Question

Design a mass spectrometer to distinguish between isotopes of Carbon (C112 and C14).

The first stage is an ion gun in which carbon is blasted into a gas form and ionized to a +e charge. An electric field ejects a collimated beam of mixed C12 and C14 isotopes into a velocity filter with average energy 500eV.

In the design, there should be access to a 1T magnetic field you can use for both your velocity filter and detector regions. In the velocity filter section, you will balance electric and magnetic forces. As the velocity filter is not influenced by mass, all charged ions exiting the filter will have the same velocity. In the detector region there is only the magnetic field, so charged ions travel in a half circle to collide with a detector.

Your instrument is designed so that the C12 ions strike the detector 50 cm below the entrance to the detector region. Using this information to determine the following:

1. What is the mass of C12 and C14 in kg?

2. What speed are the C12 and C14 ions traveling?

3. Where should you place the C14 detector?

4. The velocity filter section is made of two parallel plates seperated by 1 cm. What Voltage should be applied across the plates?

Answer 1