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Zabel, T.H.
Rice Univ., Houston, Tex. (USA)1976
Rice Univ., Houston, Tex. (USA)1976
AbstractAbstract
[en] The detection of characteristic x-rays using a Si(Li) detector has been investigated for the purpose of nuclear charge (Z) identification of fission fragments. Positive Z identification of one particular x-ray requires that K x-rays be used. The quantitative ambiguity due to K shell internal conversion demands that K shell vacancies be produced after nuclear excitation has relaxed. In this study, inner-shell vacancies were produced by impact ionization. The average x-ray yield for fragments stopping in a silicon surface-barrier detector was measured to be 0.018 +- 0.004 K x-rays per fragment. Similar studies using materials heavier than silicon showed a higher x-ray yield. A K x-ray Z spectrometer is proposed utilizing a germanium particle detector for x-ray production with efficiency estimated as high as 18%. However, due to nuclear straggling effects, the heavy stopping materials necessary for efficient x-ray production cannot be used as a fission fragment energy detector for a time-of-flight mass measurement of 1 amu resolution
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1976; 193 p; University Microfilms Order No. 76-21,729.; Thesis (Ph. D.).
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Report
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Thesis/Dissertation
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AbstractAbstract
[en] Over the past years, Tandem Accelerator Mass Spectrometry (TAMS) has become established as an important method for radionuclide analysis. In the Arizona system the accelerator is operated at a thermal voltage of 1.8MV for C-14 analysis, and 1.6 to 2MV for Be-10. Samples are inserted into a cesium sputter ion source in solid form. Negative ions sputtered from the target are accelerated to about 25kV, and the injection magnet selects ions of a particular mass. Ions of the 3+ charge state, having an energy of about 9MeV are selected by an electrostatic deflector, surviving ions pass through two magnets, where only ions of the desired mass-energy product are selected. The final detector is a combination ionization chamber to measure energy loss (and hence, Z), and a silicon surface-barrier detector which measures residual energy. After counting the trace iosotope for a fixed time, the injected ions are switched to the major isotope used for normalization. These ions are deflected into a Faraday cup after the first high-energy magnet. Repeated measurements of the isotope ratio of both sample and standards results in a measurement of the concentration of the radionuclide. Recent improvements in sample preparation for C-14 make preparation of high-beam current graphite targets directly from CO2 feasible. Except for some measurements of standards and backgrounds for Be-10 measurements to date have been on C-14. Although most results have been in archaeology and quaternary geology, studies have been expanded to include cosmogenic C-14 in meteorites. The data obtained so far tend to confirm the antiquity of Antarctic meteorites from the Allan Hills site. Data on three samples of Yamato meteorites gave terrestrial ages of between about 3 and 22 thousand years
Primary Subject
Source
Lunar and Planetary Inst., Houston, TX (USA); vp; 1986; vp; Workshop on cosmogenic nuclides; Los Alamos, NM (USA); 26-27 Jul 1984; Available from NTIS, PC A05/MF A01
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Report
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Conference
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AbstractAbstract
[en] A portable Faraday cup design is described for the accurate measurement of large-diameter, low-current, and high-energy proton beams traveling in air. The unit has been tested with protons from 4 to 300 MeV. The unit has an accuracy of 10% for beams of 1 pA, improving to about 2% accuracy for ion currents of 20 pA to 1 microA. For the accelerated testing of LSI parts, the Faraday cup is particularly critical, since this application requires very low currents, typically 10--100 pA (1 pA = 6 x 106 protons/s), operating in an electronically noisy accelerator environment
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Journal Article
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Esat, M.T.; Fewell, M.P.; Spear, R.H.; Zabel, T.H.
