Kazuo Hisatake

A retarding-grid electron spectrometer for Mössbauer spectroscopy

Abstract A new retarding-grid electron spectrometer for conversion electron Mossbauer spectroscopy has been constructed. The structure and performance of the spectrometer are described in detail. The response functions for various settings of energy resolution have been determined using the energy spectrum of a very thin 57Co source. The best energy resolution obtained is 0.3% at 7.3 keV with a detection efficiency of 1.2% 4π .

Level structure of 105Pd studied from the decay of 105Ag

Abstract The level structure of 105 Pd was investigated by measuring internal conversion electrons following the decay of 105 Ag with a 2 π air core β-ray spectrometer. Seventy-three conversion lines including five new transitions and three new conversion lines were observed. The 443 and 644 keV transitions were revealed to be doublets. The L-subshell ratios of the 64, 90, 155, 183, 280, 319, 344, 392 and 443 keV transitions were measured with the resolution between 0.024 and 0.082 %, and the multipolarities and the mixing ratios of these transitions were determined. The level energies and the spin-parities of 105 Pd are as follows: 0[ 5 2 + ], 280.51[ 3 2 + ], 306.25 [ 7 2 + ] 319.18[ 5 2 + ], 344.52[ 1 2 + ], 442.23[ 7 2 + ( 5 2 + )], 489.11[ 11 2 − ], 560.75[ 1 650.69[ 3 2 + ], 673.18[ 1 2 + , ( 3 2 + , 5 2 + )], 727.17[ 5 2 + ], 782.1 [ 9 2 keV [ 3 2 − ] . The level structure of 105 Pd is discussed in terms of the core excitation and quasiparticle excitation.

Half-Life Measurements in Rh101 and Rh102m

The half-lives of Rh 101 and Rh 102m have been investigated by measuring the internal conversion electrons with a magnetic beta-ray spectrometer. The half-life of Rh 101 and that of Rh 102m are determined to be (3.0±0.4) y and (2.1±0.9) y , respectively.The half-lives of Rh 101 and Rh 102m have been investigated by measuring the internal conversion electrons with a magnetic beta-ray spectrometer. The half-life of Rh 101 and that of Rh 102m are determined to be (3.0±0.4) y and (2.1±0.9) y , respectively.

The decay of 2.2 h 138Pr and excited states in 138Ce

Abstract The decay of 2.2 h 138 Pr was studied with NaI(Tl) scintillation spectrometers and a magnetic beta-ray spectrometer. The energies (MeV) and relative intensities (indicated in parentheses) of the observed gamma rays are 0.298(77), 0.40(9), 0.51(61) (annihilation radiation), 0.55(≈ 5), 0.788(100), 1.035(100), 1.2(≈ 1) and 1.83(≈ 0.4). The 0.298 MeV transition is determined to be of E3 from the K/LM ratio and the K conversion coefficient, and the multipolarity of the 1.035 MeV transition is determined to be of E2 from the K conversion coefficient. From gamma-gamma angular correlation and internal conversion measurements the spins and parities of the second and the third levels of 138 Ce are determined to be 1.823(4 + ) and 2.121(7 − ), respectively. A new level at 2.22 MeV is proposed from gamma-gamma coincidences. The 138 Pr positons were found mainly (92% per decay including electron capture) to feed the 2.121 MeV state with the maximam energy of 1.65±0.02 MeV. Thus the log ft value is obtained to be 5.7±0.1. The spin and parity of the 2.2 h 138 Pr, which are assigned to be 7 − , 8 − or 6 − , are discussed. The 7 − → 4 + E3 transition is also discussed.

Depth selective conversion electron Mössbauer spectroscopy by use of a proportional counter

The depth selectivity of conversion electron Mössbauer spectroscopy by use of a proportional counter was studied in detail. For this purpose the pulse-height spectrum of conversion and Auger electrons emitted from a57Fe absorber was measured at the resonance Doppler velocity. From the spectrum it is found that the energy settings of 2–5 keV, 6–9 keV and 11–14 keV are suitable for depth selective analysis.

Penetration Effects for Internal Conversions in the Odd-Mass Isotopes of La and Cs

Penetration parameters λ are determined by using internal conversion intensities and coefficients for low energy hindered M1 transitions of 131 Cs, 135 La, 137 La and 139 La together with E2/M1 mixing ratios δ 2 . The results are; λ(86.9, 135 La)=14.5±5.5, λ(10.5, 137 La)=10±5, λ(166, 139 La)=3.6±1.8 and λ(92.3, 131 Cs)=4±4, where numbers in parentheses are transition energies in keV.

Energy distributions of 7.3 keV electrons passing through iron films for depth-selective Mössbauer spectroscopy

Abstract The energy spectra of 7.3 keV electrons passing through iron films were measured with a high resolution electron spectrometer by use of a thin 57Co source. The energy resolution of the spectrometer was set for 1.3% at 7.3 keV. The thicknesses of iron films for electron scatterers were 63, 121, 175, 279 and 385 A. From the measured energy spectra we deduced the energy distributions for a monolayer source. The method of analysis is described in detail. The present energy distributions are in fair agreement with those of the Monte Carlo calculation of Liljequist et al. The weight coefficients for the depth-selective conversion electron Mossbauer spectroscopy are presented for energy resolutions of 1, 2 and 3%.

Determination of 27Al(p, α)24Mg reaction times with the blocking effect

Abstract The reaction times for the 27Al(p, α)24Mg reaction at four resonances were measured by the blocking effect technique. A ≈ 1 mm thick A1 single crystal was used as a target. By comparing the reduction in the area of the {111} planar blocking dip with the theoretical value, the reaction times at the Ep = 633, 731, 937 and 1183 keV resonances were determined to be 135±20, 59±8, 11±8 and ≦ 14 as, respectively. These reaction times are consistent with previously reported resonance widths.

The 0+ excited state of Ce140 studied by the decay of Pr140

Abstract The 1.902 MeV 0 + state in Ce 140 was studied by the decay of Pr 140 . First, the 0.306 MeV gamma ray, which was assigned to be the transition from the1.902 MeV 0 + (denoted by 0 + ′) to the 1.596 MeV 2 + states, was found in the coincidence spectrum gated by the 1.596 MeV gamma ray. The gamma-gamma angular correlation for the 0.306—1.596 MeV cascade was found to be consistent with the (0-2-0) spin sequence. The 0.306, 1.596 and 1.902 MeV internal conversion electrons were observed using a sector-type double focussing spectrometer. The branching ratio of the (0 + ′ → 0 + ) to the (0 + ′ → 2 + ) transition was obtained to be 1.13±0.12. The strength parameter ϱ is discussed assuming the partial life of the (0 + ′ → 2 + ) transition. The log ft values from Pr 140 to the ground, the first 2 + and the second 0 + excited states of Ce 140 were determined to be 4.4, 6.0 and 5.9, respectively. From the log ft values the spin and parity of the ground state of Pr 140 is assigned to be 1 + .

Determination of surface-spin orientation of rare-earth iron garnet films by the Mössbauer spectroscopy

Abstract Spin orientations and hyperfine-field distributions of rare-earth iron garnet fils were dewtermined as a function of depth by means of energy-resolved conversion-electron Mossbauer spectroscopy. The spin-tilt from the surface normal was found to be (20 ± 5)dg less than 500 A in depth.