Conversion Electron Intensities Research Articles

Precise conversion electron intensities of low energy gamma transitions for efficiency calibration of electron detectors

Precise energies and relative intensities of gamma transitions and conversion electrons in the electron capture decay of 153Gd have been determined independently with our well-tested and optimized gamma and electron spectrometers - a large-volume (60 cc) HPGe detector and a mini-orange electron transporter paired to a Si(Li) detector, respectively. The experimental internal conversion coefficients of the gamma transitions in 153Eu have been determined using Normalized Peak to Gamma method and compared with the theoretical values adopted by Nuclear Data Sheets to assign multipolarities of all the transitions. The precise internal conversion electron intensities of the low energy transitions can be used as standards for calibration purposes of electron detectors and spectrometers.

Precision Measurements of Internal Conversion Coefficients of Low Energy Transitions in $${}^{169}$$Tm for Efficiency Calibration of Electron Detectors

The 32.018 d beta decay of $${}^{169}$$ Yb is studied with a high resolution precisely calibrated 8 $$K$$ PC based Multi-Channel Analyzer coupled HPGe gamma spectrometer system and liquid nitrogen cooled Si(Li) detector coupled to a well calibrated Mini-Orange magnetic spectrometer. Precise energies and relative intensities of gamma transitions and conversion electron intensities of gamma transitions have been determined for the first time with better accuracy. The experimental internal conversion coefficients of the gamma transitions in $${}^{169}$$ Tm have been determined using Normalized Peak to Gamma method and compared with the theoretical values adopted by Nuclear Data Sheets to assign multipolarities of all the transitions. The precise internal conversion electron intensities of the low energy transitions can be used as standards for calibration purposes of electron detectors and spectrometers.

Precision electron–gamma spectroscopic data from the beta decay of 153Sm

Abstract The decay of 153Sm was studied with a HPGe detector and a Si(Li) detector based electron transporter. Forty four gamma transitions belonging to sixteen excited levels in the daughter nucleus 153Eu were analyzed for their energies, emission intensities, conversion electron intensities and conversion coefficients. These values have resulted in the determination of precise beta emission intensities to the levels in 153Eu and in the construction of an internally consistent decay scheme. The present study will add to the decay data available on this radionuclide for reliable dose estimations for medical applications.

Conversion electron measurements and determination of rotational parameters in 177Lu and 177Hf

Conversion electron and gamma spectroscopic measurements were carried out on the 160.44d 177mLu decay with a mini-orange electron transporter coupled to a Si(Li) detector and a large-volume HPGe detector. Conversion electron intensities and internal conversion coefficients of 32 transitions in the two nuclei were obtained by the Normalized Peak to Gamma method. Of these, many are being reported for the first time. Mixing ratios were determined for the M1 + E2 transitions of the rotational bands 7/2+[404] in 177Lu , 7/2−[514] and 9/2+[624] in 177Hf populated by the isomer’s decay. The value of the rotational parameter |(gK − gR)/Q0| was calculated for all the three bands. A revised decay scheme is proposed for 177mLu .

Decay of 152Tb and E0 and M1+E0 transitions in 152Gd

The decay of 152Tb has been investigated by means of measurements of singles γ-spectra and γ—gamma coincidence experiment. The 704 transitions were observed, of which 347 were identified to the decay of 152Tb for the first time. Using the more precise and full data about intensities of gamma-transitions and previously reported conversion electron intensities of the E0 or M1+E0 multipolarities were established for several transitions. The revised decay scheme consists of about one hundred excited levels from which 46 levels were introduced for the first time.

Level structure studies of 182W from the decay of 182Ta

The relative intensities of X rays and γ rays from the decay of 182Ta were measured precisely using Si(Li) and HPGe detectors. The intensities of the different components of K and L X rays were measured for the first time. The conversion electron intensities for the transitions with energy above 800 keV from the 182Ta decay were measured using a mini-orange electron spectrometer and the internal conversion coefficients for various transitions in 182W deduced. The (M + N)-conversion coefficients for the 1001.7, 1189.1, 1231.0, 1257.2, 1289.2, and 1342.7 keV transitions in 182W were measured for the first time. Also, γ–γ coincidence and correlation measurements were carried out using a HPGe–HPGe coincidence setup (2τ = 7 ns). The directional correlation coefficients for the 928–229, 960–229, 1002–229, 1044–229, 1158–229, 1223–229, and 1002–222 keV cascades in 182W are determined for the first time. The multipole mixing ratio for the 152, 156, 179, 222, 928, 1002, 1113, 1158, 1223, and 1231 keV transitions are deduced from the present directional correlation and conversion coefficient measurements. Experimental ratios of reduced transition probabilities for the transitions in 182W from positive and negative parity states are deduced and compared with the values predicted by the symmetric rotor model. From this comparison a unique K assignment of Kπ = 1+ and Kπ = 1− is made to the bands built on the 1257 and 1553 keV levels, respectively.

