K, L and M electron directional correlations in Te

Directional correlations of the cascade in ¹²³Te involving K, L and M electrons from the 89 keV M4 transition have been measured in order to determine the δ(E2/M1) value for the 159 keV transition. The result agrees with that from older correlation measurements, but is in conflict with values derived from Coulomb excitation and lifetime measurements as well as from L subshell ratios.     

Conversion electrons in the decay of191Os

Internal conversion electrons in the decay of¹⁹¹Os have been measured with a 30 cm double focusing spectrometer. The transition energies of (129.27±0·07) keV, 82.5 keV, (46.90±±0.06) keV and (41.76±0.02) keV are given together with the corresponding internal conversion line intensities. It was found that the mixture of the 129 keV transition was 87% M1+13% E2. The previously proposed decay scheme is supplemented by the 46.90 keV transition.The authors would like to thank to M. Vobecký and A. Matalka for preparing the electrodeposited sources.     

Decay properties of76m Br

The remeasured half-life of^76m Br was found to be 1.31±0.02s.γ-ray and conversion electron measurements gave for two cascading transition energy values 57.11±0.02 and 45.48±0.02 keV with multipolaritiesM2 and M1, respectively. The 4⁺ isomeric state at 102.59±0.04 keV is placed in the⁷⁶Br level scheme. The intensity of the cross-over transition is less than 0.8% of isomeric decays.     

Decay of 17-min, 19/2−129mSb

A 17.1min, 19/2^? isomer has been established in¹²⁹Sb at 1851 keV. It is fed by levels populated in the decay of the 6.2min, 11/2^?129Sn isomer. This isomer decays by an M4, 723keV internal transition and by β^? decay to levels in¹²⁹Te. The 723keV transition is 20 times slower than 11/2^?→3/2⁺ M4 transitions in the adjacent odd-N nuclides and is 10 times faster than the M4 transition from the 19/2^? isomer in¹³⁵Cs. A partial level scheme for the decay of the 11/2^?,¹²⁹Sn isomer is given showing levels that populate the 19/2^? isomer along with a partial level scheme for¹²⁹ Te.     

The decay of Cs

In a study of the level scheme of ¹³¹Cs, we have measured the γ-γ and the ce-γ directional correlations of the 496-123.7 keV and 486-133.5 keV cascades. The linear polarization at φ=90° was measured for the 496-123.7 keV and 486-133.5 keV cascades. The L-subshell ratios for the 123.7 keV transition were determined. The g-factor of the 133.5 keV level and the half-lives of the 78.7, 123.7, 133.5 and 216 keV levels were re-investigated. The spin and parity assignments derived for the 620, 133.5 and 123.7 keV levels are , respectively. The 620, 496, 486, 133.5 and 123.7 keV transitions are found to be of pure E2, pure M1, pure E2, (M1+(22±2)%E2) and pure E2 multipolarity, respectively. An upper limit of 192 ps for the half-life of the 216 keV level is obtained. The results are compared with theoretical estimates from the calculations of Kisslinger and Sorensen, of Freed and of Freed and Miles.     

Der Zerfall des 4,4 min-Rh104m

The decay of the 4.4 min-Rh^104m has been investigated by observing coincidences between conversion electrons and gamma quanta. The decay by a 77 keV?52 keV cascade has been confirmed. In addition, a highly converted (31±2) keV transition in coincidence with the known 97 keV gamma ray has been found. The multipole order of this transition has been determined asM3. The intensity of the 97 keV?31 keV cascade has been measured as 3.3 % of the intensity of the 77 keV?52 keV cascade. An indication of a 45 keV transition from the 97 keV level to the 52 keV level has been found with an intensity of at most 0.1 % of the intensity of the 77 keV?52 keV cascade.     

Measurements of someK-internal conversion coefficients near threshold

TheK-internal conversion coefficients have been measured by the XPG technique for a number of low energyγ-ray transitions whose energies do not exceed theK-binding energies by more than 4 keV. Using Si(Li) detectors in singles and coincidence arrangements, the following results were obtained: 63.1 keV El in¹⁶⁹Tm(α_K=1.02±0.15), 72.0 keV E1 in¹⁸⁷Re (0.75±0.05), 57.8 keV M1 in¹⁶²Ho (11.42±0.67), 56.6 keV M1 in¹⁶⁴Ho (12.04±0.70), and 67.1 keV M1 in¹⁷⁴Lu(10.25±0.58). The experimental results are compared with the theoretical calculations which include transition energies down to 1 keV above threshold.     

