Photomultiplier Tubes: Noise Equivalent Power Analysis

This lecture focuses on the noise equivalent power (NEP) of photomultiplier tubes (PMTs). The instructor begins by identifying various noise sources within PMTs, including signal noise, shot noise, dark current, and electronic noise. The discussion emphasizes the significance of dark current and its impact on the overall performance of PMTs. The instructor provides calculations for dark current and shot noise, illustrating how these factors influence the detection limits of PMTs. An example from the Hamamatsu Handbook is referenced to demonstrate typical values for gain and dark current. The lecture also explores the relationship between the intensity of light detected and the distance from the light source, concluding that PMTs can detect light from significant distances under optimal conditions. The importance of cooling PMTs to reduce dark current is highlighted, as well as the resulting improvements in detectivity. The session wraps up with a summary of the NEP calculations and their implications for practical applications of PMTs in optical detection.