Diamond Detectors for Ionizing Radiation - HEPHY

CHAPTER 7. RADIATION HARDNESS 46
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
10 -4 10 -3 10 -2 10 -1 1 10 10 2
Figure 7.8: The d c development with photon irradiation, normalized to the initial unpumped
value.
normalized charge collection distance [ ]
1.2
1
0.8
0.6
0.4
0.2
0
0 1 2 3 4 5
(24 GeV/c protons) fluence [10 15 /cm 2 ]
Figure 7.9: The charge collection distance vs. proton uence, normalized to the initial pumped
value.
This is in qualitative agreement with the observed d c decrease.
A coarse estimation suggests that diamond detectors are technically feasible as tracking
detectors up to a hadronic uence of at least 10 15 particles cm ,2 , ten times more than
present silicon detectors allow.
As discussed with the pion irradiation (section 7.3.1), diamond samples with higher
initial collection distance are more aected by radiation than those of low quality. Furthermore,
this also applies to regions of higher and lower local collection distance within a
single sample. Thus, the irradiation has almost no eect on the rising edge of the Landau
distribution. For the potential application as a detector with a certain trigger threshold
at a few thousand electrons, the eciency is less aected than suggested by the collection
distance decrease.
Alpha particles are known to damage solid state detectors by a factor of 100 to 1000
more than minimum ionizing particles. The measured data agrees with this factor.