Neutrinos are chargeless, nearly massless particles Most abundant particle in the Universe Interact with matter via weak nuclear force

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1 By Wndi Wamlr

2 Nutrinos ar charglss, narly masslss articls Most abundant articl in th Univrs Intract with mattr via wak nuclar forc Narly transarnt to mattr Only known ty of articl that can sca from th sun s cor without intracting Hyothsizd in 1930 Bta dcay

3 Th sun, and all othr stars, shin du to nuclar fusion ractions haning at th cor d d 3 H 4 H 7 B 7 Li 8 B 8 B

4 Raymond Davis Jr., Homstak Min in SD, 1964 Basd on rvrs bta dcay of chlorin atoms 37 Cl 470 mtric tons of rchlorothyln solution ~10 30 atoms Cl Saw atom dcays onc vry fw days About half of what th solar modl rdictd 37 Ar Cl has too high of an nrgy thrshold for nutrinos in sun s rimary roton-roton ractions Dtcts only nutrinos with highr nrgy; thos from B and B dcays

5 Sudbury Nutrino Obsrvatory Dtcts all thr tys of nutrinos using havy watr (D 2 0) can saratly obsrv lctron nutrinos and all tys of nutrinos Masurs flux, nrgy, and dirction of lctron nutrinos roducd by sun From flux and sha of th nrgy sctrums thy can dtrmin how strongly th flavours mix

6 2 Chargd currnt raction Whn lctron nutrino aroachs dutrium, W is xchangd lctron is jctd at th sd of light (which is fastr than th sd of light in watr) Givs off shockwav of light calld Chrnkov Radiation Dtctd by hotomultilir tubs (PMT) Pattrns can b rlatd to nrgis of th nutrinos and thir angular distribution Standard solar modl rdicts ~ 30 chargd currnt vnts/day d

7 2 Nutral Currnt Raction Z boson is xchangd Whn nutron caturd by anothr nuclus, gamma rays ar mittd and can b dtctd Equally snsitiv to all tys of nutrinos 3-H roortional countrs hung in grid within D 2 O 35-Cl can b addd to NaCl High absortion cross-sction sction for thrmo nutrons Standard solar modl rdicts ~30 nutral currnt vnts/day d n

8 2 Elctron Scattring Not uniqu to havy watr Snsitiv to all nutrinos, but lctron nutrinos ar mor likly by a factor of 6 Littl sctral information gaind Good dirctional information Standard solar modl rdicts ~ 3 vnts/day

9 Problm - Flux of lctron nutrinos is still too low Total flux of nutrinos agrs with standard solar modl Solutions Solar solution roblm with solar modl Much invstigation has found that our currnt modl is vry accurat Nutrino solution roblm with our thory of nutrinos

10 Thr wr thr solutions considrd: 1. Irrgular nutrino mission sctra or othr bta dcay odditis 2. Nutrino oscillations 3. Irrgular nutrino intractions with dtctors 1 and 3 hav bn tstd xtnsivly in labs 2 involvs nutrino travl across astronomical distancs Suortd by rorts that anomalis occur during travl of trrstrial distancs

11 Surosition a mixtur of stats Bhav as th K 0 mson - roducd in a wak-intraction ignstat (flavor), but travl in a mass ignstat intract with our dtctors as a mixtur of two or mor flavors Good data fit: 100% lctron-nutrino nutrino lavs sun, and nds u a mix of ~ 40% lctron-nutrino nutrino and ~60% som othr nutrinos Nutrinos occuy corrsonding lac in lton familis as to K 0 and B 0 constitunt quarks in quark familis Procss can only occur if nutrinos hav mass Nutrinos in Standard modl Elctron nutrino Elctron antinutrino Muon nutrino Muon antinutrino Tau nutrino Tau antinutrino Mass < 2.5 V < 2.5 V < 170 kv < 170 kv < 18 MV < 18 MV

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13 SNO homag htt:// Talk Origins htt:// solar.html John Bahcall homag htt:// Bahcall,, John. How Uncrtain ar Solar Nutrino Prdictions? Physics Lttrs B. vol , Bahcall,, John. Whr do w stand with solar nutrino oscillations? Physical Rviw D. vol. 58, 1998

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