Search

The inclusive differential cross sections for the production of $$\pi^{\pm}$$ and $$k^{-}$$ mesons, protons, and antiprotons with momenta between 6 and 50 GeV/c and nuclear fragments of mass number $$1\leq A\leq 10$$ in the momentum range between 20 and 220 GeV/c were measured in carbon–lead collisions at a beam kinetic energy of 19.6 GeV per nucleon ( $$\sqrt{S_{NN}}=6.3$$ GeV). A comparison with the respective cross sections for carbon–carbon interactions is performed, and the dependence on the target mass number ( $$A$$ ) is estimated. The present analysis shows that the observed particles originate predominantly from peripheral interactions.

The invariant cross sections for forward charged-hadron production at zero angle in carbon–carbon collisions at a beam kinetic energy of 19.6 GeV per nucleon were measured at the U-70 accelerator in an experiment performed with the aid of a combined spectrometer including beam line 22 and detectors of the modified FODS setup. The beam line rigidity was varied between 7 and 70 GeV/ $$c$$ . The results are compared with the predictions of the FTFP model and a self-similar solution for nucleus–nucleus collisions.

The inclusive differential cross sections for forward production of nuclear fragments at an angle of 0 ∘ in CC collisions at beam energy 20.5 GeV/nucleon ( S N N = 6.3 GeV ) are presented. Measurements have been performed at the U-70 Accelerator Complex (Protvino) using a combined spectrometer on base of the beamline. Fragments selection was carried out by measuring of ionization in scintillation counters taking into account the data from threshold Cherenkov counters and hadron calorimeter. Fragment mass was determined through Cherenkov light emission angle measured in the spectrometer of ring imaging Cherenkov radiation. Data are given for fragments with charge 1 ≤ Z ≤ 6 , atomic number 1 ≤ A ≤ 10 and A / Z 3.4 with momenta from 20 to 210 GeV/c. The measurements are compared with Fritiof model, statistical models and theoretical parameterizations. The discovered differences between theory and experiment are discussed.

The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70GeV proton beam with carbon, silicon and lead targets were studied to detect decays of charmed \(D^{0}\), \(\bar{D}^{0}\), \(D^{+}\), \(D^{-}\) mesons and \(\Lambda_{c}^{+}\) baryon near their production threshold. Measurements of lifetimes and masses have shown a good agreement with PDG data. The inclusive cross-sections of charm production and their A-dependences have been obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measured cross-section of the total open charm production ( \(\sigma_{\rm tot}(c\bar{c}) = 7.1 \pm 2.3({\rm stat}) \pm 1.4({\rm syst})\) μb/nucleon) at the collision c.m. energy \(\surd s = 11.8\) GeV is well above the QCD model predictions. The contributions of different kinds of charmed particles to the total cross-section of the open charm production in proton-nucleus interactions vary with energy.

In the present experiment, the radiation from positrons moving in a periodically deformed crystal was observed for the first time. The spectra of radiation are measured in a wide range of energy. The experimental indication showing the existence of an undulator peak in radiation was obtained at a qualitative level and was confirmed by calculations. Crystal undulators provide an equivalent magnetic field of 1000 T and periods in the submillimeter range and consequently can be applied to the generation of X-rays and gamma-rays, of energies a hundreds times higher than the radiation in usual undulators.

Data from the SVD-2 experiment that were obtained at the IHEP accelerator in 70-GeV/c proton-nucleus interactions are analyzed with the aim of searches for an exotic Θ+ baryon that decays through the pK S 0 channel. The reaction pN → pK S 0 + X characterized by a bounded multiplicity of charged secondaries is used for this analysis. A resonance of mass M = 1526 ± 3(stat.) ± 3(syst.) MeV/c 2 and width Γ < 24 MeV/c 2 is observed in the invariant-mass spectrum of the pK S 0 system at a statistical significance of 5.6σ. The mass and the width of this resonance correspond to the recently found positive-strangeness Θ+ baryon, which was predicted to be an exotic baryon consisting of five quarks (pentaquark), $$uudd\bar s$$ . The total cross section for the production of a Θ+ baryon in pA interactions is estimated at a value within the range 30–120 μb for x F ≥ 0. An analysis of the A dependence of the cross section for Θ+-baryon production does not reveal a significant deviation from the A dependence for inelastic events (∼A 0.7).