Australian National Univ., Canberra. Dept. of Nuclear Physics1981
Australian National Univ., Canberra. Dept. of Nuclear Physics1981
AbstractAbstract
[en] The static electric quadrupole moment Q2+ and the B(E2; 0+ → 2+) value of the 2+ first excited state of 204Hg have been determined using the reorientation effect in Coulomb excitation. An annular Si surface-barrier detector was used to detect backscattered 4He, 12C and 16O projectiles. In a subsidiary experiment, spectra were obtained from 204Hg(p,p') 204Hg using Si surface-barrier detectors, and the results were used in conjunction with previously existing data to povide information on higher states of 204Hg which might participate in the Coulomb excitation of the 2+ state. From a 3-level analysis, the authors find Q2+ = +0.40 +- 0.20 e.b and B(E2; 0+→ 2+) = 0.423 +- 0.0005 e2 b2. These results are in good agreement with the predictions of particle-vibrational coupling calculations. The value obtained for Q2+(204Hg) is substantially smaller in magnitude than values of Q2+ previously determined for 198200202Hg
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Source
Feb 1981; 29 p; 22 refs.
Record Type
Report
Literature Type
Numerical Data
Report Number
Country of publication
CARBON ISOTOPES, CHARGED PARTICLES, DATA, ENERGY LEVELS, ENERGY RANGE, ENERGY-LEVEL TRANSITIONS, EVEN-EVEN NUCLEI, EXCITATION, HEAVY ION REACTIONS, HEAVY NUCLEI, HELIUM IONS, INFORMATION, IONS, ISOTOPES, LIGHT NUCLEI, MERCURY ISOTOPES, MEV RANGE, NUCLEAR REACTIONS, NUCLEI, NUMERICAL DATA, OXYGEN ISOTOPES, STABLE ISOTOPES, TARGETS
Reference NumberReference Number
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Baxter, A.M.; Hinds, S.; Spear, R.H.; Zabel, T.H.; Smith, R.
Australian National Univ., Canberra. Dept. of Nuclear Physics1981
Australian National Univ., Canberra. Dept. of Nuclear Physics1981
AbstractAbstract
[en] Prominent groups are observed corresponding to excited states in the region of 2.6 MeV in the scattering of 24 and 27 MeV α-particles from 198200202204Hg and 204206208Pb. For each of the Pb isotopes the state concerned is identified with the known 3- octupole vibration. Angular distribution measurements for scattering to the Pb and 204Hg states are in agreement with octupole-vibration coupled-channels predictions, and systematic trends suggest that the states observed in the isotopes 198200202Hg can also be attributed to octupole vibrations
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May 1981; 25 p; 31 refs.
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Report
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ALPHA PARTICLES, ALPHA REACTIONS, ANGULAR DISTRIBUTION, ENERGY SPECTRA, EXCITATION, INELASTIC SCATTERING, LEAD 204, LEAD 204 TARGET, LEAD 206, LEAD 206 TARGET, LEAD 208, LEAD 208 TARGET, MERCURY 198, MERCURY 198 TARGET, MERCURY 200, MERCURY 200 TARGET, MERCURY 202, MERCURY 202 TARGET, MERCURY 204, MERCURY 204 TARGET, MEV RANGE 10-100, VIBRATIONAL STATES
ALPHA DECAY RADIOISOTOPES, CHARGED PARTICLES, DISTRIBUTION, ENERGY LEVELS, ENERGY RANGE, ENERGY-LEVEL TRANSITIONS, EVEN-EVEN NUCLEI, EXCITED STATES, HEAVY NUCLEI, HELIUM IONS, HOURS LIVING RADIOISOTOPES, IONS, ISOMERIC TRANSITION ISOTOPES, ISOTOPES, LEAD ISOTOPES, MERCURY ISOTOPES, MEV RANGE, NUCLEAR REACTIONS, NUCLEI, RADIOISOTOPES, SCATTERING, SPECTRA, STABLE ISOTOPES, TARGETS, YEARS LIVING RADIOISOTOPES
Reference NumberReference Number
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Vermeer, W.J.; Zabel, T.H.; Esat, M.T.; Kuehner, J.A.; Spear, R.H.; Baxter, A.M.
Australian National Univ., Canberra. Dept. of Nuclear Physics1982
Australian National Univ., Canberra. Dept. of Nuclear Physics1982
AbstractAbstract
[en] Coulomb excitation of the 0.718-MeV, Jsup(π) = 1+, first excited state of 10B has been studied using projectile excitation by 208Pb and observing the backward scattered particles. The results give a clear indication of the virtual excitation of the giant dipole resonance as a second-order effect. The observed magnitude is consistent with the usual hydrodynamic model estimate and with a recent shell-model calculation
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Apr 1982; 14 p; 27 refs.
