Measurement of the decay-probability of metastable hydrogen by two-photon emission

The two-photon-decay probability of the metastable 2² S_{$\text{1}\text{2}$} level of hydrogen has been measured. The result A(λ)dλ = 1.5 sec^?1 ± 43% in the spectral range dλ = (255.4?232)nm ± 5% is in agreement with the theoretical prediction.     

Novel modified ultrasonication technique for the extraction of lycopene from tomatoes

Lycopene extraction was carried out via the ultrasonic assisted extraction (UAE) with response surface methodology (RSM). Sonication enhanced the efficiency of relative lycopene yield (enhancement of 26% extraction yield of lycopene in 6 replications at 40.0 min, 40.0 °C and 70.0% v/w in the presence of ultrasound), lowered the extraction temperature and shortened the total extraction time. The extraction was applied with the addition of oxygen-free nitrogen flow and change of water route during water bath sonication. The highest relative yield of lycopene obtained was 100% at 45.0 °C with total extraction time of 50.0 min (30:10:10) and ratio of solvent to freeze-dried tomato sample (v/w) of 80.0:1. Optimisation of the lycopene extraction had been performed, giving the average relative lycopene yield of 99% at 45.6 min, 47.6 °C and ratio of solvent to freeze-dried tomato sample (v/w) of 74.4:1. From the optimised model, the average yield of all-trans lycopene obtained was 5.11 ± 0.27 mg/g dry weight. The all-trans lycopene obtained from the high-performance liquid chromatography (HPLC) chromatograms was 96.81 ± 0.81% with 3.19 ± 0.81% of cis-lycopenes. The purity of total-lycopene obtained was 98.27 ± 0.52% with β-carotene constituted 1.73 ± 0.52% of the extract. The current improved, UAE of lycopene from tomatoes with the aid of RSM also enhanced the extraction yield of trans-lycopene by 75.93% compared to optimised conventional method of extraction. Hence, the current, improved UAE of lycopene promotes the extraction yield of lycopene and at the same time, minimises the degradation and isomerisation of lycopene.     

Coupling of one and three quasiparticles to a collective core projected from quadrupole coherent states

The excitation energies and the electromagnetic properties of some odd-mass isotopes of Pt are treated in the framework of a particle-core coupling model. The collective motion of the core is treated by the coherent state model (CSM). A system of interacting shell model nucleons is coupled to the core through aλ-pole-λ-pole term withλ=0, 2, 4. The coupled system is treated alternatively in the strong and weak coupling limit. Numerical applications to the isotopes^189,191,193Pt show a good agreement with the available data. The backbending of the yrast band is interpreted as being caused by the intersection of the one and three quasiparticle bands.     

Die Hyperfeinstruktur des übergangs Ag I, λ=19372 å

The hyperfinestructure of the transition AgI, 4d ⁹ 5s ^{2 2} D _3/2-4d ¹⁰ 5p ² P _1/2,λ=19372 å has been investigated with a photoelectric recording Fabry-Perot interferometer and digital data processing. The isotope shiftδ Ν _IS and the magnetic splittings factorsA have been determined to beδ Ν _IS=35,77 (12) mK,A(¹⁰⁹Ag, 5p ² P _1/2)=?7,00 (45) mK, andA(¹⁰⁹Ag, 4d ⁹ 5s ^{2 2} D _3/2)=?12,18 (23) mK. The influence of shielding effects on the value of the volume effect of the isotope shift and the influence of core polarisation on the splitting factors are discussed.     

