Alpha-particle scattering from 9Be

The elastic and inelastic scatterings of 35.5 MeV ⁴He ions from ⁹Be are analyzed in the strong coupling limit by the coupled channel method. A good account of the ground-state ($\text{K =}\text{3}\text{2}{}^{\mathrm{?}}$) band is obtained, in agreement with the electromagnetic properties of this band. Data for three states of the $\text{K =}\text{1}\text{2}{}^{\mathrm{+}}$ band are analyzed, yielding much larger isoscalar dipole scattering amplitudes for the $\text{3}\text{2}{}^{\mathrm{+}}$ state than are obtained by electron scattering for electric dipole transitions.     

High-resolution measurements of beta-delayed protons from 37Ca and 41Ti

Protons with energies from 870 keV to 5.4 MeV have been observed following bombardment of a ⁴⁰Ca target with ³He at beam energies of 29.5, 36.5 and 60 MeV, as well as from 40 MeV ³He bombardment of an ³⁶Ar gas target. These data, and those resulting from 20 MeV proton bombardment of ⁴⁰Ca, permit accurate identification of proton unbound levels in ⁴¹Sc, ³⁷K, and ⁴⁰Ca fed by allowed beta decay from ⁴¹Ti, ³⁷Ca or ⁴⁰Sc, respectively. Absolute ft values have been determined for beta decay to these levels. The half-life of ⁴¹Ti has been remeasured to be 80±2 ms and the log ft for its superallowed decay branch has been found to be 3.35±0.02, indicating an isospin purity for the lowest $\text{T =}\text{3}\text{2}\text{state in}{}^{41}\text{Sc of}\text{≈ 91 \%}$. The $\text{ft}\text{values for}{}^{37}\text{Ca}\text{β}{}^{\mathrm{+}}$ decay are compared to shell-model calculations for beta-decay in A = 37 nuclei.     

Backward angle heavy ion elastic on 40Ca and 58Ni

The excitation functions of elastic scattering at 180° for ¹⁶O + ⁴⁰Ca and ¹²C + ⁴⁰Ca are observed to oscillate between $\text{σ}\text{σ}{}_{\mathrm{<mtext>R</mtext>}}\text{= 10}{}^{\mathrm{?3}}$ and 10^?4 over a wide range of energies; the ¹⁶O + ⁵⁸ Ni system shows a monotonic decrease to a value of $\text{σ}\text{σ}{}_{\mathrm{<mtext>R</mtext>}}\text{= 10}{}^{\mathrm{?5}}$ over the energy range studied.     

Two-step processes in the 40Ca(α, 3He)41Ca reaction

The ⁴⁰Ca(α, ³He) reaction has been studied at 36 MeV incident energy. About fifty levels have been observed up to 7.1 MeV excitation energy and angular distributions were measured from 6–60° using a split-pole spectrometer. A local zero-range DWBA analysis has been carried out, and the deduced l-assignments and spectroscopic factors are compared with those obtained from previous neutron stripping experiments. Core-excited states in ⁴¹Ca with a [3^? ? f_7,2], [2⁺ ? f_7,2] and [5^? ? f_7,2] component previously observed in inelastic scattering experiments, are selectively excited by the (α, ³He) reaction. Their angular distributions are compared with coupled-reaction-channel calculations, assuming a pure two-step reaction mechanism. The agreement between theory and experiment may be considered as rather satisfactory for a number of levels. In particular the $\text{1}\text{2}{}^{\mathrm{+}}\text{and}\text{3}\text{2}{}^{\mathrm{+}}$ levels and the high-spin states with $\text{J}{}^{\mathrm{\pi }}\text{=}\text{9}\text{2}{}^{\mathrm{?}}\text{,}\text{11}\text{2}{}^{\mathrm{+}}\text{,}\text{15}\text{2}{}^{\mathrm{+}}\text{and}\text{17}\text{2}{}^{\mathrm{+}}$ are successfully described within the framework of the weak-coupling model.     

Deuteron induced pickup reactions on 41Ca

The ⁴¹Ca(d, t)⁴⁰Ca and ⁴¹Ca(d, τ)⁴⁰K reactions have been investigated at a bombarding energy of 40 MeV. A distorted-wave analysis of the measured angular distributions and a sum-rule analysis of the resulting spectroscopic factors has enabled the identification of members of various particle-hole multiplets. Values obtained for the matrix elements of the $\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^{\mathrm{?}}\text{1}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ effective interaction are in poor agreement with values obtained from other nuclei, but are reasonably well reproduced by calculations with a simple force.     

