Detection photomultiplier tube

M, dichroic mirror P, dispersive prism I, iris L, lens T, 5-axis fiber positioner PUT 1, detection photomultiplier tube ... 

The back-scattered fluorescence is collected back up the same fiber, reflected from the mirrored face of the perforated mirror (PM), and imaged by another lens onto the entrance slit of a monochromator (SLM-Aminco, Inc.) with a spectral band-pass of 8 nm. Fluorescence is detected with another photomultiplier tube (D), identical to the reference channel unit. The cross-correlation (heterodyne) frequency (16,18) is produced with a second PTS 500 frequency synthesizer amplified by a 5W power amplifier (PA2 Amplifier Research, model 5W1000). The output from this amplifier is directed simultaneously to the second dynodes of the both reference and detection photomultiplier tubes using a simple power splitter (PS Adam Russell, model H-9). The cross-correlation frequency employed for this instrument is 25 Hz. 

Liquid scintillation counting is by far the most common method of detection and quantitation of -emission (12). This technique involves the conversion of the emitted P-radiation into light by a solution of a mixture of fluorescent materials or fluors, called the Hquid scintillation cocktail. The sensitive detection of this light is affected by a pair of matched photomultiplier tubes (see Photodetectors) in the dark chamber. This signal is amplified, measured, and recorded by the Hquid scintillation counter. Efficiencies of detection are typically 25—60% for tritium >90% for and P and... 

The emitted P particles excite the organic molecules which, in returning to normal energy levels, emit light pulses that are detected by a photomultiplier tube, amplified, and electronically counted. Liquid scintillation counting is by far the most widely used technique in tritium tracer studies and has superseded most other analytical techniques for general use (70). 

Flame Photometric Detector3 With the flame photometric detector (FPD), as with the FID, the sample effluent is burned in a hydrogen/air flame. By using optical filters to select wavelengths specific to sulfur and phosphorus and a photomultiplier tube, sulfur or phosphorus compounds can be selectively detected. 

PUT 2, power normalization photomultiplier tube BS, beamsplitter D, detection optical fiber , excitation fiber TC, oven temperature controller for harmonic generation. 

A schematic cross-section of one type of photomultiplier tube is shown in Figure 26. The photomultiplier is a vacuum tube with a glass envelope containing a photocathode and a series of electrodes called dynodes. Light from a scintillation phosphor liberates electrons from the photocathode by the photoelectric effect. These electrons are not of sufficient number or energy to be detected reliably by conventional electronics. However, in the photomultiplier tube, they are attracted by a voltage drop of about 50 volts to the nearest dynode. 

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