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Full-Text Articles in Chemistry
Collective Expansion In Central Au+Au Collisions, W. C. Hsi, G. J. Kunde, J. Pochodzalla, W. G. Lynch, M. B. Tsang, M. L. Begemann-Blaich, D. R. Bowman, R. J. Charity, F. Cosmo, A. Ferrero, C. K. Gelbke, T. Glasmacher, T. Hofmann, G. Imme, I. Iori, J. Hubele, J. Kempter, P. Kreutz, W. D. Kunze, V. Lindenstruth, M. A. Lisa, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, G. Raciti, F. Rosenberger, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidei, V. Serfling, L. G. Sobotka
Collective Expansion In Central Au+Au Collisions, W. C. Hsi, G. J. Kunde, J. Pochodzalla, W. G. Lynch, M. B. Tsang, M. L. Begemann-Blaich, D. R. Bowman, R. J. Charity, F. Cosmo, A. Ferrero, C. K. Gelbke, T. Glasmacher, T. Hofmann, G. Imme, I. Iori, J. Hubele, J. Kempter, P. Kreutz, W. D. Kunze, V. Lindenstruth, M. A. Lisa, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, G. Raciti, F. Rosenberger, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidei, V. Serfling, L. G. Sobotka
Faculty Publications
Energy spectra for intermediate mass fragments produced in central Au + Au collisions at EA=100 MeV indicate a collective expansion at breakup. For the first time, values for this collective expansion energy per nucleon are extracted independently for each charge. Typically, these values are one-third to one-half of the incident kinetic energy per nucleon in the c.m. system, but they decrease with Zf, suggesting that all fragments do not participate equally in the collective expansion.
Fragmentation Of Necklike Structures, C. P. Montoya, W. G. Lynch, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, L. Phair, M. B. Tsang, J. B. Webster, C. Williams, N. Colonna, K. Hanold, M. A. Mcmahan, G. J. Wozniak, L. G. Moretto
Fragmentation Of Necklike Structures, C. P. Montoya, W. G. Lynch, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, L. Phair, M. B. Tsang, J. B. Webster, C. Williams, N. Colonna, K. Hanold, M. A. Mcmahan, G. J. Wozniak, L. G. Moretto
Faculty Publications
Intermediate mass fragment (IMF: 3≤Z≤20 emission from necklike structures joining projectilelike and targetlike residues has been observed for peripheral Xe129 + Cunat collisions at EA=50 MeV. These fragments are emitted primarily at velocities between those of the projectilelike and targetlike residues. Relative to the charge distribution of fragments evaporated from projectilelike residues, the distribution for "neck" emission shows an enhanced emission for fragments with 4≤ZIMF≤12. This feature is consistent with expectations for the fragmentation of a noncompact cylindrical configuration.
