Gamma-ray spectroscopy of 64Zn and 65Zn and the role of the g92 orbital

Measurements of γ-ray excitation functions, γ-γ coincidence spectra and γ-ray angular distributions have been made. following the reactions ⁶¹Ni(α, n)⁶⁴Zn, ⁶²Ni(α, n)⁶⁵Zn, ⁵⁶Fe(¹⁴N, αnp)⁶⁴Zn, ⁵⁶Fe(¹²C, 2pn)⁶⁵Zn, and ⁵⁴Fe(¹²C, 2p)⁶⁴Zn. Among the new levels observed in ⁶⁴Zn are those at 5624 keV, 6765 keV, 6940 keV, and 6124 keV, the last one with a suggested assignment of (9^?). In ⁶⁵Zn. ten new levels probably in the positive-parity chain, with spin up to ($\text{21}\text{2}$), and a few others, have been found. Comparison of the ⁶⁵Zn positive-parity levels with the ⁶⁴Zn ground-state band supports the concept of a single neutron in the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ orbital weakly coupled to a core essentially identical to ⁶⁴Zn. Many high-spin states in ⁶⁴Zn itself can be aggregated into bands whose band heads are suggestive of two-quasiparticle states involving one $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ excitation.     

Nuclear orientation study of the excited states of 129I populated in the decay of 129gTe and 129mTe

From the angular distributions of γ-rays emitted by oriented ^129gTe and ^129mTe nuclei implanted in iron by isotope separator, unique spin assignments could be made for the excited states of ¹²⁹I at 487.4 keV $\text{(}\text{5}\text{2}{}^{\mathrm{+}}\text{)}$, 696.0 keV $\text{(}\text{11}\text{2}{}^{\mathrm{+}}\text{)}$, 729.6 keV $\text{(}\text{9}\text{2}{}^{\mathrm{+}}\text{)}$, 768.9 keV $\text{(}\text{7}\text{2}{}^{\mathrm{+}}\text{)}$, 1050.4 keV $\text{(}\text{7}\text{2}{}^{\mathrm{+}}\text{)}$ and 1111.8 keV $\text{(}\text{5}\text{2}{}^{\mathrm{+}}\text{)}$. In addition, E2/M1 amplitude ratios for the following ¹²⁹I γ-rays (energies are in keV) are derived: δ(459.6) = ?(0.076^+0.037_?0.148); δ(487.4) = 0.50^+0.17_?0.10 or δ^? = 0.35^+0.15_?0.09; δ(556.7) = 0.06±0.02 or δ^? = ?(0.10±0.02); δ(624.4) = 0.10±0.26 or δ^? > 0.4; the 696.0 keV γ-ray is pure E2; δ(729.6) = ?(0.34±0.06) or δ^?1 = 0.55±0.05; δ(741.1) = ?(0.27±0.10) or δ^?1 = ?(0.43±0.12); δ(817.2) = 0.46±0.04 or δ^?1 =0.20±0.03 if $\text{I}{}^{\mathrm{\pi }}\text{(845}\text{keV}\text{) =}\text{7}\text{2}{}^{\mathrm{+}}$; δ(1022.6) = ?(0.02 ±0.02) or δ^?1 = ?(0.23±0.02); $\text{δ(1084) = 0.56}{}^{\mathrm{+0.04}}{}_{\mathrm{?0.14}}$; δ(1111.8) = 0.06±0.05 or δ^?1 = ?(0.08±0.05). The anisotropy of the 531.8 keV γ-ray excludes $\text{1}\text{2}{}^{\mathrm{+}}$ as a possible spin assignment for the 559.6 keV level, so that no $\text{1}\text{2}{}^{\mathrm{+}}$ level is fed in the decay from ¹²⁹Te. Anisotropies for the 209, 250.7, 278.4 and 281.1 keV γ-rays are also measured. Comparison of the level scheme is made with theoretical predictions from both the pairing-plus-quadrupole model and the intermediate coupling unified model.     

