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Lecture at the J. Stefan Institute Ljubljana within the course: 'Advanced particle detectors and data analysis' Hermann Kolanoski Humboldt-Universität zu Berlin and DESY Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 1

Lecture at the J. Stefan Institute Ljubljana within the course: 'Advanced particle detectors and data analysis' Hermann Kolanoski Humboldt-Universität zu Berlin and DESY Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 1

Overview of the lecture: – Part 1: Cosmic rays (CR) up to 10 18 eV (EeV) – Part 2: Neutrinos as Cosmic Ray messengers Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 2

Part 1 – Discovery of Cosmic rays (CR) – How to measure CR – spectrum and composition – Below the knee: direct measurements – Above the knee: Extensive air showers (EAS) – PeV-EeV: Spectrum and Composition – Anisotropy – Possible sources Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 3

Cosmic Rays 100 years after their discovery not yet understood ion pairs / (cm 3 s) Kernfragmente Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 4

Extended Air Showers (EAS) 1938 Pierre Auger discovered EAS with 2 Geiger-Müller counters in coincidence, Auger and his colleagues detected extensive air showers. Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 5

Zwicky’s proposal for the CR Origin “Cosmic rays are caused by exploding stars which burn with a fire equal to 100 million suns and then shrivel from ½ million mile diameters to little spheres 14 miles thick.” In Los Angeles Times, Jan. 1934 Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 6

Useful Cosmic Rays π Motor of Evolution The cradle of particle physics µ anti-electron e Testing detectors, educational outreach, … C-14 dating educational outreach, … Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 7

Charged Cosmic Ray Spectrum Flux (m 2 sr s GeV) -1 ~ 32 decades ⇒ very different detection methods ~ 32 decades very different detector sizes Where and how are the highest energies produced??? Galactic and/or extragalactic? LHC(pp) LHC(p) What is the composition? Is there an energy cut-off? Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 8

Balloon Experiments • volume up to 1 Million m 3 • pay load up to 3 to • height up to 40 km. • atmospheric depth 3-5 g/cm 2 • compare to λ int (proton) = 90 g/cm 2 example: Helium buoyancy of 1 kg/m 3 on ground ⇒ for a load of 2000 kg need 2000 m 3 helium ⇒ 400 000 m 3 at height of 5 g/cm 2 Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 9

Balloon: Detectors Identification without magnet: Transition Radiation X-Ray Intensity ~ γ = E/Mc 2 ε 1 ε 2 ε 1 ε 1 ε 2 wire chamber Energy Charge Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 10

CR Composition up to ~100TeV 1 TeV 1 PeV ~ GeV ~GeV ◊ CR 1 TeV (CREAM) ◊ ◊ ◊ ◊ ◊ ◊ ◊ ◊ ◊ ◊ ◊ Filled due to interactions Li, Be, B surpressed in fusion accelerated about 10 7 years ago charged particles stay in galaxy due to magnetic field Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 11

Extensive Air Showers Flux (m 2 sr s GeV) -1 Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 12

Air Shower Development Atmospheric depth in g/cm 2 : ∞ ∫ = ρ ≈ X ( h ) ( z ) dz p ( h ) / g h Shower age : 3 = s 2 X + max 1 X 0 ≤ 𝑡 𝑌 ≤ 3 𝑡 𝑌 𝑛𝑛𝑛 = 1 Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 13

Longitudinal Shower Profile Gaisser-Hillas Formula: N e,max , X max , X 1 , Λ are parameters Λ≈ 70 g/cm 2 is an effective rad. length e.g.: at 100 PeV about 10 7 particles on sea level. Shower profile can be seen with Cherenkov and fluorescence telescopes. But mostly air shower detectors are calorimeters with only one readout plane. Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 14

Lateral Distribution Functions NKG: 𝑂 𝑓 ( 𝑌 ) number of particles at depth 𝑌 𝑡 = 3/(1 + 2 𝑌 𝑛𝑛𝑛 / 𝑌 ) shower age Molière radius normalization Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 15

Shower Physics and Interaction Models • hadronic interaction models: SYBILL, QGSJET, EPOS • FLUKA for lower energies • Tuning with LHC Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 16

Coverage of LHC Detect ors p+p @ 14 TeV particle flow energy flow rapidity ➙ energy & particle flow at all rapidities p T , σ Tot , σ inel , σ diffr , ... Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 17

