Ronan X96S MASS FLOW GAUGE - Manual (Page 65)

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Detector
Scintillator Detector
Description The Ronan scintillation detector consists of three main components: The
plastic scintillation crystal, the photo-multiplier tube (PMT), and the
associated electronics.
Scintillation Crystal The crystal used for the Mass Flow System is poly-vinyl toluene (PVT)
plastic. The crystal produces light pulses which are proportional to the
incident radiation events striking it.
Typically mounted in a stainless steel shell the entire crystal assembly is
sealed against moisture and dirt and is non-repairable. An integral flange
serves to mount the crystal to the PMT. A special silicone membrane
serves as an optical coupling medium between the crystal and the PMT.
Photo-multiplier Tube The PMT is a light sensitive vacuum tube with a photosensitive layer that
converts the light pulses to an electrical current. Light pulses from the
crystal strike the photosensitive layer and release electrons. A high voltage
power supply connected to the photosensitive layer accelerates the
electrons through stages of current amplification.
The PMT and its associated components are housed in a special magnetic
shield. The tube is shock-mounted internally, with an interface plate at the
top, which also mounts the electronics and the outer shell.
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Electronics Two to four boards (depending on the scintillator type, housed in a stainless
steel shell, comprise the electronics and their functions.
• High Voltage Power Supply
• Preamplifier
• Discriminator
• Pulse Output
Detector Service The critical components of the electronic circuit and the
PMT/Crystal Assembly are aligned before leaving the
factory. If any component of the Scintillation Detector is
adjusted or replaced, the performance of the entire system
will be adversely affected and will require realignment
before continued use is possible.
Therefore, the scintillation detector IS NOT field
serviceable. Should a problem arise with the detector, the
entire Detector Assembly should be returned to Ronan for
repair/replacement.