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The formation of the giant dipole resonance (GDR) in light (A < 40) atomic nuclei is studied. It is shown that the main feature of the GDR in these nuclei is configurational splitting, which is caused by the sharp drop of the deep 0s and 1p shells in 1p- and 2s, 2d-shell nuclei, respectively, and by the approximate spin-isospin SU4 symmetry (1p-shell nuclei). As a result of this a single dipole state is not formed in light nuclei and the GDR is spread over groups of levels in different regions of the excitation energy. The role of this phenomenon in the system of modern ideas about the formation of collective states of nuclei is indicated and problems for further experimental and theoretical study are formulated.

The diffraction dissociation reaction n + p → (pπ−) + p was studied at the Serpukhov accelerator neutron beam in the momentum range 35–65 GeV/c in an electronics experiment. The differential cross sections of the reaction are analysed and presented in the five-dimensional phase space (pn, m∗, t, cosθ∗, φ∗). The backward peak observed in the distribution over if cosθin GJ ∗ in the Gottfried-Jackson frame of if(pπ) is interpreted as a baryon-exchange effect. The angular distribution of the (pπ−) system is compared with Deck-type models.

1. Thin-layer chromatography has been used to show that side reactions are not involved in the addition of aniline to phenyl glycidyl ether (PhGE). 2. The dielectric constant (e) of the medium varies only insignificantly in the course of reaction and is not the factor responsible for autocatalysis in this reaction, which is due to the products formed in primary and secondary PhGE addition to the aniline. 3. Effective third-order rate constants have been evaluated for the reaction of PhGE with aniline and the primary addition products; the factors accounting for the observed alteration of these constants with changes in the concentrations of the original components are discussed.

Construction and operation of high pressure proportional counters designed for pressures up to 92 atm which work in pure hydrogen are described. This type of counter offering track reconstruction as well as energy loss determination will be employed as live-target for low-energy recoil measurements in elastic np scattering.

Kinetics of formation of crosslinked polymers prepared from resorcinol diglycidyl ether (RDGE) and 4,4′-diaminodiphenyl sulphone and relaxation properties were studied by electro-physical methods. A method was proposed for determining the activation energy of this process using typical points on curves showing conductivity in relation to time. By analysing the variation of dielectric constant in the range of phase transition of RDGE a hypothesis was framed concerning the existence in the melt of stable associates with parallel orientation of molecules. It was shown that an increase of solidification temperature restricts the relaxation time of the high temperature process. In polymers obtained with amine deficiency segmental mobility was recorded as defects in the three dimensional network. Crosslinked polymers obtained with amine excess are characterized by structural heterogeneity which is shown in the form of narrow maxima on curves of the temperature dependence of tan δ. It was shown that with excess concentrations of RDGE starting from 1,4 of the stoichiometric, the latter functions as a plasticiser.

The construction and operation of a hydrogen high pressure proportional detector is described. The detector is used as a live target in the experiment on n-p elastic scattering to detect recoil protons with kinetic energy as low as 2 keV.

The oxidation of ASD-4 and AV-000 aluminum powders in the temperature range 293–1773°K has been studied by the thermogravimetry (under conditions of programmed heating), thermal argon desorption, and x-ray phase analysis methods. The stresses generated during heating in the outer oxide films on aluminum particles lead to the formation of cracks in the former, which promotes oxidation of the aluminum. Marked increases have been observed in the oxidation rate and specific surface of the ASD-4 powder at temperatures corresponding to the temperature range of the γ → α-Al2O3 transition. The finding appears to be linked with an increase in the intensity of crack formation during the polymorphic transformation and with enhanced diffusional mobility in the oxide layers.

Using bremsstrahlung from the 35 MeV betatron the 26 Mg( γ , x p) reaction cross section has been obtained in the excitation energy region up to 29 MeV. The role of isospin splitting in the formation of a giant dipole resonance is discussed in the case of light nuclei.

The mechanisms of electrical conduction in polymeric composites with electrically conducting fillers are examined on the basis of effective medium, fluctuation tunnelling, and percolation models. The properties of the conducting fillers — metals, graphite, and technical carbon — are analysed. Factors influencing the electrical conductivity of the composites, in particular the methods of preparation of the filler and of the material, are discussed. The prospects for the utilisation of composites of this type are indicated. The bibliography includes 62 references.

