Physics and Engineering of Radiation Detection

396 Chapter 6. Scintillation Detectors and Photodetectors A.16NoiseConsiderations...................... Since PMTs are very sens ...

6.5. Photodetectors 397 In the two subsequent sections we will look at the theoretical considerations of the signal-to-noise rat ...

398 Chapter 6. Scintillation Detectors and Photodetectors HereIbgis the background current, which is the average anode current m ...

6.5. Photodetectors 399 Example: If the temperature of a PMT based detector working at 200Kis elevated to the room temperature o ...

400 Chapter 6. Scintillation Detectors and Photodetectors The overall signal-to-noise ratio from these measurements is then give ...

6.5. Photodetectors 401 with analog mode where actual pulse heights are measured. In digital mode one generally uses a discrimin ...

402 Chapter 6. Scintillation Detectors and Photodetectors separate the data into the three components. What is done instead is t ...

6.5. Photodetectors 403 Similarly for the background counts we have σbg = √ Nbg = √ 1. 5 × 102 =12. 2. The total shot noise due ...

404 Chapter 6. Scintillation Detectors and Photodetectors there is a flux Φγof photons having frequencyνuniformly illuminating t ...

6.5. Photodetectors 405 The photocurrent gain is then obtained by dividingisbyiγ. Hence we get Gain = is iγ = τμE d = τ td . (6. ...

406 Chapter 6. Scintillation Detectors and Photodetectors Just like conventional photodiode detectors, the avalanche photodetect ...

6.5. Photodetectors 407 p+ n n+ Guard Ring Intrinsic SiO 2 Metal Contact Antireflective Coating p Metal Contact Photon Figure 6. ...

408 Chapter 6. Scintillation Detectors and Photodetectors approximations to this probability density function have been proposed ...

6.5. Photodetectors 409 Now, using this value ofαdwe can calculate the gain atu=0.01 as follows. 〈Ge〉 = 1 −u e−αd(1−u)−u = 1 − 0 ...

410 Chapter 6. Scintillation Detectors and Photodetectors voltage can be written as dG dV =kvG %V−^1 , (6.5.59) whereV is the ap ...

6.5. Photodetectors 411 C.3 QuantumEfficiencyandResponsivity The quantum efficiency of a photodiode detector is used to characte ...

412 Chapter 6. Scintillation Detectors and Photodetectors Example: An APD having a gain of 20 and responsivity of 8A/W is subjec ...

6.5. Photodetectors 413 photon counting capabilities. With a pulse resolution of as low as 20ps, a gain of as high as 10^8 , and ...

414 Chapter 6. Scintillation Detectors and Photodetectors It is instructive to compare equations 6.5.57 and 6.5.74, which repres ...

6.5. Photodetectors 415 whereBis the bandwidth of the system,〈Ge〉is the mean electron multiplication factor,Ieis the mean electr ...