A new 5.0 ns isomer in 144Eu

A new 9^? isomeric state having a 5.0 ns half-life has been observed in ¹⁴⁴Eu following the ¹⁴⁴Sm(α, p3n) reactions at 50 MeV. The new isomer most likely has a $\text{(π}\text{g}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{v}\text{h}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{)}{}_9{}^{\mathrm{?}}$ configuration.     

Rotational bands in the odd-odd 152Eu nucleus

The ¹⁵⁰Nd(⁷Li, 5n) reaction has been used to study the high-spin states in the odd-odd nucleus ¹⁵²Eu. Two rotational bands of different behaviour have been identified: a rather regular band based on the I^π = 8^? isomeric state of configuration $\text{[413}\text{5}\text{2}\text{]}{}_{\mathrm{<mtext>p</mtext>}}\text{[505}\text{11}\text{2}\text{]n}$ and a strongly decoupled system belonging to the configuration $\text{[}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{]}{}_{\mathrm{<mtext>p</mtext>}}\text{[i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}\text{]}{}_{\mathrm{<mtext>n</mtext>}}$.It is shown in this work that the aligned angular momentum carried by each two-quasiparticle configuration in ¹⁵²Eu is the sum of the alignment of the odd neutron and odd proton, which indicates a negligible influence of the neutron-proton residual interaction. Particular attention has been focused on the strong deviations of the moment of inertia of the core when different quasiparticle configurations are involved.     

The 154Eu(t,p) reaction: Some new systematics in the N = 90 spherical-deformed transition region

A radioactive target of ¹⁵⁴Eu(8.3y) has been used to study the ¹⁵⁴Eu(t, p)¹⁵⁶Eu reaction at an incident energy of 17 MeV. The bandhead and one rotational state of the configuration have been identified in ¹⁵⁶Eu. The excitation energy of the 3^? bandhead is determined to be 448 ± 15 keV. The angular distribution of the first excited rotational state is anamolous and may indicate evidence for a strong two-step component in the reaction mechanism. The energy systematics of the Eu-Sm transition region are also investigated. We find that the systematics of $\text{h}\text{?}{}^2\text{2}\text{I}$ suggest that at N = 87 the ¹⁵⁰Eu excited configurations has a significantly more stable deformed structure than the corresponding $\text{11}\text{2}\text{[505]}$ one-quasiparticle structure in ¹⁴⁹Sm.     

Evidence for shape coexistence in 151Eu

Although the ground states of ¹⁵¹Eu and ¹⁵³Eu both have $\text{I}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{+}}$, the (p, t) transition connecting these states is extremely weak. A level at 261 keV with a large (p, t) cross section is assigned as the deformed $\text{5}\text{2}{}^{\mathrm{+}}$[413] state in the “spherical” nucleus ¹⁵¹Eu.     

A study of the (n, α) reactions induced by 18 MeV neutrons in 151Eu, 151Eu, 159Tb, 16SHo and 169Tm

The energy spectra of α-particles emitted in the ${}^{151}\text{Eu(n}\text{, α)}{}^{148}\text{Pm}\text{,}{}^{153}\text{Eu(n}\text{, α)}{}^{150}\text{Pm}\text{,}{}^{159}\text{Tb(n}\text{, α)}{}^{156}\text{Eu}\text{,}{}^{165}\text{Ho(n}\text{, a)}{}^{162}\text{Tb and}{}^{169}\text{Tm(n}\text{, α)}{}^{166}\text{Ho}$ reactions have been measured at a neutron energy of 18.15 MeV. For the ${}^{165}\text{Ho(n}\text{, α)}{}^{162}\text{Tb}$ reaction the α-particle angular distribution has been measured as well. The results have been analysed in terms of statistical, pre-equilibrium and knock-on models.     

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.     

Polarization of 12B in deep-inelastic heavy-ion reaction 100Mo(14N, 12B)

Spin polarization of ¹²B was measured for ¹⁰⁰Mo(¹⁴N, ¹²B) at $\text{E}{}_{\mathrm{<mtext>i</mtext>}}\text{(}{}^{14}\text{N}\text{) ? 200}\text{MeV}$ as a function of $\text{Q}$ value down to $\text{Q ? ?150}\text{MeV}$, and was found anti-parallel to $\text{k}{}_{\mathrm{f}}\text{×}\text{k}{}_{\mathrm{i}}$ in the deep-inelastic region. The data together with those at lower incident energies show a systematic trend in $\text{Q}$-value dependence of the polarization.     

Static quadrupole moment of the 8− state of 112In

The quadrupole coupling constant $\text{(}\text{eQV}{}_{\mathrm{zz}}\text{h}\text{)}$ of the 8^? 606 keV level of ¹¹²In has been measured by the DPAD method in the hexagonal lattice of metallic cadmium. The quadrupole moment of the level is deduced to be |Q| = 0.093(6) in agreement with the theoretical value for the configuration $\text{[π(}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?1}}\text{ν(}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{)}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}{}^{\mathrm{n}}\text{]}{}_{\mathrm{8?}}$.     

