The Photonic radiation huge survive sensor is undamaged


A NIST prototype of a photonic thermometer. Credit: Jennifer Lauren Lee / NIST

Researchers at the National Institute of Standards and Technology (NIST) have published landmark tests that suggest promising classifications of high-intensity radiation environments, industrial and research applications.

The information sensors with light information are instead of electric currents in wires. They can measure, transmit and manipulate streams of photons, typically through optical fibers, and are used to gauge pressure, temperature, distance, magnetic fields, environmental conditions and more.

They are attractive because of their small size, low power consumption and environmental variables such as mechanical vibration. But the general consensus has been that high levels of radiation would modify the optical properties of their silicon, leading to incorrect readings.

So NIST, a long-time leader in photonics research, launched a program to answer those questions. The test results indicating the sensors could be customized for clinical applications and clinical radiotherapy. The results of its first round of testing are reported Nature Scientific Reports.

Specifically, the NIST results suggest the sensors used in food irradiation to destroy microbes and in medical device sterilization — estimated to be a $ 7 billion annual market in the US alone. The sensors also have potential applications in medical imaging and therapy, which together are projected to total nearly $ 50 billion in annual value worldwide by 2022.

"When we looked at publications, different labs were getting dramatically different results," said project scientist Zeeshan Ahmed, who is part of NIST's Photonic Dosimetry Project and leader of NIST's cutting-edge Photonic Thermometry Project. "That was our play motivation for doing our experiment."

"Another motivation is growing interest in deploying photonic sensors that can function accurately in very harsh environments, such as close to nuclear reactors, where radiation damage is a major concern," Ahmed said. "In addition, the space industry needs to function in high radiation environments," said project scientist Ronald Tosh. "Are they going to get damaged or not? What this study shows is that for certain classes of devices and radiation, the damage is negligible."

Photographic sensors such as the one here are transmitting information with light instead of electric currents. Recently, NIST is tested for radiation hurts these sensors' performance. In this setup, the scientists put a photonic sensor under a powerful radiation-producing electron beam. The beam travels down a shaft and hits a shutter which can be closed to the beam or opened to allow the beam through. When the beam hits the chip, it glows. From the next door control room, physicists can manipulate the beam and monitor the data telling how the chip is performing. Scientists hope to use these chips for high levels of radiation sensors, such as space used near medical imaging and cancer radiation therapy. Credit: Jennifer Lauren Lee / NIST. Music Credit: "The Messenger" by Silent Partner.

"We found that oxide-coated silicon photonic devices with radiation exposure up to 1 million gray," said Ryan Fitzgerald's leader Photonic Dosimetry project, using the SI unit for absorbed radiation. One gray represents one joule of energy absorbed by one kilogram of mass, and 1 gray corresponds to 10,000 chest X-rays. This is roughly what a sensor would receive at a nuclear power plant.

"It's the upper limit of what our calibrations customers care about," Fitzgerald said. "So the devices can be assumed to work reliably industrial or hundreds of thousands of times lower." Food irradiation, for example, a few hundred thousand gray ranges, and an amino acid that changes, the atomic properties when exposed to ionizing radiation.

The radiation from cobalt-60, a radioactive isotope. The types of sensors, small variations in their physical properties change the wavelength of light that travels through them. By measuring those changes, the devices can be used as highly sensitive thermometers or strain gauges. This remains true in extreme like space flight or nuclear reactors, only if they continue to function properly under exposure to ionizing radiation.

"Our results show that these photonic devices are robust in extreme radiation environments, which suggests they could also be used to measure radiation via its effects on physical properties of irradiated devices," Fitzgerald said. "That should come as a good news for US manufacturing, which is anxious to serve the large and growing market. in medical device sterilization and food irradiation. "

They will also be of great interest to clinical medicine, in which healthy tissues, including electrons, protons and ion beams are used. Reaching that goal demands radiation sensors with extra high sensitivity and spatial resolution. "Eventually, we hope to develop chip-scale devices for industrial materials and thus provide accurate detailed measurements," said project scientist Nikolai Klimov. A micrometer is a millionth of a meter. A human hair is about 100 micrometers wide.

The team's results have been very large for new medical therapists that employ extremely narrow beams of carbon and medical sterilization processes that use low-energy beams of electrons. "Our sensors are naturally small and chip-scale," Fitzgerald said. "Current dossiers are available for fields that vary according to those dimensions."

Can be resolved in the next stage of the research, the team will test arrays of identical conditions for small distances.

Explore further:
Hall has magnetic effects in the sensors field for high temperatures and harmful radiation environments

More information:
Zeeshan Ahmed et al, Assessing Radiation Hardness of Silicon Photonic Sensors, Scientific Reports (2018). DOI: 10.1038 / s41598-018-31286-9

Journal reference:
Scientific Reports

Provided by:
National Institute of Standards and Technology


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