First observation of a superdeformed nucleus produced in an α xn reaction channel

Excited states in the neutron deficient ¹⁴⁵ Dy nucleus have been identified by means of the reaction ¹¹²Sn(³⁵ Cl,pn) at 159 MeV. The level scheme above the 11/2 ^? state and up to spin I～37/2 was obtained using γ-ray spectroscopy methods. The level structure is discussed in terms of the coupling of a h _11/2 neutron hole with the N=80 core excitations.     

Quadrupole moments of superdeformed bands in 193Tl

Lifetimes of states in the two strongest superdeformed (SD) bands in ¹⁹³Tl were measured using the Doppler-shift attenuation method. The reaction ¹⁷⁶Yb(²³Na,6n)¹⁹³Tl at a beam energy of 129 MeV was used and γ-rays were detected by the Gammasphere array. Quadrupole moments of 18.3(10) eb and 17.4(10) eb were extracted for SD bands 1 and 2, respectively, using the fractional Doppler-shifts of the SD transitions. The previously reported linking transitions of these SD bands to normal deformed near yrast levels could not be confirmed. No other candidates for linking transitions could be established. Received: 27 April 1999     

Possible candidates for discrete gamma rays linking superdeformed and yrast states in an odd nucleus:193Pb

The francium isotopes^200–202Fr were produced in the reaction³⁵Cl+¹⁷⁰Yb using bombarding energies of 4.9–5.3 MeV/nucleon. Fusion products were separated in-flight from the primary beam using a gas-filled recoil separator. An alpha line with the alpha particle energy and half-life of (7468±9) keV and (19 ₋₆ ⁺¹³ ) ms, respectively, was assigned to²⁰⁰Fr. Previously reported decay properties of^201,202Fr were confirmed. Communicated by V. Metag     

Observation of superdeformed bands in194Hg

Two rotational bands, with energy spacings characteristic of superdeformed shapes, have been observed following bombardment of¹⁵⁰Nd with⁴⁸Ca. The more intensively populated band consists of 18 transitions and is assigned to¹⁹⁴Hg. The depopulation of this band occurs around spin 10. The second band, consisting of at least 16 transitions, was populated less strongly and is tentatively assigned to¹⁹⁴Hg also. The lowest level in this band is assigned spin 8. The energy differences between transitions for both bands decrease from ～40 keV at low rotational frequencies to ～30 keV at the highest observed frequencies. The moments of inertia of the bands are similar to those of the two previously observed superdeformed bands in^191,192Hg. The similarities and differences of the four known bands in the mercury region are discussed.     

Superdeformed bands in193Hg and194Hg

By analyzing the thick target yield curve of resonant (p,γ) reactions on²³Na and²⁶Mg for various target temperatures within a Monte Carlo approach, we are able to define the Debye and Einstein temperature of the target material in the surface region. The obtained surface temperatures are noticeably higher than the respective calorimetric values.     

Characterization of the superdeformed band in189Hg

New measurements of the pionic double charge exchange on⁵⁶Fe exhibit a pronounced energy dependence of this reaction at low energies in accordance with similar observations on other nuclei. We show that this peculiar energy dependence finds its natural explanation by a resonance in theNN subsystem withJ ^p =0^–,T=0 and a mass of 2.065 GeV.This work has been funded by the German Federal Minister for Research and Technology (BMFT) under the contract numbers 06 TÜ 656 and 06 KA 266 and by the DFG (Mu 704/3, Graduiertenkolleg)     

Magnetic dipole transitions in the superdeformed bands of 193Tl

By analysis of fission product γ-rays measured at Eurogam II using a ²⁴⁸Cm source, the (vf_7/2)² multiplet in the N = 84 nucleus ¹³⁴Sn has been identified up to a 6⁺ isomeric state at 1246 keV. The B(E2; 6⁺→4⁺) is determined to be 36±7 e²fm⁴ corresponding to a vf_7/2 E2 effective charge of 1.02±0.10.10 e.     

Decay of193m Hg

The decay of^193m Hg to¹⁹³Au levels was investigated by means of Ge(Li) and Ge(Li)-NaI(Tl) coincidence spectrometers. In theγ-ray spectrum about 120 transitions were observed, about 80 of them being new. Forty coincidences betweenγ-transitions were observed. The level scheme of¹⁹³Au, including 12 earlier known levels as well as 17 new and corrected levels, has been constructed on the basis of the balance of energy sums and the observed coincidences. Possible multipolarities of 33 transitions were determined. Possible spins and parities of several levels were deduced from the determined multipolarities.     

New results on the superdeformed band in192Hg

New results on the¹⁹²Hg superdeformed band have been obtained with EUROGAM. The experiment has been performed with the¹⁶⁰Gd(³⁶S,4n) reaction at 159 MeV. Above 800 keV the γ-ray energies differ from the previously published ones. Thus the rise of the dynamical moment of inertia $\mathfrak{F}^{(2)} $ above ?ω=0.4 MeV is no longer observed. This is in better agreement with recent cranked Hartree-Fock-Bogoliubov calculations.     

Lifetime measurements and decay of superdeformed bands in Hg isotopes

The lifetimes of states in Superdeformed (SD) bands in ^192,194Hg have been measured using the Doppler shift attenuation method. Intrinsic quadrupole moments have been extracted for band 1 of ¹⁹²Hg and for bands 1, 2, and 3 of ¹⁹⁴Hg. It was found that the quadrupole moments for the “identical” SD bands in these nuclei are the same. In the same experiment, one-step transitions linking SD states to yrast and near yrast states for bands 1 and 3 of ¹⁹⁴Hg have been identified. From this observation, excitation energies, spins and probable parities have been assigned to SD states in these bands.     

First triaxial superdeformed band in 170Hf

First evidence is presented for triaxial superdeformation in ¹⁷⁰Hf. High-spin states in this nucleus have been investigated in a γ-ray coincidence measurement using the EUROBALL spectrometer array. A new band was discovered which has moments of inertia that are very similar to the ones of triaxial superdeformed bands in neighbouring Hf and Lu nuclei. The intensities with which these bands are populated are different from what may be expected from calculated potential-energy minima. Received: 11 September 2002 / Accepted: 15 October 2002 / Published online: 10 December 2002 RID="a" ID="a"e-mail: neusser@iskp.uni-bonn.de Communicated by D. Schwalm