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Full-Text Articles in Physical Sciences and Mathematics
Peroxyl Radical Clocks, Bill Roschek, Keri A. Tallman, Christopher L. Rector, Jason G. Gillmore, Derek A. Pratt, Carlo Punta, Ned A. Porter
Peroxyl Radical Clocks, Bill Roschek, Keri A. Tallman, Christopher L. Rector, Jason G. Gillmore, Derek A. Pratt, Carlo Punta, Ned A. Porter
Faculty Publications
A series of peroxyl radical clocks has been developed and calibrated based on the competition between the unimolecular β-fragmentation (kβ) of a peroxyl radical and its bimolecular reaction with a hydrogen atom donor (kH). These clocks are based on either methyl linoleate or allylbenzene and were calibrated directly with α-tocopherol or methyl linoleate, which have well-established rate constants for reaction with peroxyl radicals (kH-tocopherol = 3.5 × 106 M-1 s-1, kH-linoleate = 62 M-1 s-1). This peroxyl radical clock methodology has been successfully applied to determine inhibition and propagation rate constants ranging from 100 to 107 M-1 s-1.
Isobaric Analog States As A Tool For Spectroscopy Of Exotic Nuclei, G. V. Rogachev, A. A. Aprahamian, F. D. Becchetti, P. Boutachkov, Y. Chen, G. Chubarian, P. A. Deyoung, A. Fomichev, V. Z. Goldberg, M. S. Golovkov, J. J. Kolata, Yu. Ts. Oganessian, Graham F. Peaslee, M. Quinn, A. Rodin, B. B. Skorodumov, R. S. Slepnev, G. Ter-Akopian, W. H. Trzaska, A. Wohr, R. Wolski
Isobaric Analog States As A Tool For Spectroscopy Of Exotic Nuclei, G. V. Rogachev, A. A. Aprahamian, F. D. Becchetti, P. Boutachkov, Y. Chen, G. Chubarian, P. A. Deyoung, A. Fomichev, V. Z. Goldberg, M. S. Golovkov, J. J. Kolata, Yu. Ts. Oganessian, Graham F. Peaslee, M. Quinn, A. Rodin, B. B. Skorodumov, R. S. Slepnev, G. Ter-Akopian, W. H. Trzaska, A. Wohr, R. Wolski
Faculty Publications
Spectroscopy of neutron rich exotic isotopes via their isobaric analog states (IAS) in less exotic nuclei is discussed. Several different experimental techniques, which can be applied to search for IAS of exotic isotopes, are described. Successful application of these techniques to the studies of heavy helium isotopes7He and 9He led to the observation of unknown IAS in 7Li and 9Li. Spectroscopic information for these states were obtained, and implication of these findings to the structure of 7,9He is considered.
Quantum Amplified Isomerization: A New Concept For Polymeric Optical Materials, Jason G. Gillmore, J. D. Neiser, K. A. Mcmanus, Y. Roh, G. W. Dombrowski, T. G. Brown, J. P. Dinnocenzo, S. Farid, D. R. Robello
Quantum Amplified Isomerization: A New Concept For Polymeric Optical Materials, Jason G. Gillmore, J. D. Neiser, K. A. Mcmanus, Y. Roh, G. W. Dombrowski, T. G. Brown, J. P. Dinnocenzo, S. Farid, D. R. Robello
Faculty Publications
The preparation and evaluation of a new class of photoresponsive polymers are described on the basis of a process called quantum amplified isomerization (QAI). The QAI process utilizes photoinitiated, cation radical isomerization chemistry in a polymeric medium. Two classes of materials are described: one where the QAI reactant is molecularly doped in the polymer matrix and another where the reactant is part of a functionalized polymer. Quantum yield experiments demonstrate that the isomerization reaction can proceed by a chain process with modest efficiencies. Photochemical conversion experiments show that high extents of conversion of the QAI reactants are possible. The rate …
A-Stripping Reactions With Exotic Nuclei: 12c7be,3he)16o, H. Amro, F. D. Becchetti, Yu Chen, H. Jiang, M. Ojaruega, H. C. Griffin, J. J. Kolata, B. B. Skorodumov, J. D. Hinnefeld, Graham F. Peaslee
A-Stripping Reactions With Exotic Nuclei: 12c7be,3he)16o, H. Amro, F. D. Becchetti, Yu Chen, H. Jiang, M. Ojaruega, H. C. Griffin, J. J. Kolata, B. B. Skorodumov, J. D. Hinnefeld, Graham F. Peaslee
Faculty Publications
The 12C(7Be,3He)16O reaction has been studied at E(7Be)=34 MeV. At this energy this Reaction exhibits a high selectivity for populating known α‐cluster states in 16O (Jπ = 0+,3−,2+,1−,4+, and 6+). The angular distributions for the 0+,3−,2+,1−, and 4+ levels are obtained at forward angles. Likewise, large reaction rates were measured for the 3He transfer channel, i.e. 12C(7Be,α)15O
Doppler Shift As A Tool For Studies Of Resonant (P,N) Reactions With Ribs: Spectroscopy Of 7he, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wöhr
Doppler Shift As A Tool For Studies Of Resonant (P,N) Reactions With Ribs: Spectroscopy Of 7he, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wöhr
Faculty Publications
We report on a new methods for studies of neutron rich systems through resonant (p,n) reaction with radioactive ion beams. A specific example of the spectroscopy of 7He and future application of the proposed methods are discussed.
