  We have developed radiation detectors using the new synthetic diamonds. The
diamond detector has an advantage for observations of "low/medium" energy gamma
rays as a Compton telescope. The primary advantage of the diamond detector can
reduce the photoelectric effect in the low energy range, which is background
noise for tracking of the Compton recoil electron. A concept of the Diamond
Compton Telescope (DCT) consists of position sensitive layers of
diamond-striped detector and calorimeter layer of CdTe detector. The key part
of the DCT is diamond-striped detectors with a higher positional resolution and
a wider energy range from 10 keV to 10 MeV. However, the diamond-striped
detector is under development. We describe the performance of prototype diamond
detector and the design of a possible DCT evaluated by Monte Carlo simulations.
