4,481 research outputs found
The Possible Detection of Dark Energy on Earth Using Atom Interferometry
This paper describes the concept and the beginning of an experimental
investigation of whether it is possible to directly detect dark energy density
on earth using atom interferometry. The concept is to null out the
gravitational force using a double interferometer. This research provides a
non-astronomical path for research on dark energy. The application of this
method to other hypothetical weak forces and fields is also discussed. In the
the final section I discuss the advantages of carrying out a dark energy
density search in a satellite in earth orbit where more precise nulling of
gravitational forces can be achieved
Hard breakup of the deuteron into two Delta-isobars
We study high energy photodisintegration of the deuteron into two
-isobars at large center of mass angles within the QCD hard
rescattering model (HRM). According to the HRM, the process develops in three
main steps: the photon knocks the quark from one of the nucleons in the
deuteron; the struck quark rescatters off a quark from the other nucleon
sharing the high energy of the photon; then the energetic quarks recombine into
two outgoing baryons which have large transverse momenta. Within the HRM, the
cross section is expressed through the amplitude of scattering which we evaluated based on the quark-interchange
model of hard hadronic scattering. Calculations show that the angular
distribution and the strength of the photodisintegration is mainly determined
by the properties of the
scattering. We predict that the cross section of
the deuteron breakup to is 4-5 times larger than that
of the breakup to the channel. Also, the angular
distributions for these two channels are markedly different. These can be
compared with the predictions based on the assumption that two hard
-isobars are the result of the disintegration of the preexisting
components of the deuteron wave function. In this case, one
expects the angular distributions and cross sections of the breakup in both and channels to be similar.Comment: 17 pages, 3 figure
A New Method for Searching for Free Fractional Charge Particles in Bulk Matter
We present a new experimental method for searching for free fractional charge
in bulk matter; this new method derives from the traditional Millikan liquid
drop method, but allows the use of much larger drops, 20 to 100 mm in diameter,
compared to the traditional method that uses drops less than 15 mm in diameter.
These larger drops provide the substantial advantage that it is then much
easier to consistently generate drops containing liquid suspensions of powdered
meteorites and other special minerals. These materials are of great importance
in bulk searches for fractional charge particles that may have been produced in
the early universe.Comment: 17 pages, 5 figures in a singl PDF file (created from WORD Doc.).
Submitted to Review of Scientific Instrument
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 particles per nucleon with 95%
confidence.Comment: 10 pages,LaTeX, 4 PS figures, submitted to PR
The Practice of Experimental Physics - Recollections, Reflections, and Interpretations
This article is based on Martin L. Perl’s Nobel Prix 1995 paper, “Reflections on the Discovery of the Tau Lepton,” and is supplemented by excerpts from his presentation, “Reflections on Experimental Science,” to an audience of mainly young scientists at Los Alamos National Laboratory on June 29, 1999. In both documents, Perl reflects on almost 50 years of experience in experimental science to pass on what he has learned, particularly to young people who are beginning scientific research
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