Cyclopropylcarbinyl → Homoallyl-Type Ring Opening Of Ketyl Radical Anions. Structure/Reactivity Relationships And The Contribution Of Solvent/Counterion Reorganization To The Intrinsic Barrier, J. M. Tanko, Jason G. Gillmore, Robert Friedline, M'Hamed Chahma
Cyclopropylcarbinyl → Homoallyl-Type Ring Opening Of Ketyl Radical Anions. Structure/Reactivity Relationships And The Contribution Of Solvent/Counterion Reorganization To The Intrinsic Barrier, J. M. Tanko, Jason G. Gillmore, Robert Friedline, M'Hamed Chahma
Faculty Publications
Following a protocol developed by Mathivanan, Johnston, and Wayner (J. Phys. Chem. 1995, 99, 8190−8195), the radical anions of several cyclopropyl- and oxiranyl-containing carbonyl compounds were generated in an effort to measure the rate constants for their ring opening (ko) by laser flash photolysis. The results of these experiments are compared to those obtained from earlier electrochemical studies, and the combined data set is used to rationalize the kinetics of radical anion ring opening in a general context by using Savéant's theory pertaining to stepwise dissociative electron transfer (Acc. Chem. Res. 1993, 26, 455−461). Compared to cyclopropylcarbinyl → homoallyl rearrangements …
Two-Neutron Transfer In The 6he + 209bi Reaction Near The Coulomb Barrier, Paul A. Deyoung, Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy, H. Griffin, C. Guess, J. D. Hinnefeld, H. Jiang, Scott R. Jones, U. Khadka, D. Lizcano, E. Martinez-Quiroz, M. Ojaniega, Graham F. Peaslee, A. Pena, J. Reith, S. Vandendriessche, J. A. Zimmerman
Two-Neutron Transfer In The 6he + 209bi Reaction Near The Coulomb Barrier, Paul A. Deyoung, Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy, H. Griffin, C. Guess, J. D. Hinnefeld, H. Jiang, Scott R. Jones, U. Khadka, D. Lizcano, E. Martinez-Quiroz, M. Ojaniega, Graham F. Peaslee, A. Pena, J. Reith, S. Vandendriessche, J. A. Zimmerman
Faculty Publications
The cross section for α-particle emission in the He6+Bi209 reaction at energies near the Coulomb barrier is remarkably large. Possible reactions that may produce the observed α particles include two-neutron transfer, one-neutron transfer, and direct projectile breakup. Each of these mechanisms results in a distinctive angular correlation between the α particle and the outgoing neutron(s). A neutron-α-particle coincidence experiment was performed to study two-neutron transfer to unbound states of Bi211. It is shown that approximately 55% of the observed α-particle yield at and beyond the grazing angle is because of this process. This is more than 2.5 times the fraction …
Isobaric Analog States Of Neutron-Rich Nuclei. Doppler Shift As A Measurement Tool For Resonance Excitation Functions, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wohr
Isobaric Analog States Of Neutron-Rich Nuclei. Doppler Shift As A Measurement Tool For Resonance Excitation Functions, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wohr
Faculty Publications
We present a new approach for the measurement of resonance excitation functions of neutron-rich nuclei using Doppler shift information. Preliminary data from the first application of the method is presented in the spectroscopy studies of 7He isobaric analog states in 7Li.
