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--- hv_bias [2014/11/19 11:43]
pereira [General Information]
+++ hv_bias [2014/11/19 11:53]
pereira [Object Scintillator]
@@ Line 15: / Line 15: @@
-===== Object Scintillator =====
+=====
-The bias for the object scintillator is controlled via the H.V. power supply {{:wiki:Manual_Canberra_HV_3002D.pdf|Canberra model 3002 D}} located in the crate to the right of the data-U6. The voltage will be adjusted at the beginning of the experiment. This scintillator has to be turned off or put on "standby" when entering the vault due to its sensitivity to light.
+Apart from the detectors listed above, the voltages of the object scintillator and the electrostatic gate of the CRDCs are adjusted manually.
+The bias for the object scintillator is controlled via the H.V. power supply {{:wiki:Manual_Canberra_HV_3002D.pdf|Canberra model 3002 D}} located in the crate to the right of the data-U6 (see figure below). The voltage will be adjusted at the beginning of the experiment. This scintillator has to be turned off or put on "standby" when entering the vault due to its sensitivity to light.
+In order for the CRDCs to work, it is necessary to bias their electrostatic gate. This is done via the H.V. Tennelec power supply located on the left side of the object-scintillator Canberra power supply (see figure below).
+{{:wiki:nim-crate2-du6.jpg?400|NIM crate 2 in data-U6}}
 ===== FP Scintillators =====
 Only the fist two scintillators are typically used since in most cases particles do not reach beyond the second detector. The biases for the anode and the drift electrode are each controlled separately via the S800 Detector HV Control. To protect the scintillator PMT bases from damage from discharge under poor vacuum conditions (for example, during a window break on one of the nearby gas detectors), the 12-Volt supply for the PMT bases is interlocked to switch off if the pressure in the focal plane box rises above some minimum value as read by an ion gauge. The ion gauge controller (a black box with an LED digital display) is mounted on the south support structure for the focal plane chamber.  The interlock condition is communicated to the PMT bias supply via a multi-pin “D” connector on the back of the controller. If the ion gauge is off, the interlock condition prevents biasing of the scintillator. It is possible to manually override the interlock condition for testing by connecting a “cheater” connector in place of the ion gauge controller to the cable for the interlock.

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