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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. 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?

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  1. 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

  2. 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

  3. 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”

  4. Four Forces • Strong - gluons hold quarks together • EM- photons = light • Weak- W and Z- q’s change flavor, leptons and neutrinos • Gravity-???

  5. Neutrinos • 3 types- nu-e, nu-mu, nu-tau • More or less massless (maybe) • only interact rarely and weakly with matter

  6. 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 ??

  7. Dark Matter Problem • Astronomers can only identify 20% of the mass in a galaxy • Is the rest neutrinos? Maybe...

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. Soudan State Park • Iron mine given to state in 1962 • Tours all summer • Maintain lowest level • Historic elevator • Nice people! • Summer is pretty...

  15. Soudan 2 • Previous experiment • Looking for proton decay • sees neutrinos • next door to Minos

  16. Minos Collaboration • 200+ people from 3 continents • UMN, Argonne, Caltech, Indiana, Harvard, Tufts • Oxford, Cambridge, RAL, Sussex, Greece • ~25 grad students

  17. Minos Status • Far Det is done, detects neutrinos • Near Det construction starts in April • First neutrinos in 2005

  18. Silliness • Neutrino Lass!

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