why can beta, gamma, alpha penetrate paper, aluminum and lead?
Yes, if you just stand behind oneif you are trying to hide from an aircraft it might be harder; I'd assume a blanket would spread the heat out over a wider areaMaybe the military have camoflage ones that look a random shape, but it's hard to hide the heat source against a cold backgroundA thermal imaging camera is the same as passive infrared (microbolometer)The cameras cost about $5000 I think and work in the far infrared What is often sold as a infrared camera is just a regular CCD digital camera with a filter, and works in the near infra-red but needs an IR illiminator, like a LED array.
It would for a short while until your body heat warmed the material, however the camera operator would notice the unusual shape of the blanket, which would be abnormal to the surrounding ground temperatureIf its cooler, it would also stand out
If you disable the camera,yesTrying to pass through a thermal camera is NOT going to be easy.You would have to constantly adjust your temperature which is just not do-able, you'll be detectedCraig, you forgetNot everyone is 98.6 degrees at all times and you also forget that certain regions of your body will be higher/lowerHigher in the crotch, and armpits, and colder in the finger tips and the like.
If you wrap them around your body? No, as they would soon get warmed up to body temperature.
At the same time you could ask why are different types of radiation stopped by these barriersAlphas (flying He nuclei) can be stopped by most anything, paper, skinThey deposit their energy in a short spaceBetas go a little further because they are less massive, water will stop themGammas are massless and are very energeticThey are not spoken of as stopped, but as attenuatedLead, being very dense as a barrier, can't stop gammas, only attenuate themThis means cut down the intensity of the beam of gammasThe importance of knowing the stopping ability is in shielding designs for nuclear reactorsA combination of shielding material is used to protect workers and the public in general.
