Gamma Coincidence Measurements Research Articles

Nuclear spectroscopy in63Zn: states below 1.5 MeV

The electromagnetic decay transitions of the low-lying negative parity states below 1.5 MeV in excitation energy in 63Zn have been studied using the 60Ni( alpha ,n gamma )63Zn reaction (Q value=-7.905 MeV), at incident beam energies of 8-16 MeV. Spins and parities of the levels, together with the branching and mixing ratios of their gamma ray decays have been obtained from excitation functions, gamma - gamma coincidence, angular distribution and linear polarisation measurements with the compound-nucleus statistical model.

The decay of75Kr

The decay of the isotope75Kr (T1/2=4.5 ±0.3 m) has been studied using mass separated sources produced at the ISOLDE facility at CERN. A decay scheme is proposed based on gamma, positon, and conversion electron singles and coincidence measurements. The total decay energy was measured to be QEC=4.4 ± 0.2 MeV. The resulting spin-parity assignments and the absence of a 9/2+ isomeric state in75Br are discussed.

Ge(Li)-Ge(Li) coincidence measurements in 132Xe

Gamma-- gamma coincidence measurements were carried out on the decay of / sup 132/I with two Ge(Li) detectors and a two-parameter system. Several new transitions were observed. From these results, 18 new levels at 2167.3, 2187.4, 2303.6, 2916.9, 2935.6, /sup 132/Xe level scheme which incorporates 113 of the 119 definitely established gamma rays in this decay and can incorporate 5 of 16 additional tentatively reported transitions. (FR)

Beta decay of 187W

Coincidence studies have established in the decay scheme of,187W the existence of transitions of energy 7, 36, 77, 455, 589, and 639 keV with intensities of 3.0 ± 0.5%, 0.50 ± 0.06%, 0.31 ± 0.07%, 0.05 ± 0.02%, 0.14 ± 0.04%, and 0.05 ± 0.02% respectively as well as yielding the absolute intensities of the well-known transitions in 187Re. In addition the beta–gamma coincidence measurements have shown that (1) a first-forbidden unique transition feeds the first-excited state of 187Re, (2) there is at most a very weak beta transition to the level at 512 keV, (3) there is no inner beta group of about 300 keV end-point energy and intensity 8% as indicated by several earlier investigations, and (4) the decay energy of 187W to 187Re is 1311 ± 2 keV. The relevance of these observations to the structure of 187Re is discussed.

High energy levels of 144Nd excited in the decay of 144Pm

Gamma–gamma coincidence measurements, carried out with a 7.6 cm × 7.6 cm NaI(Tl) crystal and a 30 cm3 Ge–Li detector, have been performed to look for excited states in 144Nd higher than the known level at 1789 keV. These measurements definitely establish the existence of a level at 2093.11 keV and suggest the placing of another level at 2204.74 keV. Furthermore, an E3 transition deexciting the 1510.14-keV level seems to be present.

Allowed K-capture to position emission ratios in the decays of 48V and 52Mn

Branching ratios of K-capture to position emission probabilities have been measured for the allowed beta transitions in 48V and 52Mn by triple-gamma coincidence experiments with NaI(Tl) counters and also by beta gamma coincidence measurements with a proportional counter-NaI(Tl) crystal arrangement. The results K/ β + = 0.69±0.03 for 48V and K/ β + = 1.72±0.11 for 52Mn are in good agreement with theoretical predictions.

DIRECTIONAL CORRELATIONS IN 127I

Gamma–gamma coincidence measurements on the decay of 9.3-hour 127Te to 127I form the basis of the decay scheme presented, which confirms the accepted decay sequence. Directional correlation measurements have been made on the 215–203 keV and 360–58 keV cascades. The respective correlation functions are:[Formula: see text]The directional correlation results have been interpreted in terms of the accepted spin sequence, and limits of multipole mixtures are presented. A short discussion of the collective properties of the levels is presented.

The penetration matrix element of the 279 keV transition in Tl 203

The penetration matrix elements (PME) that express the conversion probability within the nucleus are obtained from dynamic effects of the finite size of the nucleus in measurements of internal conversion coefficierts and conversion electron directional correlation patterns. Electron- gamma coincidence measurements were made for the 279-kev transition in 203Tl, which was obtalned by electron capture decay of 203Pb. (R.E.U.)

Energy levels of Te 125

The energy levels of Te 125 have been studied by detailed gamma gamma coincidence measurements. Two new weak gamma transitions of energies 80 ± 5 keV and 120 ± 5 keV have been observed in coincidence with the 176 keV gamma transition. A new energy level has been introduced at 401 keV. There is evidence of a weak gamma transition of 62 keV between levels at 524 keV and 462 keV.

