Study sets new limits on dark photons using a new dielectric optical haloscope

Researchers at the National Institute of Standards and Technology (NIST), the Massachusetts Institute of Technology (MIT) and the Perimeter Institute recently set new limits on dark photons, which are hypothetical particles and known dark matter candidates. Their findings, presented in a paper published in Physical Assessment Letterswere achieved using a new superconducting nanowire single-photon detector (SNSPD) they developed.

“There is a close collaboration between our research groups at NIST and MIT, led by Dr. Sae Woo Nam and Prof. 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 for ultra-sensitive devices called superconducting nanowire single-photon detectors or SNSPDs.”

In recent years, Chiles and his colleagues have considered possible applications that could benefit from the SNSPD detectors they have been working on, which have virtually no background noise among other beneficial features. They were eventually introduced to a group of theoretical physicists at the Perimeter Institute for Theoretical Physics in Canada.

This team of theorists had an interesting idea for a dark matter detector that could operate in a very different domain from those currently used in the search for dark matter. This detector, namely a multilayer dielectric optical haloscope, was a promising concept, but it would require an optical detector that could perform much better than the detectors currently on the market.

“This turned out to be the perfect match, as the MIT and NIST groups were able to build and test the detector and device,” Chiles explained. So we teamed up and named 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 prove that it can be used to get to dark matter. to seek with greater sensitivity than the limits already established.”

The optical detector devised by Chiles and his colleagues is based on a structure known as a dielectric stack or target. This structure can generate signal photons of interest by converting a non-relativistic dark photon into a relativistic photon of the same frequency.

“First, we performed an analysis of the device construction, optical simulations to determine the optical collection efficiency, simulation of the detection efficiency, calculation of the influence of polarization on the dark matter signal and the minimum signal power 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 put a limit on the dark matter coupling, the researchers estimated the dark count rate, also called “noise” for the SNSPD detector they developed. Interestingly, their estimated noise value is the lowest of all values ​​reported in the physics literature.

“Notably, we succeeded in our goal because we were able to scan for a type of dark matter, specifically ‘dark photons,’ twice as sensitive as anything else in the energy range we were looking for,” Chiles said. “In the grand scheme of things, this is still one small step out of a huge range of possibilities for dark matter† But for our first run to cross existing boundaries is an important first step, and to me this speaks to 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 searches for dark photons, while also potentially encouraging the use of SNSPDs. In addition to putting new restrictions on dark photons, Chiles and his colleagues learned more about their detector’s capabilities.

Most notably, they found that the sound in their detector was incredibly low. More specifically, the team observed only 5 “false events” for one of their single-photon detectors over 180 hours of data collection, suggesting that their technology is highly 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 scale up the experiment from here. The first run was a proof-of-concept, but the next one will be sensitive enough to allow for a large parameter space for dark matterwhich will contain both axions and dark photons.”

© 2022 Science X Network