H.R. Koch

Level scheme and gamma transitions in 52V

Abstract The thermal neutron capture gamma-ray spectrum of 52V has been measured with the curved crystal spectrometer at the DR-3 reactor in Riso. A level scheme is constructed using the energies and intensities of capture gamma lines between 20 keV and 1 MeV. The levels are identified as the low-lying part of the configurations ( proton 1 f 3 2 ) 3 ( neutron 2 p 1 2 , 2 p 1 2 or 1 f 5 2 ) , which have been studied by shell model calculations with effective proton-proton and proton- neutron interactions. The spectroscopic factors of the proton groups leading to these states in the 51V(d, p)52V reaction and the relative reduced M1 transition probabilities between them are satisfactorily reproduced by the calculations.

Nuclear levels in152Eu

The transitional nucleus152Eu has been studied using the (n, e), (n, γ), (nres,γ), (n, γγ), (d, p), (d, t) and (p, d) reactions. The experiments have been performed at nine different laboratories. A model independent level scheme was established including 95 levels below 510 keV and nearly 900 transitions by combination of low energy transitions and reaction data. More than 20 additional levels result from gamma rays and/or charged particle reactions. The level scheme is interpreted in terms of the Nilsson model indicating that152Eu is a deformed nucleus. Seven rotational bands and Nilsson configurations are established. An additional 27 rotational bands are tentatively or speculatively assugned. Gallagher-Moszkowski splittings are discussed. The neutron binding energy was determined as 6305.2±0.5 keV. The energy of the 9.3 h 0− isomer is 45.599 keV. The lifetimes of four levels were measured.Nuclear Reactions151Eu(n,γ),En=thermal and resonance; measuredEγ,Iγ,Ec.e.,Ic.e.,γγ Coinc.,γγΔt coinc.;151Eu(d, p),E=12MeV and 14MeV;153Eu(d, t),E=12MeV;153Eu(p, d),E =18MeV; deduced level scheme of152Eu,J, π, T1/2,cc, Nilsson configurations. Magnetic electron spectrometer, curved crystal spectrometer, Ge(Li) and Si(Li) detectors, magnetic spectrographs. Enriched targets.

Energy levels of 56Mn

Abstract The low-energy spectrum of the 55 Mn(n, γ) 56 Mn reaction has been studied with a γ-diffraction spectrometer. These data allowed the construction of a level scheme for 56 Mn with two previously unobserved doublets. High-energy γ-transitions to the low-energy states have been measured for different neutron resonances at the BNL fast neutron chopper. For most states a unique spin and parity could be proposed. A shell-model calculation of the structure of the low-lying states of 56 Mn has been carried out with the Oak Ridge-Rochester computer programme; there are plausible theoretical analogues for 11 of the 12 experimentally observed states. Calculated spectroscopic factors and M1 transition probabilities are in qualitative agreement with the experiment.

Nuclear levels in 160Tb

Abstract The high energy γ-ray spectrum from thermal neutron capture in natural terbium has been studied over the energy range of 5200 to 6400 keV. Low energy γ-radiation of the same reaction has been observed from 20 to 1230 keV and conversion electrons from 6 to 160 keV. Low energy (n, γγ) coincidences have been measured. A value of 6375.1 ± 0.3 keV has been obtained for the neutron binding energy in 160Tb. The data, when combined with a previous 159Tb (d, p) study, allow a level scheme to be constructed. These levels are assigned to nine rotational bands built on two quasiparticle configurations. The decay of several other levels is discussed. In three cases we have observed both parallel and antiparallel coupled bands with K − = ¦Ω p −Ω n ¦ and K + = Ω p + Ω n , and found the Gallagher-Moszkowski rule to be valid. The energy splitting has been calculated using Nilsson wave functions and a δ-force. Two K = 1 bands with irregular level spacing have been observed.

