London -  Researchers at the Technion-Israel Institute of Technology have discovered six new polymorphic crystalline structures of triacetone-triperoxide (TATP), the easy to make but difficulty to detect explosive, thought to be used in the July 2005 London bombings and increasingly used by terrorists worldwide.  The findings, which were published online on 24 May in ACS Crystal Growth & Design, will make it easier to detect TATP, even when it is concealed.   TATP was previously believed to have just one crystalline form.  However, using methods that include X-ray crystallography (which reveals the arrangement of atoms within a crystal), Professor Ehud Keinan of the Technion Faculty of Chemistry and colleagues have found the explosive can form at least six different types of crystals depending on the conditions during its synthesis and crystallization.  The discovery of new forms of the explosive will now make it easier toentify using    x-ray and other techniques.   Professor Keinan, who is also President of the Israel Chemical Society, explained that TATP is popular among terrorist organisations because it is one of the few explosives which is explosive when wet or kept underwater, is made of quite easily from cheap materials and is difficult to detect.   The Technion team previously developed a device forentifying traces of TATP and other peroxide-based explosives.  The Peroxide Explosive Tester (PET), which reembles a three-colour ballpoint pen, changes colour when it has been in contact with explosive samples.   Professor Keinan commented " One way to detect certain kinds of explosives is a method called x-ray powder diffraction.  Each of these crystals has its own distinct structure, andentifying six, and very possibly more of these polymorphs, is a big step toward more reliable TATP detection."