Using TIGRESS Detectors with Ortec 660 HV
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[edit] Prototype (Serial # 1)
[edit] Instructions
- Set the Shutdown mode jumper in the 660s to TTL.
- Set the switch on the Fanout Box to TTL mode. Verify this by measuring ~ 750 Ω across the output.
- Connect the Clover Serial #1 BSD output (SMA) to the Fanout Box input (LEMO).
- Connect Fanout Box outputs (LEMO) to the 660 shutdown inputs (BNC).
[edit] Why?
The prototype generates a "TTL-High" signal to indicate "OK to BIAS". It's actually a 5 V drop across a zener diode. The 750 Ω resistor shunted across the signal makes sure that the inputs are pulled down to Low and the detector shuts off in the case of, for example, loss of preamplifier power.
[edit] Production (Serial # 2+)
[edit] Instructions
- Set the Ortec 660 shutdown mode jumpers to ORTEC.
- Set the switch inside the Shutdown Fanout Box to ORTEC mode. Verify this by checking that there is an open circuit (very high impedance) across the outputs.
- Connect the Clover Shutdown Signal (2-pin Lemo-00) to the 2-pin header input on the Bias Shutdown Adaptor Box. One header output of the "usual" 2-pin-Lemo-to-four-headers cable will work.
- When the red LED on the front of the panel glows, the shutdown signal indicates OK to operate.
- Connect the output of the Bias Shutdown Adaptor Box (Single-Pin Lemo-00 on a small white RG174 cable) to the Shutdown Fanout Box input.
- Connect the outputs of the Shutdown Fanout Box (Lemo-00) to the Ortec 660 Shutdown inputs (BNC).
[edit] Why?
Standard ORTEC preamplifiers assert that the detector is safe to operate by providing a -24 V output. If a short circuit, open circuit, or any voltage above some threshold is seen at the input of the 660, it will go into Shutdown mode and disable the HV. The production TIGRESS clovers have a closed relay contact to indicate OK to operate. The adaptor box simply uses the closed-contact relay output from the production TIGRESS clover to drive a relay. When the relay is energized, the LED comes on, and -24 V is applied to the shutdown inputs of the 660s. When the relay is de-energized, the normally-closed contact of the relay connects a shunt resistor across the inputs, and causes the 660s to go into shutdown mode.
