Neutron-proton elastic scattering from 10 to 70 GeV/c

The neutron-proton elastic differential cross section has been measured for incident momenta between 10 and 70 GeV/c and for values of the momentum transfer squared between 0.1 and 2.8 (GeV/c)². The forward peak and the break at about ∣t∣ = 1 (GeV/c)² are very similar to corresponding pp data.     

Proton-proton scattering above 3 GeV/c

A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A_NN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3GeV/c to 50GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the $ \rho$ \rho , $ \omega$ \omega , f₂, and a₂ trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.     

Coherent production of particles by 67 GeV/c protons on emulsion nuclei

Coherent reactions were observed among one-, three- and may be five-prong interactions of 37 GeV/c protons in nuclear emulsion. Their cross sections were estimated and compared with other data on coherent production in emulsion.     

Neutron-proton charge-exchange scattering from 8 to 29 GeV/c

The differential cross sections for neutron-proton charge-exchange scattering have been measured for incident neutron momenta between 8 and 29 GeV/c and for four-momentum transfers |t| between 0.002 and 1.0 (GeV/c)². A neutron beam with a broad momentum spectrum was scattered from a liquid hydrogen target. The momenta and scattering angles of the forward-scattered protons were measured by a spark-chamber magnet spectrometer. The flight times and scattering angles of the recoil neutrons were measured by a bank of thick scintillation counters. The efficiencies of the neutron counters were determined in a separate measurement. Absolute normalization of the data was obtained from a measurement of the diffraction dissociation of neutrons from carbon nuclei. Differential cross sections, based on ～ 23 000 events, are presented for 9 different momenta. The shape of the differential cross sections and the momentum dependence are examined in detail.     

ExperimentalJ/ψ hadronic production from 150 to 280 GeV/c

A detailed study ofJ/ψ hadronic production has been performed in a high statistics experiment (more than 1.5 10⁶ J/ψ observed in their dimuon decay mode). Data have been taken with incident π^±,K ^±,p ^±, on hydrogen and platinum targets, at 150, 200 and 280 GeV/c. We find from the observed nuclear dependance of the cross sections, that about 18% of theJ/ψ are produced diffractively. Using known structure functions of the quarks in the nucleon and in the pion, we derive estimations for the gluon structure functions.     

Coherent dissociation of oxygen into four alphas in photoemulsion at 4.5 A GeV/c

The search for and study of the coherent dissociation reaction ¹⁶O → 4 have been made at 4.5 GeV/c per nucleon in emulsion. The momentum and correlation characteristics of alphas cannot be described by the statistical model of prompt fragmentation. The decay “temperature” is considerably smaller than one for the usual multifragmentation of relativistic projectiles.     

Hadron Pt spectra from 0.03 to 6 GeV/c from PHOBOS

We review some of the latest results on identified and non-identified particle spectra for d+Au and Au+Au collisions at √s _NN =200 GeV from the PHOBOS Experiment at RHIC. No enhancement of hadron yields at very low PT is observed. Analysis of the high-PT spectra in d+Au and Au+Au collisions reveal the strong final state effects for central Au+Au collisions. The first measurements of identified particle spectra and particle ratios from the PHOBOS Time of Flight (ToF) detector are presented for d+Au collisions. Detailed results on centrality and pseudorapidity dependence of transverse momentum spectra, which may have important physics implications. are also shown.     

αα elastic scattering at 4.32 GeV/c and 5.07 GeV/c

αα elastic scattering was measured at 4.32 GeV/c and 5.07 GeV/c incident momenta. The four-momentum transfer range, extending from ?0.05 to ?0.77 (GeV/c)², covers the first and second minimum regions. The results are compared with calculations based on Glauber theory.     

Jet production from nuclei at 400 GeV/c

Results are presented from a calorimeter study on the production of jets in large-E_T proton-nucleus collisions at 400 GeV/c. Jet-like large-p_T events from eight nuclear targets are seen with a special jet trigger. As previously observed, the cross section for such events increases slightly faster than the atomic number, much like in the production of large-p_T single hadrons. Data on energy flows and multiplicities suggest that a heavy nucleus does not significantly widen the angular distribution of the beam remmants. In the central region the particle flow in hard nuclear collisions is similar to that in soft nuclear collisions.     

