1,296 research outputs found
Response of Waterbirds to Salt Pond Enhancements and Island Creation in the San Francisco Bay
Historically, San Francisco Bay supported the largest salt pond complex on the Pacific coast of North America, and these areas have been used by large numbers of migrating and wintering waterbirds for more than a century. In 2003, salt ponds in the South San Francisco Bay were purchased with a goal of restoring 50-90% of the 6100 ha of former salt ponds to replace lost tidal marsh habitats. However, a major challenge for the restoration project has been maintaining the abundance of non-breeding waterbirds in a smaller footprint of managed ponds. Thus, in 2009-2010, Pond SF2 was enhanced with 30 islands of two different shapes and water control structures that provided muted tidal flows with shallow water depths predicted to benefit waterbirds. To assess how non-breeding waterbirds responded to these enhancements, a spatial grid (50 m x 50 m) was used to survey SF2 weekly from October to May 2010-2012, and examine waterbird use. Of the 262,932 non-breeding waterbirds observed, only 12-15% used the islands depending on tide. Island size, shape, or both predicted the presence or relative abundance of some foraging guilds, whereas island slope, perimeter, and distance to mudflat did not improve the model\u27s predictions of relative guild abundances. Results indicated that waterbirds were attracted to areas with shallow water depths; however, the constructed islands were not used by a large number of waterbirds
Combined analysis of the interaction using near threshold data
The final state interaction was investigated based on both the
invariant mass distributions measured at excess energies of Q = 10
and 28 MeV and the near threshold excitation function for the reaction. The final state enhancement factor was
parametrized using the effective range expansion. The effective range of the
interaction was estimated to be: and , and the
determined real and imaginary parts of the scattering length amount
to: and .Comment: 5 pages, 3 figures, article accepted for publication in Phys. Rev.
Test of charge conjugation invariance in the decay of the eta meson into pi(+)pi(-)pi(0)
In this work we present the preliminary results of the analysis of the pp->pp
eta(->pp pi(+)pi(-)pi(0) reaction aiming to test the charge conjugation
symmetry C in strong interactions. Based on approximately identified
eta->pi(+)pi(-)pi(0) decay events we have extracted asymmetry parameters
sensitive to C symmetry violation for different isospin values of the final
state and we have established that all are consistent with zero within the
obtained accuracy.Comment: MESON2012 - 12th International Workshop on Meson Production,
Properties and Interactio
Multimeson production in pp interactions as a background for eta and eta' decays
Multimeson production in pp interactions comprises important background for
eta, omega and eta' mesons production experiments and for the studies of their
decays planned with WASA detector at COSY. The available information about the
reactions is summarized and the need for efforts to describe the processes is
stressed.Comment: Proceedings of MENU07 Conference Julich, Germany 200
Search for the 4He-eta bound state in dd->(4He-eta)_{bound}->3He n pi0 and dd->(4He-eta)_{bound}->3He p pi- reactions with the WASA-at-COSY facility
In November 2010, the search for the 4He-{\eta} bound state was per formed
with high statistics and high acceptance with the WASA-at-COSY facility using a
ramped beam technique. The signature of eta - mesic nuclei is searched for in
the measured excitation functions for the two reaction channels: dd ->3He n pi0
and dd ->3He p pi- near the eta production threshold. This report includes the
description of the experimental method and the status of the data analysis.Comment: 4 page
Close to threshold eta' meson production in proton-proton collisions at COSY-11
Intensive quest for the eta and eta' bound states is currently ongoing at
both theoretical and experimental levels e.g. at COSY, ELSA, GSI, JINR, JPARC,
LPI, and MAMI. These studies were already supported by data provided by the
COSY-11 collaboration including determination of the total width of the eta'
meson. In addition, the first rough estimation of the eta'-N interaction from
the excitation function of the cross section for the pp-->pp eta' reaction was
also performed. Recent precise measurement in this field from the COSY-11
experiment allows to summarize results on the eta' meson production cross
section in proton-proton collisions at COSY-11.Comment: 4 pages, 1 figure, presented at 13th International Workshop on Meson
Production, Properties and Interaction, Cracow, Poland, 29th May - 3rd June
201
Luminosity determination for the deutron-deutron reactions using free and quasi-free reactions with WASA-at-COSY detector
Two methods of the luminosity determination for the experiment performed by
WASA collaboration to search for - bound state are
presented. During the measurement the technique of continous change of the beam
momentum in one accelerator cycle (called ramped beam) was applied. This
imposes the requirement to determine not only the total integrated luminosity,
but also its variation as a function of the beam momentum.Comment: Symposium on Applied Nuclear Physics and Innovative Technologies,
Krakow (Poland), 24-27.09.201
Study of the eta meson production with polarized proton beam
The pp-> pp eta reaction was investigated at excess energies of 15 MeV and 72
MeV using the azimuthally symmetric WASA detector and a polarized proton beam
of the Cooler Synchrotron COSY. The aim of the studies is the determination of
partial wave contributions to the production process of the eta meson in
nucleon-nucleon collisions. Here we present preliminary results of the
extraction of the position of the interaction region with respect to the WASA
detector and preliminary results on the degree of polarization of the COSY
proton beam used in the experiment.Comment: Invited talk at the Second International Symposium on Mesic Nuclei,
Cracow, Poland, September 22-25 201
Upper limits for the production of the eta-mesic Helium in the dd ->3Henpi0 and dd -> 3Heppi- reactions
We performed a search for 4He-eta bound state in dd -> 3Henpi0 and dd ->
3Heppi- reactions with the WASA-at-COSY facility using a ramped beam technique.
The measurement was carried out with high statistics and high acceptance. The
signature of eta-mesic nuclei was searched for by the measurement of the
excitation functions in the vicinity of the eta production threshold for each
of the considered channels. We did not observe the narrow structure which could
be interpreted as a bound state. The preliminary upper limits of the total
cross sections for the bound state production and decay varies from 21 nb to 36
nb for the dd -> 3Henpi0 channel, and from 5 nb to 9 nb for the dd -> 3Heppi-
channel for the bound state width ranging from 5 to 50 MeV.Comment: Acta Phys. Polon. B 201
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