A. Kuznetsov

The WASA Detector Facility at CELSIUS

The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique fea ...

Detector setup for a storage ring with an internal target

Abstract A detector setup for the cooler storage ring CELSIUS is described. The setup detects particles produced in interactions between the internal beam and a cluster-jet target. Particles emitted in the forward direction are measured by means of arrays of plastic scintillators and proportional counters. Particles, particularly photons, emitted more isotropically are measured by means of two calorimeters containing CsI(Na) crystals. The performance of the setup is given for neutral meson production in proton-proton and proton-deuteron interactions in the energy range 290–1360 MeV.

Fragmentation of 9 GeV/c deuterons in the region of proton transverse-momenta of 0.5-1 GeV/c and the deuteron wave-function at small distances

Abstract Momentum spectra of protons emitted at angles of 0.103, 0.139 and 0.157 rad in fragmentation of 9 GeV/ c deuterons on 1 H, 2 H and 12 C nuclei have been measured at the JINR synchrophasotron by using a magnetic spectrometer. It is found that the shape of the high-momentum parts of the spectra is defined only by the deuteron structure and the mechanism of deuteron-nucleon interaction and does not depend on a target. The contributions to the differential cross section of the 1 H(d, p)X reaction have been determined, which are conditioned by elastic and inelastic scatterings of deuteron nucleons on a proton, stripping, their interference, and also the excitation of the pion degrees of freedom. In the framework of the light front dynamics, calculations of the proton spectra with the deuteron structure functions for the Paris, Reid soft core, and Bonn potentials have been performed; a better agreement with the experiment is achieved with the deuteron wave function for the Paris potential. A conclusion is made that the nucleons in a deuteron keep their individuality up to relative motion momenta of ∼ 1 GeV/ c .

The structure of the high-momentum parts of the deuteron spectra from d-d collisions at 4.3, 6.3 and 8.9 GeV/c

Abstract The experimental data on d-d collisions at 4.3, 6.3 and 8.9 GeV/ c , exhibiting the two-peak structure in the high-momentum parts of the secondary deuteron spectra at momentum transfers | t | ≈ 0.4–0.8 (GeV/ c ) 2 , are presented. An analysis of the results in terms of the multiple nucleon-nucleon scattering model is given. Some conclusions about the mechanism of the elastic and quasielastic d-d scattering at the above-mentioned momentum transfers are made.

Proton spectra from 6.3 GeV/c deuteron break-up on 1H, 2H, C, A1 and Bi nuclei

Abstract The proton spectra resulting from 6.3 GeV/ c deuteron break-up on 1 H, 2 H, C, Al and Bi nuclei were measured at an angle of 103 mr (lab) in the momentum interval from 2.6 to 3.6 GeV/ c . The measurements were made at the JINR synchrophasotron with a one-arm magnetic spectrometer on-line with a computer. The results, apart from the effects of pion production, are reasonably reproduced in the framework of the Glauber multiple scattering model, taking into account the relativistic deformation of the deuteron wave function.

CELSIUS as an η factory

Abstract The WASA project at the CELSIUS storage ring is being prepared for high-luminosity experiments to study rare decays of light mesons, in particular the η meson. The CELSIUS ring together with the newly developed pellet target will serve as an efficient η factory.

Fragmentation of 6.3 GeV/c deuterons on h,d,c,al, and bi nuclei

The momentum spectrum of protons emitted in the reaction d + A ..-->.. p + X at 6.3 GeV/c with hydrogen, deuterium, carbon, aluminum, and bismuth is presented. The measured spectra are shown, and the differential cross section calculated. 5 references. (JFP)

Elastic and quasielastic d‐d scattering at 4.3, 6.3 and 8.9 GeV/c

A two-peaked structure from previous work is studied in the deuteron momentum spectrum in the process d + d ..-->.. d + X at 4.3 to 8.9 GeV/c. It is concluded that the elastic deuteron scattering at momentum transfers approx. 0.3 to 1.0 (GeV/c)/sup 2/ occurs in the main through such double scatterings when in simultaneous collisions both the nucleons of the incident deuteron scatter each on one of the two target nucleons. Such a mechanism permits rather a great momentum to both the deuteron nucleon to be transferred without disturbing their relative intranuclear motion. 7 references. (JFP)

Effects of the nuclear binding of nucleons on pion spectra

Abstract Using a magnetic spectrometer a comparative study was made of the energy spectra of π+ and π− -mesons produced in free pp-collisions as well as in pp- and pn-collisions in deutrons and in carbon nuclei at 654 MeV. The forms of the spectra of pions from deuterium and carbon are found to differ due to: a) a larger extent of correlation of nucleons in carbon nuclei than in deuterons; b) differences in the momentum distributions of nucleons in these nuclei; c) secondary pion-nucleon interactions in carbon nuclei. At ≈ 90° in the centre-of-mass system of two colliding nucleons the ratio of the differential cross sections for the production of π+-mesons on free protons and on protons in deuterons and in carbon nuclei was found to be equal to d σ d ω [ p + p →π + ] H : d σ d ω [ p + p →π + ] D : d σ d ω [ p + p →π + ] C = 1:0.79:0.40 , whereas the yields of π− -mesons per neutron for deuterium and carbon were found to be equal. The measured ratio (dσ+/dω)/(dσ−/dω) of the differential cross sections for the production of positive and negative pions on deuterium and carbon is equal to 10.3±1.3 and 6.0±0.8, respectively. The decrease of the value of this ratio for carbon is caused by a considerable contribution of the secondary exchange interaction π0+ n → π−+p to the yield of π− -mesons.