Kinetic energy of an electron on the β spectrum?

[richphys]

Homework Statement

A ¹⁹¹Os nucleus decays via β- emission to an excited state of ¹⁹¹Ir at 171 keV. What is the maximum kinetic energy of the electron on the β spectrum?
a) 0.134 MeV
b) 0.143 MeV
c) 0.171 MeV
d) 1.859 MeV

Homework Equations

¹⁹¹ Os = 190.960928u
¹⁹¹ Ir = 190.960591u

(190.960928u - 190.960591u) * 931.5MeV/u = 0.3139 MeV

0.3139 MeV - 0.171 MeV = 0.143 MeV

The Attempt at a Solution

[/B]
I am unsure if my answer of 0.143 MeV is correct. In my notes it says the maximum kinetic energy is equal to the Q value of the reaction, so I wokred out the Q value above then subtracted the "excited state" value.

 

[mfb]

That is right.

 

[Turkishking]

Indeed