Relative internal conversion electron intensities of the 113 keV transition in177Hf

The intensities of the internal conversion lines of the 113 keVM1 +E2 transition in¹⁷⁷Hf have been measured. From comparison with theoretical conversion coefficients the transition has been found to be (95.2 ± 0.5)%E2 corresponding to ¦δ¦=4.5 ± 0.3. The theoreticalL _I andM _I conversion coefficients used in the comparison have been increased by 5% according to the result that for pureE2 transitions in the deformed region theL _I/L _II,L _I/L _III,M _I/M _II, andM _I/M _III theoretical ratios are too low (～5%). Moreover, the present result indicates that theL _II/L _III andM _II/M _III ratios obtained from the tabulations by Hager and Seltzer and from the computer program by Pauli are too high (1–2%).     

High resolution studies of transitions in the decay chain146Gd to146Eu to146Sm

Transitions in¹⁴⁶Eu and¹⁴⁶Sm were studied using a double-focussing beta-ray spectrometer and a Ge(Li) detector. Internal conversion and gamma-ray intensities were determined. The internal conversion spectrum of the three 155, 115 and 116 keV cascading transitions in¹⁴⁶Eu was studied for all subshells.K-,L- andM-subshell ratios were determined andE2/M1 mixing ratios were deduced for these three transitions. Intensities from theN- andO+P-shells were determined and compared to theoretical calculations. All internal conversion intensities were found to be in agreement with theoretical data for pureM1 character with smallE2 admixtures for all the three transitions. Selected parts of the internal conversion spectrum of the transitions in¹⁴⁶Sm were restudied at 0.06% momentum resolution. This study was mainly concentrated on four transition doublets feeding and deexciting the close lying levels at 1,380 and 1,381 keV. A new transition with 702.20 keV energy was detected in the 702–703 keV transition group. Internal conversion coefficients were deduced using reported gamma-ray intensities. Multipole characters of the transitions were deduced and used as a basis for a discussion of the spins and parities of the lower lying excited states of¹⁴⁶Sm.     

Concerning internal conversion coefficients in Hf180

The gamma-ray relative intensities from transitions in Hf¹⁸⁰ following the 5.5 hour Hf^180m decay have been measured using a bent-crystal gamma-ray diffraction monochromator and a least-squares fitting technique. From these measurements it was possible to deduce a value for the internal conversion coefficient for the 93.3-keV transition of α _T ⁹³ =4.91±0.23. From previous measurements of conversion electron intensities byEdwards andBoehm and our gamma-ray relative intensities, internal conversion coefficients for all transitions except the 57.5-keV transition were obtained. These coefficients agree well with the previous determinations byEdwards andBoehm, however, our measurements have improved precision, particularly in the case of 501.3-keV transition. The present measurements of α _K for the 215.3-, 332.5-and 443.8-keVE2 transitions are 11% lower than theoretical values while α_K for 93.3 keV E2 transition agrees closely with the theoretical value. These results are in close agreement with the previous measurements ofEdwards andBoehm. The present experimental α_K for the 501-keV transition agrees closely with the theoretical α_K for an E3 multipolarity.     

The decay of141Ce

The decay of¹⁴¹Ce has been reinvestigated using different experimental methods. The efficiency extrapolation technique applied to 4πβ —γ coincidence measurements has been employed for the determination of the disintegration rate of the sources and of the total internal conversion coefficient. TheK X-ray andγ-ray emisssion rates have been measured with a calibrated Si(Li) and an intrinsic germanium detector. Additionally the photon intensities have been determined from the internal conversion coefficients. Electron experiments with a magneticβ-spectrometer yielded the relative intensities, the shape factors and the maximum energies of the two β^?-transitions and the internal conversion ratiosK/L andK/(L + M+...). TheK-shell internal conversion probability has been determined with an electronK X-ray coincidence technique using the magneticβ-spectrometer together with a high energy resolution Si(Li) detector. New values for the following decay properties have been deduced:β ^?-intensities (p ₁ =0.306 + 0.006,p ₂= 0.694±0.006), shape factorsC = const (1+Aε) (A ₁ = ?(0.24±0.03),A ₂=?(0.22±0.04)), maximumβ ^?-energies (E ₀₁ = (582.2±2.6) keV,E ₀₂= (436.7±4.6) keV),K- shell internal conversion coefficient (α _K = 0.376±0.008), total internal conversion coefficient (α = 0.438±0.010), internal conversion ratios (K/L = 7.29±0.24, K/(L + M + ...) = 5.78±0.18),γ-ray intensity (I _γ = 0.482±0.003),K X-ray intensity (I_{K X} = 0.168±0.002) and the photon intensity ratio (I _{K X} /I _γ = 0.349±0.005). The procedure of uncertainty quotation is presented in some detail. The results are discussed with respect to existing experimental data.     