Quantum Amplified Isomerization: A New Chemically Amplified Imaging System In Solid Polymers, Douglas R. Robello, Joseph P. Dinnocenzo, Samir Farid, Jason G. Gillmore, Samuel W. Thomas Iii
Quantum Amplified Isomerization: A New Chemically Amplified Imaging System In Solid Polymers, Douglas R. Robello, Joseph P. Dinnocenzo, Samir Farid, Jason G. Gillmore, Samuel W. Thomas Iii
Faculty Publications
A new imaging system based on a photoinitiated electron transfer chain reaction is reported. Specifically, irradiation of 9,10-dicyanoanthracene (sensitizer) leads to the conversion of Dewar benzene derivatives (reactants) to benzene derivatives (products) within solid polymer films. The mechanism of the reaction may involve chemical amplification with cation radicals ("holes") as the catalytic species. We present herein studies of both molecularly doped polymers and polymers containing Dewar benzene moieties attached to side chains. The refractive index of the materials could be tuned within a narrow range using this photochemical reaction, as demonstrated by the writing of persistent gratings in forced Rayleigh …
A High Throughput Method For The Conversion Of Co2 Obtained From Biochemical Samples To Graphite In Septa-Sealed Vials For Quantification Of 14c Samples Via Accelerator Mass Spectrometry, Ted J. Ognibene, Graham Bench, John S. Vogel, Graham F. Peaslee, Steve Murov
A High Throughput Method For The Conversion Of Co2 Obtained From Biochemical Samples To Graphite In Septa-Sealed Vials For Quantification Of 14c Samples Via Accelerator Mass Spectrometry, Ted J. Ognibene, Graham Bench, John S. Vogel, Graham F. Peaslee, Steve Murov
Faculty Publications
The growth of accelerator mass spectrometry as a tool for quantitative isotope ratio analysis in the biosciences necessitates high-throughput sample preparation. A method has been developed to convert CO2 obtained from carbonaceous samples to solid graphite for highly sensitive and precise 14C quantification. Septa-sealed vials are used along with commercially available disposable materials, eliminating sample cross contamination, minimizing complex handling, and keeping per sample costs low. Samples containing between 0.25 and 10 mg of total carbon can be reduced to graphite in 4 h in routine operation. Approximately 150 samples per 8-h day can be prepared by a single technician.
A New Accelerator Mass Spectrometry System For 14c-Quantification Of Biochemical Samples, Ted J. Ognibene, Graham Bench, Tom A. Brown, Graham F. Peaslee, John S. Vogel
A New Accelerator Mass Spectrometry System For 14c-Quantification Of Biochemical Samples, Ted J. Ognibene, Graham Bench, Tom A. Brown, Graham F. Peaslee, John S. Vogel
Faculty Publications
A compact accelerator mass spectrometry (AMS) system that meets our requirements for View the MathML source-quantification of biochemical samples is described. The spectrometer occupies approximately 5 m2 of floor space and can measure >300 samples per day with 3% precision. A long diffuse gas cell is used to destroy interfering molecules and to charge exchange injected negative ions. System sensitivity is <1 amol View the MathML source/mg carbon on milligram-sized samples with a dynamic range that extends over 4 orders magnitude. All components, with the exception of the ion source, are commercially available and the system operates reliably with low maintenance.
A Statistical Interpretation Of The Correlation Between Imf Multiplicity And Transverse Energy, L. Phair, L. Beaulieu, L. G. Moretto, G. J. Wozniak, D. R. Bowman, N. Carlin, L. Celano, N. Colonna, J. D. Dinius, A. Ferrero, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, W. C. Hsi, M. J. Huang, I. Iori, Y. D. Kim, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, P. F. Mastinu, P. M. Milazzo, C. P. Montoya, A. Moroni, Graham F. Peaslee, R. Rui, C. Schwarz, M. B. Tsang, K. Tso, G. Vannini, F. Zhu
A Statistical Interpretation Of The Correlation Between Imf Multiplicity And Transverse Energy, L. Phair, L. Beaulieu, L. G. Moretto, G. J. Wozniak, D. R. Bowman, N. Carlin, L. Celano, N. Colonna, J. D. Dinius, A. Ferrero, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, W. C. Hsi, M. J. Huang, I. Iori, Y. D. Kim, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, P. F. Mastinu, P. M. Milazzo, C. P. Montoya, A. Moroni, Graham F. Peaslee, R. Rui, C. Schwarz, M. B. Tsang, K. Tso, G. Vannini, F. Zhu
Faculty Publications
Multifragment emission following 129Xe+197Au collisions at 30A, 40A, 50A, and 60A MeV has been studied with multidetector systems covering nearly 4π in solid angle. The correlations of both the intermediate mass fragment and light charged particle multiplicities with the transverse energy are explored. A comparison is made with results from a similar system 136Xe+209Bi at 28A MeV. The experimental trends are compared to statistical model predictions.