Hyperfeinstrukturuntersuchungen mit einem sphärischen Fabry-Perot-Interferometer mit internem Absorptionsatomstrahl im Tm I- und Eu I-Spektrum

A spherical Fabry-Perot spectrometer with an absorbing atomic beam passing the interior of the interferometer is described. By use of the internal beam it is possible to reduce the amount of material needed for the atomic beam source to a few milligrams per hour. The set-up is especially suitable for hyperfine structure and isotope shift investigations. For the photoelectric recording of the signal the geometrical distance between the spherical mirrors was changed using the piezoelectric effect. In order to reduce the influence of the intensity distribution of the light sourceI ₀(λ) the ratio [I ₀(λ)-I(λ)]/I ₀(λ) was measured, whereI ₀(λ)=I ₀(λ) exp (—V·k(λ)·d) is the observed intensity with absorbing atoms between the mirrors, andV the increase of the absorption signal due to the multiple reflections of the light through the atomic beam (V≈75). For an accurate and easy evaluation of the data this ratio was measured by a digital voltmeter and punched into paper tape. The small line width of the absorption profile obtained in the experiments with Tm and Eu enabled us to measure hyperfine distances of the order of 5 · 10^?3 cm^?1 to 20 · 10^?3 cm^?1 with an error not exceeding 0.1 · 10^?3 cm^?1 in some cases. From the measurements theA-factors for five levels of the configurations 4f ¹³6s 6p and 4f ¹²5d 6s ² in Tm I and theA- andB-factors of the stable Eu isotopes of the 4f ⁷ 6s 6p y ⁸ P _5/2level in Eu I were determined.     

Large deviations and Lifshitz singularity of the integrated density of states of random Hamiltonians

We consider the integrated density of states (IDS) ρ_∞(λ) of random Hamiltonian H_ω=?Δ+V_ω, V_ω being a random field on ? ^d which satisfies a mixing condition. We prove that the probability of large fluctuations of the finite volume IDS |Λ|^?1ρ(λ, H_Λ(ω)), Λ ? ? ^d , around the thermodynamic limit ρ_∞(λ) is bounded from above by exp {?k|Λ|},k>0. In this case ρ_∞(λ) can be recovered from a variational principle. Furthermore we show the existence of a Lifshitztype of singularity of ρ_∞(λ) as λ → 0⁺ in the case where V_ω is non-negative. More precisely we prove the following bound: ρ_∞(λ)≦exp(?kλ^?d/2) as λ → 0⁺ k>0. This last result is then discussed in some examples.     

Paramagnetic resonance of V in tetragonal GeO2

Anisotropic g and A tensors are found for V⁴⁺ in single crystal tetragonal GeO₂. The orbital mixing parameter λ, normalized radial average 〈1/r³〉/N and core polarization x/N are calculated, and λ is not anomalously low as reported from polycrystalline measurements.     

Weyl’s Gauge Argument

The standard $\mathbb{U}(1)$ “gauge principle” or “gauge argument” produces an exact potential A=dλ and a vanishing field F=d ² λ=0. Weyl (in Z. Phys. 56:330–352, 1929; Rice Inst. Pam. 16:280–295, 1929) has his own gauge argument, which is sketchy, archaic and hard to follow; but at least it produces an inexact potential A and a nonvanishing field F=dA≠0. I attempt a reconstruction.     

Preparation of Ru-loaded CdS/Al-HMS nanocomposites and production of hydrogen by photocatalytic degradation of formic acid

The composite of aluminum-substituted mesoporous silica (Al-HMS) molecular sieve coupled with CdS (CdS/Al-HMS) was prepared by template, ion exchange and sulfurization reactions. The result of low angle XRD patterns showed that the low content of 2.5 wt% CdS is incorporated inside Al-HMS channels. The results of diffuse reflectance UV-visible spectra and fluorescence emission spectra exhibited that the absorption edge and photoluminescence peak for CdS/Al-HMS are blue-shifted about 75 nm and 40 nm in comparison to bulk CdS, respectively. The activities of hydrogen production by photocatalytic degradation of formic acid were evaluated under visible light irradiation (λ ≥ 420 nm) and the CdS/Al-HMS loaded 0.07 wt% Ru showed the highest H₂ evolution at a rate of 3.7 mL h⁻¹ with an apparent quantum yield of 1.2% at 420 nm.     

