2,129 research outputs found
Lunar surface holography experiment instrument feasibility demonstration Final report, 27 Jul. - 30 Nov. 1970
Prototype holocamera and playback system for lunar surface holography experimen
Single Atom Detection With Optical Cavities
We present a thorough analysis of single atom detection using optical
cavities. The large set of parameters that influence the signal-to-noise ratio
for cavity detection is considered, with an emphasis on detunings, probe power,
cavity finesse and photon detection schemes. Real device operating restrictions
for single photon counting modules and standard photodiodes are included in our
discussion, with heterodyne detection emerging as the clearly favourable
technique, particularly for detuned detection at high power.Comment: 11 pages, 8 figures, submitted to PRA, minor changes in Secs. I and
IVD.2, and revised Fig.
A detector for continuous measurement of ultra-cold atoms in real time
We present the first detector capable of recording high-bandwidth real time
atom number density measurements of a Bose Einstein condensate. Based on a
two-color Mach-Zehnder interferometer, our detector has a response time that is
six orders of magnitude faster than current detectors based on CCD cameras
while still operating at the shot-noise limit. With this minimally destructive
system it may be possible to implement feedback to stabilize a Bose-Einstein
condensate or an atom laser.Comment: 3 pages, 3 figures, submitted to optics letter
Decisive Search for a Diquark-Antidiquark Meson with Hidden Strangeness
Diquark-antidiquark states are expected to exist as a natural complement of
mesons and baryons. Although they were predicted long ago, and some candidates
were found experimentally, none has, as yet, been reliably identified. We
suggest that the search for the so-called -meson in reactions such as
photoproduction and should provide a decisive way to settle this issue. Estimates of the
cross sections are given using present experimental information on the C-meson
and assuming its diquark-antidiquark structure. Sizable cross sections are
predicted (of the order of 0.1 b for photoproduction and of the order of
0.1 mb for at the maximum with an insignificant background). Failure to
find this kind of signal would imply that the C-meson is {\it not} a
diquark-antidiquark state.Comment: 9 pages in LATex + 6 figs. (available from authers upon request),
IUHET-269/9
Quantum projection noise limited interferometry with coherent atoms in a Ramsey type setup
Every measurement of the population in an uncorrelated ensemble of two-level
systems is limited by what is known as the quantum projection noise limit.
Here, we present quantum projection noise limited performance of a Ramsey type
interferometer using freely propagating coherent atoms. The experimental setup
is based on an electro-optic modulator in an inherently stable Sagnac
interferometer, optically coupling the two interfering atomic states via a
two-photon Raman transition. Going beyond the quantum projection noise limit
requires the use of reduced quantum uncertainty (squeezed) states. The
experiment described demonstrates atom interferometry at the fundamental noise
level and allows the observation of possible squeezing effects in an atom
laser, potentially leading to improved sensitivity in atom interferometers.Comment: 8 pages, 8 figures, published in Phys. Rev.
Cold atom gravimetry with a Bose-Einstein Condensate
We present a cold atom gravimeter operating with a sample of Bose-condensed
Rubidium-87 atoms. Using a Mach-Zehnder configuration with the two arms
separated by a two-photon Bragg transition, we observe interference fringes
with a visibility of 83% at T=3 ms. We exploit large momentum transfer (LMT)
beam splitting to increase the enclosed space-time area of the interferometer
using higher-order Bragg transitions and Bloch oscillations. We also compare
fringes from condensed and thermal sources, and observe a reduced visibility of
58% for the thermal source. We suspect the loss in visibility is caused partly
by wavefront aberrations, to which the thermal source is more susceptible due
to its larger transverse momentum spread. Finally, we discuss briefly the
potential advantages of using a coherent atomic source for LMT, and present a
simple mean-field model to demonstrate that with currently available
experimental parameters, interaction-induced dephasing will not limit the
sensitivity of inertial measurements using freely-falling, coherent atomic
sources.Comment: 6 pages, 4 figures. Final version, published PR
Quark-Hadron Duality and Parity Violating Asymmetry of Electroweak Reactions in the Delta Region
A dynamical model of electroweak pion production reactions in the Delta(1232)
region has been extended to include the neutral current contributions for
examining the local Quark-Hadron Duality in neutrino-induced reactions and for
investigating how the axial N-Delta form factor can be determined by the parity
violating asymmetry of N(\vec{e},e') reactions. We first show that the recent
data of (e,e') structure functions F_1 and F_2, which exhibit the Quark-Hadron
Duality, are in good agreement with our predictions. For possible future
experimental tests, we then predict that the structure functions F_1, F_2, and
F_3 for (\nu,e) and (\nu,\nu') processes also show the similar Quark-Hadron
Duality. The spin dependent structure functions g_1 and g_2 of (e,e') have also
been calculated from our model. It is found that the local Quark-Hadron Duality
is not seen in the calculated g_1 and g_2, while our results for g_1 and some
polarization observables associated with the exclusive p(\vec{e},e' pi) and
\vec{p}(\vec{e},e' pi) reactions are in reasonably good agreement with the
recent data. In the investigation of parity violating asymmetry A of
N(\vec{e},e') reactions, it is found that the non-resonant contribution is
small at the Delta peak and a measurement of A can be used to distinguish two
previously determined axial N-Delta transition form factors. The predicted
asymmetry A are also compared with the Parton Model predictions for future
experimental investigations of Quark-Hadron Duality.Comment: 28 pages, 19 figures v2; figures and references adde
Effects of Flavor-dependent Annihilation on the Mixing Angle of the Isoscalar Octet-Singlet and Schwinger's Nonet Mass Formula
By incorporating the flavor-dependent quark-antiquark annihilation amplitude
into the mass-squared matrix describing the mixing of the isoscalar states of a
meson nonet, the new version of Schwinger's nonet mass formula which holds with
a high accuracy for the , , , and
nonets is derived and the mixing angle of isoscalar octet-singlet for these
nonets is obtained. In particular, the mixing angle of isoscalar octet-singlet
for pseudoscalar nonet is determined to take the value of , which
is in agreement with the value of deduced from a
rather exhaustive and up-to-date analysis of data. It is also pointed out that
the omission of the flavor-dependent annihilation effect might be a
factor resulting in the invalidity of Schwinger's original nonet mass formula
for pseudoscalar nonet.Comment: Latex, 7 page
Micro-canonical pentaquark production in \ee annihilations
The existence of pentaquarks, namely baryonic states made up of four quarks
and one antiquark, became questionable, because the candidates, i.e. the
peak, are seen in certain reactions, i.e. p+p collisions, but not in
others, i.e. \ee annihilations. In this paper, we estimate the production of
and in \ee annihilations at different
energies using Fermi statistical model as originally proposed in its
microcanonical form. The results is compared with that from pp collisions at
SPS and RHIC energies. We find that, if pentaquark states exist, the production
is highly possible in \ee annihilations. For example, at LEP energy
=91.2 GeV, both and yield more
than in pp collisions at SPS and RHIC energy.Comment: 7 pages 2 figure
- …