On the intensities ofK X rays following thermal neutron capture

Through the measurement of the absolute intensities of theK _α andK _β X rays following slow neutron capture in¹⁵⁵Gd,¹⁷⁶Lu and¹⁹⁹Hg and their comparison with the intensities of theK-conversion electron transitions from the same reaction it is shown that theK X rays are caused only by internal conversion.     

Internal conversion coefficients in the Hartree-Fock atomic model. Calculations and experiments for199Hg

The internal conversion coefficients were calculated for the transitions in¹⁹⁹Hg using both Hartree-Fock and Hartree-Fock-Slater atomic models. The relative conversion line intensities were measured with the magnetic spectrometers in Prague and Heidelberg. The multipolarities were determined to be:M1+(0.20±0.03)%E2, pure E2 and M 1+ (13.4 ±0.4)%E2 for the 50, 158 and 208 keV transitions, respectively. Allowing for the nuclear structure effect in M1 component we obtained: M1+(0.15±0.03) %E2,λ = 2.4±1.0 for the 50 keV and M1+ (10.9±0.7)% E2, λ=3.8±0.5 for the 208 keV transitions. Very good agreement was found between theory and experiment for the atomic subshells,K, L_1?3,M _1?5,N, andO + P.     

The conversion electron spectrum in the decay of195Au

Twenty-four internal conversion lines in the decay of¹⁹⁵Au have been studied at high resolution by means of the Vanderbilt iron-free spectrometer. The electron intensities of this work and previously published photon intensities were used to calculate the percentage decay to each level in¹⁹⁵Pt. Conversion coefficients andL subshell ratios were used to assign the following multipolarities: 30.8 keV, pureM1; 98.8 keV, (99±1)%M1; 129.8 keV, pureE2; and 210 keV, pureE2. MeasuredL subshell ratios are not in good agreement with theoretical values.     

L 1 subshell yields atZ=73 from the electron capture decay of181W

The TaL x ray spectrum from the electron capture decay of¹⁸¹W is analyzed into components characteristic of the threeL-subshells and theL ₁ subshell yields atZ=73 are determined to beΩ ₁=0.15±0.02,f ₁₂=0.23±0.05 andf ₁₃=0.32±0.02. A revised decay scheme for the decay of¹⁸¹W is proposed from measurements of x-ray and gamma intensities. A value of 0.97±0.08 for theK-conversion coefficient of the 153 keV transition is obtained and itsE ₂/M ₁ multipolarity mixing ratio,δ ²(0.25) is deduced.     

On the octupole excitation in236U

Measurements of theK,L _I,L _II andM _I conversion lines of the 687.7 keV transition in²³⁶U are evaluated within the electron penetration formalism. The spin-parity assignment of the octupole bandhead is found to be 1^? in accordance with reaction data, and an assignment of 2^? to the 687.7 keV state is ruled out. The penetration matrix element ∥η∥ has the value of 13.5 for theK-shell and increases slightly for higher main shells. An estimate of the anomalous amplitudes is compared with values reported for transitions in the odd even actinide nuclei. Furthermore electron conversion data for the 1^?→2⁺ and 1^?→4⁺ transitions are given. Radioactivity²³⁶U from²³⁵U(n,e ^?); measured: conversion electron decay; deduced: conversion coefficients fromK, L andM shells; evaluated: dynamic matrix elements.     

