A model for the acceptor state in II–VI compounds

The binding energy and the spatial distribution of an acceptor in an ionic semiconductor are calculated on the Anderson model with three parameters. The result is applied to the case of Li⁺, Na⁺, Cu⁺ and Ag⁺ in II–VI semiconductors. The parameters are evaluated by the dielectric theory of a chemical bond. It is shown that Li⁺ in ZnO, CdS, and CdSe forms an acceptor state with a larger amplitude at nearest-neighbor anion sites than at an impurity site; while Cu⁺ and Ag⁺ in Zn and Cd compounds have the opposite properties. The Na⁺ ion forms an acceptor state more localized densely at the impurity site in Zn compounds and vice versa in Cd compounds.     

The mass of 18C from a heavy ion double-charge-exchange reaction

The mass of ¹⁸C has been measured using the double-charge-exchange reaction ⁴⁸Ca(¹⁸O, ¹⁸C)⁴⁸Ti at an ¹⁸O energy of 112 MeV. The ¹⁸C ions were detected at the focal plane of a magnetic spectrometer. The mass excess of ¹⁸C was found to be 24.923 ± 0.030 MeV, and the first excited state was observed at an excitation energy of 1.62 ± 0.02 MeV. At the same time, an independent measurement of the mass excess of ¹⁷C was obtained from the ⁴⁸Ca(¹⁸O, ¹⁷C)⁴⁹Ti reaction, and the value 21.039 ± 0.020 MeV is in excellent agreement with an earlier measurement. The first excited state of ¹⁷C is at 295 ± 10 keV.     

Variation of radon concentrations in soil and groundwater and its correlation with radon exhalation rate from soil in Budhakedar, Garhwal Himalaya

Radon was measured in soil-gas and groundwater in the Budhakedar area of Tehri Garhwal, India in summer and winter to obtain the seasonal variation and its correlation with radon exhalation rate. The environmental surface gamma dose rate was also measured in the same area. The radon exhalation rate in the soil sample collected from different geological unit of Budhakedar area was measured using plastic track detector (LR-115 type II) technique. The variation in the radon concentration in soil-gas was found to vary from 1098 to 31,776 Bq.m⁻³ with an average of 7456 Bq.m⁻³ in summer season and 3501 to 42883 Bq.m⁻³ with an average of 17148 Bq.m⁻³ in winter season. In groundwater, it was found to vary from 8 to 3047 Bq.l⁻¹ with an average value 510 Bq.l⁻¹ in summer and 26 to 2311 Bq.l⁻¹ with an average value 433 Bq.L⁻¹ in winter. Surface gamma dose rate in the study area varied from 32.4 to 83.6 μR.h⁻¹ with an overall mean of 58.7 μ-R.h⁻¹ in summer and 34.6 to 79.3 μR.h⁻¹ with an average value 58.2 μR.h⁻¹ in winter. Radon exhalation rate from collected soil samples was found to vary from 0.1 × 10⁻⁵ to 5.7 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ with an average of 1.5 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ in summer season and 1.7 × 10⁻⁵ to 9.6 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ with an average of 5.5 × 10⁻⁵ Bq.kg⁻¹.h⁻¹. A weak negative correlation was observed between radon exhalation rate from soil and radon concentration in the soil. Radon exhalation rate from the soil was also not found to be correlated with the gamma dose rate, while it shows a positive correlation with radon concentration in water in summer season. Inter-correlations among various parameters are discussed in detail.      

The effect of codopants on spectral-kinetic characteristics of luminescence of scintillation glasses doped with terbium ions

The effect of Ce³⁺ and Pr³⁺ ions on spectral-kinetic characteristics of luminescence of lithium–phosphate–borate glasses is studied. It is shown that terbium ion luminescence caused by transitions from ⁵D₃ and ⁵D₄ multiplets to the ground 7FJ term is detected in samples containing Tb³⁺/Ce³⁺ and Tb³⁺/Pr³⁺. It has been found that an increase in the concentration of cerium ions from 0.2 to 1 wt % leads to an increase in the intensity of main luminescence bands of terbium ions. In Tb³⁺/Pr³⁺ glasses, a decrease in the relative light yield is observed with an increase in the concentration of Pr³⁺ ions. Processes of energy transfer between Tb³⁺/Ce³⁺ and Tb³⁺/Pr³⁺ ions are discussed.     

