Researchers from the National Institute of Standards and Technology (NIST), the Massachusetts Institute of Technology (MIT), and the Perimeter Institute have recently established new constraints on dark photons, which are hypothetical particles and well-known candidates for dark matter. Their findings, presented in an article published in Physical examination letterswere achieved using a novel superconducting nanowire single photon detector (SNSPD) they developed.
“There is close collaboration between our research groups at NIST and MIT, led by Dr. Sae Woo Nam and Professor Karl Berggren, respectively,” Jeff Chiles, one of the researchers who conducted the study, told Phys.org. “We are working together to advance the technology and applications of ultra-sensitive devices called Superconducting Nanowire Single Photon Detectors, or SNSPDs.”
Over the past few years, Chiles and his colleagues have considered potential applications that would benefit from the SNSPD detectors they have been working on, which have virtually no background noise among other advantageous characteristics. They were eventually presented to a group of theoretical physicists from the Perimeter Institute for Theoretical Physics in Canada.
This team of theorists came up with an interesting idea for a dark matter detector that could work in an entirely different field than those currently used in dark matter searches. This detector, namely a multilayer dielectric optical haloscope, was a very promising concept, but it would require an optical detector that could perform much better than those on the market today.
“It turned out to be the perfect combination, because the MIT and NIST groups were able to build the detector and the device and test them,” Chiles explained. “So we teamed up and called our project LAMPOST (Light A’ Multilayer Periodic Optical SNSPD Target). Our goal was to achieve the first experimental proof of concept for this idea and to prove that it could be used to search for dark matter with better sensitivity than the limits already established.”
The optical detector designed by Chiles and his colleagues is based on a structure known as a stack or dielectric target. This structure can generate signal photons of interest, by converting a non-relativistic dark photon into a relativistic photon at the same frequency.
“First, we performed analysis of device construction, optical simulations to determine optical collection efficiency, simulation of detection efficiency, calculation of polarization influence on the dark matter signal and the minimum signal strength compatible with the possible range of target properties,” Ilya Charaev, another researcher involved in the study, told Phys.org. “Using the SNSPD technique, all incoming signals were recorded over a 180 hour exposure.”
To set a limit on dark matter coupling, the researchers estimated the count rate in the dark, also called “noise” for the SNSPD detector they developed. Interestingly, their estimated noise value is the lowest among all values reported in the physical literature.
“Notably, we achieved our goal because we were able to search for a type of dark matter, specifically ‘dark photons’, that were twice as sensitive as anything else in the energy range we searched for,” said Chiles. “In the grand scheme of things, this is still just a small notch on a huge range of possibilities for dark matter. But for our first run, pushing past the existing limits is an important first step, and for me , this demonstrates the power and simplicity of the multilayer dielectric optical haloscope approach.”
In their experiments, this team of researchers gathered valuable insights that could inform future dark photon searches, while potentially encouraging the use of SNSPDs. In addition to establishing new constraints on dark photons, Chiles and his colleagues learned more about the capabilities of their detector.
Most notably, they found that the noise in their detector was incredibly low. Specifically, the team only observed 5 “false events” for one of their single-photon detectors over 180 hours of data collection, suggesting that their technology is very sensitive to weak signals.
“It’s exciting to think about what other rare event physics experiments this technology could be applied to in the near future,” Chiles added. “In the meantime, we plan to extend the experiment from here. The first run was a proof of concept, but the next one will be sensitive enough to cover a large parameter space for dark matter, which will include both black axions and photons.”
Gravitational wave detectors to search for dark matter
Jeff Chiles et al, New Constraints on Dark Photon Dark Matter with Superconducting Nanowire Detectors in an Optical Haloscope, Physical examination letters (2022). DOI: 10.1103/PhysRevLett.128.231802
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Quote: Study Defines New Constraints on Dark Photons Using New Dielectric Optical Haloscope (July 6, 2022) Retrieved July 8, 2022 from https://phys.org/news/2022-07-constraints-dark -photons-dielectric-optical.html
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