1,657 research outputs found
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
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
Search for eta-mesic helium using the WASA-AT-COSY detector
We conduct a search for the 4He-eta bound state with the WASA-at-COSY
facility via the measurement of the excitation function for the reaction
dd->3Heppi-. In first experiment performed in June 2008, we used COSY deuteron
beam with a slowly ramped beam momentum corresponding to a variation of the
excess energy for the 4He-eta system from -51.4 MeV to 22 MeV. Here we report
on the status of the measurement and the data evaluation.Comment: Presented at Symposium on Meson Physics: extended COSY-11
collaboration meeting, Cracow, Poland, 1-4 Oct 2008, 8 pages, 5 figures
Search for the eta-mesic Helium bound state with the WASA-at-COSY facility
We performed a search for 4He-eta bound state 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 dd -> 3Henpi0 and dd ->
3Heppi- reactions by the measurement of the excitation functions in the
vicinity of the {\eta} production threshold. This paper presents the
experimental method and the preliminary results of the data analysis for dd ->
3Henpi0 process.Comment: Proceedings from the 12th International Conference on Nucleus-Nucleus
Collisions (NN2015), Catania 2015, June 21-2
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
Search for eta-mesic Helium with the WASA-at-COSY detector
A search for the 4He-eta bound state via exclusive measurement of the
excitation function for the dd->3Heppi- reaction, was performed at the Cooler
Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were
taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c
crossing the kinematic threshold for the eta production in the dd -> 4He-eta
reaction at 2.336 GeV/c. The corresponding excess energy in the 4He-eta system
varied from -51.4 MeV to 22 MeV. The shape of the excitation function for the
dd -> 3Heppi- was examined. No signal of the 4He-eta bound state was observed
in the excitation function.Comment: 4 pages, 5 figures, to appear in proceedings of MESON201
Feasibility of ortho-positronium lifetime studies with the J-PET detector in context of mirror matter models
We discuss the possibility to perform the experimental searches of invisible
decays in the ortho-positronium system with the J-PET detectorComment: 10 pages, 2 figure
Determination of the eta'-proton scattering length in free space
Taking advantage of both the high mass resolution of the COSY-11 detector and
the high energy resolution of the low-emittance proton-beam of the Cooler
Synchrotron COSY we determine the excitation function for the pp --> pp eta'
reaction close-to-threshold. Combining these data with previous results we
extract the scattering length for the eta'-proton potential in free space to be
Re(a_{p eta'}) = 0+-0.43 fm and Im(a_{p eta'}) = 0.37(+0.40)(-0.16) fm.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev. Let
Production and detection of atomic hexadecapole at Earth's magnetic field
Anisotropy of atomic states is characterized by population differences and
coherences between Zeeman sublevels. It can be efficiently created and probed
via resonant interactions with light, the technique which is at the heart of
modern atomic clocks and magnetometers. Recently, nonlinear magneto-optical
techniques have been developed for selective production and detection of higher
polarization moments, hexadecapole and hexacontatetrapole, in the ground states
of the alkali atoms. Extension of these techniques into the range of
geomagnetic fields is important for practical applications. This is because
hexadecapole polarization corresponding to the Zeeman coherence,
with maximum possible for electronic angular momentum and
nuclear spin , is insensitive to the nonlinear Zeeman effect (NLZ). This
is of particular interest because NLZ normally leads to resonance splitting and
systematic errors in atomic magnetometers. However, optical signals due to the
hexadecapole moment decline sharply as a function of magnetic field. We report
a novel method that allows selective creation of a macroscopic long-lived
ground-state hexadecapole polarization. The immunity of the hexadecapole signal
to NLZ is demonstrated with F=2 Rb atoms at Earth's field.Comment: 4 pages, 5 figure
Search for the 3He-eta bound state at COSY-11
We have measured excitation function for dp -> ppp_pi- reaction near the eta
production threshold. We observe an enhancement of the counting rate above the
threshold which can originate from the production of the eta meson in the
reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He
nucleus leading to creation of the p_pi- pair.Comment: Presented at 10th International Workshop on Meson Production,
Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 2008, 4
pages, 4 figures,references adde
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