High spin states in 57Co

High spin states of ⁵⁷Co have been studied via prompt γ-ray spectroscopy in the reactions ⁴⁸Ti(¹²C, p2n) and ⁵⁴Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable J^π assignment of $\text{15}\text{2}{}^{\mathrm{?}}$, if $\text{17}\text{2}{}^{\mathrm{?}}$ and $\text{19}\text{2}{}^{\mathrm{?}}$, respectively. The previously known level at 2524 keV was assigned to have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{?}}$. These together with the known $\text{9}\text{2}{}^{\mathrm{?}}$(1224 keV) and $\text{11}\text{2}{}^{\mathrm{?}}$(1690 keV) levels constitute the yrast states of ⁵⁷Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10_?0.07^+0.06, 1.5_?0.5⁴ and 0.17_?0.07^+0.08 ps, respectively. Comparisons with some theoretical calculations are presented.     

Electromagnetic transitions in 51Mn

The nuclear structure of ⁵¹₂₅Mn was studied by γ-ray spectroscopy in the ⁵⁴Fe(p, α)⁵¹ Mn reaction (E_p = 9.0–13.2 MeV) and the ¹⁴N+³⁹K, ¹⁶O+⁴⁰Ca and ¹⁴N+⁴⁰Ca fusion-evaporation reactions (E_beam = 36 MeV). In the ⁵⁴Fe(p, αγ)⁵¹Mn reaction γ-rays were detected in coincidence with α-particles emitted near 180°; mean lifetimes and γ-ray mixing and branching ratios were deduced from Doppler shift attenuation and α-γ angular correlation measurements, respectively. Definite spin assignments are: 237 and 2416 keV, $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}$; 1140 keV, $\text{9}\text{2}$^?; 1488 keV, $\text{11}\text{2}$^?; 1825 and 2140 keV, $\text{3}\text{2}$^?. The results for other states below 3 MeV are consistent with the existence of rotational bands (/kh²/2/OI/t~ 95 keV) built on the ($\text{3}\text{2}$⁺) 1817 keV and $\text{1}\text{2}$⁺ 2276 keV hole states. The various measurements together with an earlier value for the lifetime of the first-excited state determine unambiguously the B(M1) and B(E2) values for all of the decay branches of the $\text{7}\text{2}$^?, $\text{9}\text{2}$^? and $\text{11}\text{2}$^? lowest three excited states. From the γ-singles and γ-γ coincidence observations with fusion-evaporation reactions, the yrast cascade proceeds through these three states and higher states at 2957, 3250,3680 and 4139 keV which are suggested to have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{?}}$, $\text{15}\text{2}$^?,$\text{15}\text{2}$^? and $\text{19}\text{2}$^?, respectively. The various experimental results for the $\text{5}\text{2}$^? → ($\text{19}\text{2}$^?) yrast states are in good overall agreement with shell-model calculations in the (f_{$\text{7}\text{2}$}¹ space.     

Beta decay studies in the vicinity of 13250Sn82: Excited states in 13051Sb, 13052Te and 13252Te

