PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
In a liquid scintillation detector, electron-type antineutrinos originating from a reactor are observed through the following two-step sequence:
Step 1 (inverse beta interaction inside the detector):
νˉe+p⟶n+X
Step 2 (radioactive decay of the newly formed neutron):
n⟶p+Y+Z
In each reaction, only the particles explicitly written (including the unknowns X, Y, and Z) are produced. The atomic electron cloud is not shown.
(a) Identify particle X by giving its name and symbol so that Step 1 is balanced with respect to charge and lepton number.
(b) Show explicitly that total lepton number is conserved in Step 1 when your answer from part (a) is included.
(c) Determine the identities (name and symbol) of particles Y and Z in Step 2, writing a balanced equation.
(d) Considering the complete two-step process, calculate the net change in the total lepton number and in the electron-flavor lepton number from the initial state (before Step 1) to the final state (after Step 2).