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What is matter made of?. Your basic matter is made of nuclei (protons and neutrons) surrounded by electrons All very small- zillions in dust mote. Particle Physics. E,n,p- what else? Zoo of hundreds of particles Made in collisions Exist for short times, then decay or collide

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What is matter made of l.jpg
What is matter made of?

  • Your basic matter is made of nuclei (protons and neutrons) surrounded by electrons

  • All very small- zillions in dust mote


Particle physics l.jpg
Particle Physics

  • E,n,p- what else?

  • Zoo of hundreds of particles

  • Made in collisions

  • Exist for short times, then decay or collide

  • Cosmic Rays and Accelerators


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The Standard Model

  • 12 particles

  • Four Forces- strong, weak, E+M, gravity

  • Antiparticles

  • Quarks come in 3’s or q-antiq pairs ONLY

  • Leptons have “conserved type”


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Four Forces

  • Strong - gluons hold quarks together

  • EM- photons = light

  • Weak- W and Z- q’s change flavor, leptons and neutrinos

  • Gravity-???


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Neutrinos

  • 3 types- nu-e, nu-mu, nu-tau

  • More or less massless (maybe)

  • only interact rarely and weakly with matter


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Neutrino Problem

Calculation wrong? No

Experiment wrong? No

Something happens to neutrinos as they travel!

Does nu-e turn into nu-mu?

  • Can calculate solar neutrino flux

  • Experiments find about half as much

  • Same for CR-air nu-mu/nu-e ratio

  • Several experiments-same answer

  • ?? Confusion ??


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Dark Matter Problem

  • Astronomers can only identify 20% of the mass in a galaxy

  • Is the rest neutrinos? Maybe...


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Minos

  • Make (mostly) nu-mu beam at FNAL

  • measure nu-mu/nu-e ratio there

  • measure it again in Soudan, MN

  • compare and see if it changes


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Making Neutrino Beams

  • Fermilab makes a beam of protons

  • Hits a metal target, makes pions and stuff

  • Focus pions (u-ubar), point at Soudan

  • Pions decay to muons and nu-mu

  • muons hit rock, stop

  • nu-mus continue under Wisconsin to Soudan


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Detectors

  • Near Detector in IL

  • Far Detector, aka Minos at Soudan

  • As similar as possible

  • Far detector is VERY large (7,000 tons)

  • neutrinos interact weakly- need lots of stuff


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Minos Detector

  • Iron sheets for mass

  • Plastic Scintillator to detect particles

  • Plastic emits light when particle goes through

  • Light is carried out to photodetectors

  • Data-> Computers


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Minos Data

  • We see neutrinos interact with nuclei

  • Remnants splatter

  • Muons go long ways, make “tails”

  • Electrons make much shorter events

  • Count nu-mu/nu-e


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Backgrounds

  • Cosmic Rays- constant shower of muons from CRs

  • Hide underground

  • Soudan State Park has a 2341 feet deep hole

  • we’ve worked there before


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Soudan State Park

  • Iron mine given to state in 1962

  • Tours all summer

  • Maintain lowest level

  • Historic elevator

  • Nice people!

  • Summer is pretty...


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Soudan 2

  • Previous experiment

  • Looking for proton decay

  • sees neutrinos

  • next door to Minos


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Minos Collaboration

  • 200+ people from 3 continents

  • UMN, Argonne, Caltech, Indiana, Harvard, Tufts

  • Oxford, Cambridge, RAL, Sussex, Greece

  • ~25 grad students


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Minos Status

  • Far Det is done, detects neutrinos

  • Near Det construction starts in April

  • First neutrinos in 2005


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Silliness

  • Neutrino Lass!


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