For the β⁻ decay ¹⁹⁸Au → ¹⁹⁸Hg* + β⁻ + ν̄, the excited Hg nucleus lies 1.088 MeV above its ground state. Find the maximum kinetic energy of the electron. Atomic masses: ¹⁹⁸Au = 197.968233 u and ¹⁹⁸Hg = 197.966760 u.
Physics · Nuclear physics
JEE Mains Advanced

Question

For the β⁻ decay ¹⁹⁸Au → ¹⁹⁸Hg* + β⁻ + ν̄, the excited Hg nucleus lies 1.088 MeV above its ground state. Find the maximum kinetic energy of the electron. Atomic masses: ¹⁹⁸Au = 197.968233 u and ¹⁹⁸Hg = 197.966760 u.

Physics · Nuclear physics

G1 Physics · Accepted Answer

Q from atomic mass difference is (197.968233−197.966760)×931.5 MeV. Subtract the 1.088 MeV excitation energy; neglecting tiny recoil gives the maximum electron kinetic energy ≈0.2806 MeV.