Decay of 48K, 49K and 50K

The ⁴⁸K, ⁴⁹K and ⁵⁰K nuclides have been produced in high energy fragmentation and analyzed by mass spectroscopy techniques. Their half-lives have been measured as 6 ± 1 s, 1.1 ± 0.3 s and and 0.7 ± 0.3 s, respectively. The γ-rays from their radioactive decay have been observed and the corresponding γ-intensities measured. The nuclide ⁵⁰K is shown to be a delayed neutron emitter. The antianalog states in the daughter Ca nuclei with a $\text{(1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?}}$ neutron configuration, preferentially populated in the β-decay, have been located. The corresponding $\text{1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ neutron single-particle energy is found to remain approximately constant for these neutron-rich Ca isotopes.     

A high-spin isomer in 204Bi

By making use of heavy-ion and α-particle induced reactions an isomeric state has been found in ²⁰⁴Bi, with a half-life of $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 1.07 ± 0.03}\text{ms}$ and the quantum characteristics I^π = 16⁺. The four-quasiparticle configuration $\text{ν(}\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?2}}\text{ν(}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}{}^1\text{π(}\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^1$ has been ascribed to this state.     

Core polarization effects in the πh92 shell and g-factors of the 8+ states in 204Po and 206Po

The $\text{g-}\text{values of}\text{[(π}\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^2\text{, 8}{}^{\mathrm{+}}\text{]}$ isomeric levels in ²⁰⁴Po and ²⁰⁶Po have been measured with the stroboscopic method. The results obtained are: $\text{g(}{}^{204}\text{Po}\text{) = 0.923±0.013}\text{and}\text{g(}{}^{206}\text{Po}\text{) = 0.919±0.013}$. These and other known $\text{g-}\text{factors of}\text{(π}\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{n}}$ states in the ²⁰⁸Pb region are compared with theoretical predictions in order to analyze the dependence of the $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton g-value on the core constitution. The variation of the g-values is systematically smaller than expected from first-order configuration mixing theory, if pure shell-model wave functions are assumed.     

Magnetic moments of isomeric bandheads in transitional nuclei: 119I and 192Tl

Nuclear g-factors of isomeric bandheads in the transition nuclei ¹¹⁹I and ¹⁹²Tl have been measured to be $\text{g[}{}^{119}\text{I}\text{(}\text{9}\text{2}{}^{\mathrm{+}}\text{)] = 1.20(3)}$ and $\text{g[}{}^{192}\text{Tl}\text{(8}{}^{\mathrm{?}}\text{)] = 0.207(5)}$. These values are in agreement with a model of one or two quasiparticles coupled to a deformed core. This interpretation is also supported by a preliminary quadrupole moment determination of $\text{Q[}{}^{192}\text{Tl}\text{(8}{}^{\mathrm{?}}\text{)] = 45(9)}\text{fm}{}^2$. The lifetimes were remeasured to be $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 34.6(5)}\text{ns}$ and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 296(5)}\text{ns}$ for the ¹¹⁹I and the ¹⁹²Tl isomers, respectively.     

Rotational bands in 195, 197Tl

High-spin states in ^{195, 197}Tl have been populated with (α, xn) reactions and studied by means of in-beam γ-ray and e^? spectroscopic methods. Complementary studies of the decay of ^{195, 197}Pb to ^{195, 197}Tl have been carried out. Several new features have been observed in these nuclei. The $\text{9}\text{2}{}^{\mathrm{?}}$ bands of ^{195, 197}T1. extended to $\text{27}\text{2}{}^{\mathrm{(?)}}$ and $\text{29}\text{2}{}^{\mathrm{(?)}}$, respectively, show a quenching of energy spacings between the $\text{23}\text{2}{}^{\mathrm{?}}$, $\text{25}\text{2}{}^{\mathrm{?}}$, $\text{27}\text{2}{}^{\mathrm{(?}}$ and $\text{29}\text{2}{}^{\mathrm{(?}}$ states. This has been interpreted as resulting from the coupling of a $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton to the ($\text{π}\text{h}{}^{\mathrm{?2}}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{)}{}_{\mathrm{8+,\; 10+}}$ configurations in the core nuclei ^{194, 196}Hg. Furthermore, positive-parity bands based on $\text{15}\text{2}{}^{\mathrm{+}}$ states were established up to the $\text{35}\text{2}{}^{\mathrm{(+)}}$ and $\text{29}\text{2}{}^{\mathrm{(+)}}$ states in ^{195, 197}Tl respectively. Probably these bands originate from the coupling of a h${}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton to a broken neutron pair. This pair consists of a rotation-aligned $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ neutron and a low-j neutron in the $\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ or $\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ shell. It is known to constitute the 5^? bands in ^{194, 196}Hg.     

