A radiation source based on the emission of electrons and positrons moving in a short bent crystal has been recently discovered. The emission of particles is due to oscillations of their trajectories near the point of reflections, where trajectories approach a tangent to bent atomic planes. In the experiment performed with the secondary electron beam of the U70 accelerator, it has been shown that the emission intensity can be increased by using a sequence of oriented bent crystals. Passing through six 2.5-mm-long silicon crystals, 7-GeV electrons lose on average 2.0 GeV on emission. This value is several times larger than that in an amorphous medium. Thus, an intense source of radiation has been demonstrated with prospects of application at accelerators.

At large accelerators, bent crystals are employed to deflect weakly divergent proton beams at the stages of extraction and collimation. We demonstrate that a divergent particle beam may be efficiently deflected using a crystal with a focusing edge. A proton beam with divergence near 1 mrad, which exceeds the Lindhard angle by a factor of 30, has been experimentally deflected by 1.8 mrad with efficiency near 15%. The proposed focusing crystal may serve as an element of a novel optical system for secondary-particle beams in the TeV energy region.

Bent crystals are used at large accelerators to deflect particle beams for extraction and collimation. Not only the deflection but also the focusing of beams by bent crystals can be required for recently formulated proposals for investigations at the Large Hadron Collider (LHC) with a fixed target. The experimental results on the focusing of a 50-GeV proton beam with a new crystal device, which can be used in a circulating beam of a large accelerator such as the LHC, have been reported.

A station for splitting a 50-GeV proton beam using a bent crystal is described. Intelligent design of the bending device is a specific feature of this station, which minimizes loss of particles in beam splitting. The commissioning of the new station has made it possible for two experimental setups to operate at a time.

The emission of photons in the motion of a 10-GeV positron beam in bent silicon crystals has been experimentally investigated. The experimental data are compared with the theoretical calculations.

The results of studying the \(\Lambda \bar \Lambda \) system produced in the reaction π−p→ \(\Lambda \bar \Lambda \)n at a π−-meson energy of 40 GeV are reported. Experimental data (∼2300 events) were obtained on the ITEP 6-meter spectrometer with a beam of the IHEP U-70 accelerator. The invariant-mass spectra for the events dominated by the singlet or triplet \(\Lambda \bar \Lambda \) states were found to differ considerably from each other. The data give evidence for the existence of resonance \(\Lambda \bar \Lambda \) states of the system in the mass regions near 2.3, 2.5, and 2.8 GeV.

The results of studying the ΛΛ̅ system produced in the reaction π − p → ΛΛ̅ n at a π − -meson energy of 40 GeV are reported. Experimental data (∼2300 events) were obtained on the ITEP 6-meter spectrometer with a beam of the IHEP U-70 accelerator. The invariant-mass spectra for the events dominated by the singlet or triplet ΛΛ̅ states were found to differ considerably from each other. The data give evidence for the existence of resonance ΛΛ̅ states of the system in the mass regions near 2.3, 2.5, and 2.8 GeV.

The orientation dependences of the energy release in showers formed in transparent garnet crystals with thicknesses of 23 and 50 mm are measured, and the influence of the orientation of the crystals on the absorption of a shower in an amorphous radiator is determined.

The IHEP accelerator at Serpukhov has been used in a new experiment involving complete absorption of a proton beam in a search for prompt neutrinos in order to determine the cross section for production of charged particles in the interaction of 70-GeV protons with iron nuclei. The detector was the neutrino facility of the IHEP-JINR collaboration with useful weight of about 50 tons. No prompt-neutrino signals were found among the detected neutrino interactions identified as electron-neutrino interactions. This has made it possible to obtain a stronger bound on the cross section for production of charmed particles-the upper limit is 2.4-mu-b/nucleon (90% C.L.). This result is consistent with the predictions of quantum chromodynamics.

A search has been made for weakly interacting light neutral particles in a beam-dump experiment at the 70-GeV accelerator of the Institute of High Energy Physics, Serpukhov. Analysis of high-energy electromagnetic showers from the possible decays H --> e+e- and H --> gammagamma in the neutrino detector of the IHEP and the Joint Institute for Nuclear Research reveals no signal above the background. Limits are found on the mass of the light Higgs boson within the framework of the standard model on the basis of theoretical branching ratios for the production of light Higgs bosons in the decays pi+/- --> e+/- --> nu(e) H, K+/- --> pi+/- H, K(L)0 --> pi0H, and eta' --> etaH.

A new experiment at the Serpukhov accelerator on total absorption of a proton beam is used to search for direct neutrino production in interactions of 70-GeV protons with iron nuclei. A SKAT bubble chamber filled with freon bromide was used for the detector. An upper bound on the cross section for production of charmed particles is obtained.

The results of the first experiments on the interaction of 2--30-GeV neutrinos with emulsion nuclei at the IHEP (Serpukhov) accelerator are presented. Nine of the thirteen detected events are interpreted as CC neutrino interactions. The average numbers of shower, grey, and black tracks in these events were 2.2 (without muons), 2.1, and 3.6, respectively. The average excitation energy of the nucleus was 214 +- 29 MeV.

Preliminary results are presented on the determination of the energy dependence of the cross section for quasielastic scattering of muon neutrinos by neutrons, ..nu../sub ..mu../+n..--> mu../sup -/+p, in the region 3< or =E< or =30 GeV. From a combined analysis of the total and differential cross sections we have determined the parameter M/sub A/ = 1.00 +- 0.07 GeV/c/sup 2/. In the overlapping energy region the data are in good agreement with the results of other experiments.

The cross section and differential distribution dN/dq/sup 2/ of the reaction ..nu../sub ..mu../n..--> mu../sup -/p have been measured at muon-neutrino energies of 2--20 GeV. A value of the parameter M/sub A/ = 0.90 +- 0.08 has been determined from the dependence of the quasielastic-reaction cross section on the neutrino energy and a value M/sub A/ = 0.86 +- 0.18 has been determined from the analysis of the distribution dN/dq/sup 2/.