Spectroscopic study of 55Co via the 54Fe(τ, d)55Co and 54Fe(τ, dp̃)54Fe reactions

The ⁵⁴Fe(τ, d)⁵⁵Co reaction has been studied at 25 MeV incident energy with a split-pole spectrometer. About one hundred levels have been observed in ⁵⁵Co up to 10 MeV excitation energy. Angular distributions have been measured and analyzed with DWBA and Gamow functions as form factors for unbound levels. The ⁵⁴Fe(τ,dp?)⁵⁴ reaction has been investigated at 24 MeV incident energy. The angular distributions of the emitted protons were measured in coincidence using method 2 of Litherland and Ferguson, with 0 detection of deuteron groups. Spins, population parameters, branching ratios and proton partial widths for the transitions to the ground and excited states of ⁵⁴Fe were determined from the analysis of the angular correlation data. The results of these two experiments provide a large number ofspectroscopic properties of unbound proton states and in particular of analog states of ⁵⁵Fe low-lying levels. The IAS of the $\text{3}\text{2}{}^{\mathrm{?}}$ ground state of ⁵⁵Fe is observed to be split between two individual levels. The amplitude of neutron coupling to the first 2⁺ excited state of ⁵⁴Fe is obtained for the $\text{lg}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ and $\text{2}\text{d}\text{5}\text{2}$ low-lying parent statfes in ⁵⁵Fe. summed spectroscopic factors and the centroid energies of the proton states in ⁵⁵Co are obtained. A comparison is made with previous (τ, d), (d, p) and (p, p) results.     

The YN interactions and K− reactions on deuterium at low energies

The K^?d → π^?Λp reaction, as well as the other three-body K^? reactions on deuterium, are considered for s-wave kaons in the Faddeev formalism for charge-independent separable two-body coupled-channel interactions fitted to the available low-energy data. In particular we study the effect of a hypothetical $\text{I =}\text{1}\text{2}\text{, S = 1, Σ}\text{N}$ unstable bound state near the πΣN threshold on the shape of the calculated Λp invariant mass distribution near the ΣN threshold. This calculated distribution always exhibits a cusp behavior at the ΣN threshold, but considerable structure and broadening may be reached by varying the parameters of the YN interaction. Multiple scatterings in the initial K?NN and intermediate πΣN channels play a dominant role at low energy. The calculation compares favorably with the measurements at rest and at low energies. This comparison suggests that a ΣN bound state does not exist near the ΣN threshold.     

Direct transfer and two-step processes in the 42Ca(α, 3He)43Ca reaction

The ⁴²Ca(α, ³He)⁴³Ca reaction has been studied at 36 MeV incident energy. Angular distributions have been measured from 4° to 42° using a split-pole spectrometer and position sensitive Si detectors, for about 40 levels located up to 6 MeV excitation energy. A local zero-range DWBA analysis has been carried out; l = 3 and 4 assignments are tentatively proposed for levels located above 4 MeV excitation energy, indicating a strong fragmentation of the $\text{1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ strength between 4 and 6 MeV and the location of the main component of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ strength above 6 MeV. A number of weakly excited levels cannot be reproduced by DWBA analysis. Their angular distributions have been compared with the results of coupled-reaction-channel calculations assuming two-step excitation of weak coupling states with a [⁴²Ca¹ ? $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ structure. A reasonable agreement has been obtained, confirming that the two-step process cannot be neglected in the analysis of the (α, ³he) reaction.     

Neutron-hole strengths and isobaric analog states in 95Zr

The ⁹⁶Zr(τ, α)⁹⁵Zr reaction at 39 MeV incident energy was used to populate both the low-lying and highly excited (up to an excitation energy of 18 MeV) analog states in ⁹⁵Zr and some low-lying levels in other Zr isotopes. The main components of the 2d_{$\text{5}\text{2}$}. and 1g_{$\text{9}\text{2}$}. hole strengths and the analogs of the 2p_{$\text{1}\text{2}$}., 2p_{$\text{3}\text{2}$}. and 1f_{$\text{3}\text{2}$}. proton hole states in ⁹⁵Y have been observed in this work. Angular distributions of transitions to 27 levels in ⁹⁵Zr have been extracted and analysed with DWBA calculations to yield spectroscopic factors. Between the excitation energies of 1 and 3 MeV in ⁹⁵Zr a number of levels with l = 2, 4 and 5 angular distributions have been identified. These are associated with the 2d_{$\text{3}\text{2}$}, 1g_{$\text{7}\text{2}$} and 1h_{$\text{11}\text{2}$} components already observed in the previous study of the ⁹⁴Zr(d, p) and (α, τ) reactions. The total strength and center of gravity for levels assigned to the (1g_{$\text{9}\text{2}$})^?1 configurations in ⁹⁵Zr are presented and compared to the results obtained from the studies of neutron pick-up reaction on ⁹¹Zr and ⁹⁸Mo. For the isobaric analog states observed between the excitation energies of 15 and 17 MeV, total widths, Coulomb displacement energies and spectroscopic factors are also determined from this experiment and the results compared with the properties of the low-lying proton hole states in the ⁹⁵Y parent nucleus.     

Électrochimie dans l'oxydipropionitrile: Comportement électrochimique du solvant. Stabilité des complexes argent(I) halogénures. Solvatation des anions

Electrochemical possibilities of oxydipropionitrile have been shown. The system Ag(s)/Ag⁺ has been used to make a reference electrode in this medium. The electroactivity range which depends on the electrolyte and the kind of electrode used has been specified. At a platinum electrode, in LiClO₄ medium, the electroactivity range is very large. At a mercury electrode, water does not interfere but at a platinum electrode it is oxidizable; the electroactivity range depends on its concentration. The second part treats the complexes with silver ion and halides. Stability constants of complexes and solubility products have been obtained from potentiometric titration curves. The determination of the transfer parameters for ionic species is based on the Strehlow assumption that the potential of the ferrocene/ferricinium couple is constant in all solvents. The results show that the silver ion is more strongly solvated in oxydipropionitrile than in water; on the other hand halide ions are little solvated in this solvent.     

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Spectrophotometric extractive titrations-II Determination in gallium arsenide of the sum of metals extractable with dithizone

A procedure for the determination of the sum of metals, which are extractable with dithizone, in gallium arsenide is given. After the dissolution of the sample the impurities are extracted with several portions of 10(-4)M dithizone in carbon tetrachloride, gallium being screened by tartrate ion. The excess of the reagent is extracted into 0.1M aqueous ammonia and after stripping into carbon tetrachloride the dithizone is determined by spectrophotometric extractive titration. The effect of pH is considered. The limit of detection, based on the evaluation of twenty blanks, is 2.30 x 10(-8) mole, the equivalent of 1.50 mug of zinc.     

Mossbauer studies of Np hydrides

The Mossbauer spectra of ²³⁷Np in NpH_2+x(x = 0.1, 0.3 and 0.5) consist of several absorption lines which are attributed to Np inequivalent sites corresponding to different numbers of octahedral hydrogen neighbours. The relative intensities of the various lines do not correspond to a random distribution of the hydrogen ions. A model which takes into account first nearest neighbour interactions among octahedral hydrogen ions can reproduce the experimental spectra.