Desktop shield

[Lposter]

This is a shield I built for one of the Radiacode devices. I was sick of the low energy background without a shield and need one that would reduce that and be able to stand on my desk without being really intrusive.
I had 40 kg of 400 year old lead, some tin and copper.

I thought I needed more tin so I bought some of those pewter sheets (Green Art or whatever). When they arrived I noticed they were actually lead sheets coated with pewter/tin so I was not too happy about that. In the end I used them but only outside a layer of pure tin.

I used an old cookie tin from Heidelberg and an aluminium pot I had from something else. The pot went inside the cookie tin as a mold. The volume between the two was about 1 liter. Then lead was poured between the two. Overall wall thickness approaches 2 cm.

Then teh inside was lined with some pewter foil, 1 mm pure tin and 0.5 mm pure copper. The lid of the cookie tin was filled with lead, then molten tin was poured over that, then a disk of copper fitted. A large hole was the cut in it.

Then a second little pot was made from lead in a bean can and this was fasted to the overall lid. This will hold the rear of the Radiacode. A hole was drilled for the cable.

Compared to no shield at all, background drops from 12 cps to 0.5 cps. Some Cu x-rays are still evident in teh background. A layer of aluminium or plastic may get rid of those but I am not too fussed really.

Overall weight must be about 15 kg. Easily moveable but does not hold big samples. This does not bother me as I do not have any big items.

Otherwise...happy with it. Cost very little, does its job and if I ever have to get rid of it, its not a major job.

Lars

[Sesselmann]

Lars,

Nice tidy project and it looks like you are getting a good result...

Are you finding any interesting sources in Oslo?

Last time I was in Oslo, about a year and a half ago, I carried the Atom-swift in my pocket, and the only place the alarm went off was in the Vigelands park, walking up the steps to the monolith, plenty of granite there.

[Lposter]

We have some granite buildings - there is a old bank building on Karl Johans Gata that was pretty lively ...... there is a stone from Hiroshima as a memorial in the city which is, ironically I suppose, not active at all.

We are not far from the Fen felt which is a place where they used to mine niobium and has a big NORM problem today. Lots of thorium and uranium minerals as well as slag lumps from the processing of niobium which can be very active. Most of the really hot lumps have been snapped up by other people over the years though. Always interesting to wander around there.

Here is some background:

https://fensfeltet.no/en/det_radioaktiv ... ve_gruver/

Its full of other rare earths up there so I am guessing it is going to be an interesting place for those sort of things in the future.

And if I have time, the places that got most of the Chernobyl fallout is a few hours away and mushrooms or reindeer from there always have measurable Cs.

Otherwise it is fairly normal!


Lars

[ColoRad-o]

Nice job! It must be nice to live in a country where 40 kg of 400 year old lead is available—what is that, from the keel of the Vasa? :)

The cable is for charging only? I have yet to attach my RC 103g directly to a computer...Do you have any trouble punching through a Bluetooth connection? (I have about 40 kg of lead SHOT in my shielding but have had no problem communicating with the RC.). --DMW

[Lposter]

I got the lead from a whole body counting room that was being dismantled a decade ago....was probably many tons of the stuff but they were building a new one and reusing the lead and I just managed to grab a few blocks. They were just sitting in the garage waiting for their time....

When that room was built (late 1950s I guess) it was easier to get old lead as there was lots of it around from houses and buildings that had been knocked during the war and so on - they all had lead around windows and so on, there were lead pipes etc.......

Nowadays you are lucky to have a cm or so of old lead inside 9cm or so of new lead on a standard 10 cm lead shield.

I use the cable for signal and power........I found my Bluetooth signal was not getting through the copper tin lead combo for some reason (maybe its not supposed to?) but it could equally be a problem on the computers side.

Plus....I have a tendency to leave things running for weeks and I dont want the battery to fail on me midcount. So I simply use the cable. Bit old fashioned like that......

Lars