Λ and K s 0 production in pC collisions at 10 GeV/c

The experimental data from the 2-m propane bubble chamber have been analyzed for pC → Λ(K _s ⁰ )X reactions at 10 GeV/c. The estimation of experimental inclusive cross sections for Λ and K _s ⁰ production in the p ¹²C collision is equal to σ_Λ = (13.3 ± 1.7) mb and σ _{K s} ⁰ = (4.6 ± 0.6) mb, respectively. The measured 〈Λ〉/〈π⁺〉 ratio from pC reaction is equal to (5.3 ± 0.8) × 10⁻², and it is approximately two times larger than the 〈Λ〉/〈π⁺〉 ratio simulated by the FRITIOF model and than that of experimental pp reactions at the same energy. The text was submitted by the authors in English.     

Polarization in proton-proton elastic scattering at 10, 14 and 17.5 GeV/c

Data on the polarization parameter in pp elastic scattering in the |t|-range from ∼0.1 to ∼ 2.9 (GeV/c)² and at 10, 14 and 17.5 GeV/c are presented.     

Analyzing power in the reaction pp→dπ for beam momenta from 1.17 to 1.96 GeV/c

The analyzing power A_y0 in the reaction p↑p→dπ⁺ has been measured using the polarized proton beam at Argonne National Laboratory's zero gradient synchrotron. Data were taken at beam momenta of 1.17, 1.47, 1.70, and 1.96 GeV/c and for pion center of mass angles from 8° to 163°.     

Polarization in K+n charge exchange scattering between 0.851 GeV/c and 1.351 GeV/c

The polarization parameter for K⁺n charge exchange scattering has been measured at five momenta between 0.851 GeV/c and 1.351 GeV/c for centre of mass angles $\text{?0.8 <}\text{cos}\text{θ}{}^1\text{< 0.8}$. Results from a phase shift analysis incorporating these results are presented. No Z¹ resonances are observed.     

Collective sea-gull effect in πp interactions at 250 GeV/c

A collective “sea-gull” effect is observed for a system of fast hadrons produced in the fragmentation regions of nondiffractive π⁺p-interactions at 250 GeV/c. The effect is not reproduced by the FRITIOF fragmentation model in its details. It is demonstrated that hard-like processes, both in the collision phase and in the fragmentation phase, are not properly treated in the model.     

A model for the multiplicity distribution in pp-collisions from 5 to 300 GeV/c

The multiplicity distribution of charged particles in pp-collisions in the range 5–300 GeV/c is explained on the basis of a dynamical model which leads to a specific mixture of Poisson distributions.     

Recent study for multibaryon states with strangeness in pC interaction at 10 GeV/c

Strange multibaryon states with Λ-hyperon and K _s ⁰ -meson subsystems has been studied from 700 000 stereo photographs or 10⁶ inelastic interactions which was obtained from expose of 2-m propane bubble chamber (PBC) LHEP, JINR to proton beams at 10 GeV/c. The obtained results from PBC can be divided into three subjects: in-medium effects of hadronic particles; baryon spectroscopy; hyper-nucleus production. At present the experimental situation is confused; so is theory. New accelerator research complexes has unique possibility for high-statistic and 4π-geometry study of exotic states.     

Properties of the inclusive pion spectrum from pp collisions: 28.5 GeV/c to about 10 GeV/c

The spectra of pions are studied in the inclusive reactions p + p → π^± + anything in bubble chamber data at 28.5 GeV/c. Comparisons are made with ISR π⁺ spectra to examine energy dependence.     

Search for the ρρ enhancement near 1700 MeV/c in the reaction at 8.3 GeV/c

Results are presented from a search for a ρ⁰ρ⁰ enhancement in antiproton annihilations. A ρ⁰ρ⁰ resonance was recently observed in radiative ψ decays, and its existence has been supported by the results of an antiproton experiment at 5.7 GeV/c. No indication of this ρ⁰ρ⁰ enhancement is seen is our data, in direct contradiction with the earlier, lower statistics experiment.