Investigation of 228Th in the (α, α'2n) reaction

The ²³⁰Th(α, α'2n)²²⁸Th reaction at E_α = 56 MeV was used to investigate states of moderately high spin in ²²⁸Th. Conversion electron and e^?-γ coincidence measurements were carried out, where the electrons were detected with an iron-free orange spectrometer. The ground state and low-lying K^π = 0^? rotational bands were observed up to I^π = 14⁺ and 13^?, respectively. The data are interpreted in terms of an ω-expansion for the ground-state rotational band, and an octupole vibrational band distorted by the Coriolis coupling to the K^π ? 1^? excitations for the K^π = 0^? band.     

Final state signatures ine + e −→H 0 l + l −

The experimental signatures of the production of the Higgs boson in the processe ⁺ e ^?→H ⁰ l ⁺ l ^? are studied. The differential cross section is given as a function of the energy of one of the leptons in an analytic form for an arbitrary collision energy and general acceptance cuts.     

A study of the states of 30Si with the 28Si(t,p)30Si and 29Si(d,p)30Si reactions

The excitation energies of the levels in ³⁰Si have been measured up to an excitation of 9.46 MeV with the ²⁸Si(t, p)³⁰Si reaction at a triton energy of 6.0 MeV. Angular distributions have been measured of proton groups from the ²⁸Si(t, p)³⁰Si and ²⁹Si(d, p)³⁰Si reactions in a multi-angle magnetic spectrograph. Triton bombarding energies of 10.5 and 12.1 MeV were used and the deuteron incident energy was 10.0 MeV. States in ³⁰Si up to an excitation of 8 MeV were observed. Spins and parities of several states have been assigned using an empirical method for the (t, p) results and using a DWBA analysis for the (d, p) distributions. Spectroscopic factors for twelve states were obtained from the latter analysis. Two of these disagree with theoretical predictions. The state previously reported at an excitation of 6.63 MeV in ³⁰Si was observed to be formed by a strong L = 0 transition in the (t, p) reaction and also by a strong l = 1 transition in the (d, p) reaction. We deduce that there are two closely spaced states at about this excitation, one having a spin and parity of 0⁺ and the other 0^?, 1^? or 2^?.     

Dilepton and strange particles production by neutrinos in gargamelle

New results are presented of an analysis of pictures taken during an exposure of Gargamelle to the CERN ν beam in 1975. In addition to three ν_μ+N→μ^?+e⁺+V⁰+ hadrons events previously reported, an excess is found of events of the type ν_μ+N→μ^?+e⁺+ hadrons without V⁰. An analysis of strange particle production in charged current events suggests a possible violation of the ΔS=ΔQ rule. Interpreted in terms of charm production, the data permit an estimate of branching ratios and production rate of charmed particles. A limit is also placed on charmed particle production by neutral currents.     

Molecular structures in two- and three-centre systems

Some recent studies of clustering in carbon and beryllium isotopes using break-up reaction studies are reported. Studies of the ⁷Li(⁹Be,⁹Be+α) and ⁷Li(⁹Be,¹⁰Be+α) reactions provide an insight into clustering in three-centre systems. Similarly, neutron knockout reactions involving the 4n removal channel with a ¹²Be projectile may provide an insight into the nature of molecular states in two-centre systems.     

