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The 30.8 keV ${(1/2)}^{\ensuremath{-}}$ isomeric state in $_{41}^{93}\mathrm{Nb}$ decays by an $M4$ transition to the ${(9/2)}^{+}$ ground state. We have measured the $K$-shell internal conversion coefficient ${\ensuremath{\alpha}}_{K}$ for this transition in order to test the validity of current methods of calculation for a case with relatively low atomic number, low transition energy, and a high value of ${\ensuremath{\alpha}}_{K}$. Taking the fluorescence yield of niobium to be 0.751(4), we obtain ${\ensuremath{\alpha}}_{K}=2.56(9)\ifmmode\times\else\texttimes\fi{}{10}^{4}$, a result that agrees with the Dirac-Fock calculations that take into account the presence of a $K$ vacancy in the final state, and disagrees by 1.7 standard deviations with calculations that ignore the vacancy. We also determine the energy of the isomeric state to be 30.760(5) keV, a fourfold improvement in precision over the currently accepted value.

The E0 transition strength in the 2 2 + → 2 1 + transitions of 58,60,62Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ ( E 2 / M 1 ) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ ( E 2 / M 1 ) mixing ratios and γ-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E0 strengths. These are the first 2 + → 2 + E0 transition strengths measured in nuclei with spherical ground states and the E0 component is found to be unexpectedly large; in fact, these are amongst the largest E0 transition strengths in medium and heavy nuclei reported to date.

The L subshell internal conversion coefficient ratios LI/Lir/LIII were determined for the 112.0 kev transition from Lul77 and the 85.1 kev transition from Tbl60 and were found to be

We have measured the $K$-shell internal conversion coefficient, ${\ensuremath{\alpha}}_{K}$, for the 88.2-keV $M4$ transition from the 106-day isomer to the ground state in $^{127}\mathrm{Te}$ to be 484(6). When compared with Dirac-Fock calculations of ${\ensuremath{\alpha}}_{K}$, this result agrees well with the version of the theory that incorporates the effect of the $K$-shell atomic vacancy and disagrees with the one that does not. As a byproduct of this measurement, we have determined the $\ensuremath{\beta}$ branching from the isomer to be 2.14(3)%.

A windowless Peltier-cooled silicon drift detector (SDD) was used to measure internal conversion electron (ICE) spectra of thin 241Am sources. The ICE peaks associated with the 59.54 keV gamma transition in 237Np were deconvoluted and relative ICE intensities were derived from the fitted peak areas. Corrections were made for energy dependence of the full-energy-peak counting efficiency, based on Monte Carlo simulations. As expected for this anomalous E1 transition, a significant discrepancy was found with the theoretical internal conversion coefficient (ICC) values calculated from the BrIcc database. Penetration effects are known to cause such anomalies in highly retarded transitions. The measured ICE intensities are in good agreement with a specific combination of literature data obtained with magnetic spectrometers.

In this article, the cross section of different fusion reactions is determined: D(d,p)T, D(d,γ) 4 He,T(d,n) 4 He and D(p,γ) 3 He by considering the lattice effect in internal conversion of solid state in palladium environment which is a face-cubic-centered-structured metal. Fusionable particles are solved as sublattice; these particles contribute in fusion reaction in palladium environment. Fusion reaction is generated by flux of incoming fusionable particles. In order to enter the lattice effect in the fusion cross section for above reactions, It need to use The Bloch function for the initial and final state of threebody system. The Original Research Article Physical Science International Journal, 4(10): 1383-1399, 2014 1384 three body system consists of the host lattice, sublattice and incident particles. Then the new fusion cross sections are compared with ordinary ones. Finally, the internal conversion coefficient is obtained with regarding the lattice effect. The authors strongly discuss that the lattice effect in solid state internal conversion must be considered until the experimental data of fusion cross section have a good justification with theoretical hypothesis.

The heavy actinide nucleus 253No (Z = 102) was studied using the (S)ilicon (A)nd (Ge)rmanium (SAGE) spectrometer allowing simultaneous in-beam $\gamma$ -ray and conversion electron spectroscopy at the accelerator laboratory of the University of Jyvaskyla. Using the recoil-tagging technique, $\gamma$ -electron coincidences have allowed for the extension of the level scheme in the lower-spin region of the yrast band. In addition, internal conversion coefficient (ICC) measurements to establish the multipolarity of transitions have been performed. Measurement of the interband-intraband branching ratios supports the assignment of the Nilsson band-head configuration $9/2^{-}[734]$ assigned in previous studies. The study shows the viability of combined in-beam electron and $\gamma$ -ray spectroscopy down to μb cross sections.