Experimental determination of penetration parameter forM1 conversion,and theE2 admixtures for 77 and 191 keV transitions in197Au

TheL-subshell conversion for 77 keV transition andK,L ₁,L ₂-shell conversion for 191 keV transition in¹⁹⁷Au, as well asK-shell conversion transition of 158 keV in¹⁹⁹Hg were measured by means of Π√2-iron free electron spectrometer. Relative gamma-ray intensities have been determined by Ge(Li) spectrometer. From these measurements the α _K conversion coefficient value has been deduced for 191 keV transition as α_K(191 keV)=0.86±0.03. This value shows that the spin of the level at 268 keV in¹⁹⁷Au is 3/2⁺. For the penetration parameter (λ) and intensity ratio \(\left( {\delta ^2 = \frac{{\left\langle {E2} \right\rangle ^2 }}{{\left\langle {MI} \right\rangle ^2 }}} \right)\) the following values are obtained: $$\begin{gathered} \lambda = 3.4 \pm _{1.5}^{1.9} \delta ^2 = 0.11 \pm 0.03for 77 keV transition \hfill \\ \lambda = 3.2 \pm _{0.6}^{0.8} \delta ^2 = 0.17 \pm 0.04for 191 keV transition. \hfill \\ \end{gathered} $$ The agreement of these results with the predictions of De Shalit model is discussed.     

Inner-shell ionization by relativistic electron impact

K-, L andM-shell ionization cross sections have been measured for 23 elements, 12≦Z≦92, after bombardment with relativistic electrons, 15≦E ₀65MeV, by means of high resolution semiconductor detectors and a recently developed gas-scintillation proportional counter. For constant electron bombarding energyE ₀ the ionization cross sections follow a power law dependence,σ∽Z ^?α, and forE ₀=50MeV we deducedα =2.45±0.02 for theK shell andα=3.00 ±0.09 for theL shell. The observedZ dependence exhibits significant systematic deviations from theoretical predictions which exceed the experimental values up to 15 % at lowZ elements for theK shell and on the average about 11% for theL andM shell. The same behaviour of too low experimental values, i.e. an overestimation by the theory, is observed for the energy dependence of the cross sections for all shells. A scaling behaviour describing theZ andE ₀ dependence for allK-, L andM-shell data points is observed which also predicts the experimental values by other groups at lower and higher energies correctly. The comparsion of the measuredLΒ/Lα, andLγ/Lα intensity ratios for highZ elements with the values obtained by other groups in the energy range 0.3≦E₀≦1,000 MeV exhibits an increase with bombarding energy that cannot merely be explained by the energy dependence of the subshellionization cross sections for theL shell. An attempt to explain this effect with the change of the Coster-Kronig transition probability is described.     

Energie- und Intensitätsmessungen an Konversionselektronen des Zerfalls75Se→75As

Energies and intensities of conversion lines of elevenγ transitions in the decay⁷⁵Se→⁷⁵As were measured with the Heidelberg (π/2)√13β-ray spectrometer. The experimental transition energies agree with the results of crystal diffraction spectrometer measurements; in some cases more precise values were obtained. The measured relativeK electron intensities for five transitions are in agreement with previous experiments. TheL group of the 97 keV transition was resolved for the first time and the multipolarity was determined to beE2 from theL subshell ratios.     

Decay of194Os andL 1 subshell yields atZ=77

The relative intensities of x rays and gammas emitted in the beta decay of¹⁹⁴Os are measured. No evidence for the feeding of a level at 83 keV in¹⁹⁴Ir is found. An upper limit of 1.7×10^?4 was set for theK shell internal ionization probability in the beta decay to the ground state of¹⁹⁴Ir. TheL-conversion coefficient of 43 keV transition is found to be 12.1 and the transition is mainly ofM1 type with an admixture of 1.3%E2 type. TheL ₁ subshell yields atZ=77 are determined to beω ₁=0.16±0.04,f ₁₂=0.11±0.04 andf ₁₃=0.37±0.03.     

Kern-Isomerie bei In116

The short lived indium isomer produced by thermal neutron capture is confirmed to be In¹¹⁶. A new determination of half-live andγ energy yieldsT _1/2=(2.17α0.07) sec andE _γ=(164±1) keV. From measurement of theK shell conversion coefficient follows that the multipolarity of the transition isE 3, leading to a spin and parity assignment of 8^? for the isomeric level.     

