Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.     

Systematics of (p,p′) and (p, α) spectra from 14 MeV proton bombardment of medium-A targets

Differential cross sections have been measured between 30° and 150° for the (p, p′) and (p, α) reactions induced by 14 MeV protons in the following targets: ³⁵Mn, ³⁶Fe, ⁵⁸Ni, ⁵⁹Co, ⁶²Ni, ⁶³Cu and ⁶⁴Zn. The results have been compared with the spin-dependent statistical theory and good agreement was obtained for the (p, α) reactions with a level density parameter a = (0.138±0.008)A MeV^?1. This value is substantially lower than that obtained in a spin-independent analysis of the same data. The agreement of the (p, p′) spectra with theory is poor and it is found that a 15–40% contribution from precompound emission is required. The emission of low-energy protons from the (p, np) reaction was observed in all cases and comparison of the cross sections with these of the corresponding (p, n) reactions yields information on the competition between γ-ray and proton emission.     

Energy dependence of the angular distribution of Sc fragments produced in the interaction of 238U with 0.8–11.5 GeV protons

Angular distributions of various Sc nuclides formed in the interaction of ²³⁸U with 0.8, 3.0 and 11.5 GeV protons have been measured. The curves change from forward-peaked at 0.8 GeV to sideward-peaked at 11.5 GeV, the 3 GeV curve being closer in shape to that obtained at 0.8 GeV. The implications of this transition for the nature of the reaction mechanism are discussed.     

Investigation of the unusual behavior of projectile fragments using nuclear chemistry techniques

In recent years the question of the unusual behavior of projectile fragments formed in the interaction of relativistic heavy ions with copper nuclei was studied using nuclear chemistry techniques. As targets we used various copper disk arrangements. It is not the intention of this conference contribution to give a complete account of the entire procedure and its results. However, we want to present a few more recent experimental findings, some of them even in a preliminary form. We want to stimulate the discussion about the entire problem which might be part of the so-called anomalon phenomenon, as observed in the field of relativistic heavy ion interactions with a few other techniques such as nuclear emulsions or bubble chambers.     

φ meson production fromp\bar p collisions at\sqrt s = 1.8 TeV

Fermilab experiment E735 located at the CO intersection region of the $\sqrt s = 1.8$ TeV $p\bar p$ collider analysed over 900 Φ→K ⁺ K ^? events. Measured were the transverse momentum spectrum, the correlation between the average transverse momentum <pt> and the charged particle multiphcityN _c , as well as the probability of Φ production per charged track,N _Φ /N _c , versusN _c . We have also made an estinate of the total inclusive cross section for Φ mesons, $\sigma (p\bar p \to \phi X) = 7.3 \pm 2.2 mb$ .