The first excited isomeric state of Th-229 possesses the lowest energy among all known excited nuclear states. The expected energy is accessible with today's laser technology and in principle allows for a direct optical laser excitation of the nucleus. The isomer decays via three channels to its ground state (internal conversion, gamma decay, and bound internal conversion), whose strengths depend on the charge state of Th-229m. We report on the measurement of the internal-conversion decay half-life of neutral (229)mTh. A half-life of 7 +/- 1 mu s has been measured, which is in the range of theoretical predictions and, based on the theoretically expected lifetime of approximate to 10(4) s of the photonic decay channel, gives further support for an internal conversion coefficient of approximate to 10(9), thus constraining the strength of a radiative branch in the presence of internal conversion.

The 2002 version of Nuclear Data Sheets for A = 198 (2002Zh04) has been updated and revised on the basis of the experimental results from various decay and reaction studies before June 2008. The experimental data for all known nuclei of A = 198 (Ir,Pt,Au,Hg, Tl,Pb,Bi,Po,At,Rn) have been reevaluated. The experimental methods, references, Jπ arguments, and necessary comments are given in the text. The theoretical internal conversion coefficient (ICC) (and its associated uncertainty) for γ-rays have been interpolated from theoretical values based on the “Frozen Orbital” approximation (2002Ba85) using the BRICC(v2.2) computer program. Summary band-structure drawings and level schemes from both radioactive decay and reaction studies are presented. Also of special interest are the new levels of 198 Ir, 198 Tl nuclei and identification of new superdeformed bands in 198 Pb and 198 Po.

The high-spin level schemes of odd–odd 100Nb ( Z = 41 , N = 59 ) and 148La ( Z = 57 , N = 91 ) were identified from γ – γ – γ coincidence studies of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity assignments for the levels in these two nuclei were made based on the low-lying levels assigned in decay work, on the internal conversion coefficient (ICC) measurements and the level systematics of the neighboring isotopes. A K π = 1 + deformed ground-state band was identified in 100Nb. The onset of ground-state deformation in Nb isotopes is found to take place at N = 59 , in contrast to N = 60 for Sr ( Z = 38 ), Y ( Z = 39 ) and Zr ( Z = 40 ) isotopes. Unlike the observation in 99Nb, the N = 56 subshell closure seems to be no longer dominant in 100Nb. The bands observed in 148La are interpreted as aligned coupling of [ π h 11 / 2 υ h 9 / 2 ] low J to the deformed core rotor.

A new internal conversion coefficient database, BrIcc has been developed which integrates a number of tabulations on internal conversion electron (ICC) and electron–positron pair conversion coefficients (IPC), as well as Ω ( E 0 ) electronic factors. A critical review of general formulae and procedures to evaluate theoretical ICC and IPC values are presented, including the treatment of uncertainties in transition energy and mixing ratio in accordance with the Evaluated Nuclear Structure Data File. The default ICC table, based on the Dirac–Fock calculations using the so called “Frozen Orbital” approximation, takes into account the effect of atomic vacancies created in the conversion process. The table has been calculated for all atomic shells and to cover transition energies of 1–6000 keV and atomic numbers of Z = 5 –110. The software tools presented here are well suited for basic nuclear structure research and for a range of applications.

Decay properties of neutron-deficient exotic nuclei close to A=80 have been investigated at the IGISOL facility. The studied nuclei, 81Y, 81Sr, 81mKr, 85Nb, 85Zr, 86Mo and 86Nb, were produced by a 32S beam from the Jyvaskyla isochronous cyclotron on 54Fe and natNi targets. The internal conversion coefficient for a 190.5 keV isomeric transition in 81mKr has been measured and the internal transition rate has been determined. The internal transition rate has been used to estimate a neutrino capture rate on 81Br, which yields a log ft of 5.13±0.09 for the reaction 81Br( ν, e-)81mKr. A new isomer with a half-life of 3.3±0.9 s has been observed in 85Nb. The existence of an earlier reported isomer with a half-life of 56 s in 86Nb has not been confirmed.

