisser 23
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Summary comments • High rate of atmospheric m fine resolution for – Anisotropy – Temperature effects – Solar, heliospheric studies with Ice. Top • Primary spectrum & composition – To > 100 Te. V with atmospheric m, n – Ice. Top, Ice. Cube coincidenct events extend to Ee. V • Uniform acceptance from below knee to Ee. V • Look for transition to extra-galactic component E < Ee. V • (Auger &TA are lowering thresholds to do this) • Extend Ice. Top acceptance for veto and science – Use events with cores outside Ice. Top – Build RASTA South Pole Astro April 4, 2011 Tom Gaisser 30
Ice. Top • Two tanks per station for calibration, muon ID • High-gain, low-gain DOMs for dynamic range • Waveforms give some m/e discrimination at the surface (not yet implemented) • Calibration with few Ge. V muons Nov 23, 2007 Photo: James Roth, Dec 8, 2007 South Pole Astro April 4, 2011 Tom Gaisser 31
RASTA Symbiotic with ARA • Proposed radio air shower array on surface • Symbiotic with ARA South Pole Astro April 4, 2011 Tom Gaisser 32
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Extra slides South Pole Astro April 4, 2011 Tom Gaisser 34
Coincident event: June 2010 South Pole Astro April 4, 2011 Tom Gaisser 35
South Pole Astro April 4, 2011 Tom Gaisser 36 ISVHECRI - 2010
In-fill for overlap with direct measurements > 100 Te. V Response for Iron primaries Response for proton primaries 100 Te. V Single in-fill triangle Good response for p through Fe for 100 – 300 Te. V -- overlaps ATIC, TRACER, CREAM South Pole Astro April 4, 2011 Tom Gaisser 37
Composition from angular dependence of spectrum Reconstruct primary spectrum assuming primary Protons only … or … Iron only Protons showers more penetrating relatively greater contribution at large angle Fabian Kislat et al. , ICRC 2009 paper #0970 South Pole Astro April 4, 2011 Tom Gaisser 38
Composition-dependence: factor 2 - 3 between p and Fe T. Feusels, J. Eisch, C. Xu (Ice. Cube, ICRC 2009, paper 0518) South Pole Astro April 4, 2011 Tom Gaisser 39
Dec 13 to during. Mark transition from TICL to ICL Thanks Krasberg … South Pole Astro April 4, 2011 Tom Gaisser 40
Spectral Information • • South Pole Astro April 4, 2011 Tom Gaisser Excess count rate (averaged over approximately one hour near the peak of the event) as a function of pre-event counting rate. Each point represents one discriminator in one DOM. The higher count rate cluster comes from the SPE discriminators, the lower cluster from the MPE. Due to various technical issues, not all of the 64 DOMS have produced useful data at this time. Deconvolution of this relationship will result in an energy spectrum estimate. Excess flux increasing with count rate (i. e. decreasing with response energy) indicates that the flare spectrum is softer than the galactic cosmic ray spectrum that produces the background. It turns out that a linear fit to the average increase as a function of count rate is a good approximation. 41
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