Publications (291)839.93 Total impact
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ABSTRACT: An analysis of six different sets of experimental data indicates that infinite, neutronproton symmetric, neutral nuclear matter has a critical temperature of T c = 17.9 ± 0.4 MeV, a critical density of ρ c = 0.06 ± 0.01 nucleons/fm 3 , and a critical pressure of p c = 0.31 ± 0.07 MeV/fm 3 . These values have been obtained by analyzing data from six different reactions studied in three experiments: two "compound nuclear" reactions, 58 Ni + 12 C → 70 Se and 64 Ni + 12 C → 76 Se (both performed at the LBNL 88in. cyclotron); and four "multifragmentation" reactions, 1 GeV/c π + 197 Au (performed by the Indiana Silicon Sphere Collaboration), 1 GeV/nucleon 197 Au+ 12 C, 1 GeV/nucleon 139 La+ 12 C, and 1 GeV/nucleon 84 Kr+ 12 C (all performed by the Equation of State Collaboration). The charge yields of all reactions as a function of the excitation energy were fit with a version of Fisher's droplet model modified to account for the dual components of the fluid (i.e., protons and neutrons), Coulomb effects, finitesize effects, and angular momentum arising from the nuclear collisions. 
Article: New Wrinkles on an Old Model: Correlation Between Liquid Drop Parameters and Curvature Term
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ABSTRACT: The relationship between the volume and the surface energy coefficients in the liquid drop A1/3 expansion of nuclear masses is discussed. The volume and surface coefficients share the same physical origin and their physical connection is used to extend the expansion with a curvature term. This connection between coefficients is used to fit the experimental nuclear masses. The excellent fit obtained with a smaller number of parameters validates the assumed physical connections and the usefulness of the curvature term.  [Show abstract] [Hide abstract]
ABSTRACT: The relationship between the volume and the surface energy coefficients in the liquid drop A−1/3 expansion of nuclear masses is discussed. The volume and surface coefficients share the same physical origin and their physical connection is used to extend the expansion with a curvature term. A possible generalization of the Wigner term is also suggested. This connection between coefficients is used to fit the experimental nuclear masses. The excellent fit obtained with a smaller number of parameters validates the assumed physical connections and the usefulness of the curvature term.  [Show abstract] [Hide abstract]
ABSTRACT: Infinite, neutronproton symmetric, neutral nuclear matter has a critical temperature of 17.9+0.4 MeV, a critical density of 0.06+0.01 nucleons per cubic fermi and a critical pressure of 0.31+0.07 MeV per cubic fermi. These values have been obtained from our analysis of data from six different reactions studied in three different experiments: two "compound nuclear" reactions: 58Ni+12C>70Se and 64Ni+12C>76Se (both performed at the LBNL 88" Cyclotron) and four "multifragmentation" reactions: 1 GeV/c pi+197Au (performed by the ISiS collaboration), 1 AGeV 197Au+C, 1 AGeV 139La+12C and 1 AGeV 84Kr+12C (all performed by the EOS collaboration). The charge yields of all reactions as a function of excitation energy were fit with a version of Fisher's droplet model modified to account for the dual components of the fluid (i.e. protons and neutrons), Coulomb effects, finite size effects and angular momentum arising from the nuclear collisions.  [Show abstract] [Hide abstract]
ABSTRACT: The finite size of nuclei and the Coulomb interaction make it difficult to describe systems interacting through the strong force into thermodynamic terms. Our task is to extract the phase diagram of the theoretical infinite symmetrical uncharged nuclear matter from experiments of nuclear collisions where the systems are neither infinite, symmetrical, nor uncharged. Decay yields from such experiments are translated into coexistence densities and pressures by use of Fisher's droplet model. This method is tested on model systems such as the Ising model and a system of particles interacting via the LennardJones potential. The specific problems inherent to nuclear reactions are considered. These include finite size effects, Coulomb repulsion, and the lack of a physical vapor in contact with a decaying system. Experimental data of compound nucleus experiments are studied within this framework, which is also shown to extend to higher energy reactions. Finally, the phase diagram of nuclear matter is extracted.  [Show abstract] [Hide abstract]