Charmed-particle production in pp interactions at 70 GeV/c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being nch/4. The corresponding statistics are 4.96 event/µb. Part of the events were recorded in the magnetic spectrometer. Three three-prong decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer. All three are interpreted as D− decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as \(\bar D^0 \) decays. The total cross section for \(c\bar c\) production in the Feynman variable region −1

Measurements of 70 GeV proton dechanneling lengths in silicon crystals (110) and (111) are described. The agreement of the obtained results with the predictions of diffusion theory, Monte Carlo simulations and experimental data at other energies is shown.

The rechanneling and dynamic equilibrium effects are experimentally investigated in straight crystals at 70 GeV. Using the Lindhard reversibility rule, a qualitative analysis of the volume-capture possibilities in bent crystals is performed.

The existence of a volume capture of 70 GeV protons with a Si bent single cystal of (111) orientation into the channeling mode has experimentally been proved. Data on the probability of capturing protons into the channeling mode versus the bending radius of the crystal have been obtained together with information on the dynamics of volume captured particle dechanneling.

It is shown, that complete information about beam characteristics may be obtained with a bent single crystal. A 70 GeV proton beam emittance has been measured together with the beam halo at ⩾10 −7 from maximum, particle momentum spread with resolution of ΔP / P −4 .

Radiation emitted by positrons moving in a periodically deformed crystal has been experimentally observed for the first time. Radiation spectra have been measured in a wide energy range. Experimental evidence has been obtained for an undulator peak in a radiation spectrum, which is qualitatively consistent with calculations. Crystalline undulators ensure an equivalent magnetic field of 1000 T and a period in the submillimeter range and can therefore be used to generate x-ray and gamma radiation that is a hundred times harder than radiation in usual undulators.

The IHEP polarized proton beam with momentum up to 40 GeV/c from the decay of lambda hyperons is described. The measured characteristics of the beam are compared with the calculated ones. >

The idea of deflecting high-energy particles with the help of bent single crystals has been widely applied at the IHEP complex for beam forming. Results of work with the crystals used in the extracted beams are presented. >

Single-spin asymmetries for hadrons have been measured in collisions of transversely-polarized 40 GeV/c proton beam with an unpolarized liquid hydrogen target. The asymmetries were measured for pi+-, K+-, protons and antiprotons, produced in the central region (0.02 < Xf < 0.10 and 0.7 < Pt < 3.4 GeV/c). Asymmetries for pi+-, K+- and antiprotons show within measurement errors the linear dependence on Xt and change a sign near 0.37. For protons negative asymmetry, independent of Xt has been found. The results are compared with those of other experiments and SU(6) model predictions., 25 pages (Latex), 12 Postscript figures

The technique of beam focusing by a bent crystal is described and results from its application presented in this note. A 70 GeV 2 mm wide proton beam was deflected and focused into a narrow 200 μm wide strip.

The main parts of an apparatus for simultaneous measurements of the polarization and spin-rotation parameters in high-energy elastic scattering on polarized protons are described, including the beam design, the polarized target, detectors, fast electronics, and the data acquisition. Measurements have been performed in 1972 to 1974 at the Serpukhov accelerator with π − , K − and p of 40 GeV/ c , and with p, π + and K + of 45 Ge V / c incident momentum. In addition to the results for P and R , the experiment also yields information on the unpolarized differential cross section.

The principle of a method of separation of antideuterons is discussed in this article. The first results on pure antideuteron beam with momentum 12.2 GeV/c for the “Lyudmila” bubble chamber are presented. The intensity of 63 GeV primary proton beam is equal to 1012 per cycle, the mean quantity of \(\bar d \sim 0.7\) per frame with hadronic background ∼30%.