28 May 09. Researchers at the Technion-Israel Institute of Technology have discovered six new polymorphic crystalline structures of triacetone-triperoxide (TATP), the easy to make but difficult 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 this week 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 to identify using x-ray and other techniques. TATP is popular among terrorist organisations around the world for two reasons – it is easy to prepare and very difficult to detect. Professor Keinan’s team at the Technion previously developed a device for identifying traces of TATP and other peroxide-based explosives. The Peroxide Explosive Tester (PET), which resembles a three-color ballpoint pen, changes colour when it has been in contact with explosive samples.