Hole-vibration states in 115In

The hole-vibration coupling in the Z = 50 region is investigated by calculating the level structure of ¹¹⁵In. Four proton-hole states are coupled with quadrupole and octupole core vibrations. The phonon energies and the amplitudes of the vibrational motions are taken from experiment, while the single-hole energies are treated as free parameters. Most of the observed features of a quintet of states with $\text{I}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{+}}\text{,}\text{7}\text{2}{}^{\mathrm{+}}\text{,}\text{9}\text{2}{}^{\mathrm{+}}\text{,}\text{11}\text{2}{}^{\mathrm{+}}\text{,}\text{13}\text{2}{}^{\mathrm{+}}$, which have enhanced E2 transition strengths to the ground state, are well reproduced by the theory. The hole-vibration coupling produces a strong fragmentation of the single-hole strengths. This is quite in agreement with the results of (d, ³He) experiments on ¹¹⁶Sn.     

Fluorescence nucléaire de 115In

Continuous radiation (bremsstrahlung) from a 2 MeV electron accelerator has been used to excite seven nuclear levels in ¹¹⁵In, at 1133, 1291, 1449, 1464, 1487, 1498 and 1610 keV. Mean-life values were calculated for the first five levels and the δ² ratio was also determined for those at 1133 and 1464 keV.     

NMR of 69Ga, 71Ga,and 51V in V3−xFex Ga alloys

We have studied at room temperature the intensities and the Knight shifts of the nuclear magnetic resonances of ⁶⁹Ga, ⁷¹Ga, and ⁵¹V in V_3?xFe_xGa for Fe concentrations ranging from x = 0.04 to x = 0.6. The results interpreted in terms of a redistribution of the conduction electrons and a paramagnetism due to the Fe impurities.     

Excited states in 69Ge observed in the 69Ga(p,nγ) reaction

Energy levels of ⁶⁹Ge are populated by the ⁶⁹Ga(p, n) reaction. Angular distributions and DSAM are used to extract information on spins and γ-decay properties of the levels of this nucleus. The observed structure of the negative- and positive-parity states is compared with the predictions of the one- and three-particle-cluster—core coupling model.     

Gamma rays from resonance neutron capture in 115In

Gamma rays in the range 5.4–6.7 MeV have been studied for 31 s-wave neutron resonances of ¹¹⁵In, selected by time of flight in the range 3–430 eV. In a subsidiary experiment, spin J = 5 has been assigned to 17 and J = 4 to 14 resonances by measuring intensity variations of some strong low-energy transitions. The reduced widths averaged over all initial states of the same spin have been estimated for 41 primary transitions: these values have provided information on the spin and parity of the corresponding ¹¹⁶In final states. Overall mean values of E1 and M1 radiative strength have been calculated. The width distribution has been fitted with a χ² function with ν = 1.10^+0.27_?0.09 degrees of freedom for M1 and ν = 1.42 ^{+ 0.014}_?0.08 for E1 radiation. An estimate of the spin cut-off parameter σ = 3.6_?0.4^{+ 0.8} has been derived. A non-statistical effect already evidenced in previous measurements has been confirmed, consisting of a strong modulation of the radiative strength against resonance energy, correlated also with the local neutron strength function. In addition, it has now been shown that this structure is due to E1 radiation only.     

(γ, γ′) reactions in 89Y, 115In and 197Au at intermediate energies

The yields of isomeric states in ⁸⁹Y, ¹¹⁵In and ¹⁹⁷Au produced by the (γ, γ') reaction have been measured in the energy range 100–800 MeV by the activation method. From the yields the cross sections have been deduced. Large cross sections around the first pion resonance are found. The experimental results are compared to calculations based on the impulse approximation.     

Angular distributions for target residues in reactions of 14N and 12C with 115In

Mechanisms of the reactions of ¹²C and ¹⁴N with ¹¹⁵In have been investigated by measuring the angular distributions of the target residues. Various possible transfer mechanisms are discussed with the help of kinematic analysis and a semiclassical transfer model. Interesting secondary (or tertiary) peaks are seen near 90 in the angular distributions for most target residues.     

