In the decay 64Cu → 64Ni + e+ + v, the maximum kinetic energy carried by the positron is found to be 0.650 MeV.
(a) What is the energy of the neutrino which was emitted together with a positron of kinetic energy 0.150 MeV?
(b) What is the momentum of this neutrino in kg m s−1?
Use the formula applicable to a photon.
Maximum kinetic energy of the positron, K = 0.650 MeV
(a) Neutrino and positron are emitted simultaneously.
∴ Energy of neutrino = 0.650 − Kinetic energy of the given positron
= 0.650 − 0.150
= 0.5 MeV = 500 keV
(b) Momentum of the neutrino, `P = E/c`
Here, E = Energy of neutrino
c = Speed of light
⇒ `P = (500 xx 1.6 xx 10^-19)/(3 xx 10^8) xx 10^3`
= `2.67 xx 10^-22 "Kgms"^-1`