Analysis of scattering and reactions of aligned7Li-nuclei in a double folding model

Previously measured angular distributions of the differential cross section and the tensor analyzing powerT ₂₀ for the scattering of⁷Li from⁵¹V in the energy range from 10 to 18 MeV were analyzed with the double folding model using the effective nucleon-nucleon interaction M3Y as well as a zero range effective nucleon-nucleon interaction. Due to the spectroscopic deformation of the⁷Li-nucleus the interaction potential contains a central and aT _R -tensor part. The latter one is the origin of the observed tensor analyzing powers. Within the same model the scattering of aligned⁷Li-nuclei from⁵⁸Ni at 14.2 and 20.3 MeV is well described. The strength of theT _R -tensor potential in relation to the spectroscopic mass deformation of⁷Li is discussed. Using the real interaction potential obtained by the double folding model the energy dependence of the total reaction cross sectionσ ^r and its tensor analyzing powerT ₂₀ ^r for the system⁷Li?⁵¹V is well described within a barrier penetration model.     

Evidence for a real tensor potential in the inelastic scattering of 800 mev polarized protons from20ne using the dirac phenomenology

Coupled-channel calculations using the Dirac phenomenology have been performed to analyze cross-sections and analyzing powers data for inelastic scattering of 800 MeV, polarized protons from low-lying states in²⁰Ne. Good agreement with the data has been obtained by using a real tensor potential V _t ^r =27.02 MeV, in addition to real scalar potential and complex vector potential. Deformation parameters obtained at this energy of 800 MeV are very close to those obtained at an energy much lower (24.5 MeV). Once more, considerable improvements obtained by using Dirac equation, compared to Schrödinger calculations, are confirmed. The calculations are also consistent with V _s ⁱ =0.     

Coupling effects of resonant and discretized non-resonant continuum states in4He +6Li scattering at 10 MeV/A

Alpha- particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of⁶Li is studied at incident energy 10 MeV/A. Theα+d breakup continuum part within the excitation energyE _ex=1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

Elastische und inelastische Streuung von 104 MeV Alpha-Teilchen an58,60,62,64Ni

Differential cross sections are measured for the elastic and inelastic scattering of 104 MeV α-particles from^{58, 60, 62, 64}Ni. The experimental results are analyzed in terms of coupled channels on the basis of an anharmonic vibrational model and prove to be quite sensitive to the values of the deformation parameters. For forward angles the 4⁺ angular distributions of^58,60Ni are dominated by aL=4 single excitation mechanism. This is in keeping with theE4-transitions observed in (e, e′) scattering. From the 2 ₁ ⁺ - and 3 ₁ ⁺ -results transition rates are derived which can be compared to results of electromagnetic methods and of inelastic proton scattering studies. The comparison indicates that the transition rates differ and are generally higher for the proton scattering. Especially in the case of the 3^? states of^58,60Ni the differences are obvious. The elastic cross sections are analyzed both on the basis of the usual phenomeno-logical model and in terms of a semimicroscopic folding model resulting in values of rms-radii for the nuclear matter distribution.     

The new isotopes258105,257105,254Lr and253Lr

Evaporation residues from the heavy-ion fusion reaction⁵⁰Ti on²⁰⁹Bi were investigated. They were separated from the projectile beam by the velocity filter SHIP and identified after implantation into an array of position-sensitive surface-barrier detectors by analyzing theirα-decay chains. Spontaneous fission was also observed. Four newα emitters,²⁵⁸105 (T_1/2=4.4 _?0.6 ^+0.9 s),²⁵⁷105 (T_1/2= 1.4 _?0.3 ^+0.6 s),²⁵⁴Lr (T _1/2= 13 _?2 ⁺³ s), and²⁵³Lr (T _1/2=1.3 _?0.3 ^+0.6 s) could be identified. For the isotope²⁵⁷105 we obtained a spontaneous-fission branch of about 20%. A spontaneous-fission activity with a halflife comparable to that for theα decay of²⁵⁸105 was explained as fission of²⁵⁸104, formed by electron capture from²⁵⁸105. An excitation function for evaporation-residue production was measured for bombarding energies in the range ofE _CM=184.4 MeV toE _CM=196.6 MeV. Nearly all evaporation residues we observed, could be attributed to the 1n and 2n deexcitation channels. The maximum cross sections wereσ(1n)=c/2.9±0.3) nbarn, andσ(2n)=c/2.1±0.8) nbarn, respectively. We could measure the total kinetic energy of the fission fragments of²⁵⁸104 to be TKE=(220±15) MeV, a value that fits into empirical systematics based on aZ ²/A ^1/3 dependence.     

