Development of an FPGA-based realtime DAQ system for axion haloscope experiments

TL;DR

This paper presents a custom FPGA-based real-time DAQ system for axion haloscope experiments, achieving high efficiency and improved signal-to-noise ratio in RF signal detection at very low temperatures.

Contribution

The paper introduces a novel FPGA-based DAQ system with real-time processing and high efficiency tailored for axion search experiments, outperforming commercial spectrum analyzers.

Findings

Achieved 100% data acquisition efficiency.

Demonstrated improved signal-to-noise ratio through averaging.

Validated system performance with pseudo-data analysis.

Abstract

A real-time Data Acquisition (DAQ) system for the CULTASK axion haloscope experiment was constructed and tested. The CULTASK is an experiment to search for cosmic axions using resonant cavities, to detect photons from axion conversion through the inverse Primakoff effect in a few GHz frequency range in a very high magnetic field and at an ultra low temperature. The constructed DAQ system utilizes a Field Programmable Gate Array (FPGA) for data processing and Fast Fourier Transformation. This design along with a custom Ethernet packet designed for real-time data transfer enables 100% DAQ efficiency, which is the key feature compared with a commercial spectrum analyzer. This DAQ system is optimally designed for RF signal detection in the axion experiment, with 100 Hz frequency resolution and 500 kHz analysis window. The noise level of the DAQ system averaged over 100,000 measurements is around -111.7 dBm. From a pseudo-data analysis, an improvement of the signal-to-noise ratio due to repeating and averaging the measurements using this real-time DAQ system was confirmed.