Internal Conversion Coefficients Research Articles

Evaluation of 234Th nuclear decay data

(234)Th is a naturally occurring radionuclide being the daughter of (238)U. This paper presents the results obtained in a new evaluation of the nuclear data characterizing the (234)Th radioactive decay. The following decay characteristics have been evaluated: half-life, energies and probabilities of beta and gamma-ray transitions, internal conversion coefficients, energies and emission probabilities of gamma-rays, X-rays, conversion and Auger electrons. Some evaluation difficulties encountered have been pointed out. A new recommended absolute emission probability of 3.75 (8)% has been proposed for the main 63.3-keV gamma-ray in the (234)Th decay. Some practical considerations of the (234)Th activity determination by gamma-ray spectrometry are also presented.

Methods of monitoring the consistency of sets of recommended data for the decay characteristics of radioactive nuclides

Methods and procedures for monitoring the consistency of sets of recommended data for radioactive nuclide decay characteristics are considered. A procedure is proposed, which combines three methods of checking the consistency of quantities related to the decay scheme of a radionuclide: the decay energy, the energies and probabilities of nuclear transitions, the internal conversion coefficients and the energies and emission probabilities of the radiations accompanying the decay.

Nuclear Data Sheets for A = 198

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 198Ir, 198Tl nuclei and identification of new superdeformed bands in 198Pb and 198Po.

Evaluation the decay data of 153Gd

153Gd decays to the excited states of 153Eu through the electron capture decay mode. The evaluation of the complete decay scheme and data of 153Gd including the recent new measurements are presented in this report. The limitation of relative statistical weight method (LRSW) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 239.47±0.07 days. All known measured γ-ray relative emission probabilities have been examined. And the γ-ray emission probability of the reference γ line of 97.431 keV is recommended to be 29.5±0.5%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new 153Gd decay scheme was re-built.

Absolute E3 and M2 transition probabilities for the electromagnetic decay of the $\mathrm{\ensuremath I^{\pi}=K^{\pi}=8^{-}}$ isomeric state in 132Ce

The decay of the \(\ensuremath I^{\pi}=K^{\pi}=8^{-}\) isomeric state at 2340keV in 132Ce has been investigated in the 120Sn(16O, 4n)132Ce reaction. The measurements were carried out in e -\( \gamma\) and \( \gamma\) -\( \gamma\) coincidence modes using an electron spectrometer coupled to the OSIRIS II gamma-ray array at the Heavy Ion Laboratory of the University of Warsaw. Experimentally obtained internal conversion coefficients for the \(\ensuremath 8^{-} \rightarrow 6^{+}\) and \(\ensuremath 8^{-} \rightarrow 5^{+}\) transitions allowed the multipolarities, mixing ratios, reduced transition probabilities and hindrance factors to be determined.

The first observation of a deformed [formula omitted] ground-state band in 100Nb and the high-spin level scheme of its 4 n fission partner 148La

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.

Lattice effect in solid state internal conversion

The effect of the crystal lattice on nuclear fusion reactions p+d{yields}{sup 3}He taking place in internal conversion channels is studied. Fusionable particles solved in the investigated crystalline material form a sublattice. Fusion reaction is generated by a flux of incoming fusionable particles. The calculated cross sections are compared with those of an ordinary fusion reaction. The internal conversion coefficients are also calculated.

Evaluation of 235U decay data

Evaluation of the complete decay scheme and data for 235U including new measurements are presented in this report; literature data available up to June 2008 are included. The half-life is determined to be (7.04±0.01)×108yr. All known measured γ-ray absolute intensities have been examined; the γ-ray emission probability of the reference γ-ray line of 185.72keV is recommended to be 57.0±0.3%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new decay scheme for 235U is presented.

Characterization of the32 μs isomer inPb189as a shears-mode bandhead

Internal conversion coefficients have been measured for transitions following the decay of the 32 \ensuremath{\mu}s isomer in the neutron-deficient isotope $^{189}\mathrm{Pb}$. The main branch at 337 keV to the $25/{2}^{+}$ excited state is shown to be of $E3$ multipolarity with a strength of about 24 W.u. This, together with multipolarity assignments to other branches, leads to a spin and parity assignment of ${K}^{\ensuremath{\pi}}=31/{2}^{\ensuremath{-}}$ for the 2435-keV state. This also defines that state as the isomer, rather than the lifetime being due to feeding from a higher lying $33/{2}^{+}$ isomeric state as had been proposed previously. The isomer is suggested to arise from the partially aligned coupling of the ${11}^{\ensuremath{-}}$ two-proton configuration with the ${i}_{13/2}$ neutron hole. The low-lying nature of the ${31/2}^{\ensuremath{-}}$ multiplet member is attributed to the change in quasiparticle character of the ${i}_{13/2}$ neutron configuration as the neutron shell is depleted.