The γ- and conversion electron spectra following131Ba e-decay are investigated, using HPGe detector and mini-orange electron spectrometer. Attention is particularly focussed on identifying weak transitions associated with low energy high spin levels in131Cs level scheme earlier inferred in reaction studies but not yet observed in131Ba decay. Our experiment identifies 15 new gammas and 6 new conversion lines in this decay. Internal conversion coefficients and multipolarities of several transitions are determined. Five new levels (3 with Iπ = 7/2+ and one each with Iπ 9/2+ and 11/2−) are introduced in the131Cs level scheme based on our observations taken together with the results from reaction studies. Spin-parity assignments to a few other levels are also suggested

(i) The deformation of the nuclear ground state is a fundamental property that can be deduced in even-even nuclei from the B(E2) value for the first 2+ (21+) state. In 1987, we published a compilation of such B(E2: 01+→ 21+) values for ~ 280 even-even nuclei. Very recently, we have updated the 1987 compilation and have compared the adopted B(E2: 01+ → 21+) values (for ~ 330 even-even nuclei) with those given by various theoretical models (Finite-Range Droplet Model, Woods Saxon Model, Relativistic Mean-Field Calculations, Extended Thomas-Fermi Strutinski Integral Method, Hartree-Fock+BCS Calculations, and Dynamical Microscopic Model). Agreement between theory and experiment varies from “reasonable” to “excellent”.(ii) Currently, the most widely used Internal Conversion Coefficient (ICC) compilations are those by Hager and Seltzer, Rosel et al., and Band and Trzhaskovskaya. In all three cases, the calculation of electron wave functions is carried out in the framework of the Hartree-Fock-Slater (HFS) method...

The complex of problems associated with the discrete conversion of gamma rays is considered. The analogue of the internal conversion coefficient is determined for the case of discrete conversion, and specific computations are made. The calculated values of the half-life of the nuclear level Eγ = 35.492 keV in 125TeQ ions (Q = 45–48) are in good agreement with the measured quantities. Computations for the spectrum of optical photons accompanying the de-excitation of the nuclear level Eγ = 3.5 ± 1 eV in 229Th, carried out using the Dirac-Fock multiple configuration method, show that the highest-intensity spectral lines are situated in the region of 2.3–2.4 eV, which is in accord with the experimental data.

There is a significant discrepancy in the reported values for the emission probability of the 186 keV gamma-ray resulting from the alpha decay of 226 Ra to 186 keV excited state of 222 Rn. Published values fall in the range of 3.28 to 3.59 gamma-rays per 100 alpha-decays. An interesting observation is that the lower value, 3.28, is based on measuring the 186 keV gamma-ray intensity relative to the 226 Ra alpha-branch to the 186 keV level. The higher values, which are close to 3.59, are based on measuring the gamma-ray intensity from mass standards of 226 Ra that are traceable to the mass standards prepared by HONIGSCHMID in the early 1930's. This discrepancy was resolved in this work by carefully measuring the 226 Ra alpha-branch intensities, then applying the theoretical E2 multipolarity internal conversion coefficient of 0.692±0.007 to calculate the 186 keV gamma-ray emission probability. The measured value for the alpha branch to the 186 keV excited state was (6.16±0.03)%, which gives a 186 keV gamma-ray emission probability of (3.64±0.04)%. This value is in excellent agreement with the most recently reported 186 keV gamma-ray emission probabilities determined using 226 Ra mass standards.

We have studied the ionic charge state dependence of the nuclear lifetime of the 35.5-keV first excited state of {sup 125}Te. We found for the 47{sup +} and 48{sup +} ions, 400 and 670{percent} variations with respect to the neutral-atom half-life (1.49 ns). These unusually large effects are due to the energetic blocking of the K-shell internal conversion as the charge state increases past 47{sup +}. For the 46{sup +}, we suggest a new internal conversion mode without any electron emission into the energy continuum. {copyright} {ital 1997} {ital The American Physical Society}

The standardization of (111)In by means of a 4πβ-γ coincidence system, composed of a proportional counter in 4π geometry, coupled to a 20% relative efficiency HPGe crystal, for measuring gamma-rays is presented. The data acquisition was performed by means of the software coincidence system (SCS) and the activity was determined by the extrapolation technique. Two gamma-ray windows were selected: at 171 keV and 245 keV total absorption peaks, allowing the determination of the total internal conversion coefficient for these two gamma transitions. The results were compared with those available in the literature.

Isomeric transitions in [sup 69]Se are investigated using charged particle-[gamma] and [gamma]-[gamma] delayed coincidence measurements. A precise three-point angular distribution shows that the decay of the 9/2[sup +] isomer is nearly isotropic, suggesting either significant dealignment during the lifetime of the isomer or a small [ital E]3 admixture in this transition. An improved measurement of the lifetime of the isomer yields a half-life of 960[plus minus]23 ns. The single particle level structure of negative parity states in [sup 69]Se below the 9/2[sup +] isomer is investigated using a recoil shadowing technique. A 39.4 keV gamma ray with a total-internal conversion coefficient of 28.0[plus minus]2.5 is observed deexciting the 5/2[sup [minus]] first excited state, which is found to be isomeric with a half-life of 2.0[plus minus]0.2 [mu]s. The observed lifetime, along with the internal conversion coefficient, suggests [ital E]2 multipolarity for this transition and strongly favors a spin and parity assignment of 1/2[sup [minus]] for the [sup 69]Se ground state.

