Decay Of 152Eu Research Articles

The Correlations between the Emission Probabilities of the More Intense Gamma Rays in 152Gd and 152Sm Following 152Eu Decay

The variance matrix between the emission probabilities of the strong gamma-rays following the β decay of 152Eu were determined in a specially designed experiment. The emission probabilities are deduced from the decay scheme, whose branching-ratios and beta feeding fractions were fitted to the observed peak areas.

K-capture probabilities in the decay of152Eu

K-capture probabilities in the decay of152Eu

K-capture probabilities in the decay of75Se

A high-resolution HPGe detector was used to determine theK-capture probabilities in the decay of152Eu. ThePK values leading to 1529 keV, 1233 keV, 1085 keV levels in the daughter nucleus were determined by the sum peak method. ThePK value leading to the level at 1085 keV is determined for the first time.PL values for the three levels are deduced using the present experimentalPK values and theoreticalPL/PK ratios. The dependence ofPK values on theQ value is also tested.

Gamma-ray energies from the decay of 152Eu

Gamma-ray energies of 152Eu were measured with the uncertainties of 1.1–7.3 eV in the region of 290–720 keV using Ge spectrometers. To determine the 719 keV γ-ray energy of 152Eu, we measured the 125 and 592 keV cascade γ-ray energies of 185Os which provide the 717 keV cross-over γ-ray energy. Seven γ-ray energies of 152Eu in the region of 770–1400 keV were obtained from the sum of the cascade γ-ray energies.

Application of the sum peak method to study changes in the K-capture probability to the 1086 keV level and perturbed angular correlation parameters in the decay of152Eu

The sum peak method has been applied to electron capture probability changes to the 1086 keV level in the decay of152Eu in the different environments, e.g. ethylenediaminetetraacetic acid (EDTA), bovine serum albumin (BSA) and hydrochloric acid (HCl). An attempt is also made to determine the effect of chemical environment on the directional correlation coefficient of the 1409–122 keV γ-γ cascade in152Eu →152Sm decay. A change of G22 is found in the different chemical forms.

On the newly proposed levels in152Gd and152Sm

It is shown that there is no evidence for the existence of levels at 1312.41, 1485.67 and 1698.34 keV in152Gd and at 1436.65 and 1681.56 keV in152Sm, which were recently claimed to be observed in the decay of152Eu(3−, 15 y).

Levels in152Gd and152Sm populated by the decay of152Eu

The energy level schemes of152Gd and152Sm have been established on the basis of singlesγ-spectra, andγ- γ coincidence measurements. Ge(Li) detectors were used to study the gamma spectra produced in the EC/β+ and β− decays of152Eu to152Sm and152Gd, respectively. Thirteen new transitions are reported and data from eleven coincidence gates enabled five new levels to be suggested. Relative intensities and logf t values were calculated and spin/parities deduced. Comparisons are made with new predictions of the Interacting Boson Model.

Precision measurements of gamma-ray energies from 13.3 a 152Eu decay

The energies of 29 γ rays from the decay of 152Eu have been determined in order to provide calibration energies for Ge γ-ray spectrometers. Particular emphasis is placed on those γ transitions resulting from the decay of the 152Sm 1530 keV level. A least-squares adjustment to these 152Sm γ transitions results in a set of recommended calibration lines.

Precise conversion electron intensities of 152Eu decay for detector calibration purposes

A double focusing electron spectrometer has been used to determine precise relative intensities of internal conversion electron (ICE) lines following the decay of 152Eu in order to produce a suitable standard for solid state electron detectors. Intensities of 21 electron lines are given in the energy range 198 keV to 1.361 MeV with a precision close to 3.5%. For the 02+−01+ E0 transition in 152Gd, a precise energy of 615.406(11) keV has been established and an X-value of 0.047(5) was derived.

K/LM+ internal-conversion ratios for pure E2 transitions in the decays of 152Eu and 192Ir

Measurements have been made with a magnetic β-ray spectrometer in order to determine the internal-conversion ratio R = K/LM+ for pure E2 transitions of 244.7 and 344.3 keV in the decay of 152Eu and of 205.8 and 316.5 keV in the decay of 192Ir. The results from several experimental runs for each transition are respectively, R = 2.92 ± 0.05, 3.43 ± 0.05, 1.05 ± 0.04 and 1.71 ± 0.05. A comparison has been made with previously published results as well as with theoretical values deduced for pure E2 multipolarity from the most recent tabulations of internal-conversion coefficients.

The radioactive decay of152Eu

Gamma-rays associated with the decay of152Eu to152Sm and152Gd have been investigated using Ge(Li) and hyper pure Ge spectrometers. The gamma-gamma coincidence studies have been performed using a NaI(Tl)−Ge(Li) coincidence spectrometer.

Precision measurements of gamma-ray intensities. II. 152Eu, 154Eu and 192Ir

Relative intensities of gamma rays in the decay of 152Eu, 154Eu and 192Ir were measured precisely with a calibrated Ge(Li) detector. Errors of relative intensities for strong gamma rays are 0.3–0.5%. These multi-gamma-ray sources are useful for the calibration of the Ge(Li) detector. Gamma-ray intensities per decay of 192Ir were derived from the relative intensities.