Search for heavy quasistable leptons

Negative results of a search for heavy quasistable charged leptons at the IHEP accelerator are reported. For the selection of heavy leptons a system of scintillation and gas ?erenkov counters was used. The upper limit estimations of the differential cross sections for heavy lepton production in pN collisions at E_p = 70 GeV are, for example, d²σ/dpω (p = 30 GeV/c, θ = 2 mrad, 1 ? M_λ ? 4.8 GeV) = 4.10^?38 cm²/sr · GeV. The results of the present work, together with the data on muon pair production in nucleon-nucleon interactions, show that there are no heavy charged leptons with masses from 0.55 GeV (τ_λ > 7 · 10^?10 sec) up to 4.5 GeV (τ_λ > 3 · 10^?8 sec).     

Deperturbation study of the 0–1 band of the d3Πi-b3Πr transition of the SiO molecule

The structure of the (0–1) band of the d³Π_i-b³Π_r system of SiO has been photographed under high resolution with a chemiluminescent flame source, and a rotational analysis has been carried out. All theoretically predicted 27 branches of the d³Π_i-b³Π_r transition have been identified. The upper-state level is shown to be perturbed by the v = 23 level of the A¹Π state. Due to mixing of the A¹Π with the d³Π, the (23-1) band of the A¹Π-b³Π_r transition has also been observed. The deperturbed molecular constants of the d³Π_i and A¹Π levels have been evaluated.     

Experimental investigation of muon-catalyzed dt fusion at cryogenic temperatures

An experimental investigation of muon-catalyzed fusion (μCF) in gaseous, liquid and solid mixtures of deuterium and tritium was performed. The target conditions included the range of densities of 0.03 ≲ φ ≲ 1.5, tritium concentrations of 2% ≲ c_t ≲ 90% and temperatures of 13 ≲ T ≲ 40K. The study was based on the analysis of observed cycling rates extracted from the measured time distributions of the fusion neutrons. For the first time, the density dependence of the rates λ_(dtμ)d⁰ for the dtμ molecule formation in collisions of tμ atoms in the lower (F=0) hyperfine state with D₂ molecules was determined experimentally. Evidence for the proposed effects of below-threshold resonances on molecular formation was found. Measurements at low temperatures in mixtures of different molecular compositions revealed a clear predominance of the λ_(dtμ)d⁰ formation rate. The probability q_1s for dμ atoms to reach the ground state was determined as a function of density and tritium concentration.     

Angular correlation measurements in the B10(d,p,γ)B11 reaction

Proton gamma angular correlations through the 6.76 and 8.92 MeV excited states of B¹¹ are measured at deuteron bombarding energies from 1.6 to 2.4 MeV. The correlations are measured at laboratory proton scattering angles 35? in both reaction and azimuthal planes. The correlation coefficientA ₂ ⁰ and the distortion parameterλ are calculated. A systematic shift of the symmetry axis from the recoil direction is observed. This shift tends to zero asE _d→Q. For the 8.92 MeV excited state of B¹¹(Q=0.32 MeV) the distortion parameterλ is close to the plane wave limit. The possible values of incoming channel spins as well as gamma-ray multipole mixing ratio for the 6.76 and 8.92 MeV states are obtained.     

Energy of a muonic X-ray transition measured with a crystal spectrometer

The wavelength of the $\text{3}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{?2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ muonic X-ray transition in ²⁸Si has been measured relative to the wavelength of the 84 keV gamma ray from a ¹⁷⁰Tm source. The result is λ^Si/λ^Tm = 1.099675 (39). Using the reported value for λ^Tm we find (λ_exp^Si-λ_th^Si)/λ_th^Si = (?9±35) × 10^?6.     

Experimental determination of isotope shifts in Mg I

The isotope shift in the Mg l transitionsλλ 5167, 5172 and 5183Å (3s3p ³ P-3s4s ³ S) andλ 5528 Å (3s3p ¹ P 3s4d ¹ D) has been measured for the isotopes²⁴Mg,²⁵Mg and²⁶Mg. The hyperfine structure of theλ 5167 Å line has been studied and theA andB factors for the 3s4s ³ S ¹ level in²⁵Mg determined. The measurements were made with separated isotopes using a scanning Fabry-Perot interferometer.     

