Atoms, Nuclei & Radiation (CIE AS Physics)

A nucleus X decays by emitting a β+ particle to form a new nucleus, .

State the number of protons and the number of neutrons in nucleus X.

number of protons = ...............................................................

number of neutrons = ...............................................................

State one similarity between a β⁺ particle and a β^– particle.

State the quark composition of a meson.

A hadron consists of two down quarks and a charm quark.

Determine the charge of the hadron. Show your working.

charge = ..................................... C 

The deflection of α-particles by a thin metal foil is investigated with the arrangement shown in Fig 1.1. 

Fig 1.1

The detector of α-particles, D, is moved around the path labelled WXY.

State the environment the apparatus must be enclosed in and explain why this is required for the experiment.

Explain the readings detected by D and the conclusions that were made about the nature of atoms at points

State what the readings detected by D at position Y conclude about the charge of the nucleus. Explain why.

A beam of α-particles produces a current of 3.5 pA. Calculate the number of α-particles per second passing a point in the beam.

When a nucleus of plutonium-239 absorbs a neutron, the following reaction may take place. 

State the values of a, b, x and y.

State two quantities, other than the proton and neutron number, that are conserved in the fission reaction in part (a).

A Plutonium-239 nucleus has a mean density of 1.3 × 10¹⁷ kg m^–3. 

Show that the radius of a Plutonium-239 nucleus is 9.0 × 10^–15 m.

Plutonium-239 is an α-emitter whilst Uranium-237 is a β-emitter.

The study of beta decay provided early hints to the existence of a yet undiscovered particle. 

Scientists were interested in the energy distribution of the beta particles emitted when a radioactive source decayed. The source has an activity of 120 Bq. 

The energy released by each decaying nucleus was labelled as X and the total energy released each second by the source was measured to be 7.5 × 10^–11 J. 

Sketch a graph to show the energy distribution of the beta particles and indicate X on the diagram. 

Determine the value of X to an appropriate degree of accuracy.

Explain why no beta particles had an energy equal to X. 

Suggest the standard form of the two possible equations that represent this decay and define all the terms used. 

A radioactive nucleus  undergoes a beta−minus decay followed by an alpha decay to form a daughter nucleus .

Write a decay equation for this interaction and hence determine the values of A and Z.

Thorium, decays to an isotope of Radium (Ra) through a series of transformations. The particles emitted in successive transformations are:

Determine the resulting nuclide after these successive transformations. 

Through a combination of successive alpha and beta decays, the isotope of any original nucleus can be formed. 

Explain the simplest sequence of alpha and beta decays required to do this.

A nucleus of Bohrium decays to Mendelevium by a sequence of three alpha particle emissions.

Determine the number of neutrons in a nucleus of .