Martin A. Pomerantz

Cosmic Rays: Elementary Particles in Nature by Thomas K. Gaisser

Themes The atomic view of science Cosmic rays & particle physics: 3 examples Neutrinos Neutrinos Antiprotons Antiprotons Air showers Air showers Particle astrophysics in Antarctica South Pole Air Shower Experiment (SPASE) South Pole Air Shower Experiment (SPASE) IceCube IceCube

2400 years of elementary particles Democritus c B.C. Atomic theory of matter Atomic theory of matter Not continuous elements (fire, air, earth and water) but Not continuous elements (fire, air, earth and water) but Indivisible atoms ~ elementary particles Indivisible atoms ~ elementary particles Their interactions, combinations, motions explain everything Their interactions, combinations, motions explain everything Epicurus c Lucretius (Rome, c ) de Rerum Natura de Rerum Natura “least parts” ~ quarks “least parts” ~ quarks Epicurus

Levels of structure Molecules: combinations of atoms 6CO 2 + 6H 2 O + light  C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + light  C 6 H 12 O 6 + 6O 2 Produce wood (C 6 H 10 O 5 ) by taking carbon out of the air and water from the ground Produce wood (C 6 H 10 O 5 ) by taking carbon out of the air and water from the ground Atoms: compact nucleus with electron cloud p + Mn  p + e - + Mn +  p + Mn + x-ray p + Mn  p + e - + Mn +  p + Mn + x-ray electron ejected; recombination x-ray emitted electron ejected; recombination x-ray emitted Nuclei: Z protons and (N = A - Z) neutrons Nucleons: p = [uud]; n = [udd] Epicurean “atom” Minimal parts

Beta-decay and the neutrino Nuclear  -decay A(Z,N)  A(Z+1,N-1) + e - + e A(Z,N)  A(Z+1,N-1) + e - + e n  p + e - + e ( n = [udd]  p = [uud] ) n  p + e - + e ( n = [udd]  p = [uud] ) d  u + e - + e d  u + e - + e Neutrino (symbol ) hypothesized by Pauli (1930) to conserve energy hypothesized by Pauli (1930) to conserve energy named by Fermi (1933) “little neutral one” named by Fermi (1933) “little neutral one” first detected 1956 ( e from nuclear reactor) by Cowan and Reines first detected 1956 ( e from nuclear reactor) by Cowan and Reines 3 neutrino flavors: e,  and  3 neutrino flavors: e,  and 

Elementary Particle Physics (a.k.a. High Energy Physics) Study particles by collisions: p + p  ? E = mc 2 : When E >> mc 2, E  mass on large scale When E >> mc 2, E  mass on large scale then ? = many particles then ? = many particlesExamples: p + p  p + n +  + followed by (  +   +  ) p + p  p + n +  + followed by (  +   +  ) p + p  p + p + p + p (p = antiproton) p + p  p + p + p + p (p = antiproton) p + 14 N  200 p + 20 K + … p + 14 N  200 p + 20 K + …

Macroscopic collisions  P + P  P + P + P + P Warning: This is a flawed analogy because cars are highly composite objects

What are Cosmic Rays? Naturally occurring particles (protons and nuclei) having very high energies From sources far outside the solar system Discovered nearly a century ago Studied with detectors on balloons and spacecraft as well as from the ground Positron, pion, kaon were all discovered by observations of cosmic-ray interactions in the atmosphere

-mass and flavor oscillations --a recent discovery about particles using interactions of cosmic rays -mass and flavor oscillations --a recent discovery about particles using interactions of cosmic rays Cosmic-ray neutrinos p + air   + particles p + air   + particles    +     +    e +  + e   e +  + e Atmospheric n anomaly  / e  1 (instead of 2)  / e  1 (instead of 2) upward  < downward  upward  < downward  Explanation:  Explanation:    Implies have mass > 0 Artist’s view of Super-K Detector: 11,000 20” phototubes viewing 40,000 tonnes (10 million gallons) of water in a mine in Japan