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Report
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AbstractAbstract
[en] The 3 MV tandem accelerator mass spectrometer at the University of Arizona was delivered and installed by General Ionex Corporation in September, 1981. The machine was originally designed as an ultrasensitive mass spectrometer for 14C, and is in the process of being upgraded to do 36Cl and other rare isotopes as well. In this paper only the performance characteristics of the machine that relate to 14C work are discussed
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Source
Washington Univ., Seattle (USA). Nuclear Physics Lab; p. 44-53; 1982; p. 44-53; Symposium for Northeastern Accelerator personnel; Seattle, WA (USA); 6-8 Oct 1982; Available from NTIS, PC A14/MF A01; 1 as DE83011616
Record Type
Report
Literature Type
Conference; Numerical Data
Report Number
Country of publication
ACCELERATORS, AGE ESTIMATION, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, CARBON ISOTOPES, DATA, ELECTROSTATIC ACCELERATORS, ENERGY RANGE, EVEN-EVEN NUCLEI, INFORMATION, ISOTOPES, LIGHT NUCLEI, MEASURING INSTRUMENTS, MEV RANGE, NUCLEI, NUMERICAL DATA, RADIOISOTOPES, SPECTRA, SPECTROMETERS, YEARS LIVING RADIOISOTOPES
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AbstractAbstract
[en] A description is given of the tandem accelerator mass spectrometer which has recently been installed at the University of Arizona. This system is the primary instrument of a National Science Foundation Regional Instrumentation Facility. Results of tests of its operation are presented. Several experiments on archaeological and other types of samples are described. (orig.)
Primary Subject
Source
6. international conference on ion beam analysis (IBA-6); Tempe, AZ (USA); 23-27 May 1983
Record Type
Journal Article
Literature Type
Conference; Numerical Data
Journal
Nuclear Instruments and Methods in Physics Research; ISSN 0167-5087;
; v. 218(1-3); p. 425-429

Country of publication
BERYLLIUM ISOTOPES, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, CARBON ISOTOPES, CHLORINE ISOTOPES, DATA, ELECTRON CAPTURE RADIOISOTOPES, ELEMENTS, EVEN-EVEN NUCLEI, INFORMATION, ISOTOPES, LIGHT NUCLEI, NUCLEI, NUMERICAL DATA, ODD-EVEN NUCLEI, ODD-ODD NUCLEI, PHOSPHORUS ISOTOPES, POLLUTION, RADIOISOTOPES, SEMIMETALS, SPECTROSCOPY, STABLE ISOTOPES, YEARS LIVING RADIOISOTOPES
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AbstractAbstract
[en] A technique is described in which a 2 MV tandem accelerator mass spectrometer is used to detect atoms of the radioisotope 10Be. The lower detection limit is shown to be about 10Be/9Be=5x1013. Results from measurements at lower terminal voltages are also presented. (orig.)
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Record Type
Journal Article
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Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms; ISSN 0168-583X;
; v. 232(3); p. 393-395

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AbstractAbstract
[en] Results of tests on the tandem accelerator mass spectrometer (TAMS) at the University of Arizona are presented. These results demonstrate: (a) measurements of 14C/13C ratios with precisions of a few percent can be made in a period of one to several hours; (b) measurements with precisions of 0.5% have been made in which the uncertainties were mainly statistical and in which contributions to the uncertainty of machine fluctuations were negligible; (c) precise measurements of the ratio of 14C/13C in samples of N.B.S. oxalic acid and of 1890 wood are consistent with the accepted value of that ratio; (d) the real signal from a 44,000 year old sample is equal to the background rate produced from a dead carbon sample. In addition, results of some measurements on archaeological samples are presented
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Journal Article
Journal
IEEE Transactions on Nuclear Science; ISSN 0018-9499;
; v. 30(2); p. 1371-1373

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