A light amplifier, used with a scintillation crystal to detect gamma rays.
An electronic device that through a series of internal stages multiplies the small current that is given off when light is incident on the device so that a relatively large current results.
Used with a scintillation crystal to make up a scintillation counter. The flash of light produced in the phosphor of a radiation detector strikes the sensitive surface of a photocathode in the photomultiplier, causing the emission of a number of primary electrons. These electrons are drawn to an anode maintained at a higher potential, and a number of secondary electrons are emitted for each impinging electron. The secondary electrons are drawn to a second anode maintained at a higher potential than the first. whereupon additional multiplication occurs. This process is repeated in about ten stages until the initial current has been multiplied about a millionfold. The amplitude of the output of the photomultiplier is proportional to the intensity of the scintillation in the phosphor. See also scintillation counter.
(CT) An instrument containing a photoelectric cell and a series of electrodes, used to detect and amplify the X-ray signal that penetrates the body.
A photomultiplier is a device in which incident photons create measurable electrical pulses. The device is based on the photoelectric effect. It uses large electric fields to accelerate electrons and, through a cascade sequence, amplify the signal. When it is large enough it can be sent to electronic circuitry for analysis and display.
an electronic sensing device which is designed to identify a wide range of frequencies and intensity levels of electromagnetic energy
A highly sensitive electronic component, used in many color scanners, that transforms variations of light into electric currents.
(Also known as a photomultiplier tubes [PM]) or phototubes for short) extremely sensitive detectors of light in the ultraviolet, visible and near infrared. These detectors multiply the signal produced from the incident light from which single photons are detectable.
Electronic tube in which light is amplified without interference (noise) to produce an electrical signal.
a device which detects dim light by producing a cascade of electrons
Commonly used device for detecting photons by converting them to an electrical signal.
the most often used detector in an AA instrument. It consists of a vacuum tube containing an alkali-element photocathode that produces electrons when struck by photons of sufficient energy (the photoelectric effect). Each photoelectron is then multiplied by collisions with a series of dynodes so that the electrical signal produced by each photon is greatly amplified. [ photo
(PM): A photo cathode having extremely high stability and capable of reading low level light measurements in the entire part of the visible spectrum (as well as some non-visible radiation). PM's are capable of reacting to extremely short duration exposures of light as well as continuously changing conditions of light values. These PM's can read, disseminate, boost up signal and pass the information along (in microseconds) to the color computer where these signals are adjusted to conform and create the necessary color balance and depth of color to make the final separation. The photomultiplier is located in a group of four in the scanners head and measures the light transmitted through or reflected from the original copy and through corresponding color filters to create the color printers.
Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible and near infrared. These detectors multiply the signal produced by incident light by as much as 108, from which single photons can be resolved. The combination of high gain, low noise, high frequency response and large area of collection have meant that these devices still find applications in nuclear and particle physics, astronomy, medical imaging and motion picture film scanning (telecine).