The Slope Box

The Slope Box

The slope box (or sloped box, take your pick) is the interface between the control & monitoring system and the detector. The slope box takes DC power from the VXI system and generates the bias voltage for the Ge detector (typically around 3500V) plus also the lesser bias voltage for the BGO detectors (~750V - 800V). The HV supplies of the slope box are programmable through EPICS. A demand HV value is written to a DAC in the slope box and the HV is a multiple of the DAC voltage. The slope box also has a multiplexed ADC that measures detector temperature, actual HV being applied and values of the various power supplies.

In the current (as of April 2019) implementation of Gammasphere, the slope box is intimately associated with the VXI modules in the 'shack'. The VXI modules provide DC voltage and a serial interface to the slope box, and a processor board (an IOC, in EPICS parlance) converts changes in control process variables into serial messages to the slope box. These messages include commands to set the DAC or to read out the ADC.