The SVTRAD system consists of 12 PIN diodes grouped into 4 modules: Forward West, Forwad East, Backward West, and Backward East. Each module contains a MID (middle) plane diode, located in the bending plane of the magnet, as well as a TOP and a BTM (bottom) diode located respectively above and below the MID plane. The temperature of each diode is measured by 2 surrounding thermistors.
The output current from a PIN diode, apart from a pedestal current that has to be
subtracted, is proportional to the instantaneous radiation dose.
In 2002, two diamond detectors of roughly the same size as the PIN diodes were installed in the backward end of the support tube. For those diodes the pedestal currents are lower and are almost independent from the temperature. These diamond detectors provide a measurement of the instantaneous radiation dose much more reliable that the other diodes.
The SVTRAD is the only subsystem that can abort the beams. That can happen in different cases:
The following plots show the radiation dose integrated by the SVTRAD diodes.
The following plots show the number of stable beams aborts or aborted injection due to SVTRAD for each day in the last two weeks. The left column is relative to fast aborts: upper plot for the injection, lower plot for stable beams. On the right are shown the number of timer activations (up) and the number of minutes on timer.