Präzisionsmessung des Al27 (n, α)-Wirkungsquerschnitts für 14,43 MeV-Neutronen

A precision measurement of the Al²⁷(n, α) Na²⁴ — cross-section for 14.43 MeV was performed. Aluminium samples were irridiated in an accurately known neutron flux determined by the associated particle method. The induced Na²⁴ activity was measured with a scintillation detector accurately calibrated by means of Na²⁴ standards by the β-γ-coincidence method. By means of careful minimizing all sources of systematic errors an overall accuracy of 0.7% on a 99.5 (3 σ) confidence level was obtained. The measurements result in a cross-section of 117.0 mb for Al²⁷(n, α)Na²⁴ for neutrons of an average energy of 14.43 MeV and an energy width of approximately 0.2 MeV.     

Search for giant spin-flip transitions in 90Zr and 208Pb

We have searched for the giant magnetic dipole resonance in ⁹⁰Zr and an associated state in ²⁰⁸Pb. Among the experimental techniques employed in this search was the detection of inelastically scattered protons in coincidence with ground-state de-excitation γ-rays, No state in ⁹⁰Zr up to an excitation of 10.5 MeV or in ²⁰⁸Pb between 5.0 to 6.0 MeV was observed with the desired characteristics. In ⁹⁰Zr, heretofore unidentified levels at 5.51, 5.89 and 6.42 MeV were determined to have J^π = 1^?. In ²⁰⁸Pb J^π = 1^? states were observed at 5.29, 5.51 and 5.94 MeV. The implications of our observations are discussed.     

Optical gain by upconversion in Tm–Yb oxyfluoride glass ceramic

Evidence of positive optical gain is observed in Tm³⁺–Yb³⁺-codoped oxyfluoride glass ceramic in an upconversion pump and probe experiment. The ¹G₄ level of the Tm³⁺ ions is populated by an upconversion mechanism under excitation of the Yb³⁺ ions at 975 nm with a high-power pulsed laser and give rise to an intense emission from the ¹G₄ to the ³F₄ levels. The ¹G₄→³F₄ electronic transition is stimulated with a low signal at 650 nm as a probe.     

Elastic scattering of deuterons by 14C from Ed = 4 to 10 MeV

Angular distributions for the elastic scattering of deuterons by ¹⁴C were measured at nine energies between E_d = 4.2 and 10 MeV. Excitation functions were taken in 50 keV steps from E_d = 4 to 10 MeV. A resonance was observed at E_d = 4.5 MeV, which corresponds to an excitation energy of 14.41 MeV in ¹⁶N. An analysis using an optical model plus a single-level formula derived from the R-matrix formalism yields an l-value assignment of l = 4 for this resonance. Of the three J^π values allowed for l = 4 (J^π = 3⁺, 4⁺, 5⁺), the value of J_π = 3⁺ is found to be slightly preferred. Possible identification of this resonance with an analog in ¹⁶O is discussed. The angular distributions measured at off-resonance energies were analyzed with an optical-model potential which has a surface-peaked imaginary well. The energy dependence of the real and imaginary well depths are explicitly determined in the present work for E_d = 4 to 10 MeV. The best-fit optical-model parameters obtained from the present study are compared to those from the ¹⁴N(d, d)¹⁴N work.     

Absorption spectra of diatomic molybdenum nitride (MoN), molybdenum oxide (MoO), and molybdenum dimer (Mo2) molecules isolated in Ar,Ne, and Kr matrices

MoN and MoO molecules produced in a hollow cathode discharge have been trapped in Ne, Ar, and Kr matrices at 4.2 and 13 K and investigated by optical spectroscopy. Bands attributed to MoN were identified in the red and blue spectral regions and assigned by comparison with gas phase results to the A⁴π → X⁴Σ^? (a) and B⁴Σ → X⁴Σ^? (a) transitions, respectively. The ground state of Mo¹⁴N has been identified as ⁴Σ^? with ω_e = 1040 cm^?1 in an Ar matrix. Absorptions assigned to MoO in the red spectral region form the (0-0) and (1-0) bands of at least one electronic transition, but could not definitely be correlated with the gas phase results. The ground state vibrational frequency for Mo¹⁶O in an Ar matrix is 893.5 cm^?1. Additionally, Mo₂ absorptions centered at 19 305 cm^?1 were shown to be part of a vibrational progression with an average spacing of 181 cm^?1.     

