The Solar Neutrino Problem
For more than twenty years, the Homestake Solar Neutrino Experiment in the Homestake Gold Mine in South Dakota has been attempting to measure neutrino fluxes from space; in particular, this experiment has been gathering information on solar neutrino fluxes. The results of this experiment have been checked against predictions made by standard solar models and it has been discovered that only one-third of the expected solar neutrino flux has been detected. This "Where are the missing neutrinos?" question is known as the Solar Neutrino Problem.
And it is not just the Homestake experiment that is detecting a shortage of neutrinos. Several other experiments, including Kamiokande II, GALLEX, and SAGE, have noticed a definite neutrino shortfall.
And it is not just the Homestake experiment that is detecting a shortage of neutrinos. Several other experiments, including Kamiokande II, GALLEX, and SAGE, have noticed a definite neutrino shortfall.
What Is a Neutrino
What Is a Neutrino ? Neutrinos are subatomic particles produced during nuclear fission and fusion processes. Like electrons (and muons and tauons), neutrinos are classified as leptons. There are three "flavours" of neutrinos: electron neutrinos, muon neutrinos, and tauon neutrinos. At this time it is unknown whether neutrinos have either mass or magnetic moments but recent observations of Supernova 1987A have set an upper limit on any neutrino magnetic moments at less than about 10^(-13) Bohr magnetons. If neutrinos do have a magnetic moment, then they will either be "left-handed" or "right-handed" in orientation.
How Does the Sun Produce Neutrinos? The Sun produces energy by fusing hydrogen to helium. This may be accomplished in a number of ways but in the Sun, a process known as the proton-proton chain is thought to be primarily responsible for energy generation.
H + H --> D + positron + neutrino
H + H + electron --> D + neutrino
D + H --> He3 + gamma ray
He3 + He3 --> H + H + He4
He3 + He4 --> Be7 + gamma ray
Be7 + positron --> Li7 + neutrino
Li7 + H --> He4 + He4
Be7 + H --> B8 + gamma ray
B8 --> Be8* + positron + neutrino
Be8* --> He4 + He4
H is hydrogen, D is deuterium (heavy hydrogen), He is helium, Li is lithium, Be is beryllium, and B is boron. Numbers indicate different isotopes. The Homestake experiment detects only the highest energy neutrinos produced by the Sun, the neutrinos produced by the beryllium/boron reactions.
How Does the Sun Produce Neutrinos? The Sun produces energy by fusing hydrogen to helium. This may be accomplished in a number of ways but in the Sun, a process known as the proton-proton chain is thought to be primarily responsible for energy generation.
H + H --> D + positron + neutrino
H + H + electron --> D + neutrino
D + H --> He3 + gamma ray
He3 + He3 --> H + H + He4
He3 + He4 --> Be7 + gamma ray
Be7 + positron --> Li7 + neutrino
Li7 + H --> He4 + He4
Be7 + H --> B8 + gamma ray
B8 --> Be8* + positron + neutrino
Be8* --> He4 + He4
H is hydrogen, D is deuterium (heavy hydrogen), He is helium, Li is lithium, Be is beryllium, and B is boron. Numbers indicate different isotopes. The Homestake experiment detects only the highest energy neutrinos produced by the Sun, the neutrinos produced by the beryllium/boron reactions.
