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Preparation of fission foils for fission ionization chambers using a painting technique

Description: Fission foils for use in fission ionization chambers were produced by painting metal substrates with coats of fissionable isotopes. Areal densities as large as 2.0 mg/cm/sup 2/ were obtained with excellent adhesion. This painting technique has been successful in depositing isotopes of uranium, plutonium, americium, and curium on metal substrates made of beryllium, aluminum, copper, and nickel. The cost of this painting technique is estimated to be approximately one-tenth the cost of producing foils by evaporation, electrodeposition, or sputtering techniques. In addition, the painting technique is highly efficient, thereby minimizing waste of the available fissionable material. (auth)
Date: November 14, 1973
Creator: Behrens, J.W.
Partner: UNT Libraries Government Documents Department

Health Physics and Safety Division annual progress report, January 1-- December 31, 1972

Description: Research topics outlined include a radiation monitoring and alarm system (Amcos II) for habitable areas of an accelerator complex; a digital environmental monitor; direct measurements of dose equivalent in aircraft; sampling and analysis of radioactive substances in the atmosphere; reactor effluents: as low as practicable or as low as reasonable, portable mixed radiation dose equivalent meter; minimizing surface dose with medium electron shields; environmental monitoring TLD studies; charcoal filter efficiency; semi-automatic film reader; radiation calibration facility; TLD extremity dosimeter; radiological assistance plan; secondary calibrator using Sr-- Y BETA 's; automation of gamma spectroscopy; nanometer energy deposition studies; nanometer dosimetry using liquid scintillators; personnel dosimetry at the AGS; expected energetic secondary neutrons missing in 200 MeV proton water shield; and Halon 1301 fire tests. (WHK)
Date: August 1, 1973
Partner: UNT Libraries Government Documents Department

Encapsulation of high-purity germanium detectors

Description: The encapsulation of high-purity germnium detectors is very desirable in order to increase their versatility and reliability. However, rapid and extensive degradation is seen for all detectors made from detector grade crystals which are encapsulated in a simple vacuum. Extensive studies have shown that the cause of this degradation is hydrogen adsorption on the detector surface. There it causes the formation of a strong p/sup +/ inversion layer which in turn shunts the detector junction. Reliable encapsulation is shown to be achievable by the use of hydrogen-free germanium crystals. (auth)
Date: June 28, 1973
Creator: Armantrout, G.A.; Wichner, R. & Swierkowski, S.P.
Partner: UNT Libraries Government Documents Department

Radiography with heavy particles

Description: The failure of x-ray diagnostic techniques to accurately detect tumors and other regions of abnormal density in soft tissue has been, for many years, a significant shortcoming of this important technique in medicine. Accelerated heavy particles with plastics for track detection can be used to record small differences in density in soft tissues which may correspond to biological structures and abnormalities. In heavy-particle radiography (HPR), plastic detectors are well suited for recording images since their threshold nature makes them insensitive to spurious low-LET radiations and light secondaries. Sources of error which limit the resolution of HPR are inversely dependent on the atomic mass number (A) of the incident particle. Range straggling, responsible for loss of depth resolution, is proportional to A$sup -$ $sub 0$ $sup 5$ while multiple scattering which degrades lateral resolution is approximately proportional to A$sup -0$.$sup 395$. Recent experiments showing calcification in human blood vessels and soft tissue features in rats underline the potential of HPR as a diagnostic tool. High-resolution, three-dimensional reconstructions are possible using multiple layer plastic detectors and the short exposure time produces blur- free radiographs of specimens whose internal structure may be in motion. (auth)
Date: August 1, 1975
Creator: Benton, E.V.; Henke, R.P.; Tobias, C.A. & Cruty, M.R.
Partner: UNT Libraries Government Documents Department

Correlation of local trapping with crystal defects by direct observation of electron loss in a coaxial Ge(Li) detector

Description: From nuclear science symposium; San Francisco, California, USA (14 Nov 1973). A propeller-shaped region of reduced full-energy-peak efficiency was observed on the face of a true coaxial Ge(Li) detector for use in a gamma camera. A similar pattern on the etch-pit photograph suggests that the propeller blades correspond to the 111 symmetry axes of the crystal. Spectra obtained when a 122 keV gamma -ray beam was directed at this degraded region, show a low energy tail which is not present when the beam is directed at normal regions. Current pulses corresponding to gamma -rays that interact in the propeller region have shapes that show deficiencies in the electron component. Thus, degraded crystal regions that are revealed by etch-pit distributions can be correlated to local detector performance by direct observation of trapping rather than only by inference from the presence of tails in the energy spectra. (auth)
Date: January 1, 1973
Creator: Strauss, M.G.; Sherman, I.S. & Bannon, R.W.
Partner: UNT Libraries Government Documents Department

Monitor for radioactive gas in the LAMPF accelerator beam channel

Description: Beam loss in accelerator structures and target areas gives rise to radioactive gases formed by interaction of secondary particles in air. A method of monitoring the air in the LAMPF accelerator beam channel using a 51.5-liter ion chamber is described. A method for control of these radioactive gases is discussed. (auth)
Date: October 1, 1973
Creator: Engelke, M.J. & Israel, H.I.
Partner: UNT Libraries Government Documents Department