A study of angular correlations of projectile and target fragments in 1.4 A GeV Kr+Ag(Br) collisions

A sample of high multiplicity quasi-central Kr⁸⁴+Ag(Br) interactions has been'analysed in terms of angular correlations between projectile and target fragments. The azimuthal correlation of PFs and TFs suggests the presence of a weak collective (bounce-off) effect. Other observations like, target recoil velocity,F/B ratio of TFs with respect to direction of their source etc. are interpreted in terms of a simple two body quasi-elastic scattering and a modified Maxwell-Boltzmann distribution.     

Study of projectile fragmentation in the reaction (158 A GeV) Pb + Pb using CR-39

The fragmentation of Pb ions at 158 A GeV energy produced in the interaction with Pb target has been studied using a CR-39 track detector. A stack comprising of 64 detectors was prepared such that a target of 1 cm thickness was sandwiched between the sheets of CR-39. The purpose of this exposure geometry was to calibrate CR-39 with respect to relativistic heavy ions as well as to study the fragmentation of Pb ions at 158 A GeV energy. The exposure was carried out at the SPS beam facility of CERN at normal incidence with a fluence of . Two detectors from the exposed stack have been selected for this study: one before and the other after the target material. After etching, the detectors were scanned using an optical microscope and the etched track lengths and the diameters of the track openings were measured manually. Considering that the lengths of tracks provide the best charge resolution for Z>65, we have measured track lengths for a sufficiently large number of fragments to identify individual charge states for 65<Z<83. The total charge-changing cross section has also been determined.     

A partial wave analysis of the (Kππ) system in the reaction π− p→(K +π−π0)Λ at 3.95 GeV/c

Results from a partial wave analysis of theKππ system produced in the hypercharge exchange reaction π^? p→(K ⁺π^?π⁰)Λ at 3.95 GeV/c are presented. SignificantQ ₁ production is observed but no evidence is found forQ ₂ production thus confirming the results obtained in a previous decay Dalitz plot analysis of the same reaction. The relative phase behaviour of the 1⁺(K?) partial waves obtained with the present analysis provides additional confirmation of the resonance interpretation of theQ ₁ enhancement. Information is also obtained about its production properties and the role played by the Λ polarization in the hypercharge exchange reaction. This is compared with the results obtained in the reactionK ^? p→(π⁺π^?π⁰)Λ at 4 GeV/c.     

Pecularities in produced-particle emission in <Superscript>208</Superscript>Pb+ Ag(Br) interactions at 158 <Emphasis Type="Italic">A</Emphasis> GeV/<Emphasis Type="Italic">c</Emphasis>

The angular structures of particles produced in ²⁰⁸Pb-induced collisions with Ag(Br) nuclei in an emulsion detector at 158 A GeV/c have been investigated. Nonstatistical ringlike substructures in the azimuthal plane of the collision have been found and their parameters have been determined. An indication of the formation of ringlike substructures from two symmetrical emission cones, one in the forward and the other in the backward direction in the center-of-mass system, has been obtained. The ringlike substructures’ parameters have been determined. The experimental results are in an agreement with I.M. Dremin’s idea that the mechanism of the ringlike substructures’ formation in nuclear collisions is similar to that of Cherenkov electromagnetic radiation. The text was submitted by the authors in English.     

A partial-wave analysis of the neutral 3π system produced in the reaction π−p → (π+π−π0) n at 12 and 15 GeV/c

Data on the charge-exchange reaction π^?p → (π⁺π^?π⁰)n have been taken at beam momenta of 12 and 15 GeV/c, using the CERN Omega Multiparticle Spectrometer. A partial-wave analysis has been made of the (3π)⁰ system. We observe both natural and unnatural spin-parity production. The natural parity states can be identified with established resonances. In addition a natural spin-parity enhancement is observed at a mass of about 2 GeV/c² with J^P = 4⁺ preferred. We have called this effect the A₂¹ (2030). The unnatural spin-parity production found is consistent with reggeized Deck model predictions. No unambiguous A₁ or A₃ production is observed.     

Production of A20and ω1 (1675) in the reaction π−p → π+π−π0n at 12 and 15 GeV/c

Data on the reaction π^?p → π⁺π^?π⁰ have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of $\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A₂⁰ production is studied, and a comparison of $\text{ω(780),}\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ production is made.