Work, Power and Energy
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Question : 30
Total: 30
Consider the decay of a free neutron at rest : n → p + e –
Show that the two-body decay of this type must necessarily give an electron of fixed energy and, therefore, cannot account for the observed continuous energy distribution to the β-decay of a neutron of a nucleus as shown in the figure.
Show that the two-body decay of this type must necessarily give an electron of fixed energy and, therefore, cannot account for the observed continuous energy distribution to the β-decay of a neutron of a nucleus as shown in the figure.
Solution:
In the decay process, n → p + e
energy of electron is equal to( Δ m ) c 2
where Δm = mass defect
= mass of neutron – mass of proton and electron;
which is fixed. Therefore, two body decay of this type cannot explain the observed continuousenergy distribution in the b-decay of a neutron or a nucleus.
Note : The simple result of this exercise was one among the several arguments advanced by W. Pauli to predict the existence of a third particle in the decay products of β-decay. The particle is known as neutrino. We now know that it is a particle of intrinsic spin
e – , p n n → p + e – + v
energy of electron is equal to
where Δm = mass defect
= mass of neutron – mass of proton and electron;
which is fixed. Therefore, two body decay of this type cannot explain the observed continuousenergy distribution in the b-decay of a neutron or a nucleus.
Note : The simple result of this exercise was one among the several arguments advanced by W. Pauli to predict the existence of a third particle in the decay products of β-decay. The particle is known as neutrino. We now know that it is a particle of intrinsic spin
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