The internal conversion coefficient for bound-free electron transition of originally energetically forbidden internal conversion processes induced by intense, few-cycle UV laser pulse of Gaussian shape in the case of isomers {sup 107}Ag{sup m} (K shell, E3, 25.47 keV), {sup 90}Nb{sup m} (L{sub 2} shell, M2+E3, 2.3 keV), {sup 183}W{sup m1}(M{sub 5} shell, E2, 1.79 keV), {sup 183}W{sup m2} (N{sub 1} shell, E1, 548 eV), and {sup 188}Re{sup m} (M{sub 2} shell, M3+E4, 2.63 keV), and {sup 235}U{sup m} (O{sub 4} and O{sub 5} shells, E3, 73.5 eV) is determined numerically. Experimental conditions and possibilities of the laser-induced internal conversion process of {sup 183}W{sup m2} from the N{sub 1} shell are discussed in more detail.

The most widely used theoretical internal conversion coefficient (ICC) tables are of Hager and Seltzer (HS), Rosel et al. and BRICC (Band et al. tables using BRICC interpolation code). A rigorous comparison of experimental ICCs with various theoretical tabulations is possible only when a large data on experimental ICCs is available at one place. For this reason, a compilation of all the available experimental ICCs, αT, αK, αL of E2 transitions for a number of elements in the range of 24⩽Z⩽94 is presented. Listing of experimental data includes 595 datasets corresponding to 505 E2 transitions in 165 nuclei across the nuclear chart. Data with less than 10% experimental uncertainty have been selected for comparison with the theoretical values of Hager and Seltzer, Rosel et al. and BRICC. The relative percentage deviation (%Δ) have been calculated for each of the above theories and the average (%Δ¯) are estimated. The Band et al. tables, using the BRICC interpolation code are seen to give theoretical ICCs clos...

The authors have designed a versatile and compact system which allows the simultaneous measurements of alpha - gamma and alpha -eK,L,M angular correlations and hence allows the determination of internal conversion coefficients. The capability of the system is illustrated by applying it to the study of the 227Th to alpha 223Ra* decay.

Precise line-shape analyses of M\"ossbauer spectra using the 58-keV transition in $^{159}\mathrm{Tb}$ have been made using an exact representation of the line shape in transmission. Spectra were made using a ${\mathrm{Dy}}_{2}$${\mathrm{O}}_{3}$ source at liquid-nitrogen temperature and absorbers of ${\mathrm{Tb}}_{4}$${\mathrm{O}}_{7}$ and ${\mathrm{TbAl}}_{2}$ at several temperatures from 81 to 297 K. We have measured the recoilless fraction as a function of temperature between 115 and 297 K for ${\mathrm{TbAl}}_{2}$ and at 81 and 294 K in ${\mathrm{Tb}}_{4}$${\mathrm{O}}_{7}$. If the theoretical value of the internal conversion coefficient of 11 is accepted, we cannot fit our results to a Debye model, even in a rough approximation. The mean lifetime of the first excited state of $^{159}\mathrm{Tb}$ was determined to be 77(1) ps. We have found the value of the interference parameter for this transition to be -0.0058(7), which appears larger in magnitude than predicted by theory.

We have carried out precise M\"ossbauer line-shape analyses in tungsten and iridium metal using an exact representation of the line shape in transmission. By using exceptionally intense sources (\ensuremath{\sim}70 Ci for $^{183}\mathrm{Ta}$) and carefully chosen constraints between sets of M\"ossbauer-effect spectra, we have been able to make a quantitative test of the theory of final-state effects. The temperature dependence of the recoilless fraction, ${\mathit{f}}_{\mathit{a}}$(T), for $^{183}\mathrm{W}$ in tungsten metal has been determined to about 1% accuracy, which is an order of magnitude better than previous M\"ossbauer or x-ray investigations, between 80 and 1067 K. The Debye model fits our results from 80 through 968 K, with a Debye M\"ossbauer temperature of 336.5 K, when a correction for thermal expansion is included. The recoilless fraction data were used to derive a value of 8.76(10) for the internal conversion coefficient for the 46.5-keV transition in $^{183}\mathrm{W}$, with an approach based on the quasiharmonic approximation to the lattice vibrations, which determines the temperature dependence of the recoilless fraction. The interference parameters, times 100, that we find in this investigation of $^{183}\mathrm{W}$ in tungsten metal (46.5 keV) and $^{191}\mathrm{Ir}$ in iridium metal (129 keV), are -0.317(6) and -0.77(10), respectively. These values are both greater in magnitude than the theoretically calculated values by about 10%, although the $^{191}\mathrm{Ir}$ case has errors large enough that the comparison with theory is inconclusive. These results differ with theory, and would indicate that the theoretical calculations of interference need refinement if they are to be used in studies of time-reversal invariance.