Time Scale For Multifragmentation In Intermediate Energy Heavy-Ion Reactions, D. Fox, R. T. De Souza, T. Glasmacher, L. Phair, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu
Time Scale For Multifragmentation In Intermediate Energy Heavy-Ion Reactions, D. Fox, R. T. De Souza, T. Glasmacher, L. Phair, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu
Faculty Publications
Fragment-fragment correlations are used to probe the spatial-temporal extent of the emitting source in central Ar36+197Au reactions at E/A=35, 50, 80, and 110 MeV. The experimental two particle correlations are compared both with the Koonin-Pratt two-body formalism as well as a three-body Coulomb trajectory calculation. The spatial-temporal extent of the emitting system decreases with increasing incident energy. Within the context of a three-body Coulomb trajectory model the mean fragment emission time rises sharply as a function of the assumed density of the system until ρ/ρ0≊0.3. If one assumes a fixed density, the extracted mean emission time decreases with increasing assumed …
Semiclassical Quantization Of A Nonintegrable System: Pushing The Fourier Method Into The Chaotic Regime, Karl Sohlberg, Randall B. Shirts
Semiclassical Quantization Of A Nonintegrable System: Pushing The Fourier Method Into The Chaotic Regime, Karl Sohlberg, Randall B. Shirts
Faculty Publications
Semiclassical Einstein–Brillouin–Keller (EBK) quantization of the nonintegrable Hénon–Heiles Hamiltonian succeeds using the Fourier transform method of Martens and Ezra. Two innovations are required for this success: (1) the use of tunneling corrected quantizing actions obtained from an approximate, one-dimensional Hamiltonian and (2) exploitation of intermediate-time approximate quasiperiodicity or "vague tori'' wherein the Fourier transform of chaotic motion over 10–100 vibrational periods allows the determination of frequencies and amplitudes which approximate motion during the time interval. Approximate tori, actions, and EBK energy levels are then straightforward. We use an interpolation method to smooth over small resonance zones that are not expected …
The Structure And Dynamics Of The Cs2 Molecular Ion, Karl Sohlberg, Chan Yibai
The Structure And Dynamics Of The Cs2 Molecular Ion, Karl Sohlberg, Chan Yibai
Faculty Publications
Several common elementary methods of computing molecular properties, prerequisite to molecular dynamics studies, are tested for their validity for CS+2. Judged sufficiently accurate, these methods are then used to aid in investigating the collisionally activated dissociation of CS+2 upon impact with xenon. Rice–Ramsperger–Kassel–Marcus (RRKM) unimolecular decay rate calculations are presented and compared to experimental studies employing collisional activation. RRKM theory is shown to reproduce the experimental results for collision energies near threshold. When corrected for vibrational anharmonicity, the RRKM calculation shows agreement with the experimental results over a slightly wider range of energies. A discussion is given on the applicability …
Two-Fragment Correlation Functions With Directional Cuts For Central 36ar + 197au Collisions At E/A=50 Mev, T. Glasmacher, L. Phair, D. R. Bowman, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, R. T. De Souza, M. B. Tsang, F. Zhu
Two-Fragment Correlation Functions With Directional Cuts For Central 36ar + 197au Collisions At E/A=50 Mev, T. Glasmacher, L. Phair, D. R. Bowman, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, R. T. De Souza, M. B. Tsang, F. Zhu
Faculty Publications
Two-fragment correlation functions observed in central collisions of Ar36+197Au at E/A=50 MeV are compared to many-body trajectory calculations. For the present reaction, ambiguities between source size and lifetime can be reduced by employing directional emission cuts and describing observed differences between longitudinal and transverse correlation functions. For fragments emitted above the Coulomb barrier, E/A≥6 MeV, many-body Coulomb-trajectory calculations with a surface emission model indicate emission from an extended source of short lifetime.
Two-Proton Correlation Functions For 36ar + 45sc At E/A=80 Mev, D. O. Handzy, M. A. Lisa, C. K. Gelbke, W. Bauer, F. C. Decowski, W. G. Gong, E. Gualtieri, S. Hannuschke, R. Lacey, T. Li, W. G. Lynch, C. M. Mader, Graham F. Peaslee, T. Reposeur, S. Pratt, A. M. Vander Molen, G. D. Westfall, J. Yee, S. J. Yennello
Two-Proton Correlation Functions For 36ar + 45sc At E/A=80 Mev, D. O. Handzy, M. A. Lisa, C. K. Gelbke, W. Bauer, F. C. Decowski, W. G. Gong, E. Gualtieri, S. Hannuschke, R. Lacey, T. Li, W. G. Lynch, C. M. Mader, Graham F. Peaslee, T. Reposeur, S. Pratt, A. M. Vander Molen, G. D. Westfall, J. Yee, S. J. Yennello
Faculty Publications
Impact-parameter filtered longitudinal and transverse two-proton correlation functions measured for 36Ar+ 45Sc collisions at E/A=80 MeV are compared to predictions of the BUU transport model. For a cut on large transverse energies, the overall trends of the measured correlated functions are rather well reproduced by calculations for central collisions. Systematic discrepancies become visible, however, for calculations with larger impact parameters.
