Detector Boards
Gem-5 User’s Manual 343
There are five connectors on the Digital Board:
• J3: 10-wire ribbon cable connector (polarized) to (optional) LED board;
• J1: 14-pin stacking connector to the Analog Board;
• J4 and J5: 16-wire ribbon cable connectors (polarized) for the daisy chained
connection with other detector boards in the system.
• J2: FPGA programming header
Gamma Detector Analog Board (SCN 816107)
The Analog Board contains the following circuitry:
• Charge sensitive preamplifier (input of sensitivity 20mV/pC) - based on the
high speed, low noise FET input operational amplifier;
• Shaping amplifier that ensures proper signal conditioning (signal
amplification and bipolar shaping with the time constant of 1µs): first
differentiator/gain stage, integrator, second differentiator/gain stage;
• Discriminators: Lower Level Discriminator (LLD) and Upper Level
Discriminator (ULD); both discrimination levels are programmable (DAC on
the Digital Board);
• Test Pulser - based on a high speed, low capacitance MOSFET switch,
analog voltage for which comes from the programmable DAC on the Digital
Board, and which is gated by the pulses coming from the FPGA located also
on the Digital Board; the circuitry is enabled during the Amplifier Pulse Test.
The pulser is calibrated in such a way that for a given pulser amplitude
setting the amplifier output should produce output pulses of the same
amplitude;
• High Voltage Power Supply - programmable in the range 0-1500V - which is
based on the self oscillating HV inverter with the output voltage multiplier,
low voltage regulating transistor (Q1) with the current limiter , error
amplifier, HV divider buffer and the HV software controlled on/off switch.
High voltage output is factory calibrated by the trimpot.
There are three connectors on the Analog Board:
• J1: 14-pin stacking connector to the Digital Board (bottom entry) that
provides power to the Analog Board and all control and feedback signals
between Analog and Digital Boards;
• J2: signal input connector (signal from the PMT HV Divider Board);
• J3: HV output connector (HV to the PMT HV Divider Board).
To Next Page
Loading...
Need help?
General