Proton-hole states in 115In observed in the 116Sn(d, 3He) reaction

The ¹¹⁶Sn(d, ³He)¹¹⁵In reaction has been investigated at E_d = 50 MeV. Thirteen transitions to states up to 3 MeV excitation energy were studied. The measured angular distributions were compared with DWBA calculations and transferred angular momenta and spectroscopic factors were deduced. Levels at 1.04, 2.23 and 2.52 MeV were found to be excited most likely by l = 3 angular momentum transfer in contrast to previous investigations at lower incident energies in which no l = 3 transitions have been observed.     

Differential cross sections for radiative capture of energetic protons by 110Cd and 115In

Spectra of high-energy photons following the radiative capture of 8–22 MeV protons in ¹¹⁰Cd and ¹¹¹In are measured. The (p, γ) differential cross sections at 90° with respect to the beam axis is deduced from the integration of measured spectra. The photon angular distribution is measured for the ${}^{110}\text{Cd}\text{(}\text{p}\text{, γ}{}_0\text{)}$ reaction, too, at 13 MeV incident energy. Satisfactory agreement between theory and experiment is obtained by using the direct-semidirect model for dipole and quadrupole fast nucleon radiative capture.     

The magnetic moment of the 828 keV level in 115In

The magnetic moment of the 828 keV level in ¹¹⁵In was found to be 0.80 ± 0.14 μ_N by measuring the γ-γ integral angular correlation perturbed by an external magnetic field. Several assumptions concerning the nature of the state investigated have been discussed.     

Cross sections for 197Au(n, γ)198Au and 115In(n, γ)116mIn in the neutron energy region 2.0–7.7 MeV

The cross sections for the reactions ¹⁹⁷Au(n, γ)¹⁹⁸Au and ¹¹⁵In(n, γ)^116mIn have been measured with the activation method in the neutron energy region 2.0–7.7 MeV. The influence of background neutrons on the results was studied in considerable detail. The main problems are caused by low-energy neutrons produced by charged-particle reactions in the target material and secondary neutrons from nonelastic reactions in the sample and surrounding materials.The measured capture cross sections are generally lower than previous results and the deviation tends to increase with increasing neutron energy. The data are also compared with calculations based on the compound-nucleus model and quite good agreement is obtained.     

A study of isobaric analogue resonances in 71Ga

Differential cross-section and analysing-power excitation functions were measured for elastic proton scattering from E_p = 3.6–6.4 MeV at θ_c.m. = 90°, 115.8°, 129.8° and 155.3°. Differential cross-section angular distributions were measured at 3.56, 3.94, 5.78 and 8.98 MeV and analysing-power angular distributions at 5.78 and 8.98 MeV. Optical-model parameters were deduced from these distributions. Resonance parameters were determined for eight analogue resonances in ⁷¹Ga and neutron spectroscopic factors were calculated. These were compared with the results of previous (p, p) cross-section analyses and the results of (d, p) reactions leading to states in ⁷¹Zn.     

The nature of negative linear expansion in layer crystals C,Bn, GaS,GaSe and InSe

Experimental investigations of thermal expansion parallel and perpendicular to the layers plane of layer crystals GaS, GaSe and InSe are described. The obtained results are analized together with known thermal expansion data on graphite, C, and boron nitride, BN. Theoretical calculations of linear expansion coefficients are carried out on the basis of the model of highly anisotropic crystal. It is shown, that the negative thermal expansion in the layer plane, typical of layer crystals, is due to “bending” waves, acoustic waves propagating in the layer plane and polarized perpendicular to this plane (TA_⊥ mode)     

A perturbed angular distribution in 70Ga

A pulsed proton beam and coaxial Ge(Li) detector were used to study the time dependence of the angular distribution of γ-rays resulting from the decay of the 879 keV state in ⁷⁰Ga, as excited by the ⁷⁰Zn(p, n)⁷⁰Ga reaction. A strong time-dependent attenuation of anisotropy was observed. The unperturbed value of the angular distribution is consistent with the assignment of spin I = 4 to the 879 keV level. The half-life of the 879 keV state was measured to be $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 22.7 ± 0.5}\text{ns}$.     