X-ray emission probabilities per decay of 152Eu

X-ray emission probabilities p per decay of 152Eu were determined by means of an activity-calibrated source and a high purity germanium detector. The results p(Sm−K α )=0.591±0.012 and p(Sm−K β )=0.149±0.003 are in good agreement with the values expected according to theory.

Internal conversion electron measurements following the decay of 152Eu

Relative intensities of internal conversion electron lines from the decay of 152Eu are measured accurately with a Si(Li) detector. The results thus obtained are presented, clarifying many discrepancies of previous works.

Relative efficiency calibration of Ge(Li) detector in low energy region

The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of152Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of241Am,57Co,203Hg,137Cs,133Ba,75Se,169Yb and192Ir.

OnE0 transitions in the decay of152Eu m (9.3 h)

The conversion electron spectrum of the decay of152Eu m (9.3 h) has been specially investigated forE0 transitions with the aid of a magnetic spectrometer and coincidence techniques. Besides the knownE0 transitions of 685 keV in152Sm and 615 keV in152Gd two further pureE0 transitions of 432 keV and 1048 keV have been observed. It is shown that theseE0 transitions are identical with those observed previously in the decay of152Tb. NoE0 transitions could be found from a 0+ state of 1083 keV in152Sm. The measured intensities together with the gamma spectrum measured by Barretteet al. give a consistent decay scheme of152Eu m . Furthermore the half-life of the 0+ level at 615 keV in152Gd was measured using the method of “delayed coincidences”. The result was (0.2≦t 1/2≦2.1)×10−10 s. From this theE0 transition probability for the level was derived as (0.3≦W K (E0)≦3.7)× 109 s−1 and theρ-value as 0.10≦¦ρ¦≦0.36. The results are discussed within the framework of the collective model.

Mono-energetic positon emission in the decay of 152Eu

The mono-energetic positon emission of the 1409 keV El transition in 152Sm has been measured using a Siegbahn-Slätis intermediate-image spectrometer. By comparing the intensity of the positon peak with that of the internal conversion line of the same transition the branching ratio for this process has been determined as (2.5±1.0) × 10 −7 positon per gamma transition, in reasonable agreement with that reported by Perdrisat et al. The mean life of the 1531 keV level of 152Sm has been estimated to be τ = 5.7 × 10 −15 sec. From our experimental value and relative transition intensities it is found that the 1409 keV El transition is retarded, when compared with the single proton transition probability, by a factor of at least about 60.

Decay of152Eu and the unified nuclear model

The radiations from152Eu (t1/2=13 yrs) were investigated using an intermediate image spectrometer, a magnetic thin lens spectrometer and a coincidence scintillation spectrometer. Three β--groups are present with end-points (1450±25), (1040 ±20), (710±20)keV; the highest energy group exhibits an α-shape. γ-ray investigations showed that the following γ-rays are present: 101 (5), 121 (88), 244 (30), 315 (4), 344 (100), 410 (9), 442 (4), 710 (13), 770 (77), 888 (14), 970 (89), 1090 (96), 1127 (96) and 1410 (135) keV.K-conversion coefficients were estimated for most of these transitions and multipole orders were assigned. X-ray-γ, γ-γ and β-γ coincidence experiments allow us to construct the decay scheme of152Eu. The difference in level structure in152Sm (N=90) and152Gd (N =88) is evident from the experimental results. The first three excited states at 121, 365 and 807 keV in152Sm are identified as the three members of the ground state rotational band (K=0) ; the levels at 1090 and 1248 keV havingI= 2 +, and 3 + respectively are shown to be the quadrupole γ-vibrational states corresponding to K=2. The highest excited state in152Sm is at 1417 keV and is most likely fed entirely byL-capture; this is the only odd-parity state in152Sm having the character I=1-. The levels in152Gd at 344 and 754 keV both with I=2 +, reached by β--decay, are characteristic of the collective vibrations of the electric quadrupole type about a spherical equilibrium shape. The level at 1114keV in152Gd has the character I=— and is interpreted as due to the octupole vibrations. The ground state of152Eu has been assigned the spin I=4 -; the branching ratios and the transition probabilities for the β--groups and electron capture transitions have been calculated. The experimental results are consistent with the predictions of the Unified Nuclear Model.

Slow Neutron-induced Activities in Europium and Samarium

The activities produced by the neutron irradiation of europium and samarium have been investigated by means of a thin lens type β-ray spectrometer and by absorption and coincidence methods. The 9.2-hour activity in europium is due to the dual decay of 152Eu by β-emission and by K capture. The long period activity is due to both 152Eu and 154Eu, and again both β- emission and K capture are present. This long period K capture is due to 152Eu, and the β- emission is possibly due to both 152Eu and 154Eu. The energies of the emitted radiations are discussed and possible decay schemes proposed. The 47-hour activity induced in samarium is due to the β- decay of 153Sm, and measurement of the energies of the emitted radiations has been made.