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Experimental study on muon catalyzed dt fusion in a triple mixture of hydrogen isotopes (H/D/T) was carried out at the JINR phasotron. The measurements have been performed at various temperatures and densities with liquid and gaseous H/D/T mixtures. Results are presented for the main characteristics of the dtμ cycle. A reduction of the number of dt fusions is observed when hydrogen is added to the D/T mixture, This is mainly due to muon loss to the pt and pd cycles, which have a high sticking probability. We also observe an increase of the cycle rate when the temperature of the H/D/T mixture rises. This confirms the theoretical prediction.

Muon catalyzed dt fusion in dense D/T and H/D/T gas mixtures of hydrogen isotopes is studied by the MCF collaboration at JINR. The measurements were carried out with a high pressure target at the JINR phasotron in the temperature range 300-800 K at mixture densities \( \simeq 0.4{\text{ and }} \simeq {\text{0}}{\text{.8 LHD}}\). Tentative experimental results obtained by several analysis methods are presented.

Preliminary data are first presented for the measurements of effective parameters of MCF processes in dense D/T mixtures obtained by a novel method. Results are compared with the ones obtained by the “standard” method.

The ddµ molecule formation rate is experimentally measured for the two hyperfine states of the dµ-atom in the temperature range of 5–30 K. Results are consistent with a preliminary measurement by the TRIUMF group and contradict theoretical predictions. The work has been performed on the JINR phasotron (Dubna).

The original experimental method for further µCF study in double, D/T, and triple, H/D/T, mixtures of high density is considered. This method is the base of the international project sponsored by the ISTC.

An installation is made to investigate the temperature and spin dependence of the ddu “meso”-molecular formation rate in deuterium in solid, liquid and gaseous phases. It is composed of a target cooled with helium of a volume equal to 280 cm3 and target thermostabilization and gas-handling systems. The temperature of the target in the range 5-40 K can be fixed with an accuracy of 0.2 K.

The ddµ molecule formation rate is experimentally measured for the two hyperfine states of the dµ-atom in the temperature range of 5–30 K. Results are consistent with a preliminary measurement by the TRIUMF group and contradict theoretical predictions. The work has been performed on the JINR phasotron (Dubna).

Inclusive production ofK 0 andK * (892)0 mesons inK + A-interactions (A=Be, Cu, Pb) at the energy 11.2 GeV has been investigated to study hadronisation of the leading $$\bar s$$ -quark; the results are presented. Double differential cross sections d2σ/dx f dp 2 were measured in the region of incident particle fragmentation (0.4≦x f ≦1,p t ≦0.5 GeV/c). The experimental data obtained were analysed on the basis of the Lund model FRITIOF and a quark-gluon model that takes into account colour screening and hadron formation length effects. The experimental data confirm the picture of hadronisation of the leading $$\bar s$$ -quark developed in the latter model.

The q2 dependence of the vector form factor has been investigated using 3.2 × 104 K+ → π0e+ν decays. The usual linear parametrization. ƒ + (q 2 ) = ƒ(0)(1+λ + q 2 /m π 0 0 ) gives λ+ = 0.0284±0.0027. An analysis of the Dalitz plot density distribution for Ke3+ decays yields the values for the scalar and tensor couplings ƒs and ƒt, and their relative phase angle ost.

The concentration dependence study of the formation rate of the muon molecules dtμ in equilibrium double D/T and triple H/D/T liquid mixtures of hydrogen isotopes requires an installation consisting of a target of volume 30 cm3 with helium cooling and a thermostabilization system. The temperature of the target, close to 22 K is fixed with an accuracy of 0.1 K.

We determined the parameters of the processes of penetration and diffusion of the hydrogen isotopes through the superalloy EI698 in the 600–1050°K range at pressures up to 100 MPa. It was shown that the penetrating flux is in proportional to √p in the 0.1–100 MPa pressure range.

The correlation parameters describing the simultaneousπ0 and charged particle production in the 5–205 GeV/cπ−p collisions are studied. The linear dependence of the associatedπ0 average multiplicity 〈n0〉n− on the negative particle multiplicity n− in momentum range under consideration is observed. The newπ−p data indicate that the correlations betweenπ0 and charged particles do not depend on the initial state particles. The energy dependence of the correlation integralsf2−− andf20− has been analyzed.

The results of the study of the π+p→K+∑+ (1) and π+p→K+∑+(1385) (2) reactions at 12 GeV/c are presented. The differential cross sections dσ/dt in|tmin

Measurement of the neutron yield of the reaction dt μ → 4 He + μ − + 17.6 MeV , induced by negative muons in a mixture of gaseous D 2 and T 2 , has shown that the rate of muon transfer from deuterium to tritium is λ dt = (2.7 ± 0.9) × 10 8 s −1 and that the lower limit of the formation rate of dt μ molecules is λ dtμ > 10 8 s −1 .

