High-Spin States in Nuclei Excited Via (p,n) Reactions

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

Warming Up Density Functional Theory

Density functional theory (DFT) has become the most popular approach to electronic structure across disciplines, especially in material and chemical sciences. Last year, at least 30,000 papers used DFT to make useful predictions or give insight into an enormous diversity of scientific problems, ranging from battery development to solar cell efficiency and far beyond. The success of this field has been driven by usefully accurate approximations based on known exact conditions and careful testing and validation. In the last decade, applications of DFT in a new area, warm dense matter, have exploded. DFT is revolutionizing simulations of warm dense matter including applications in controlled fusion, planetary interiors, and other areas of high energy density physics. Over the past decade or so, molecular dynamics calculations driven by modern density functional theory have played a crucial role in bringing chemical realism to these applications, often (but not always) with excellent agreement with experiment. This chapter summarizes recent work from our group on density functional theory at non-zero temperatures, which we call thermal DFT. We explain the relevance of this work in the context of warm dense matter, and the importance of quantum chemistry to this regime. We illustrate many basic concepts on a simple model system, the asymmetric Hubbard dimer

High-Spin States and Spin-Coupled Quadrupole Vibrational States in Nuclei Excited Via (p,n) Reactions

This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit

Hydrogen-Helium Mixtures at High Pressure

The properties of hydrogen-helium mixtures at high pressure are crucial to address important questions about the interior of Giant planets e.g. whether Jupiter has a rocky core and did it emerge via core accretion? Using path integral Monte Carlo simulations, we study the properties of these mixtures as a function of temperature, density and composition. The equation of state is calculated and compared to chemical models. We probe the accuracy of the ideal mixing approximation commonly used in such models. Finally, we discuss the structure of the liquid in terms of pair correlation functions.Comment: Proceedings article of the 5th Conference on Cryocrystals and Quantum Crystals in Wroclaw, Poland, submitted to J. Low. Temp. Phys. (2004

The Equation of State and the Hugoniot of Laser Shock-Compressed Deuterium

The equation of state and the shock Hugoniot of deuterium are calculated using a first-principles approach, for the conditions of the recent shock experiments. We use density functional theory within a classical mapping of the quantum fluids [ Phys. Rev. Letters, {\bf 84}, 959 (2000) ]. The calculated Hugoniot is close to the Path-Integral Monte Carlo (PIMC) result. We also consider the {\it quasi-equilibrium} two-temperature case where the Deuterons are hotter than the electrons; the resulting quasi-equilibrium Hugoniot mimics the laser-shock data. The increased compressibility arises from hot $D^+-e$ pairs occuring close to the zero of the electron chemical potential.Comment: Four pages; One Revtex manuscript, two postscipt figures; submitted to PR

Constraints on the Mineralogy of Gale Crater Mudstones from MSL SAM Evolved Water

The Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments on the Mars Science Laboratory (MSL) have analysed more than 150 micron fines from 14 sites at Gale Crater. Here we focus on the mudstone samples. Two were drilled from sites John Klein (JK) and Cumberland (CB) in the Sheepbed mudstone. Six were drilled from Murray Formation mudstone: Confidence Hills (CH), Mojave (MJ), Telegraph Peak (TP), Buckskin (BK), Oudam (OU), Marimba (MB). SAM's evolved gas analysis mass spectrometry (EGA-MS) detected H2O, CO2, O2, H2, SO2, H2S, HCl, NO, and other trace gases, including organic fragments. The identity and evolution temperature of evolved gases can support CheMin mineral detection and place constraints on trace volatile-bearing phases or phases difficult to characterize with X-ray diffraction (e.g., amorphous phases). Here we will focus on SAM H2O data and comparisons to SAM-like analyses of key reference materials

A review of tennis racket performance parameters

The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and biomechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swingweights of around 0.030–0.035 kg/m2 are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions

Differential cross sections for pion charge exchange on the proton at 27.5 MeV

We have measured pion single charge exchange differential cross sections on the proton at 27.5 MeV incident $\pi^-$ kinetic energy in the center of momentum angular range between $0^\circ$ and $55^\circ$. The extracted cross sections are compared with predictions of the standard pion-nucleon partial wave analysis and found to be in excellent agreement.Comment: ReVTeX v3.0 with aps.sty, 23 pages in e-print format, 7 PostScript Figures and 4 Tables, also available via anonymous ftp at ftp://helena.phys.virginia.edu/pub/preprints/scx.p

The (p,n) Reaction at Intermediate Energies with the Isotopes of Oxygen (16-O, 17-O, 18-O) and 9-Be as Part of a Unified Approach to the Study of These Nuclei

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

The (p,n) Reaction at Intermediate Energies With the Isotopes of Oxygen (16-O, 17-O, 18-O) and 9-Be as Part of a Unified Approach to the Study of These Nuclei

This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit