CG Camara et al. Nature 455, (2008) Apparatus for studying high-energy emission from peeling tape. Sticky Tape X-rays

3M Scotch Tape (19mmX25.4m) secured to a ball-bearing mounted on a stage supported by two spring leaves. The displacement was measured with a inductor. All X-ray data were acquired at a pressure of~10 -3 torr and at a peel speed of ~3 cms -1. X-ray energy emissions were recorded with X-ray detectors and with liquid scintillators. Radiofrequency signals were recorded with antennas made of the exposed inside conductor of BNC cables.

Correlation between X-rays, force and radio frequency a, Force for peeling tape at 3 cm s -1 in a torr (black line) and at 1 atm (dashed green line). X-ray signal (blue trace) from an Amptek detector. Red upper trace is the r.f. antenna signal. b, Correlation of liquid scintillator (blue line) with r.f. (red line) from peeling tape. The rise time is ~ 5 ns for the tape signal (blue line).

Spectrum of X-ray energies from peeling one roll of tape. The peel speed was between cm s -1 at torr of air. Acquired with the Amptek XR-100 CdTe detector. Inset: energies for ns pulses out to 10 GeV taken with the Amptek 3-Stack detector

X-ray burst The spectrum of X-ray burst energies that accompany slip events out to 10 GeV. These pulses occur at a rate in excess of 1 Hz and their time traces fall within the 5-ns resolution of the liquid scintillator detectors. The spectrum did not change significantly during ten rewindings of a given roll of tape.

Triboluminescence This kind of energy release occurs whenever a solid is crushed, rubbed or scratched. A long-known phenomenon, seen by English scholar Francis Bacon in He wrote that all sugar, whether candied or plain, if it be hard, will sparkle when broken or scraped in the dark. it was observed that when mica is split under vacuum. This insight led to the discovery in 1953 that peeling tape is a source of X-rays.

Tribocharging The leading explanation posits that when a crystal is crushed or split, the process separates opposite charges. When these charges are neutralized, they release a burst of energy in the form of light.

By peeling pressure-sensitive adhesive tape one realizes an everyday example of tribocharging and tribo- luminescence: the emission of visible light. The fundamental energy that holds tape to a surface is provided by the van der Waals interaction. This energy is almost 100-fold smaller than the energy required for generating a visible photon, yet, as demonstrated in 1939, light emission from peeling tape can be seen with the unaided eye. Sticky Tape visible light

Peeling sticky tape produced X-rays As long ago as 1953, a team of scientists based in Russia suggested that peeling sticky tape produced X-rays. But "we were very sceptical about the old results," says Escobar. His team decided to look into the phenomenon anyway, and found that X-rays were indeed given off, in high-energy pulses.

Vacuum the X-rays were only emitted when the kit was used in a vacuum. “We don't want to scare people from using Scotch tape in everyday life.”

Image of a finger When we place a small plastic window in vacuum chamber, we are even able to take an X-ray image of a finger, using a dental X-ray detector.

Nanosecond X-ray pulse Scientists calculate that this charge was ten times greater than typically seen in similar experiments. "We are not exactly sure why the tape is so heavily charged," Escobar says. "Of the total electron discharges, only 1/10000 makes X-rays," says Escobar. The energies of the individual X-ray pulses, typically a few nanoseconds long, are about 15 keV. The emission originates from a submillimetre region.

This concentration of diffuse mechanical energy into electromagnetic radiation has previously been observed to extend even to X-ray energies. 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. Concentration of mechanical energy

Stick–slip motion We have observed two timescales in dynamic tribocharging: - long timescale: average charge densities ~10 10 e cm -2 - transient timescale: ~1ns, concentrates charge to ~10 12 e cm -2 The physical process whereby such a large concentration of charge is attained involves the surface conductivity of the tape. This conductivity could be provided by mobile ions or perhaps by means of precursor discharges stirring up the surface of the peeling tape.

Trigger nuclear fusion Researchers suggest that the high charge density generated by peeling the tape could be great enough to trigger nuclear fusion. The charge density is about the same as the effective charge that accumulates on the surface of pyroelectric crystals used to generate table-top nuclear fusion. Loughlin, a nuclear analyst at the international nuclear fusion experiment, ITER, in Cadarache, France, is sceptical. But he adds that if he is proved wrong, a system that could provide fusion reactions at the flick of a switch would be very useful.

Editor's Summary Everyday examples include sugar cubes or candies, and many adhesive tapes will emit a flash of light when they are ripped from a surface. The energy released by peeling sticky tape in a vacuum was observed to extend into the X-ray regime, and was of sufficient intensity to be used for X-ray photography. The energy concentrating process poses an interesting challenge for the theorists.

Comments What about the static generated with some fabrics? If it is done in vacuum, would it generate x-rays? It also may be material specific too. Meaning it only occurs when the "right" mixture of chemical and atomic proprieties are involved. If X-rays can be created by something as benign as sticky tape maybe there is no need for scientists to allege that galactic black holes create the X-rays seen in space. This discovery may be proof that black holes do NOT exist.

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