Gollnick problem... can't solve

[Zorro1]

I know the solution to this is probably simple but on problem set 9 of ch. 2 in Gollnick's Basic rad pro tech. it asks: Calculate the average energy of the negatron and neutrino emitted in the beta decay of 90Y..... the answers are (Beta = 0.758 MeV, neutrino = 1.52MeV)    how did they come to this?

[Rennhack]

Good question, thank you for asking.

Chapter 2, Page 44:

In beta decay, we often call this energy the endpoint energy or E_maximum. On the average, betas carry about 1/3 of the endpoint energy.

2.278 * 1/3 = 0.758


Chapter 2, Page 46:

Remember that the betas emitted have a range of energies up to the value of the decay energy, E_maximum. On the average, they carry 1/3 E_max and the neutrinos 2/3 E_max.

2.278 * 2/3 = 1.52