INSTRUMENTATION
If t i f f
Figure 3.
14 STAGE
Outstanding run on ammonia
Ammonia vapor. 10-cm. cell. Scanning speed 0.02 micron per minute. Wave-length seale 0.1 micron per inch. 2-second period. 100-mm. pressure
search investigation, it can be reduced to a "push-the-button-once" mode of operation when routine examinations are to be carried out by a technician. After the sample is inserted, a button is pushed and the complete curve is recorded. The instrument will stop automatically at the starting point for the next run. For this "push-button" operation, the instrument is set up by a qualified operator for a particular analysis. The controls for this initial setup are under the sliding panel shown at the right of the instrument (under the sloping desk front). This arrangement is to discourage itinerant dial twiddlers. The electronic components in this instrument incorporate the best modern practice. There are only 25 vacuum tubes on eight removable plug-in plates. All tubes are operated at conservative ratings and tubes and associated circuitry can be reached without removing screws. In the double-beam operation, a novel electronic integrator in the signal amplifier, with a tight positionservo around the comb motor, provides a zero dead zone in the system, even during severe solvent absorptions. This provides a smooth continuous curve rather than stepwise response. Figure 3 is an example of the structural detail that can be obtained with this instrument. It is the ammonia vapor spectrum in the 10-micron region, requiring a half-hour scan. As an example of results at high scanning speeds, Figure 2 shows the spectrum.of polystyrene over the range of 1 to 15 microns, taken in 15 minutes. More extensive data on performance have been obtained at the laboratories of Union Carbide & Carbon Corp., Institute, W. Va.
...for investigations involving unusually low-level light sources!
RCA-6810—the most sensitive phototube in the RCA line—is a head-on type multiplier phototube designed for scintillation counters, spectrophotometers, and other applications involving low-level light sources. Featuring fast response, high current gain, relative freedom from after-pulses, and small spread in electrontransit time, the 6810 is particularly useful for fast coincidence scintillation counting. Because the 6810 is capable of delivering pulse currents having magnitudes up to 0.5 ampere without appreciable deviation from linearity, the need for an associated w i d e - b a n d amplifier is eliminated in many applications. The spectral response of t h e 6810 covers t h e range from about 3000 to 6500 angstroms. Maximum response occurs at approximately 4400 angstroms. The 6810, there-
V O L U M E 2 8, N O . 2, F E B R U A R Y 1 9 5 6
fore, has high sensitivity to blue-rich light. Design Features of RCA6810 · semitransparent cathode on inner surface of tube face · face has flat surface · 14 electrostatically focused multiplying (dynode) stages · focusing electrode with external connection for shaping the field which directs photoelecfrons from the cathode onto the first dynode · accelerating electrode with external connection for minimizing space-charge effects · multiplies feeble photoelectric currents
approximately 66,000,000 times when operated with 2300 volts supply potential · short timeresolution capability in the order of 1 or 2 millimicroseconds. Designers and manufacturers of radiation detection a n d s p e c t r o photometry apparatus, and schools, institutions, and laboratories making use of such equipment can obtain complete technical data on RCA6810 and other RCA Phototubes by writing to RCA, Commercial Engineering, Sect. B-80-U, Harrison, N. J.
LABORATORY TUBES Radio C o r p o r a t i o n of A m e r i c a For further information, circle number 77 A on Readers' Service Card, page 79 A
77 A
