Rotational bands in Ho

The excited states of the deformed odd-proton nucleus ¹⁶¹Ho have been studied in the reactions ¹⁵⁹Tb(, 2n), ¹⁶¹Dy(d, 2n) and ¹⁶¹Dy(p, n). Gamma-ray spectra in single and coincidence modes as well as angular distributions and excitation functions of the transitions were measured. The proposed level scheme of ¹⁶¹Ho contains besides of the ground state band ⁻[523] the bands ⁺[404], ⁺[411], ⁺[411] and ⁻ [541] (band heads at 252.7, 298.7, 211.2 and 423.9 keV, respectively). An attempt was made to estimate the influence of Coriolis coupling between the bands ⁺ [411] and ⁺ [411], which are very close in energy. The ⁺ [404] band was found to de-excite by very fast E1 transitions to the ground state band ⁻[523]. Nilsson retardation factors of about 0.03 for these transitions were deduced using the E2/E1 branching ratios. An investigation has also been made of the independent feeding of the levels from high-lying states.     

Superdeformed bands in153Ho

In a recent experiment carried out with theEurogam Phase II γ-ray spectrometer three new superdeformed (SD) bands have been established in¹⁵³Ho. The properties of these SD bands are discussed in terms of proton particle-hole excitations and are compared to the SD bands in the adjacent nuclei. This is the first observation of SD structures in aZ=67 nucleus.     

Rotational bands in77Kr

Collective bands in⁷⁷Kr have been studied with the help ofγ singles spectra,γγ coincidences,γ ray angular distributions and recoil-distance life time experiments measured during the irradiation of⁶³Cu and⁶⁴Ni targets with¹⁶O ions. Positive and negative parity bands with the following level energies, spins, and parities have been found: g.s. 5/2⁺; 150.1 keV 7/2⁺; 279.1 9/2⁺; 784.8 11/2⁺; 1003.7 13/2⁺; 1660.5 15/2⁺; 1919.1 (17/2⁺); 66.5 keV (3/2)^?; 245.3 (5/2)^?; 499.6 (7/2)^?; 799.5 (9/2)^?; 1177.3 (11/2)^?; 1569.9 (13/2)^?; 2063.2 (15/2)^?. A mean life time of 170±17 nsec for the 66.5 keV state was measured withγγt coincidences and a mean life time of 48±13 psec for the 245.3 keV state was obtained with a recoildistance Doppler shift measurement.     

Rotational bands in 181Ta

High-spin states in ¹⁸¹Ta have been studied via the ¹⁷⁶Yb(¹¹B,α2n) reaction at 52 MeV using the PEX array and at 57 MeV using the NORDBALL array, with α-particle detection. The previously known, K^π=(7/2)⁺ ground state band and K^π=(9/2)⁻ band have been extended to spins (29/2)⁺ and (31/2)⁻, respectively. Two new one-quasiparticle bands, the K^π=(5/2)⁺ band built on the known (5/2)⁺ isomer and a K^π=((1/2)⁻) band have been observed. Two other rotational bands with three-quasiparticle structure, K^π=(15/2)⁻ and ((19/2)⁺ with π(7/2)[404]ν²(1/2)[510](9/2)[624] and π(9/2)[514]ν²(1/2)[510](9/2)[624] configurations, respectively, have been newly observed. The half-life of the K^π=((19/2)⁺) bandhead which decays to the head of the (15/2)⁻ band has been measured to be 140(36) ns. However, transitions from the ((19/2)⁺) state to the (15/2)⁻ band have not been observed. Received: 26 August 1998     

Rotational bands in79Kr

The level scheme of⁷⁹Kr has been studied through the⁷⁹Br(p,n)⁷⁹Kr reaction at proton energies from 1·7 to 5·0 MeV.γ-ray and internal conversion electron measurements were made using Ge(Li) detectors and a six gap “Orange” electron spectrometer. The level scheme was established by determining the thresholds of variousγ-rays and byγ-γ and n-γ coincidence measurements. New levels at 402, 450, 660, 676, 695, 720, 810, 836, 907 and 1038 keV not observed in earlier radioactivity studies have been established. DefiniteJ ^π assignments have been made to most of the levels below 800 keV. Many of the low-lying levels are identified as rotational levels based on the (301 ↓) 1/2^?, (301 ↑) 3/2^? and (431 ↓) 1/2⁺ Nilsson states.     

