Carbon-14 decays into nitrogen-14 with the release of an electron (β−\beta^-β−) and an electron antineutrino (νˉe\bar{\nu}_eνˉe).
State the change of quark character in β−\beta^-β−.
Figure 1 shows the distribution of kinetic energies of β−\beta^-β− particles from the decay of carbon-14.
Explain how Figure 1 supports the existence of the antineutrino.
The existence of the antineutrino is also confirmed by interactions with nuclei. In one such interaction:
νˉe+p→e++X \bar{\nu}_e + \text{p} \rightarrow \text{e}^+ + X νˉe+p→e++XIdentify particle XXX.
The electron released in the decay is annihilated when it encounters a positron in surrounding matter. A pair of gamma photons of equal energy is then produced.
During an experiment, three gamma photons are detected:
- ϕ1\phi_1ϕ1 with energy 4.5×10−14 J4.5 \times 10^{-14}\text{ J}4.5×10−14 J
- ϕ2\phi_2ϕ2 with energy 8.0×10−14 J8.0 \times 10^{-14}\text{ J}8.0×10−14 J
- ϕ3\phi_3ϕ3 with energy 8.3×10−14 J8.3 \times 10^{-14}\text{ J}8.3×10−14 J
Deduce which of the three gamma photons could have been produced by this electron-positron annihilation.