Resonance strengths,branching ratios and mean lifetimes of nuclear energy levels in23Na

The gamma decay of the²²Ne(p, y)²³Na resonances in the proton energy rangeE _p=1.0→2.0 MeV has been investigated with a 20cm³ Ge(Li) detector. Implanted targets were used. The absolute strengths of the strongest resonances were determined and the branching ratios of twenty resonance levels and several bound states are reported. Mean lifetimes of the levels atE _x=2.078 MeV (18.7±3.5 fs), 2.393 MeV (580 _?190 ⁺³⁷⁰ fs), 2.641 MeV (88 _?14 ⁺²⁰ fs), 2.985 MeV (4.0 _?1.0 ^+1.3 fs), 3.679 MeV (24 _?4 ⁺⁵ fs), 3.915 MeV (7.4 _?2.0 ^+2.5 fs) and 4.775 MeV (<2.0 fs) were obtained from measurements of the gamma ray Doppler shifts.     

Off-shell effects in nucleon-deuteron polarization observables

A separable representation of theS-wave Paris potential and a phase-shift equivalent Yamaguchi-type potential significantly differing in their off-shell behaviours are used to calculate second-order polarization observables of elastic nucleon-deuteron scattering atE _D=10 and 20MeV. Off-shell effects are found that stem from differences in the nuclear interaction in the inner regionr?1.2 fm. Adding approximate Coulomb-distortion contributions to the purely nuclear Faddeev amplitudes proton-deuteron predictions are obtained. Coulomb effects are not found to be negligible. Comparison with experimental data, in particular, the spin-correlation parameterC _y,y of the reaction \({}^1\vec H(\vec d,d)^1 H\) forE _D=10MeV vector-polarized deuterons and the spin-transfer coefficientsK _y ^y′ ,K _x ^x′ andK _z ^x′ for \({}^2H(\vec p,\vec p)^2 H\) atE _p=10MeV, prefer the interaction model that contains an intermediate-range repulsion.     

Coupling effects of resonant and discretized non-resonant continuum states in 4He + 6Li scattering at 10 MeV/A

Alpha-particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of ⁶Li is studied at incident energy 10 MeV/A. The α + d breakup continuum part within the excitation energy E _ex = 1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

g-factor of the second 4+ state in24Mg

The transient field technique has been used to determine theg-factor of the 4 ₂ ⁺ state at 6.010MeV excitation in²⁴Mg. The deduced value ofg=+0.5(4) is consistent with collective model expectations. Further, the equality within experimental accuracies, of the g-factors of the 2 ₁ ⁺ , 2 ₂ ⁺ , 4 ₁ ⁺ and 4 ₂ ⁺ states agrees with theoretical predictions for thisT=0 self-conjugate nucleus, in contrast to the results for²⁰Ne.     

Energy dependence of tensor analyzing powers in deuteron elastic scattering from 208Pb

Differential cross section and all four analyzing powers iT₁₁, T₂₀, T₃₁ and T₂₂ have been measured for deuteron elastic scattering from ²⁰⁸Pb at incident energies from 10 to 23 MeV. The energy dependence of the tensor analyzing powers was investigated. A considerable deviation of the data from optical-model calculations including a T_r-type tensor potential is found near the Coulomb barrier.     

Differential analyzing power in pp′ scattering on a 28Si nucleus in the case of the excitation of high-spin particle-hole states

The experimental energy dependence of the differential analyzing power for 5 ₁ ^? , T=0 and 6 ₁ ^? , T=1 levels in the ²⁸Si nucleus is compared with the results of the calculations based on the DWBA-91 code. Information obtained for the nuclear structure from an analysis of inelastic scattering is discussed.     

Decay energy of183Re→183W

The electron capture decay energy of¹⁸³Re has been determined from the fraction ofK-capture in the transition to the 453.08 keV level in¹⁸³W by delayed coincidences. From this value the total decay energy from₁₈₃Re→¹⁸³W is obtained to beQ=555 _?7 ⁺⁹ keV according to the theory ofBrysk andRose with corrections ofBahcall. The resulting logft values and consequences for the decay scheme are discussed.     

