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The solar neutrino problem davis and collaborators

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The solar neutrino problemDavis and collaborators found that solar neutrinos created one radioactve argonatom in the tank every three daysThis rate corresponds to onto one third of the neutrino fux predicted by theoretcalcalculatonsThe Kamiokande experimentDownloaded by Max Fairbank ([email protected])lOMoARcPSD|1668152
The Kamiokande was designed by Masatoshi Koshiba in JapanA large underground tank containing 3000 tons of water wassurrounded by 1100 light detectorsFrom tme to tme, a neutrino struck an electron of a watermolecule, dislodging it.-The recoil electron produces a fash of light, which was sensedby the detectors-By analysing the fashes, it is possible to determine thedirecton of incidence of the neutrinosThese experiments may only detect high energy neutrinos,originated by reactons that occur only part of the tme near the end of the proton-proton chain.-The vast majority of neutrinos originate at the beginning of the p-p chain, but theyare not detected because of their low energyNew experimentsGALLEX (in Italy) and SAGE in RussiaDetector: several tons of gallium (a liquid metal)Low energy neutrinos convert gallium into a radioactve isotope of germaniumBy countng the radioactve atoms of germanium, the physicists were able tomeasure the low energy neutrinosRESULT: detecton of 50-60% of the expected neutron fuxFinding the missing neutrinosSolar neutrinos can transform spontaneously in fight in their path to Earth toanother type of neutrino-Neutrino oscillatonsSudbury neutrino observatory (SNO), CanadaSNO can detect all three types of neutrinos.RESULT: the sun produces the predicted number neutrinos, however about 2/3 ofthem undergo spontaneous oscillatons and change their type.Suns AtmosphereThree regions:-Photosphere (about 400km thick)-Chromosphere (about 2000km this-Solar corona (it extends millions of km into space)Most of the visible (white) light comes from the photosphereThe solar atmosphere is so hot that the gas is primarily in a plasma state-In this conditon, the solar atmosphere is greatly infuenced by the solar magnetcfelds that thread through it.PhotosphereThe visible surface of the sun-It is not a solid surface but is a gas layerWe can only see about 400km into the photosphereVery, very, thinDownloaded by Max Fairbank ([email protected])lOMoARcPSD|1668152
The sun has no surface-The density of the gas decreases with the distance from the core-It looks like the sun has a “surface” because visible light emanates from this singlethin layerIt has features such as the dark sunspots, bright faculae and granules.Limb darkeningan observer looking at the sun’s limb can see only partway into the relatvely coolphotosphere… hence this region appears orange and diman observer looking at the centre of the sun’s disk can see to the hot, hence thisregion appears yellow and brightWe don’t see the centre of the sun, we only see the top of the photosphere, which iswhy it seems darkerSuns rotatondetected by observing the moton of the sunspots in the photosphere

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Physics, Suns, Found, Max Fairbank

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