boldforgold
Member
I was wondering if anyone out there has any experience with magnetic susceptibility detectors. I was reading an article about different types of detectors and found that these detectors are widely used in the food, pharma, and geological industries. I also found that magnetic susceptibility (MS) is defined as the ability of a material to be magnetized when an external magnetic field is applied. A material like aluminum is paramagnetic, so it is slightly attracted to a strong magnet and has a + positive MS. Gold is diamagnetic, so it is slightly repelled by a strong magnet and has a - negative MS. (This phenomenon is demonstrated on youtube, notably at youtube.com/watch?v=0-ex-CAjQhY). Also, I found two manufacturers of geological instruments who make MS detectors, and these look a lot like conventional detectors that measure conductivity. These manufacturers are Bartington Instruments in England and Terraplus in Canada. In their brochure,Bartington says that their MS2D search loop "can locate buried rusty cans and other items of metallic trash easily, so it is well to check that high values are from natural minerals. Coins, rings, jewelry, metal buttons, etc., can all affect measurements". Handheld units are also available, I believe, from Terraplus. My question is, could a conventional metal detector and a MS detector be used together to discriminate pulltabs? The conventional detector would locate a target in the pulltab range, and then the target would be scanned by a MS detector. If the reading is positive, it might be a paramagnetic pulltab. If the reading is, let's say, negative or neutral it might be a diamagnetic gold ring or some other metal, but probably worth digging up. Could anyone tell me if this is possibly a valid idea, or is there some physical or practical reason why it would NOT work? Thanks for reading.