Nuclear spin relaxation of Xe in liquid Te

By the method of time differential perturbed angular distribution following a nuclear reaction, the relaxation rateT _r ^?1 of the 8 msI ^π=10⁺ isomer of¹³²Xe has been measured in liquid Te. Between 670 °K (supercooled liquid) and 1,000 °K the rate decreases from about 720/s by about a factor of two. From existing experimental material it is concluded thatT _r ^?1 is mainly due to quadrupolar interaction (T _r ^?1 ≈T _Q ^?1 ). Its magnitude is discussed considering the metallic and the noble gas limit as models for the Xe-Te-interactions. The temperature dependenceT _Q(T) apparently does not correlate with the diffusion constant of Te in contrast to a simplified theoretical treatment. — The nuclearg value of the isomer has been determined to be g=(?)0.195(5) thus confirming the configuration (vh_11/2)².     

Discovery of deeply bound π− states in the208Pb(d,3He) reaction

Narrow lines were observed around 133 MeV excitation energy in the²⁰⁸Pb(d,³He) reaction atT _d=300 MeV/u using the Fragment Separator System at GSI. They are assigned to the deeply boundπ ^??²⁰⁷Pb states with configurations of $\left( {2p} \right)_{\pi ^ - } $ (3p_1/2, 3p_3/2) _n ^?1 .     

Identification of180Pb

Theα decay of the new isotope¹⁸⁰Pb was observed in⁴⁰Ca bombardments of¹⁴⁴Sm:E _α = 7.23(4)MeV, and,T _1/2=(4 _?2 ⁺⁴ )ms. With this decay energy and the known mass of¹⁷⁶Hg, the mass excess of¹⁸⁰Pb was calculated to be ?1.98(5)MeV.     

Untersuchung der vier ersten angeregten Zustände des6Li-Kernes durch Elektronenstreuung

Inelastic electron scattering cross sections were measured for energies below 60 MeV and momentum transfersq between 0.2 and 0.6 fm^?1. Ground state radiative widths Γ _γ ⁰ and transition radiiR _tr were deduced. 2.18 MeV: Γ _γ ⁰ (E2)=(4.40±0.34) · 10^?4 eV,R _tr=(4.28±0.39)fm; 3.56MeV: Γ _γ ⁰ (M1)=(8.31±0.36)eV,R _tr=(2.90±0.10)fm; 4.27 MeV: Γ _γ ⁰ (E2)=(5.4±2.8) · 10^?3 eV,R _tr=(3.4±1.2) fm. The excitation of the 5.37 MeV level shows a transverse angular dependence.     

Temperature dependence of the damping width of single-particle states in hot nuclei

The temperature dependence of the damping widthΓ _sp ^↓ of single-particle levels of atomic nuclei is calculated as a function of temperature T. It is found thatΓ _sp ^↓ displays a linear dependence with temperature in the range 0.5 MeV≤T≤3 MeV.     

Spectroscopy of50V with (p,nγ) reaction

Information on the low-lying levels up to ～1.9 MeV excitation of the doubly odd nucleus⁵⁰V has been obtained through the Ge (Li)-Ge (Li) coincidence study with the⁵⁰Ti(p, nγ)⁵⁰V reaction. Branching ratios have been measured and tentative spin-parity assignments have been made. A detailed comparison with other measurements reported recently has also been made. Using the lowest seniority wave functions with (f_7/2) _p ³ (f _7/2) _n ^?1 configuration, energy levels and electromagnetic properties have been calculated. These have been compared with the present and earlier experimental data.     

ΛΛ 6 He and Λ 9 Be systems in the three-body cluster model treated on the basis of differential Faddeev equations

The _ΛΛ ⁶ He and _Λ ⁹ Be hypernuclei are treated as the S=0, T=0 (for the former) and S=1/2, T=0 (for the latter) bound states of the three-cluster systems ΛΛα and Λαα, respectively. The cluster-reduction method is used to solve the s-wave differential Faddeev equations for these systems. On the basis of the MT I–III model, the ΛΛ interaction potential is specified in the form $V_{\Lambda \Lambda } = \frac{2}{3}V_{NN} $ . Phenomenological potentials are used to describe Λα and αα interactions. The binding energies of the _ΛΛ ⁶ He and _Λ ⁹ Be hypernuclei and the parameters of low-energy Λ-hyperon and α-particle scattering on a _Λ ⁵ He hypernucleus are calculated. It is shown that the proposed ΛΛ interaction potential makes it possible to reproduce faithfully the binding energy of the _ΛΛ ⁶ He hypernucleus and that scattering in the Λ _Λ ⁵ He system is similar to neutron scattering on a deuteron.