Physics Commons^™

Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb

Faculty Publications

The probability distributions for switching out of the superconducting state of low-cur-rent-density 1-μm Nb Josephson junctions with capacitance ≈ 0.1 pF have been measured as a function of temperature T down to 3 mK. Below 100 mK the distribution widths become independent of T. The results are in excellent agreement with predictions for the quantum tunneling of the (macroscopic) junction phase that include the reduction of tunneling rates due to dissipation.

Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin

Faculty Publications

Measurements of the electrical resistivity of palladium, residual resistivity ratio ∼22 500, containing 1.7 ppm of Fe have been made from 5.5 K to 1.8 mK. 15 Hz ac susceptibility measurements from 1 K to 1.8 mK together with the resistivity data suggest that a transition into a spin-glass state occurs near 7 mK.

Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb

Faculty Publications

Using a pulsed superconducting-quantum-interference-device (SQUID) NMR technique, relaxation of the longitudinal magnetization in superfluid ³He has been measured in magnetic fields of 31, 102, 180, and 306 Oe in the pressure range 16-26 bar. It is observed that in both superfluid phases there is a temperature-dependent, well-defined spin-tipping angle, θc, for which the relaxation of the magnetization changes from an exponential to a nonexponential behavior.

Ferromagneticlike Resonance Behavior In Superfluid 3he-B, Richard A. Webb

Faculty Publications

Nonlinear cw NMR behavior, similar to that observed on ferromagnets at high rf powers, has been observed in superfluid ³He-B using a superconducting quantum interference device (SQUID) magnetometer in fields of 31, 102, 180, and 308 Oe and at a pressure of 21 bar. It is observed that beyond some threshold value of the transverse H₁ field the z component of magnetization anomalously decreases and is followed by a rapid increase back to the normal resonance curve as the frequency of the H₁ field is swept through resonance.

Measurement Of The Difference Between The Dynamic Nmr And Static Susceptibilites Of Superfluid 3he-B Using An Rf-Biased Superconducting Quantum-Interference Device, Richard A. Webb

Faculty Publications

The temperature-dependent susceptiblity of superfluid ³He-B has been measured both statically and via a pulse technique in a field of 309 G using an rf-biased superconducting quantum-interference device (SQUID). In the pressure range 26.5 to 18 bar, the dynamic NMR susceptiblity agrees qualitatively with the theoretical weak-coupling predictions for the Balian-Werthamer state. However, the static susceptiblity, measured using the same rf-biased SQUID and detection system, is significantly smaller thatn the dynamic susceptibility.

Group Of Point Transformations Of Time Dependent Harmonic Oscillators, Jose Ricardo Bernal

University of the Pacific Theses and Dissertations

In general, a physical system has invariant quantities which are very often related to its symmetry and to the invariance of the equation that describe it. A detailed study of the invariance property of the differential equation will be helpful in understanding this relation.

The work is concerned with a preliminary investigation of the Lie-group which leaves invariant the Newtonian and Lagrangian equation of motion for a one-dimensional harmonic oscillator. A brief review of Ehrenfest's adiabatic principle and the later treatments on exact and adiabatic invariants will be presented.

Relaxation Of The Wall-Pinned Magnetization Ringing Mode In Superfluid 3he-B, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Observations of the wall-pinned mode in ³He-B allow new magnetic relaxation phenomena to be studied. Excepting the quantitative value of the zero-time ringing frequency, comparison of experiment with theory is satisfactory, including a linear dependence of the square of the ringing period on time and a square-root singularity near T_c in the relaxation parameter.

Nonlinear Parallel Ringing Of Magnetization In Superfluid 3he, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Experiments based on an analogy to the ac Josephson effect have shown in both ³He-A and ³He-B that a pairing theory of the superfluidity of ³He is essentially correct. Additional observations of parallel ringing are not in agreement with the simple "pendulum models" used to describe nonlinear dynamic magnetic effects.