The level structure of 87Nb

The level structure of 87Nb has been studied through β-decay of 87Mo activity produced by the 58Ni(32S, 2pn) reaction and through in-beam γ-ray measurements in the 58Ni(32S, 3pγ)87 Nb reaction. In the β-decay study, the decay scheme of 87Mo is constructed firstly from γ-ray energies, intensities of γ-rays and conversion electrons, and γ-, βγ- and γ(ce)-coincidence relations. Spins and parities of the low-lying statesof 87Nb and 87Zr were also investigated. In the in-beam study, intensities, coincidence relations and angular distributions of γ-rays were measured in coincidence with charged particles evaporated from the compound nuclei. Then high-spin states of Jπ ⩽ (33+2) in 87Nb were established in this study. Systematic behavior in the level structures of N = 46 isotones, and the comparison between those of 85Y and 87Nb, are discussed.

Precision measurements of conversion electrons in 125Sb, 152Eu and 160Tb decays

Wide-spreading use of mini-orange electron spectrometers in conversion electron spectroscopy necessitates the standardization of a few commonly available radio-isotopes for transmission calibration of the spectrometer. With this motivation, the intensities of conversion electrons emitted following 125Sb, 152Eu and 160Tb decays have been investigated using a precisely calibrated mini-orange electron spectrometer. Some experimental aspects of optimization and transmission calibration are discussed. In addition, results for many weak transitions are reported for the first time.

Recommended data on selected gamma-ray and conversion-electron calibration sources

A compilation of experimental energies and relative intensities for gamma-ray and conversion-electron transitions from the decay of 207Bi, 152Eu, 133Ba, 56Co, and 66Ga is presented. In the cases of known transition multipolarities and mixing ratios calculated values are given for the conversion-electron intensities. Often, these calculated values are more reliable than the measured ones.

K and total internal conversion coefficients of the 1063.6 keV M4 transition of 207Pb

Precise K and total internal conversion coefficients for the 1063.6 keV transition as well as γ- and K conversion electron intensity ratios of the 1063.6 and 569.6 keV transitions of 207Pb are derived from earlier measurements. The recommended values are αK1063 = 0.0945 ± 0.0022, αT1063 = 0.126 ± 0.003, Iγ1063Iγ569 = 0.758 ± 0.004 andIe1063Ie569 = 4.58 ± 0.05. Both internal conversion coefficients deviate slightly from the theoretical values as expected.

The states of 73Se populated by the beta decay of 73Br

Abstract Decay of mass-separated samples of the nuclide 73Br have been investigated by means of an on-line isotope separator in the tandem accelerator laboratory of Kyushu University. Twenty eight γ-rays were assigned to the decay of 73Br. The half-life was measured to be 3.4±0.22 min. The decay scheme of 73Br was constructed on the basis of γ-ray energies, intensities of γ-rays and conversion electrons, and relations of γγ-, βγ- and γ(ce)-coincidences. Spins and parities of the ten levels of 73Se were assigned or limited according to log ƒt values, conversion coefficients and branching ratios of the transitions. Systematical trends in the level schemes of N=39 isotones 69Zn, 71Ge, 73Se, 75Kr and 77Sr are discussed.

M1 transitions from the gamma band and F-spin mixing in [formula omitted

The M1 strength in a number of γ → g transitions in 168Er have been determined from high-precision L-subshell conversion electron intensity measurements. The results are combined with earlier data for transitions within the γ-band and compared with the predictions of an IBA-2 calculation. It is shown that a satisfactory description of both E2 and M1 properties can be obtained with the appropriate degree of F-spin symmetry breaking in the hamiltonian, which in turn relates to the degree of neutron-proton symmetry in the collective wavefunction.

