Beta Particles Essay Research Paper Beta ParticlesAimI

Beta Particles Essay, Research Paper

Beta Particles

Aim:

I will investigate how the field strength varies the deflection of Beta Particles.

Preliminary Work

I started my preliminary work because, when I started my measurements using 2 coils used in experiments to deflect electrons from and electron gun. While testing for the deflection of beta particles, I found that beta radiation was scattered in a very large cone, I can not get any readings with amount of beta radiation scattering.

So I would have to construct some type of shielding for this investigation, this is so I can measure the deflection more easily. The angle at which the beta particles are being scattered is 48o.

Deciding on the Type of Shielding

I will test for the best shielding. The best properties of the shield will be; it can be malleable to form different shapes and can be punctured, can stop radiation at a small thickness.

Diagram

Equipment

Strontium 90 beta source

GM tube + counter

Different thickness of different metals

Clamps, bosses and clamp stand to hold the source and the material being tested.

Method

1. Set-up equipment as in the diagram

2. Record the thickness and the material being used.

3. Record 5 readings of the radiation count, and record them in a table

4. Replace material being tested with different material or a different sized material.

5. Repeat steps 2 to 4 as required.

Results

The background radiation reading is 2, 4, 6, 4, 5, 2. The average count is 3.8 (1dp).

Conclusion

This shows that aluminium stops radiation at 3.5 mm, this would be difficult to use because, this thickness of Aluminium is not malleable and the aluminium is not soft enough to puncture. Lead can stop radiation at very thin thickness , also lead is very malleable and is soft enough to puncture. I will use Lead shield at 0.6mm thick, since it is the most abundant thickness available and it is the easiest to form to any shape I want.

Deciding how the shielding can be used.

I want to have a tight beam of beta particles in this investigation, so I will use my knowledge on what would be the best way to shield the source.

An unshielded source

The source is unshielded and has beta particles spreading out. Angle Theta is the angle which the beta particles are scattered through. The path of the beta particles is not a straight line, but a curve because the beta particle are deflected by the moles in the air. The points A B are the furthest points where beta ration is detected.

Using a plate shielding

The beta particles have a smaller angle, that they are being scattered through. Also if the shield isn t wide enough the beta particles that travelled either side of the shielding could cause problems. For example, when measuring the deflection of the beta particles in the electric field, the beta particles that passes outside of the shield will interfere with detecting the deflection of the Beta.

Using a cylindrical shielding

The cylindrical shielding produces a smaller angle which the beta particles are being scattered through than the source. But this is too wide to for I want to use. So I will need a compromise of the plate shielding and the cylindrical shielding.

Using Compressive Shielding

This shielding produces the smallest angle for scattering because the cylinder stops the beta particles that spread out to the side, the plate stops all the beta particles that don t pass through the hole.

The smaller the hole in the plate shield will affect the counts, because the smaller the hole then greater the number of beta particles are absorbed by the shielding. The size of the cylinder does not matter as long it has a diameter greater than sources width, because the beta particles will do the same thing as in fig 3.

Making the shielding

To make the shielding, I must be accurate in making the hole in the plate, I will do this by using a tool designed to make regular indentations. This tool can make holes from 5mm wide to 9mm with intervals of 1mm. In making the cylindrical shielding, it doesn t have to be a cylinder to produce the same desired affect. I will use a round metal bar with which to roll the lead shielding. The both parts of the shield will be stuck together with tape, because if I piece become damaged or deformed, it can replaced easily.

Measuring the Angle at Which Beta Particles Are Scattered Through With different Diameters of punctures

Diagram

Equipment

Strontium 90 beta source

GM Tube

Lead Shielding (43.6mm long)

Counter

Method

Note: To make sure that the GM tube, the puncture and the source is in alignment, draw a straight-line with a rule on the table. Then use a set square to get the perpendicular vertical line. Mark a set distance, this mark will be placed in the centre of the source, GM and the punter along the table. (Careful with the source, approximate the centre, see safety notes).

1. Set-up the equipment as the diagram, measure the distance (20cm) with an accurate rule, stating with plate shield have in a puncture of 5mm to start with.

2. Take 10 readi

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