Improvements in Models thanks to LHC Before LHC Now X max model uncertainties improved from ~ 50 g/cm 2 to ~ 20 g/cm 2 18

p-Air Cross-Section from X max distribution ΔX 1 X 1 : point of 1st interaction Data: 10 18 eV < E < 10 18.5 eV ΔX max = ΔX 1 Λ int In practice: σ p-Air by tuning models to describe Λ seen in data 𝜏 𝑞−𝑛𝑏𝑏 = 𝑜 𝑛𝑏𝑏 Difficulties: • mass composition can alter Λ 𝜇 𝑏𝑗𝑗 • fluctuations in Xmax • experimental resolution ~ 20 g/cm 2 19

p- Air and pp Cross section @ √s=57 TeV Auger Collaboration, PRL 109, 062002 (2012) Conversion from p-air to p-p cross section by Glauber-approach σ p-Air = (505 ± 22 stat ( +26 ) sys ) mb –34 Auger inel LHC σ pp = [92 ± 7 stat ( +9 ) sys ± 7.0 Glauber ] mb –11 tot σ pp = [133 ± 13 stat ( +17 ) sys ± 16 Glauber ] mb –20 20

Detecting Extensive Air Showers Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 21

Detector sizes very high particle densities in air showers  take only samples Tibet AS- γ KASCADE distance 7.5 m distance 13 m 40000 m 2 size 40000 m 2 size energies 10 TeV – 1 PeV energies 100 TeV – 10 PeV distance 1500 m Pierre Auger distance 125 m 3000 km 2 size 1 km 2 size energies EeV – 100 EeV energies PeV – EeV IceTop Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 22

Sampling Detectors Sampling on the surface scintillation counters water/ice Cherenkov detectors measure: number of particles measure: calorimetric energy Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 23

Sampling of longitudinal shower profile imaging Cherenkov non-imaging Cherenkov fluorescence telescope Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 24

muon detectors GeV muons from shower products TeV muons from first interaction, near shower axis muon number is composition sensitive: for HE nucleus each nucleon interacts independently ⇒ higher hadron multiplicity ⇒ higher meson decay rate ⇒ higher muon rate Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 25

Sampling distance • you need large areas, Estimate for IceTop: • but need not completely covered Effective Lateral Shower Size because of high particle densities Energy dependence of the radius above which signals drops in a 3-m 2 -detector below 0.2 VEM for O(m 2) detector find range of • 1000 m suitable signals, see  1000 • chose sampling distance such that 250 m R [m] that detector does not limit energy 100 m and angle resolution 100 92 TeV 70 PeV 1.1 PeV 10 4 5 6 7 8 9 log(E/GeV) Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 26

Air Shower Reconstruction s  ( , x , t ) N signals i i i ⇒ shower front θ • shower direction: θ , φ y c • shower centre x c , y c x c • shower size ⇒ E 0 lateral distribution of signals ( with mass hyp.) • shower age: ⇒ X max S 125 reference signal size at R=125 m Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 27

Detectors in the PeV to EeV Range Typical size ~ 1 km 2 e.g. Kaskade-Grande, Tunka, IceTop, Kaskade-Grande Tunka What limits a 1 km 2 detector? IceTop at 1 EeV: F=1.5 × 10 -21 (m 2 sr s GeV) -1 for ∆ log E = 0.1; ∆Ω =1.8 sr ( θ <45 ° ); A=1 km 2 you get about 8 events per year Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 28

IC-86 IceCube Detector IC-79 2011 IC-59 2010 2009 Detector Completion Dec 2010 IC-1 IC-40 2005 2008 IC-9 IC-22 2006 2007 CR Analyses • air showers in IceTop • muon (bundle)s in IceCube • atm. neutrinos in IceCube • IceCube - IceTop coinc. IceCube with IceTop is a 3-dim Air Shower Detector unprecedented volume Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 29

Aerial view of IceCube/IceTop 10 m 125 m Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 30

DOM – Digital Optical Module pressure glas sphere junction cable harness elektronics: high voltage, digitalization, data transfer photomultiplier = light sensor Ø 32cm Ljubljana, March 2015 H.Kolanoski - Lecture 'Origin of Cosmic Rays' - 1 31