162 research outputs found
The HADES Tracking System
The tracking system of the dielectron spectrometer HADES at GSI Darmstadt is
formed out of 24 low-mass, trapezoidal multi-layer drift chambers providing in
total about 30 square meter of active area. Low multiple scattering in the in
total four planes of drift chambers before and after the magnetic field is
ensured by using helium-based gas mixtures and aluminum cathode and field
wires. First in-beam performance results are contrasted with expectations from
simulations. Emphasis is placed on the energy loss information, exploring its
relevance regarding track recognition.Comment: 6 pages, 4 figures, presented at the 10th Vienna Conference on
Instrumentation, Vienna, February 2004, to be published in NIM A (special
issue
A versatile method for simulating pp -> ppe+e- and dp -> pne+e-p_spec reactions
We have developed a versatile software package for the simulation of
di-electron production in and collisions at SIS energies. Particular
attention has been paid to incorporate different descriptions of the Dalitz
decay via a common interface. In addition, suitable
parameterizations for the virtual bremsstrahlung process
based on one-boson exchange models have been implemented. Such simulation tools
with high flexibility of the framework are important for the interpretation of
the di-electron data taken with the HADES spectrometer and the design of
forthcoming experiments
The interaction studied via femtoscopy in p + Nb reactions at
We report on the first measurement of and correlations via
the femtoscopy method in p+Nb reactions at , studied with the High Acceptance Di-Electron Spectrometer
(HADES). By comparing the experimental correlation function to model
calculations, a source size for pairs of and a slightly
smaller value for of is extracted.
Using the geometrical extent of the particle emitting region, determined
experimentally with correlations as reference together with a source
function from a transport model, it is possible to study different sets of
scattering parameters. The correlation is proven sensitive to
predicted scattering length values from chiral effective field theory. We
demonstrate that the femtoscopy technique can be used as valid alternative to
the analysis of scattering data to study the hyperon-nucleon interaction.Comment: 12 pages, 11 figure
An upper limit on hypertriton production in collisions of Ar(1.76 AGeV)+KCl
A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES
is used to search for a hypertriton signal. An upper production limit per
centrality-triggered event of x on the level is
derived. Comparing this value with the number of successfully reconstructed
hyperons allows to determine an upper limit on the ratio
, which is confronted with statistical and
coalescence-type model calculations
Deep sub-threshold production in Ar+KCl reactions at 1.76A GeV
We report first results on a deep sub-threshold production of the doubly
strange hyperon in a heavy-ion reaction. At a beam energy of 1.76A GeV
the reaction Ar+KCl was studied with the High Acceptance Di-Electron
Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity
sample was collected, allowing for the investigation of the decay channel
. The deduced production
ratio of is significantly larger
than available model predictions.Comment: 4 pages, including 4 figure
Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy
We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p
reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES
experiment at GSI. This report evaluates the contribution of resonances like
Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the
Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to
the experimental data in several angular distributions and it shows itself as
suitable to evaluate the acceptance corrections properly.Comment: 15 pages, 5 figure
Study of the quasi-free reaction with a deuterium beam at 1.25 GeV/nucleon
The tagged quasi-free reaction has been studied
experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI
at a deuteron incident beam energy of 1.25 GeV/nucleon ( 2.42
GeV/c for the quasi-free collision). For the first time, differential
distributions for production in collisions have been
collected in the region corresponding to the large transverse momenta of the
secondary particles. The invariant mass and angular distributions for the
reaction are compared with different models.
This comparison confirms the dominance of the -channel with
contribution. It also validates the changes previously introduced in the
Valencia model to describe two-pion production data in other isospin channels,
although some deviations are observed, especially for the
invariant mass spectrum. The extracted total cross section is also in much
better agreement with this model. Our new measurement puts useful constraints
for the existence of the conjectured dibaryon resonance at mass M 2.38
GeV and with width 70 MeV
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