Development of a superconducting bolometer
Operational superconducting bolometer for use in vacuum ultraviolet and far infrared regions
Judge, D. L.↗
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Liquid helium-cooled MOSFET preamplifier for use with astronomical bolometer
A liquid helium-cooled p-channel enhancement mode MOSFET, the 3N167, is found to have sufficiently low noise for use as a preamplifier with helium-cooled bolometers that are used in infrared astronomy. Its characteristics at 300, 77, and 4.2 K are presented. It is also shown to have useful application with certain photoconductive and photovoltaic infrared detectors.
Goebel, J. H.↗
Germanium and germanium-diamond bolometers operated at 4.2K, 2.0K, 1.2K, 0.3K and 0.1K
The design, construction, and performance of state of the art germanium and germanium-diamond bolometers operated at 4.2, 2.0, 1.2, and 0.3 K are discussed. These detectors have a broad range of applications, and are particularly important for the long wavelength (far infrared to millimeter) regions. Current results may be extrapolated to lower temperatures and higher levels of performance. A system which will operate at 0.1 K using a He-4-He-3 dilution refrigerator is under development.
Johnson, C.↗
An adiabatic demagnetization refrigerator for infrared bolometers
Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.
Britt, R. D.↗
A helium-3 cooled bolometer system for one millimeter continuum observations
A new, 1-mm-continuum, bolometer detector system has been constructed employing internal adsorption pumping of He-3 to reach an operating temperature close to 0.4 K. The system spectral bandwidth is 800 to 1200 microns. Although the system was originally designed to be used on the 5-m Hale telescope, it has also been successfully used on the 4-m Anglo-Australian telescope and on the 10-m dish at Owens Valley, California. At the 5-m Hale telescope, the system has a full width-half maximum (FWHM) beam size of 55 sec and an instantaneous noise-equivalent flux density of 6 Jy/square root of (Hz)/ in good weather.
Roellig, T. P. L.↗
Neutron-transmutation-doped germanium bolometers
Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 to the 16th and 1.88 x 10 to the 18th per sq cm. After thermal annealing the resistivity was measured down to low temperatures (less than 4.2 K) and found to follow the relationship rho = rho sub 0 exp(Delta/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2 K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers.
Palaio, N. P.↗
Cosmic-ray backgrounds in infrared bolometers
Model calculations for the production of cosmic ray events in IR detectors by energy impulses due to fast charged particles' ionization trails are presently compared to the pulse-amplitude spectrum observed from a balloon at an altitude of 38 km. The results are pertinent to the current understanding of cosmic ray backgrounds found in all high sensitivity bolometer applications. The observed signal transients are in all details consistent with the modeling of known cosmic charged particle flux characteristics and with the detector response. Generally, the optics design should minimize detector/substrate cross section.
Nolt, I. G.↗
Characterization of NTD germanium and ion-implanted Si bolometers at 0.3K and 0.1K
Bolometer elements were built and tested using NTD germanium and ion-implanted Si thermometer elements. The thermal links were made using aluminum wires and NbC(x)N(y) coated carbon fibers. The temperature dependence of the detector resistance, lead thermal conductivity, and heat capacity were measured. The dependence of the detector resistance on applied electric field was also measured. This, combined with the current-voltage curve for the detector, allowed the calculation of the detector responsivity. Known amounts of energy were deposited into the detector by allowing X-rays from the decay of Fe-55 to be thermalized in the detector. In the best-measured case, the predicted pulse height/measured height was 1.04 + or - .05. The noise at frequencies above 25 Hz in the NTD Ge was near that predicted by thermodynamics. The noise below 25 Hz has a 1/f character and may be in the carbon fiber/bolometer junction. The implanted detectors show some 1/f noise which depends on the total thermometer volume. Comparison between noise measurements and theory will be presented.
Moseley, H.↗
Interface circuitry for superconducting bolometer
The interface circuitry described links the computer with the superconducting bolometer array. This helps demonstrate the feasibility of the array. Using the circuitry and the array, imaging will be made possible. Initial imaging will be done on laboratory objects, and the pixel characteristics will be investigated experimentally.
Nelson, P. J.↗
A four channel He-3 cooled balloon-borne bolometer radiometer
A four channel He-3 cooled balloon-borne bolometer radiometer was constructed. The principal goal of the instrument is to measure the anisotropy of the 3 K cosmic background radiation on angular scales of 4 to 180 deg. The goal is to improve the sensitivity of the measurements to Delta T/T is less than .00001. A secondary goal is to survey the galactic thermal dust emission in the submillimeter range.
