arXiv subjects

M. L. Perl

Publications and source records attributed to M. L. Perl.

5 recordsLinked to original sources

arXiv1999

Search for Free Fractional Electric Charge Elementary Particles

We have carried out a direct search in bulk matter for free fractional electric charge elementary particles using the largest mass single sample ever studied - about 17.4 mg of silicone oil. The search used an improved and highly automated Millikan oil drop technique. No evidence for fractional charge particles was found. The concentration of particles with fractional charge more than 0.16e (e being the magnitude of the electron charge) from the nearest integer charge is less than $4.71\times10^{-22}$ particles per nucleon with 95% confidence.

hep-ex↗

arXiv1999

Certainty and Uncertainty in the Practice of Science: Electrons, Muons, and Taus

During the past one hundred years three related elementary particles - the electron, the muon, and the tau - were discovered by very different scientific techniques. The author, who received the Wolf Prize and the Nobel Prize for the discovery of the tau, uses this history to discuss certainty and uncertainty in the practice of science. While the emphasis is on the practice of scientific research, the paper also explains for the non-physicist some basic ideas in elementary particle science.

physics.hist-ph↗

arXiv1998

The Tau Lepton and the Search for New Elementary Particle Physics

This Fifth International WEIN Symposium is devoted to physics beyond the standard model. This talk is about tau lepton physics, but I begin with the question: do we know how to find new physics in the world of elementary particles? This question is interwoven with the various tau physics topics. These topics are: searching for unexpected tau decay modes; searching for additional tau decay mechanisms; radiative tau decays; tau decay modes of the W, B, and D; decay of the Z^0 to tau pairs; searching for CP violation in tau decay; the tau neutrino, dreams and odd ideas in tau physics; and tau research facilities in the next decades.

hep-ph↗

arXiv1997

Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials

The cross section for bremsstrahlung from highly relativistic particles is suppressed due to interference caused by multiple scattering in dense media, and due to photon interactions with the electrons in all materials. We present here a detailed study of bremsstrahlung production of 200 keV to 500 MeV photons from 8 and 25 GeV electrons traversing a variety of target materials. For most targets, we observe the expected suppressions to a good accuracy. We observe that finite thickness effects are important for thin targets.

hep-ex↗

arXiv1995

Measurement of Dielectric Suppression of Bremsstrahlung

In 1953, Ter-Mikaelian predicted that the bremsstrahlung of low energy photons in a medium is suppressed because of interactions between the produced photon and the electrons in the medium. This suppression occurs because the emission takes place over on a long distance scale, allowing for destructive interference between different instantaneous photon emission amplitudes. We present here measurements of bremsstrahlung cross sections of 200 keV to 20 MeV photons produced by 8 and 25 GeV electrons in carbon and gold targets. Our data shows that dielectric suppression occurs at the predicted level, reducing the cross section up to 75 percent in our data.

hep-ph↗