Spin-parity assignments to high-spin states of 41K and 41Ca

Yrast states of ⁴¹K and ⁴¹Ca have been investigated with the ²⁶Mg(¹⁸O, p2nγ)⁴¹K and ²⁶Mg(¹⁸O, 3nγ)⁴¹Ca reactions at a beam energy of 34 MeV. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization measurements were performed with a Ge(Li)-NaI(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. Unambiguous spin-parity assignments of $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{+}}$, $\text{11}\text{2}{}^{\mathrm{+}}$, $\text{11}\text{2}{}^{\mathrm{?}}$, $\text{13}\text{2}{}^{\mathrm{+}}$, $\text{15}\text{2}{}^{\mathrm{?}}$ and $\text{19}\text{2}{}^{\mathrm{?}}$ to the ⁴¹K levels at E_x = 1.68, 2.53, 2.76, 2.77, 4.27 and 4.98 MeV and of $\text{9}\text{2}{}^{\mathrm{+}}\text{,}\text{11}\text{2}{}^{\mathrm{+}}\text{and}\text{15}\text{2}{}^{\mathrm{+}}$to the ⁴¹Ca levels at E_x = 3.20, 3.37 and 3.83 MeV, respectively, have been obtained. Excitation energies, branching ratios, multipole mixing ratios and transition strengths are reported. The main features of the ⁴¹K and ⁴¹Ca level and decay schemes are reproduced in a 2p-1h and 3p-2h shell-model calculation.     

Nucleon-nucleus optical potential in a relativistic theory of nuclear matter

From a relativistic model of nuclear matter the optical potentials for nucleon scattering from ⁴⁰Ca and ⁹⁰Zr are obtained. These potentials are derived from the properties of the target nucleus and are essentially universal. This means that the integrated strength of the optical potential $\text{J}{}_{\mathrm{A}}\text{= (}\text{1}\text{A}\text{) ∫}\text{d}{}^3\text{r U}{}_{\mathrm{<mtext>op</mtext>}}\text{(r)}$ is very weakly dependent on A. The optical potential for antiparticle-nucleus scattering is also computed.     

Some observations on the differential cross-sections for pp → K−K+

We present Legendre coefficients from fits to the differential cross-sections for $\text{p}\text{p→ K}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}$ in the momentum range 0.8 to 2.4 GeV/c. The s-dependence of the cross-sections at small angles is examined for evidence of Reggeized baryon exchange, and a fit made to this channel and backward K⁺p elastic scattering. Comparisons are made with $\text{p}\text{p→ π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$.     

Electrodisintegration of 3He

Double differential cross sections for electron-³He scattering leading to continuum states were measured between break-up threshold and the region of quasi-free interaction in a momentum transfer range of $\text{1}\text{fm}{}^{\mathrm{?2}}\text{< ¦}\text{q}\text{¦}{}^2\text{< 2.5}\text{fm}{}^{\mathrm{?2}}$. The cross sections for the quasi-free scattering calculated in plane-wave impulse approximation were found to be in good agreement with the experimental results for momentum transfer $\text{¦}\text{q}\text{¦ > 1.5}\text{fm}{}^{\mathrm{?1}}$.     

Observation of weakly coupled 2p-1h states in 41Ca from proton transfer on 40K

The proton transfer on ⁴⁰K has been studied with the ⁴⁰K(³He, d)⁴¹Ca reaction at 13 and 21 MeV bombarding energy and with the ⁴⁰K(d, n)⁴¹Ca reaction at 6.5 MeV bombarding energy. The energy and angular distribution of outgoing particles have been measured. For transitions to 62 levels in ⁴¹Ca the l-values and spectroscopic factors have been derived with DWBA. The excitation energies of levels populated with l = 3 and the qualitative distribution of transfer strength strongly suggest their interpretation as 2p-1h states of the f_{$\text{7}\text{2}$}²d_{$\text{3}\text{2}$}^?1 configuration with weak coupling between the particle pair and the hole. The high-spin states of this configuration (with J^π up to $\text{15}\text{2}{}^{\mathrm{+}}$) are preferentially excited.     

