A COMPACT HYBRID PHOTODETECTOR (HPD)

In order to be utilized in such application fields as high energy phys ics or medical imaging, where a huge number of photodetectors are asse mbled in designated small area, the world's smallest hybrid photodetec tor (HPD), the compact HPD, has been developed. The overall diameter a nd the length of the tube are 16mm and 15mm, respectively. The effecti ve photocathode area is 8mm in diameter, At applied voltage of -8kV to the photocathode, the electron multiplication gain of a PD incorporat ed HPD (PD-HPD) is 1,600, and that of an APD (APD-HPD) is 65,000. In t he pulse height distribution measurement, photoelectron peaks up to 6 photoelectrons are clearly distinguishable with the APD-HPD. Experimen ts established that there was no degradation of gain in magnetic field s up to 1.5T, an important performance characteristic of the compact H PD for application in high energy physics.