Researchers from the National Institute of Standards and Technology, Massachusetts Institute of Technology (MIT), and the Perimeter Institute have recently established new restrictions on dark photons. These are hypothetical particles and renowned candidates for dark matter. The researchers presented their findings in a paper published by Physical Review Letters. They used a superconducting single-photon detector (SNSPD), which they invented.
Jeff Chiles, one the researchers involved in the study, said that there was a close collaboration between the research groups at NIST (MIT) and MIT (run by Dr. Sae Woonam and Prof. Karl Berggren respectively. “We collaborate to advance technology and applications of ultra-sensitive devices called superconducting single-photon detectors, or SNSPDs.
Chiles and his coworkers have been looking at potential applications for the SNSPD detectors that they have been developing over the years. They have virtually no background noise, among other advantages. They were finally introduced to theoretical physicists at the Perimeter Institute for Theoretical Physics, Canada.
Theorists from the University of California, Berkeley had an idea for a dark-matter detector that could work in a completely different area than those used in dark matter searches. Although this detector, which was a multilayer dielectric optical telescope, seemed promising, it would still require an optical detector capable of performing far better than the ones currently on the market.
Chiles stated that “This proved to be the perfect match as the MIT-NIST groups could construct the detector and apparatus and test them out.” Our project was named LAMPOST (Light-A’ Multilayer Periodic Optical SSPD Target) after the team we formed. We wanted to create an experimental proof of concept for the idea and show that it can be used to search dark matter with a higher sensitivity than the existing bounds.
Chiles and his collaborators created an optical detector based on a structure called a dielectric stack. This structure converts a nonrelativistic dark ray into a relativistic photon at the same frequency to generate signal photons.
Ilya Charaev, another researcher, said to Phys.org that they had performed an analysis of the apparatus’ construction, conducted optical simulations to calculate the detection efficiency, calculated the effect of polarization on dark matter signals and determined the minimum power that was compatible with the target properties. All incoming signals were recorded using the SNSPD technique over a 180-hour exposure.
The researchers calculated the dark count rate to limit dark matter coupling. This is also known as noise for the SNSPD detector that they created. Their noise value is, interestingly, the lowest of all reported values in physics literature.
Chiles stated that they achieved their goal because we were able scan for dark matter, specifically “dark photons”, twice as sensitively than any other energy range. Chiles stated that although this is a minor step in a vast array of dark matter possibilities, it is a significant first step. This speaks volumes about the simplicity and power of the multilayer dielectric optical telescope approach.
This team of researchers gained valuable insights that could help in future searches for dark photosns. They also encouraged the use of SNSPDs. Chiles and his coworkers learned more about the detector’s capabilities, as well as imposing new restrictions on dark photons.
They found that their detector’s noise was extremely low. The team found that they only saw 5 false events for their single-photon detectors in 180 hours of data collection. This suggests that their technology is sensitive to weak signals.
Chiles said, “It’s thrilling to imagine what other rare-event Physics experiments this technology could apply to in the near future.” “We plan to scale the experiment up from here. Although the first run was a proof of concept, the next one will be sensitive and cover a wide parameter space for dark matter. This will include dark photons as well as axions.
