  European Spallation Source (ESS) will deliver neutrons at high flux for use
in diverse neutron scattering techniques. The neutron source facility and the
scientific instruments will be located in Lund, and the Data Management and
Software Centre (DMSC), in Copenhagen. A number of detector prototypes are
being developed at ESS together with its European in-kind partners, for
example: SoNDe, Multi-Grid, Multi-Blade and Gd-GEM. These are all position
sensitive detectors but use different techniques for the detection of neutrons.
Except for digitization of electronics readout, all neutron data is anticipated
to be processed in software. This provides maximum flexibility and adaptability
and allows deep inspection of the raw data for commissioning which will reduce
the risk of starting up new detector technologies. But it also requires
development of high performance software processing pipelines and optimized and
scalable processing algorithms. This report provides a description of the ESS
system architecture for the neutron data path. Special focus is on the
interface between the detectors and DMSC which is based on UDP over Ethernet
links. The report also describes the software architecture for detector data
processing and the tools we have developed, which have proven very useful for
efficient early experimentation, and can be run on a single laptop. Processing
requirements for the SoNDe, Multi-Grid, Multi-Blade and Ge-GEM detectors are
presented and compared to event processing rates archived so far.