Using relativistic band structure calculations applying the relativistic linear muffin-tin orbital (RLMTO) method the internal conversion coefficient (ICC) for valence electrons of hcp−99Tc and bcc−235U are calculated. This coefficient describes the probability for a virtual -quantum of energy ħΩ (2.17keV for Tc, 77eV for U) emitted by a nucleus to eject an electron from the valence band (photoelectron emission with the photon source inside the solid). The resulting ICC's are very similar to the corresponding density of states.

The ab-initio electron theory of the internal conversion coefficient (ICC) is developed for the case of pure crystalline metals, the radioactive nuclei of which emit γ-quanta with relatively small energy (≦ keV) exciting thus preponderantly valence electrons. In this case the photon wavelength is large in comparison with the radius of the nucleus and the ICC ( = energy spectrum of the emitted conversion electrons) becomes independent of the properties of the nucleus. For any electric or magnetic transition and using spherically symmetric muffin-tin potentials the ICC is expressed by the characteristic quantitites of the electron making a transition from an occupied valence state to an unoccupied free electron state. The calculations for 110Ag show the ICC to reflect directly the density of states of the valence electrons. Die ab-initio Theorie des inneren Konversionskoeffiienten (ICC) wird fur den Fall reiner kristalliner Metalle entwickelt, deren radioaktive Kerne γ-Quanten mit relativ kleinen Energien emittieren, die folglich vorwiegend Valenzelektronen anregen. In diesem Fall ist die Photonenwellenlange gros im Vergleich zum Kernradius und das ICC ( = Energiespektrum der emittierten Konversionselektronen) wird unabhlangig von den Kerneigenschaften. Fur einen beliebigen elektrischen oder magnetischen Ubergang wird unter Verwendung spharisch-symmetrischer Muffin-tin-Potentiale der ICC durch die charakteristischen Grosen des Elektrons, das einen Ubergang von einem besetzten Valenzzustand in einen unbesetzten freien Elektronenzustand macht, ausgedruckt. Die Berechnung fur 110Ag zeigt, das der ICC direkt die Zustandsdichte der Valenzelektronen widerspiegelt.

Internal conversion coefficients involving atomic electrons (ICC) and electron-positron pairs (IPC) are often required to determine transition multipolarities and total transition rates. A new internal conversion coefficient data base, BrIcc has been developed which integrates a number of tabulations on ICC and IPC, as well as {Omega}(E0) electronic factors. To decide which theoretical internal conversion coefficient table to use, the accurately determined experimental {alpha}{sub K}, {alpha}{sub L}, {alpha}{sub Total} and {alpha}{sub K}/{alpha}{sub L} values were compared with the new Dirac-Fock calculations using extreme assumptions on the effect of the atomic vacancy. While the overall difference between experiment and theory is less than 1%, our analysis shows preference towards the so called ''Frozen Orbital'' approximation, which takes into account the effect of the atomic vacancy.

The activity of a 109Cd solution has been accurately determined without using 109Cd nuclear decay data such as emission probabilities. An ampoule containing this calibrated 109Cd solution was sent to the Bureau International des Poids et Mesures to include the activity result in the database of the International Reference System (SIR). The emission rate of conversion electrons was measured by means of pressurized proportional counters as well as by a liquid scintillation spectrometer. The combination of the results with the photon emission rate measured with the aid of γ-ray spectrometers yields the activity concentration. The measurement results were also used to deduce emission probabilities with high accuracy. For the 88 keV transition, a photon emission probability of p γ = 0.03663 ( 33 ) and a total internal conversion coefficient of α t = 26.30 ( 25 ) were determined.

