Although the neutron-capture cross section curve is generally proportional to 1/v, where v is the velocity of the incident neutrons, it has several pronounced peaks. These peaks are an indication of
A) resonances with nuclear energy levels.
B) characteristic $\gamma$ rays from the nucleus.
C) barrier penetration.
D) $\alpha$ particle emission.
E) characteristic X rays.

Question

Although the neutron-capture cross section curve is generally proportional to 1/v, where v is the velocity of the incident neutrons, it has several pronounced peaks. These peaks are an indication of
A) resonances with nuclear energy levels. 
B) characteristic $\gamma$ rays from the nucleus. 
C) barrier penetration. 
D) $\alpha$ particle emission. 
E) characteristic X rays.

Quizplus · Accepted Answer

The pronounced peaks in the neutron-capture cross section curve are an indication of resonances with nuclear energy levels. When the incident neutron has an energy that matches the energy of an excited state in the nucleus, the neutron can be captured with a much higher probability, leading to a peak in the cross section curve. These resonances are a result of the wave nature of neutrons and the interaction of the neutron with the nuclear structure.

Although the Neutron-Capture Cross Section Curve Is Generally Proportional to 1/v