Gamma-gamma directional correlations and coincidence studies in154Gd

The intensities, placements andE2/M1 mixing ratios of transitions in the decay of¹⁵⁴Eu have been carefully studied to provide accurate data for microscopic calculations. Coincidence relationships in the decay of¹⁵⁴Eu have been studied extensively with a multiparameterγ-γ coincidence system with two large volume Ge(Li) detectors. Spectra in coincidence with twenty energy gates were analyzed. Twenty-nine new coincidence relationships were established and confirmed most, but not all, of several levels previously assigned by energy fits only. From an analysis of coincidence spectra and singles spectra with a 18% efficiency Ge(Li) detector new information on the gamma-ray intensities were obtained. Precise values of theE2/M1 mixing ratios of transitions from the gamma- and beta-vibrational bands to the g.s. band have been determined fromγ-γ directional correlation measurements with a NaI(Tl)-Ge(Li) detector coincidence system. Mixing ratios were obtained for a number of other transitions including those fromK ^π =0^? and 2⁺ bands from direct and skipped cascade correlations.     

Gamma-gamma directional correlations in the decay of206Po

Directional correlations of gamma-gamma cascades in the decay of²⁰⁶Po have been measured for the first time. Using a multichannel goniometer with 2 Ge(Li) and 6 NaI(Tl) detectors theA ₂ andA ₄ coefficients have been measured for five cascades in²⁰⁶Bi. From the results,E2/M1 mixing ratios of nine transitions are determined. Upper limits of the transition strengths are presented. Three of the measured mixing ratios are compared with theoretical estimates based on magnetic dipole and electric quadrupole moments of neighbouring nuclei.     

Gamma-gamma angular correlations in125Te

Angular correlation measurements of the γ transitions coincident with 35.5 keV in¹²⁵Te were carried out with Ge(Li)-Si(Li) detectors. Mixing ratios for some of the transitions were determined.     

Gamma-gamma angular correlations in105Rh

Gamma-gamma angular correlation measurements have been performed on the cascades 393-263 keV, 413-263 keV, and 316–469 keV emitted in¹⁰⁵Rh after theΒ-decay of¹⁰⁵Ru. From the measured angular correlation coefficients the spins of the states at 469 keV, 785 keV, and 806 keV and the multipolarities of the involved gamma-rays are determined.     

Gamma-gamma directional correlation study in92Zr

The gamma-gamma directional correlation of the 2⁺′-2⁺-0⁺, 913(Iγ=1.69)-934(Iγ =100)keV cascade in⁹²Nb decay has been investigated with a NaI-Ge(Li) system. Our results yieldδ=?0.013 _?0.024 ^+0.041 . This is one of a very few cases where the second 2⁺ to first 2⁺ transition is not predominatelyE2. This may be related to the closed neutron shell, as earlier suggested. [Radioactivity⁹²Zr; measuredγ-γ(θ), deducedδ]     

Gamma-gamma directional correlation measurements in192Os

E2/M1 mixing ratios of transitions in¹⁹²Os have been determined by the gammagamma directional correlation technique. The results are: δ(484.5 keV)= ?10±1, δ(283.3 keV)= ?3.8± 0.7 and δ(201.3 keV)= ?4.6±1.     

Gamma-gamma energy correlations and moment of inertia in light Xe isotopes

High-spin properties of even ^118–122Xe isotopes have been studied in experiments when a 118 MeV ¹²C beam impinged on ¹¹⁴Cd and ¹¹⁶Cd targets. The γ-rays emitted following the reactions were detected by six NaI(Tl) counters. The coincidence events from the counters were sorted into a two-dimensional matrices, from which the energy-correlation spectra were extracted. From the energy correlation spectra the quantities of the collective moment of inertia $\text{I}$⁽²⁾ are deduced and compared with data obtained for the same nuclei in previous experiments, as well as with results from theoretical studies.     

Directional correlation measurements in69Ga

Gamma-gamma directional correlation measurements have been made on the 553.35-318.63, 234.79–871.98 and 1,052.02-871.98 keV cascades in⁶⁹Ga from the decay of⁶⁹Ge using a NaI(Tl)-Ge(Li) coincidence set up. On the basis of these measurements the spin parity of 1/2^?, 3/2^?, 3/2^? and 5/2^? have been assigned respectively to the 318.63, 871.98, 1,106.77 and 1,924.00 keV states in⁶⁹Ga. The results have been discussed and compared with the previous works.     

Gamma-ray-L-x-ray directional correlations in182W

Directional correlations between gamma radiation andL x-rays in¹⁸²W have been measured. The x-rays are emitted following the internal conversion process of the 100.1 keV 2⁺ → 0⁺ transition. The experimental results for anisotropies involving gamma radiation emitted in the 1189.0 keV transition andL x-rays are A(γ?L _l )=?0.073(27),A(γ?L _α)=?0.0102(45),A(γ?L _β)=?0.0031(35), andA(γ?L _γ)=?0.007(13). The value deduced for the coefficientU ₂(e) pertaining to the converted transition isU ₂(e)=0.52(8) in reasonable agreement with the theoretically expected value 0.410. A note is given on the use of internal conversion radial matrix elements.     