The breakup of24Mg into16O and8Be

The breakup of²⁴Mg into¹⁶O and⁸Be fragments has been studied using the reactions¹²C(²⁴Mg,¹⁶O⁸Be)¹²C and¹²C(²⁰Ne,¹⁶O⁸Be)⁸Be. In the latter case, discrete states are observed near 24–28 MeV of excitation in²⁴Mg and the yield from this reaction is an order of magnitude greater than that of the former. This implies the excited configuration populated in²⁴Mg is favoured by the transfer of an alpha-particle and would therefore suggest an association with a 4-particle 4-hole configuration. This suggests a link with the octupole stabilised deformed minimum which appears in Nilsson-Strutinsky calculations of the potential energy surface in²⁴Mg, and also with theα —¹⁶O —α structure predicted in cranked cluster model calculations. In the excitation spectrum no states appear above 31 MeV indicating a possible band termination in disagreement with recent results using the¹⁶O+¹²C reaction. These results are discussed in terms of the Harvey model.     

Accretion model for a hot source formation in 72MeV proton induced 3He and 4He emission

Energy spectra and angular distributions of the (p, ^3,4He) reaction on ⁵⁸Ni, ⁹⁰Zr, ²⁰⁹Bi and ²³²Th are analyzed in the framework of an extended, moving-hot-source model. The mass-temperature relation of the hot source is described as the result of an accretion process. The cooling curve and the total emission cross sections are calculated and presented as a function of the emission time.     

Synchronized 13C-15N-NMR Spectroscopy to Follow Kinetics of Glycine Metabolization in the Rat Liver Non-Destructively

A method is proposed for reiterated measurements by turns of ¹³C and ¹⁵N NMR signals at intact rat liver tissue. Eight minutes after Wistar rats had been injected 1,2-¹³C; ¹⁵Nglycine, the liver was excised and stored in the triple resonance probe-head of a 2.1 Tesla NMR spectrometer. Alternatively ¹³C and ¹⁵N spectra were taken over some hours. Continued enzymatic activities of the liver tissue were seen in terms of metabolic changes of each of the carbon and nitrogen groups of glycine. Different half lives were found for the disappearance of the groups. The measurements gave insights into the kinetics and metabolism of an amino acid as an example to follow the vitality of an isolated organ non-destructively.     

Theoretical estimates of the trineutron and tetraneutron binding energies

The trineutron and tetraneutron binding energies are calculated using an interaction which reproduces ³H, ³He, ⁴H, ⁴He, and ⁴Li ground-state properties. A 4?ω model space and completely symmetrized translationally invariant harmonic oscillator eigenstates are used in the analysis. The calculation yields a ³n eigenvalue within the range suggested in an experiment by Ohlsen et al. The ⁴n eigenvalue is consistent with the location of the first T = 2 level in the ⁴He system.     

Static H-2-H-2 Dipole Interactions in a Lyotropic Liquid-Crystal - A 2Dqe Study

The ²H NMR two-dimensional quadrupolar-echo spectra of an α-deuterated surfactant in an aligned hexagonal lyotropic liquid crystal were recorded. Whereas only indications of ²H-¹H and ²H-²H dipole splittings were observed in the F₂ spectra, these residual interactions were displayed in the F₁, spectra as an apparently Lorentzian peak. When gated ¹H decoupling was used, the ²H-²H dipole splittings became visible in the F₁ spectra as three (apparently Lorentzian) peaks. From a fit to the experimental lineshape the frequencies, relative amplitudes, line-widths, and phases of these peaks were determined. The ratio between the ²H-²H dipole and ²H quadrupole splittings was found to be |q| = 0.0041. Since q values of about −0.0040 have been obtained in lamellar phases, these results indicate that the α-methylene angular distribution function with respect to the local surface normal of the cylindrical aggregates may not deviate significantly from threefold symmetry.