[en] A comparison has been made between the production of high energy (E_γ≥30 MeV) γ rays from the bombardment of ¹²⁴Sn and ¹¹²Sn targets with E/A=10 MeV ¹²C ions. The results are well explained by the n-p bremsstrahlung model and do not indicate the need for any new processes. (orig.)

[en] The distribution of β⁺ Gamow-Teller strength in ²⁶Mg, ⁵⁴Fe and ⁵⁶Ni is calculated in the QRPA and large-basis shell-model spaces. The quenching relative to the simplest jj coupled model found in the QRPA is similar to that found in a shell-model basis which includes 2p2h ground-state correlations within the major shell (sd or pf). For ²⁶Mg there is significant additional quenching found in the full sd shell-model space relative to the 2p2h model space. We explore the connection between this additional quenching and the transition from jj to SU(3) LS coupling via its relationship to the quadrupole collectivity. From this analysis we are able to estimate the total β⁺ strength in ⁵⁴Fe and and ⁵⁶Ni which would be obtained in the full pf shell-model space. These calculations, together with the global quenching factor of 0.6, account for the observed strength in these nuclei. The quenching effects appearing in heavier nuclei are discussed. (orig.)

[en] The results of design studies of the central region for a proposed superconducting cyclotron for advanced cancer therapy are presented here. The studies considered a four sector cyclotron operating in the second harmonic (h=2) acceleration mode capable of producing 250 MeV protons. The studies were based on detailed beam orbit calculations and the results presented here cover design considerations on the basis of beam centering, vertical focusing, and with an emphasis on phase selection. ((orig.))

[en] Radioactive ion beams are rapidly becoming an important new tool in nuclear science research. A number of facilities have been built or are under construction worldwide which will allow separation of relatively pure radioactive ion beams. A number of these facilities, including LISE at GANIL, RIPS at RIKEN, the FRS at GSI, and the A1200 at the NSCL, are based on the separation of projectile-like fragments using a doubly achromatic system. As part of the work leading up to experiments using the A1200, we have developed a computer code which allows fast, interactive estimation of secondary ion beam intensities and purities for use in the design and interpretation of experiments. The code has been designed to model and doubly achromatic device of design similar to the A1200 by using an idealized initial secondary beam from a production target. The various atomic effects involving the interaction of ion beams with targets and degraders, including the equilibrium charge states of beams leaving these materials, have been analyzed in detail and incorporated into the program. An analytical description of the beam transport system using first order beam optics has been developed. A comparison between the program and various other simulation methods as well as measured production rates have shown good agreement. (orig.)

[en] Physics aspects of the energetic heavy-ions reactions, including changes in the bulk properties of matter during reactions and features of transport description, are discussed. Observables such as particle correlations, mean momentum in the reaction plane, light-fragment yields and spectra are reviewed, together with the information these observables provide on size of the emission region, magnitude of nuclear compressibility, production of entropy, and energy of collective expansion. (author). 25 refs, 9 figs

[en] Recent advances in computed tomography provide measurement tools to study internal structures of soil aggregates at micrometer resolutions and to improve our understanding of specific mechanisms of various soil processes. Fractal analysis is one of the data analysis tools that can be helpful in evaluating heterogeneity of the intra-aggregate internal structures. The goal of this study was to examine how long-term tillage and land use differences affect intra-aggregate pore heterogeneity. The specific objectives were: (i) to develop an approach to enhance utility of box-counting fractal dimension in characterizing intra-aggregate pore heterogeneity; (ii) to examine intra-aggregate pores in macro-aggregates (4-6 mm in size) using the computed tomography scanning and fractal analysis, and (iii) to compare heterogeneity of intra-aggregate pore space in aggregates from loamy Alfisol soil subjected to 20 yr of contrasting management practices, namely, conventional tillage (chisel plow) (CT), no-till (NT), and native succession vegetation (NS). Three-dimensional images of the intact aggregates were obtained with a resolution of 14.6 (micro)m at the Advanced Photon Source, Argonne National Laboratory, Argonne, IL. Proposed box-counting fractal dimension normalization was successfully implemented to estimate heterogeneity of pore voxel distributions without bias associated with different porosities in soil aggregates. The aggregates from all three studied treatments had higher porosity associated with large (>100 (micro)m) pores present in their centers than in their exteriors. Pores 15 to 60 (micro)m were equally abundant throughout entire aggregates but their distributions were more heterogeneous in aggregate interiors. The CT aggregates had greater numbers of pores 15 to 60 (micro)m than NT and NS. Distribution of pore voxels belonging to large pores was most heterogeneous in the aggregates from NS, followed by NT and by CT. This result was consistent with presence of very large pores associated with former root channels in NT and NS aggregates. Our findings indicate that mechanisms of macro-aggregate formation might differ in their importance in different land use and management practices.

[en] Current industrial program development practice is reviewed and its relevance to high energy physics is discussed. The experience of DO with these techniques is commented on, and a selected bibliography provided

[en] Deterministic chaos with its nonlinearities can formally reproduce some of the counterintuitive idiosyncrasies of quantum mechanics. In this paper I raise the question as to whether chaos might possibly supply some of the ''hidden variables'' that have been sought as underpinnings at a deeper level of quantum mechanics. (orig.)

[en] Simple and exotic radiochemical techniques used for the separation purification and analysis of neutron-deficient short-lived nuclides are reviewed. These range from classical wet-chemical methods to automated and instrumental techniques. Special attention is given to chemical adjuncts of the He-jet recoil-transport technique and to high-resolution mass spectrometry. Recent developments in biological applications, including ¹³N production and use are overviewed. (author) 38 refs.; 10 figs

[en] Facets of collective expansion in central energetic heavy-ion collisions are studied within a transport model. The expansion significantly affects the angular distributions and spectra of emitted baryons. The distributions peak at 90 in the c.m. polar angle at the lowest impact parameters. The mean energies of baryons emitted at 90 in the center of mass, rise with the baryon mass due to a collective contribution to these energies. Pion yields from the collisions are significantly depressed by the expansion, while cluster yields are enhanced. (orig.)