shielding

I want to build a radiation shielded chamber for Gamma spectroscopy using my Radiacode 103. After batting some ideas about on another thread this is what I have so far: Outer case is 6mm steel (mild steel) - This could be a square tube section, or made from sheet. Inner case is the same as the outer and has 60mm x 60mm to 75mm x 75mm (thereabouts) space in the center for the Radiacode and source. Internal length of the chamber will be ~200mm. Space between the inner case and outer case will be filled with lead, ~25mm thick. Tabs/flange on both caps and outer case to put bolts through to fix

On a radmon.org forum thread we sort of got to discussing the thickness of Aluminium for shielding beta but I didn't want to divert that thread too much so started a new thread on this subject here. I had quoted, roughly in all honesty, that 5mm aluminium would do well for beta shielding and was met with this reply by user FSM19: For a beta shield you need 3mm of aluminium, foil isn't thick enough, UK Civil Defence geiger counters and ionisation instruments, such as the Meter Doserate Portable No 1 Trainer, Meter Doserate Portable No 1 and the Meter Survey Radiac No 2 had diecast bodies about

I have always been a little dubious about leaving radioactive test sources just laying around, although they emit small amounts of radiation. I knocked up a little lead lined box over the weekend to keep my test sources in. The box is just one of those cheapo wooden boxes from India (or somewhere) that you see for sale in markets and such that I lined with 2mm lead flashing (used above windows), painted bright orange with some paint left over from an old project. I added a label on top that is from a check source I bought from ebay and a radioactive symbol tie pin on the front. It works very