Using the OSIRIS on-line isotope separator facility, the decays of ¹³⁰Sn and ^{130, 132}Sb have been studied. On the basis of singles γ and γ-γ coincidence Ge(Li) spectra and conversion electron Si(Li) measurements, level schemes for ¹³⁰Sb, ¹³⁰Te and ¹³²Te have been constructed. The corresponding half-lives have been measured using multiscaling technique. The 3.8 min ground state of ¹³⁰Sn populates only positive parity states in the πν^?3 nucleus ¹³⁰Sb: the energetically lowest 5⁺ state with the $\text{(π1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, ν2}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}$ configuration assignment; the $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 3.6 ± 0.3}\text{ns}\text{4}{}^{\mathrm{+}}$ state at 70.0 keV; the 2⁺ state at 262.5 keV; the (0, 1)⁺ state at 697.2 keV; the 3⁺ state at 813.1 keV and the 1⁺ state at 1042.3 keV excitation energy. A 1.7 min isomeric state in ¹³⁰Sn, with the tentative spin assignment (7^?), populates several odd parity levels in ¹³⁰Sb. These arise from the $\text{(π1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, ν1}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}{}^{-1}\text{)}$ and/or $\text{(π2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{, ν1}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}{}^{-1}\text{)}$ configurations and are located 84.7 keV (6^?), 144.9 keV (7^?), 688.5 keV and 1044.0 keV above the 40 min 8^? β- decaying state. No transitions between odd and even parity states have been observed.The most important excited states in ¹³⁰Te found in the β^? decay of the 6.6 min ¹³⁰Sb 5⁺ state are: 839.4 keV, 2⁺; 1632.8 keV, 4⁺; 1815.1 keV, 6⁺; 2100.8 keV, 5^?.Levels in the π²ν^?2 nucleus ¹³²Te were observed in the β^? decays of the 2.8 min ¹³²Sb (4⁺) and the 4.2 min ¹³²Sb (8^?) states. Unique spin and parity assignments have been given to the following states: 973.9 keV, 2⁺; 1670.7 keV, 4⁺; 1774.1 keV, 6⁺; 1924.7 keV, 7^?; 2053.0 keV, 5^?.     

Gamma transitions in 59Ni following the β+ decay of 59Cu

The γ-ray decay spectrum of 82 s ⁵⁹Cu produced by the ⁵⁸Ni(p, γ) ⁵⁹Cu reaction has been studied with a 40 cm³ Ge(Li) detector. The number of γ-rays now known for this decay has more than doubled. Additional direct β⁺ branches to the 1679.7($\text{5}\text{2}{}^{\mathrm{?}}$), 2414.8($\text{3}\text{2}{}^{\mathrm{?}}$) and 2681 keV states of ⁵⁹Ni have been identified with log ft values of 5.5, 5.5 and 6.0, respectively. A major change is the reassignment of the 1340.4 keV γ-ray to a 1679.7 → 339.3 keV transition. A limit of log $\text{ft ≧ 6.9}$ is given for the direct feeding of the 1337($\text{7}\text{2}{}^{\mathrm{?}}$) keV state, together with limits for direct population of other energetically available states. The new weak γ-ray branches found for the 878.0, 1301.5 and 1679.7 keV levels are in excellent agreement with the recent theoretical calculations of Glaudemans et al.     

Band structures in 98Ru and 99Ru

The level schemes of ^{98, 99}Ru were studied with the reactions ⁹⁸Mo(α, 3nγ) and ⁹⁸Mo(α, 4nγ) at E_α = 35 to 55 MeV, using a large variety of in-beam γ-ray detection techniques and conversion-electron measurements. A search for the 3^? state was carried out with the reaction ⁹⁸Ru(p, p′). The ground-state band of ⁹⁸Ru was excited up to J^π = (12)⁺ and a negative-parity band up to (15)^?. New levels in ⁹⁸Ru were found at E_x = 2285 (J^π = 4⁺), 2435 (J^π = (3^?, 4⁺)), 2671, 3540, 4224, 4847, 4915 (J^π = (12)⁺), 4989 (J^π = (12⁺)), 5521 (J^π = (13)^?), 5889, 6591 (J^π = (15)^?), and 7621 keV. New unambiguous spin and parity assignments were made for the levels at E_x = 2014 and 3852 keV, as J^π = 3⁺ and 9^?, respectively. New levels in ⁹⁹Ru were found at E_x = 1976, 2021 ($\text{J}{}^{\mathrm{\pi }}\text{= (}\text{15}\text{2}{}^{\mathrm{+}}\text{)}$), 2393, 2401 ($\text{J}{}^{\mathrm{\pi }}\text{= (}\text{17}\text{2}{}^{\mathrm{+}}\text{)}$), 2875 (π = (+)), 3037, 3201 ($\text{J}{}^{\mathrm{\pi }}\text{= (}\text{23}\text{2}\text{)}{}^{\mathrm{?}}$), 3460 ($\text{J = (}\text{17}\text{2}\text{)}$), 3484 ($\text{J}{}^{\mathrm{\pi }}\text{= (}\text{21}\text{2}{}^{\mathrm{+}}\text{)}$), 3985, 4224 ($\text{J}{}^{\mathrm{\pi }}\text{= (}\text{27}\text{2}{}^{\mathrm{?}}\text{)}$), and 5359 keV. The 1070 keV, $\text{J}{}^{\mathrm{\pi }}\text{=}\text{11}\text{2}{}^{\mathrm{?}}$ level in ⁹⁹Ru has a half-life of 2.8 ns. A strongly excited negative-parity band is built on this level. A positive-parity band based on the ground state was excited up to $\text{J}{}^{\mathrm{\pi }}\text{= (}\text{21}\text{2}{}^{\mathrm{+}}\text{)}$. The level schemes are well reproduced by the interacting boson model in the vibrational limit.     

