Resonance production in the reaction π±p→Ks0K±p at 30 and 50 GeV/c

The mass and momentum transfer spectra of the charged $\text{K}\text{K}$ system produced in the reaction π^±p→K_s⁰K^±p are analyzed. The data have been collected at the CERN SPS with the Geneva-Lausanne two-arm, non-magnetic spectrometer at 30 and 50 GeV/c incident momenta. The general features of the reactions at these energies and the results of partial-wave analyses of the two kaon system are presented.The channel is dominated by the diffractive production of even spin resonances. The spin 4 recurrence of the A₂(1320) is clearly observed at 2040 MeV (Γ=380 MeV. A new resonance is observed with a mass M=2450MeV and a width Γ=400 MeV; the quantum numbers of this state are found to be I^G(J^PC)=1^?(6++). The analysis also shows the decay of the decay of the meson ?′(1600) through the $\text{K}\text{K}$ channel at both energies.The production amplitudes are determined both as a function of the $\text{K}\text{K}$ effective mass and of the momentum transfer. Isoscalar natural parity exchange is dominant. The energy dependence between 10 and 50 GeV/c is shown to be well described by a Regge pole model based on the f-dominated pomeron hypothesis. We compare the production mechanisms of the 2⁺ resonances A₂(1320) and K¹(1430). Finally, we estimate the $\text{K}\text{K}$ branching ratios of the spin 4 A₂(2040) and spin 6 A₂(2450) resonances.     

Comments on the presence of a peak in the static structure factor of an electron liquid

Emphasis is laid on the fact that the peak in the static structure factor S(k) observed in a recent experiment at k≈2k_F for conduction electrons in beryllium agrees well with the one predicted by us theoretically some time back. The error in the calculation of the pair correlation function g(r) using the experimental data on S(k) is pointed out. The position of the peak obtained in our g(r) clearly indicates that the effect of electron correlation is to condense into a Wigner lattice at a distance equal to the average interparticle separation rather than making a Mott type transition to an atomic-like state.     

Die Abtrennung des metachromatischen Bestandteils von Methylenblau und Chondroitinsulfat durch Ultrazentrifugation

Ohne Zusammenfassung     

Stress in polycrystalline GaN films prepared by r.f sputtering

Undoped, Be-doped and Si-doped polycrystalline GaN films were deposited by R.F. sputtering onto fused silica substrates. The films were deposited at various deposition temperatures ranging from 300 K to 623 K and characterized by optical measurements while the microstructural information was obtained from SEM and XRD studies. The compositional study for the GaN film was carried out using SIMS. Residual stresses in these films were evaluated from the band tail of the absorption spectra as well as from direct measurements of hardness by commercially available depth sensing indentometer. It was observed that undoped GaN films had the highest hardness followed by that for Be-doped and Si-doped films. The values of hardness obtained form the above optical measurement tallied quite well with those obtained from direct indentation measurement.     

Excited state property of hardly photodissociable heme-CO adduct studied by time-dependent density functional theory

While most of CO-bound hemes are easily photodissociated with a quantum yield of nearly unity, we occasionally encounter a CO-heme which appears hardly photodissociable under the ordinary measurement conditions of resonance Raman spectra using CW laser excitation and a spinning cell. This study aims to understand such hemes theoretically, that is, the excited-state properties of the five-coordinate heme-CO adduct (5cH) as well as the 6c heme-CO adduct (6cH) with a weak axial ligand. Using a hybrid density functional theory, we scrutinized the properties of the ground and excited spin states of the computational models of a 5cH and a water-ligated 6cH (6cH-H(2)O) and compared these properties with those of a photodissociable imidazole-ligated 6cH (6cH-Im). Jahn-Teller softening for the Fe-C-O bending potential in the a(1)-e excited state was suggested. The excited-state properties of 6cH-Im and 5cH were further studied with time-dependent DFT theory. The reaction products of 6cH-Im and 5cH were assumed to be quintet and triplet states, respectively. According to the time-dependent DFT calculations, the Q excited state of 6cH-Im, which is initially a pure pi-pi state, crosses the Fe-CO dissociative state (2A') without large elongation of the Fe-CO bond. In contrast, the Q state of the 5cH does not cross the Fe-CO dissociative state but results in the formation of the excited spin state with a bent Fe-C-O. Consequently, photoisomerization from linear to bent Fe-C-O in the 5cH is a likely mechanism for apparent nonphotodissociation.     

"Safe" Coulomb excitation of 30Mg

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."     

New experimental results on the interference of the states of the hydrogen atom due to long-range interaction with the metal surface

The interference of the 2P state of the hydrogen atom due to unknown long-range interaction with the metal surface (Sokolov effect) has been studied by an atomic interferometer. In contrast to previous experiments, where an atomic beam passed through slits in metal plates, a beam in the presented experiments passes at a given distance from the edges of the plates. It has been found that the interference is clearly observed if two plates are located on the same side of the beam. However, this interference disappears if one plate is displaced to the opposite side. This result cannot be explained in the framework of the available hypotheses on the nature of the effect under investigation.     

Surface reconstruction and decahedral structure of bimetallic nanoparticles

We report on energetic surface reconstruction phenomena observed on bimetallic nanoparticle systems of AuPd and AuCu, similar to a resolidification effect observed during the cooling process in lead clusters. These binary alloy nanoparticles show the fivefold edges truncated, resulting in [100] facets on decahedral structures, an effect largely envisioned and reported theoretically, with no experimental evidence so far. We demonstrate experimentally as well as by computational simulations that this new eutectic structure is favored in such nanoalloy systems.