Nuclear reaction studies of 168Tm
Abstract
The intrinsic structure of 168Tm has been studied using the (3He, d) and (α, t) proton stripping reactions as well as the (d, t) and (3He, α) neutron pick-up reactions. The beams of 24 MeV 3He particles, 25 MeV α-particles and 12 MeV deuterons were obtained from the McMaster tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The spectra have been interpreted in terms of the coupling of an odd proton and an odd neutron, each moving independently in a spheroidal potential, which gives rise to intrinsic two-quasiparticle states with . The identification of the intrinsic states was made by comparing the experimental cross-section patterns with those predicted with the aid of Coriolis coupling and distorted-wave Born approximation (DWBA) calculations. Rotational bands superimposed on the Kπ = 3+ and configurations, the first of which is the ground state, ha been observed in the spectra of all four reactions. New assignments have been made for configurations resulting from coupling the − [541], + [404], + [402] and − [530] p to the + [633] neutron state. The neutron pick-up measurements confirmed the earlier assignments based on (d, t) reaction studies and suggested tentative assignments for the {+ [400]n±+ [411]p} and {+ [402]n±+ [411]p}
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Nuclear data sheets for A = 168
2010, Nuclear Data SheetsNuclear structure data pertaining to all nuclei with mass A=168 (Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt) have been evaluated and incorporated into the ENSDF data file. This evaluation supersedes the previous publication (V.S. Shirley, Nuclear Data Sheets 71, 261 (1994) (literature cutoff date July 1993)) and subsequent ENSDF file revisions for Tb and Dy (C. Baglin, literature cutoff date of 15 June 1999) and Hf (B. Singh, literature cutoff date of 30 April 2001), and includes literature available by 15 June 2010. Since the above evaluations, the first excited states in 168Pt have been identified (1998Ki20, 2009Go16) and α decay from 172Hg has been observed (2009Sa27, 2004Ke06, 1999Se14). New levels in 168Dy have been excited using the 170Er(82Se,84Krγ) reaction (2010So03). (HI,xnγ) studies have significantly expanded our knowledge of level structure in 168Lu (1999Ka17, 2002Ha33), 168Ta (2008QiZZ), 168Yb (1995Fi01), 168Tm (2007CaZW), 168Hf (2009Ya21), 168Os (2001Jo11, 2009Od02) and, for 168Tm, important information has come also from (d,2nγ) and (α,nγ) reactions (1995Si20). Revised decay schemes are available following new studies of 168Hf ε decay (6.7 min) (1997Ba26), 168Lu ε decay (1999Ba65), 168Ta ε decay (2007Mc08) and 172Au α decay (2009Ha42). Significant new information for 168Er is available from (p,t) (2006Bu09), (d,p) and (t,d) (1996Ma50), (γ,γ′) (1996Ma18), (136Xe, Xγ) (2010Dr02), (238U,238) (2003Wu07) and (n,γ) (1998Be20, 1998Be62) reactions, and the availability of γγ coin data (1994Ju02, 1996Gi09) for the (n,γ) E=thermal reaction has resulted in some significant level scheme revisions.
Odd-even staggering in the K = 1, 2, 3 and 4 rotational bands of deformed odd-odd nuclei
1988, Physics Letters BAn analysis of the rotational structure of the bands in the odd-odd nuclei from the rare earth region reveals an odd-even staggering in the level energies. Such an odd-even effect is present, sometimes very prominently, in almost all the K− bands with K values ranging from 1 to 4. We find that complete Coriolis coupling calculations are able to explain most of the staggering in the four nuclei studied. However, the K = 2+ and K = 4− bands in 182Re cannot be explained satisfactory.
Nuclear Data Sheets for A=168
1988, Nuclear Data SheetsExperimental data pertaining to all nuclei with mass A=168 have been evaluated. Level schemes from both radioactive decay and reaction studies are presented, along with associated tables of experimental data and adopted properties for levels and transitions.
Levels in <sup>154</sup>Eu populated by (n, γ) and (d, p) reactions
1987, Nuclear Physics, Section AThe structure of the doubly-odd nucleus 154Eu was investigated using neutron capture and (d, p) reactions on 153Eu. The low-energy γ-ray and conversion electron spectra from thermal neutron capture, as well as the γ-ray spectrum for primary energies up to 6.5 MeV, were measured with precision instruments at the Institut Laue-Langevin, Grenoble. The multipolarities were determined for most of the detected low-energy transitions. The (nres, γhigh) spectrum measurements with 2 keV, 2 eV and 3 eV neutrons were performed at Brookhaven National Laboratory for primary transitions leading to the 0–600 keV excitation energies. The 153Eu(d, p)154Eu reaction was measured with the Q3D spectrograph at TU Munich. A level scheme below 600 keV excitation energy comprising 99 levels was deduced and the parities and most probable spin values were determined from the experimental data. The low-lying levels were interpreted as due to the two-particle Nilsson configurations, taking into account the proton orbits , and the neutron orbits . The 145.3 (± 0.3) keV level observed in the (d, p) reaction can be identified with the isomeric level with . The neutron separation energy for 154Eu was determined to be 6442.0 ± 0.3 keV.
The residual n-p interaction in doubly odd deformed nuclei
1976, Nuclear Physics, Section AResidual interaction calculations have been made for two-quasiparticle states in doubly odd rare earth nuclei. A comparison between theory and experiment has been made for 78 band head energy splittings and 20 odd-even shifts using a central two-body interaction with a Gaussian radial dependence that includes both short and long range components. Most of the splittings derived from definite configuration assignments were fitted well by the calculations. In addition, the interaction potential was reasonably well specified by the least squares fit to the splitting energies for a fixed pair of interaction radii. The odd-even shifts could not be fitted simultaneously with the splitting energies.
The effective neutron-proton interaction in rare-earth nuclei
1976, Physics ReportsThe available experimental information concerning the low-lying rotational-band energies in rare-earth nuclei with odd neutron and proton numbers is analysed within the framework of the unified model. We extract 69 empirical values for 51 two-particle matrix elements of the effective neutron—proton interaction in 16 nuclei. This information deals with 43 two-quasi-particle configurations. Strength and range parameters for various types of effective interaction are determined from least-squares fits of calculated matrix elements to the empirical values. We find a significant improvement in the fit when spin-polarized and long-range components are included in the effective force, indicating the importance of core-polarization effects. We investigate the sensitivity of the calculation to the choice of experimental information, to the single-particle model, and to the radial shape of the force. Some predictions are made concerning as yet unconfirmed or unobserved configurations.
- †
On leave of absence from the Institute of Nuclear Research, Warsaw, Poland.