A detailed study of pion production in central Mg - Mg collisions at a momentum of 4.3 GeV/c per incident nucleon was carried out using the GIBS set-up. It has been shown that the dependence of the average kinematical characteristics ( and ) of mesons on multiplicity differs from that for NN collisions at the same energy, which is due to nuclear effects. The temperatures of mesons have been estimated using two different selection criteria: in the rapidity interval and at angles in the CMS. A satisfactory fit for mesons can be achieved by using a form involving two temperatures and . The relative yield of the high-temperature component is . The results obtained by the intranuclear cascade model CASIMIR coincide with the experimental data estimated with both methods. From the analysis of angular distributions of mesons the anisotropy coefficient a was obtained. The anisotropy coefficient increases linearly with the kinetic energy (in the CMS). CASIMIR reproduces the increase of a with , but the slope is less steep than from experimental results.
The average kinematical characteristics of the PI- production.
The mean YRAP and its dispersion in various PT intervals.
Cross-sections are obtained for coherent interactions of π+ and K+-mesons with Al and Au nuclei at 250 GeV/c, leading to three, five and seven charged mesons. The total coherent cross-section is (4.3 ± 0.5)% of the inelastic cross-section for each of the four meson-nucleus interactions. In 85% of the coherent events, the charged meson production is accompanied by neutral mesons. Effective mass distributions are presented for coherently produced particles, including charged mesons and photons, carrying total measured energy of more than 85% of the initial energy. Charged particle and γ spectra are analysed. No charge asymmetry is observed within the coherently produced cluster.
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FRAGB - BEAM FRAGMENT WITH Z>=2.
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We study the production characteristics of 557 pairs of charmed hadrons produced in $\pi~{-}-Cu$\ interactions at 230GeV/c using a momentum estimator for charmed hadrons with missing decay products. We find, the mean value of the transverse momentum squared of the charmed pairs is $<$\pts$>=(1.98\pm 0.11\pm 0.09)\;$ GeV$~2$/c$~2$, the mean rapidity difference is $<|$\yd$|>=0.54\pm 0.02\pm 0.24$, and the mean effective mass is $<$\mef$>=(4.45\pm 0.03\pm 0.13)\;$ GeV/c$~2$. Comparing these results with the next-to-leading order QCD predictions we find an agreement for the \yd\ and \mef, whilst the measured mean value of \pts\ is significantly larger than the predicted value.
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C3H8 nucleus. P, DEUT and TRITIUM in the final state are considered as spectators.
P, DEUT and TRITIUM in the final state are considered as spectators.
C_3 H_8 nucleus. P in the final state are considered as spectators.
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ASYM is defined as follows: ASYM = (SIG(YRAP(P=3,RF=LAB)<1.1) - (SIG(YRAP(P=3,RF=LAB)>1.1)) / (SIG(YRAP(P=3,RF=LAB)<1.1)+ SIG(YRAP(P=3,RF=LAB)>1.1)).
ASYM is defined as follows: ASYM = (SIG(YRAP(P=3,RF=LAB)<1.1) - (SIG(YRAP( P=3,RF=LAB)>1.1)) / (SIG(YRAP(P=3,RF=LAB)<1.1)+SIG(YRAP(P=3,RF=LAB)>1.1)).
ASYM is defined as follows: ASYM = (SIG(YRAP(P=3,RF=LAB)<1.1) - (SIG(YRAP( P=3,RF=LAB)>1.1)) / (SIG(YRAP(P=3,RF=LAB)<1.1)+SIG(YRAP(P=3,RF=LAB)>1.1)).
Compensation of transverse momentum is studied in π+p interactions at 250 GeV/c. SignificantpT-transfer is found between c.m.s. hemispheres. With respect to the beam axis transverse momentum is compensated over the whole event, with respect to the sphericity axis mainly within one hemisphere. The highestpT in the event is mainly compensated by increased multiplicity. The QGSM and FRITIOF models qualitatively reproduce these effects, but important differences are observed.
Mean value of total transverse VECTOR defined as sum over all charged particles in the forward or backward hemispheres was measured.
Mean value of total transverse VECTOR defined as sum over all charged particles in the forward or backward hemispheres was measured.
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Negative pion spectra emitted in the reactions of 775 MeV/nucleon La139+12C and La139+139La reactions have been measured in coincidence with the projectile fragments using the HISS spectrometer at the Bevalac. Prominent peaks near the beam velocity were observed in the pion spectra. Position and widths of the peaks were studied as a function of the ‘‘sum charge’’ of projectile fragments which is a good measure of impact parameter; the smaller the ‘‘sum charge,’’ the smaller the impact parameter. The peak position down shifts with the smaller ‘‘sum charge.’’ The pion peak is wider in the transverse than in the longitudinal direction, possibly mirroring the velocity dispersions of projectile fragments in the early stage of reactions.
THE CHARGE IN THE TABLE IS THE SUM CHARGE OF OBSERVED FRAGB. A TWO-DIMENSIONAL SPECTRUM WAS FITTED BY A SINGLE TWO-DIMENSIONAL GAUSSIAN FUNCTION ON A FLAT BACKGROUND.
THE CHARGE IN THE TABLE IS THE SUM CHARGE OF OBSERVED FRAGB. A TWO-DIMENSIONAL SPECTRUM WAS FITTED BY A SINGLE TWO-DIMENSIONAL GAUSSIAN FUNCTION ON A FLAT BACKGROUND.
In this paper the main experimental results on some significant physical quantities obtained in He−Li collisions at 4.5A GeV/c are presented. The experiments have been performed at the Syncrophasotron from JINR Dubna, in the frame of the SKM 200 Collaboration.
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