  The neutron detection system for characterization of emissivity in ITER
Tokamak during DD and DT experiments poses serious challenges to the
performance of the diagnostic control and data acquisition system (CDAcq). The
ongoing design of the ITER Radial Neutron Camera (RNC) diagnostic is composed
by 26 lines of sight (LOS) for complete plasma inspection. The CDAcq system
aims at meeting the ITER requirements of delivering the measurement of the
real-time neutron emissivity profile with time resolution and control cycle
time of 10 ms at peak event rate of 2 MEvents/s per LOS. This measurement
demands the generation of the neutron spectra for each LOS with neutron/gamma
discrimination and pile up rejection. The neutron spectra can be totally
processed in the host CPU or it can use the processed data coming from the
system FPGA. The number of neutron counts extracted from the spectra is then
used to calculate the neutron emissivity profile using an inversion algorithm.
Moreover, it is required that the event based raw data acquired is made
available to the ITER data network without local data storage for post
processing. The data production for the 2 MEvents/s rate can go up to a maximum
data throughput of 0.5 GB/s per channel. The evaluation of the use of real-time
data compression techniques in RNC is also depicted in another contribution.
  To meet the demands of the project a CDAcq prototype has been used to design
and test a high-performance distributed software architecture taking advantage
of multi-core CPU technology capable of coping with the requirements. This
submission depicts the design of the real-time architecture, the spectra
algorithms (pulse height analysis, neutron/gamma discrimination and pile-up
correction) and the inversion algorithm to calculate the emissivity profile.
Preliminary tests to evaluate the system performance with synthetic data are
presented.