TheK-shell conversion coefficient of the 135.5 keVM4 transition in193m Pt decay

TheK conversion coefficient of the 135.5 keVM4 transition in^193m pt has been determined by the XPG method. The result isα _K =135.2±10.5 and the value exhibits a deviation 3.4% below the theoretical prediction of Hager and Seltzer. Similar deviations have been systematically observed in precision values ofE3 andM4 conversion coefficients reported in the literature.     

The internal conversion of theN=81 Isotones139m Ce and141m Nd

A rapid gas-jet system was used for preparation ofβ ^?-samples of^139m Ce and^141m Nd. Conversion electrons and photons were detected simultaneously with absolutely calibrated detectors. Conversion coefficientsα _K = 0.0732±0.0023 andα _K=0.0824±0.0029, conversion ratiosK/L+...= 4.68±0.20 andK/L+...=4.58±0.23 were measured for^139m Ce, and^141m Nd, respectively. The calculated M4 values of Hager and Seltzer, and Dragoun et al. were confirmed within the experimental accuracy.     

The 693 keV 2+′→2+ transition in154Gd

The multipolarity of the 2²⁺′→2⁺ transition in¹⁵⁴Gd has been investigated. The correlation coefficientA ₂₂=? 0.04±0.10 was determined on an electron — gamma directional correlation spectrometer, while the conversion coefficient α _K =0.046±0.002 was deduced by comparing the normalised electron and gamma intensities. From these values the quantities δ,q _K andX were calculated and compared with the theoretical predictions.     

Spin of207mPo(2.79s); conversion measurement in207gPo decay

In^207m Po decay, the conversion of cascadingγ-rays 268 keV, 300 keV, and 814 keV was measured yielding the multipolarity to beE3.M2, andE2, respectively. Thereby, the spin of the isomeric state at 1382.95±0.14 keV was measured to be 19/2^?. In^207g Po decay, conversion electron andγ-ray intensities were remeasured in order to check earlier experimental inconsistencies.     

Reinvestigation of the decay scheme of the short-lived isomeric states in112In

The two short-lived isomeric states in¹¹²In have been reinvestigated by means of the¹¹²Cd(d, 2n) and¹⁰⁹Ag (α, n) reactions. Measurements of delayed X- andγ-ray, lifetime and TDPAD spectra have been performed. A 6.32(3) keVγ-ray has been identified in the isomeric decay and anM1 multipolarity has been assigned to it on the basis of the measured internal conversion coefficients:α _L =196(39) andα _tot=231(35). TheE1+M2(δ =+0.24(4)) andE2 multipolarities have been determined for the 263 and 188 keV transitions deexciting the 8^?(T _1/2=2.82(2) μs) and 7⁺ (T _1/2=0.93(2) μs) isomeric states, respectively. A revised isomeric decay scheme is presented.     

L-subshell fluorescence and coster-kronig yields atZ=92 and the decay of235Np

TheK andL x-rays emitted in the decay of²³⁵Np have been studied with high resolution Ge(HP) and Si(Li) detectors in coincidence, in order to obtain theL ₂ andL ₃ subshell fluorescence and Coster-Kronig yields atZ=92. The results are:v ₂=0.630±0.036, ω₂=0.560±0.033,f ₂₃=0.147±0.010, and ω₃=0.481±0.029. Results for theL ₁ subshell were derived from singles spectra, by assuming a value off ₁₃ of 0.67, and are:v ₁=0.54±0.04, ω₁=0.21±0.04, andf ₁₂<0.07. With the same assumption, theL ₁/K electron capture ratio and decay energyQ _ec for²³⁵Np were found to be 29.0±3.6 and 123.6±0.7 keV, respectively. RelativeL x-ray intensities forZ=92 also were measured and are compared with the theory of Scofield and with recent diffraction experiments. Electron ejection from theL shell during²³⁵Np decay has been studied byL x-ray-L x-ray coincidences and found to occur with a probability of (1.3±1.0) × 10^?4 per disintegration.