The Benign Hamburger, Graham F. Peaslee, Juliette Lantz, Mary Walczak
The Benign Hamburger, Graham F. Peaslee, Juliette Lantz, Mary Walczak
Faculty Publications
In this dilemma case study, the executives of a popular restaurant chain must decide whether to use irradiated meat, in this case, beef, to protect its customers from the bacteria, E. coli. Students learn about food irradiation and discuss issues related to food safety and the public’s acceptance of new food technologies. As developed, the case could be used in a variety of introductory science courses in chemistry, physics, biology, environmental science, and agricultural science.
A Comparison Between Pixe Studies And Electron Microprobe Studies Of Rocks From Southern India., Graham F. Peaslee, D. A. Carlson, E. C. Hansen, S. S. Hendrickson, R. J. Timmer, A. L. Van Wyngarden, J. D. Wilcox
A Comparison Between Pixe Studies And Electron Microprobe Studies Of Rocks From Southern India., Graham F. Peaslee, D. A. Carlson, E. C. Hansen, S. S. Hendrickson, R. J. Timmer, A. L. Van Wyngarden, J. D. Wilcox
Faculty Publications
The Hope College PIXE facility was used to perform an analysis of zircons, apatites and monazites prevalent in rocks collected in southern India. Thin sections of the samples were prepared for electron microprobe analysis at U. Chicago, and a number of rare earth elements were quantitatively measured. These samples were then fractured and individual crystals were analyzed with 2.3 MeV protons in an internal PIXE irradiation chamber. GUPIX II© software was used to identify and measure trace metals in the samples and the results have been correlated with the electron microprobe data. Whole rock analyses, prepared by making pressed pellets …
Impact Parameter Dependence Of Light Charged Particle Production In 25 A Mev 16o On Tb, Ta And 35 A Mev 14n On Sm And Ta, D. Prindle, A. Elmaani, C. Hyde-Wright, W. Jiang, A. A. Sonzogni, R. Vandenbosch, D. Bowman, G. Cron, P. Danielewicz, J. Dinius, W. Hsi, W. G. Lynch, C. Montoya, Graham F. Peaslee, C. Schwarz, M. B. Tsang, C. Williams, R. T. De Souza, D. Fox, T. Moore
Impact Parameter Dependence Of Light Charged Particle Production In 25 A Mev 16o On Tb, Ta And 35 A Mev 14n On Sm And Ta, D. Prindle, A. Elmaani, C. Hyde-Wright, W. Jiang, A. A. Sonzogni, R. Vandenbosch, D. Bowman, G. Cron, P. Danielewicz, J. Dinius, W. Hsi, W. G. Lynch, C. Montoya, Graham F. Peaslee, C. Schwarz, M. B. Tsang, C. Williams, R. T. De Souza, D. Fox, T. Moore
Faculty Publications
The impact parameter dependence of light charged particle (p,d,t,α) emission has been studied using an impact parameter selection based on coincident detection of residues or fission fragments. The energy spectra at twelve angles between 20° and 150° have been fit by a multiple moving source parametrization. The angle and energy integrated preequilibrium proton multiplicities decrease with increasing impact parameter in qualitative agreement with a Fermi jet calculation. The preequilibrium d/p and t/p multiplicities increase slowly with increasing impact parameter and are nearly identical at the two bombarding energies. The preequilibrium α/p ratio shows a less consistent dependency on impact parameter …
Disappearance Of Rotational Flow And Reaction Plane Dispersions In Kr+Au Collisions, W. Q. Shen, M. B. Tsang, N. Carlin, R. J. Charity, J. Feng, C. K. Gelbke, W. C. Hsi, M. J. Huang, G. J. Kunde, M-C. Lemaire, M. A. Lisa, W. G. Lynch, U. Lynen, Y. G. Ma, Graham F. Peaslee, L. Phair, J. Pochodzalla, H. Sann, C. Schwarz, L. G. Sobotka, R. T. De Souza, S. R. Souza, W. Trautmann, C. Williams
Disappearance Of Rotational Flow And Reaction Plane Dispersions In Kr+Au Collisions, W. Q. Shen, M. B. Tsang, N. Carlin, R. J. Charity, J. Feng, C. K. Gelbke, W. C. Hsi, M. J. Huang, G. J. Kunde, M-C. Lemaire, M. A. Lisa, W. G. Lynch, U. Lynen, Y. G. Ma, Graham F. Peaslee, L. Phair, J. Pochodzalla, H. Sann, C. Schwarz, L. G. Sobotka, R. T. De Souza, S. R. Souza, W. Trautmann, C. Williams
Faculty Publications
Two-particle azimuthal correlations have been used to extract reaction plane dispersion free triple-differential cross sections for d, t, and α particles for the midcentral collisions of 84Kr+197Au at E/A=35, 55, and 70 MeV. Both experimental measurements and extrapolations from lower incident energies suggest that rotational flow disappears at E/A≈100 MeV for light charged particles and that reaction plane dispersions introduce large uncertainties in extracting the disappearance of rotational flow.