Electron capture decay of 245Bk (4.90 d) and 246Bk (1.80 d)

The electron capture decay schemes of ²⁴⁵Bk and ²⁴⁶Bk have been investigated by measuring the γ-ray and conversion-electron spectra of mass-separated ²⁴⁵Bk and ²⁴⁶Bk samples. The γ-ray spectra were measured with a 25 cm³ Ge(Li) spectrometer and the conversion-electron spectra were measured with a cooled Si (Li) detector. Multipolarities of most of the transitions in ²⁴⁵Cm and ²⁴⁶Cm were deduced. The half-lives of ²⁴⁵Bk and ²⁴⁶Bk were determined by following the decay of the 252.85 and 798.7 keV photopeaks and were found to be 4.90 ± 0.03 d and 1.80 ± 0.02 d, respectively. The α/(α+EC) ratio for the ²⁴⁵Bk decay was measured to be (1.2 ± 0.1) × 10^?3. On the basis of the present investigation the following non-rotational states were identified in ²⁴⁵Cm: $\text{7}\text{2}{}^{\mathrm{+}}$ [624], 0; $\text{5}\text{2}{}^{\mathrm{+}}$[622], 252.85; $\text{1}\text{2}{}^{\mathrm{+}}$ 355.95; $\text{3}\text{2}{}^{\mathrm{?}}$ vibrational, 633.65; and $\text{1}\text{2}{}^{\mathrm{+}}$[620], 740.95 keV. The $\text{3}\text{2}{}^{\mathrm{?}}$ state at 633.65 keV is int as a K_π = 2^? phonon coupled to the i$\text{7}\text{2}{}^{\mathrm{+}}$[624] single-particle state. Our measurements of ²⁴⁶Bk γ-ray and conversion-electron energies and intensities confirm previous level assignments in ²⁴⁶Cm.     

The level structure of 184W FROM THE β− decay of 184Ta

Levels of ¹⁸⁴W populated in the decay of 8.7 h ¹⁸⁴Ta have been studied by a variety of experimental techniques. As a result of β and γ-ray energy and intensity determinations and extensive β-γ and γ-γ coincidence measurements, a detailed ¹⁸⁴Ta decay scheme accommodating more than 99.5% of the decay intensity has been established. Intense β-ray groups of end-point energies 1165±26 and 1123±26 keV populate levels in ¹⁸⁴W at 1699 and 1746 keV, which de-excite predominantly to the 8.3 μs isomeric level at 1285 keV, recently identified as the $\text{1}\text{2}{}^{\mathrm{?}}\text{[510]ν?}\text{11}\text{2}{}^{\mathrm{+}}\text{[615]ν K}{}^{\mathrm{\pi }}\text{= 5}{}^{\mathrm{?}}$ band origin. The 1699 keV level also de-excites to members of a $\text{1}\text{2}{}^{\mathrm{?}}\text{[510]ν?}\text{7}\text{2}\text{[503]ν K}{}^{\mathrm{\pi }}\text{= 3}{}^{\mathrm{+}}$ band based at 1425 keV. New information about the properties of the γ-vibrational and K = 2 octupole bands in ¹⁸⁴W is presented and the possible configurations of the levels directly populated in the β^? decay are discussed. The configuration $\text{7}\text{2}{}^{\mathrm{+}}\text{[404]π ?}\text{3}\text{2}{}^{\mathrm{?}}\text{[512]ν K}{}^{\mathrm{\pi }}\text{= 5}{}^{\mathrm{?}}$ is indicated for the ¹⁸⁴Ta ground state.     

