Diamond Detectors for Ionizing Radiation - HEPHY
Diamond Detectors for Ionizing Radiation - HEPHY
Diamond Detectors for Ionizing Radiation - HEPHY
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CHAPTER 7. RADIATION HARDNESS 44<br />
Q π /Q e<br />
6<br />
Excess Factor<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
0 20 40 60 80 100 120 140 160 180<br />
Total Fluence [E13 π + /cm 2 ]<br />
Figure 7.6: The range of the excess factor vs. uence.<br />
Up to 100 kGy of photon uence, corresponding to 10 years of LHC operation at a radius<br />
of 20 cm from the vertex (see section 2), no change in the collected charge was observed.<br />
7.3.4 Proton Irradiation<br />
In 1997, diamond samples were irradiated at the PS at CERN [37] with protons. The<br />
momentum of the protons was 24 GeV c ,1 . Another irradiation was per<strong>for</strong>med earlier<br />
with 500 MeV c ,1 protons, showing compatible results.<br />
Fig. 7.9 shows the development of the collection distance with proton uence. After a<br />
uence of 5 10 15 pcm ,2 , exceeding by far the expected LHC uence within 10 years at<br />
r = 7 cm from the vertex, the signal decrease is about 40%.<br />
7.3.5 Neutron Irradiation<br />
<strong>Diamond</strong> samples have been irradiated in 1995 at the ISIS facility at the Ruther<strong>for</strong>d<br />
Appleton Laboratory with both thermal neutrons and neutrons with energy peaks at<br />
10 keV and 1 MeV [15].<br />
The pumping process and the neutron induced damage to the charge collection distance<br />
is shown in g. 7.10. The charge collection distance normalization corresponds to the<br />
virgin unpumped state. The d c decrease is approximately 20% after 10 15 ncm ,2 , which
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