The accelerating complex for the production of the multicharged ion beams up to uranium with a final energy of 300 MeV/amu is described. It is supposed to use a Wideroe type accelerator at the first stage of acceleration (up to 0.59 MeV/amu), a conventional isochronous cyclotron at the second stage (up to 10 MeV/amu), and an isochronous cyclotron with superconducting magnet coils at the final stage. Such a structure of the accelerating complex provides high beam intensity at the full energy of 300 MeV/amu (about 1013 particles per second for uranium), and the intermediate energy of 10 MeV/amu (about 1014 particles per second for uranium). Some preliminary parameters of the accelerator are presented.

The experimental results are presented for ratios of ν-meson inclusive differential cross sections in 10.5 GeV/c π+p, π+D and π+A collisions, RD/p=(dσ/dxF)(π+D→ηX)/ (dσ/dxF)π+p→ηX), RA=(dσ/dxF)(π+D→ηX) in the beam fragmentation region. The results are based on the statistics of ≈ 5 × 104 detected η → 2γ decays. It is shown that the power α in the parametrisation RA ≈ Aα(xf) does not change significantly with xF and its mean value is 0.50±0.02. The lower limit is obtained for the effective coefficient with string tension in the colour string model, κ ⩾ 3 GeV/fm. The observed growth of RA with xF can be explained by an assumption of a neutron halo with the factor H ≈ 4 in the nuclei.

The synchrocyclotron of the Laboratory of Nuclear Problems for 680 MeV protons with a beam intensity of 2.3 mA and beam extraction efficiency of 5-7%, operational now for 30 years, has been under conversion since 1979. The conversion is aimed at making a phasotron with spatial variation of the magnetic field using the building and the magnetic core of the former accelerator. This spatial variation ensures vertical focusing of accelerated particles in the magnetic field growing along the radius and thus enables a reduction in the frequency range of the accelerating voltage which, in turn, results in a circa three-fold increase in the accelerating voltage and the cycle repetition. The conversion includes replacement of the electromagnetic windings, pole tips, accelerator chamber, dee with the resonance line, rotating capacitor, R.F. generator, ion source, beam extraction system, and auxiliary equipment. A computerized control system, based on microprocessors, will also be implemented. This paper reports the status of the conversion to date.

A full-absorption scintillation spectrometer for neutrons (volume of scintillator = 24 1) has been developed and employed in investigations of muon catalysed processes. Its application allows: (a) considerably increasing the rate of accumulation of events; (b) efficiently using muon catalysis multiplicity for fuller and more reliable determination of its parameters; (c) significantly reducing uncertainty in the calculated and experimentally found values of neutron detection efficiency. The device combines good spectrometric properties for neutron energies En = 1–6 MeV and reliable n-γ separation (the degree of separation for a PuBe source ≲ 10−3 starting from an electron energy of 50 keV).

The elastic scattering distribution of negative pions by protons has been measured with a hydrogen-filled diffusion cloud chamber in a magnetic field. In a set of exposures 344 and 941 elastic scattering events were recorded at anglesθ(c.m.s.) > 10°. The total cross-sections for elastic scattering σe1 (128MeV) = (12.8 ± 1.0) 10−27 cm2 and σe1(162 MeV) = (21.4 ± 1.2) 10−27 cm2 were determined by calculating the total length of negative pion tracks in the chamber. The elastic π−-p-scattering angular distributions wwere obtained in the form (the SP-analysis): d σ/ d Ω(128 MeV ) = (1.00±0.08)[(0.55±0.07)+(0.34±0.12) cos θ+(1.30±0.24) cos 2 θ] 10 −27 cm 2 / sr , d σ/ d Ω(162 MeV ) = (1.00±0.06)[(0.93±0.07)+(0.51±0.12) cos θ+(2.28±0.22) cos 2 θ]10 −27 cm 2 / sr . The differential forward scattering cross-sections are equal to (2.20±0.32) 10−27 cm2/sr and (3.73±0.32) 10−27 cm2/sr respectively. The real parts of the forward scattering amplitude (in c.m.s.) have been calculated in units of ℏ/mπc: D_b(128 MeV) = 0.261±0.031 and D_b(162 MeV) = 0.216±0.038. These quantities agree with those calculated from dispersion relations with the coupling constant f2 = 0.08.