Structural connections between 148Sm and 149Sm nuclei

The ^{146, 148}Nd(α, χn) and ^{148, 150}Nd(³He, χn) reactions at E_α = 20–43 MeV and E_3He = 19–27 MeV, are used to study excited states in the ¹⁴⁹Sm₈₆ and ¹⁴⁹Sm₈₇ nucleides and consequently the low-spin odd-parity excitation. The mixing ratios and multipolarities of the most prominent transitions are deduced from the combined evidence of angular distribution and electron conversion data. The spin-parity assignments for most of the levels observed are established. In ¹⁴⁸Sm the ground state band extending to I^π = 10⁺ is predominantly populated. A negative-parity odd-spin band extending from I^π = 3^?through 11^? is also observed. The bands in ¹⁴⁸Sm are interpreted within the framework of the interacting boson approximation model. In ¹⁴⁹Sm positive-parity levels with spin up to $\text{25}\text{2}$ and negative-parity levels with spins up to $\text{21}\text{2}$ are observed. The predominant γ-decay proceeds via transitions associated with $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$, $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$, $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ and $\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ intrinsic configurations. The branching ratios B(E1)/B(E2) are calculated and compared in both ¹⁴⁸Sm and ¹⁴⁹Sm nucleides. The B(E1)/B(E2) dependence on the value of Z for some N = 86 (as well as 88 and 84) isotones showing a minimum of Z = 64 was noted. A 4 ns high-spin isomer mainly decaying into the positive-parity band based on the $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ state in ¹⁴⁹Sm is found. Experimental evidence is presented to interprete the $\text{1}\text{2}{}^{\mathrm{+}}$, $\text{15}\text{2}{}^{\mathrm{+}}$, … and $\text{9}\text{2}{}^{\mathrm{?}}$, $\text{13}\text{2}{}^{\mathrm{?}}$, …, ΔI = 2, sequences in ¹⁴⁹Sm as arising from the coupling of an $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ neutron to the octupole and quadrupole modes of the ¹⁴⁸Sm core nucleus. The absolute reaction cross sections for the ^{146, 148, 150}Nd(³He, χn) reactions have been determined for different bombarding energies. The mixing of the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ and $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ shells is discussed in the framework of an axial-particle-rotor model calculation.     

g-Factors of high-spin isomers in 194Hg and 196Hg

The g-factors of the 10⁺ isomeric states in ¹⁹⁴Hg and ¹⁹⁶Hg have been measured using the in beam IPAD method. The results $\text{g(}{}^{194}\text{Hg}\text{) = ?0.24(4)}$ and $\text{g(}{}^{196}\text{Hg}\text{) = ?0.18(9)}$ are in agreement with the value expected for an ($\text{i}{}_1\text{3}\text{2}$^?2) neutron satructure and clearly contradict the previous assignment as ($\text{h}{}_{\mathrm{<mtext>1</mtext><mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{?2}}$) proton configurations. Cranking model calculations show that the neutron excitation energies in the rotating frame agree satisfactorily with the experimental energies and that the proton excitations are expected ≈2 MeV above the experimental yrast line     

Study of the three-proton three-neutron-hole nucleus 208At

Levels in ²⁰⁸At were populated in the ²⁰⁹Bi(α, 5n) reaction, and the subsequent radiation was studied using γ-spectroscopic methods including γ-ray excitation function and angular distribution, γγ(t) coincidence and γt measurements, as well as measurements of conversion electrons. The excited spectrum of ²⁰⁸At is found to consist of two almost disconnected parts which are proposed to originate from seniority-three proton and neutron cascades. Two isometric states are observed. A $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 45 ± 2}\text{ns}$ state at 1090 keV is proposed to have the main configuration and J^π = 10^?. A high-spin isomer with $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 1.5 ± 0.2 μs at 2276}\text{keV}$ is assigned to be the state. Shell-model arguments are used to assign configurations to most of the observed levels. Transition rates are discussed.     

Backbending behaviour of rotational bands in 163,165,167Yb

Several rotational bands in ^163,165,167Yb are observed in (HI,xnγe^?) experiments. The $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ and $\text{3}\text{2}{}^{\mathrm{?}}\text{[521]}$ bands do not backbend, whereas the $\text{5}\text{2}{}^{\mathrm{?}}\text{[523]}$ bands do, indicating additional processes besides the rotational alignment of one $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ neutron pair that are responsible for the backbending.     

Magnetic moment of the 2543 keV 7+ state in 40K

The nuclear g-factor of the 2543 keV, 7⁺ state ⁴⁰K has been measured as g = 0.59 ± 0.10. Time-integral perturbed angular distributions were measured in an external magnetic field and, after implantation, in the hyperfine field at potassium in nickel. The experimental value is discussed within the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^2\text{and}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?2}}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^2$, configurations.