Prompt proton decay scheme of (59)Cu

Five prompt proton decay lines have been identified between deformed states in (59)Cu and three spherical states in (58)Ni by means of high-resolution in-beam particle-gamma gamma coincidence spectroscopy. The GAMMASPHERE array coupled to dedicated ancillary detectors including four Delta E-E silicon strip detectors was used to study high-spin states in (59)Cu. The multiple discrete proton lines are found to probe the wave functions of states in the decay-out regime of well- and superdeformed states.     

B and collider physics: Working group report

This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in Working group on ‘B and collider physics’.     

Electromagnetic transitions in 51Mn

The nuclear structure of ⁵¹₂₅Mn was studied by γ-ray spectroscopy in the ⁵⁴Fe(p, α)⁵¹ Mn reaction (E_p = 9.0–13.2 MeV) and the ¹⁴N+³⁹K, ¹⁶O+⁴⁰Ca and ¹⁴N+⁴⁰Ca fusion-evaporation reactions (E_beam = 36 MeV). In the ⁵⁴Fe(p, αγ)⁵¹Mn reaction γ-rays were detected in coincidence with α-particles emitted near 180°; mean lifetimes and γ-ray mixing and branching ratios were deduced from Doppler shift attenuation and α-γ angular correlation measurements, respectively. Definite spin assignments are: 237 and 2416 keV, $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}$; 1140 keV, $\text{9}\text{2}$^?; 1488 keV, $\text{11}\text{2}$^?; 1825 and 2140 keV, $\text{3}\text{2}$^?. The results for other states below 3 MeV are consistent with the existence of rotational bands (/kh²/2/OI/t~ 95 keV) built on the ($\text{3}\text{2}$⁺) 1817 keV and $\text{1}\text{2}$⁺ 2276 keV hole states. The various measurements together with an earlier value for the lifetime of the first-excited state determine unambiguously the B(M1) and B(E2) values for all of the decay branches of the $\text{7}\text{2}$^?, $\text{9}\text{2}$^? and $\text{11}\text{2}$^? lowest three excited states. From the γ-singles and γ-γ coincidence observations with fusion-evaporation reactions, the yrast cascade proceeds through these three states and higher states at 2957, 3250,3680 and 4139 keV which are suggested to have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{?}}$, $\text{15}\text{2}$^?,$\text{15}\text{2}$^? and $\text{19}\text{2}$^?, respectively. The various experimental results for the $\text{5}\text{2}$^? → ($\text{19}\text{2}$^?) yrast states are in good overall agreement with shell-model calculations in the (f_{$\text{7}\text{2}$}¹ space.     

Evidence for collective oblate rotation in N = Z 68Se

A gamma-ray spectroscopic measurement of the N = Z nucleus 68Se has been made following the 12C(58Ni,2n) reaction at 185 and 220 MeV using Gammasphere and the Argonne Fragment Mass Analyzer. Despite a very low production cross section of 200(50) &mgr;b, two distinct rotational bands were found; the ground state band consistent with oblate collective rotation, and an excited band consistent with prolate rotation. These observations support long-standing predictions that nuclear ground states with substantial oblate (beta(2) approximately -0.3) deformation should exist in this region.     

Ein Beitrag zum Einfluß des Stoffüberganges auf eine erzwungene Konvektion an einer fluiden Phasengrenze

The interfacial-dynamic behaviour of a fluid two-phase-system with mass transfer was investigated under influence of forced convection in the manner of flat jets directed to the interface. The tangential velocities were measured at a characteristic point near to the interface air/water or in the interface itself using a Laser-Doppler-Velocimeter in dependence on the velocities of jets into two phases in both cases with and without transfer of acetone. The variations of velocities due to the interfacial effects are only detectable at small velocities of the jets. They are discussed by model conceptions and compared with the results of a theoretical research of heat transfer in a fluid two-phase-system (Interfacial-dynamic surface renewal model).     

Study of particle and γ decays of the Ex = 12.00 MeV 63+ level in 24Mg

Direct coincidence observation of α- and γ-decays of the E_x = 12.0 MeV level populated in the ${}^{12}\text{C}\text{(}{}^{16}\text{O}\text{, α)}{}^{24}\text{Mg}$ reaction has been used to show that both 6⁺ and 3^? levels exist near this excitation energy. Comparison of the present work with previous radiative capture studies permits the conclusion that the 6₃⁺ level in ²⁴Mg decays primarily by γ-emission, in agreement with recent shell-model calculations using an (sd)⁸ basis. Absolute E2 and M1 strengths deduced from the data are not, however, in good quantitative agreement with the predictions of the shell model.     

Band mixing in light nuclei: Treatment of hole excitations and importance of isospin

Statements in the recent literature regarding the correct treatment of hole states in band mixing calculations are examined and found to be incorrect.     

Failure of the molecular core-particle coupling model in C+C inelastic scattering

The single and mutual inelastic excitation of the predominantly single particle p_1/2 →s_1/2 transition in ¹³C has been studied at energies of 8–25 MeV in the center-of-mass system. The results are in striking disagreement with theoretical predictions made using the molecular particle-core coupling model. It is suggested that intermediate states involving different partitions of the valence nucleons among the cores play an important role in these reactions.