296
ScintiPack™ Photomultiplier Base
with Preamplifier and HV Supply
ORTEC
The ScintiPack Photomultiplier Base (Model 296) includes
everything needed for scintillation
detectors in one compact
package: a low-power, adjustable, high-voltage supply, an active
bias network, and a spectroscopy preamplifier. Incorporating the
bias supply in the photomultiplier base eliminates high-voltage
cable connections to bulky, external, HV supplies. As a result,
the ScintiPack operates with extremely low power consumption
(240 mW). This makes the ScintiPack attractive for portable
applications, as well as for high-density
detector arrays.
Because the preamplifier output signal is bundled into the
power cable, only a single cable is required between the
photomultiplier base and the main amplifier location. The
optional Signal Break-Out Adaptor can be used with amplifiers
that do not offer signal interfacing through the preamplifier
power plug. The adaptor attaches to the preamplifier power plug
at the amplifier, and supplies the preamplifier signal on a
coaxial cable for connection to the front-panel input of the
amplifier. This approach maintains a single-cable connection
from the ScintiPack to the amplifier location.
The ScintiPack biases the cathode of the associated
photomultiplier tube at ground potential, and the anode at a
positive voltage. The voltage applied to the anode can be
optimized within the range of +600 V to +1100 V via a 20-turn
screwdriver adjustment. This provides a cost-effective means of
adjusting and matching photomultiplier gains in large arrays of
scintillation
detectors. The dynode bias network applies 1/6 of
the anode voltage between the cathode and first dynode, and
1/12 of the anode voltage between the remaining pairs of
electrodes. To provide excellent gain stability at high counting
rates, the voltages applied to dynodes 8, 9, and 10 are
transistor regulated. Feedback regulation is also applied to the
anode voltage to achieve optimum gain stability for the entire
photomultiplier tube.
The signal from dynode 10 is integrated on a 500-pF capacitor
at the preamplifier input, amplified by the preamplifier gain, and
presented as a positive-polarity pulse at the PREAMP output. A
jumper on the printed circuit board allows selection of a
preamplifier gain of X1 or X6. The preamplifier output signal can
be accessed on pin 3 of the power connector, or at the BNC
connector on the rear panel of the ScintiPack.
The anode signal is available on a rear-panel BNC connector to
facilitate high resolution timing in coincidence measurements.
This output is intended to drive a 50-Ů coaxial cable to a timing
amplifier or a timing discriminator. By moving a jumper on the
printed circuit board, the anode output connector can be
converted to a test input for the preamplifier. A pulser can be
applied to the test input to check the operation of the entire
chain of electronics, starting from the preamplifier input.
The PMT socket is a standard JEDEC B14-38 socket that fits
10-stage photomultiplier tubes with 14 pins. Figure 1 defines
the pin assignments, and Figure 2 illustrates the connections.
The Model 296 ScintiPack Photomultiplier Base is compatible
with the photomultiplier tubes listed in Table 1. Compatibility
with tubes not listed in Table 1 can be checked by reference to
Figures 1 and 2, and by comparison with the photomultipliers
listed in the table.
Everything Needed for a Scintillation Detector . . .
• For scintillation
detectors employing 10-stage PMTs that fit
standard 14-pin sockets
• Internal, adjustable, high-voltage bias supply eliminates highvoltage
cables
• Integral spectroscopy preamplifier avoids dangling boxes
• Active bias network minimizes peak shifts at high counting
rates
• Anode timing output for coincidence measurements
• Low power consumption (240 mW) for portable applications
• Convenient, single-cable connection for most applications
. . . In One Compact Package
®
