Results on transverse mass spectra of neutral pions measured at central rapidity are presented for impact parameter selected 158·A GeV Pb + Pb, and Pb + Nb collisions. The distributions cover the range 0.5 GeV/c ≤ mT − m0 ≤ 4 GeV/c . The change of the spectral shape with centrality is studied in detail. In going from peripheral to medium central collisions there is a nuclear enhancement increasing with transverse mass similar to the well known Cronin effect, while for very central collisions this enhancement appears to be weaker than expected. PACS. 25.75.Dw Particle and resonance production 2 M.M. Aggarwal et al.: Transverse mass distributions of neutral pions from Pb-induced reactions at 158·A GeV

M. M. Aggarwal, A. Agnihotri, Z. Ahammed, A. L. S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T. C. Awes, P. V. K. S. Baba, S. K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K. B. Bhalla, V. S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, Z. K. Böröcz, D. Bucher, A. Buijs, H. Büsching, L. Carlen V. Chalyshev, S. Chattopadhyay, R. Cherbatchev, T. Chujo, A. Claussen, A. C. Das, M. P. Decowski, V. Djordjadz P. Donni, I. Doubovik, M. R. Dutta Majumdar, K. El Chenawi, S. Eliseev, K. Enosawa, P. Foka, S. Fokin, V. Frolov M. S. Ganti, S. Garpman, O. Gavrishchuk, F. J. M. Geurts, T. K. Ghosh, R. Glasow, S. K. Gupta, B. Guskov, H. A. Gustafsson, H. H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B. W. Kolb, I. Kosarev, I. Koutcheryaev, T. Krümpe A. Kugler, P. Kulinich, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y. Y. Lee, H. Löhner, L. Luquin, D. P. Mahapatra, V. Manko, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, G. C. Mishra, Y. Miyamoto, D. Morrison, D. S. Mukhopadhyay, V. Myalkovski, H. Naef, B. K. Nandi, S. K. Nayak, T. K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, P. Nilsson, S. Nishimura, P. Nomokonov, J. Nystran F. E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann,* V. Petracek,* W. Pinanaud, F. Plasil, M. L. Purschke, B. Raeven, J. Rak, R. Raniwala, S. Raniwala, V. S. Ramamurthy, N. K. Ra F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, C. Roy, J. M. Rubio, H. Sako, S. S. Sambyal, R. San S. Sato, H. Schlagheck, H.-R. Schmidt, G. Shabratova, I. Sibiriak, T. Siemiarczuk, D. Silvermyr, B. C. Sinha, N. Slav K. Söderström, N. Solomey, S. P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sum T. Svensson, M. D. Trivedi, A. Tsvetkov, C. Twenhöfel, L. Tykarski, J. Urbahn, N. v. Eijndhoven, G. J. v. Nieuwenhuize A. Vinogradov, Y. P. Viyogi, A. Vodopianov, S. Vörös, B. Wysłouch, K. Yagi, Y. Yokota, and G. R. Young

In this paper Au+Au collisions at 11.6A GeV/c are characterized by two global observables: the energy measured near zero degrees (E-ZCAL) and the total event multiplicity. Particle spectra are measured for different event classes that are defined in a two-dimensional grid of both global observables. For moderately central events (sigma/sigma(int) < 12%) the proton dN/dy distributions do not depend on E-ZCAL but only on the event multiplicity. In contrast the shape of the proton transverse spectra shows little dependence on the event multiplicity. The change in the proton dN/dy distributions suggests that different conditions are formed in the collision for different event classes. These event classes are studied for signals of new physics by measuring pion and kaon spectra and yields. In the event classes doubly selected on E-ZCAL and multiplicity there is no indication of any unusual pion or kaon yields, spectra, or K/pi ratio even in the events with extreme multiplicity. [S0556-2813(99)03704-8].

We have studied the timing and light yield characteristics of long and thin scintillator samples of various sizes. Both the light yield and the time resolution degrade exponentially with respect to the distance from one end; the inverse slope parameters for the time resolutions are found to be twice those of the light yield. This is interpreted in terms of a photoelectron statistics picture, which can also explain the observed position dependence of time resolution for time-of-flight counters.

Production of light particles (π±,K±,p) has been measured in both Si+A and p+A collisions. Several interesting features have been observed, among which are: the enhanced K+/π+ ratio and the larger 〈mt〉 for K+ and proton. Comparisons between ≊pp, pA and SiA collisions are discussed.