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  • 1
    Electronic Resource
    Electronic Resource
    Iron solubility in highly boron-doped silicon (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1424-1426 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have directly measured the solubility of iron in high and low boron-doped silicon using instrumental neutron activation analysis. Iron solubilities were measured at 800, 900, 1000, and 1100 °C in silicon doped with either 1.5×1019 or 6.5×1014 boron atoms/cm3. We have measured a greater iron solubility in high boron-doped silicon as compared to low boron-doped silicon, however, the degree of enhancement is lower than anticipated at temperatures 〉800 °C. The decreased enhancement is explained by a shift in the iron donor energy level towards the valence band at elevated temperatures. Based on this data, we have calculated the position of the iron donor level in the silicon band gap at elevated temperatures. We incorporate the iron energy level shift in calculations of iron solubility in silicon over a wide range of temperatures and boron-doping levels, providing a means to accurately predict iron segregation between high and low boron-doped silicon. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121964
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  • 2
    Electronic Resource
    Electronic Resource
    Low-level measurement of alpha-particle emitting nuclei in ceramics and lead (1998)
    Springer
    Journal of radioanalytical and nuclear chemistry 233 (1998), S. 185-190 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Nearly all natural materials contain trace quantities of uranium (U) and thorium (Th) and their daughter nuclides, many of which emit α-particles in their decay. Lead, at the end of the U-decay chain, typically contains some radioactive210Pb which is chemically inseparable from the other Pb isotopes. α-particle emission from these decays can affect sensitive electronic components, such as memory chips or processors. Measurement of α-particle emitters can be accomplished by direct detection of the α-particles (which typically provides no positive identification of the emitting isotope because of energy loss in the sample) or by low-background γ-ray spectroscopy (which does provide positive identification via characteristic γ-rays.) The latter is by far the best method for screening kg-sized samples of materials like ceramics, aluminum, iron or copper. The difference between α counting and γ-ray spectroscopy is less for measuring210Pb in Pb since the 46.5 keV characteristic γ-rays directly following the210Pb decay are strongly absorbed and both methods are limited to thin layers. This paper discusses these two cases and concludes that a large n-type germanium γ-ray spectrometer is probably the best overall system for both measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02389669
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid detailed characterization of concrete shielding blocks utilizing internal natural radinuclides for calibration (1998)
    Springer
    Journal of radioanalytical and nuclear chemistry 233 (1998), S. 191-194 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Following many years of productive research, the 184-inch Cyclotron, the SuperHILAC, and the BEVALAC accelerators at the Berkeley Laboratory were closed, leaving thousands of concrete shielding blocks available for reuse, recycling, or disposal. The process history of these blocks precludes free release pending radiological characterization. This paper describes a procedure whereby a high efficiency shielded germanium spectrometer is used to rapidly characterize natural and man-made activity within the blocks. The spectrometer is moved up to the block and 5 minutes of data are collected at the point on the block that registers highest on a micro-R meter. Sensitivity is better than 1 pCi/g (0.037 Bq/g) for Co-60 and Eu-152, the prominent man-made activities observed. One-time calibration of the detector system is obtained from a sample of concrete, drilled with a hammer drill, counted in our low-background facility, and compared to crushed rock with known U, Th, and K activity. A simple relationship exists between the counts/minute observed in a characteristic gamma-ray peak and the activity in the block.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02389670
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of superdeformed bands in194Hg (1990)
    Springer
    The European physical journal 335 (1990), S. 325-330 
    Details
    ISSN: 1434-601X
    Keywords: 27.80.w ; 23.20.Lv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two rotational bands, with energy spacings characteristic of superdeformed shapes, have been observed following bombardment of150Nd with48Ca. The more intensively populated band consists of 18 transitions and is assigned to194Hg. The depopulation of this band occurs around spin 10. The second band, consisting of at least 16 transitions, was populated less strongly and is tentatively assigned to194Hg also. The lowest level in this band is assigned spin 8. The energy differences between transitions for both bands decrease from ∼40 keV at low rotational frequencies to ∼30 keV at the highest observed frequencies. The moments of inertia of the bands are similar to those of the two previously observed superdeformed bands in191,192Hg. The similarities and differences of the four known bands in the mercury region are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304711
