Subatomic Physics

4.3. Semiconductor Detectors 61
Figure 4.8: Ideal, fully depleted
semiconductor detector
with heavily doped surface layers
of opposite types.
Figure 4.10: Gammasphere: 110 high-purity
Ge detectors were put together in a 4π array.
This photo shows approximately half of the
array around the chamber that holds the target
where the beam impinges under vacuum.
[Courtesy of A.O. Macchiavelli.]
Figure 4.9: Optimal energy resolution of semiconductor
counters as a function of energy. [From F.S.
Goulding and Y. Stone, Science 170, 280 (1970).
Copyright 1970 by the American Association for
the Advancement of Science.] FWHM means full
width at half maximum.
Figure 4.11: Developments for GRETA:
Gamma-ray energy tracking array. This detector
has 36 segments. The energy deposited
in each segment can be read separately which
allows for photon tracking. An array covering
4π would be built with several of these units.
[Courtesy of A.O. Macchiavelli.]