Relationship Between The Linear Ringing Frequencies In 3he-A And 3he-B Near The Polycritical Point, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

New measurements of parallel ringing in a quasi-ideal geometry for ³He-B near the temperature and pressure of the polycritical point suggest f_B²/f_A²∼5/2, where f_B and f_A are the linear parallel-ringing frequencies at a given temperature near T_c. This result approaches the prediction of theory using the Anderson-Brinkman-Morel and Balian-Werthamer states to describe ³He-A and ³He-B, respectively, and hence the results of Osheroff at melting pressure, but disagrees with earlier observations at pressures near the polycritical point.

Experiments On Dynamic Parallel Magnetism In Superfluid 3he, Richard A. Webb, R. L. Kleinberg, J. C. Wheatley

Faculty Publications

Observations are reported of the ringing of parallel magnetization in superfluid ³He when an incremental magnetic field parallel to a steady field is suddenly turned off.

Observation Of A Second-Order Phase Transition And Its Associated P - T Phase Diagram In Liquid He3, Richard A. Webb, T. J. Greytak, R. T. Johnson, J. C. Wheatley

Faculty Publications

A specific-heat "discontinuity" is observed in liquid He³ from 241 lb/in.2 to the melting pressure in the temperature range 2-3 mK.

Magnetic And Thermometric Properties Of Na3[Ce(C7h3no4)3] ·15h2o In The Millikelvin Range, Richard A. Webb, J. C. Wheatley

Faculty Publications

Measurements of the 16-Hz susceptibility of a powdered Na₃[Ce(C₇H₃NO₄)₃] · 15H₂O (CDP) sample, in the shape of a right-circular cylinder with diameter equal to height, have been made as a function of the Johnson noise temperature T_J of a resistor in the range 2 to 20 mK. Pure liquid ³He was used for thermal contact between the CDP and the noise thermometer in a demagnetization cell. The results are compared with similar data for cerium magnesium nitrate (CMN). CDP appears, like CMN, to have an anomalously …

Neuron-Proton Scattering At 23.6 Mev, Jerome G. Beery

Physics & Astronomy ETDs

The angular distribution for neutron-proton scattering was measured at a neutron energy of m3.6 MeV. The measurement was made using the Los Alamos Variable Energy Cyclotron and a liquid hydrogen bubble chamber. The angular distribution was normalized to a total n-p cross section of 408 mb.

The Diffraction Of Polarized Light From A Laser By A Straight Edge, Robert Lawrence Berger

Physics & Astronomy ETDs

The purpose of this experiment was to determine the effect of the polarized light from a highly coherent light source on the diffraction pattern of a metallic straight edge.

Fast Neutron Induced Fission Of U238, Michael J. Bennett

Physics & Astronomy ETDs

This work describes an experimental study of the energetics of the fission of U²³⁸ performed with solid state detectors. The fissions were produced by fission-spectrum neutrons from a reactor. The procedure used for calibrating the detector response is described and the effects of some experimental uncertainties, such as pulse height defect and neutron emission, are discussed.

Absorbance Of The Oh Radical In A Specific Wavelength Interval Near 309a, Paul F. Bird

Physics & Astronomy ETDs

The absorbance of the OH radical as a function of optical density was studied by computing the absorbance for an incident radiation in the wavelength interval 3089A-3097A. The absorbance was studied for 3 different temperatures and various values of the parameters specifying the line shapes and magnitude of the spectral absorption coefficient.

Characteristics And Calibration Of A Large Liquid Scintillator, James R. Barcus

Physics & Astronomy ETDs

It is the purpose of this thesis to present in some detail the method and results of the calibration -- in particular, the determination of the single particle pulse height which is crucial to any meaningful interpretation of the observational data.

On The Relation Between The Cosmic Ray Air Shower Spectrum And The Pulse Height Spectrum Of A Large Scintillator, Robert T. Barton

Physics & Astronomy ETDs

The purpose of this paper is to study other lateral distribution functions proposed by various authors, to select an alternative to the one used previously, to repeat the calculations of the required quantities using the alternative function, and to comment on the relative merits of the different choices. Since an empirical formula was used in the original work it seemed desirable to use a theoretical relation for comparison if a suitable one were available.

