Tau Neutrino Physics Introductionnt – the third neutrinoThe Number of Neutrinos big-bang nucleosynthesisThe Number of Neutrinos collider experiments properties existence properties existence – DONUT concept properties existence – DONUT detectorsSlide 8 properties existence – DONUT events/background propertiesSlide 11nt properties direct mass measurementsnt properties direct mass measurementsnt properties direct mass measurementsnt properties direct mass measurements + cosmological boundsnt properties lepton sector mixingnt properties oscillation probabilitynt properties oscillation phenomenan oscillations allowed regionsn oscillations atmospheric neutrinosatmospheric neutrinos ratio of nm events to ne eventsatmospheric neutrinos angular distributionsatmospheric neutrinos angular distributions with n oscillationsatmospheric neutrinos energy dependence - n oscillationsnt properties mass difference – neutrino oscillationsatmospheric neutrinos high energy events – upward muonsatmospheric neutrinos MACRO event typesatmospheric neutrinos MACRO high energy eventsatmospheric neutrinos MACRO evidence for oscillationsatmospheric neutrinos agreement between measurements and experimentsatmospheric neutrinos oscillation to sterile or tau neutrino??Slide 32Slide 33nt future speculations - supernovaeSlide 35Slide 36nt the ultra high energy neutrino universent the ultra high energy neutrino universeSlide 39nt future speculations – cosmic nt’sSlide 41Slide 42Accelerators long baseline nm – nt oscillationsSlide 44Accelerators neutrino factory – neutrinos from muon colliderSlide 46ConclusionsTau Neutrino PhysicsIntroductionBarry Barish18 September 2000 – the third neutrinoThe Number of Neutrinosbig-bang nucleosynthesisD, 3He, 4He and 7Li primordial abundances• abundances range over nine orders of magnitude • Y < 0.25 from number of neutrons when nucleosynthesis began (Y is the 4He fraction)• Yobserved = 0.2380.0020.005• presence of additional neutrinos would at the time of nucleosynthesis increases the energy density of the Universe and hence the expansion rate, leading to larger Y.• YBBN= 0.012-0.014 N 1.7  N  4.3The Number of Neutrinoscollider experiments• most precise measurements come from Z  e + e• invisible partial width, inv, determined by subtracting measured visible partial widths (Z decays to quarks and charged leptons) from the Z width • invisible width assumed to be due to N•Standard Model value (  l)SM = 1.991  0.001 (using ratio reduces model dependence)SMllinvNN = 2.984 0.008 propertiesexistence• Existence was indirectly established from decay data combined with reaction data (Feldman 81).• DIRECT EVIDENCE WAS PRESENTED THIS SUMMER FROM FNAL DONUT EXPERIMENTObserve the and its decays from  charged current interactions propertiesexistence – DONUT concept•calculated number of interactions = 1100 ( , e , )• total protons on target = 3.6 1017• data taken from April to September 1997 propertiesexistence – DONUT detectorsSpectrometerEmulsion-Vertex Detectors propertiesexistence – DONUT detectors• 6.6 106 triggers yield 203 candidate events propertiesexistence – DONUT events/background4 events observed4.1  1.4 expected0.41± 0.15 background properties• expect    for Majorana or chiral massless Dirac neutrinos• extending SU(2)xU(1) for massive neutrinos,  BFmmeG1921020.328/3where m is in eV and B  eh/2me Bohr magnetons.• using upper bound m 18 eV   < 0.6 10-11 • Experimental Bound < 5.4 10-7  from e  e (BEBC)magnetic momentJ = ½• J = 3/2 ruled out by establishing that the is not in a pure H  -1 helicity state in  properties< 5.2 10-17 e cm from (Z  ee) at LEP charge< 2 10-14 from Luminosity of Red Giants (Raffelt)lifetimeelectric dipole moment> 2.8 1015 sec/eV Astrophysics (Bludman) for m < 50 eVproperties direct mass measurements• direct bounds come from reconstruction of  multi-hadronic decays LEP (Aleph) from 2939 events   2 +  + < 22.3 MeV/c2 and 52 events   3 + 2 + () +  < 21.5 MeV/c2combined limit < 18.2 MeV/c2 propertiesdirect mass measurements• methodtwo body decayph Ehphptau rest frame – hadronic energyhmmh2 +m2) / 2mlaboratory frameEh =  (Eh* +  ph* cos)interval bounded for different mEhmax,min = (Eh*   ph*)two sample events  3 + 2 + () +  propertiesdirect mass measurements events & contours 0 MeV/c2 and 23 MeV/c2Log-likelihood fit vs m propertiesdirect mass measurements + cosmological bounds• bounds on m from cosmology• combined with non observation of lepton number violating decay and direct mass limitsUnstable  propertieslepton sector mixing propertiesoscillation probability propertiesoscillation phenomena oscillationsallowed regions oscillationsatmospheric neutrinosPath length from ~20km to 12700 kmatmospheric neutrinosratio of  events to e eventsratio-of-ratios (reduces systematics): • R = (e)obs / (e)predhint #1 ratio lower than expectedatmospheric neutrinosangular distributionsSuperkamiokande Hint #2 anisotropy up/down and distortion of the angular distribution of the up-going eventsatmospheric neutrinosangular distributions with  oscillationsatmospheric neutrinosenergy dependence -  oscillationsHint #3 anomalies have been found in a consistent way for all energiesDetectors can detect internal of external events produced in the rock below the detector – 100 MeV to 1 TeV propertiesmass difference – neutrino oscillationsSuperKamiokandeatmospheric neutrinoshigh energy events – upward muonsMACRO Detectoratmospheric neutrinosMACRO event typesDetector mass ~ 5.3 ktonEvent Rate:(1) up throughgoing m (ToF) ~160 /y(2) internal upgoing m (ToF) ~ 50/y(3) internal downgoing m (no ToF) ~ 35/y(4) upgoing