Energy Dependence Of Multifragmentation In 84kr+197au Reactions, Graham F. Peaslee, M. B. Tsang, C. Schwarz, M. J. Huang, W. S. Huang, W. C. Hsi, C. Williams, W. Bauer, D. R. Bowman, M. Chartier, J. Dinius, C. K. Gelbke, T. Glasmacher, D. O. Handzy, M. A. Lisa, W. G. Lynch, C. M. Mader, L. Phair, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, G. J. Kunde, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, G. Peilert, W. A. Friedman, N. Carlin
Energy Dependence Of Multifragmentation In 84kr+197au Reactions, Graham F. Peaslee, M. B. Tsang, C. Schwarz, M. J. Huang, W. S. Huang, W. C. Hsi, C. Williams, W. Bauer, D. R. Bowman, M. Chartier, J. Dinius, C. K. Gelbke, T. Glasmacher, D. O. Handzy, M. A. Lisa, W. G. Lynch, C. M. Mader, L. Phair, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, G. J. Kunde, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, G. Peilert, W. A. Friedman, N. Carlin
Faculty Publications
The relationship between observed intermediate mass fragment and total charged particle multiplicities has been measured for Kr84 + Au197 collisions at energies between E/A=35 and 400 MeV. Fragment multiplicities are greatest for central or near-central collisions. For these collisions, fragment production increases up to E/A≊100 MeV, and then decreases at higher energies.
Time Scale For Proton Emission From Highly Excited Projectiles, R. J. Charity, L. G. Sobotka, G. Van Buren, F. A. Tibbals, J. Barreto, D. R. Bowman, M. Chartier, J. Dinius, D. Fox, C. K. Gelbke, D. O. Handzy, W. C. Hsi, P. F. Hua, A. S. Kirov, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, D. G. Sarantites, C. Schwarz, R. T. De Souza, M. B. Tsang, C. Williams
Time Scale For Proton Emission From Highly Excited Projectiles, R. J. Charity, L. G. Sobotka, G. Van Buren, F. A. Tibbals, J. Barreto, D. R. Bowman, M. Chartier, J. Dinius, D. Fox, C. K. Gelbke, D. O. Handzy, W. C. Hsi, P. F. Hua, A. S. Kirov, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, D. G. Sarantites, C. Schwarz, R. T. De Souza, M. B. Tsang, C. Williams
Faculty Publications
Highly fragmented exit channels produced by the decay of excited 24Mg projectiles were detected. The longitudinal velocity spectra of protons and alpha particles from such channels are offset. This offset is consistent with post-breakup Coulomb accelerations from the 197Au target nuclei implying that the protons were emitted within 3 X 10−22 s after the target-projectile separation.
Electromagnetic Dissociation Of 238u At 120 Mev/A, M. L. Justice, Y. Blumenfeld, N. Colonna, D. N. Delis, G. Guarino, K. Hanold, J. C. Meng, Graham F. Peaslee, G. J. Wozniak, L. G. Moretto
Electromagnetic Dissociation Of 238u At 120 Mev/A, M. L. Justice, Y. Blumenfeld, N. Colonna, D. N. Delis, G. Guarino, K. Hanold, J. C. Meng, Graham F. Peaslee, G. J. Wozniak, L. G. Moretto
Faculty Publications
Electromagnetic fission cross sections of a 120 MeV/nucleon U238 beam incident on five targets, Be9, Al27, Cunat, Agnat, and Unat, have been extracted from measurements of projectile velocity fission fragments. The nuclear interaction contributions to the experimentally observed cross sections were determined by extrapolation from the Be target data using a geometrical scaling model and by an empirical decomposition of the fission charge distributions. The results are compared to model calculations in which electric quadrupole excitations have been included.