Compared to most other wavelengths, astronomy has a blind spot in the field of far-infrared radiation. Far-infrared space telescopes can only take full advantage of their sensitivity at temperatures below 4 Kelvin (-269 °C) with actively cooled mirrors. Such telescopes do not yet exist, which is why there is little worldwide investment in the development of corresponding detectors.
In 2004, SRON decided to break the cycle and invested in the development of the Kinetic Inductive Detector (KID). Now, researchers from SRON and TU Delft have achieved the highest sensitivity possible, comparable to feeling the warmth of a candle on the moon from Earth.Their research appears in Astronomy and Astrophysics September 6th.
In recent years, we have been spoiled with some of the most beautiful pictures taken by telescopes using X-ray, infrared, radio and visible light. To name a few: images of black holes in M87, Hubble’s Extreme Deep Field, or baby pictures of planetary systems. But there is one wavelength range where astronomy is relatively blind: the far infrared, especially at wavelengths between 300 microns and 10 microns.
Earth’s atmosphere blocks most radiation from ground-based telescopes, and the temperatures of space telescopes often blind their detectors from their own far-infrared radiation. With so much noise, there is little incentive to invest a lot of money in developing more sensitive far-infrared detectors. Due to the lack of sensitive detectors, the government will not allocate funds to supercooled noiseless telescopes.
In the early 2000s, SRON decided to break the mold and invest in the development of the Kinetic Inductive Detector (KID). That decision is now bearing fruit. Together with TU Delft, SRON researchers have almost perfected the technique, making it sensitive enough to see the universe’s permanent background radiation.
“Higher sensitivity is useless,” says Jochem Baselmans (SRON/TU Delft). “Because you’re always limited by the cosmic background radiation noise. So our technology gives telescope makers like NASA and ESA the most sensitive far-infrared detectors possible. We’ve seen two submissions to NASA on supercooling Proposals. Telescopes. Those are much more expensive than relatively warm telescopes, but our KID makes it worth it.”
KID helps astronomy close the terahertz gap named after the frequency of far-infrared light. Astronomers are now missing the light produced by stars in the distant young universe, leaving gaps in our knowledge of stellar evolution. Additionally, the terahertz gap is a unique opportunity for adventurous astronomers to dive into uncharted territory.
“You don’t know what you don’t know. The Hubble Deep Field is created by pointing the Hubble telescope at a dark sky where nothing appears to be in it. Then, thousands of galaxies emerge from an area smaller than the full moon. one percent,” Baselmans said.
The sensitivity the researchers achieved with their KID can be best described by a hypothetical candle on the moon. Imagine standing on Earth – or floating above the atmosphere – raising your hand to feel the warmth of the candle. Seems like a futile exercise? Not for kids. It’s even ten times more sensitive than that. The integration time is one second, and the KID can detect as small as 3*10-20 watt.
Promising far-infrared detectors could better withstand cosmic rays
JJA Baselmans et al., Ultrasensitive Ultra-THz Microwave Dynamics Inductive Detectors for Future Space Telescopes, Astronomy and Astrophysics (2022). arxiv.org/abs/2207.08647
Courtesy of SRON Netherlands Institute for Space Research
Citation: Far-Infrared Detector KID Reaches Highest Possible Sensitivity (September 6, 2022), Retrieved September 6, 2022, from https://phys.org/news/2022-09-far-infrared-detector- kid-highest-sensitivity.html
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