Radical Ion Probes. 8. Direct And Indirect Electrochemistry Of 5,7-Di-Tert-Butylspiro[2.5]Octa-4,7-Dien-6-One And Derivatives, J. Paige Phillips, Jason G. Gillmore, Phillip Schwartz, Larry E. Brammer Jr., Daniel J. Berger, J. M. Tanko
Radical Ion Probes. 8. Direct And Indirect Electrochemistry Of 5,7-Di-Tert-Butylspiro[2.5]Octa-4,7-Dien-6-One And Derivatives, J. Paige Phillips, Jason G. Gillmore, Phillip Schwartz, Larry E. Brammer Jr., Daniel J. Berger, J. M. Tanko
Faculty Publications
Results pertaining to the direct and indirect electrochemistry of 5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1a), 1-methyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1b), and 1,1,-dimethyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1c) are reported. Product analyses reveal that reduction of all these substrates leads to cyclopropane ring-opened products; ring opening occurs with modest selectivity leading to the more substituted (stable) distonic radical anion. The direct electrochemistry of these compounds is characterized by rate limiting electron transfer (with α ≈ 0.5), suggesting that while ring opening is extremely rapid, the radical anions do have a discrete lifetime (i.e., electron transfer and ring opening are not concerted). Utilizing homogeneous redox catalysis, rate constants for electron transfer between 1a, …
Fragment Distributions For Highly Charged Systems, C. Williams, W. G. Lynch, C. Schwarz, M. B. Tsang, W. C. Hsi, M. J. Huang, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, L. Phair, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin
Fragment Distributions For Highly Charged Systems, C. Williams, W. G. Lynch, C. Schwarz, M. B. Tsang, W. C. Hsi, M. J. Huang, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, L. Phair, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin
Faculty Publications
Charge and transverse energy distributions for intermediate mass fragments have been extracted for central 84Kr+197Au collisions at E/A=35-400 MeV. The slopes of the measured fragment charge distributions decrease monotonically with incident energy, consistent with the expectations for highly charged systems, but not with recent critical exponent analyses. Statistical model calculations, which reproduce the experimental trends, suggest that post-breakup fragment secondary decays alter significantly the observed charge distributions. Radial expansion velocities extracted from these calculations follow the systematics of Au+Au collisions.
Fragment Multiplicity Dependent Charge Distributions In Heavy Ion Collisions, M. B. Tsang, C. Williams, M. J. Huang, W. G. Lynch, L. Phair, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, W. C. Hsi, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, C. Schwarz, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin
Fragment Multiplicity Dependent Charge Distributions In Heavy Ion Collisions, M. B. Tsang, C. Williams, M. J. Huang, W. G. Lynch, L. Phair, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, W. C. Hsi, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, C. Schwarz, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin
Faculty Publications
The dependence of intermediate-mass-fragment (IMF) element distributions on the multiplicity, NIMF, of detected fragments has been measured for 84Kr+197Au collisions at E/A=35, 55, 70, 100, 200, and 400 MeV. The observed dependence can be parametrized as P(NIMF|Z)∝P(Z)exp(-c⋅NIMF⋅Z), where c is a beam-energy and excitation-energy dependent parameter. Previous work indicated this parameter is zero in the liquid-gas coexistence region and positive in the gaseous phase. In contrast, we observe both negative and positive values for c, revealing the meaning of this parameter to be less straightforward than previously assumed. The magnitude of c appears nonetheless to provide a nontrivial test of …
Investigating The Evolution Of Multifragmenting Systems With Fragment Emission Order, E. W. Cornell, T. M. Hamilton, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, W. A. Friedman
Investigating The Evolution Of Multifragmenting Systems With Fragment Emission Order, E. W. Cornell, T. M. Hamilton, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, W. A. Friedman
Faculty Publications
Multifragment decays of central collisions in 84Kr+197Au at E/A=70MeV are studied. By utilizing a technique sensitive to the emission order of fragments, it is deduced that carbon fragments are emitted prior to beryllium fragments when these fragments have the same velocity. This observation is consistent with the cooling of a thermally decaying source.
