312 Chapter 5. Solid State Detectors
about an order of magnitude higher than detectors made of silicon (1). For diamond
the main damaging effect of radiation is the production of vacancies or energy levels
inside the band gap. These vacancies can act as electron traps and thus introduce
non-linearity and degradation in the detector response.
5.2.G Applications
As we have mentioned earlier, the biggest advantage of using diamond as a radiation
detection medium stems from its radiation hardness. Hence the applications where
semiconductor detectors have been seen to deteriorate with time due to accumu-
lated dose are the best candidates of diamond based detectors. Accelerator based
experiments of particle physics were the first where experimenters started exploiting
this feature of diamond to think about replacing the conventional silicon detectors
at places where radiation field was highest. The research is still going on in this di-
rection and the results of prototype detectors look quite promising. However a full
scale diamond detector completely replacing a silicon tracker is still not a reality.
The other field where radiation damage of detectors is a concern is the radiation
therapy, which is done by high energy particles produced in small scale accelera-
tors. The high frequency of treatment provided at these facilities requires radiation
hard detectors for dosimetric purposes. Several authors have shown that diamond
detectors can be used in such facilities more efficiently as compared to the conven-
tional semiconductor detectors and gas filled ionization chambers (see, for example
(10; 5; 6)).
Other applications where possible use of diamond detectors is being explored
include
synchrotron beam intensity monitoring,heavy-ion collision experiments, andneutron detectors for high radiation environments.5.3 ThermoluminescentDetectors......................
The term thermoluminescence stands for thermally stimulated luminescence, which
in simple words means emission of light be thermal stimulation. A thermolumines-
cent (TL) material is a kind of memory device that is capable of retaining radiation
dose information for a long time or until its temperature is raised above a certain
level. The usefulness of TL materials as radiation detectors was first realized in
early 1950s. Since that time such detectors are being extensively used in personal
dosimetry applications.
We will discuss different kinds of TL detectors in the chapter on radiation dosime-
try but it is worthwhile here to discuss the principle of thermoluminescence specially
because the principles involved are similar to those of semiconductors and diamond
we studied in this chapter.