New level schemes and octupole correlations of light neutron-rich lanthanum isotopes 143,144La

The yrast and near-yrast level scheme of light neutron-rich 143La ( Z = 57 , N = 86 ) is reinvestigated and expanded and that of 144La ( N = 87 ) is proposed for the first time by measuring prompt γ rays from the spontaneous fission of 252Cf at Gammasphere. Spins/parities are assigned to the lowest-lying levels of 143,144La based on the early studies of β − decay, and the assignments for high-spin levels of 143,144La are made by measuring internal conversion coefficients and following the level systematics of the neighboring heavier La isotopes and even–even Ba and Ce nuclei. The B ( E 1 ) / B ( E 2 ) ratios, energy displacements δ E ( I ) and rotational frequency ratios ω − ( I ) / ω + ( I ) of the new parity-doublets of 143,144La indicate that octupole deformations/correlations also develop in these nuclei. The band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in 143La but being absent in 144La are interpreted as due to alignment of a pair of i 13 / 2 neutrons in 143La.

Evaluation of 133Xe and 133Xe m decay data

This paper presents the decay data evaluation of 133Xe and 133Xe m, which includes the most recent available data, such as half-life results and gamma-ray intensities that have not been considered in previous evaluations. The adopted internal conversion coefficients (ICC) have been calculated using the ‘Frozen Orbital’ approximation and are compared here to recent measured values. Recent Q-value tabulations, recommended gamma-ray energies for calibrations, as well as new evaluated gamma-ray intensities for the 81- and 233-keV lines (37.0 (3)% and 10.16 (13)%, respectively) are also presented in this evaluation. Atomic radiation emission probabilities (X-ray and Auger electron) associated with nuclear radiations have been deduced and also included in this work.

Internal conversion coefficients of high multipole transitions: Experiment and theories

A compilation of the available experimental internal conversion coefficients (ICCs), α T, α K, α L, and ratios K/L and K/LM of high multipole ( L > 2) transitions for a number of elements in the range 21 ⩽ Z ⩽ 94 is presented. Our listing of experimental data includes 194 data sets on 110 E3 transitions, 10 data sets on 6 E4 transitions, 11 data sets on 7 E5 transitions, 38 data sets on 21 M3 transitions, and 132 data sets on 68 M4 transitions. Data with less than 10% experimental uncertainty have been selected for comparison with the theoretical values of Hager and Seltzer [R.S. Hager, E.C. Seltzer, Nucl. Data Tables A 4 (1968) 1], Rosel et al. [F. Rösel, H.M. Fries, K. Alder, H.C. Pauli, At. Data Nucl. Data Tables 21 (1978) 91], and BRICC. The relative percentage deviations (%Δ) have been calculated for each of the above theories and the averages ( % Δ ¯ ) are estimated. The Band et al. [I.M. Band, M.B. Trzhaskovskaya, C.W. Nestor Jr., P.O. Tikkanen, S. Raman, At. Data Nucl. Data Tables 81 (2002) 1] tables, using the BRICC interpolation code, are seen to give theoretical ICCs closest to experimental values.

Internal conversion coefficients inCs134,Ba137, andLa139: A precise test of theory

Recently we measured the ratio of $K$-shell internal conversion coefficients, ${\ensuremath{\alpha}}_{K}$, for the 127.5-keV $E3$ transition in $^{134}\mathrm{Cs}$ and the 661.7-keV $M4$ transition in $^{137}\mathrm{Ba}$. We here report a measurement of the 165.9-keV $M1$ transition in $^{139}\mathrm{La}$, based on which we convert our earlier ratio measurement into individual ${\ensuremath{\alpha}}_{K}$ values for the transitions in $^{134}\mathrm{Cs}$ and $^{137}\mathrm{Ba}$. These results continue to confirm the Dirac-Fock calculations of internal conversion coefficients that incorporate the atomic $K$-shell vacancy.