Analysis of the properties of excited states in 165Er

An analysis of 165Tm decay has shown that precision measurements of the γ-ray and internal conversion electron intensities, in combination with angular correlation measurements, provide additional data useful for the determination of the mixing and intensity ratios of γ-transitions with a small energy difference. The spin of the 589.868 keV state is found to be I π = 1 2 − . Doublet opposite-parity transitions from states at 1103.495, 920.632 and 745.968 keV to levels near 590 keV with an energy difference ΔE = 108 ± 22 eV are identified.

Nature of the 153 and 270 keV Transitons in119Sb from119mTe

The 153 and 270 keV transitions in 119 Sb have been investigated for the presence of any anomalous conversion through conversion electron intensity and conversion-electron gamma and gamma-gamma directional correlation measurements. The resulting subshell ratios and particle parameters have been analysed for the accurate determination of mixing ratios for the transitions. The results are δ 153 =±0.0025 and δ 270 =0.10± 0.03 0.20 . The conversion process has been found to be normal in both cases.

Gamma-ray transition strengths and multipolarities in the doubly odd nucleus132I

The half-lives of levels in 132I were measured as 7.14(14) ns (49.7 keV) 3.57(7) ns (161.5 keV) and 1.42(2) ns (277.9 keV). In the measurement of the 161.5 keV level half-life the relative order of the 116.3-111.8 keV transitions was established. The value for the 49.7 keV level is in marked disagreement with previous results and integral and differential directional correlations confirmed the new and much longer value. Relative gamma -ray intensity results were combined with published internal conversion electron intensity data to yield relative ICC's and to permit multipolarity mixing intensities to be deduced.

Study of gamma magnetic resonance by selective electron Mossbauer spectroscopy

The Mossbauer conversion electron process is investigated. The formula of the intensity of the Mossbauer conversion electrons is obtained using density matrix of an electron-nuclear system. It is shown that selective Mossbauer conversion electron spectroscopy may be applicable in gamma magnetic resonance studies.

Relative intensities of γ-rays from E2 transitions in the decay of 180mHf

The relative intensities of γ-rays from pure E2 transitions in the decay of 180mHf have been determined from measured conversion electron intensities and calculated K- and L-shell conversion coefficients.

Observation of a fast 2+ → 0+′ transition in 98Mo

Abstract Multiple Coulomb excitation of the 734.6 keV 0 +′ level in 98 Mo has been observed by the detection of its E0 decay. The conversion electron intensity was measured relative to that of the ground state decay of the 787.5 keV, 2 + level. A large reduced E2 transition probability of B (E2, 0 +′ → 2 + ) = 0.293±0.014 e 2 · b 2 is found, which exceeds the prediction of the model of nuclear surface vibration by nearly a factor of three.

Studies of ?-ray transitions in171Yb

The decay of171Lu(t1/2=8.2 day) to the levels of171Yb has been studied using large volume high resolution Ge(Li), x-ray Ge(Li) and NaI(Tl) detectors.γ-γ coincidence and directional correlation experiments have been performed. Spin-parity of 5/2−, 7/2+, 5/2−, 9/2+, 7/2−, 7/2−, 11/2+, 9/2−, 9/2− and 5/2− have been assigned to the 75.87, 95.26, 122.37, 167.62, 208.00, 230.61, 259.02, 835.21, 948.37 and 1024.87 keV levels respectively. Several new coincidence relations have been observed in the present work. Two newγ-transitions at 141.45 and 821.30 keV observed and two levels at 766 and 944 keV been proposed. Multipolarity assignments have been made for most of theγ-transitions from theK-shell internal conversion coefficients obtained using the presentγ-ray intensities and the published conversion electron intensities. A revised level scheme for171Yb has been proposed and compared with published data.

Search for a 11/2??3/2+ M 4 transition in141Sm

The electromagnetic decay of the 11/2−141mSm is investigated. Internal conversion electron and X-ray-conversion electron coincidence measurements indicate that the state undergoesβ+ and electron capture decay with 99.69% strength and the remaining 0.31% goes to a 174.2±0.3 keVM4 transition. TheK/L conversion electron intensity ratio for the transition is measured to be 1.7±0.4. The energy of the 11/2− is established at 175.8±0.3 keV above the 1/2+ ground state in141Sm. Systematics of theM4 transitions in theN=79 and 81 isotones are discussed.