Speaker
Description
This paper presents the development of a versatile FPGA firmware for reading out ³He resistive wire tubes used in neutron scattering experiments. 3He-base resistive wire tubes are widely used worldwide on neutron scattering instruments at both Spallation and reactor neutron sources. In fact, the main neutron sources, such as ISIS in the UK, ILL in France, SNS in the US, FRM2 in Germany, ESS in Sweden, MLF in Japan and CNCS in China, use several thousand of these detectors on their instruments.
At all these facilities, the signals from the 3He detectors are filtered and amplified by a preamp sitting close to the detector. Their output signals are digitised and further filtered on ADCs sitting up to 40m from the detectors. FPGAs on the ADC boards measure signal amplitudes, which are used to calculate the position along the detector where the neutron was absorbed.
The R5560 ADC digitises the signals at a sampling rate of 125 MHz. The firmware we developed with the SCI-Compiler software comprises two main parts: signal processing and data transmission.
In the paper, we describe the signal processing and how the user can select its features using several parameters, depending on the instrument's requirements.
The signal processing consists of a first part where offsets are removed from the analogue signals and multiplied by a constant in order to use the dynamic range of the ADC, and a second part where the signals are filtered by several walking average integrators, and a differentiator, of which the user can select the number of integrators and their lengths via several registers.
The firmware is designed to interface with multiple communication protocols, enabling seamless data streaming to various acquisition systems and a smooth transition from older to more recent, more performant ones.
We report on how, at ISIS, we are using the ADC’s serial port to transmit data to the old ISIS data acquisition system (DAE) in the most recent OSIRIS instrument application. While we also developed a fast UDP Optical Fibre data streaming system, which will be used by 2027 for the WISH instruments and, more immediately, for several uRWELLs-based detector developments.
In parallel with these two systems, an Ethernet TCP/IP system is used mainly for detector diagnostics or reliable data collection at slower speeds.
| Name of the speaker | davide raspino |
|---|---|
| Eligible for the Georges Charpak Young Scientist Award. | no |