Rotational bands in 169Re

Based on the systematic investigation of the data available for nuclei with A≥ 40, a Z ^1/3-dependence for the nuclear charge radii is shown to be superior to the generally accepted A ^1/3 law. A delicate scattering of data around R _c/Z ^1/3 is inferred as owing to the isospin effect and a linear dependence of R _c/Z ^1/3 on N/Z (or (N - Z)/2) is found. This inference is well supported by the microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) calculation conducted for the proton magic Ca, Ni, Zr, Sn and Pb isotopes including the exotic nuclei close to the neutron drip line. With the linear isospin dependence provided by the data and RCHB theory, a new isospin-dependent Z ^1/3 formula for the nuclear charge radii is proposed. Received: 23 September 2001 / Accepted: 21 January 2002     

Rotational bands in 167Hf

High-spin states in ¹⁶⁷Hf, populated in the ¹⁴¹Pr(³⁰Si, p3n)¹⁶⁷Hf reaction, have been studied using the nordball Ge detector array. Three rotational cascades have been observed for the first time and the previously-known level scheme has been extended to significantly higher spin. Band-crossing effects are discussed within the framework of Woods-Saxon cranking calculations and are found to be in good agreement. Received: 9 April 1999 / Revised version: 13 May 1999     

Rotational bands in the 170Er nucleus

A critical analysis of the entire body of available experimental data on the excited states of the deformed even-even nucleus ¹⁷⁰Er is performed. By contrasting the spectrum of gamma rays from the relevant (n, n′γ) reaction against data from other processes, it is possible to reveal new K ^π=0^? and 2^? bands and to establish new levels, including rotational levels of known bands, with allowance for the moments of inertia. The structure of the excited states of ¹⁷⁰Er is investigated on the basis of the Nilsson scheme and of the quasiparticle-phonon model.     

Rotational bands in odd hafnium nucleides

Rotational bands up to high-spin members in odd-neutron Hf nucleides are studied by in-beam spectroscopy using (α, xn) reactions on isotopically enriched Yb targets. The $\text{1}\text{2}{}^{\mathrm{?}}$ [521], $\text{5}\text{2}{}^{\mathrm{?}}$ [512], and the $\text{7}\text{2}{}^{\mathrm{+}}$ mixed positive-parity (mainly $\text{7}\text{2}{}^{\mathrm{+}}$ [633]) bands were observed in ¹⁷³Hf and ¹⁷⁵Hf while the $\text{7}\text{2}{}^{\mathrm{?}}$ [514], $\text{9}\text{2}{}^{\mathrm{+}}$ (mainly $\text{9}\text{2}{}^{\mathrm{+}}$[624]), and the $\text{3}\text{QP}\text{(K =}\text{23}\text{2}$⁺) bands were studied in ¹⁷⁷Hf. The analysis of the band structure within the Nilsson model is extended to also include adjacent odd Hf nuclei making it possible to follow these bands through five isotopes of Hf.     

Rotational bands in light neutron-rich nuclei

A simple cluster model is used to describe rotational bands in light neutron-rich nuclei. It is concluded that bands observed earlier had a cluster structure.     

Rotational side bands in 160Dy

The ¹⁵⁸Gd(α, 2n)¹⁶⁰Dy reaction has been used to study rotational side bands in ¹⁶⁰Dy. Several negative-parity bands are observed, with several members of K^π = 1⁻, 2⁻ and 4⁻ bands and of a K^π = 8⁻ band only the bandhead. A pronounced odd-even staggering of moments of inertia is found for members of the K^π = 2⁻ band. Of the positive-parity bands the K^π = 2⁺ (γ) band, which is seen up to a possible spin of 12 and low-spin members of K^π = (0⁺), (S), and 4⁺ bands are observed. The mixing between most of the γ-band and S-band members is observed to be smaller than 2% and no evidence for possible anti-alignment of low-spin S-band members with rotation is found.     