Alpha decay of Cm

An enriched sample of ²⁴⁷Cm (99.4 %) has been used to investigate the -decay scheme of ²⁴⁷Cm. Seven -groups with energies and intensities 5.265 (13.8 %), 5.210 (5.7 %), 5.145 (1.2 %), 4.983 (2.0 %), 4.941 (1.6 %), 4.868 (71.0 %) and 4.818 (4.7 %) were observed. Gamma-singles and γ coincidence spectra showed the presence of 278.0, 287.5, 346.0 and 402.4 keV γ-rays. A two-parameter coincidence experiment established that the sources of the 402.4 and the 287.5 keV γ-rays were 4.868 and 4.983 MeV -groups, respectively. The multipolarity of the 287.5 keV transition was found to be M1. The K conversion coefficient of the 402.4 keV γ-ray indicates an E1 multipolarity for this transition. The levels at 287.5 and 402.4 keV have been assigned to the and Nilsson states, respectively. The half-life of ²⁴⁷Cm was found to be (1.56±0.05) ×10⁷ y from the pulse analysis and mass spectrometric analysis of the sample.     

Gamma transitions in the decay of195mPt

The gamma transitions in the decay of^195mPt were investigated by the use of high resolution double focusing beta-ray spectrometer. Conversion electrons were observed for transition of energy 79.94±0.32 keV and ascribed for the first time to the decay of 4.2 d^195mPt. This confirmed that the 209 keV level decays either by the 208.81 keV transition (98%) or by a 79.94 keV–128.51 keV cascade (2%). The multipolarity assignment for each transition in¹⁹⁵Pt was obtained by comparing the measured conversion line intensity ratios with the theoretical line intensity ratios ofSliv andBand. Two gamma transitions of nearly equal energy 129 and 130 keV could be detected, the first found to be pureE2 transition while the latter hasM4 character. The mixing ratio of some gamma-rays have been determined and some discrepancies were found. The data were discussed on the light of Coulomb excitation results.     

70As(β++EC)衰变到70Ge的低自旋激发态(英文)

通过70As的放射性衰变研究了70Ge的激发态,新发现能量为1 036.99,1 196.66,1 539.29和2 531.7 keV的四条新γ射线,重新确认了2 219.34 keV γ射线的跃迁位置,新确认496.74,1 295.24和1 417.24 keV这三条γ射线首次放入衰变纲图,本工作证实了1 881.67,2 325.42和2 424.41 keV γ射线的跃迁位置,建议了能量为4 243.10和5 265.81 keV的两个新能级,建立了新的衰变纲图,基于比较半衰期和γ跃迁分支比建议了一些能级的自旋-宇称。The excited states of the 70Ge nucleus are investigated in radioactive decay of the 70As. Four new transitions with 1 036.99, 1 196.66, 1 539.29 and 2 531.7 keV are found for the first time. The position of 2 219.34 keV transition are reassigned, the transition positions of 496.74, 1 295.24 and 1 417.24 keV γ-rays are assigned for the first time, and the placements of 1 881.67, 2 325.42 and 2 424.41 keV γ-rays are confirmed in the present work. Two new levels, at 4 243.10 and 5 265.81 keV excitation energy, respectively, are proposed. The decay scheme is established and for a number of levels spin-parity assignments are suggested on the basis of logft values and γ-branching ratios.     

Largeurs de transitions gamma du niveau à 2788 keV de 21Ne

Branching ratio, angular correlation and lifetime measurements are reported for the 2788 keV level of ²¹Ne. The results for the 2788 → 350 keV branch are consistent with a pure M2 transition of strength 0.45 ±0.04 W.u.     

Conversion-electron-gamma and gamma-gamma directional angular correlations in 160Dy

Gamma-gamma and conversion-electron-gamma angular correlations in ¹⁶⁰Dy have been measured for the 298 keV–966 keV and 298 keV–879 keV cascades. Particle parameters of the 966 keV E2 transition were determined to be b₂(E2; e_K) = +1.23±0.08 and b₂(E2; e_{ΣL + ΣM) = +1.27±0.23}. The multipole mixing ratio for the 298 keV radiation was determined to be δ(M2/E1) = +0.04±0.01 and we have confirmed the value δ(E2/M1) = ?13±2 for the 879 keV. The E0–E2 mixture parameter for the 879 keV transition was determined as q_K = ?0.03±0.09 assuming penetration effects to be negligible.     

Calibration of the isomer shift of125Te from internal conversion and mössbauer measurement

Radioactive¹²⁵I was ion-implanted into 7 different metal matrices. Al, Au, In, Pt, Sn, Te and Zn, and internal conversion and Mössbauer spectra associated with the 35.46 keV M1 transition of¹²⁵Te were measured for the same samples. A value R/R=(0.853±0.115)×10^–4 was derived for the relative difference of the nuclear charge radius for the 35.46 keV M1 transition of¹²⁵Te.     