Evaluation of theoretical conversion coefficients using BrIcc

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(E0) 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 1–6000keV 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.

Measurement of conversion coefficients in normal and triaxial strongly deformed bands inLu167

Internal conversion coefficients have been measured for transitions in both normal deformed and triaxial strongly deformed bands in $^{167}\mathrm{Lu}$ using the Gammasphere and ICE Ball spectrometers. The results for all in-band transitions are consistent with $E2$ multipolarity. Upper limits are determined for the internal conversion coefficients for linking transitions between TSD Band 2 and TSD Band 1, the ${n}_{w}=1$ and ${n}_{w}=0$ wobbling bands, respectively.

Assessment of internal conversion coefficients for anomalous electric dipole transitions

Sound quantitative knowledge of internal conversion coefficients (ICCs) is important when establishing decay schemes. ICCs are normally derived from efficiency tables and calculation, but for anomalous transitions and some electric dipole transitions (E1) in particular, theoretical values can differ considerably from the few available measured values. Experimentally measured ICCs and their ratios have been compiled, and these data have been used to propose a method based on the existence of measured ratios to determine the total ICC for such transitions. Comparisons have been made with the existing measured values, and good agreement was observed within the uncertainty limits.

Precise tests of internal-conversion theory

Using the 165.9-keV M1 transition in 139La as a calibrant, we have determined the K-shell internal conversion coefficients (ICCs) for the 127.5-keV E3 transition in 134Cs and the 661.7-keV M4 transition in 137Ba to 0.6% precision. Unlike previous less-precise measurements of these ICCs, which differed significantly from calculated values, our results agree well with calculations that include the atomic K-shell vacancy and disagree with those that exclude it. These results, which are consistent with what we also found for 193Ir, confirm our earlier conclusions but for different energies, multipolarities and atomic numbers.

Evaluation of decay data of 213Bi

213Bi disintegrates (97.91±0.03) % by β emission to the levels in 213Po, and (2.09±0.03) % through α decay to 209Tl. The evaluation of the complete decay scheme and data of 213Bi including the recent new measurements are presented in this report. The Limitation of Relative Statistical Weight Method (LWM) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 45.59±0.06 minutes. All known measured gamma-ray relative emission probabilities have been examined. And the gamma-ray emission probability of the reference γ line of 440.44keV is recommended to be (26.1±0.3) %. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new 213Bi decay scheme was re-built.

A new synthetic formalism for true coincidence summing calculations

Simultaneous detection in one sensing crystal of photons emitted in cascade from the same radioactive atom gives rise to true coincidence summing effects (excess and deficit counting). Presented in this paper is a general formula to correct for true coincidence summing. This analytical formula enables calculation of the correction factor and its associated uncertainty for any gamma-ray placed in a decay scheme of any radionuclide (all decay modes treated) in any measuring configuration. It takes account of any cascade of photons either through the nature of the involved photons (γ-rays, X-rays, and annihilation photons) or the unlimited number of photons emitted in cascade. The requirement for this calculation is twofold. From the radionuclide part, theoretical knowledge of the decay scheme is necessary along with its characteristics (gamma-ray intensities and internal conversion coefficients for instances). Some atomic quantities such as fluorescence yields have also to be known. From the detector part, calibrations for full-energy peak efficiency and total efficiency in the measuring configuration have to be available. The demonstration of the formula is done with restrictive conditions (point source, no angular correlation, and no metastable state between the initial and final energy states) but adaptation can be implemented to partially or totally lift these limitations or approximations. Implementation of the formula in a computer code named Coincal is mentioned. Its successful application to point sources of 152Eu placed 10 cm and 15 mm away from an n-type coaxial HPGe detector with 60% relative efficiency is also described.

Evaluation of 225Ac decay data

Evaluation of the complete decay scheme and data for 225Ac including new measurements are presented in this report; literature data available up to March 2006 are included. The half-life is determined to be 10.0±0.1 days. All known measured γ-ray relative intensities have been examined; the γ-ray emission probability of the reference γ-ray line of 150.04 keV is recommended to be 0.693±0.012%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally, the new decay scheme for 225Ac is presented.