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1.
W. Loveland K. Aleklett J. O. Liljenzin G. T. Seaborg 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(1):181-189
The use of radioanalytical techniques to study heavy ion induced nuclear reactions offers some distinct advantages over conventional physical techniques. Among these are (a) unit Z and A resultion in detecting the reaction products (b) high sensitivity for low probability events (c) lack of low energy thresholds or cutoffs in measuring reactcion product energy spectcra (d) economical use of accelerator time and (e) simple, portable experimental apparatus allowing broad survey measurements of reaction mechanisms at a variety of nuclear particle accelerators. We describe examples of these advantages from our research in nuclear chemistry. 相似文献
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W. Loveland 《Journal of Radioanalytical and Nuclear Chemistry》1993,171(1):177-181
The role of an on-site irradiation facility in nuclear science and engineering education is examined. Using the example of a university research reactor, the use of such devices in laboratory instruction, public outreach programs, special instructional programs, research, etc. is discussed. Examples from the Oregon State University curriculum in nuclear chemistry, nuclear engineering and radiation health are given. 相似文献
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H. Groening K. Aleklett K.J. Moody P.L. McGaughey W. Loveland G.T. Seaborg 《Nuclear Physics A》1982,389(1):80-92
Isomer ratios for the reaction 29Si(18O, p2n)44gSc, 44gSc have been deduced from activity measurements for projectile energies between 30 and 99 MeV. Statistical model calculations show that the isomer ratio dependence on projectile energy up to about 80 MeV can be adequately described by assuming a fixed ratio of quadrupole to dipole γ-ray strengths. Such a ratio of E2/E1 strengths agrees with corresponding values deduced from the literature. The values of the γ-ray strength ratios needed to fit the experimental isomer ratios are extremely sensitive to the relative amounts of quadrupole γ-ray admixture and to the presence of discrete levels other than those which conform to the yrast line. 相似文献
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Liang JF Shapira D Gross CJ Beene JR Bierman JD Galindo-Uribarri A Gomez del Campo J Hausladen PA Larochelle Y Loveland W Mueller PE Peterson D Radford DC Stracener DW Varner RL 《Physical review letters》2003,91(15):152701
Evaporation residue cross sections have been measured with neutron-rich radioactive 132Sn beams on 64Ni in the vicinity of the Coulomb barrier. The average beam intensity was 2 x 10(4) particles per second and the smallest cross section measured was less than 5 mb. Large sub-barrier fusion enhancement was observed. Coupled-channel calculations taking into account inelastic excitation significantly underpredict the measured cross sections below the barrier. The presence of several neutron transfer channels with large positive Q values suggests that multinucleon transfer may play an important role in enhancing the fusion of 132Sn and 64Ni. 相似文献
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W. Loveland 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(2):519-523
Radiochemistry can be an important tool in studies of nuclear reactions induced by radioactive ion beams (RIBs). RIB intensities
are typically 103–105 particles/s leading to very low reaction rates. The sensitivity of radiochemical methods and the ability to uniquely determine
the atomic properties of the reaction products offer substantial advantages. The application of radiochemical techniques to
study the fusion of 9,11Li with 70Zn and the “inverse fission” of uranium is described. 相似文献
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The temperature dependence of the drift mobility of excess charge carriers in liquid and solid hydrogen has been investigated. Both negative and positive carriers are observed in the liquid with mobilities ~ 5 × 10-3 cm2 V-1 sec-1 at 15 K; the mobile carriers in the solid are believed to be negatively Charged with a mobility ~ 6 × 10-6 cm2 V-1 sec-1 at 13 K. The mechanisms of charge localization and transport are discussed. 相似文献
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In contrast to the situation in 3, where a 2-sphere with double tangent balls at each point must be tamely embedded in 3, there exist wild (n?1)-spheres in n for n>3 with this same geometric property. However, if the sphere Σ is tame moduio a subset X that lies in a polyhedron P that is tame in Σ, the dimension of P is less than n?2, n>4, and Σ has double tangent balls over X, then Σ must be tame in n. Also if the tangent balls extend over P and are pairwise congruent, the dimensional restriction on P can be dropped. Examples are given to support the necessity of the hypotheses of the included theorems. 相似文献
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R.H. Kraus W. Loveland K. Aleklett P.L. McGaughey T.T. Sugihara G.T. Seaborg T. Lund Y. Morita E. Hagebø I.R. Haldorsen 《Nuclear Physics A》1985,432(2):525-554
Target-fragment angular distributions were measured using radiochemical techniques for 69 different fragments (44 ? A ? 196) from the interaction of 86 MeV/A12C with 197Au. The angular distributions in the laboratory system are forward-peaked with some distributions also showing a backward peaking. The shapes of the laboratory system distributions were compared with the predictions of the nuclear firestreak model. The measured angular distributions differed markedly from the predictions of the firestreak model in most cases. This discrepancy could be due, in part, to overestimation of the transferred longitudinal momentum by the firestreak model, the assumption of isotropic angular distributions for fission and particle emission in the moving frame and incorrect assumptions about how the lightest (A < 60) fragments are produced. No evidence was found for any significant number of target fragments moving sidewise to the beam direction in apparent contradiction to the expectation of hydrodynamical-model calculations. The laboratory-frame angular distributions were transformed into the moving frame using various assumptions about the moving frame velocity. The resulting light-fragment distributions showed an asymmetry in the moving frame indicative of their production in a fast process without the establishment of statistical equilibrium. No evidence was found for any production of the light fragments by a very asymmetric fission mechanism. The fission-fragment distributions were compared to standard formulas and an average fissioning-system angular momentum of was deduced. It was not possible to find a moving frame in which the heavy (A > 145) fragment distributions were symmetric about 90°. 相似文献
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K. Aleklett R. Brandt M. Bronikowski V. S. Butsev B. Chasteler G. Dersch G. Feige E. M. Friedlander E. Ganssauge G. Haase J. Herrmann D. C. Hoffman B. Judek P. Kosma B. A. Kulakov E. -J. Langrock D. Lee W. Loveland F. Pille N. T. Porile W. Schulz G. T. Seaborg 《Journal of Radioanalytical and Nuclear Chemistry》1988,122(2):355-360
In recent years the question of the unusual behavior of projectile fragments formed in the interaction of relativistic heavy ions with copper nuclei was studied using nuclear chemistry techniques. As targets we used various copper disk arrangements. It is not the intention of this conference contribution to give a complete account of the entire procedure and its results. However, we want to present a few more recent experimental findings, some of them even in a preliminary form. We want to stimulate the discussion about the entire problem which might be part of the so-called anomalon phenomenon, as observed in the field of relativistic heavy ion interactions with a few other techniques such as nuclear emulsions or bubble chambers. 相似文献