Hello, let me introduce my experimental Gamma spectroscopy shield that I have build in order to lower the background radiation. It is just a concept but it seems to work fine.
For the manufacturing I've used the following materials:
- an aluminium tube (205mm o.d. x h.135mm) closed from one side by an aluminium flange.
- about 40kg of lead pellets 0.8mm o.d.
- one plastic bottle (80mm o.d.)
I've poured the lead inside the aluminium tube to form an flat and uniform layer 30mm thick. Then I've cut the plastic bottle and I placed it inside the aluminium tube, resting on the bottome lead layer. At this point I've poured the remaining lead pellets filling the hollow space up to the top edge of the aluminium tube. The surronding lead volume is more than 50mm and the shielding is effective.
With my GS-2812 I have a background reading of about 150CPS that reduces to 25CPS inside the shielding.
Since the prototype seems to work fine, I'm thinking to improve it as follow:
- the probe will be inserted from below and will enter the shielding at least for the lenght of the scintillation crystal
- different layer of shielding materials other then lead will be added in order to reduce secondary radiations (bremsstrahlung) due to the strong deceleration of the beta particles hitting the lead of the shield. According to some articles about shielding techniques, layer of different materials would slow down the beta particles reducing the amount of energy released in form of X-rays. Among these material I would mention PVC, aluminium and copper.
- the sample will be introduced inside from the top and will rest on the tip of the gamma scintillator
- a lead cap will seal the top opening for a complete shielding
I've made a short video on Youtube showing the effectiveness and the benefits given by the shielding.
Thanks for reading,
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