Calculation of capture rates of solar and galactic neutrinos by69Ga and71Ga

Summary Calculations of the neutrino-capture cross sections for^69,71Ga based on a microscopic treatment of the Gamow-Teller matrix elements are presented. A strong enhancement of the cross-section for high-energetic neutrinos is found compared to previous phenomenological estimates. As a consequence the present assumptions on the signal from⁸B neutrinos in⁷¹Ga have to be revised. A rather large solar model dependent background of⁸B neutrinos has to be expected in a gallium solarneutrino experiment together with the pp signal. This will complicate the interpretation of such an experiment particularly in the case of neutrino oscillations with not maximum mixing angle. The calculations yield a larger sensitivity of the gallium detector than assumed previously for galactic neutrinos.

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Riassunto Si presentano i calcoli delle sezioni d'urto di cattura neutrinica per^69,71Ga basati su un trattamento microscopico degli elementi di matrice di Gamow-Teller. Si trova un forte aumento della sezione d'urto rispetto a stime fenomenologiche precedenti. Di conseguenza gli assunti attuali sul segnale dai neutrini⁸B in⁷¹Ga devono essere riveduti. Si prevede un sottofondo abbastanza grande, dipendente dal modello solare di neutrini di⁸B in un esperimento di neutrini solari di⁷¹Ga con il segnale pp. Ciò complicherà l'interpretazione di questo esperimento particolarmente nel caso di oscillazioni neutriniche con angolo di mescolamento non massimo. I calcoli danno una sensibilità maggiore del rivelatore di gallio rispetto a quanto precedentemente assunto per i neutrini galattici.

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Резюме Проводятся вычисления поперечных сечений захвата нейтрино в^69,71Ga на основе микроскопического рассмотрения матричных элементов Гамова-Теллера. Обнаружено сильное увеличение поперечного сечения для нейтрино высоких энергий по сравнению с предыдущими феноменологическими оценками. В рамках предложенного подхода заново определяется сигнал от⁸B-нейтрино в⁷¹Ga. Отмечается наличие довольно большого фона нейтрино. Это приводит к проблемам при интерпретации эксперимента с солнечными нейтрино в галлии в случае нейтринных осцилляций с немаксимальным углом смешивания. Вычисления приводят к большей чувствительности галлиевого детектора, чем предполагалось ранее для галактических нейтрино.

     

High-spin states in 107Sn and 107In isotopes

The isotopes ¹⁰⁷Sn and ¹⁰⁷In were produced through the ¹⁰⁶Cd(³He, 2n)¹⁰⁷Sn and ¹⁰⁶Cd(³He, pn)¹⁰⁷In reactions. They were studied by means of γ-spectroscopy, excitation functions, γγ coincidences and angular distributions of γ-rays. A level scheme is proposed for the newly discovered ¹⁰⁷Sn, and new states belonging to ¹⁰⁷In are given. Microscopic calculations have been performed in a three-quasiparticle approximation for a large number of tin isotopes in order to get a wide view of the systematic evolution of the various states.     

Origin of the high-and low-frequency K-satellites of 31Ga, 32Ge and 33As

The origin of the high- and low-frequency K-satellites of ³¹Ga, ³²Ge, ³³ As is explain on the basis of Hayasi's theory of quasi-stationary states. It is shown that the same QSS difference gives rise to a particular satellite of either type in all the elements. The results are compared with those of multiple ionisation theory.     

Isospin impurity of 64Ga ground state

It is well known that the observation of a nonzero Fermi matrix element for a β-transition between states that differ in isospin can provide information about the relative isospin purity of the states involved. We have determined the log ft value for the 0⁺ → 0⁺ (ΔT ≠ 0) β-transition in ${}^{64}\text{Ga}\text{→}{}^{64}\text{Zn}$ decay as 6.516 ± 0.020. From this log ft value, we have deduced |M_F| = (43.4 ± 1.1) × 10^?3, |α| = (21.7 ± 0.6) × 10^?3 and |〈V_CD〉| = 41.7 ± 1.1 keV, where M_F,α² and 〈V_CD〉 represent the Fermi matrix element, isospin impurity and Coulomb matrix element, respectively. The Coulomb matrix element of 41.7 keV found for ⁶⁴Ga is one of the largest known from β-decay experiments. The experimental procedure involved a careful measurement of the intensity of the annihilation radiation relative to that of the other γ-rays from ⁶⁴Ga decay. As a by-product, we have obtained an improved ⁶⁴Ga decay scheme. We have also summarized the existing information on the isospin impurities of nuclear states as deduced from β-decay experiments.