Alpha-decay of 39.3 h 254mEs isomer

Mass-separated samples of ^254mEs were used to investigate its α-decay scheme. Twelve α-groups were identified in a spectrum measured with the Argonne magnetic α-spectrometer. The favored α-transition populates a 211.8 keV level in ²⁵⁰Bk and four members of its rotational band were observed. A three-parameter α-γ time coincidence experiment showed that the 211.8 keV level decayed by three routes: two were prompt and one was delayed. The delayed γ-rays (50.07, 71.30, 90.7, 104.0, 126.0 and 175.7 keV) decayed with a 42±2ns half-life. The energies of the prompt γ-rays were 79.90, 96.3, 177.3 and 211.8 keV. From an α-ce^? coincidence experiment the multipolarity of the 211.8 keV transition was deduced to be E1. The α-branching was determined from an α-singles spectrum and was found to be 0.33±0.01%. From the results of the present investigation and the known properties of ²⁵⁰Bk and ^254mEs, the 211.8 keV state in ²⁵⁰Bk and the ^254mEs ground state were given $\text{{}\text{n}\text{[622]}\text{3}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}{}^{\mathrm{+}}\text{2}{}^{\mathrm{+}}$ assignment. Other levels in ²⁵⁰Bk were postulated at 104.0 (and its rotational member at 125.3), 131.9 and 175.3 keV and these were given tentative assignments of $\text{n}\text{[620]}\text{1}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[521]}\text{3}\text{2}{}^{\mathrm{?}}\text{1}{}^{\mathrm{?}}\text{,}\text{n}\text{[620]}\text{1}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}{}^{\mathrm{+}}\text{3}{}^{\mathrm{+}}$ and $\text{n}\text{[613]}\text{7}\text{2}{}^{\mathrm{+}}\text{;}\text{p}\text{[633]}\text{7}\text{2}\text{O}{}^{\mathrm{+}}$ (with I = 1), respectively. The splitting energies between the parallel and antiparallel coupled states were calculated with a Gaussian potential for the residual neutron-proton interaction and were found to be in agreement with the experimental values. A precise measurement of the energies and intensities of γ-rays and K X-rays associated with the ^254mEs β^? decay was also made. The Fm K_α2 and K_α1 energies were found to be 115.280±0.015 and 121.065±0.015 keV, respectively.     

Lifetimes of low-lying states in 19F

Lifetimes of low-lying states in ¹⁹F were measured using the Doppler-shift attenuation method through the ¹⁵N(α, γ)¹⁹F reaction. Values of τ_m = 3700 ± 700 fs (1.35 MeV), 140 ± 15 (1.46), 19 ± 7 (4.00) and 63 ± 19 (4.03) were obtained for the lowest $\text{5}\text{2}{}^{\mathrm{?}}$, $\text{3}\text{2}{}^{\mathrm{?}}$, $\text{7}\text{2}{}^{\mathrm{?}}$ and $\text{9}\text{2}{}^{\mathrm{?}}$ members, respectively, of the $\text{K}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{?}}$ rotational band and 5 ± 3 fs (1.55 MeV) and 370 ± 25 (2.78) for the $\text{3}\text{2}{}^{\mathrm{+}}$ and $\text{9}\text{2}{}^{\mathrm{+}}$ members of the $\text{K}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$ ground-state band. For the Doppler-shift attenuation analysis correction factors of the nuclear and electronic stopping powers were determined by measuring the Doppler-shift attenuation and γ-ray line shape of the 2.78 → 0.20 MeV transition and range values of 100, 200. 300 and 370 keV ¹⁹F nuclei in tantalum. All calculations were done with Monte Carlo methods. The transition strengths are discussed in terms of different theoretical predictions.     