ABSTRACT: The modern investigation of clusters, for which 1 N ∞, requires a generalization of the thermodynamics developed for infinite systems. For instance, in finite systems, phase transitions and phase coexistence become illdefined with ambiguous signals. The existence of phase transitions in nuclear systems, in particular of the liquid–vapor kind, has been widely discussed and even experimentally claimed. A consistent and unambiguous approach to this problem requires a connection between finite systems and the corresponding infinite systems. Historically, this has been achieved at temperature T = 0 by the introduction of the liquid drop model and the extraction of the volume term, which is a fundamental quantity of nuclear matter. This work extends this approach to T > 0, by determining the liquid–vapor coexistence line and its termination at the critical point. Since there is no known experimental situation where a nuclear liquid and vapor are in coexistence, we establish a relationship between evaporation rates and saturated vapor concentration and characterize the saturated vapor with Fisher's droplet model. We validate this approach by analyzing cluster concentrations in the Ising and LennardJones models and extracting the corresponding firstorder coexistence line and critical temperature. Since the vapor of clusters coexists with a finite liquid drop, we devise a finite size correction leading to a modified Fisher equation. The application of the above techniques to nuclear systems requires dealing also with the Coulomb force. Nuclear cluster evaporation rates can be corrected for Coulomb effects and can be used to evaluate the cluster concentrations in the 'virtual' equilibrium vapor. These cluster concentrations, determined over a wide temperature range, can be analyzed by means of a modified Fisher formula. This leads to the extraction of the entire liquid–vapor coexistence line terminating at the critical point. A large body of experimental data has been analyzed in this manner and the liquid–vapor phase diagram of nuclear matter has been extracted. 
Article: Channel selection of neutronrich nuclei following fusionevaporation reactions of light systems
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ABSTRACT: a b s t r a c t Experimental results for the minor decay channels of fusionevaporation in light projectile plus light target systems are presented. These new data were obtained during test campaigns to measure the opening of different decay channels. Experiments were designed to provide relative crosssection information on weakly populated channels for gammaray spectroscopy experiments in coincidence with chargedparticles. The results are compared to publicly available fusionevaporation codes. The data follow a simple estimate which is useful in predicting experimental conditions to make the fusionevaporation reaction a viable nuclear structure tool to study weakly populated light neutronrich nuclei. & 2011 Elsevier B.V. All rights reserved.  [Show abstract] [Hide abstract]
ABSTRACT: The cluster description of near coexistence phases (e.g. Fisher theory) requires an evaluation of cluster surface entropy. This surface degeneracy can be estimated with lattice models where clusters appear. The maximum probability lies near the maximum cluster surface. At low temperatures, clusters are forced to be nearly spherical by the surface energy and the associated Boltzmann factor. At higher temperatures and near criticality, the fractal dimension of clusters changes so that clusters become fractal. In the MIT bag model, where there is no surface energy, bags are always fractal. 
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ABSTRACT: A gas of MIT bags has peculiar properties, one of which is that of not existing. We shall discuss its instability against coalescence. The absence of surface energy makes the bags already critical at their unique temperature TH. The addition of a surface energy does not seem to cure the problem. 
Article: Phase transitions in hadronic systems and thermodynamics of a system with an exponential spectrum
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ABSTRACT: Both nuclear matter and hadronic matter at high excitations can be described by a liquidvapor phase transition. For the hadronic systems, a system with an exponential mass spectrum (Hagedornlike or baglike) leads to a thermodynamics which is identical to that of a two phase coexistence at a fixed temperature.  [Show abstract] [Hide abstract]
ABSTRACT: The fusionevaporation reaction 9Be(11B,2p) was used to populate excited states in 18N. New gammaray transitions were added to the 18N level scheme. The mean lifetime of the first excited state was measured to be 582(165) ps and its transition rate to the ground state was determined to be B(M1)=0.036(10) W.u. Shell model calculations in the full psd model space were used to investigate the lowlying configurations in 18N and in the N=11 isotones 17C and 19O. It was found that the role of the protonneutron interaction is important in determining the ground state and lowlying excited state properties. The ground state spin inversion in these isotones is attributed to the increased importance of the quadrupole relative to the pairing interaction and is discussed within the framework of a schematic pairing + quadrupole model.  [Show abstract] [Hide abstract]
ABSTRACT: The lifetime of the ${2}_{1}^{+}$ state in $^{16}\mathrm{C}$ has been measured with the recoil distance method using the $^{9}\mathrm{Be}(^{9}\mathrm{Be},2p)$ fusionevaporation reaction at a beam energy of 40 MeV. The mean lifetime was measured to be 11.7(20) ps corresponding to a $B(E2;\text{ }\text{ }{2}_{1}^{+}$\rightarrow${}{0}^{+})$ value of $4.15(73){e}^{2}\text{ }\text{ }{\mathrm{fm}}^{4}$ [1.73(30) W.u.], consistent with other eveneven closed shell nuclei. Our result does not support an interpretation for ``decoupled'' valence neutrons.  [Show abstract] [Hide abstract]