Pictures of Super-K Top left: Super-K half full (1996) Right: unpacking the PMTs Bottom: Super-K after accident (Nov. 2001) Detector is currently being rebuilt

Cherenkov radiation: signals in Super-Kamiokande Sonic boom (from object faster than speed of sound) is analogous to Cherenkov radiation by a charged particle moving faster than speed of light in a medium

Cosmic Gall by John Updike Neutrinos, they are very small. Neutrinos, they are very small. They have no charge and have no mass They have no charge and have no mass And do not interact at all. And do not interact at all. The earth is just a silly ball The earth is just a silly ball To them, through which they simply pass, To them, through which they simply pass, Like dustmaids through a drafty hall Like dustmaids through a drafty hall Or photons through a sheet of glass. Or photons through a sheet of glass. They snub the most exquisite gas, They snub the most exquisite gas, Ignore the most substantial wall, Ignore the most substantial wall, Cold-shoulder steel and sounding brass, Cold-shoulder steel and sounding brass, Insult the stallion in his stall, Insult the stallion in his stall, And scorning barriers of class, And scorning barriers of class, Infiltrate you and me! Like tall Infiltrate you and me! Like tall And painless guillotines, they fall And painless guillotines, they fall Down through our heads into the grass. Down through our heads into the grass. At night, they enter at Nepal At night, they enter at Nepal And pierce the lover and his lass And pierce the lover and his lass From underneath the bed - you call From underneath the bed - you call It wonderful; I call it crass. It wonderful; I call it crass. from Telephone Poles and Other Poems by John Updike © Knopf 1963 Solar Neutrinos Sudbury Neutrino Observatory Art McDonald gave Swann lecture at Bartol/DPA in February They also oscillate: e  [    ] hardly (Gell-Mann) little

High-energy accelerators Accelerator labs  high energy particles Cosmic accelerators  cosmic rays What are the sources? What are the sources? How are the particles accelerated? How are the particles accelerated? How do they get here? How do they get here? What happens on the way? What happens on the way?

Fermilab’s Tevatron ring is 4 miles around Particle accelerators CERN site with LEP tunnel & L3 detector

Cosmic accelerators (some supernova remnants in our galaxy) SN1987A SN1054 Circa 1650 (Cas-A) SN1572

Really Big Cosmic accelerators: jets in active galaxies VLA image of Cygnus A 20 TeV gamma rays observed Higher energies obscured by IR light but the universe is transparent to but the universe is transparent to

Primary cosmic-ray antiprotons p + interstellar gas  p + … Issues: Are there exotic sources? Are there exotic sources? Probe the heliosphere Probe the heliosphere Results: p/p ratio consistent with origin in interstellar gas consistent with origin in interstellar gas Predicted change agrees with Bartol group’s prediction for 2000 solar maximum based on large-scale structure of solar wind and its magnetic field Predicted change agrees with Bartol group’s prediction for 2000 solar maximum based on large-scale structure of solar wind and its magnetic field

Interactions at ultra-high energy make air showers Intensity is very low ~20 per hour per acre for E = 2 million x mc 2 (~E of biggest accelerator) ~20 per hour per acre for E = 2 million x mc 2 (~E of biggest accelerator) ~ 1 per sq. km per century at E = 200 trillion x mc 2 (most energetic cosmic ray) ~ 1 per sq. km per century at E = 200 trillion x mc 2 (most energetic cosmic ray) Use large ground arrays Several acres … Several acres … Several thousand sq. miles Several thousand sq. miles Schematic view of air shower detection: ground array and Fly’s Eye

Auger detector Under construction in Argentina Jim Cronin, Alan Watson, Jim Beatty …

