Back-end Electronics for Low Background and Medium Scale Physics Experiments Based on an Asymmetric Network

TL;DR

This paper presents a low-background, medium-scale detector readout architecture using an asymmetric network with point-to-point links and a common fanout, optimized for simplicity, low material budget, and moderate bandwidth needs.

Contribution

It introduces a novel asymmetric network architecture with a shared fanout and point-to-point links, and details a back-end control unit capable of managing 32 front-end modules at high bandwidth.

Findings

Supports up to 12.8 Gbps aggregate bandwidth

Flexible communication media options including fiber and copper

Simplifies system design for low-background physics experiments

Abstract

The detector readout architecture introduced in this paper is intended for small to medium size physics experiments that have moderate bandwidth needs, and applications that require an ultimately low background radioactivity for the parts close to the detector. The first idea to simplify the readout system and minimize material budget is to use a common fanout structure to transport from the off-detector back-end electronics all the traffic required for the synchronization, configuration and readout of the front-end electronics. The second idea is to use between each front-end card and the back-end electronics a point-to-point link that runs at the relatively low speed that suffices for the target application. This broadens the possible choices for the physical media of the communication links, e.g. glass fiber, plastic optical fiber, or copper. This paper presents a communication protocol adequate for the proposed asymmetric network and shows the design of a back-end unit capable of controlling 32 front-end units at up to 12.8 Gbps of aggregate bandwidth using an inexpensive commercial FPGA module where the large number of regular I/O pins interface to the front-end links, while the few available multi-gigabit per second capable transceivers are affected to the communication with the upper stage of the DAQ system.