R. A. Ricci

The gamma ray spectrum of63Zn

SummaryThe γ ray spectrum from the decay of63Zn was measured with scintillation techniques and a complete quantitative analysis was performed. The γ rays found are reported with their relative intensities in Table I and compared with the levels found in63Cu by the recent inelastic proton scattering experiment reported byMazari, Buechner andde Figueiredo. The main features of the proposed partial decay scheme of63Zn are discussed.RiassuntoUno studio completo dello spettro γ associato al decadimento del63Zn è stato compiuto per mezzo della tecnica a scintillazione. Una dettagliata analisi dello spettro ha permesso di trovare numerosi raggi γ, che sono riportati con le loro intensità relative nella Tabella I. Essi sono in buon accordo con i livelli del63Cu recentemente trovati per scattering inelastico di protoni daMazari, Buechner ede Figueiredo. Si discutono le caratteristiche essenziali dello schema di decadimento proposto.

A new technetium activity: 4.5 hour 94Tcm

Abstract A 4.5 ± 0.2 hour technetium activity has been produced by bombarding molybdenum, enriched in mass 94, with 16 MeV deuterons. It decays by a 1000 ± 50 keV position branch to a level at 2440 keV in 94Mo, which then emits a cascade of 860, 710 and 870 keV gamma rays. Comparison with the decay of 52 minute 94Tc, which takes place by position emission (2.41 MeV), accompanied by gamma rays of 870, 1530, 1870, 2410, 2730 and 3200 keV, makes the assignment of the 4.5 hour activity to mass 94 unambiguous.

Re-examination of the 66Ge decay

Abstract The energies and relative intensities of 89 γ-rays following the decay of 66 Ge to 66 Ga have been measured using Ge(Li) and Si(Li) spectrometers. The positon spectrum could be separated into four branches. Coincidence measurements were performed. By measuring the conversion electron spectrum with a Si(Li) KEVEX detector the conversion coefficients and multipolarities of some intense transitions could be determined. The total disintegration energy was calculated to be 2102 ± 13 keV. The existence of levels with the following energies was deduced: 43.89 ± 0.04(1 + ), 66.32 ± 0.04(2 + ) 108.95 ± 0.04(1 + ), 162.60 ± 0.06, 234.15 ± 0.05(2 + ), 290.96 ± 0.05(2 + ), 381.91 ± 0.03(1 + ), 536.74 ± 0.06(1 + ), 664.0 ± 0.5, 706.09 ± 0.04(1 + ), 866.04 ± 0.10 (1 + ), 974.65 ± 0.16(1), 1001.4 ± 0.3(0, 1), 1062.2 ± 0.2(0, 1), 1076.7 ± 0.1(0, 1), 1164.4 ± 0.1 (0, 1), 1210.3 ± 0.1(0, 1), 1456.54 ± 0.12(1 + ), 1556.71 ± 0.04(0 + , 1 + ), 1573.9 ± 0.1(0 + , 1 + ) and 1769.39 ± 0.16 keV (1 + ). The half-life of 66 Ge was measured to be 2.27 ± 0.05 h, that of the 43.89 keV level as

Disintegration of 66Ge

Abstract The decay of 66 Ge has been investigated by scintillation techniques. The beta and gamma ray spectra were measured and the experimental results are given in tables 1 and 2. Gamma-gamma coincidences have also been performed and the results are reported in table 3. On the basis of these data a decay scheme is proposed (see fig. 8) and some features of the 66 Ge disintegration are discussed.

The decay of 73Ga

Abstract The isotope 73 Ga was produced by fast neutron and deuteron bombardments of natural and enriched germanium; the decay was studied with scintillation and absorption techniques. The half-life is 4.85 ± 0.10 hours; there are two beta branches of 1.19 (94 %) and 0.4 (≈ 6%) MeV. Three gamma rays of 0.295, 0.745 and 1.04 MeV have been found, the first one of which is in coincidence with the higher energy beta group. A decay scheme is proposed (see fig. 1).

Gamma radiation from the decay of the95Tc ground state and from the93Tc isomeric pair

SummaryThe γ-ray spectra, following the decay of the 20 h95Tc ground state and of the 2.7 h93Tc ground state and its 43 min isomeric state, were studied by means of scintillation techniques. The sources were produced from enriched molybdenum targets. The energies (and relative intensities in per cent per decay) of the γ-rays from (20±1) h95Tc are: (205±5) (1.0%), (680±20) (2.0%), (765±5) (82±10%), (840±10) (10.5%), (930±10) (1.7%) and (1060±10) keV (4.0%) of which the first, second and fourth have not been reported before. The decay of the (43±2) min93Tc isomer only shows γ-rays of (390±5) (I.T., 82% per decay) and (2660±40) keV (18% per decay), that of the (2.7±0.1) h ground state shows 2 new transitions of (860±20) (2.6% per decay) and (2440±30) keV (0.3% per decay) in addition to the already known ones of (1350±10) (60%), (1490±10) (30%) and (2030±30) (0.35%) keV. A slightly revised decay scheme is proposed for93Tc.RiassuntoSi è studiato, con tecniche a scintillazione lo spettro γ associato al decadimento dello stato fondamentale del95Tc (20 h) e del93Tc (stato fondamentale 2.7 h e stato isomerico 43 min). Le sorgenti radioattive sono state prodotte bombardando con deutoni molibdeno arricchito. Il decadimento del95Tc (20±1 h) è accompagnato dalle seguenti transizioni γ (intensità relativa in % di disintegrazioni): (205±5) (1.0%), (680±20) (2.0%), (765±5) (82±10%), (840±10) (10.5%), (930±10) (1.7%) e (1060±10) keV (4.0%). Soltanto la transizione isomerica di (390±5) keV (82%) e una transizione γ di (2660±40) keV (18%) seguono il decadimento dell’isomero del93Tc (43±2 min), mentre 2 nuove transizioni di (860±20) keV (2.6%) e (2440±30) keV (0.35%) sono state trovate nel decadimento del93Tc (2.7±0.1 h). Vengono proposti degli schemi di decadimento.