The design and the mass production of the proportional wire chambers for the barrel part of the uranium-gas sampling hadron calorimeter of the L3 detector at the CERN Large Electron-Positron storage ring (LEP) are described. The chambers meet the specific requirements arising from the limited space available to the calorimeter, the radioactivity of uranium, and the physics criteria of good energy and position resolution for incident hadrons. The mass production techniques employed ensured that all of the 371664 chamber cells have uniform response (with 5% accuracy) to ionizing particles. Over 8000 chambers of the same design, in 53 different sizes, were manufactured and tested at the ITEP (Moscow), at the University of Michigan (Ann Arbor) and at the IHEP (Beijing).

The technique of the difference proton spectra is used to study the decay properties of highly excited states of the 58 Ni and 60 Ni isotopes in the energy region of the giant dipole resonance. The proton transition strengths to specific final states from particular initial states have been extracted. Experimental data are interpreted in terms of isospin splitting of the giant dipole resonance.

Mechanical testing and photo-elasticity have been used to study the epoxideamine molecular networks representing the product of the interaction of the diglicidyl ether of resorcinol with metaphenylenediamine and aniline. The temperatures of the α transitions have been determined as a function of the average network molecular weight Mc. It is shown that the networks studied represent the superposing of structures with both positive and negative values of differences in their main polarizibilities. The thermodynamic rigidity of the molecular chains of the branches of the network is evaluated. It is shown that fall in the half-with of the α-process with rise in Mc is apparently associated with decline in the relative role of the small scale relaxation mechanisms.

It has been found that when epoxide resins based on resorcinyl diglycidyl ether and 4,4′-diaminodiphenylsulphone are cured on a metal substrate they peel from it at a certain temperature. It is proposed to characterize the adhesive heat resistance of the resins by this temperature. The causes of change in the adhesive heat resistance with change in curing conditions are analysed. Inclusions were discovered in the matrix of cured resin and these are considered to be undissolved hardener. It was found that there is a correlation between the concentration of these inclusions and adhesive heat resistance.

Results of experimental studies of the performance of the uranium calorimeter with gas sampling detectors are presented. There is further evidence showing the importance of the contribution of the neutron component of a hadronic shower to the detected signal. The response and the resolution of the uranium calorimeter are measured in the momentum range 0.3–6.0 GeV/ c for the different incident particles and different gases that are used in the detectors. For a calorimeter structure with double-gas-detector layers, the correlation between signals from two calorimeters formed by chambers filled with different gas mixtures is measured. The topics that are relevant to the performance of the L3 uranium-gas sampling calorimeter - such as its operation in the magnetic field, the energy dependence of muon response, the uranium noise, as well as the electronics optimization - are discussed.

Deformation-strength properties have been investigated for network polymers based on epoxide-diane oligomers of different MW, and on resole phenol-formaldehyde (PF) oligomers in the glassy and the rubber like states. It was found that tensile properties of the network polymers depend neither on the thermal prehistory of solutions of the starting oligomers in ethylcellosolve, nor on the thickness of samples in the interval 20–250 μm. Density values of the crosslinked network polymers increase with increasing MW of the oligomers at the expense of curing both via functional endgroups, and via functional groups in the middle of the oligomer chains. Methods of dielectric relaxation and of differential scanning calorimetry were used to determine glass-transition temperatures of the polymers: where Mc is high, Tg is not a function of Mc; Tg rises as Mc decreases and as Mc values approximate to the length of statistical Kuhn segments of epoxide-diane oligomers.

Cross sections for inclusive ${\ensuremath{\pi}}^{0}$ production at large transverse momentum ${p}_{T}$ were measured in ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$p, ${\ensuremath{\pi}}^{+}$p, and pp collisions at 300 GeV/c. The cross-section ratio \ensuremath{\sigma}(${\ensuremath{\pi}}^{\ensuremath{-}}$p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$X)/\ensuremath{\sigma}(${\ensuremath{\pi}}^{+}$p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$X) was found to be consistent with unity in the ${p}_{T}$ region of 1 to 5 GeV/c. The cross-section ratio \ensuremath{\sigma}(${\ensuremath{\pi}}^{+}$p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$X)/\ensuremath{\sigma}(pp\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$X) however is growing with increasing ${p}_{T}$ and increasing ${\ensuremath{\pi}}^{0}$ c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.

