1. |
- Aggarwal, M. M., et al.
(author)
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Event-by-event charged-neutral fluctuations in Pb plus Pb collisions at 158 A GeV
- 2011
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 701:3, s. 300-305
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Journal article (peer-reviewed)abstract
- Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
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2. |
- Aggarwal, M. M., et al.
(author)
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Photon and eta production in p plus Pb and p plus C collisions at root(NN)-N-S=17.4 GeV
- 2013
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In: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 898, s. 14-23
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Journal article (peer-reviewed)abstract
- Measurements of direct photon production in p + Pb and p + C collisions at root(NN)-N-s = 17.4 GeV are presented. Upper limits on the direct photon yield as a function of p(T) are derived and compared to the results for Pb + Pb collisions at root(NN)-N-s = 17.3 GeV. The production of the eta meson, which is an important input to the direct photon signal extraction, has been determined in the eta -> 2 gamma channel for p + C collisions at root(NN)-N-s = 17.4 GeV. (c) 2012 Elsevier B.V. All rights reserved.
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3. |
- Aggarwal, M. M., et al.
(author)
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Pion freeze-out time in Pb plus Pb collisions at 158 AGeV/c studied via pi(-)/pi(+) and K-/K+ ratios
- 2006
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 48:2, s. 343-352
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Journal article (peer-reviewed)abstract
- The effect of the final state Coulomb interaction on particles produced in Pb + Pb collisions at 158AGeV/c has been investigated in the WA98 experiment through the study of the pi(-)/pi(+) and K-/K+ ratios measured as a function of T-m- (m)0. While the ratio for kaons shows no significant T-m dependence, the pi(-)/pi(+) ratio is enhanced at small T-m - (m)0 values with an enhancement that increases with centrality. A silicon pad detector located near the target is used to estimate the contribution of hyperon decays to the pi(-)/pi(+) ratio. The comparison of results with predictions of the RQMD model in which the Coulomb interaction has been incorporated allows to place constraints on the time of the pion freeze-out.
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4. |
- Aggarwal, M. M., et al.
(author)
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Suppression of high-p(T) neutral pion production in central Pb+Pb collisions at root s(NN)=17.3 GeV relative to p+C and p+Pb collisions
- 2008
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In: Physical Review Letters. - 1079-7114. ; 100:24
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Journal article (peer-reviewed)abstract
- Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at root s(NN) = 17.4 GeV at midrapidity (2.3 less than or similar to eta(lab)less than or similar to 3.0) over the range 0.7 less than or similar to p(T)less than or similar to 3.5 GeV/c. The spectra are compared to pi(0) spectra measured in Pb+Pb collisions at root s(NN) = 17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N-part less than or similar to 300), the yield of pi(0)'s with p(T)greater than or similar to 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N-coll), while for central Pb+Pb collisions with N-part greater than or similar to 350, the pi(0) yield is suppressed.
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5. |
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6. |
- Aggarwal, MM, et al.
(author)
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Centrality and transverse momentum dependence of collective flow in 158 A GeV Pb+Pb collisions measured via inclusive photons
- 2005
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In: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 762:1-2, s. 129-146
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Journal article (peer-reviewed)abstract
- Directed and elliptic flow of inclusive photons near mid-rapidity in 158 A GeV Pb + Pb collisions has been studied. The data have been obtained with the photon spectrometer LEDA of the WA98 experiment at the CERN SPS. The flow strength has been measured for various centralities as a function of p(T) and rapidity over 0. 18 < p(T) < 1.5 GeV/c and 2.3 < y < 2.9. The angular anisotropy has been studied relative to an event plane obtained in the target fragmentation region that shows the elliptic flow to be in-plane. The elliptic flow has also been studied using two-particle correlations and shown to give similar results. A small directed flow component is observed. Both the directed and elliptic flow strengths increase with p(T). The photon flow results are used to estimate the corresponding neutral pion flow.
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7. |
- Aggarwal, MM, et al.
(author)
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Centrality dependence of charged-neutral particle fluctuations in 158A (GeVPb)-Pb-208+Pb-208 collisions
- 2003
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 67:4
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Journal article (peer-reviewed)abstract
- Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in 158A GeV/c Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes are analyzed by two different methods. Various types of mixed events are constructed to probe fluctuations arising from different sources. The measured results are compared to those from simulations and from mixed events. The comparison indicates the presence of nonstatistical fluctuations in both the charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charged-neutral fluctuations, a possible signature of formation of disoriented chiral condensates, are observed. An upper limit on the production of disoriented chiral condensates is set.
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8. |
- Aggarwal, MM, et al.
(author)
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Event-by-event fluctuations in particle multiplicities and transverse energy produced in 158A GeVPb plus Pb collisions
- 2002
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 65:5
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Journal article (peer-reviewed)abstract
- Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158A GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However, for photons the multiplicity fluctuations have been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.
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9. |
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10. |
- Aggarwal, M M, et al.
(author)
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Azimuthal anisotropy of photon and charged particle emission in Pb-208+Pb-208 collisions at 158 center dot A GeV/c
- 2005
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 41:3, s. 287-296
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Journal article (peer-reviewed)abstract
- The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in Pb-208 + Pb-208 collisions at 158 (.) A GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a Fourier analysis. For both the photon and charged particle distributions the first two Fourier coefficients are observed to decrease with increasing centrality. The observed anisotropies of the photon distributions compare well with the expectations from the charged particle measurements for all centralities.
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