Decay of Cs134m

The decay of the isomeric state of Cs¹³⁴ was studied. The decay half-timeT _1/2=2·93±0·05 hours was determined. From measurements carried out by means of a spectrometer with short lens, scintillation measurements and chemical separations, the non-existence of the weak decay of this state was proved, contrary to statements found previously in the literature (maximum possible intensity 0·02%, compared to the value of 1% found in the literature). The spectrum of conversion electrons was measured by a double-focusing spectrometer, and the following transition energies were determined: 127·3±0·3 keV (E3) and 138·4±0·4 keV (M4) (K:L:M+N is 92 100 27 for the 127·3 keV transition, and 206 100 31 for the 138·4 keV transition). The conversion coefficient of the 127 keV transition was measured, resulting in a value of _k =2·55±±0·4. The ratio of transition intensities isI ₁₃₈ I ₁₂₇=5·7 1000.     

A 480 ms isomeric 29/2−-state of the(p_{1/2}^{ - 2} )_{0^ + } f_{5/2}^{ - 1} (i_{13/2}^{ - 2} )_{12^ + } configuration in203Pb

A new, 480 ms, 29/2^? isomeric level has been found in²⁰³Pb at an excitation energy of 2950.1 keV by bombarding²⁰⁴Hg with α-particles in the energy range 45–55 MeV using the Stockholm 225-cm cyclotron. This 29/2^? state is suggested to be mainly due to the configuration (p ₁ ^2/?2 f ₅ ^2/?1 i ₁₃ ^2/?2 )₁₂. The 29/2^? state decays predominantly by a 153.4 keV M2 transition to a 23/2^? level and by a 1027.5 keV M4 transition to a 21/2⁺ level, followed by two E2 transitions of energies 258.6 keV and 838.7 keV, respectively, to the previously known 13/2⁺, 6.4 s isomeric level. The decay scheme of the 29/2^? isomeric state is based on experimental information obtained from total and delayedγ-ray intensities,γγ-coincidences, excitation functions, lifetime and delayed conversion electron measurements. The presence of the 29/2^? level confirms an essential and expected feature of the shell model for five neutron holes added to the²⁰⁸Pb-core.     

Determination of relative intensities of M internal conversion lines in pure E2 transitions

Accurate measurements have been performed on the relative intensities of the M internal conversion lines of three pure E2 transitions in nuclei in the rare-earth region. The results are compared with theoretical values obtained from the calculations by Bhalla and by Hager and Seltzer. Discrepancies of about 6% between experiment and theory are reported for the M_I/M_II and M_I/M_III ratios of the 80.57 keV transition in ¹⁶⁶Er. The M_II/M_III ratios of the 84.26 keV transition in ¹⁷⁰Yb and of the 100.09 keV transition in ¹⁸²W are significantly lower than predicted by theory.     

A new level at 192.5 keV in Ge

In the experiments on ⁷⁴Ge(d, pγ)⁷⁵Ge, a 52.5±0.1 keV γ-ray was found in ⁷⁵Ge with a half-life of 216±5 ns. From the analysis of the γ-ray spectra the conversion coefficient of the 52.5 keV γ-ray was determined. Then, a new level of is confirmed to exist at 192.5 keV. The reduced transition probabilities of the 52.5 keV transition are deduced to be (6.9^+5.6 _−2.1) × 10⁻⁵ for B(M1) and 31⁺³ ₋₂ for B(E2) in Weisskopf units.     

Position — Sensitive single-wire proportional counter for conversion electron Mössbauer spectroscopy

A position-sensitive single-wire proportional counter for the INS 2 air-core spectrometer has been improved to take conversion electron Mössbauer spectrum as a function of electron energy with a multichannel mode. The position resolution at 13.6 keV was found to become 1.6 mm with the counter gas pressure of 320 Torr. The position resolution was obtained as a function of energy between 7 and 60 keV for gas pressure of 40 Torr, 160 Torr and 320 Torr. The L, M and N conversion electron spectrum of the 14.4 keV transition in⁵⁷Fe was taken with the present system. Overall momentum resolution was found to be 0.23% for the L₁-line and 0.19% for the M₁ line.     

The electron capture decay of 195Au

The decay of ¹⁹⁵Au has been investigated by means of a 4π internal source scintillation spectrometer and a Ge(Li) detector. Electron capture branching ratios and several L/K and M+…/L capture ratios have been measured. The atomic electron capture transition energy and the cross-over decay probability of the 130 keV state have been calculated.