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  • 5
    Electronic Resource
    Electronic Resource
    Angular momentum, statistical equilibrium and sequential fission in very asymmetric systems (1982)
    Springer
    The European physical journal 305 (1982), S. 131-134 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The in-and out-of-plane angular distributions for fission fragments in coincidence with projectile-like products from the reaction of 252 MeV20Ne with197Au and238U have been measured. The results are compared to a statistical model which has successfully explainedγ-ray anisotropies from a heavy symmetric system. The agreement is rather good after proper consideration of the direction of the line-of-centers at contact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415020
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  • 6
    Electronic Resource
    Electronic Resource
    Superdeformed bands in193Hg and194Hg (1990)
    Springer
    The European physical journal 335 (1990), S. 361-362 
    Details
    ISSN: 1434-601X
    Keywords: 23.20.Lv ; 25.70.−z ; 27.80.+w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A superdeformed band, consisting of 12 transitions, is assigned to193Hg on the basis of excitation function and cross bombardment results. A second band is identified which may be the signature partner of this band. In addition, another rotational band is observed which is assigned as the third superdeformed band in194Hg. The similarities of these three bands to those already known in the mercury region are discussed briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304716
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  • 7
    Electronic Resource
    Electronic Resource
    High-spin spectroscopy of168Hf (1987)
    Springer
    The European physical journal 327 (1987), S. 397-402 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.Re ; 23.20.Lv ; 27.70.+ q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nucleus168Hf was studied up to spin (38+) in the yrast band and to spins (41−) and (38−) in the lowest two negative-parity bands. The onset of a proton alignment (h9/2 or i13/2 quasiparticles) is observed in these three bands for the highest transitions. A new band with even spins and negative parity was found. The interaction strength between the ground-state band and theAB band is measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289564
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  • 8
    Electronic Resource
    Electronic Resource
    Use of low-background instrumental neutron activation analysis to measure contaminants in silicon and biological samples (1998)
    Springer
    Journal of radioanalytical and nuclear chemistry 234 (1998), S. 33-36 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Instrumental Neutron Activation Analysis (INAA) is a common method of trace element analysis whose sensitivity is limited either by interference from other trace elements in the sample or by interference from ambient background radiation in the detection system. In at least two cases, a true low-background facility, such as that at Lawrence Berkeley National Laboratory, substantially enhances senitivity: (1) Ultra-pure silicon, such as that used in semiconductor fabrication. Even after prolonged exposure within a nuclear reactor, minimal observable gamma-ray emitting activities are produced in the silicon. Extrapolated from our 7 gram sample size experiments, parts-per-quadrillion (1.E-15) sensitivity to 23 elements should be obtainable for 400 gram sample sizes. (2) Similarly, the life elements H, C, N, O are effectively inert within the reactor, and this enhances sensitivity to trace elements in, for example, bacteria. Data will be presented for these two cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02389743
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  • 9
    Electronic Resource
    Electronic Resource
    K-shell ionization in 7.5- and 8.6-MeV/a.m.u. U+U collisions at very small impact parameters (1986)
    Springer
    The European physical journal 2 (1986), S. 91-98 
    Details
    ISSN: 1434-6079
    Keywords: 34.50.Fa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract K-vacancy production probabilities in elastic 7.5- and 8.6-MeV/a.m.u. U+U collisions are reported for impact parameters less than 15 fm. In 7.5-MeV/a.m.u. U+U collisions the ionization probability rises above the trend indicated by larger impact parameter measurements, increasing to 1.8 vacancies per collision at the smallest impact parameter. The measured probabilities for 8.6-MeV/a.m.u. collisions increase to a maximum value of slightly less than 2 vacancies per collision at the smallest impact parameters. The data is compared to previous results and existing theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438230
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