Coulomb excitation of 85Rb and 87Rb

Energy levels of ⁸⁵Rb and ⁸⁷Rb have been studied via de-excitation γ-rays following Coulomb excitation with ³⁵Cl ions. In addition to the known negative-parity states at 151.2 keV and 868.2 keV in ⁸⁵Rb, two states at 281.0 keV and 731.8 keV have been found with fourγ-ray transitions of 129.8, 281.0, 450.8 and 731.8 keV. Only one Coulomb excited state at 402.6 keV in ⁸⁷Rb has been observed. The B(E2↑) values (in units e² · b²) have been determined as 0.0035±0.0004 (151.2 keV), 0.0016±0.0002 (281.0 keV), 0.0101 ±0.0010 (731.8 keV), and 0.036±0.004 (868.2 keV) for the states in ⁸⁵Rb, and as 0.0054±0.0006 (402.6 keV) for the state in ⁸⁷Rb. The mean lifetimes of the 731.8 keV and 868.2 keV states have been measured by the Doppler shift attenuation method as 6.4±0.7 psec and 4.2±0.5 psec respectively. Angular distribution measurements allow unique spin and parity assignments of $\text{1}\text{2}{}^{\mathrm{?}}$ and $\text{3}\text{2}{}^{\mathrm{?}}$ to the 281.0 keV and 731.8 keV levels respectively. The spin and parity of the 868.2 keV level has been restricted to $\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}$.     

High-spin states in 40K investigated with the 26MG + 16O reaction

Yrast levels in ⁴⁰K and ⁴⁰Ar have been investigated with the ²⁶Mg(¹⁶O, pnγ)⁴⁰K and ²⁶Mg(¹⁶O, 2pγ)⁴⁰Ar reactions at a beam energy of 34 MeV. Gamma-ray angular distribution and γ-γ coincidence measurements have been performed with a high-resolution large volume Ge(Li)-NaI(Tl) Compton-suppression spectrometer. Gamma-ray linear polarizations have been measured with a three-crystal Ge(Li) Compton polarimeter. The ⁴⁰K decay scheme involves new high-spin levels at E_tx = 4365.6±0.3, 4875.6±0.4 and 6227.0±0.5 keV with lifetime limits of < 1, < 1 and < 2ps, respectively. Unambiguous spin-parity assignments of $\text{J}{}^{\mathrm{\pi }}\text{= 5}{}^{\mathrm{?}}\text{, 6}{}^{\mathrm{+}}\text{, 8}{}^{\mathrm{+}}\text{, 9}{}^{\mathrm{+}}\text{and}\text{(8, 10)}{}^{\mathrm{?}}$ to the ⁴⁰K levels at E_x = 0.89, 2.88, 4.37, 4.88 and 6.23 and of $\text{J}{}^{\mathrm{\pi }}\text{= 4}{}^{\mathrm{+}}\text{and}\text{6}{}^{\mathrm{+}}\text{to the}{}^{40}\text{Ar}$ levels at E_x = 2.89 and 3.46 MeV, respectively, have been obtained. Branching ratios and multipole mixing ratios are reported.     

