To assist clarify the formation, evolution and behavior of large-scale constructions within the universe similar to galaxies, scientists have predicted the existence of darkish matter. Actually, principle means that the universe may very well include as much as 5 instances extra darkish matter than extraordinary matter! Whereas the query of what truly makes up darkish matter stays unanswered, scientists have recognized plenty of candidate particles. Among the extra promising ones are axions that could be only a ten-trillionth of the mass of an electron. In South Korea, on the Institute for Fundamental Science (IBS), they’ve assembled a staff of specialists to check and attempt to discover axions. A quick PCIe digitizer by Spectrum Instrumentation was chosen for the most recent and most superior experiments.
It’s predicted that axons will convert into photons within the presence of a powerful magnetic area. So, the Korean staff has constructed a brand new laboratory that makes use of tremendous highly effective magnets to attempt to create that exact situation. Imaging of the phenomenon is completed utilizing a haloscope, that in flip makes use of a quick information acquisition system (DAQ) to seize, analyze and retailer the outcomes.
At CAPP, the Heart for Axion and Precision Physics Analysis on the IBS, the plan is to conduct quite a lot of experiments over the approaching decade to verify the existence of axions and in the end decide their properties. The primary experimental outcomes are already in. The staff at CAPP has looked for axions with a mass between 6.62 and 6.82 μeV that correspond to the frequency between 1.6 and 1.65 GHz. The search was made utilizing the CAPP equipment proven in determine 1. The researchers confirmed experimentally with a 90% confidence stage, which is probably the most delicate end result within the mass vary up to now, that there isn’t a axion darkish matter or axion-like particle inside that vary.
A key part of the laboratory’s most not too long ago carried out information acquisition system is a Spectrum Instrumentation PCIe Digitizer card, mannequin M4i.4470-x8. The scientists selected this unit as it may well pattern the incoming alerts on two channels concurrently, at charges as much as 180 MS/s and with 16-bit vertical decision. Importantly, the collected information could be streamed to a pc, over the PCIe bus, at a switch velocity in extra of three GB/s. Which means that the entire information could be acquired and despatched to the host pc with none of it being misplaced. A block diagram of the everyday experimental setup is proven in determine 2.
Dr ByeongRok Ko, Analysis Fellow at CAPP, explains, “Our intention was to enhance the determine of benefit in axion haloscope searches, i.e., the scanning fee. First, we realized a sensible DAQ effectivity of larger than 99% for a single channel, the place the DAQ course of contains the web Quick Fourier Transforms (FFTs). Then, utilizing an IQ mixer and two parallel DAQ channels, we carried out software-based picture rejection with out shedding the DAQ effectivity. That is greater than twice the effectivity of earlier setups, which had been primarily based on utilizing a traditional spectrum analyzer.”
Picture rejection is essential as axion haloscope searches typically make use of a heterodyne receiver which introduces undesirable picture backgrounds. As such, picture rejection turns into important for sustaining a excessive scanning fee. On this case, the quick DAQ system supplies a picture rejection of about 35 dB, over a frequency vary from 600 to 2200 MHz. “There are two essential options of the Spectrum digitizer card that allow this which is why we selected it,” says Dr. ByeongRok Ko. “First, the on-board reminiscence of two GSamples, which can be utilized as a buffer, and second, a FIFO switch mode over the PCI Categorical x8 Gen2 interface, that enables the continual information streaming at speeds of larger than 3 GB/s.”
One other problem for the DAQ system is the post-processing of the information. This contains unit conversion, on-line FFT, averaging, and writing the facility spectra to disk storage. The net FFT dominates the post-processing time. Most often, axion haloscope experiments require information at totally different resonance frequencies as a result of the axion mass is unknown. Additionally, for numerous causes, the information at every resonance frequency could be divided into a number of subsets at totally different timestamps. In such instances, the post-processing could be carried out in parallel whereas the following information is being acquired. Thankfully, the Spectrum Instrumentation digitizers include drivers that assist a variety of programming languages, one in all which is Python. Python’s multiprocessing module is good for such a utility and was subsequently used to reveal the above situation.
Yannis Ok. Semertzidis, the director of CAPP and likewise a professor of KAIST (Korea Superior Institute of Science & Know-how), explains, “This experiment shouldn’t be a 100-meter dash however the first aim in a marathon run. We realized by doing it, and we examined new ideas for use at higher-level programs sooner or later.” The staff proved they’ll attain a lot better sensitivity than all different experiments beforehand accomplished over the goal frequency vary. The plan now’s to scale up their experiments with bigger programs.
