Why Does Co-60 Decay to an Excited State of Ni-60 and Emit Two Photons?

[Raz91]

Hello,

my question is :
C60 ---> Ni60+e^-+anti-neutrino

why does Co60 decay to an excited state of Ni60 and not directly to its ground state?
and why does the Ni emite two photons (first transition from the second excited state to the first excited state and from the first excited state to the ground state) and not directly to its ground state?

thank you! :)

 

[Vanadium 50]

Do you know what "selection rules" are?

 

[Raz91]

yeah i know

i know that ΔJ=±1,0

Just don't understand how does it applied here ...

 

[Raz91]

as i saw - Co60 has J=5 and Ni J=4
so why Ni can't be with J=5 same as Co ?
why the transition of ΔJ=-1 is taking place and not ΔJ=0?

thank u :)