Anisotropic response measurements of ZnWO4 scintillators to neutrons for developing a direction-sensitive dark matter detector

The scintillation yields of ZnWO$_4$ crystals change depending on the incident direction of particles. This property can be used as a direction-sensitive dark matter detector, so we investigated the ZnWO$_4$ light yields ratio of neutron-induced nuclear recoils to gamma-ray-induced electron recoils (quenching factor). Two surfaces almost perpendicular to the crystal axis of ZnWO$_4$ were irradiated with a quasi-monochromatic neutron beam of 0.885 MeV, and the quenching factors of both surfaces for the oxygen-nucleus recoil in the ZnWO$_4$ crystal were measured. The obtained quenching factors of the two surfaces were $0.235 \pm 0.026$ and $0.199 \pm 0.020$, respectively, confirming 15.3% anisotropy.

Breakup of oxygen nucleus on isotopes of hydrogen and nitrogen nuclei in collisions with protons at 3.25A GeV/c

Phenomenological analysis of breakup of oxygen nuclei on fragments with the charges one and seven in collisions with protons at 3.25[Formula: see text][Formula: see text]GeV/[Formula: see text] was conducted using the Monte Carlo model of isotropic phase space. For the first time, the contributions of mechanism of diffractive breakup of oxygen nucleus and that of quasi-elastic knocking out of one of the protons of oxygen nucleus by a proton target into channel of formation of proton fragment and [Formula: see text]N nucleus with conservation of recoil proton in final state were determined. Cross-section of diffractive breakup of oxygen [Formula: see text]O nucleus on [Formula: see text]N nucleus and proton fragment and that of diffractive breakup of [Formula: see text]O nucleus on nuclei [Formula: see text]N and 2H were estimated for the first time in [Formula: see text]O[Formula: see text] collisions at 3.25[Formula: see text][Formula: see text]GeV/[Formula: see text].

Breakup of 16O nucleus onto C and He isotopes by protons at incident momentum of 3.25AGeV/c

Phenomenological analysis of breakup of oxygen nuclei on fragments with charges two and six in collisions with protons at [Formula: see text][Formula: see text]GeV/[Formula: see text] was conducted using the Monte Carlo (MC) model of isotropic phase space. For the first time, the contributions of mechanism of diffractive breakup of oxygen nucleus, and that of quasi elastic knocking out of one of the [Formula: see text] clusters of oxygen nucleus by a proton target, into channel of formation of [Formula: see text] particle and [Formula: see text]C nucleus with conservation of recoil proton were determined in final state. The substantial role of [Formula: see text] cluster structure of initial nucleus in processes of fragmentation of oxygen nuclei in peripheral interactions with protons was revealed in experiment.

Some peculiarities of formation of 4He nuclei in 16Op collisions at 3.25A GeV/c

The new experimental data on dependences of the mean multiplicities and kinematical characteristics of 4 He nuclei, formed in 16 O p collisions at 3.25A GeV/c, on degree of excitation of the fragmenting nucleus are presented. It is shown that the initial (α cluster) structure of oxygen nucleus is retained at small excitation levels. It is established that the kinematical characteristics of 1 H , 2 H , 3 H and 3 He fragments do not depend on availability or absence of α particles in a collision event, which indicates the independence of mechanisms of formation of such fragments and 4 He nuclei.

Characteristics of Electron Density Distributions in Metal Oxides

The electron density distributions in a series of metal oxides are calculated using the DV-Xα molecular orbital method. It is found that the logarithm of the electron density, logρ(r), decreases with the distance, r, from the oxygen nucleus, while keeping a constant slope relevant to oxygen atom. The magnitude of the slope is about 15.75 for O-1s electrons, and about 6.61 for O-2s, 2p electrons, being nearly close to the respective values of 16 and 8, expected from the radial distribution functions of hydrogen-like atom containing only one electron. The extent of the region for the O-2s, 2p electrons changes with metal species in the oxides, but the slope remains unchanged. Furthermore, it is shown that the nature of the chemical bonding is well represented in log (ρ minZ-3) vs. 2(Z/n) rmin</su>b plots, where ρmin is the minimum electron density, rmin is the distance r at ρmin, Z is the atomic number, and n is the principal quantum number.