Two-pion production reactions in proton–proton collisions have been studied using the PROMICE/ WASA detector and an internal cluster gas-jet target at the CELSIUS storage ring in Uppsala. The total ...cross sections for the
pp→ppπ
+π
−
,
pp→ppπ
0π
0
and the
pp→pnπ
0π
+
reactions are presented at beam energies ranging from 650 to 775 MeV. An isospin analysis of the amplitudes involved in these three reactions indicates that the excitation of the
N
∗(1440)
followed by direct two pion emission can be the most important amplitude when allowed. However, large contributions from other production mechanisms must also be prevalent to explain the large
pp→pnπ
0π
+
cross section. The data are compared to an extensive model including non-resonant as well as resonant production via
N
∗
and
Δ excitation.
Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized $\vec n$p scattering performed in the energy region of ...the d* (2380) dibaryon resonance covering the range of beam energies Tn = 0.98 - 1.29 GeV (√ s = 2.32 - 2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process dp → np + pspectator. In this way the np differential cross section σ (Θ) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power Ay (Θ) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled 3D3 - 3G3 waves.
The new DAQ system for WASA at COSY Kleines, H.; Zwoll, K.; Wustner, P. ...
IEEE transactions on nuclear science,
06/2006, Letnik:
53, Številka:
3
Journal Article
Recenzirano
Wide angle shower apparatus (WASA), a detector for charged and neutral particles is currently operated at the CELSIUS storage ring by TSL, Uppsala University. It shall be transferred to the Cooler ...Synchrotron (COSY) at Forschungszentrum Julich (FZJ) after the anticipated shutdown of CELSIUS in summer 2005. For operation in Julich a new DAQ system is being developed, which conforms to the third generation of the DAQ systems at COSY. This comprises new readout electronics based on an optimized parallel bus with LVDS technology and FPGA-controlled event and buffer management, a synchronization system and a high speed optical link to the readout computer. Architecture of the new DAQ system and the technical issues of subsystems are presented.
For the operation of the WASA (Wide Angle Shower Apparatus) detector system at the Cooler Synchrotron COSY in Forschungszentrum Julich (FZJ) a new DAQ system has been developed, which conforms to the ...third generation of the DAQ systems at COSY. This comprises new readout electronics based on an optimized parallel bus with LVDS technology and FPGA-controlled event and buffer management. The new DAQ system has been successfully commissioned in autumn 2006. Further developments aiming at performance optimizations are in progress. The implementation status is presented and performance issues are discussed.
The differential cross section for the H-1(d, pp)n breakup reaction at deuteron beam energy of 340 MeV has been measured with the use of the WASA detector at COSY-Jillich. The set of proton-proton ...coincidences registered at the Forward Detector has been analyzed on a dense grid of kinematic variables, giving in total around 5600 data points. The cross-section data are compared to theoretical predictions based on the state-ofthe-art nucleon-nucleon potentials, combined with a three-nucleon force or the Coulomb interaction or carried out in a relativistic regime.
The pp → ppη reaction has been measured at six energies close to threshold, from 1258 MeV to 1352 MeV, using an internal cluster gas jet target in the CELSIUS storage ring. The η is detected through ...its decay photons, in an array of CsI detectors, and the forward-going protons are detected in a plastic scintillator spectrometer. A complete event reconstruction is obtained at the higher energies in the measured interval. The new data, together with earlier data, give an accurate determination of the energy dependence close to threshold. The influence of the η-proton FSI is seen in the total cross section data as well as in a Dalitz plot of the η-p invariant mass distributions.
The WASA-at-COSY experiment has collected 3 x 10(7) events with eta mesons produced via the reaction pd -> He-3 eta at T = 1.0 GeV. Using this data set, we evaluate the branching ratios of the ...decays eta -> pi(+)pi(-)gamma, eta -> e(+)e(-)gamma, eta -> pi(+)pi(-)e(+)e(-), and eta -> e(+)e(-)e(+)e(-). The branching ratios are normalized to the eta -> pi(+)pi(-) pi(0) decay. In addition an upper limit on a CP-violating asymmetry in eta -> pi(+)pi(-)e(+)e(-) is extracted.
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