Beta Spectroscopy

Nuclear ß-decay
We define the Q value to be the difference between the initial and final nuclear mass energies.
For the following case
the Q value would be:
n
Q
→
p
+
e
−
+ ν
2
( m − m − m − m ) c
=
n p
−
e
0
Let us consider the three cases of ß-decay in a nucleus:
β − - decay :
A
z
X
→
A
z+
1
X'
+ e
−
+
υ
Q
−
β
=
[m
N
(
A
z
X) − m
N
(
A
z+
1
X') − m
e
]c
2
In the above case m N
indicates nuclear masses. In order to use the tabulated atomic masses
we have to convert these using the following
m(
A
X)c
2
= m
N
(
A
X)c
2
+ Z
m c
e
2
−
Z
∑
i=
1
B
i
B i
is the binding energy of the i th electron. Replacing in the formula above we obtain:
Q
−
β
= [m(
A
X) − m(
A
X') ]c
2
The Q value represents the energy shared by the electron and the neutrino
Q = T + E
−
β
e
υ