Physics of Neutino Factries and Muon Coliders

Quarknet Presentation Gail G. Hanson August 8, 2008 • WHAT IS A MUON?

• WHAT IS A NEUTRINO?

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Quarknet Presentation, August 8, 2008 Gail G. Hanson 2 MUONS

• A MUON (µ) IS LIKE AN ELECTRON, ONLY 200 TIMES HEAVIER.

• THE ELECTRON (e) IS THE LIGHTEST CHARGED PARTICLE.

• THE ELECTRON CANNOT DECAY SINCE A PARTICLE CAN DECAY ONLY TO PARTICLES LIGHTER THAN ITSELF, AND CHARGE MUST BE CONSERVED. Quarknet Presentation, August 8, 2008 Gail G. Hanson 3 • SINCE THE MUON IS HEAVIER THAN THE ELECTRON, IT CAN DECAY INTO IT:

! ! µ " e #e#µ

• THE EXTRA PARTICLES ARE NEUTRINOS.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 4 NEUTRINOS

• NEUTRINOS WERE FIRST SEEN (OR NOT SEEN) IN NUCLEAR DECAYS (BETA DECAY) IN WHICH AN EXTRA INVISIBLE MASSLESS PARTICLE WAS NEEDED TO DESCRIBE THE OBSERVATIONS:

60 60 * " Co ! Ni e #e

Quarknet Presentation, August 8, 2008 Gail G. Hanson 5 NEUTRINOS

• NEUTRINOS (ν), THEN, ARE INVISIBLE MASSLESS PARTICLES. • LATER IT WAS FOUND THAT NEUTRINOS COME IN THREE FLAVORS:

νe νµ ντ ( e − ) ( µ − ) ( τ − )

Quarknet Presentation, August 8, 2008 Gail G. Hanson 6 NEUTRINOS

• (THE TAU (τ) IS A THIRD MEMBER OF THIS FAMILY, LIKE A MUON, BUT EVEN HEAVIER.)

• THE FLAVOR, WHICH IS CALLED LEPTON NUMBER, IS CONSERVED.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 7 NEUTRINOS • NOW JUST WHEN PHYSICISTS THOUGHT THEY HAD ALL OF THIS UNDERSTOOD, TWO PUZZLING OBSERVATIONS WERE MADE….

Quarknet Presentation, August 8, 2008 Gail G. Hanson 8 DEFICIT OF SOLAR NEUTRINOS

• ELECTRON NEUTRINOS (νe) ARE PRODUCED BY THE NUCLEAR FUSION REACTIONS RESPONSIBLE FOR THE ENERGY OF THE SUN.

• THEORETICAL PREDICTIONS WERE MADE FOR THE NUMBER THAT SHOULD BE OBSERVED ON EARTH − THE “SOLAR MODEL.”

Quarknet Presentation, August 8, 2008 Gail G. Hanson 9 • OBSERVATIONS OF THESE ELECTRON NEUTRINOS DID NOT AGREE WITH THE PREDICTIONS − ONLY ABOUT ONE-HALF THE PREDICTED NUMBER WERE OBSERVED (FIRST BY RAY DAVIS − 2002 NOBEL PRIZE − AT THE HOMESTAKE MINE IN SOUTH DAKOTA).

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Quarknet Presentation, August 8, 2008 Gail G. Hanson 10 DEFICIT OF ATMOSPHERIC NEUTRINOS

• AN EXPERIMENT IN JAPAN, KAMIOKANDE, CONFIRMED DAVIS’S RESULT (MASATOSHI KOSHIBA − 2002 NOBEL PRIZE). • KAMIOKANDE, FOLLOWED BY SUPERKAMIOKANDE, ALSO OBSERVED A DEFICIT OF MUON NEUTRINOS (νµ), PRODUCED BY COSMIC RAYS IN THE EARTH’S ATMOSPHERE.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 11 NEUTRINO OSCILLATIONS • BOTH OF THESE OBSERVATIONS CAN BE EXPLAINED IF THE ELECTRON NEUTRINOS FROM THE SUN AND THE MUON NEUTRINOS PRODUCED BY COSMIC RAYS CHANGE TO ANOTHER FLAVOR OF NEUTRINO BEFORE REACHING THE EARTH.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 12 NEUTRINO OSCILLATIONS • SOLAR NEUTRINOS:

νe νµ or ντ

• ATMOSPHERIC NEUTRINOS:

νµ ντ

• NEUTRINOS OSCILLATE FROM ONE FLAVOR TO ANOTHER

Quarknet Presentation, August 8, 2008 Gail G. Hanson 13 NEUTRINO OSCILLATIONS • HOWEVER, FOR OSCILLATION TO OCCUR 2 2 2 Δm = m (ν2) − m (ν1) CANNOT BE 0 FOR THE PAIRS OF NEUTRINOS INVOLVED. • THIS MEANS THAT SOME NEUTRINOS MUST HAVE MASS! ?

Quarknet Presentation, August 8, 2008 Gail G. Hanson 14 MUON COLLIDERS

• MEANWHILE, OTHER PHYSICISTS WERE DEVELOPING STORAGE RING ACCELERATORS IN WHICH POSITIVE AND NEGATIVE MUONS WOULD COLLIDE. • COLLIDING µ+ AND µ− BEAMS OFFERED THE POSSIBILITY OF SMALLER, CHEAPER HIGH ENERGY COLLIDERS, BECAUSE MUONS RADIATE LESS THAN ELECTRONS.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 15 COMPARISON OF HIGH ENERGY COLLIDERS

Quarknet Presentation, August 8, 2008 Gail G. Hanson 16 HIGGS FACTORY

µ+ µ−

Quarknet Presentation, August 8, 2008 Gail G. Hanson 17 NEUTRINO FACTORY

FIRST STEP TOWARDS A MUON COLLIDER:

• ONE MUON BEAM IN A STORAGE RING.

• AN INTENSE NEUTRINO BEAM FROM THE MUON DECAYS .

• A NEUTRINO FACTORY!

Quarknet Presentation, August 8, 2008 Gail G. Hanson 18 NEUTRINO FACTORY

(νµ, νe)

µ− Quarknet Presentation, August 8, 2008 Gail G. Hanson 19 NEUTRINO FACTORY

• NO OTHER COMPARABLE SOURCE OF ELECTRON NEUTRINO OR ELECTRON ANTINEUTRINO BEAMS (νe OR ! e ).

• CONVENTIONAL NEUTRINO BEAMS ARE + + MUON NEUTRINOS (FROM π µ νµ).

Quarknet Presentation, August 8, 2008 Gail G. Hanson 20 HOW TO MAKE A MUON BEAM

• A MUON BEAM IS MADE FROM DECAYS " " OF PIONS ( ! # µ $ µ ), WHICH HAVE BEEN PRODUCED FROM PROTONS STRIKING A TARGET. • ONE MAJOR PROBLEM IS HOW TO MAKE THE MUON BEAM NARROW − QUICKLY, BEFORE THE MUONS DECAY. THIS IS CALLED COOLING THE BEAM.

Quarknet Presentation, August 8, 2008 Gail G. Hanson 21 INTERNATIONAL MUON IONIZATION COOLING EXPERIMENT (MICE) AT RAL (U.K.) Experimental demonstration of ionization cooling

Quarknet Presentation, August 8, 2008 Gail G. Hanson 22 πMICEνµ Quarknet Presentation, August 8, 2008 Gail G. Hanson 23