Rotational bands in the light odd-mass Tl nuclei

The odd-mass nuclei ^191–197Tl have been formed in a variety of (HI, xn) reactions and studied by in-beam spectroscopic techniques. The decay of the high-spin Pb isomers, also formed in (HI, xn) reactions, leading to ^193–197Tl has also been investigated. Evidence is presented for the existence of levels of the previously proposed $\text{9}\text{2}{}^{\mathrm{?}}\text{[505]}$rotational bands in the nuclei. Tentative evidence is given for the existence of oblate rotational bands, based on the $\text{13}\text{2}{}^{\mathrm{+}}\text{[606]}$ state, in ^191–195Tl.     

Rotational bands in the near-drip-line nucleus 128Nd

The even-even nucleus ¹²⁸Nd was studied via in-beam γ-ray spectroscopy using the ⁴⁰Ca + ⁸²Mo reaction at 190 MeV. Two new bands were observed besides the yrast one, that has been extended up to spin 34⁺. Configurations were assigned to the three bands by analysing their rotational properties and by comparison with the neighboring even-even nuclei. Received: 18 July 2001 / Accepted: 25 October 2001     

Rotational bands in the doubly odd 130Cs nucleus

The band structures built on the 5^- isomeric state ( T _1/2 = 3.46 m) in the doubly odd ¹³⁰Cs nucleus have been established up to I = 24? via the ¹²⁴Sn(¹¹B, 5n)¹³⁰Cs reaction. The previously observed bands based on the πh _11/2⊗νh _11/2, πg _7/2⊗νh _11/2 and πd _5/2⊗νh _11/2 configurations and a positive-parity side band with multiple connections to the α = 0 signature partner of the yrast πh _11/2⊗νh _11/2 band have been extended to higher spins. A new band based on the πh _11/2⊗νg _7/2 configuration is observed. The yrast πh _11/2⊗νh _11/2 band exhibits anomalous signature splitting whose magnitude decreases up to spin 15 and then increases without restoring the normal signature splitting. Received: 20 February 2001 / Accepted: 9 May 2001     

Rotational analysis of the ultraviolet bands of PS

The 2-0, 1-0 and 0-0 bands of the ultraviolet system of PS have been analysed for their rotational structure. It is shown that they involve the transitionC ² Σ -X ² Π _r (a). TheC ² Σ state shows a significant spin doubling.     

Investigation of lifetimes in dipole bands of 141Eu

Lifetimes have been measured for dipole bands in ¹⁴¹Eu using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (Shears mechanism with Principal Axis Cranking) models. The dipole bands can be interpreted as magnetic rotational bands.Received: 6 April 2004, Revised: 14 May 2004, Published online: 13 July 2004PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 21.10.Tg Lifetimes - 27.60. + j      

β-delayed proton decay of the proton drip-line nucleus 142Ho in the rare-earth region

New β-delayed proton precursor 142Ho was produced via heavy ion induced reaction 106Cd(40Ca, p3n), and identified for the first time by using a He-jet fast tape transport system in combination with "p-γ" coincidence measurements. The β-delayed proton decay of 142Ho was observed and its half life was determined to be (0.4±0.1) s. By fitting the experimental relative branching ratios to final states in the proton daughter nucleus 141Tb and the energy spectrum of β-delayed protons with a statistical model calculation, the ground-state spin of 142Ho was assigned as 5, 6 or 7. Nuclear energy-potential-surface (EPS) calculations were performed using the Woods-Saxon Strutinsky method. The calculated results favored the assignments of 7- to 142Ho. AS the by-products, some γ-transitions in the proton daughter nuclei following the β-delayed proton decays of precursors 139Gd, 140Tb, 142Tb, and 143Dy were reported here for the first time.