H.J. van den Bold

The decay of the nuclides 75Se and 75Ge

Synopsis Gamma transitions in the decay of the nuclides 75Se and 75Ge have been investigated by scintillation spectroscopy. Single spectra and coincidence spectra were found to conform with the level schemes constructed by previous authors. Directional correlations of five γ cascades have been measured. Polarization correlation measurements were performed on the 121 keV — 280 keV and 136 keV — 265 keV γ cascades. The following spins and parities have been assigned to levels in 75As: ground state 3/2−, 199 keV ½−, 265 keV 3/2−, 280 keV 5/2t-, 304 keV 9/2+, 401 keV 5/2+.

The decay of 77Ge and 77Gem

Gamma rays in the decay of 77Ge and 77Gem were investigated with scintillation spectrometers using γ-γ coincidence, sum-coincidence and γ-γ angular correlation techniques. About fifty γ transitions were identified. A decay scheme is proposed including the following 77As levels: 215±2 (32−), 263±2 (52−), (325±15), 473±3 (92+), 632±2 (52+), 755±4, (925±15), 1195±3 (52), 1280±8, 1457±6, 1557±4, 1700±15, 2001±6, 2109±10, 2232±9, 2347±, (2445±15) and 2565±25 keV. Six of these levels have not been reported before. The 77Gem half-life is 59±2 s.

Continuous and discrete gamma-radiation in the decay of 103Pd

Synopsis The continuous γ-ray spectrum (internal bremsstrahlung) and the discrete γ-rays resulting from the decay of 103Pd by electron capture have been investigated with a scintillation spectrometer. Weak discrete γ-rays have been found with the following energies and intensities: 503 ± 8 keV (0.11 ± 0.02‰), 367 ± 6 keV (0.60 ± 0.07‰), 305 ± 8 keV (0.11 ± ± 0.03‰) and (262 ± 15) keV (0.04 ± 0.02‰). The continuous spectrum has been observed, but accurate determinations of its endpoint, intensity and shape were made difficult by the presence of the discrete γ-rays. From an analysis of observed ft-values the 103Pd spin and parity can be determined as J= 5 2 + and the 103Pd-103Rh mass difference as (557−12+27) keV.

The decay of 115Cdm

Synopsis In the decay of 115Cdm (43 d) several new, very weak, γ transitions have been observed in scintillation single spectra and/or coincidence spectra, with the following energies and intensities (in percents of the intensity of the 935 keV γ ray): 130 ± 5 (0.07), 162 ± 3 (1.3), (206 ± 6) (0.15), 292 ± 5 (0.2), 1130 ± 5 (5.2), and 1420 ± 15 keV (2.0). These γ rays fit into the known 115In level scheme if a new level is assumed at Ex = 1129 keV, excited through a 0.07% β- transition. The γ-γ angular correlation has been measured of the 485–935 keV cascade. From this measurement and from considerations on γ-ray intensities and β-ray ft values, spin and parity assignments of 7/2+, (13/2)+, (ll/2)+, and 9/2+ are made to the 115In levels at 935, 1129, 1290, and 1420 keV, respectively. These levels can be regarded as generated by the removal of a g9/s. proton from 116Sn in its first excited state (Jπ = 2+). From Lawson and Uretskys centre-of-gravity rule the excitation energy is estimated of the missing 5/2+ member of this quintuplet.

Scintillation spectrometry study of the 73Se isomeric pair

The position and the gamma ray spectra of the two 73Se isomers have been studied with a scintillation spectrometer. No new gamma rays have been observed in the decay of the (7.1 ± 0.2) hour activity. The (42 ± 3) min activity shows a position group of (1.72 ± 0.10) MeV and the three gamma rays of 88, 251 and 580 keV and possibly one of 1080 keV. The relative position of the two isomers cannot be deduced from the results of these measurements; no isomeric transition has been identified with certainty. If an isomeric transition occurs, it might be associated with the gamma ray of 88 keV which then should be of M3 or E3 character, but this interpretation is not very attractive in view of shell model predictions for 73Se.

GAMMA RADIATION IN THE DECAY OF 67Ga

Synopsis The level scheme of 67Zn has been investigated by scintillation coincidence spectrometry. Angular correlation measurements of the 206 keV – 182 keV and 485 keV − 296 keV gamma cascades result in anisotropies of − 0.216 ± 0.008 and +0.27 ± 0.05. The following spins have been allocated to the levels of 67Zn: ground state 5/2, 92 keV 3/2, 182 keV 5/2, 388 keV 3/2 and 870 keV 3/2. Evidence has been found for the existence of another level at 595 ± 10 keV, for which a spin of 5/2 is suggested. By delayed coincidences a value of 9.3 ± 0.2 μsec has been found for the half-life of the 92 keV metastable level in 67Zn.

Optical investigation of an atomic hydrogen flame

Summary A flame of atomic hydrogen has been investigated for the purpose of testing its possibilities regarding the investigation of thermic emission and absorption of radiation by gases (§ 1). The apparatus (§ 2) is sketched in fig. 1. The optical arrangement for the measurement of temperatures by means of line reversal is given in fig. 2 and described in § 3. The general appearance and the flame properties are described in § 4, where amongst other things it is pointed out that the discharge is periodic. The distribution of the temperature in a horizontal section of the flame (§ 5) is represented in fig. 3, while fig. 4 and the table give the vertical course of the temperature as well as its dependance on the arc current etc. Simultaneous reversal measurement of several spectral lines was found to lead to the same reversal temperatures (§ 7), the conclusion being that the population of the respective upper levels complies with the Boltzmann formula. From the combined results we may conclude that the flame of atomic hydrogen can be used with advantage for the determination of transition probabilities of spectral lines with excitation energy ≤ 6 eV. For a number of details, see the original publication 1).