Properties of the 13/2+ isomeric decay in201Hg

The isomeric decay of theT _1/2=94 us isomeric state in²⁰¹Hg was studied in beam via the reaction¹⁹⁸Pt(α, n). Gamma-ray and conversion-electron spectra were recorded. From the conversion coefficients, the multipolarities of the two depopulating transitions were determined to beM 2 + 10%E 3 andE 2, respectively. These assignments give the depopulating transitions to be 13/2⁺ → 9/2^? and 9/2^? → 5/2^?, and these thus substantiate the previous suggestion that the isomeric state hasJ ^π=13/2⁺. For the 13/2⁺ → 9/2^? M 2 transition a detailed study ofE 3 andM 4 admixed amplitudes was done. The microscopic properties of the 13/2⁺ and 9/2^? states are discussed, and a comparison to the corresponding ones in^199,203,205Hg is made.     

Inelastic deuteron breakup followed by fission at intermediate energy

The results of experimental and theoretical studies of the double-differential proton and neutron spectra measured in coincidence with fission fragments in the deuteron-induced reaction on a ²³⁸U target at E _d =65 MeV are presented. These spectra measured in the forward direction are analyzed in the plane-wave Born approximation by using the modified model of stripping into a continuum. The pre-neutron emission fission fragment mass distributions were measured for the (d, f), (d, pf), and (d, nf) reaction channels. The enhancement of highly asymmetric mass division in the (d, pf) channel for the low-energy part of the breakup proton spectrum was observed. The (d, pf) channel can be used to imitate the neutron-induced fission at intermediate energy. The fission characteristics were analyzed in the model taking into account nuclear friction and relevant fission modes.     

Inelastic <Superscript>9</Superscript>Be + α scattering at 90 MeV: Whether the concept of the <Superscript>9</Superscript>Be structure should be changed?

Experimental data on inelastic ⁹Be+α scattering induced by 90-MeV α particles are analyzed. The 2.78-MeV excited state is shown to have spin–parity of I^π=1/2^- in agreement with the existing data. For the 4.70-MeV excited state, it is impossible to make an unambiguous choice between the previous value I^π = 3/2⁺, and the proposed new value I^π = 1/2^?.     

Proton halo in the <Superscript>13</Superscript>N nucleus

We demonstrate that the radii of excited nuclear states can be estimated using the (³He, t) charge-exchange reaction and relying on the modified diffraction model. The radius of the N excited state with an excitation energy of E*=2.73 MeV, which lies in a continuous spectrum, is determined. The radius of this state proves to be close to that of the mirror 3.09-MeV state of the ¹³С nucleus, which possesses a neutron halo but lies in a discrete spectrum. Thereby, we demonstrate that the 2.37-MeV state of the ¹³N nucleus has a proton halo. The analysis is based on published measurements of differential cross sections for relevant reactions.     

Alpha-decay characteristics of neutron-deficient 190Po, 189Bi and 186Pb isotopes

The neutron-deficient ¹⁹⁰Po and ¹⁸⁹Bi isotopes have been produced in the 2n respectively p2n channels of the ⁴⁸Ti +¹⁴⁴ Sm reaction. Cross sections for different reaction channels are given. For ¹⁹⁰Po, improved values of α-energy E_α = 7550(15) keV and half-life T_1/2 = 1.9 _?0.4 ^+0.6 ms were measured. By using correlated α-decay chains an α-branching ratio of 0.50(25) was deduced for ¹⁸⁶Pb. The reduced α-width systematic is extended for both of these isotopes, confirming a persistence of the saturation towards the lighter Po isotopes and the absence of any anomalies for the neutron-deficient Pb isotopes. For ¹⁸⁹Bi improved values of E_α = 7300(15) keV and T_1/2 = 4.8(5) ms were measured.     

Alpha decay of the new isotope 174Hg

Neutron deficient mercury isotopes were produced in the reaction ³⁶Ar + ¹⁴⁴Sm using bombarding energies of 180–230 MeV. 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 (7069±11) keV and (2.1 _?0.7 ^+1.8 ) ms, respectively, was assigned to the new mercury isotope ¹⁷⁴Hg.     

A simple model for a two-stage chemical reaction with diffusion

We analyse the evolution of a two-stage chemical reaction betweentwo neighbouring plumes of reactants. Under the assumption thatthe plumes are approximately Gaussian we derive a system ofordinary differential equations for the total amount, the centroidand the variance of each reactant. We compare the solution ofthese equations with full numerical simulation of the reaction.Excellent agreement is obtained, with solution of the near-Gaussianmodel requiring considerably less computational effort thanthe full simulations. Of key importance is the yield of thereaction, and we discuss this feature in particular.     

Highly excited alpha-cluster states in 34S

The elastic-scattering reaction ³⁰Si + $ \alpha$ was studied using the Thick Target Inverse Kinematics technique. Data were taken at a ³⁰Si beam energy of 150MeV in a reaction chamber filled with ⁴He gas, corresponding to the excitation region of 12-24MeV in ³⁴S . The data were treated in the framework of a simplified R -matrix approach, and energies, widths and spin assignments were obtained for 111 resonances in an approximative manner. The structure is discussed within the concept of $ \alpha$ -cluster structure in the quasi-continuum of ³⁴S and is compared to recent data for ³²S .     

Neutron Structure of the Ground State of 7He

JETP Letters - A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption...