The tagged quasi-free np→npπ+π−np→npπ+π− 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 (View the MathML sources∼2.42 GeV/c for the quasi-free collision). For the first time, differential distributions of solid statistics for π+π−π+π− production in np 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 np→npπ+π−np→npπ+π− reaction are compared with different models. This comparison confirms the dominance of the t -channel with ΔΔ 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 π+π−π+π− 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 GeVM∼2.38 GeV and with width Γ∼70 MeVΓ∼70 MeV.
Retgem with polyvinylchloride electrodes Razin, V. I.; Reshetin, A. I.; Filippov, S. N.
Instruments and experimental techniques (New York),
09/2011, Letnik:
54, Številka:
5
Journal Article
Recenzirano
This paper presents a new design of Gas Electron Multiplier (GEM) based on electrodes made of polyvinylchloride plastic (PVC)-Resistive Electrode Thick GEM (RETGEM). Our device can operate with the ...gain up to 10
5
as a conventional GEM at low counting rates and as RPC (Resistive Plate Counter) in case of high counting rates without the transit to the violent sparks. The distinct feature of present RETGEM is the absent of the metal coating and lithographic technology for manufacturing of the protective dielectric rims. The electrodes made of PVC permit us to make the holes by a simple drilling machine. RETGEM-like detectors could be useful in many fields of application requiring a cheaper manufacturing and safer operation, for example, in large neutrino experiments, in TPC, RICH systems, etc.
We study the production of Σ±π∓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 Λ(1405), Σ(1385)0, Λ(1520), Δ(1232), N⁎ and K⁎0 to the Σ±π∓pK+ 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.
The main characteristics of the forward scintillation hodoscope and readout electronics of the high acceptance dielectron spectrometer (HADES) at GSI (Darmstadt, Germany) are presented. Methods for ...adjustment and amplitude-time calibration of hodoscope detectors using cosmic rays and results of measurements of the Au + Au reaction at a beam energy of 1.24 GeV/nucleon are described. The use of the forward hodoscope for tagging the
n
+
p
reaction by means of the deuteron beam incident on a liquid hydrogen target is discussed. A procedure for determining the reaction plane angle in event-by-event analysis of the Au + Au reaction data (at 1.24 GeV/nucleon) is presented.
We present an analysis of the hyperons Λ(1405) and Σ(1385)
+
for p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the
H
igh
A
cceptance
D
i-
E
lectron
S
pectrometer (HADES). A ...Λ(1405) signal could be reconstructed in both charged decay channels Λ(1405)→Σ
±
π
∓
. The obtained statistics of the Σ(1385)
+
signal allows also differential studies.
In given article preliminary results of the research of the electron multiplication in MPGD are presented at a high level of alpha-particles background. This work has expanded borders of ...understanding of the streamer mode nature. It is seen as a complex from electrostatic and electromagnetic interactions which begin with appearance of the precursor in plasma state. In an inter-electrode gap the plasma oscillations occur, accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with induced negative charge. With the release of this charge due to previously established conducting channel there is a strong current pulse, accompanied by the emission due to recombination of positive and negative ions and a thin cord or streamer derive. In the aim of the MPGD protection from the spark breakdown at a high level of the alpha-particle background the next gas composition from a buffer, cooling and electronegative components are offered: 70% He +28% CF4 +2% SF6.
The ageing of CsI film by exposure to air is discussed. Such exposures may take place during the transfer of a CsI photocathode from the evaporation vessel to the detector. The direct current (DC) ...was measured using a deuterium lamp for UV irradiation. It has been recorded as a function of the length of exposure to air for the case of small photocathodes. A 1h exposure was found to have no remarkable effect in comparison to 8 or 15min, but the current was decreased by 90% after 24h exposure. A simple technique for CsI evaporation has been developed.
Results on pp, π
+
π
+
, and π
−
π
−
intensity interferometry are reported for collisions of Ar+KCl at 1.76
A
GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at ...SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The ππ source radii are found significantly larger than the pp emission radius. The present radii do well complement the beam-energy dependences of Gaussian source radii of the collision system of size
A
+
A
≃ 40 + 40 . The pp source radius at fixed beam energy is found to increase linearly with the cube root of the number of participants. From this trend, a lower limit of the pp correlation radius is deduced.
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