C. Bormann

The kaon spectrometer at SIS

A double-focussing QD magnetic spectrometer has been developed and installed at the SIS heavy-ion facility at GSI in Darmstadt. The spectrometers primary purpose is to study meson production in energetic nucleus-nucleus collisions in detail. Its compact design is matched to the requirements of kaon detection with short flight path (5–6.5 m), large solid angle (up to 35 msr), wide momentum acceptance (pmaxpmin ⋍ 2), maximum momentum 1.6 GeV/c (1.9 GeV/c at reduced solid angle) and reasonable momentum resolution (⋍ 1% without and ⋍ 10−3 with ray tracing). A focal-plane length of about 1.5 m allows the efficient use of the detectors necessary for particle identification and ray-tracing, involving wire chambers, time-of-flight scintillators and Cherenkov detectors. Collisions can be characterized by two multiple-module plastic-scintillator hodoscopes detecting reaction fragments in the forward hemisphere. While the primary purpose for the construction of the spectrometer is the measurement of kaons, it can serve as a general purpose magnetic spectrometer. Its large solid angle also allows the study of two-particle correlations.

Properties of high-energy pions emitted from heavy-ion collisions at 1 GeV/nucleon

Positively charged pions and protons from collisions of Ne+NaF and Au+Au at 1 GeV/nucleon incident energy were measured near midrapidity. The center-of-mass pion spectra deviate from a Maxwell-Boltzmann distribution. The slope of the high-energy part of the pion spectra varies significantly with the system mass and little with the size of the reaction zone. While the total pion yield rises linearly with the number of participant nucleons, the highenergy component increases more than linearly.

Kaon production in heavy ion collisions and the nuclear equation of state

Abstract Double differential cross sections for protons, π + and K + are measured in Au + Au collisions at 1.0 GeV/u and Θ lab =44°±4° with a new magnetic spectrometer at SIS. The pion spectra show an enhancement at low momenta with respect to a thermal distribution and little dependence on the collision centrality. The high-energetic pions measured in semi-central collisions at approximately midrapidity exhibit an anisotropic azimuthal angular distribution, peaking at 90° and 270° with respect to the reaction plane. The same feature is observed for protons. The kaon to proton ratio increases with the number of participating nucleons, i.e. with the centrality of the collision, whereas the pion to proton ratio stays constant. The first data on subthreshold K + production in a heavy mass collision system are discussed with respect to nuclear matter properties by a comparison to microscopic transport calculations.

Transverse Energy Production in {sup 208}Pb+Pb Collisions at 158 GeV per Nucleon

Author(s): Margetis, S.; Alber, T.; Appelshauser, H.; Bachler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gasdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuhmichel, A.; Lsdiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.J.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puhlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, Hans G.; Rohrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schafer, E.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.

Subthreshold kaon production in Au on Au collisions at 1 GeV/u

Subthreshold kaon production in197Au+197Au collisions at 1.0 GeV/u has been investigated with the Kaon Spectrometer at SIS. At Θlab=44±4∘ we found aK+/p ratio of>3 · 10−4 for the momentum range 650 MeV/c to 1150 MeV/c.

Pion and kaon emission from the fireball formed in Ne + NaF collisions at 1–2 GeV/nucleon☆

Abstract Double differential cross sections for proton, π + and K + meson production have been measured in Ne + NaF collisions at 1 and 2 GeV/nucleon. Parameterizations of the meson spectra with Maxwell-Boltzmann distributions yield common inverse slope parameters for kaons and high-energy pions at each beam energy. No evidence for different freeze out temperatures can be deduced from the spectral slopes of the emitted particles.

Transverse energy production in Pb-208 + Pb collisions at 158-GeV per nucleon

Author(s): Margetis, S.; Alber, T.; Appelshauser, H.; Bachler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gasdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuhmichel, A.; Lsdiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.J.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puhlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, Hans G.; Rohrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schafer, E.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.

Preliminary results on Pb+Pb collisions from the Grid-TOF data analysed in Budapest

The first results from the NA49 experiment, using a large acceptance tracking detector with particle identification, are presented which have been obtained from the recent Pb-ion run at the CERN SPS. Preliminary spectra of kaons and protons identified by the Grid-TOF detector as well as Bose-Einstein correlations are shown.

Transverse Energy Production inPb208+ Pb Collisions at 158 GeV per Nucleon

Author(s): Margetis, S.; Alber, T.; Appelshauser, H.; Bachler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gasdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuhmichel, A.; Lsdiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.J.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puhlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, Hans G.; Rohrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schafer, E.; Schmitz, N.; Schonfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.

Meson Production in Heavy-Ion Collisions at 1 GEV/Nucleon

Relati vistic heavy-ion collisions provide a unique tool to study the properties of hot and dense nuclear matter. The high stopping power of nuclei in nuclear matter leads to a rapid heating and to a compression of the medium. Two classes of observables are available. One ofthem tests the dynamics of the nuclear matter expressed by pictorial words like flow, squeeze out and side splash, whereas the other class of observables explores the properties of hot and dense nuclear matter via particle production.