Meyer, Stephan↗
A 100 micro Kelvin bolometer system for SIRTF
Progress toward a prototype of 100 mK bolometric detection system for the Space Infrared Telescope Facility (SIRTF) is described. Two adiabatic demagnetization refrigerators (ADR's) were constructed and used to investigate the capabilities necessary for orbital operation. The first, a laboratory ADR, demonstrated a hold time at 0.1 K of over 12 hours, with temperature stability approx. 3 micro-K RMS achieved by controlling the magnetic field. A durable salt pill and an efficient support system have been demonstrated. A second ADR, the SIRTF flight prototype, has been built and will be flown on a balloon. Techniques for magnetic shielding, low heat leak current leads, and a mechanical heat switch are being developed in this ADR. Plans for construction of 100 mK bolometers are discussed. Three important cosmological investigations which will be carried out by these longest wavelength SIRTF detectors are described.
Bernstein, G. M.↗
Upcoming planetary missions and the applicability of high temperature superconductor bolometers
Past and present planetary exploration is briefly reviewed, and the planned 1996 Cassini mission to Saturn and Titan is examined. The CIRS experiment aboard Cassini, which will retrieve information on the atmospheres of Titan and Saturn, is discussed. Ongoing efforts to build a high-sensitivity, high-Tc bolometer that would greatly improve detection in Titan's atmosphere are addressed.
Brasunas, J.↗
Thermistor bolometer scanning radiometer - Applications and flight experience
Scanning radiometers aboard both high-altitude sun-synchronous polar orbit and low altitude equatorial orbit spacecraft have conducted measurements of the earth's long-wave radiation. Attention is presently given to the Earth Radiation Budget Satellite Experiment instruments, which are designed to measure earth radiance with an absolute radiometric error of less than 1 percent. The scanner instruments consists of three broadband radiometer channels employing thermistor bolometers as sensing elements; these radiometers repeatedly scan the earth from limb to limb every 4 sec, generating contiguous pixels on the earth's surface.
Kopia, Leonard P.↗
High-temperature-superconducting magnetic susceptibility bolometer
An infrared detector called the magnetic susceptibility bolometer is introduced which is based on the tmperature dependence of the diamagnetic screening of a high-Tc superconductor film near Tc. Results are reported for the response of a prototype model to modulated blackbody radiation. Possible improvements are discussed as is the potential sensitivity of an improved device.
Brasunas, J.↗
Design and construction of high-sensitivity, infrared bolometers for operation at 300 mK
The design and construction of 300-mK composite bolometers developed for millimeter-wave astronomical observations are described. Graphite fibers are used as the electrical leads for the thermistor to reduce the thermal conductance and heat capacity associated with the leads. A mechanical suspension made of Nylon fibers provides the required thermal conductance. Electrical noise equivalent powers below 1 x 10 exp -16 W/sq rt Hz have been achieved for detectors with thermal time constants of 11 ms. The detectors were installed in a millimeter-wave photometer and used to perform observations of the cosmic microwave background from a balloonborne platform. The flight performance was consistent with the measured laboratory properties.
Alsop, D. C.↗
YBa2Cu3O7 thin films on nanocrystalline diamond films for HTSC bolometer
Superconducting YBa2Cu3O(7-x) films on nanocrystalline diamond thin films have been fabricated. A composite buffer layer system consisting of diamond/Si3N4/YSZ/YBCO was explored for this purpose. The as-deposited YBCO films were superconducting with Tc of about 84 K and a relatively narrow transition width of about 8 K. SEM cross sections of the films showed very sharp interfaces between diamond/Si3N4 and between Si3N4/YSZ. The deposited YBCO film had a surface roughness of about 1000 A, which is suitable for high-temperature superconductive (HTSC) bolometer fabrication. It was also found that preannealing of the nanocrystalline diamond thin films at high temperature was very important for obtaining high-quality YBCO films.
Cui, G.↗
Neutron transmutation doped Ge bolometers
Some conclusions reached are as follow. Neutron Transmutation Doping (NTD) of high quality Ge single crystals provides perfect control of doping concentration and uniformity. The resistivity can be tailored to any given bolometer operating temperature down to 0.1 K and probably lower. The excellent uniformity is advantaged for detector array development.
Haller, E. E.↗
Neutron Transmutation Doped (NTD) germanium thermistors for sub-mm bolometer applications
Recent advances in the development of neutron transmutation doped (NTD) semiconductor thermistors fabricated from natural and controlled isotopic composition germanium are reported. The near ideal doping uniformity that can be achieved with the NTD process, the device simplicity of NTD Ge thermistors and the high performance of cooled junction field effect transistor preamplifiers led to the widespread acceptance of these thermal sensors in ground-based, airborne and spaceborne radio telescopes. These features made possible the development of efficient bolometer arrays.
Haller, E. E.↗