The results of the total cross section measurements of neutrons on protons, deuterons and nuclei C, O, Al, Cu, Sn, Pb in the energy range of 28–54 GeV are reported.

The neutron-proton elastic differential cross section has been measured for incident momenta between 10 and 70 GeV/c and for values of the momentum transfer squared between 0.1 and 2.8 (GeV/c) 2 . The forward peak and the break at about ∣ t ∣ = 1 (GeV/ c ) 2 are very similar to corresponding pp data.

The performance of a uranium gas sampling hadron calorimeter is described. It has been observed that the hydrogen content of the gas mixture plays an important role in defining the behaviour of this type of calorimeter. The low-energy neutrons emerging from a hadron cascade are detected much more efficiently in a hydrogenous gas; thus leakage or containment of these neutrons becomes an important feature of the calorimeter setup.

As part of the NA24 experiment at the CERN-SPS a photon position detector serves to separate direct photons from abundantly produced π0 decay photons: electromagnetic showers are measured with an energy- and position-resolution sufficiently good to give a two-gamma resolving power of 1.2 cm. The shower detector covers 3 × 3 m2 and consists of 12 layers of triangular proportional tubes (7.73 mm pitch) sandwiched with lead (altogether 9.6X0). For eight layers the analog information is provided by an ADC system. Ambiguities are resolved by the digital information of four additional layers inclined by 45°. Prototypes were built in order to test gas mixtures and electronics. The electromagnetic shower development in the PPD and the prototypes are reproduced by Monte Carlo calculations. The homogeneity of the PPD has been checked by calibration measurements.

A gas sampling calorimeter with uranium absorbers was built and tested in a beam of pions and electrons of 1 to 6 GeV/ c . As far as the detection of electromagnetic showers is concerned, no difference between uranium and a conventional absorber is found. The energy dependence of the resolution of the calorimeter for hadrons is given for 4.5 and 9 mm sampling. The measured π e ratio is 0.83±0.03.

Cross sections for inclusive direct photon production in ..pi../sup -/p, ..pi../sup +/p, and pp collisions at 300 GeV/c are measured at transverse momenta p/sub T/ up to 7 GeV/c (x/sub T/ = 0.6). For ..pi../sup -/p..--> gamma..X also the rapidity distribution is presented. The cross-section ratio sigma(..pi../sup -/p..--> gamma..X)/sigma(..pi../sup +/p..--> gamma..X) is found to be 1 at p/sub T/ = 4 GeV/c and rises with increasing p/sub T/. This observation signals the occurrence of valence-quark--antiquark annihilation. The results are in good agreement with QCD predictions.

The response of a sampling total absorption counter (STAC) to protons, neutrons, pions, and electrons with incident energies up to 60 GeV is described. A good linearity was observed, and for protons a resolution of ±6% at 60 GeV/ c could be achieved. The absolute fwhm rises slowly with energy from 4.5 GeV/ c at 10 GeV/ c to 7.2 GeV/ c at 60 GeV/ c . The fraction of the energy deposited in the scintillator by incident π + and e + is on the average 9% and 50% higher than that deposited by protons.

With bremsstrahlung from a 35 MeV betatron, the 24,26 Mg( γ , x n) reaction cross sections are obtained. The role of various factors in the formation of the giant resonance in 24 Mg and 26 Mg is considered.

The angular and energy distributions were investigated and the photoproton yields measured from Rh, Pr, W, Pt and Pb for the maximum bremsstrahlung energies 22.5 and 33.5 MeV. The maxima of the cross sections for the production of photoprotons were found to be at energies above 22 MeV and the absorption of γ-quanta in this energy region by heavy nuclei was found to have chiefly a quadrupole character. The contribution of the quadrupole absorption increased with Z.

From the measurement of prompt photon production at large transverse momentum one can obtain fairly clean information about constituent scattering dynamics, since the photon is a direct participant of the constituent scattering process. With the use of pion beams, the experiment aimed at the observation of the QCD-annihilation process. Rather precise measurements of direct photon cross sections in this experiment provide a good test of QCD, in particular since next to leading order terms are included in the QCD predictions.