Two fast interaction trigger systems based on fast detectors with MCP-PMTs and SiPMs readout have been developed for fixed target experiment Baryonic Matter at Nuclotron and collider experiment ...Multi-Purpose Detector at Laboratory of High Energy Physics, Joint Institute for Nuclear Research. These detectors provide the effective L0 trigger for nucleus–nucleus collisions and the start pulse T0 for TOF detectors with picosecond time resolution. Important requirement to the detectors is good operation in a strong magnetic field.
•L0 trigger systems for heavy ion experiments at JINR are described.•The MCP-PMTs and SiPMs are used for readout in Cherenkov and scintillation detectors.•The detectors operate in a strong magnetic field.•T0 pulse with picosecond time resolution is produced for TOF detectors.
Fast Cherenkov and scintillation detectors based on microchannel-plate photomultiplier tubes and silicon photomultipliers are being developed for application in the multi-purpose detector and ...baryonic matter at the Nuclotron experiments with the heavy ion beams at the Joint Institute for Nuclear Research. The aim of the detectors is the fast triggering of nucleus–nucleus collisions with high efficiency and to generate the start signal with picosecond time resolution for time-of-flight measurements. The detectors provide a time resolution better than 50 ps and can operate in the strong magnetic field of the experimental facilities.
Two modular Cherenkov detectors FFD and T0 are developed for MPD and BM@N projects at LHEP/JINR for study of Au + Au collisions. The aim of the detectors is production of a start signal for a TOF ...detector and an effective L0 trigger for the collisions. The detector module design, characteristics, and results of tests with a deuteron beam are discussed. The time resolution of the modules for a single high energy photon or charged hadron is σ
t
≈ 21–31 ps and it depends on method and electronics used.
We report a measurement of low-mass electron pairs observed in 158 GeV/nucleon Pb-Au collisions. The pair yield integrated over the range of invariant masses 0.2 ≤
m≤ 2.0 GeV/c
2 is enhanced by a ...factor of 3.5 ± 0.4 (stat) ± 0.9 (syst) over the expectation from neutral meson decays. As observed previously in S-Au collisions, the enhancement is most pronounced in the invariant-mass region 300-700 MeV/c
2. For Pb-Au we find evidence for a strong increase of the enhancement with centrality. In addition, we show that the enhancement covers a wide range in transverse momentum, but is largest at the lowest observed
p
⊥.
The High Acceptance DiElectron Spectrometer (HADES) has been recently commissioned at GSI Darmstadt. It has been designed to study hadron properties inside nuclear matter via measurements of ...dielectron decays in proton, pion and heavy ion induced reactions in
1
−
2
AGeV
energy range. We report first preliminary results on invariant masses of
e
+
e
−
pairs measured in
12C +
12C collisions at
E
=
2
AGeV
and compare them to simulations based on UrQMD transport model. In summary we present and discuss planned experiments.
During the 1996 lead run time, CERES has accumulated 42 million events, corresponding to a factor of 5 more statistics than in 1995 and 2.5 million events of a special photon-run. We report on the ...results of the low-mass e
+e
−-pair analysis. Since the most critical item is the poor signal-to-background ratio we also discuss the understanding of this background, in absolute terms, with the help of a detailed Monte Carlo simulation. We show preliminary results of the photon analysis and summarize the results of the hadron analysis preliminarily reported on already at QM'97 1.
In this paper we report on the application of a
robust approach based on a reweighted least squares method for the vertex reconstruction of the CERES/NA45 experiment at the CERN SPS for the case of ...160 GeV/u Pb+Au collisions and compare its performance with the presently used algorithm based on the minimization of summed Gaussian weights.
In the CERES/NA45 experiment a doublet of cylindrical silicon drift detectors (SDD) is used for vertex reconstruction and tracking. The vertex reconstruction algorithm has to cope with a background-contaminated environment. Furthermore, in the case of ultrarelativistic heavy-ion collisions where high event multiplicities occur (
dn
ch
dη
⋍ 500
), the probability of confusing hits from close or intersecting tracks is high. The algorithm needs to provide the precise vertex location even at high occupancies, at a reasonable speed. Our findings are that the robust iterative procedure presented here is about an order of magnitude faster than approaches using standard minimization packages, at a comparable or slightly better accuracy.
A study of elliptic flow and two-particle azimuthal correlations of charged particles (\(0.5 < p_{{\text{T}}} < 2.5\) GeV/c) and high-\(p_{\rm T}\) pions (\(1.2 < p_{{\text{T}}} < 3.5\) GeV/c) in Pb ...+ Au collisions at 158A GeV/c, close to midrapidity, is presented. Elliptic flow (v2) rises linearly with \(p_{\rm T}\) to a value of about 10\(\%\) at 2 GeV/c. Beyond \(p_{\rm T}\approx\) 1.5 GeV/c, the slope decreases and possibly indicates a v2 saturation at high \(p_{\rm T}\). Two-pion azimuthal anisotropies for \(p_{\rm T} > \) 1.2 GeV/c exceed the v2 values by about 60\(\%\) in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the near-side peak remains constant with centrality 0.23\(\pm\)0.03 rad, as expected for fragmentation, the away-side peak experiences broadening and disappears in central collisions.
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