This article is devoted to the design of a cyclotron with a spatially varying magnetic field. The basic conclusions of the linear theory of motion of charged particles in a magnetic field of periodic radial and azimuthal structure are given. The theoretical and experimental results of the study of nonlinear resonance close to the center of the accelerator are presented. Formulas are obtained for the calculation of required magnetic field configurations. Methods of shimming, measurement, and stabilization of the magnetic field are suggested. An accelerator designed with pole faces of diameter 120 cm was used for modeling the ion phase motion and for investigating spatial stability. Deuterons were accelerated to an energy of 13 Mev at an accelerating voltage of 5 kv.

Theoretical and experimental results are presented from a study of the effect of ionic space charge on the frequency of the free axial oscillations in an isochronous synchrotron. The axial oscillation frequency was determined by resonance excitation of free oscillations with an external electric field. It is shown that the change in frequency of the axial oscillations as a function of space charge density agrees with the results of the theoretical treatment. An experimental determination was made of the azimuthal dimension of the accelerated particle burst at different radii. The studies were made in the Nuclear Problems Laboratory of the United Institute of Nuclear Studies, on a cyclotron with spatial variation of the magnetic field.

In a diffusion cloud chamber filled with deuterium up to 7.2 atm, 20 events of the heretofore unobserved reaction dμ+d→(ddμ)+→ →3He+n+μ− (2) have been detected. The branching ratio for this reaction and reaction (ddμ)+→t+p+μ− (1) is 1.20±0.37. The estimates of the relative yields of the reaction (ddμ)+→pμ+t (3) and (ddμ)+→ →(3Heμ)++n (4) cause thatw(3)/w(1)

The theoretical and experimental results of an investigation into the effect of the space charge of the ions on the frequency of the free axial oscillations in an isochronous cyclotron are discussed. The frequency of the axial oscillations was determined by using an external electric field to excite a resonance of the free oscillations. It is shown that the axial oscillation frequency varies with the space charge density in accord with the theoretical predictions. The azimuthal extent of the bunch of accelerated particles has been determined experimentally at various radii. The work was carried out at the Laboratory for Nuclear Problems at the Joint Institute for Nuclear Research on a cyclotron with an azimuthal magnetic field variation.

The possibility of constructing a high-efficiency bubble chamber is considered. The principle of operation depends on the production of pressure auto-oscillation conditions in the working fluid. A one-meter propane bubble chamber with a minimum air pressure stabilizer was used to study conditions for exciting and keeping up undamped oscillations in the chamber and conditions for bubble recompression. (A.G.W.)

This article treats the biological action of radiation, the methods and technology of irradiation by heavy charged particles, and the advantages to be gained by using heavy charged particles in radiation therapy and radioneurosurgery. Features of the dose distribution and of the biological action of different radiations are discussed. Estimates of the prospects for using heavy particles in medicine are given and the world data on performed studies are summarized.

Some problems related to the construction of the model of a ring-shaped phasotron with spiral magnetic field structure is considered in this paper. Basic parameters of the designed model are given and the sections of the magnetic system and the accelerator-injector of the model of the ring-shaped phasotron are described.

A new value of the upper limit for the branching ratio of the decay of K 0 S into e + e − has been experimentally obtained using a lead glass detector. The value is BR (K 0 S → e + e − ) −4 (90% CL).

The existence of the Λγ peak between 1300 and 1400 MeV was supported by our measurements. The explanation of this peak by means of the hypothetical Λη (1680 MeV) resonance can be rejected with a 97% confidence level.

Proton beams of the Joint Institute for Nuclear Research (LNP, JINR) Dubna synchrocyclotron and of the proton synchrotron of the Institute for Theoretical and Experimental Physics (ITEP) Moscow have been used for medical and biological purposes since 1967. 58 patients in JINR and 163 in ITEP with various types of malignant tumors have been treated. Results of clinical research showed that use of high energy protons for treatment of malignant tumors is quite expedient and may serve as a good approach developing better means for irradiation in oncological therapy. Proposals for proton and meson beams at the JINR high intensity phasotron and for proton beams at the ITEP medical and biological center are discussed. The ITEP center will consist of 4 cabins for therapy and 2 cabins for radiobiological research, which will permit to treat ~ 100 patients per day.

The mean magnetic field increase along the radius in accordance with relativistic mass increase of the accelerating ions is discussed. The magnetic field increase is necessary for the elimination of non-linear resonance effects at the center of the accelerator. Measurements of the magnetic field were made with an accuracy of plus or minus 1.5 gauss by a nuclear magnetometer. Deuterons were accelerated to an energy of 12 Mev and alpha particles of 24 Mev when the minimum amplitude of the accelerating voltage on the dee was 8 kv. All measurements were carried out with the intensity of the internal beam close to 1 mu a. (B.O.G.)