Searching For The Nuclear Liquid-Gas Phase Transition In Au + Au Collisions At 35 Mev/Nucleon, M. Belkacem, P. F. Mastinu, V. Latora, A. Bonasera, M. D'Agostino, M. Bruno, J. D. Dinius, M. L. Fiandri, F. Gramegna, D. O. Handzy, W. C. Hsi, M. Huang, G. V. Margagliotti, P. M. Milazzo, C. P. Montoya, Graham F. Peaslee, R. Rui, C. Schwarz, G. Vannini, C. Williams
Searching For The Nuclear Liquid-Gas Phase Transition In Au + Au Collisions At 35 Mev/Nucleon, M. Belkacem, P. F. Mastinu, V. Latora, A. Bonasera, M. D'Agostino, M. Bruno, J. D. Dinius, M. L. Fiandri, F. Gramegna, D. O. Handzy, W. C. Hsi, M. Huang, G. V. Margagliotti, P. M. Milazzo, C. P. Montoya, Graham F. Peaslee, R. Rui, C. Schwarz, G. Vannini, C. Williams
Faculty Publications
Within the framework of classical molecular dynamics, we study the collision Au+Au at an incident energy of 35 MeV/nucleon. It is found that the system shows a critical behavior at peripheral impact parameters, revealed through the analysis of conditional moments of charge distributions, Campi scatter plot, and the occurrence of large fluctuations in the region of the Campi plot where this critical behavior is expected. When applying the experimental filters of the MULTICS-MINIBALL apparatus, it is found that criticality signals can be hidden due to the inefficiency of the experimental apparatus. The signals are recovered by identifying semiperipheral and peripheral …
Mass Dependence Of Directed Collective Flow, M. J. Huang, R. C. Lemmon, F. Daffin, W. G. Lynch, C. Schwarz, M. B. Tsang, C. Williams, P. Danielewicz, K. Haglin, W. Bauer, N. Carlin, R. J. Charity, R. T. De Souza, C. K. Gelbke, W. C. Hsi, G. J. Kunde, M. C. Lemaire, M. A. Lisa, U. Lynen, Graham F. Peaslee, J. Pochodzalla, H. Sann, L. G. Sobotka, S. R. Souza, W. Trautmann
Mass Dependence Of Directed Collective Flow, M. J. Huang, R. C. Lemmon, F. Daffin, W. G. Lynch, C. Schwarz, M. B. Tsang, C. Williams, P. Danielewicz, K. Haglin, W. Bauer, N. Carlin, R. J. Charity, R. T. De Souza, C. K. Gelbke, W. C. Hsi, G. J. Kunde, M. C. Lemaire, M. A. Lisa, U. Lynen, Graham F. Peaslee, J. Pochodzalla, H. Sann, L. G. Sobotka, S. R. Souza, W. Trautmann
Faculty Publications
Sidewards directed fragment flow has been extracted for 84Kr+197Au collisions at E/A=200MeV, using techniques that are free of reaction plane dispersion. The fragment flow per nucleon increases with mass, following a thermal or coalescencelike behavior, and attains roughly constant limiting values at 4≤A≤12. Comparisons of the impact parameter dependences of the measured coalescence-invariant proton flow to Boltzmann-Uehling-Uhlenbeck calculations clearly favor a momentum dependent nuclear mean field.
