A radiation detector having a sensitive area of Ad4106m2is

Chapter 12, Problem 12.88

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A radiation detector having a sensitive area of Ad?4?10?6m2is configured to receive radiation from a tar- get area of diameter Dt?40 mm when located a dis-tance of Lt?1 m from the target. For the experimentalapparatus shown in the sketch, we wish to determine theemitted radiation from a hot sample of diameter Ds?20 mm. The temperature of the aluminum sample isTs?700 K and its emissivity is ?s?0.1. A ring-shapedcold shield is provided to minimize the effect of radia-tion from outside the sample area, but within the targetarea. The sample and the shield are diffuse emitters.(a) Assuming the shield is black, at what temperature,Tsh, should the shield be maintained so that itsemitted radiation is 1% of the total radiant powerreceived by the detector?(b) Subject to the parametric constraint that radiationemitted from the cold shield is 0.05, 1, or 1.5% ofthe total radiation received by the detector, plot therequired cold shield temperature, Tsh, as a functionof the sample emissivity for 0.05? 0.35.