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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42 3. Ir<strong>radiation</strong> FacilityPt100 sensorCool<strong>in</strong>g liquid outletCool<strong>in</strong>g liquid <strong>in</strong>letDiodeAlum<strong>in</strong>aCool<strong>in</strong>g cyl<strong>in</strong>derKaptonBias/Pt100 connectorFigure 3.7: Schematic view <strong>of</strong> the cool<strong>in</strong>g cyl<strong>in</strong>der <strong>for</strong> sample cool<strong>in</strong>g <strong>in</strong> the F19 ir<strong>radiation</strong>channel. A sample mounted on Al 2 O 3 ceramics and a Pt100 temperature sensor is displayedtogether with the connector <strong>for</strong> bias/measurement l<strong>in</strong>es.be obta<strong>in</strong>ed <strong>in</strong> pulsed mode. To pulse the reactor one <strong>of</strong> the control rods is pneumaticallyred to a preset upper position, driv<strong>in</strong>g the reactor <strong>high</strong>ly over-critical. This results <strong>in</strong>a fast <strong>in</strong>crease <strong>of</strong> the neutron ux and heat<strong>in</strong>g <strong>of</strong> the reactor core. Temperature raisehowever causes an <strong>in</strong>crease <strong>of</strong> neutron absorption <strong>in</strong> 238 U and hardens the thermal part<strong>of</strong> the spectrum thus decreas<strong>in</strong>g the reaction rate <strong>in</strong> 235 U. Thus the pulse is stopped andthe reactor is shut down. In the pulsed mode a total uence <strong>of</strong> about 10 14 n/cm 2 can beobta<strong>in</strong>ed <strong>in</strong> around 20 ms (approximate pulse width).3.4.2 Neutron Spectrum and DosimetryThe neutron spectrum <strong>in</strong> the ir<strong>radiation</strong> channel F19 (g. 3.8) was determ<strong>in</strong>ed by simulation[38] and measurement [36].The simulated spectrum was obta<strong>in</strong>ed us<strong>in</strong>g the MCNP4B Monte Carlo simulationcode [39]. S<strong>in</strong>ce the reliability <strong>of</strong> the results depend crucially on the source description,a detailed description <strong>of</strong> the real TRIGA geometry [40] was used <strong>in</strong> the simulation. It<strong>in</strong>cluded the exact conguration <strong>of</strong> all 91 locations <strong>in</strong> the core and a detailed description<strong>of</strong> fuel elements as well as control rods. It was tested with experimental results <strong>of</strong> a criticalexperiment [41]. Very good agreement with experimental results conrms the reliability<strong>of</strong> the model developed.