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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 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 Steve Elliott, UNM Seminar Series
Cl Results Expect 7.5 SNU 2.56 ± 0.16 ± 0.16 SNU Steve Elliott, UNM Seminar Series
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
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
Map to SAGE Steve Elliott, UNM Seminar Series
Baksan Valley, UG Laboratory Steve Elliott, UNM Seminar Series
Source Calibration 92.4% enriched in 50Cr 512.7 g of Cr Irradiated for ~3 mnths 517 kCi activity Steve Elliott, UNM Seminar Series
Reactor Layout 10 reactors Each can hold 8 tons of Ga Kept warm so Ga is liquid Steve Elliott, UNM Seminar Series
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
Proportional Counter Spectrum Steve Elliott, UNM Seminar Series
Results - Solar Rate Each run saw about 6 signal Events. Expect 128 SNU Steve Elliott, UNM Seminar Series
Gran Sasso Italy: Not too far from Rome Steve Elliott, UNM Seminar Series
GNO Layout Steve Elliott, UNM Seminar Series
GALLEX Results Expected 128 SNU Steve Elliott, UNM Seminar Series
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
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
Photomultiplier Tubes Steve Elliott, UNM Seminar Series
SuperKamiokande Characteristics • 50,000 t water • 11,146 20” pmt • 1,885 8” pmt Steve Elliott, UNM Seminar Series
SuperK Data Steve Elliott, UNM Seminar Series
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
SNO’s Location < 100 m/day Steve Elliott, UNM Seminar Series
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
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
An example Event: atmospheric neutrino Steve Elliott, UNM Seminar Series
SNO data Radius of event vertex Angle with Sun Steve Elliott, UNM Seminar Series
Event Energy Steve Elliott, UNM Seminar Series
NC vs. CC Steve Elliott, UNM Seminar Series