On the decay of 67Ge

Abstract The beta and gamma spectra of the nucleide 67Ge, decaying with a half-life of 18.7±0.5 min, were studied with scintillation techniques. Three major positon groups were found, with observed endpoint energies of 3.14 (100+), 2.30 (40+) and 1.6 MeV (

Excited levels in57Co from the decay of57Ni

SummaryThe decay of57Ni has been the subject of an extensive investigation in order to obtain detailed information about the level structure of the odd-even57Co. Scintillation techniques have been used; particular attention has been devoted to possible γ-γ cascades, which were investigated by summing techniques (well-type crystal and Hoogenbooni spectrometers) in addition to the normal coincidence methods. Two new levels at 1750 and 1590 keV have been established with direct deexcitation to the57Co ground-state, in addition to the already known levels at 1890, 1490 and 1360 keV. It has been confirmed that the 1490 keV level is the only one which decays by a cascade of γ-rays. The decay scheme of57Ni is reviewed on the basis of the experimental results and the level structure of57Co is discussed from the point of view of the center of gravity theorem in nuclear spectroscopy. It is found that the situation for57Co is quite different from that of59Co, for which the theorem has been reported to be applicable. Some details about the experimental investigation of possible γ-γ cascades are discussed in the Appendix.RiassuntoSi è studiato in dettaglio il decadimento del57Ni per avere informazioni sulla struttura dei livelli del nucleo dispari-pari57Co. Si sono impiegate tecniche a scintillazione; si è fatta particolare attenzione alle possibili cascate γ-γ, che sono state studiate mediante le tecniche di somma (cristallo a buco e spettrometro di Hoogenboom) oltre che con coincidenze convenzionali. Si stabiliscono, in aggiunta agli altri livelli già conosciuti a 1890, 1490 e 1360 keV, due nuovi livelli a 1750 e 1590 keV che si diseccitano direttamente allo stato fondamentale del57Co. Si conferma che solamente il livello a 1490keV si diseccita mediante transizioni y in cascata. Lo schema di decadimento è rivisto sulla base dei risultati sperimentali ottenuti e la struttura dei livelli del57Co è discussa dal punto di vista del teorema del centro di gravita in spettroscopia nucleare. Si trova che la struttura del57Co è abbastanza diversa da quella del59Co a cui, secondo quanto riportato, il teorema è applicabile. Nell’appendice si discutono alcuni dettagli riguardanti l’indagine sperimentale di alcune possibili cascate γ-γ.

The gamma ray spectra of65Ni and65Zn; characteristics of the lower excited states of65Cu

SummaryThe γ-ray spectra of65Ni and of65Zn were studied by means of scintillation techniques. It is shown that the first excited state of65Cu at 770 keV is not populated in either of the decays. In65Ni (half-life: (2.50±0.03) h) two new γ-rays of (1.63±0.05) and (1.73±0.05) MeV were found, which originate at levels of the same energy known to exist in65Cu. Evidence is presented that the level at 1.482 MeV does not belong to the quartet of levels arising from the coupling of the 29th proton (p3/2) to the64Ni-core in its first excited 2+ state (at 1.34 MeV), as assumed by Lawson and Uretsky in their application of the center-of-gravity theorem to65Cu. Agreement with this theorem is obtained for certain spin assignments to the other four excited states in65Cu below 2 MeV.RiassuntoSi sono studiati gli spettri γ associati al decadimento radioattivo del65Ni e dello65Zn con tecniche di scintillazione. Si mostra che il primo livello eccitato del65Cu a 770 keV non è popolato da nessuno dei due decadimenti. Nel65Ni (periodo di dimezzamento (2.50±0.03) ore) si sono trovate due nuove transizioni γ di energia (1.63±0.05) e (1.73±0.05) MeV che hanno origine dai livelli aventi la stessa energia esistenti nel65Cu. La struttura di livelli del65Cu viene discussa in relazione al teorema del centro di gravità in spettroscopia nucleare. Si fa presente l’evidenza che il livello a 1.482 MeV non appartiene al quartetto di livelli ottenuti per accoppiamento del 29° protone (p3/2) al core del64Ni nel suo primo stato eccitato 2+ (a 1.34 MeV), come invece supposto da Lawson e Uretsky nell’applicazione del loro teorema al caso del65Cu. L’accordo con il teorema si ottiene per certe assegnazioni di spin agli altri quattro livelli eccitati.

On the decay of 74Ga

Synopsis The beta and gamma radiation from the decay of 8 minute 74Ga, produced by fast neutron bombardment of natural germanium and by deuteron bombardment of enriched 76Ge, was studied by means of scintillation techniques. In addition to very strong gamma rays of 0.600 and 2.35 MeV and five relatively strong gamma rays of 0.865, l.02, 1.20, 1.45 and 1.96 MeV, eleven weaker transitions were observed. Two beta ray branches could be resolved with maximum energies of 2.7 and 4.3 MeV. Some speculations are made about a possible level scheme for 74Ge.