The γ-decay of the g92 analogue state in 59Cu

An investigation of the γ-decay of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ analogue state in ⁵⁹Cu has been performed using the ⁵⁸Ni(p, γ)⁵⁹Cu reaction. The (p, γ) excitation function has been taken in the range E_p = 3450–3650 keV. The decay schemes of the (p, γ) resonances at E_p = 3483, 3532 and 3547 keV, measured with Ge(Li) detectors, lead to eight new levels in ⁵⁹Cu with excitation energies between 1.8 and 4.7 MeV and to spin assignments of several states. The spins of the first two resonances are found to be ($\text{1}\text{2}$, $\text{3}\text{2}$) and ($\text{5}\text{2}$). The spin of the E_p = 3547 keV resonan is, from angular distributions, uniquely determined to be $\text{J}{}^{\mathrm{\pi }}\text{=}\text{9}\text{2}{}^{\mathrm{+}}$ and this state is found to be the unfragmented analogue state of the $\text{E}{}^1\text{= 3.062}\text{MeV}$, $\text{J}{}^{\mathrm{\pi }}\text{=}\text{9}\text{2}{}^{\mathrm{+}}$ parent state in ⁵⁹Ni. The measured complete decay scheme of this resonance shows that its isovector M1 decay is in disagreement with all existing theoretical predictions.     

Excited levels of 233Pa by alpha decay of 237Np

α-spectrometry using Si(Au) detectors has been performed with thin samples of ²³⁷Np; αγ bi-parametric coincidences have permitted an analysis and unfolding of the spectrum and give data about the level scheme. Direct and α-coincident γ-spectra have been measured using Ge(Li) and Si(Li) detectors, obtaining the characteristic electromagnetic transitions in ²³³Pa. Nine new γ-transitions are found, relative to the most recent compilation made by Ellis. In the level scheme, the existence of a level at 306.1 keV is confirmed. A level at 257.1 keV, previously suggested, is evidenced. The level at 300.5 keV is proposed as the $\text{7}\text{2}{}^{\mathrm{?}}$ component of the $\text{5}\text{2}\text{(523)}$ band, hence proposing the 306.1 keV level as the $\text{7}\text{2}{}^{\mathrm{+}}$ term of the $\text{5}\text{2}\text{(642)}$ band.     

Level structure of 75Se by the 75As(p,nγ)75Se reaction

Excitation functions of γ-rays from the ⁷⁵As(p, n)⁷⁵Se reaction were measured with 2.0 to 3.6 MeV protons to establish the level scheme of ⁷⁵Se up to about 1.5 MeV excitation energy. Internal conversion electrons following the same reaction were measured at 4.5 and 5.0 MeV proton energy. Using theoretical predictions of the statistical compound nucleus model together with deduced internal conversion coefficients, unique spin assignments were obtained for the $\text{112.5(}\text{7}\text{2}{}^{\mathrm{+}}\text{), 427.9(}\text{5}\text{2}{}^{\mathrm{?}}\text{)}$ and $\text{663.9(}\text{5}\text{2}{}^{\mathrm{?}}\text{)}\text{keV}$ levels. Probable spins were proposed to the $\text{286.6 (}\text{3}\text{2}{}^{\mathrm{?}}$ for one of the doublet and $\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}$ for the other), 579.4 $\text{(}\text{1}\text{2}{}^{\mathrm{?}}$ or $\text{3}\text{2}{}^{\mathrm{?}}$, $\text{585.8(}\text{9}\text{2}{}^{\mathrm{?}}$ or $\text{11}\text{2}{}^{\mathrm{?}}$ and $\text{747.6 (}\text{5}\text{2}{}^{\mathrm{?}}$ or $\text{7}\text{2}{}^{\mathrm{?}}\text{)}\text{keV}$ levels. Alow-lying $\text{9}\text{2}{}^{\mathrm{+}}$ level was tentatively assigned at 133.2 keV energy. It was found that a low-lying $\text{1}\text{2}{}^{\mathrm{?}}$ level which appears systematically in other odd Se nuclei is absent in ⁷⁵Se.     

