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Neutrino Physics - Lecture 4

Neutrino Physics - Lecture 4. Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068, elliotts@lanl.gov. Lecture 4 Outline. Neutrinos from the Sun The neutrinos Past experiments What we know and what we want to learn. Cl Results. Expect 7.5 SNU. 2.56 ± 0.16 ± 0.16 SNU.

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Neutrino Physics - Lecture 4

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  1. Neutrino Physics - Lecture 4 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068, elliotts@lanl.gov

  2. Lecture 4 Outline • Neutrinos from the Sun The neutrinos Past experiments What we know and what we want to learn Steve Elliott, UNM Seminar Series

  3. Cl Results Expect 7.5 SNU 2.56 ± 0.16 ± 0.16 SNU Steve Elliott, UNM Seminar Series

  4. SAGE and Gallex (GNO) • 71Ga(e,e)71Ge • 71Ge has 11.4 day half life. • Expose Ga to neutrinos • Extract Ge and count via its decay • Decays of 71Ge are by electron capture: the signature is the 1.2 or 10.4 keV x rays, Auger electrons Steve Elliott, UNM Seminar Series

  5. SAGE Operations Add carrier to Ga. After about 3-4 weeks, extract Ge carrier and solar neutrino induced Ge. Synthesize counter gas and fill proportional counter. Count sample for about 6 months. Steve Elliott, UNM Seminar Series

  6. Map to SAGE Steve Elliott, UNM Seminar Series

  7. Baksan Valley, UG Laboratory Steve Elliott, UNM Seminar Series

  8. Source Calibration 92.4% enriched in 50Cr 512.7 g of Cr Irradiated for ~3 mnths 517 kCi activity Steve Elliott, UNM Seminar Series

  9. Reactor Layout 10 reactors Each can hold 8 tons of Ga Kept warm so Ga is liquid Steve Elliott, UNM Seminar Series

  10. Proportional Counters • R: recombination • IC: ionization chamber • PC: proportional chamber • GC: Geiger counter • D: continuous discharge D IC GC Collected Ions PC R Voltage Steve Elliott, UNM Seminar Series

  11. Proportional Counter Spectrum Steve Elliott, UNM Seminar Series

  12. Results - Solar Rate Each run saw about 6 signal Events. Expect 128 SNU Steve Elliott, UNM Seminar Series

  13. Gran Sasso Italy: Not too far from Rome Steve Elliott, UNM Seminar Series

  14. GNO Layout Steve Elliott, UNM Seminar Series

  15. GALLEX Results Expected 128 SNU Steve Elliott, UNM Seminar Series

  16. Kamiokande & SuperK • Elastic scattering of e- in a large water detector • Mostly sensitive to e because CC cross section is about 6x higher than NC Steve Elliott, UNM Seminar Series

  17. Cherenkov Radiation “Electrons in the atoms of the medium will be displaced and polarized by the passing EM field of a charged particle. Photons are emitted as an insulator's electrons restore themselves to equalibrium after the disruption has passed. (In a conductor, the EM disruption can be restored without emitting a photon.) In normal circumstances, these photons destructively interfere with each other and no radiation is detected. However, when the disruption travels faster than the photons themselves travel, the photons constructively interfere and intensify the observed radiation.” Wikipedia Steve Elliott, UNM Seminar Series

  18. Photomultiplier Tubes Steve Elliott, UNM Seminar Series

  19. SuperKamiokande Characteristics • 50,000 t water • 11,146 20” pmt • 1,885 8” pmt Steve Elliott, UNM Seminar Series

  20. SuperK Data Steve Elliott, UNM Seminar Series

  21. SNO • ES, CC, and NC • CC: d(e, pp)e- • Sensitive only to e • NC: d(x, np)x • Sensitive to all x • NC/CC ratio Steve Elliott, UNM Seminar Series

  22. SNO’s Location < 100 m/day Steve Elliott, UNM Seminar Series

  23. The SNO Detector 9438 inward & 91 outward With concentrators = 54% coverage 2039 m to surface 1011 m to Sun Control room Vectran support ropes 12 m diameter acrylic vessel Urylon liner Norite rock Support structure for 9500 PMTs, concentrators 1000 tonnes heavy water 5300 tonnes light water 1700 tonnes light water Steve Elliott, UNM Seminar Series

  24. SNO Calibration • Electronics Calibrations • Built-in programmable pulsers • Optical Calibrations • Laser ball: attenuation, scattering, reflectivity • Energy Calibrations • 16N source: 16O(n,p)16N* • b-tagged 6.1-MeV g source • 8Li Source: e- spectrum similar to 8B • 252Cf source: fission neutron source • Encapsulated U/Th source (low-E g’s) • 3H(p, g)4He: 19.8-MeV g • Triggered U: Th sources (low-E g’s) • Michel electrons Steve Elliott, UNM Seminar Series

  25. An example Event: atmospheric neutrino Steve Elliott, UNM Seminar Series

  26. SNO data Radius of event vertex Angle with Sun Steve Elliott, UNM Seminar Series

  27. Event Energy Steve Elliott, UNM Seminar Series

  28. NC vs. CC Steve Elliott, UNM Seminar Series

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