Universality Of Spectator Fragmentation At Relativistic Bombarding Energies, A. Schüttauf, W. D. Kunze, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, C. Groß, W. C. Hsi, J. Hubele, G. Immé, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, F. Rosenberger, Th. Rubehn, H. Sann, C. Schwarz, W. Seidei, V. Serfling
Universality Of Spectator Fragmentation At Relativistic Bombarding Energies, A. Schüttauf, W. D. Kunze, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, C. Groß, W. C. Hsi, J. Hubele, G. Immé, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, F. Rosenberger, Th. Rubehn, H. Sann, C. Schwarz, W. Seidei, V. Serfling
Faculty Publications
Multi-fragment decays of 129Xe, 197Au and 238U projectiles in collisions with Be, C, Al, Cu, In, Au and U targets at energies between View the MathML source and 1000 MeV have been studied with the ALADIN forward-spectrometer at SIS. By adding an array of 84 SiCsI(Tl) telescopes the solid-angle coverage of the setup was extended to θlab = 16°. This permitted the complete detection of fragments from the projectile-spectator source. The dominant feature of the systematic set of data is the Zbound universality that is obeyed by the fragment multiplicities and correlations. These observables are invariant with respect to the …
Charge Correlations And Dynamical Instabilities In The Multifragment Emission Process, L. G. Moretto, Th. Rubehn, L. Phair, N. Colonna, G. J. Wozniak, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, C. Williams
Charge Correlations And Dynamical Instabilities In The Multifragment Emission Process, L. G. Moretto, Th. Rubehn, L. Phair, N. Colonna, G. J. Wozniak, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, C. Williams
Faculty Publications
A new, sensitive method allows one to search for the enhancement of events with nearly equal-sized fragments as predicted by theoretical calculations based on volume or surface instabilities. Simulations have been performed to investigate the sensitivity of the procedure. Experimentally, charge correlations of intermediate mass fragments emitted from heavy ion reactions at intermediate energies have been studied. No evidence for a preferred breakup into equal-sized fragments has been found.
Reducibility, Thermal And Mass Scaling In Angular Correlations From Multifragmentation Reactions, L. Phair, L. G. Moretto, G. J. Wozniak, R. T. De Souza, 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
Reducibility, Thermal And Mass Scaling In Angular Correlations From Multifragmentation Reactions, L. Phair, L. G. Moretto, G. J. Wozniak, R. T. De Souza, 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
The azimuthal angular correlations of light charged particles and light intermediate mass fragments emitted from the reaction 36Ar+197Au at E/A=50MeV are found to be reducible to the angular distributions of individual fragments. Thermal scaling is also observed in the coefficients of the angular correlations. Furthermore, the observed scaling with fragment mass seems to imply secondary emission from relatively small ( A≈15–30) primary fragments.
Changing Source Characteristics During Multifragment Decay, T. M. Hamilton, E. Cornell, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, T. Glasmacher, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, A. A. Sonzogni, D. Prindle
Changing Source Characteristics During Multifragment Decay, T. M. Hamilton, E. Cornell, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, T. Glasmacher, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, A. A. Sonzogni, D. Prindle
Faculty Publications
The spatial-temporal extent of the emitting system for central collisions in Kr84 + Au197 at E/A = 35, 55, and 70 MeV is probed using fragment-fragment velocity correlation functions. Selection on fragment pairs of high velocity yields a stronger fragment-fragment Coulomb interaction than for inclusive fragment pairs. This result is consistent with fragment emission from a source of decreased spatial-temporal extent. The universality of this association and the effect of different selection criteria are explored. The sensitivity of the spatial-temporal extent deduced by the correlation function technique to measurement uncertainties, assumed source characteristics, and rotational effects is assessed.
Circumstantial Evidence For A Critical Behavior In Peripheral Au+Au Collisions At 35 Mev/Nucleon, P. F. Mastinu, M. Belkacem, M. D'Agostino, M. Bruno, P. M. Milazzo, G. Vannini, D. R. Bowman, N. Colonna, J. D. Dinius, A. Ferrero, M. L. Fiandri, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, W. C. Hsi, M. Huang, I. Iori, G. J. Kunde, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, C. P. Montoya, A. Moroni, Graham F. Peaslee, F. Petruzzelli, R. Rui, C. Schwarz, M. B. Tsang, C. Williams, V. Latora, A. Bonasera
Circumstantial Evidence For A Critical Behavior In Peripheral Au+Au Collisions At 35 Mev/Nucleon, P. F. Mastinu, M. Belkacem, M. D'Agostino, M. Bruno, P. M. Milazzo, G. Vannini, D. R. Bowman, N. Colonna, J. D. Dinius, A. Ferrero, M. L. Fiandri, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, W. C. Hsi, M. Huang, I. Iori, G. J. Kunde, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, C. P. Montoya, A. Moroni, Graham F. Peaslee, F. Petruzzelli, R. Rui, C. Schwarz, M. B. Tsang, C. Williams, V. Latora, A. Bonasera
Faculty Publications
The fragmentation resulting from peripheral Au+Au collisions at an incident energy of E=35MeV/nucleon is investigated. A power-law charge distribution, A−τ with τ≈2.2, and an intermittency signal are observed for events selected in the region of the Campi scatter plot where “critical” behavior is expected.