SPASE-AMANDA SPASE-1, Hillas, Pomerantz, Watson Hillas, Pomerantz, Watson (Leeds-Bartol) (Leeds-Bartol) SPASE-2, 1996 – Current Bartol experiment Current Bartol experiment TKG, Watson, Evenson, Stanev, Tilav, Bai... TKG, Watson, Evenson, Stanev, Tilav, Bai... Coincidences with AMANDA Coincidences with AMANDA AMANDA is a neutrino telescope

McMurdo

Amundsen-Scott South Pole Station

Optical sensor Martin A. Pomerantz Observatory (MAPO)

The IceCube Collaboration Institutions: 11 US and 9 European institutions (most of them are also AMANDA member institutions) (most of them are also AMANDA member institutions) 1.Bartol Research Institute, University of Delaware 2.BUGH Wuppertal, Germany 3.Universite Libre de Bruxelles, Brussels, Belgium 4.CTSPS, Clark-Atlanta University, Atlanta USA 5.DESY-Zeuthen, Zeuthen, Germany 6.Institute for Advanced Study, Princeton, USA 7.Dept. of Technology, Kalmar University, Kalmar, Sweden 8.Lawrence Berkeley National Laboratory, Berkeley, USA 9.Department of Physics, Southern University and A\&M College, Baton Rouge, LA, USA 10.Dept. of Physics, UC Berkeley, USA 11.Institute of Physics, University of Mainz, Mainz, Germany 12.Dept. of Physics, University of Maryland, USA 13.University of Mons-Hainaut, Mons, Belgium 14.Dept. of Physics and Astronomy, University of Pennsylvania, Philadelphia, USA 15.Dept. of Astronomy, Dept. of Physics, SSEC, PSL, University of Wisconsin, Madison, USA 16.Physics Department, University of Wisconsin, River Falls, USA 17.Division of High Energy Physics, Uppsala University, Uppsala, Sweden 18.Fysikum, Stockholm University, Stockholm, Sweden 19.University of Alabama, Tuscelosa, USA 20.Vrije Universiteit Brussel, Brussel, Belgium

IceCube 1400 m 2400 m AMANDA South Pole IceTop Skiway 80 Strings 4800 PMT Instrumented volume: 1 km3 (1 Gt) IceCube is designed to detect neutrinos of all flavors at energies from 10 7 eV (SN) to eV Motivation: weakly interacting n can emerge from deep inside a source Need BIG detector

E µ = 10 TeVE µ = 6 PeV Muon Events Measure energy by counting the number of fired PMT. (This is a very simple but robust method) (This is a very simple but robust method)

Future prospects The IceCube neutrino telescope--goals: Find high-energy neutrinos: unique probes of cosmic accelerators--see brochures Find high-energy neutrinos: unique probes of cosmic accelerators--see brochures Measure primary cosmic rays to > billion mc 2 with a three-dimensional air shower detector Measure primary cosmic rays to > billion mc 2 with a three-dimensional air shower detector A multi-year project (10-15 years) Many high-level reviews passed Many high-level reviews passed First year funding in NSF plan for current year First year funding in NSF plan for current year We are working hard to make this happen We are working hard to make this happen

South Pole Air Shower Experiment Sunset, March 21, 2002 Photo of electronics tower by Katherine Rawlins

Cosmic rays in Antarctica May 2001 Awards Day at which Martin Pomerantz received an honorary degree from UD

Fission, fusion and neutrinos Example of nuclear fission Example of nuclear fission n + U 235  Xe Sr n  n + U 235  … n + U 235  Xe Sr n  n + U 235  … daughter nuclei multi-  -decay  multi- e daughter nuclei multi-  -decay  multi- e 1956: Cowan & Reines detect e at reactor 1956: Cowan & Reines detect e at reactor Nuclear fusion (e.g. in the Sun) p + p  2 H + e (neutrino, not anti-neutrino ) p + p  2 H + e (neutrino, not anti-neutrino ) 2 H + p  3 He +  2 H + p  3 He +  3 He + 3 He  4 He + 2p 3 He + 3 He  4 He + 2p 2002 SNO experiment solves solar problem 2002 SNO experiment solves solar problem