The 10.5-day isomer in {sup 193}Ir decays by a single 80.2-keV M4 transition directly to the ground state of that nucleus. We have measured the total intensity of K x rays relative to 80.2-keV {gamma} rays for this transition to be 98.7(6). With the K-shell fluorescent yield for iridium taken to be 0.958(4), this result yields {alpha}{sub K}=103.0(8) for the K-shell internal conversion coefficient (ICC). The calculated {alpha}{sub K} for this transition is particularly sensitive to the treatment of the hole that is created by conversion in the atomic K shell. Recent ICC tables, which ignore the hole, yield {alpha}{sub K}=92.0. We demonstrate that calculations incorporating the hole produce values between 99.6 and 103.3 depending on the approximation used. Our result strongly supports the need to include the hole.

The HIGISOL facility has been used to investigate carefully the isomeric transition 228.5 keV in 80Y. We have measured the electron internal conversion coefficient for this transition αK = 0.50 ± 0.07 which gives the value for half-life of “bare” isomeric state T 1/2 = 6.8 ± 0.5 s. The isomeric state should play an important role in the rp-process calculations.

Özet. Süperağır çekirdekler için öncelikli bozunum modları, alfa yayınlanması ve kendiliğinden fisyondur. Diğer bir önemli mod ise, gama yayınlanması ile yarışan, dönüşüm elektron yayınlanmasıdır. Dönüşüm elektronlarının gama ışınlarına oranı olarak bilinen iç dönüşüm katsayıları, teorik ve deneysel nükleer yapı çalışmalarında önemlidir. Bu katsayılar deneysel ve teorik yollarla hesaplanabilmektedir. Ayrıca, bu katsayıların hesaplanması için geliştirilmiş pek çok bilgisayar programı da mevcuttur. Bu çalışmada, Z=126 atom numaralı Unbihexium (Ubh) süperağır çekirdeğine ait dönüşüm katsayıları, düşük geçiş enerji aralığında, E4 ve E5 (elektrik), M4 ve M5 (manyetik) geçişleri için, bir matematiksel model olan yapay sinir ağları metodu kullanılarak elde edilmiştir. Abstract. The primary decay modes for superheavy nuclei are alpha emission and spontaneous fission. Another decay mode is conversion electron emission which competes with the gamma-ray emission. Internal conversion coefficients, which are defined by the ratio of the number of emitted electron to the number of gamma-rays, are important for experimental and theoretical nuclear structure studies. These coefficients can be calculated by many experimental and theoretical ways. Furthermore, there are many computer code for calculations of these coefficients. In this work, the conversion coefficients belonging to the super heavy Unbihexium (Ubh) whose atomic number is 126 were calculated for E4 and E5 (electric), M4 and M5 (magnetic) multipole orders in the transition in low energy range. For the calculations, a mathematical model artificial neural network method was used.

A new measurement of the total internal conversion coefficient of the 279 keV transition following the decay of 203Hg resulted in alpha = 0.2250(12).

The total internal conversion coefficient of the 479.53 keV M4 transition in 90mY reported by Krishna Murty et al. (1989) is shown to be incorrect. The corrected value is 0.102+or-0.004. It is shown that in this case the total internal conversion coefficient is inadequate to verify the purity of the transition.

The 1s β − decay of 96 Sr was studied with γ-γ coincidences, internal conversion coefficient measurements and γγ(θ) angular correlations. The 96 Sr activity was obtained as a result of β − decay of 96 Rb which was produced by the OSTIS mass separator. The α k internal conversion coefficients were determined for 5 of the most intense transitions between levels in 96 Y. Angular correlations were deduced from gammas coincident with the 122.3 keV and 530.0 keV transitions in 96 Y. A level scheme of 96 Y is proposed and definite spin-parity assignments are made for 5 levels. The scheme is discussed within the context of level systematics of odd-odd Y isotopes.

The decay of115m In has been investigated using accurate counting methods. The emission rate of conversion electrons plusβ −-particles was determined with a 4π proportional flow counter. The total andK-shell internal conversion coefficients of the 336 keVγ-ray in115In were measured by the electron X-ray coincidence method using combinations of a Si surface barrier with a NaI(Tl) detector and of a magneticβ-spectrometer with a high energy resolution Si(Li) detector, respectively. The conversion ratioR=K/(L+M+...) was deduced from electron spectra recorded with the magneticβ-spectrometer. The 336 keVγ-ray emission rate of all used sources was determined with a calibrated NaI(Tl)γ-ray spectrometer. A Ge(Li) detector has been used to determine the relative intensity of the 497 keVγ-ray in115Sn. As results have been deduced the 336 keVγ-ray emission per decay (N γ1/N 0=(45.9 ± 0.1)%), the total internal conversion coefficient (α=1.073 ± 0.014), theK-shell internal conversion coefficient (α K=0.843±0.012), the conversion ratioR=3.63±0.07, theβ −-transition per decay going to the ground state (N β1/N 0=(5.0 ± 0.7)%) and to the first excited level in115Sn115Sn(N β2/N 0=(0.047 ± 0.002)%), and the 497 keVγ-ray emission (N γ2/N γ1=(0.103 ± 0.004)%). From the obtained internal conversion data it follows that the 336 keVγ-ray transition is ofM4 character with anE5 admixture of less than (3.5±1.5)%. The half-life of the isomeric state115 mIn has been determined with four different methods. The result isT 1/2=(4.486±0.004) h.

