• For use with 10-stage PMTs that fit standard 14-pin sockets
• Built-in low-noise preamplifier and focus control
• Both preamplifier output and anode output
• Test input for system testing
• Protection circuit for internal transistors
• Internal gain adjustment

The ORTEC Model 276L Low Power Photomultiplier Tube Base and Preamplifier incorporates an integral low-noise preamplifier, a PMT base with a low-power voltage divider network, and a focus control for optimum performance in scintillation detector applications. The unit is ideally suited for use with NaI(Tl) detectors.

The Model 276L provides two outputs: the preamplifier output for energy analysis and the anode output for either timing or auxiliary energy analysis. The preamplifier is dc-coupled to simplify pole-zero cancellation in the main amplifier. A Test input accepts the output of a pulse generator to calibrate and test the preamplifier and the following system. The Model 276L has a diode protection network to prevent damage to the internal transistor due to sudden application or removal of high voltage to the unit. A simple internal modification in the unit allows the gain to be adjusted for any value desired by the user. The Model 276L is powered from any ORTEC main amplifier or preamplifier power supply.

The Model 276L is directly compatible with many commercially available integrated NaI-PMT assemblies including:

• ORTEC Model 905-1, -3, and -4 NaI(Tl) Scintillation Detector Assemblies
• Bicron Model 2M3 and 3M3 Monoline Spectrometers
• Harshaw Model S288 and S332 Integral Line Assemblies
• Teledyne S-88-I and S-1212-I Integral Assemblies

Also, the Model 276L is directly compatible with 10-stage PMTs that fit standard 14-pin sockets including those listed in Table 1 of the Model 296 data sheet.

The Model 276L is also compatible with other 10-stage tubes not listed in Table 1 (see Fig. 1). Compatibility may be determined by comparison with those listed.

Fig. 1 JEDEC B14-38 PMT Pin Base, with Pin Assignments:

ORDERING INFORMATION