A compactrio-based beam loss monitor for the SNS RF test cave

An RF Test Cave has been built at the Spallation Neutron Source (SNS) to be able to test RF cavities without interfering with the SNS accelerator operations. In addition to using thick concrete wall to minimize radiation exposure, a Beam Loss Monitor (BLM) must abort the operation within 100 usec when the integrated radiation within the cave exceeds a threshold. We chose the CompactRIO platform to implement the BLM, based on its performance, cost-effectiveness, and rapid development. Each in/output module is connected through an FPGA to provide point-by-point processing. Every 10 usecs, the data is acquired, analyzed, and compared to the threshold. Data from the FPGA is transferred using DMA to the real-time controller, which communicates to a gateway PC to talk to the SNS control system. The system includes diagnostics to test the hardware and integrates the losses in real-time. In this paper, we describe our design, implementation, and results.