Optical excitation of an atom containing an isomeric nucleus should affect its internal conversion coefficient through modification of its bound-state electronic wave functions as well as by interaction with the outgoing electron. The extreme case of $^{235m}\mathrm{U}$, which decays entirely by internal conversion and for which pronounced environmental effects on the half-life have been observed, is considered. Resonant (bound-state) effects on the lifetime and electron emission spectrum are predicted to occur with moderate-power cw laser irradiation.

An ICC computation for the 14.4 keV transition in57Fe has been made using relativistic wavefunctions derived from spin polarized UHF wave functions of atomic iron. It is shown that ICC and electron density at the nucleus are proportional for polarized s electrons as has been found already for unpolarized electrons.

The decay of1 /sub 56//sup 48/Ba/sub 92/ to levels of odd-odd 1 /sub 57//sup 48/La/sub 91/ has been studied in experiments where ..gamma..-ray singles, time-dependent ..gamma..-ray spectra, and ..gamma gamma..t coincidence spectra were collected. The /sup 148/Ba activity was produced directly by on-line mass separation. The half-life of /sup 148/Ba was determined to be 0.61 +- 0.03 s. A level scheme containing 26 levels and 63 ..gamma.. rays is proposed for /sup 148/La. Spin and parity for several low-lying levels are assigned on the basis of internal conversion coefficient measurements and ..beta..- and ..gamma..-ray branching. A half-life of 67 +- 4 ns is measured for the 56-keV level. Several features of the level scheme are discussed and compared to neighboring La isotopes and N = 91 isotones.

/sup 6/7/sub 3/2Ge/sub 3/5 has been studied via the reaction /sup 6/4Zn(..cap alpha..,n..gamma..)/sup 6/7Ge. The mass excess was measured to be -62666 +- 12 keV, and four low-lying excited states have been identified. Among these newly identified levels is an isomeric state at 18.2 keV having a measured total mean lifetime of 18.5 +- 0.3 ..mu..s and a measured K-shell internal conversion coefficient ..cap alpha../sub K/ = 176 +- 29. In addition, the total lifetime of the 63.4 keV isomeric level in /sup 6/5Ni has been measured to be 104.9 +- 7.1 ..mu..s. The level schemes of the six nuclei /sup 63,66/Ni, /sup 65,67/Zn, and /sup 67,69/Ge are then compared, and similarities in their structure and in the decay characteristics of the isomeric states of each are discussed and interpreted in terms of a simple pairing model.

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+Ae) (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 (IK 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.

A microfoil internal conversion electron (MICE) detector is described which permits direct Doppler shifting of resonance radiation up to velocities of ± 20 cm/s, and gives large improvements in signal-to-background ratios for many Mossbauer isotopes, when compared with transmission geometry. The detector described has efficiency of nearly unity, and it allows for cooling the reciprocating microfoil module to 100 K, which improves signal-to-background substantially over room temperature operation. We give an analysis of the signal-to-background that can be expected for this MICE detector, and for a corresponding transmission experiment. In a table of neutron produced isotopes we find more than 10 cases which are favorable to the MICE approach as compared with the more conventional transmission geometry. The signal-to-background enhancement predicted for several Mossbauer isotopes is substantial for the MICE geometry compared to transmission geometry. Direct measurements of the Mossbauer conversion electron spectrum for the 46.5 and 99.1 keV transitions of 183 W and the 100.1 keV transition in 182 W are reported and compared with our analysis. In the case of 183 W (46.5 keV) we observe over 500% signal-to-background, and this experimental result agrees well with our analysis of the expected size of the effect. Satisfactory agreement is also found for the 99.1 keV 183 W and 100.1 keV 182 W spectra. Based on the analysis given it is possible to determine nuclear resonance cross sections and thereby infer internal conversion coefficients for the resonance transitions. Thus, we are able to determine the internal conversion coefficient for the 46.5 keV transition in 183 W to be α = 13 ± 3.