Spin-parity assignments to high-spin states of 41K and 41Ca

Yrast states of ⁴¹K and ⁴¹Ca have been investigated with the ²⁶Mg(¹⁸O, p2nγ)⁴¹K and ²⁶Mg(¹⁸O, 3nγ)⁴¹Ca reactions at a beam energy of 34 MeV. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization measurements were performed with a Ge(Li)-NaI(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. Unambiguous spin-parity assignments of $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{+}}$, $\text{11}\text{2}{}^{\mathrm{+}}$, $\text{11}\text{2}{}^{\mathrm{?}}$, $\text{13}\text{2}{}^{\mathrm{+}}$, $\text{15}\text{2}{}^{\mathrm{?}}$ and $\text{19}\text{2}{}^{\mathrm{?}}$ to the ⁴¹K levels at E_x = 1.68, 2.53, 2.76, 2.77, 4.27 and 4.98 MeV and of $\text{9}\text{2}{}^{\mathrm{+}}\text{,}\text{11}\text{2}{}^{\mathrm{+}}\text{and}\text{15}\text{2}{}^{\mathrm{+}}$to the ⁴¹Ca levels at E_x = 3.20, 3.37 and 3.83 MeV, respectively, have been obtained. Excitation energies, branching ratios, multipole mixing ratios and transition strengths are reported. The main features of the ⁴¹K and ⁴¹Ca level and decay schemes are reproduced in a 2p-1h and 3p-2h shell-model calculation.     

Nuclear structure studies of 97Ru from the decay of 97g,mRh

The energy levels of ⁹⁷Ru have been studied through the decay of 31.1 min ^97gRh and 44.3 min ^97mRh using Ge(Li), Si(Li), Nal, plastic and anthracene detectors in singles and in coincidence experiments. A total of 139 γ-rays were observed. Ninety-eight γ-rays have been placed into the decay schemes involving 38 excited levels in ⁹⁷Ru. The level energy of ^97mRh was determined to be 258.6 keV. The spin and parity of ^97gRh and ^97mRh are assigned as $\text{9}\text{2}{}^{\mathrm{+}}\text{and}\text{1}\text{2}{}^{\mathrm{?}}$, respectively. The fraction of decay of the isomer by the isomeric transition was measured with the Si(Li) detector, and α_k values were determined for strong transitions. The half-life of the 188.6 keV, $\text{3}\text{2}{}^{\mathrm{+}}$ state in ⁹⁷Ru was determined as 0.23 ± 0.02 ns by delayed e-γ coincidence measurements. The nuclear structure of low-lying levels is compared with similar levels in other odd-mass nuclei (N = 53) isotones and Ru isotopes).     

Ground-state properties of 3h 184Ir and 14h 185Ir

The ground-state spectroscopic quadrupole moments of ${}^{184}\text{Ir [J}{}^{\mathrm{\pi }}\text{=(5}{}^{\mathrm{\pm }}\text{);t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{=3.00]}$ and ${}^{185}\text{Ir (J}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{?}}\text{;t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 14}\text{h}\text{)}$ have been determined by nuclear orientation as +2.2(4) b and ?2.03(3) b, respectively. The negative QM of ¹⁸⁵Ir can be explained only by a $\text{J}{}^{\mathrm{\pi }}\text{K=}\text{5}\text{2}{}^{\mathrm{?}}\text{1}\text{2}$ ground-state configuration. The positive QM of ¹⁸⁴Ir implies K ? 4 in contradiction to expectations of K=0, 1 in analogy to ¹⁸⁶Ir.     

Medium-spin levels and the character of the 20.4 ns 132+ isomer in 145Gd

Levels of the N = 81 nucleus ¹⁴⁵Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the ¹⁴⁴Sm(³He, 2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin $\text{21}\text{2}{}^{\mathrm{+}}$, five other high-spin non-yrast states and a new 20.4 ns $\text{13}\text{2}$ isomer at 2200.2 keV in ¹⁴⁵Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 ± 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1 + M2 + E3 transition to the $\text{v}\text{h}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ state. We propose an octupole $\text{v}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{j}{}^{\mathrm{?2}}\text{× 3}{}^{\mathrm{?}}$ main configuration for the isomer, analogous to the 997 keV $\text{13}\text{2}{}^{\mathrm{+}}$ isomer in ¹⁴⁷Gd. The levels of ¹⁴⁵Gd are discussed on the basis of the spherical shell model.