ABSTRACT: Over the past three years we have studied various surrogate reactions (d,p), (3He,t), (α,α′) on several uranium isotopes 234U, 235U, 236U, and 238U. An overview of the STARS∕LIBERACE surrogate research program as it pertains to the actinides is discussed. A summary of results to date will be presented along with a discussion of experimental difficulties encountered in surrogate experiments and future research directions.  [Show abstract] [Hide abstract]
ABSTRACT: We have extracted the critical parameters of infinite uncharged nuclear matter from experimental nuclear fragmentation data. To do this, three obstacles had to be overcome: finite size effects, the Coulomb interaction, and an appropriate physical picture (not particles contained in a box) that reflects particle emission into a vacuum. 
Article: The Fission Barrier Landscape
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ABSTRACT: Fission excitation functions have been measured for a chain of neighboring compound nuclei from 207Po to 212Po. We present a new analysis which provides a determination of the fission barriers and ground state shell effects with nearly spectroscopic accuracy. The accuracy achieved in this analysis may lead to a future detailed exploration of the saddle mass surface and its spectroscopy. 
Article: Symmetry entropy and isoscaling
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ABSTRACT: We suggest, on general principles, that the isotopic distributions and thus isoscaling are affected by an entropic symmetry term, which is present even when the symmetry energy term is absent. 
Article: Transition Rate Measurement in ^18N
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ABSTRACT: Previous information on excited states of ^18N has been obtained from selective reaction mechanisms such as betadecay and charge exchange reactions only. This work is the first to successfully utilize the nonselective ^9Be(^11B,2p)^18N fusionevaporation reaction to extract structure information. The LIBERACESTARS detector array  an array of largearea segmented silicon detectors (EdeltaE) and Compton suppressed HPGe Clover detectors  was used to detect the charged particles and gamma radiation, respectively. New gamma transitions were added to the ^18N level scheme and the B(M1) from the first excited state to the ground state was determined to be 0.01 W.u. < B(M1) < 3.6 W.u. Shell model calculations were used to study the lowlying configurations of ^18N and its oddA neighbors ^17C and ^19O (N=11 isotones). The role of proton holes in determining the evolution of ground state and lowlying excited state properties of these N=11 isotones will be discussed. 
Article: Mesoscopy and thermodynamics
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ABSTRACT: The interplay of thermodynamics and statistical mechanics is discussed with special attention to mesoscopic systems and phase transitions.  [Show abstract] [Hide abstract]
ABSTRACT: This document gives a historical review of the scaling of particles yields emitted from excited nuclei. The focus will be on what scaling is, what can be learned from scaling, the underlying theory of why one might expect particle yields to scale, how experimental particle yields have been observed to scale, model systems where particle (cluster) yields do scale and finally scaling observed in the particle yields of various low and medium energy nuclear reaction experiments. The document begins with a basic introduction to scaling in the study of critical phenomena and then reviews Fisher's theory which has all the aspects of scaling and can be directly applied to the counting of clusters, the most reliable measurement accessible to the experimental study of nuclear reactions. Also this document gives a history of the various scalings observed in nuclear reaction experiments and culminates with an estimate of the nuclear liquidvapor phase boundary based upon measured particle yields.
Publication Stats
6k  Citations  
839.93  Total Impact Points  
Top Journals
 Nuclear Physics A (45)
 Physical Review C (31)
 Physics Letters B (27)
 Physical Review Letters (24)
 Physical Review Letters (22)
Institutions

19852013

Lawrence Berkeley National Laboratory
 • Nuclear Science Division
 • Accelerator and Fusion Research Division
Berkeley, California, United States


19692012

University of California, Berkeley
 • Lawrence Berkeley Laboratory
 • Department of Chemistry
Berkeley, California, United States


2010

Lawrence Livermore National Laboratory
 Physical & Life Sciences Directorate
Livermore, California, United States


19921995

Michigan State University
 Department of Physics and Astronomy
ИстЛансинг, Michigan, United States


1993

Stanford University
 Department of Physics
Stanford, California, United States


1991

University of Maryland, College Park
 Department of Chemistry and Biochemistry
CGS, Maryland, United States


1984

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy


1983

Max Planck Institute for Nuclear Physics
Heidelburg, BadenWürttemberg, Germany


19711972

University of Pavia
 Department of Chemistry
Ticinum, Lombardy, Italy
