Diamonds are forever

Radioactive beam facilities of the newest generation can produce beams of rare istopes with rates up to 108 particles per second. In many experiments it would be desirable to track particle positions and measure timing properties of these intense beams on a event-by-event basis. Researchers at the NSCL and MSU's physics department developed a particle detector made from single-crystal diamond that will significantly extend the capabilities of conventional detection technology. The diamond is grown by chemical vapor deposition (CVD) at MSU's Keck Microfabrication Facility.

Figure 1 shows a preamplifier signal of a 20 micron thick diamond detector while it was irradiated with a 100 MeV/u 76Ge beam. The detector response time is fast enough that for the first time two particles within one extraction pulse of the NSCL cyclotron could be directly observed. The diamond detectors allow to measure the flight time of relativistic particles with extreme precision. In a time measurement between two single-crystal diamond detectors a timing resolution of σ=20.5 psec could be achieved. A further advantage of the single-crystal material is a high charge collection efficiency resulting in an energy resolution for relativistic charged particles of ΔE/E=18% (FWHM).

Figure 1: Preamplifier signal of a single-crystal diamond detector irradiated with a 76Ge beam. more

These detectors were successfully tested with particle rates of over 50 million particles per second. This is more than ten times the beam intensity a conventional timing scintillator could be used at. Diamond detectors are very radiation resistant and last much longer in a high radiation environment than most other detectors.

This work was supported by the National Science Foundation through grant PHY 0110253 and by Michigan State University.

Andreas Stolz
stolz at, 517-324-8121