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neutrinos - Neutrinos(Kulner Ch 9 Bennett et al Ch...

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Unformatted text preview: Neutrinos (Kulner, Ch. 9, Bennett et al. Ch. 14,Hester elal. Ch. 14) AST 203 (Spring 2011) The Standard Model NUGiUS PROTON GUARK k Eindmn Naulmn Pmlon (Nazis) Alt ORDINARY MMTER BELONG: m TH|5 “our. Electron v o a O ESE: EIecllic charger! Eladric charge 0 Electric char e + 2/3 Elslrlc char 5 Responsiblelueieclncily Rune inlerucls norm vs Piulunssiiuve n undcliemicul reunions wilh ermalter 2 Upkqlmrks Nemmi ‘l Dan/“quark Neuimz I r0: TH! MUST Muon Muon neutrino Charm (c) Strange (s) PARY, "4:5: PARHCLES EXISTED A heavier 0 Created with n o A Heavier IN THE DAILY relative mucus when some relative MOMENTS "TE" oi lhe Electron particles decay of the Dawn THE BIG BANG. Tau Tau neutrino Bottom (b) Heavier o ‘ Heavier 0 still slill AN'I'IMATTER Each panicle also has an unlimanar counlarpan ... son if a mirror imuga. All ordinary matter is made up of two fundamental types of elementary particles: quarks and leptons. The standard model is very successful in describing matter. AST 203 (Spring 2011) P-P (Kutner 9.3) 4 1H —> 1 4He releases 2 neutrinos. mass difference, Am 2 0.03 mp corresponds to the binding energy of Ofv Ofv the helium nucleus. R f K ? Neutrinos interact weakly with matter —free stream out of the Sun. yfi fiy We can: K ;/3 Predict the # of neutrinos we expect to be produced in the Sun 0 o Create detectors in hopes of observing them 1 a g _ I V Nutrino If we see the amount we predict, O P """" ““ then things are good! wkipedia) AST 203 (Spring 2011) Solar Neutrinos (Bennett et al. Ch. 14) Neutrinos are hard to detect—they pass right through the Sun, why can see stop them? ~1010 neutrinos pass through every cm2 of your body per sec. To stop the average neutrino, you would need 1 lightyear of lead! This is a statement of the mean free path Large detector —> hope for a few chance encounters with solar neutrinos. Usually, these detectors a placed in deep mines to shield them from background radiation. AST 203 (Spring 2011) Solar Neutrinos All of the neutrino producing reactions in the Sun 0 U p++p+—>3H+e++ve 4799 77 A: 0T2?) A, p++e’+p+—>3H+ve 1 2H (awed!wa 5% 0, p+—>3He+ y *3He+p+ —> 4H6 +e++ve l 15,08 % 3He’AHo—)7Be+ y 732 i 993% j 0,1 % ’Be+e’—>7Li+ve 7136+er _)sB+ y 84,92 "/0 v l i 3Hot-"‘Hc‘;—)4He"2p+ 7Li+p+—>4He+4He 813—) 8Be"‘+e++ve m l 8]36"‘—>4He+4He —m AST 203 (Spring 2011) Solar Neutrinos Neutrino produced from the 8B decay is of high enough energy that we have a chance to detect it. Davis Experiment was built in the 1960s in the Homestake mine in South Dakota, 1500 m below ground. It contained 400,000 L of dry cleaning fluid (CZCI4). AST 203 (Spring 2011) Solar Neutrinos (Kutner Ch. 9; Hester Ch. 14, Bennett et al. Ch. 14) Detector filled with chlorine-37. Looks for: 37C1+ 1/ —> 37Ar + 6— Every few weeks, the tank is drained and the Argon inside is measured. In 2 days, about 1022 neutrinos will pass through the tank and measurements showed than only one interacts. After many decades of measuring, the experiment found only 1/3rd of the expected neutrinos—solar neutrino problem. AST 203 (Spring 2011) Solar Neutrinos Other reactions roduce neutrinos with ‘ S K‘ SNO gifferent energies I Gallium IChlorlne 101: |.....—.| . ,. .nu. 10” Bahcall—Pinsonneault 2004 a Detectors with gallium 10” instead of chlorine are 10' sensitive to neutrinos from a wider range of reactions. 10' 10” 10° Neutrino Flux 105 10‘ 105 These experiments still measured only 1/3rd of the expected # 10e ‘l to 0.] Neutrino Energy (MeV) (John Bachall) AST 203 (Spring 2011) Solar Neutrinos neutrinos come in 3 different flavors. The p-p chain makes only electron neutrinos, but perhaps, somehow, the different neutrinos can change flavors. m "nus GKDUP. PROI'ON Nutth Plohan (Nazis) E7 Down (11) ‘l o l O Emepc'dcggggfijv; 2/3 Electric clargne *l /3 {F Proton: ave 1 er er 2 Up quarks, Neurons l l Dom quark, Neutrons 2 ' FOR THE MOST Muon Muun neutrino Charm (c) Strange (5) ns ea 0 some Ing mm PAImcL 15m: A hem-2r 0 Created wnh a A hsawev A hammer O I 2 a mans when some 'E'GWS relative of the Eleclron purllclea decoy 0* the UP of live Dawn being wrong with our 6;. T T T w B (h) _ au au neutrino up t ottnm understanding of the Sun, 0 v Q slle perhaps we didn't Ammmmm... understand neutrinos very “WWW”?- well. AST 203 (Spring 2011) Solar Neutrinos Sudbury Neutrino Observatory ~ uses 1,000 tons of heavy water in a 12 m sphere surrounded by photomultiplier tubes. SNO is also sensitive to all types of neutrinos. Found some of the electron neutrinos produced in the Sun changed into other types of neutrinos along the way. (PBS) Theoretical physics: neutrinos must has mass. AST 203 (Spring 2011) ...
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