Study of radiation damage in silicon detectors for high ... - F9
Study of radiation damage in silicon detectors for high ... - F9
Study of radiation damage in silicon detectors for high ... - F9
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26 2. Operation and Radiation Damage <strong>of</strong> Silicon DetectorsFigure 2.5: The neutron <strong>damage</strong> function <strong>for</strong> <strong>silicon</strong> accord<strong>in</strong>g to Ougouag [27]."NIEL hypothesis"the <strong>radiation</strong> <strong>damage</strong> <strong>of</strong> the bulk depends on the non-ionis<strong>in</strong>g energyloss only. This has been experimentally demonstrated <strong>for</strong> protons, neutrons and pions[13, 18, 19, 20, 21, 22].Displacement <strong>damage</strong> scales l<strong>in</strong>early with NIEL. It is given by the <strong>damage</strong> functionD(E) [25]. The <strong>damage</strong> caused by dierent particles is usually compared with the <strong>damage</strong>caused by neutrons. S<strong>in</strong>ce D depends on neutron energy (gure 2.5), the <strong>damage</strong> doneby 1 MeV neutrons is taken as a reference po<strong>in</strong>t. The standard value <strong>for</strong> the neutron<strong>damage</strong> at 1 MeV is 95 MeVmb [26]. For an ir<strong>radiation</strong> with particles A with spectraldistribution ddE and cut-os E m<strong>in</strong> and E max a hardness factor can be dened as A =R EmaxhD A iD(1MeVn) = 1D n (1MeV) E m<strong>in</strong>D A (E) d A(E) dER EmaxE m<strong>in</strong>dEd AdE (E) dE : (2.48)In order to allow a universal comparison <strong>of</strong> results it is common practice to refer tothe equivalent uence eq <strong>of</strong> 1 MeV neutrons which would have caused the same <strong>damage</strong>as the uence <strong>of</strong> particles actually applied. is converted <strong>in</strong>to eq by multiply<strong>in</strong>g itwith the hardness factor eq = A A : (2.49)