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Nuclear Radius

Q7.

(a) Scattering experiments are used to investigate the nuclei of gold atoms.

In one experiment, alpha particles, all of the same energy (monoenergetic), are incident on a foil made from a single isotope of gold.

(i) State the main interaction when an alpha particle is scattered by a gold nucleus.

[1 mark]

(ii) The gold foil is replaced with another foil of the same size made from a mixture of isotopes of gold. Nothing else in the experiment is changed.

Explain whether or not the scattering distribution of the monoenergetic alpha particles remains the same.

[1 mark]

(b) Data from alpha-particle scattering experiments using elements other than gold allow scientists to relate the radius R, of a nucleus, to its nucleon number, A.

The graph below shows the relationship from the data obtained from a scattering experiment. The data obtained obeys the relationship R = r0 A1/3

(i) Use information from the graph to show that r0 is about 1.4 × 10–15 m.

[1 mark]

(ii) Show that the radius of a nucleus is about 5 × 10–15 m.

[2 marks]

(c) Calculate the density of a nucleus. State an appropriate unit for your answer.

[3 marks]

(Total 8 marks)