Resonanzstreuung von Licht in magnetischen und elektrischen Feldern zur Untersuchung der Hyperfeinstruktur des 7d 2 D 3/2-Terms im Thallium I-Spektrum

Observing the resonance fluorescence of the transition 7d ² D _3/2-6p ² P _1/2 (λ=2379 Å) in the Tl I-spectrum the level crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure and the Stark effect of the 7d ² D _3/2-state. For electric field strengthsE?25 kV/cm the Stark shifts are considerably greater than the hyperfine splitting. Therefore the crossing signals for the case of decoupled hyperfine structure could be detected. The following values of the magnetic hyperfine constantA and the Stark parameterβ were deduced: ¦A¦=55(1) Mc/sec·g _J /0.8, ¦β¦=0.20(4) Mc/sec/(kV/cm)²·g _J /0.8 andA/β>0. The widths of the signals yielded the mean lifetimeτ=2.7(5)·10^?8 sec· 0.8/g _J . Sign and values ofA andβ are discussed.     

Some aspects of ultra-relativistic heavy-ion collisions, complex forms of strangeness

The capabilities of the detectors STAR at RHIC and ALICE at LHC for measuring complex forms of strangeness, in the mid rapidity region, are examined as a function of the lifetime of these objects. The simulations are run on the basis of instrumental performances of these detectors as well as on recent theoretical speculations. Particular emphasis is put on the case of the H ⁰ (a 2u2d2s quark bag or alternately two coupled A⁰).     

Cross-sections of high energy nuclear reactions

Cross-sections of high-energy hadron-nucleus reactions σ _h (A) are investigated using ther optical model. A closed formula is drived for σ _h (A); itsA-dependence agrees with the rms radius of the Fermi distribution of nuclear matter. The properties of the radius parameter and the absorption mean free pathλ _h are investigated using Serpukhov data forp, π^α,K ^± , and \(\bar p\) . It is foundλ _p =1.44 ± 0.23 fm ～-1/m _π andλ _π =2.14 ± 0.21 fm forp and π-reactions, respectively; withλ _π /λ _p ?3/2 as expected from quark-counting. The approach extended to heavyion (HI) reactions leads to a formula of Bradt-Peters type, with an overlapping parameter decreasing withA. Analyses of HI data of LBL and ISR with this formula are presented.     

Magnetism and 166Er Mössbauer spectroscopy of Er2−xPrxCo17

The bulk magnetic properties and ¹⁶⁶Er Mössbauer spectra of Er_2?xPr_xCo₁₇ pseudo-binaries are reported. Incorporation of Pr into Er₂Co₁₇ increases the anisotropy field (H_A) and the saturation magnetization, while resulting in only a slight (5%) decrease in the Curie temperature. The quadrupole interaction deduced from the Mössbauer spectrum suggests that Pr preferentially substitutes for Er in Er₂Co₁₇ at the 2d site. The rise in H_A is a consequence of the preferential substitution, which occurs because spatial constraints at the 2d site are less for the larger Pr³⁺ ion. Coupling between Er-Co and Pr-Co is found to be antiferromagnetic and ferromagnetic, respectively.     

Effect of the spin-orbit interaction of Ni2+ ions with a triplet orbital ground state on the magnetostriction of NiFe0.5Cr1.5O4 ferrite

The magnetization σ and the longitudinal (λ_∥) and transverse (λ_⊥) magnetostrictions of the NiFe_0.5Cr_1.5O₄ ferrite containing the tetrahedral ions Ni²⁺ with the triplet orbital ground state have been investigated for the first time at a temperature of 4.2 K in fields up to 55 kOe. It is revealed that the NiFe_0.5Cr_1.5O₄ ferrite exhibits an anomalously large magnetic anisotropy (H _c=12.5 kOe) and magnetostrictions (λ_∥≈?870×10^?6 and λ_⊥≈800×10^?6). In strong fields, the magnetostrictions λ_∥ and λ_⊥ are found to be anisotropic in character; i.e., the susceptibility Δλ_∥p and Δλ_⊥p. The conclusion is drawn that the studied compound is characterized by two paraprocesses: one paraprocess in the B sublattice has an exchange nature, and the second process in the A sublattice is due to the spin-orbit interaction of Ni _A ²⁺ ions.