This week in one of most famous scientific journals has been published this report:
Camara CG, Escobar JV, Hird JR, Putterman SJ, "Correlation between nanosecond X-ray flashes and stick–slip friction in peeling tape.", Nature 455, 1089-1092 (23 October 2008) | doi:10.1038/nature07378
Relative motion between two contacting surfaces can produce visible light, called triboluminescence. This concentration of diffuse mechanical energy into electromagnetic radiation has previously been observed to extend even to X-ray energies. Here we report that peeling common adhesive tape in a moderate vacuum produces radio and visible emission, along with nanosecond, 100-mW X-ray pulses that are correlated with stick–slip peeling events. For the observed 15-keV peak in X-ray energy, various models give a competing picture of the discharge process, with the length of the gap between the separating faces of the tape being 30 or 300 mum at the moment of emission. The intensity of X-ray triboluminescence allowed us to use it as a source for X-ray imaging. The limits on energies and flash widths that can be achieved are beyond current theories of tribology.
If you peel a tape in vacuum, it's emit X-ray which can be detected with a Geiger or a photo-film.
Please watch the video http://www.nature.com/nature/videoarchive/x-rays/