Diamond maker focuses on particle detectors
May 3, 2007
Coveted for their beauty and hardness, diamonds are also becoming the particle physicist's best friend. That's because diamond can outperform silicon and other semiconductors that are normally used as radiation detectors in high energy physics experiments. Now, a new company called Diamond Detectors has been spun out of the UK diamond supplier Element Six to focus exclusively on building detectors based on synthetic diamonds.
The diamonds used in detectors must be very pure but such stones are rare in nature and are difficult to grow in the lab. Having honed the technique of chemical vapour deposition, however, Diamond Detectors says it can produce high-quality synthesized diamonds, and its detectors have already been installed in CERN's Large Hadron Collider, which is scheduled to start up later this year.
Silicon detectors are often used in high energy physics to detect incoming charged particles or radiation. When a charged particle enters a silicon detector, its energy ionizes nearby atoms, creating electron-hole pairs. Because silicon is a semiconductor, these pairs are then free to move, and so they can be attracted towards electrodes surrounding the silicon to produce a measurable signal. Pure diamond, however, can also behave as a semiconductor, and if it is used in a detector it can detect particles and radiation from UV to X-rays with much less noise. In addition, unlike silicon, which must be cooled using liquid nitrogen, diamond can operate stably at temperatures well over 100 °C, making it ideal for monitoring alpha, beta or neutron radiation from hot nuclear reactors.
Since the 1980s Element Six (E6), which is named after carbon's atomic number, has been developing chemical vapour deposition (CVD) in order to produce synthetic diamonds. To make diamond via CVD, gases that contain carbon, such as methane, are passed at low pressure over a substrate, which is heated so that the gases break down and form diamond. E6 has recently refined this technique by altering growth parameters so that the diamond doesn't grow too quickly, enabling large crystals with very few imperfections to be consistently produced. Today Diamond Detectors will take over the development role and package the diamond into detectors.
"We have been selling to quite a few companies, which is why it seemed like a good time to get the business started and make it stand on its own two feet," Chris Wart, the technical manager of Diamond Detectors, told Physics Web. The firm’s customers include CERN, which has worked with E6 since 2002 and is now using the diamond detectors in the large ATLAS detector in its forthcoming Large Hadron Collider. Its detectors are also used at the Diamond Light Source synchrotron facility, which opened recently in the UK.
Diamond Detectors are also planning to create "body compatible" detectors for use in radiotherapy. These instruments will try to take advantage of the fact that the density of carbon in diamond is similar to that in soft tissue. "The applications of diamond are so diverse," Wart added. "We are getting the diamond synthesis right, and then we're investing in other 'portfolio' companies who can get on with the market channels and expertise."
About the author
Jon Cartwright is a reporter for Physics Web