The internal conversion process of the 165.8 keVγ-ray transition in the decay of139Ce has been reinvestigated. The emission rate of the K-shell internal conversion electrons was determined by an (electron)-(X-ray)-(X-ray) triple coincidence experiment using a magneticβ-spectrometer and two Si(Li) detectors. From electron spectra recorded as a function of momentum conversion electron ratios were also determined. The disintegration rate of the sources has been taken from 4πβ-γ coincidence experiments. The following results were obtained: the probability for internal conversion in theK-shellkK=0.1719±0.0020 and the conversion ratiosK/(L + M+...=5.84±0.17,K/L=7.45±0.20, andL/(M+...)=3.63±0.29. The internal conversion coefficients deduced area=(0.2520+0.0050),αK=(0.2152±0.0033), andαL=(0.0289±0.0012). The results are in good agreement with previous experimental values and with theoretical data calculated for a M1 transition of 165.8 keV in139La.

The radioactivity concentration of samples of the same solution of 139Ce has been measured by 22 national and international laboratories. In most cases a 4π proportional gas flow counter (with atmospheric of higher pressure) or a liquid scintillation counter was used in coincidence with a NaI scintillation detector. The results are presented in tabular and graphical form. Brief explanations are given regarding the solution distributed, the preparation of sources and the equipment used. Some remarks concerning coincidence formulae and efficiency extrapolation are added. As a by-product, the total internal conversion coefficient for the 166 keV transition of 139La has been determined as α=0.2502±0.0025.

The beta - and electron-capture branching ratios in the decay of 180mTa and the K internal conversion coefficient of the 93 keV lambda ray were deduced from coincidence measurements between beta -, lambda and K X-rays and a measurement of the relative lambda -ray intensities. The uncertainties in the branching ratios were estimated by a Monte-Carlo technique. The half-life of 180mTa was also measured as (8.152+or-0.006)h.

The 1.87 hours 543.7 keV (7+) isomeric state in198Tl is produced via197Au(α, 3n)198mTl (Eα=35 MeV) reaction. The total conversion coefficient of 260.9 keV (7+→3−) is determined for the first time by the intensity balance method. The value of\(\alpha _{\rm T} \left( {260.9 keV} \right)\) is found to be 40.1±8.6 which is in good agreement with the theoretical value of Hager and Seltzer for pureM4 transition. The gamma transition probability of the 260.9 keV (M4) is calculated using the present value of αT and compared with the single-particle estimate.

The total conversion coefficient of the 165.853 keV transition in 139 La has been determined to be 0·251 ± 0·002 from measurements of the electron and gamma-ray intensities and the source activity. From the X-ray and γ-photon spectra the probability P K ω K has been determined to be 0·639 ± 0·006. Using α T = 0·251 ± 0·002, α K = 0·214 ± 0·002, ω K = 0·906 ± 0·026 and P K ω K = 0·639 ± 0·006 the number of K -X rays and 166 keV photons per disintegration has been calculated to be 0·794 ± 0·009 and 0.799 ± 0·001 respectively, giving a K -X ray to γ-photon ratio of 0·99±0·01. The discrepancy between the experimental and theoretical conversion coefficients is explained by taking the nuclear structure effect into account.

The cross sections for the reactions 113In(n,2n) and (n,n') and 115In(n,n'), (n,p) and (n, alpha ) at 14 MeV, and 115In(n,2n) from 14 to 18 MeV were measured by the activation technique. Special emphasis was placed on the accuracy of the results, and so full experimental details are included. The correlations between the measurements are considered, these being especially important for 112m,gIn. Isomeric cross section ratios were measured at 14.3 MeV: sigma m/ sigma g=(4.32+or-0.20) for 113In(n,2n)112m,gIn and sigma m/ sigma g=(4.59+or-0.03) for 115In(n,2n)114m,gIn. The results were compared with other published values, which show a very wide spread so that these cross sections cannot be considered well known at the present time. During the course of this work half-lives were measured for 112gIn((14.97+or-0.10)min), 112mIn((20.56+or-0.06)min) and 114In((71.6+or-0.1)s). The decay scheme of 114mIn was investigated, and gamma -ray intensities and a total internal conversion coefficient of (5.101+or-0.061) for the 190 keV gamma ray were obtained. In the case of 112mIn arguments are presented to support the theoretical total internal conversion coefficient for the 156 keV gamma ray of 6.80.

A general formula for the laser-assisted internal conversion coefficient valid for all electronic shells and an approximation for near threshold laser-assisted internal conversion coefficient are deduced. The weak laser field and low frequency limits of the result are discussed. Numerical examples of the approximated, near threshold laser-assisted internal conversion coefficients are also given.