We present the first determination of the energy-dependent amplitudes of N⁎ resonances extracted from their decay in KΛ pairs in p+p→pK+Λ reactions. A combined Partial Wave Analysis of seven data ...samples with exclusively reconstructed p+p→pK+Λ events measured by the COSY-TOF, DISTO, FOPI and HADES Collaborations in fixed target experiments at kinetic energies between 2.14 to 3.5 GeV is used to determine the amplitude of the resonant and non-resonant contributions into the associated strangeness final state. The contribution of seven N⁎ resonances with masses between 1650 MeV/c2 and 1900 MeV/c2 for an excess energy between 0 and 600 MeV has been considered. The Σ–p cusp and final state interactions for the p–Λ channel are also included as coherent contributions in the PWA. The N⁎ contribution is found to be dominant with respect to the phase space emission of the pKΛ+ final state at all energies demonstrating the important role played by both N⁎ and interference effects in hadron–hadron collisions.
We report on the measurements of directed flow v1 and elliptic flow v2 for hadrons (π±, K±, KS0, p, ϕ, Λ and Ξ−) from Au+Au collisions at sNN=3GeV and v2 for (π±, K±, p and p‾) at 27 and 54.4GeV with ...the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3GeV the v2 at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the v1 slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative v2 and positive v1 slope at 3GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.
A Multi-strip Multi-gap RPC Barrel for Time-of-Flight Measurements Kiš, M.; Ciobanu, M.; Deppner, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2011, Letnik:
646, Številka:
1
Journal Article
Recenzirano
The FOPI detector
1 at the heavy-ion synchrotron SIS-18 at GSI in Darmstadt has upgraded part of its time-of-flight (ToF) system by adding a new sub-detector shell (called the MMRPC Barrel) that is ...made out of Multi-strip Multi-gap Resistive-Plate Counters (MMRPCs). The MMRPC Barrel has an active area of 5
m
2 covered by 2400 individual anode strips
2,3 which are read out at both ends by custom-designed electronics
4,5. With these multi-strip anodes we have obtained an enhanced detector granularity with 95% efficiency and a ToF resolution
σ
ToF
better than 90
ps which increases the identification limit for charged kaons up to laboratory momenta of at least 1
GeV/
c. In this paper we report on the design, construction and operational characteristics of the MMRPC Barrel and describe its performance during the first experiments.
Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive J / ψ at mid-rapidity in 0-100% p+Au collisions at s NN = 200 GeV is presented. Such ...effects are quantified utilizing the nuclear modification factor, R p Au , obtained by taking a ratio of J / ψ yield in p+Au collisions to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The differential J / ψ yield in both p+p and p+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the J / ψ R p Au is derived within the transverse momentum ( p T ) range of 0 to 10 GeV/c. A suppression of approximately 30% is observed for p T < 2 GeV/c, while J / ψ R p Au becomes compatible with unity for p T greater than 3 GeV/c, indicating the J / ψ yield is minimally affected by the CNM effects at high p T . Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong J / ψ suppression above 3 GeV/c is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured J / ψ R p Au , while their agreement with the J / ψ yields in p+p and p+Au collisions is worse.
Two dimensional position sensitive timing MGMSRPC prototypes were developed for the low polar angles of the CBM - TOF wall. Four MGMSRPC counters were arranged in a staggered geometrical ...configuration along the z direction, with overlap along and across the strips, in order to define a basic architecture for the inner zone of the CBM-TOF wall. This configuration was tested with mixed electron-pion beam at CERN-PS and with reaction products resulted from the heavy ion induced reactions at SIS18 - GSI Darmstadt and SPS - CERN. The performance of the basic architecture in conditions close to the ones expected for their operation in the inner zone o the CBM - TOF wall at SIS100 FAIR will be presented.
PDF