2. The Theory Of Special Relativity, Robert L. Bloom, Basil L. Crapster, Harold L. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section XX: Meaning in the Physical Sciences

Albert Einstein (1879-1955) published his first work on relativity in 1905, the same year in which he published remarkable papers on Brownian motion and the photoelectric effect. At the time he did this work, he was a patent examiner in the Swiss Patent Office. He was awarded the Nobel Prize for physics in 1921 "for his services to the theory of physics, and especially for his discovery of the law of the photoelectric effect." He became a professor of physics at several German universities, and in 1916, he took a position at the Kaiser Wilhelm Institute in Berlin.

As the …

5. Newton, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section VIII: The Development of Modern Science

Isaac Newton (1642-1727) was born and educated in England. He attended Trinity College, Cambridge, and there found the inspiration for his prodigious work that was to synthesize and extend the labors of Copernicus, Galileo, Kepler, and others beyond the wildest dreams of any of them. Newton was the intellectual giant who set the direction of the physical sciences on the paths they were to follow undeviatingly into the twentieth century. [excerpt]

1. The Problem, Robert L. Bloom, Basil L. Crapster, Harold L. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section XX: Meaning in the Physical Sciences

Newton's laws of motion and their associated definitions encountered their first difficulty near the middle of the nineteenth century.

Newton had designed his theory to describe the behavior of matter in space and time by inventing a relationship between the force on a body and the resulting change in motion of the body. Such a description of nature came to be called mechanical, and a large part of physicists' efforts were directed toward reducing all aspects of physics to mechanics. These efforts were rewarded magnificently in the fields of heat, electricity, and sound, in addition to astronomy and other more …

The Motion Of A Charged Particle In Homogenous Time-Varying Magnetic Field, Thomas R. Bates

Physics & Astronomy ETDs

This paper will discuss the motion of a non-relativistic, non-radiating charged particle in an infinite homogeneous magnetic field which varies linearly with time. We shall assume the motion to be confined to a plane perpendicular to the magnetic field.

Diffuse Reflection Of Light, Francis L. Bentsen

Physics & Astronomy ETDs

This thesis describes an attempt to determine the feasibility of measuring the ozone content in the air by absorption of light over a long path.

A Demonstration Of Various Procedures Used To Interest And Help Pupils To Understand Physics, O. M. Bjeldanes

Journal of the Minnesota Academy of Science

No abstract provided.

Modern Physics, Charles L. Critchfield

Journal of the Minnesota Academy of Science

No abstract provided.

The Intensity Of Zodiacal Light, Allan F. Beck

Physics & Astronomy ETDs

The study of the intensities measured in the region of the zodiacal light, the second most important contributor to this light of the night sky after starlight has been subtracted, is the purpose of this paper.

Radio And A Public Address System For The High School, Kenneth H. Westlake

University of the Pacific Theses and Dissertations

All the findings and knowledge of electricity and magnetism are not new; even the Greeks as far back as 600 B. C. knew something about these forces. As time went on the facts increased.

After the experiments of Faraday, Maxwell, Hertz and such men as these, electricity and magnetism became a vital part of human life and endeavor. Within the last twenty-five years the advances in electricity have been very rapid. The action of the electric current is a vital part of many developments and is helping to make human life more enjoyable and interesting.

Almost all schools today are …

Scholasticism An Intellectual Basis And Unifying Principle Of Modern Science, Alice V. Johnson

Electronic Theses and Dissertations

Amid the almost uninterrupted disintegration of systems during the last three centuries, the philosophy of St. Thomas has alone been able to stand the shock of criticism; it alone has proved sufficiently solid and comprehensive to serve as an intellectual basis and unifying principle for all the new facts and phenomena brought to light by modern science.

Some Contributions Of Pure Math To Science, Herbert B.E. Case

Student and Lippitt Prize Essays

An examination of the connection between math and science through discoveries in the subjects of astronomy, mechanics, physics and chemistry.