A start-timing detector for the collider experiment PHENIX at RHIC-BNL Ikematsu, K.; Iwata, Y.; Kaimi, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/1998, Volume:
411, Issue:
2
Journal Article
Peer reviewed
Open access
We describe a start-timing detector for the PHENIX experiment at the relativistic heavy-ion collider RHIC. The role of the detector is to detect a nuclear collision, provide precise time information ...with an accuracy of 50 ps, and determine the collision point along the beam direction with a resolution of a few cm. Technical challenges are that the detector must be operational in a wide particle-multiplicity range in a high radiation environment and a strong magnetic field. We present the performance of the prototype and discuss the final design of the detector.
The invariant cross section as a function of transverse momentum for antideuterons produced in 158A GeV/c per nucleon Pb+Pb central collisions has been measured by the NA44 experiment at CERN. This ...measurement, together with a measurement of antiprotons, allows for the determination of the antideuteron coalescence parameter. The extracted coalescence radius is found to agree with the deuteron coalescence radius and radii determined from two particle correlations.
Two-particle correlations of negative pions as a function of charged particle multiplicity are studied in Pb+Pb collisions at \(\sqrt{s}=17.3\)GeV per nucleon using the NA44 experiment at the CERN ...Super Proton Synchrotron(SPS). We find that the source size parameters increase with the charged particle multiplicity. However the slope of the source size parameters plotted as a function of charged multiplicity is slightly larger at high multiplicity than at low multiplicity. The value of \(\lambda\) is independent of charged multiplicity. For Pb+Pb collisions, \(R_L\) is larger than \(R_{TS}\) and \(R_{TO}\) for all multiplicity intervals, whereas these three radius parameters were approximately equal in S+Nucleus collisions. The ratios (\(R_L/R_{TS}\)) and (\(R_L/R_{TO}\)) for Pb+Pb data show almost no dependence on charged multiplicity. The duration of pion emission \(\Delta \tau\) is constant at 3.8\(\pm\)1.1 fm/c as a function of the charged multiplicity in Pb+Pb collisions. Effective volume (V) is also calculated as V=\(\pi\times R_{TS}^2\times R_L\), assuming a cylindrically shaped source. We found, within the limited statistics, the effective volume rapidly increases at high multiplicity.
π−π−π− correlations from Pb+Pb collisions at 158 GeV/c per nucleon are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. The three-body effect is found to be stronger ...for Pb+Pb than for S+Pb. The two-dimensional three-particle correlation function is also measured and the longitudinal extension of the source is larger than the transverse extension.
Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta <p(T)> approximately 0.25 and 0.91 GeV/c. A three-dimensional analysis was applied to the lower ...p(T) data, while a two-dimensional analysis was used for the higher p(T) data. We find that the source-size parameters are consistent with the m(T) scaling curve observed in pion-correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity.
Proton and deuteron production has been observed in S+S and S+Pb collisions at 200 A\(\cdot\)GeV and in Pb+Pb reactions at 158 A\(\cdot\)GeV at the CERN SPS accelerator. For Pb+Pb triton production ...was also measured. The p and d spectra as well as the p and t spectra were observed in similar rapidity ranges and over similar ranges of transverse momenta per nucleon, making it possible to interpret the cross sections of the composite particles in terms of coalescence mechanisms. Volumes of homogeneity were extracted and compared to pion-pair HBT interferometry results. Special attention is given to the dependence on transverse mass, centrality and rapidity.
The NA44 Collaboration has measured yields and differential distributions of
K
+,
K
−,
π
+,
π
− in transverse kinetic energy and rapidity, around the center-of-mass rapidity in 158 A GeV/
c Pb+Pb ...collisions at the CERN SPS. A considerable enhancement of
K
+ production per
π is observed, as compared to
p+
p collisions at this energy. To illustrate the importance of secondary hadron rescattering as an enhancement mechanism, we compare strangeness production at the SPS and AGS with predictions of the transport model RQMD.
NA44 has measured the invariant cross section of deuterons and tritons at non zero
p
t
in 158 A·GeV lead on lead collisions at CERN SPS. Normalized transverse mass spectra and coalescence parameters ...versus
p
t
have been calculated showing a significant transverse flow. Radius parameters have been extracted using a simple thermal coalescence model. Results from RQMD+coalescence calculations are compared to the data.
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