Molecular Beams

Contains reports on one research project.Joint Services Electronics Program (Contract DAAB07-71-C-0300

The development of ultrahigh and extreme high vacuum technology for physics research

Over the last 50 years increasingly larger and more sophisticated devices have been designed and put into operation for the study of particle and nuclear physics, magnetic confinement of high-temperature plasmas for thermonuclear fusion research, and gravity wave observatories based on laser interferometers. The evolution of these devices has generated many developments in ultrahigh and extreme high vacuum technology that were required for these devices to meet their operational goals. The technologies that were developed included unique ultrahigh vacuum vessel structures, ultrahigh vacuum compatible materials, surface conditioning techniques, specialized vacuum pumps and vacuum diagnostics. Associated with these technological developments are scientific advancements in the understanding of outgassing limits of UHV-compatible materials and particle-induced desorption effects

Molecule Microscopy

Contains reports on two research projects.Joint Services Electronics Program (Contract DAABO7-74-C-0630)National Institutes of Health (Grant 5 PO1 HL14322-04

Molecule Microscopy

Contains reports on three research projects.Joint Services Electronics Program (Contract DAAB07-71-C-0300)National Institutes of Health (Grant 5 PO1 HL14332-03)Environmental Measurements Project Laboratory grant from the Dean of Science, M.I.T

Electron Optics

Contains reports on one research project.Joint Services Electronics Program (Contract DAAB07-74-C-0630

Vacuum Polarization and the Electric Charge of the Positron

We show that higher-order vacuum polarization would contribute a measureable net charge to atoms, if the charges of electrons and positrons do not balance precisely. We obtain the limit $|Q_e+Q_{\bar e}| < 10^{-18} e$ for the sum of the charges of electron and positron. This also constitutes a new bound on certain violations of PCT invariance.Comment: 9 pages, 1 figure attached as PostScript file, DUKE-TH-92-38. Revised versio

Molecular Beams

Contains reports on three research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

Electric charge quantization without anomalies?

In gauge theories like the standard model, the electric charges of the fermions can be heavily constrained from the classical structure of the theory and from the cancellation of anomalies. We argue that the anomaly conditions are not quite as well motivated as the classical constraints, since it is possible that new fermions could exist which cancel potential anomalies. For this reason we examine the classically allowed electric charges of the known fermions and we point out that the electric charge of the tau neutrino is classically allowed to be non-zero. The experimental bound on the electric charge of the tau neutrino is many orders of magnitude weaker than for any other known neutrino. We discuss possible modifications of the minimal standard model such that electric charge is quantized classically.Comment: 10 McGill/93-3

Molecular Beams

Contains research objectives and reports on five research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Institutes of Health (Grant 5 S05 FR07046-06)Public Health Service Research Grant 1 P01 HL14322-01 from the National Heart and Lung Institute to the Harvard-M. I. T. Program in Health Services and Technolog

Constraints on the Electrical Charge Asymmetry of the Universe

We use the isotropy of the Cosmic Microwave Background to place stringent constraints on a possible electrical charge asymmetry of the universe. We find the excess charge per baryon to be $q_{e-p}<10^{-26}e$ in the case of a uniform distribution of charge, where $e$ is the charge of the electron. If the charge asymmetry is inhomogeneous, the constraints will depend on the spectral index, $n$, of the induced magnetic field and range from $q_{e-p}<5\times 10^{-20}e$ ($n=-2$) to $q_{e-p}<2\times 10^{-26}e$ ($n\geq 2$). If one could further assume that the charge asymmetries of individual particle species are not anti-correlated so as to cancel, this would imply, for photons, $q_\gamma< 10^{-35}e$; for neutrinos, $q_\nu<4\times10^{-35}e$; and for heavy (light) dark matter particles $q_{\rm dm}<4\times10^{-24}e$ ($q_{\rm dm}<4\times10^{-30}e$).Comment: New version to appear in JCA