Squeeze-Out Of Nuclear Matter In Au + Au Collisions, M. B. Tsang, P. Danielewicz, W. C. Hsi, M. Huang, W. G. Lynch, D. R. Bowman, C. K. Gelbke, M. A. Lisa, Graham F. Peaslee, R. J. Charity, L. G. Sobotka, M. L. Begemann-Blaich, F. Cosmo, A. Ferrero, J. Hubele, G. Imme, I. Iori, J. Kempter, P. Kruetz, G. J. Kunde, W. D. Kunze, V. Lindenstruth, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, J. Pochodzalla, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidel
Squeeze-Out Of Nuclear Matter In Au + Au Collisions, M. B. Tsang, P. Danielewicz, W. C. Hsi, M. Huang, W. G. Lynch, D. R. Bowman, C. K. Gelbke, M. A. Lisa, Graham F. Peaslee, R. J. Charity, L. G. Sobotka, M. L. Begemann-Blaich, F. Cosmo, A. Ferrero, J. Hubele, G. Imme, I. Iori, J. Kempter, P. Kruetz, G. J. Kunde, W. D. Kunze, V. Lindenstruth, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, J. Pochodzalla, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidel
Faculty Publications
Emission of charged particles from a compressed reaction zone is studied for Au197+197Au collisions at E/A=100, 250, and 400 MeV. Using a modified coalescence invariant weighting, squeeze-out ratios are determined and compared to predictions of cascade and BUU transport-model calculations.
Squeeze-Out Of Nuclear Matter In Au+Au Collisions, M. B. Tsang, P. Danielewicz, W. C. Hsi, M. Huang, W. G. Lynch, D. R. Bowman, C. K. Gelbke, M. A. Lisa, Graham F. Peaslee, R. J. Charity, L. G. Sobotka, M. L. Begemann-Blaich, F. Cosmo, A. Ferrero, J. Hubele, G. Imme, I. Iori, J. Kempter, G. J. Kunde, W. D. Kunze, V. Lindenstruth, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilive, J. Pochodzalla, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidel, V. Serfling
Squeeze-Out Of Nuclear Matter In Au+Au Collisions, M. B. Tsang, P. Danielewicz, W. C. Hsi, M. Huang, W. G. Lynch, D. R. Bowman, C. K. Gelbke, M. A. Lisa, Graham F. Peaslee, R. J. Charity, L. G. Sobotka, M. L. Begemann-Blaich, F. Cosmo, A. Ferrero, J. Hubele, G. Imme, I. Iori, J. Kempter, G. J. Kunde, W. D. Kunze, V. Lindenstruth, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilive, J. Pochodzalla, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidel, V. Serfling
Faculty Publications
Emission of charged particles from a compressed reaction zone is studied for Au197+197Au collisions at E/A=100, 250, and 400 MeV. Using a modified coalescence invariant weighting, squeeze-out ratios are determined and compared to predictions of cascade and BUU transport-model calculations.
Statistical Multifragmentation In Central Au+Au Collisions At 35 Mev/U, M. D'Agostino, A. S. Botvina, P. M. Milazzo, M. Bruno, G. J. Kunde, D. R. Bowman, L. Celano, N. Colonna, J. D. Dinius, A. Ferrero, M. L. Fiandri, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, W. C. Hsi, M. Huang, I. Iori, M. A. Lisa, W. G. Lynch, L. Manduci, G. V. Margagliotti, P. F. Mastinu, I. N. Mishustin, C. P. Montoya, A. Moroni, Graham F. Peaslee, F. Petruzzelli, L. Phair, R. Rui, C. Schwarz, M. B. Tsang, G. Vannini, C. Williams
Statistical Multifragmentation In Central Au+Au Collisions At 35 Mev/U, M. D'Agostino, A. S. Botvina, P. M. Milazzo, M. Bruno, G. J. Kunde, D. R. Bowman, L. Celano, N. Colonna, J. D. Dinius, A. Ferrero, M. L. Fiandri, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, W. C. Hsi, M. Huang, I. Iori, M. A. Lisa, W. G. Lynch, L. Manduci, G. V. Margagliotti, P. F. Mastinu, I. N. Mishustin, C. P. Montoya, A. Moroni, Graham F. Peaslee, F. Petruzzelli, L. Phair, R. Rui, C. Schwarz, M. B. Tsang, G. Vannini, C. Williams
Faculty Publications
Multifragment disintegrations, measured for central Au + Au collisions at , are analyzed with the Statistical Multifragmentation Model. Charge distributions, mean fragment energies, and two-fragment correlation functions are well reproduced by the statistical breakup of a large, diluted and thermalized system slightly above the multifragmentation threshold.