| 摘要 |
<p>An instrument for tuning the photomultiplier (PM) tubes of a scintillation camera to the gamma ray photon energy spectrum of interest. A finely collimated beam of photons from a test isotope is placed on the scintillator crystal in alignment with the photomultiplier tubes in succession. A summing amplifier develops signals that are proportional to the total energy of scintillation events. Lower and upper level discriminators define an energy window and produce output signals, respectively, depending on whether incoming total energy signals are within or above the window level. The output signals are sent to an integrating capacitor. A sensing circuit continuously senses capacitor voltage and drives visual indicators which indicate whether the energy spectrum within the acceptable window predominates or whether energies above the window predominates and the gain of the PM tube under test is adjusted accordingly.</p> |
