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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
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
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
the standard model
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”
four forces
Four Forces
  • Strong - gluons hold quarks together
  • EM- photons = light
  • Weak- W and Z- q’s change flavor, leptons and neutrinos
  • Gravity-???
neutrinos
Neutrinos
  • 3 types- nu-e, nu-mu, nu-tau
  • More or less massless (maybe)
  • only interact rarely and weakly with matter
neutrino problem
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 ??
dark matter problem
Dark Matter Problem
  • Astronomers can only identify 20% of the mass in a galaxy
  • Is the rest neutrinos? Maybe...
minos
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
making neutrino beams
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
detectors
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
minos detector
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
minos data
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
backgrounds
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
soudan state park
Soudan State Park
  • Iron mine given to state in 1962
  • Tours all summer
  • Maintain lowest level
  • Historic elevator
  • Nice people!
  • Summer is pretty...
soudan 2
Soudan 2
  • Previous experiment
  • Looking for proton decay
  • sees neutrinos
  • next door to Minos
minos collaboration
Minos Collaboration
  • 200+ people from 3 continents
  • UMN, Argonne, Caltech, Indiana, Harvard, Tufts
  • Oxford, Cambridge, RAL, Sussex, Greece
  • ~25 grad students
minos status
Minos Status
  • Far Det is done, detects neutrinos
  • Near Det construction starts in April
  • First neutrinos in 2005
silliness
Silliness
  • Neutrino Lass!
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