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Neutrino Physics - Lecture 6 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068, elliotts@lanl.gov

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Spring 2007Steve Elliott, UNM Seminar Series2 Lecture 6 Outline Reactor Neutrinos (Many slides from Bob Mckeown) The neutrinos Past experiments What we know and what we want to learn

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Spring 2007Steve Elliott, UNM Seminar Series3 Reactor Experiments CHOOZ, Palo Verde Double CHOOZ, Daya Bay Texono –Neutrino magnetic moment –Coherent scattering

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Spring 2007Steve Elliott, UNM Seminar Series4 Distance (m) P( e e ) Dominant 12 Oscillation Subdominant 13 Oscillation Anti- e Disappearance

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Spring 2007Steve Elliott, UNM Seminar Series5 13 90, 95, 99% CL hep-ph/0309130 m 23 2 from SK atmospheric Chooz Solar

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Spring 2007Steve Elliott, UNM Seminar Series6 Neutrino Oscillation Studies with Nuclear Reactors e from n-rich fission products detection via inverse beta decay ( e +p e + +n) Measure flux and energy spectrum Improve detectors, reduce background Variety of distances L= 10m-250km

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Spring 2007Steve Elliott, UNM Seminar Series7 Detection Signal Coincidence signal: detect Prompt: e + annihilation E E prompt +E n +0.8 MeV Delayed: n capture 180 s capture time p + e 511keV 2.2 MeV d n

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Spring 2007Steve Elliott, UNM Seminar Series8

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Spring 2007Steve Elliott, UNM Seminar Series9 KamLAND uses the entire Japanese nuclear power industry as a longbaseline source Kashiwazaki Takahama Ohi

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Spring 2007Steve Elliott, UNM Seminar Series10

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Spring 2007Steve Elliott, UNM Seminar Series11 Solar : m 2 = 5.5x10 -5 eV 2 sin 2 2 = 0.833 G.Fogli et al., PR D66, 010001-406, (2002) Ratio of Measured and Expected e Flux from Reactor Neutrino Experiments

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Spring 2007Steve Elliott, UNM Seminar Series12 Measurement of Energy Spectrum

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Spring 2007Steve Elliott, UNM Seminar Series13 KamLAND best fit : m 2 = 7.9 x 10 -5 eV 2 tan 2 = 0.45 KamLAND fixes mass Solar fixes angle

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Spring 2007Steve Elliott, UNM Seminar Series14 Geoneutrinos Nature 436, 499 Two estimates of total power dissipated by Earth 44.2 ± 1 TW 30 ± 1 TW 19 TW is estimated to be due to radiogenic sources, 84% due to Th/U decay, some mantle studies imply it might be larger.

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Spring 2007Steve Elliott, UNM Seminar Series15 New Reactor Proposals Braidwood, Il Daya Bay, China Chooz, France ~1.5 km baseline Deeper/bigger Near/Far KASKA

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Spring 2007Steve Elliott, UNM Seminar Series16 Detector Design Studies horizontal cylinder spherical

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Spring 2007Steve Elliott, UNM Seminar Series17 Daya Bay Each detector: Inner zone 20 tons Gd-doped LS Defined by acylic Outer zone just LS Outermost zone just mineral oil 224 pmts Sin 2 13 ~ 0.008 Constr. 2007 Data start 2009

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Spring 2007Steve Elliott, UNM Seminar Series18 Double Chooz Sin 2 13 ~ 0.022- 0.030 Data 2008 Daya Bay and Double Chooz have similar concepts for LS

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Spring 2007Steve Elliott, UNM Seminar Series19 New Properties Unexpected new neutrino properties –CPT invariance violation –Equivalence principle violation –Lorentz violation Would appear as oscillation effects but with a departure from the classic oscillation wavelength energy dependence Mass varying neutrinos –Dark energy scale {2 meV} is similar to scale of neutrino mass splitting {(9 meV) 2 } –Might be observable in oscillation, experiments

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Spring 2007Steve Elliott, UNM Seminar Series20 Magnetic Moments Do neutrinos have magnetic moments? Dirac neutrinos can posses static moments Majorana neutrinos can possess transition moments SM predicts very small value: 3x10 -19 (m /eV) B Present limits: <9x10 -11 B Measurements hard because the possible EM and known WI contributions are similar in magnitude. Astrophysical constraints in addition to reactor/accelerator limits. Beta beams and tritium sources have also been proposed.

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Spring 2007Steve Elliott, UNM Seminar Series21 Electron elastic scattering experiments Neutrino elastic scattering cross sections scale as E 2, whereas the B interaction are mostly energy independent. Thus the EM cross section may dominate at low energies. Reactor neutrino experiments are the best to date. Most recent: TEXONO expt. in Taiwan PR D75 (2007) 012001

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Spring 2007Steve Elliott, UNM Seminar Series22 Coherent nuclear scattering experiments 1 MeV neutrino with 10 -10 B scattered on a N=Z spin 0 nucleus has Spin contributions enhance SM cross section. For N≠Z, isospin dependent terms contribute. High A nuclei have low recoil energies. Like ES, largest ratio is for low recoil energy J.Phys.Conf.Ser. 39 (2006) 266

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