The level scheme of 176Lu investigated by (n, γ) and (n, e) reactions

Abstract The excited levels of 176 Lu have been studied using the conversion electron and γ-spectra from slow neutron capture in 175 Lu measured with the β-spectrograph at Riga and with the diffraction spectrometer at Riso. The proposed level scheme contains the rotational bands with the following lowest levels E , I π K and Nilsson configurations: 126 keV , 1 − 0, p 7 2 + [404]− n 7 2 − [514] ; 198 keV , 1 + 1, p 7 2 + [404]− n 9 2 + [624]; 342 keV , 1 + 1, p 9 2 − [514]−n 7 2 − [514]; 390 keV , 1 − 1, p 7 2 + [404]− 5 2 − [512]; 638 keV , 4 + 4, p 1 2 − [541]+ n 7 2 − [514]; 641 keV , 1 − 1, p 5 2 + [402]−n 7 2 − [514]; 660 keV , 5 + 5, p 9 2 − [514]+ n 1 2 − [510]; 662 keV , 3 − 3, p 7 2 + [404]−n 1 2 − [510]; 726 keV , 4 − 4, p 1 2 + [411]+ n 7 2 − [514] . The bands with 0 keV, 7 − 7, p 7 2 + [404]+ n 7 2 − [514] and 404 keV, 8 + 8, p 7 2 + [404]+ n 9 2 + [624] , can be discussed only on the basis of earlier (d, p) and (d, d′) reaction data.

Low-energy level scheme of 46Sc deduced from the 45Sc(n, γ)46Sc capture gamma rays

Abstract The thermal neutron capture gamma-ray spectrum of the reaction 45 Sc(n, γ) 46 Sc has been measured with the Riso bent crystal gamma spectrometer. Some 27 gamma transitions out of a total of 53, representing nearly 95% of the sum of the measured intensities, have been fitted in the level scheme. For most levels, spin and parity assignments are proposed and discussed on the basis of the present experimental results.

The nuclear structure of198Au from the reaction197Au(n, γ)198Au

Precise energies and intensities of about 450γ-rays of the197Au(n, γ)198Au reaction have been investigated in the energy range from 30 keV to 1 MeV with a bentcrystal spectrometer. Prompt and delayedγ-γ coincidences have been studied with Ge(Li) detectors. A half-life of 124±4 ns has been measured for the state at 312.036 keV, which is found to decay to the ground state through the cascade 97.195–214.841 keV. A new level scheme based on these results has been constructed which contains 160 transitions. Spin and parity assignments have been made for most of the levels.

Gammastrahlung vom Einfang thermischer Neutronen in Hg 199

Abstract103 gamma transitions in Hg 200 have been observed. 37 of them were fitted into a level scheme which comprises 17 states. The energy of the one-phonon vibrational stateI=2+ has been determined to be 367.970±0.020 keV, that of the two-phonon vibrational triplet 947.34±0.07 keV, 1029.37±0.05 keV and 1254.20±0.10 keV. Further levels have been found at energies of 1570.30±0.10 keV, 1571.7±0.6keV, 1594.3±0.4 keV, 1631.5±0.2 keV, 1641.5±0.3 keV, 1718.5±0.2 keV, 1730.8±0.2 keV, 1775.7±1.1 keV, 1842.9±0.8 keV, 1882.9±0.3 keV, 2062.6±0.5 keV and 2082.9±1.0 keV.

Investigation of the low-lying levels of 179Hf with the (n, γ) and (n, e) reactions

The excited levels of 179Hf are investigated using the thermal neutron capture γ-ray and conversion electron spectra measured with the bent crystal diffraction spectrometer in Riso and the β-spectrograph in Riga. The level scheme contains the odd parity rotational bands 72−[514], 12−[510], 52−[512], 12−[521], 32−[512] and 72−[503]. The energies of these levels and the intensity ratios of the transitions between them are calculated taking into account the rotation-particle coupling (RPC). The following even parity levels are proposed: 859.0 and 942.2 keV (72+ and 92+ of the 72+ [633] band); 1004.1 and 1079.2 keV (52+ and 72+ of the 92+[624] + Q(22) band); 1186.0, 1199.2 and 1296.4 keV (12+, 52+ and 32+ of the 12+[651] band). The levels at 1249.8, 1269.7, 1432.9, 1482.2 and 1755.5 keV, supported by the analysis of the γγ coincidence spectrum and Ge(Li) singles data, are discussed.