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GATE 2023 PH – Question 23

Nuclear and Particle Physics · alpha decay, beta-decay, electromagnetic transitions in nuclei · 1 mark · Multiple choice

A 60Co nucleus emits a β-particle and is converted to 60Ni* with JP= 4+, which in turn decays to the 60Ni ground state with JP= 0+ by emitting two photons in succession, as shown in the figure. Which one of the following statements is CORRECT?

Cobalt beta decay and two successive nickel gamma transitions.
  1. 4+ →2+ is an electric octupole transition
  2. 4+ →2+ is a magnetic quadrupole transition
  3. 2+ →0+ is an electric quadrupole transition
  4. 2+ →0+ is a magnetic quadrupole transition

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Correct answer: (C) 2+ →0+ is an electric quadrupole transition

Explanation

A 2 to 0 transition requires multipole order 2. Equal parity selects electric quadrupole E2, excluding magnetic quadrupole.