A document proposes the development of hot-electron photon counters (HEPCs) for detecting terahertz photons in spaceborne far-infrared astronomical instruments. These would be superconducting-transition-edge devices: they would contain superconducting bridges that would have such low heat capacities that single terahertz photons would cause transient increases in their electron temperatures through the superconducting-transition range, thereby yielding measurable increases in electrical resistance. Single devices or imaging arrays of the devices would be fabricated as submicron-sized bridges made from films of disordered Ti (which has a superconducting-transition temperature of ≈0.35 K) between Nb contacts on bulk silicon or sapphire substrates. In operation, these devices would be cooled to a temperature of ≈0.3 K. The proposed devices would cost less to fabricate and operate, relative to integrating bolometers of equal sensitivity, which must be operated at a temperature of ≈0.1 K.
This work was done by Boris Karasik of Caltech and Andrei Sergeyev of Wayne State University for NASA’s Jet Propulsion Laboratory. NPO-40660
This Brief includes a Technical Support Package (TSP).
Hot-Electron Photon Counters for Detecting Terahertz Photons
(reference NPO-40660) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory, focusing on Hot-Electron Photon Counters (HEPC) designed for detecting terahertz (THz) photons. It outlines the significance of these detectors in low-background applications, particularly in space THz astronomy, where current technology is lacking. The HEPC is proposed as a promising solution to meet the sensitivity requirements for detecting THz radiation while operating at cryogenic temperatures (around 0.3 K).
The document discusses the challenges associated with achieving a combination of low noise equivalent power (NEP) and long time constants in photon counting modes for THz radiation. It emphasizes that superconducting Transition Edge Sensor (TES) bolometric photon counters have been successfully developed for various wavelengths, from X-ray to near-infrared, and highlights their advantages, including robust thin-film technology and compatibility with low-noise superconducting quantum interference device (SQUID) readouts.
Key features of the HEPC include its ability to achieve high energy resolution without the need for external wavelength dispersing elements, thanks to negative electro-thermal feedback mechanisms. The document also mentions the importance of maintaining a low dark count rate, which is crucial for the performance of the detector. It notes that the limited speed of the device is a key factor in keeping the dark count rate low, which is essential for effective photon counting.
Additionally, the document references various studies and publications that provide further insights into the technology and its applications. It highlights the potential of HEPCs not only for astronomical applications but also for laboratory molecular spectroscopy, quantum information applications, and the study of nanoscale thermal processes.
In conclusion, the Technical Support Package serves as a comprehensive overview of the HEPC technology, its development, and its potential applications in both space and laboratory settings. It underscores the importance of advancing THz photon detection technology to enhance scientific research and exploration in various fields. The document also provides contact information for further assistance and resources related to NASA's aerospace-related developments.