Three-particle excitation in Lu 177

Quantitative e- gamma coincidence measurements showed that all strong transitions were coincident with 3 to 5 others. Estimates of the conversion coefficients show predominant M1 multipole order. Existence of at least two rotational cascades involving three or more levels is indicated. The about the same intensity. The energy ratios correspond to transitions between rotational levels having spins of 7/2, 9/2, 11/2 -and 13/2. The e- gamma coincidence relations support this interpretation and suggest the 282-kev transition as a cross over, whereas a 180-kev gamma in the coincident spectra possibly represents a transition from a 15/2 level. The coincidence measurements also seem to indicate coincidence with the 113- and 208-kev transitions; this is inconsistent with the spin 9/2 for the 321-kev level in Lu/sup 177/. The 123and 149-kev transitions with a 175-kev gamma possibly form a similar cascade built on a level at 412 kev. (L.N.N.)

The decay of 62 min Sn128 and 10.8 min Sb128

The decay of 62 min Sn/sup 128/ separated from products of U/sup 235/ thermal neutron fission and of its daughter 10.8 min Sb/sup 128/ was studied by gamma and BETA -ray spectrometry and by gamma - gamma and BETA - gamma coincidence measurements. The 62 min Sn/sup 128/ decay shows gamma rays at 44 plus or minus 1, 72 plus or minus 2, 497 plus or minus 6, and 570 plus or minus 10 kev and BETA rays at approximately 0.70 and 0.80 Mev. The 10.8 min Sb/sup 128/ decay shows gamma rays at 320 plus or minus 3 kev, 754 plus or minus 10 kev (2 gamma -rays), and 1070 plus or minus 20 kev in coincidence with a BETA ray at 2.45 Mev. Other BETA -transitions deduced from gamma -ray intensities are discussed, and a decay scheme is proposed. Gamma rays of adjacent Sn and Sb isotopes are presented but have not been further investigated. (auth)

Decay of Ruthenium-105

The decay of Ru/sup 105/ was studied employing two scintillation spectrometers in coincidence. It is found that Ru/sup 105/ decays to the excited levels of Rh/sup 105/ with the emission of six beta groups, with end-point energies of approximately 125, 525, 915, proximately approximately 0.002, 0.068, 0.11, 0.30, 0.51, and approximately 0.01, respectively. The subsequent gamma rays have the energies of 130, kev. From gamma - gamma and beta - gamma coincidence measurements, a level scheme of Rh/sup 105/ was worked out, showing the excited states at 130, 395, (or 530), 475, 725, 795, 960, 1350, and 1750 kev. (auth)

Decay ofK43

The decay of K/sup 43/ was reinvestigated in an attempt to clarify the discrepancies existing in the ordering of the energy levels of Ca/sup 43/. The external conversion spectrum showed lines corresponding to the following gamma- ray energies: 0.220 plus or minus 0.002, 0.37l plus or minus 0.002, 0.388 plus or minus 0.002, 0.394 plus or minus 0.002, 0.591 plus or minus 0.003, and 0.6l4 plus or minus 0.004 Mev. In addition a gamma ray of l.005 Mev was observed in the scintillation spectrum. BETA - gamma coincindence measurements establish that the gamma transitions to the ground state are the 0.371-Mev and the 0.59l-Mev gamma rays and not the 0.614-Mev gamma as believed previously. These results and the nu - gamma coincidence measurements indicate only one possible level scheme in Ca/sup 43/: 0, 0.371, 0.591, 0.985, and l.373 Mev. These energy levels as well as their proposed spin and parity assignments are in gound agreement with the results from the Massachusetts institute of Technology nuclear reaction data. A twocycle baffle for the solenoid BETA spectrometer is described. This baffle reduces significantly the background due to scattered gamma radiation from very strong external conversion sources. (auth)

Decay ofAs74

The decay of ${\mathrm{As}}^{74}$ (17.5-day) has been reinvestigated with single and coincidence scintillation spectrometers. The singles spectrum revealed previously unknown gamma rays of 1.19\ifmmode\pm\else\textpm\fi{}0.01, 1.60\ifmmode\pm\else\textpm\fi{}0.04, and 2.22\ifmmode\pm\else\textpm\fi{}0.02 Mev. X-ray---gamma coincidence measurements indicate the 1.19-Mev gamma ray is predominantly associated with the decay to ${\mathrm{Ge}}^{74}$. Evidence is found for 0.6-0.6 Mev gamma-gamma coincidences in ${\mathrm{Ge}}^{74}$. Based on these data, a level scheme for ${\mathrm{Ge}}^{74}$ is presented with excited states at 0.596, 1.19, and 2.22 Mev. No new information concerning the decay to ${\mathrm{Se}}^{74}$ has been gained.

32. Gamma coincidence measurements in 14N

32. Gamma coincidence measurements in 14N