Relaxation rates of 69Ga and 71Ga nuclei in aqueous solutions

Line widths in the ⁶Li, ⁷Li, ²³Na, ³⁹K, ⁸⁵Rb, ⁸⁷Rb and ¹³³Cs N.M.R. spectra of solutions of the alkali salts of biphenyl and fluorenone are reported as a function of solvent and temperature. From a numerical analysis of the room temperature data the contribution of the various relaxation mechanisms to the line widths are established. It is shown that the results are consistent with the observed solvent and temperature dependence of the line widths. Values of the electron spin correlation time are obtained and a value of 1·6 ± 0·4 Å is found for the ‘Van der Waals radius’ of the biphenyl anion. Line width expressions for the static and the dynamic ion pair model are presented. It is demonstrated that the static ion pair model applies to solutions of caesium biphenylide. Semi-empirical rules are presented concerning the importance of various relaxation mechanisms for the different alkali nuclei in the type of solution studied here.     

On the directional dependence of Bose-Einstein correlations

A simple method to measure the shape of the particle emission region in high energy particle collisions by interferometry is discussed. Results from an application to data on inelasticpp scattering are compared with results based on determinations of the radial extension of the source. Both show that in the c.m.s., the source is elongated in the beam direction.     

Nonisotropic L-conversion-electron — X-ray directional correlations in160Dy

The directional correlations betweenL-conversion electrons andL x-rays have been measured. The electrons were emitted in the 86.78keV 2⁺→0⁺ transition in¹⁶⁰Dy, in the decay of¹⁶⁰Tb. The experimental results areA ₂₂(e _L -x _Li )=0.085 (22),A ₂₂(e _L -x _Lα )=0.0066 (29),A ₂₂(e _L -x _Lβ )=0.0000 (27), andA ₂₂(e _L -x _Lγ )=0.0096 78). These results are in disagreement with published theoretical values. It is suggested that the discrepancy is due to a phase inconsistency in the internal conversion matrix elements and there is good agreement withA ₂₂ values calculated in this work.     

Gamma-gamma angular correlation studies in97Tc

The rapid rotation of even-even nuclei is investigated. The characteristic properties of Zn, Mo, Sn, Te, Xe, Ba, Ce and Nd isotopes for high spin are presented. Microscopic calculations are based on the modified oscillator average potential including the quadrupole axial (?) and nonaxial (γ) deformations. The potential energy surfaces of the nuclei are obtained by the shell correction method. The nuclear shape determined by the potential energy surface as a function of angular momentum is predicted.     

K, L and M electron directional correlations in Te

Directional correlations of the cascade in ¹²³Te involving K, L and M electrons from the 89 keV M4 transition have been measured in order to determine the δ(E2/M1) value for the 159 keV transition. The result agrees with that from older correlation measurements, but is in conflict with values derived from Coulomb excitation and lifetime measurements as well as from L subshell ratios.     

The hyperfine structure anomalies of67Ga,69Ga,71Ga,72Ga,113In,115In,and117mIn

The ratios of theg _i -factors of⁶⁹Ga and⁷¹Ga and of¹¹³In and¹¹⁵In have been measured by the NMR method. Using hyperfine interaction constants from literature, the hyperfine structure anomalies⁶⁷Δ⁶⁹,⁶⁹Δ⁷¹,⁷¹Δ⁷² of gallium and¹¹³Δ¹¹⁵,¹¹⁵Δ^117m of indium in the² P _1/2 and² P _3/2 atomic ground states have been calculated.     

On-axis energy analysis of69Ga+, Ga2+, and Ga 2 + ions emitted from a gallium liquid metal ion source

On-axis energy distribution measurements of 3 ionic species emitted from a gallium liquid metal ion source are reported. Voltage deficits, FWHM energy spreads, angular intensities and chromatic angular intensities are presented and compared with other published work. Ga⁺ deficit variations with beam current and temperature are discussed in detail. Ga ₂ ⁺ FWHM and deficit changes with source operating conditions are accounted for by a model of droplet fragmentation.     

Conversion-electron-gamma and gamma-gamma directional angular correlations in 160Dy

Gamma-gamma and conversion-electron-gamma angular correlations in ¹⁶⁰Dy have been measured for the 298 keV–966 keV and 298 keV–879 keV cascades. Particle parameters of the 966 keV E2 transition were determined to be b₂(E2; e_K) = +1.23±0.08 and b₂(E2; e_{ΣL + ΣM) = +1.27±0.23}. The multipole mixing ratio for the 298 keV radiation was determined to be δ(M2/E1) = +0.04±0.01 and we have confirmed the value δ(E2/M1) = ?13±2 for the 879 keV. The E0–E2 mixture parameter for the 879 keV transition was determined as q_K = ?0.03±0.09 assuming penetration effects to be negligible.     

Range and range straggling of 15 to 350 keV 69Ga in amorphous silicon

Depth distribution profiles of 15 to 350 keV ⁶⁹Ga+ implanted at room temperature in amorphized silicon have been measured by ⁴He ion Rutherford backscattering. The measured projected ranges and range stragglings are in excellent agreement with the predictions calculated via realistic Monte Carlo simulations, TRIM code.     

From crystalline to glassy gallium fluoride materials: an NMR study of 69Ga and 71Ga quadrupolar nuclei

Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2-ZnF2-GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (nuQ up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum.     

Gamma-gamma angular correlation study of oxygen motion in yttria-stabilized zirconia

The nuclear quadrupole relaxation of ¹⁸¹Ta in ZrO₂9 mole% Y₂O₃ has been measured by time differential angular correlations between 350 and 1150°C. The results are consistent with a distribution of the activation energy controlling the local motion of oxygen vacancies.