Search

A narrow centrally produced neutral 3π system is seen at about 1080 MeV/c2 in the reaction pp → ppπ+π−π0 at 19 GeV/c. There is no evidence of ρπ in the final state of this system. The possibility that this system is created in gluon gluon scattering is discussed.

Two narrow peaks at about 1500 and 1800 MeV/c2 are seen in the distributions of invariant mass of the assumed six-pion systems in the final states of Ne and He reactions at 607 MeV/c. In He-reactions the peaks are seen only in the forward direction, while in Ne-reactions they are also seen in the backward direction with momenta near the momentum of the incident antiproton. The peaks could possibly be due to glueballs.

A sharp peak at 1150 MeV c−2 in the π−π+π−π+ -system in the final state of 4He-reactions at 0.6 GeV c−1 incident momentum is seen. This system probably has spin-parity = 0+ or 2+, which are possible spin-parity assignments of a glueball.

The ratio between the numbers of negative and positive leading pions in 20Ne reactions at 607 MeV/c can only be explained in terms of parton fragmentation.

The reaction p + p → pπ+π–πo + p at 19 GeV/c incident momentum is discussed in terms of gluon bremsstrahlung. The produced gluon polarization is in agreement with previous results on two-pion systems and with theory. The oblateness effect of the gluon polarization on the three pion jet is on the other hand much larger than obtained by perturbative, lowest order calculations.

The measured cross sections for K0s and Λ0 (Σ0) production in A reactions at 607 MeV/c incident momentum and the number of quark recombinations give the cross section σ(s) for strange particle production for target nuclei with A = 2, 4, 20 nucleons, respectively. The result favours the relation σ(s) ∝ A1/3. Scattering of an antiquark off a virtual s-pair, or gluon Bremsstrahlung emitted by scattering of an incident antiquark passing through nuclear matter, are possible processes consistent with this relation. Models inconsistent with this relation may be wrong.

Leading mesons are seen in 4He → neutral strange particles at 0.6 GeVc−1 incident momentum. These results differ somewhat from our previous results from Ne-reactions. The concept of an "effective target" is useless.

Experiments indicate that gluons emitted in p-p collisions at s = 40 (GeV)2 and detected by their π+-π− decay are linearly polarized.

Ag/Br reactions at 1.4 GeV/c incident momentum are studied by means of the emulsion technique. A group of short range charged particles is observed. For the events with one short track, a backward and transversal emission is seen, which probably is due to some very fast process. For the events with two short tracks, a back-to-back emission is seen, indicating some two-body decay, where the target nucleus possibly behaves spectator-like.

We present some experimental results for the production of pion-pairs in proton-proton collisions at 19 GeV/c by analogy to electromagnetic Bremsstrahlung. The observed features are consistent with the concept of gluon Bremsstrahlung.

Some features of Ag/Br reactions at 1.4 GeV/c incident momentum are studied by means of the emulsion technique. The distributions of the number of charged particles/event are present. The angular distributions indicate some anisotropic process in the nuclear matter, possibly shock-waves, and some back-to-back emission.

Data on the reactions pn → NπΔ(1236) and pp → NπΔ(1236) at 19 GeV/c have been used to study the reactions pN → N(πΔ) and pN → (Nπ)Δ in terms of crossed channel isospin amplitudes. The cross section of the reaction pN → N(πΔ) is about twice that of pN → (Nπ)Δ. Each reaction can be described by three amplitudes MIIx, where Ix and I are the isospins of the exchange and of the Δπ or Nπ system, respectively. We find that for the reaction where the pion clusters to the Δ, i.e., pN → N(πΔ), the isoscalar exchange is the leading mechanism, but the M3/21 amplitude also gives a large contribution. For the other reaction, i.e., pN → (Nπ)Δ, the isovector exchange amplitude leading to a I = 3/2 Nπ state, is dominating. The Ix = 2 exchange amplitude is unimportant. These results have been compared with the results of similar analyses of other three-body reactions and some common features and differences have been pointed out. Available data at other energies have been used to investigate the energy dependence of the isospin amplitudes for the reaction pN → ΔπN in a double exchange representation. It is found that the amplitude involving isoscalar exchange is dominating above 20 GeV/c and has a weak energy dependence while the amplitude with double isovector exchange has an energy dependence pnlab with n ≈ - 1.5.

Interdiffusion at room temperature in evaporated Au-Sn films was studied by in situ backscattering of 2.0 MeV 4He ions and X-ray diffraction. The interdiffusion resulted in the formation and growth of an AuSn phase region which subsequently transformed into AuSn2 and AuSn4.

We study the angular distributions of the non-relativistic fast charged particles in Ag/Br reactions at 1.4 GeV/c incident momentum in photographic emulsions. For some events with three such particles, two of them are emitted in almost opposite directions, or "back-to-back". Some of these particles have been identified as protons. Possibly has a multinucleon cluster or "hot-spot" in the target nucleus decayed.

Some simple arguments are presented why the trajectory behaviour may be expected if hadrons consist of some constituents like quarks, bound by some range-independent force which may be measured by means of the slope of the trajectories.