Superfluid Pairing in Neutrons and Cold Atoms

Ultracold atomic gases and low-density neutron matter are unique in that they exhibit pairing gaps comparable to the Fermi energy which in this sense are the largest in the laboratory and in nature, respectively. This strong pairing regime, or the crossover between BCS and BEC regimes, requires non-perturbative treatments. We describe Quantum Monte Carlo results useful to understand the properties of these systems, including infinite homogeneous matter and trapped inhomogeneous gases.Comment: 14 pages, 4 figures; chapter in "50 Years of Nuclear BCS", edited by R. A. Broglia and V. Zelevinsk

THERMTRAJ: A FORTRAN program to compute the trajectory and gas film temperatures of zero pressure balloons

A FORTRAN computer program called THERMTRAJ is presented which can be used to compute the trajectory of high altitude scientific zero pressure balloons from launch through all subsequent phases of the balloon flight. In addition, balloon gas and film temperatures can be computed at every point of the flight. The program has the ability to account for ballasting, changes in cloud cover, variable atmospheric temperature profiles, and both unconditional valving and scheduled valving of the balloon gas. The program was verified for an extensive range of balloon sizes (from 0.5 to 41.47 million cubic feet). Instructions on program usage, listing of the program source deck, input data and printed and plotted output for a verification case are included

A unified thermal and vertical trajectory model for the prediction of high altitude balloon performance

A computer model for the prediction of the trajectory and thermal behavior of zero-pressure high altitude balloon was developed. In accord with flight data, the model permits radiative emission and absorption of the lifting gas and daytime gas temperatures above that of the balloon film. It also includes ballasting, venting, and valving. Predictions obtained with the model are compared with flight data from several flights and newly discovered features are discussed

Asymmetric Two-component Fermion Systems in Strong Coupling

We study the phase structure of a dilute two-component Fermi system with attractive interactions as a function of the coupling and the polarization or number difference between the two components. In weak coupling, a finite number asymmetry results in phase separation. A mixed phase containing symmetric superfluid matter and an asymmetric normal phase is favored. With increasing coupling strength, we show that the stress on the superfluid phase to accommodate a number asymmetry increases. Near the infinite-scattering length limit, we calculate the single-particle excitation spectrum and the ground-state energy at various polarizations. A picture of weakly-interacting quasi-particles emerges for modest polarizations. In this regime near infinite scattering length, and for modest polarizations, a homogeneous phase with a finite population of excited quasi-particle states characterized by a gapless spectrum should be favored over the phase separated state. These states may be realized in cold atom experiments.Comment: 4 pages, 3 figur

Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials

We present the first Green's function Monte Carlo calculations of light nuclei with nuclear interactions derived from chiral effective field theory up to next-to-next-to-leading order. Up to this order, the interactions can be constructed in a local form and are therefore amenable to quantum Monte Carlo calculations. We demonstrate a systematic improvement with each order for the binding energies of $A=3$ and $A=4$ systems. We also carry out the first few-body tests to study perturbative expansions of chiral potentials at different orders, finding that higher-order corrections are more perturbative for softer interactions. Our results confirm the necessity of a three-body force for correct reproduction of experimental binding energies and radii, and pave the way for studying few- and many-nucleon systems using quantum Monte Carlo methods with chiral interactions.Comment: 5 pages, 3 figures, 4 tables. Updated references. Cosmetic changes to figures, tables, and equations; added a sentence clarifying the correspondence between our real-space cutoffs and momentum-space cutoffs. Other sentences were reworded for clarit

Quantum Monte Carlo Calculations of A≤6A\leq6 Nuclei

The energies of $^{3}H$, $^{3}He$, and $^{4}He$ ground states, the ${\frac{3}{2}}^{-}$ and ${\frac{1}{2}}^{-}$ scattering states of $^{5}He$, the ground states of $^{6}He$, $^{6}Li$, and $^{6}Be$ and the $3^{+}$ and $0^{+}$ excited states of $^{6}Li$ have been accurately calculated with the Green's function Monte Carlo method using realistic models of two- and three-nucleon interactions. The splitting of the $A=3$ isospin $T=\frac{1}{2}$ and $A=6$ isospin $T=1$, $J^{\pi} = 0^{+}$ multiplets is also studied. The observed energies and radii are generally well reproduced, however, some definite differences between theory and experiment can be identified.Comment: 12 pages, 1 figur

Study of thin film large area photovoltaic solar energy converter Second quarterly report, 1 Jan. - 31 Mar. 1963

Thin film large area photovoltaic solar energy converter - cadmium sulfide films producted by vacuum evaparation techniqu

Space environment operation of experimental hydrazine reactors Final report

Correlation of low temperature high vacuum hydrazine ignition properties of Shell 405 catalyst with concentration of adsorbed gase

Scaling and Duality in Semi-exclusive Processes

We discuss extending scaling and duality studies to semi-exclusive processes. We show that semi-exclusive hard pion photoproduction should exhibit scaling behavior in kinematic regions where the photon and pion both interact directly with the same quark. We show that such kinematic regions exist. We also show that the constancy with changing momentum transfer of the resonance peak/scaling curve ratio, familiar for many resonances in deep inelastic scattering, is also expected in the semi-exclusive case.Comment: 8 pages, 4 figures, submitted to Phys.Rev.