Zinc as a substitute to copper ?

[Sebastien_billard]

Hi !

I read about the benefit of graded shields and Cu is often quoted for inner layer. That said, at least in France, it is not always easy to find in hardware stores copper pipe of large diameters, like 6 or 8 centimeters. Looking on the Mendeleiev table I see that zinc atomic number is 30 when copper is 29. So could zinc could be used instead of copper in your opinion ? Would a thickness of 0.6mm be enough to bring background down ?

My current lead castle is made of roofing lead roll, protected with aluminium foil and scotch. Around 8 kilograms.

[Sesselmann]

Sebastien,

Have you considered using a simple iron pipe?

Iron has a low energy x-ray, it's cheap and easy to find.

http://nucleardata.nuclear.lu.se/toi/xr ... list&el=Fe

Steven

[Sebastien_billard]

Hi Steven,

When you speak about iron, do you mean pure iron, or cast iron which is iron mixed with a good quantity of carbon ? I have found cast iron chimney tubes, is that the kind of tubes you are thinking about when writing"easy to find" ?

[Sesselmann]

Sebastien,

Chimney tubes or even sewer pipes should make a good lining for your lead. Cast iron is mainly Fe +C both exhibit low energy fluorescence which is below what your average gamma detector can see.

Your shielding only needs to be as good as your experiment demands.

People often take recommendations too seriously, whoever recommended that shields be made with layers of Pb, Zn and Cu was probably doing a PHD on shielding, and had to consider the whole range of photon energies, but if you are working with a detector with a range between 20 and 3000 keV then who cares about 10 keV x-rays?

Steven

[Sebastien_billard]

Thanks you very much, your comments make sense :) Yes my detector is built for 30 to 3000 keV so very low energy x rays are not really a concern.