Study of Kπ scattering using the reactions K±p → K±π+nand K±p → K±π−Δ ++at 13 GeV

An elastic Kπ partial-wave analysis is presented. It is based on high statistics data for the reactions $\text{K}{}^{\mathrm{\pm }}\text{p}\text{→}\text{K}{}^{\mathrm{\pm }}\text{π}{}^{\mathrm{+}}\text{n}\text{and K}{}^{\mathrm{\pm }}\text{p}\text{→}\text{K}{}^{\mathrm{\pm }}\text{π}{}^{\mathrm{?}}\text{Δ}{}^{\mathrm{++}}\text{at}\text{13}\text{GeV}$ obtained in a spectrometer experiment performed at SLAC. For each reaction, a t-dependent parametrization of the production amplitudes provides information on both the Kπ mass dependence of the production mechanisms and on Kπ scattering. Knowledge of the t-dependence then allows a calculation of the Kπ partial-wave amplitudes for Kπ masses from 0.7 to 1.9 GeV. The results of such analyses using data for (i) the neutral recoil reactions, (ii) the Δ⁺⁺ recoil reactions, and (iii) both neutron and Δ⁺⁺ recoil reactions simultaneously, are presented. Besides the leading J^P = 1^?, 2⁺, and 3^? resonances at M_Kπ = 0.896, 1.434, and 1.78 GeV, there is evidence in two of the four possible partial-wave solutions for a broad P-wave resonant-like structure in the region of 1700 MeV. The $\text{I =}\text{1}\text{2}$ S-wave magnitude rises slowly and smoothly to a maximum near 1400 MeV, but then decreases rapidly between 1400 and 1600 MeV. This structure is strongly indicative of an S-wave resonance near 1450 MeV. The charge-two Kπ reaction is dominated by S-wave scattering with a total cross section decreasing from 4 mb at 0.9 GeV to 2 mb at 1.5 GeV. Both the $\text{I =}\text{1}\text{2}$ S-wave below 1400 MeV and the $\text{I =}\text{3}\text{2}$ S-wave are well described by an effective range parametrization.     

Experimental analysis of pp interactions between 0 and 1.2 GeV/c: Evidence for a pp → 5π effect near 1950 MeV/c2

An experimental analysis of $\text{p}\text{p}$ interactions between the $\text{p}$p threshold (√s = 1878 MeV) and √s = 2 100 MeV leads to clear evidence for an s-channel effect in the reaction $\text{p}\text{p}\text{→ π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^0\text{at}\text{1949 ± 10}\text{MeV}\text{/c}{}^2\text{(Γ ? 80}\text{MeV}\text{/c}{}^2\text{)}$. A comparison is made with the backward elastic scattering and charge-exchange behaviour. An interpretation in terms of an object strongly coupled to mesonic decay modes, with small or middle-sized elasticity (x ? 0.135_?0.06^+0.13) is given. No significant narrow structure is observed in the backward elastic scattering between 1.9 and 2 GeV. The experimental resolution of √s in this case is 2 MeV.     

Finite-range effects and nonorthogonality corrections in two-step processes of (3He,t) reactions

A full finite-range second order DWBA analysis is made for ⁴⁸Ca(³He, t)⁴⁸Sc at 23 MeV leading to the lowest 0⁺ ～ 7⁺ states of the [$\text{f}{}^{\mathrm{?}}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$] configuration taking into account both ³Heαt and ³He dt two-step processes. The effect of the finite-range of the form factors strongly reduces the contribution of ³Heαt process and the nonorthogonality corrections drastically change the contribution of ³Hedt process. Because of these effects the contributions of both processes have about the same magnitude.     

The interaction of 33 MeV polarised helions with 30Si

Distributions of cross sections and analysing powers have been measured over the range ～ 14°–100° c.m. for the $\text{(}{}^3\text{H}\text{,}{}^3\text{He), (}{}^3\text{H}\text{,}{}^4\text{He), (}{}^{\mathrm{<mtext>3</mtext><mtext>H</mtext>}}\text{,}{}^2\text{H)}$ reactions at 33.4 MeV incident e using a ～ 95 % enriched ³⁰Si target. Phenomenological optical-model analyses of the elastic-scattering data have been carried out. A DWBA analysis of the inelastic-scattering data for the 2.24 MeV (2⁺) and 5.49 MeV (3^?) states of ³⁰Si has yielded values of the deformation β₂ and β₃. The j-dependence of the analysing powers for the (³He, ⁴He) and (³He, ²H) reactions has identified the 6.71 MeV level of ²⁹Si as a $\text{5}\text{2}{}^{\mathrm{+}}$ state, and a level near 9.5 MeV in ³¹P as a possible $\text{7}\text{2}{}^{\mathrm{?}}$ state. Spectroscopic factors for ten states in ²⁹Si and seven states in ³¹P have been deduced and are compared with other work. The extent to which the data defines the ³He spin-orbit potential is discussed.     

Decay of 48K, 49K and 50K

The ⁴⁸K, ⁴⁹K and ⁵⁰K nuclides have been produced in high energy fragmentation and analyzed by mass spectroscopy techniques. Their half-lives have been measured as 6 ± 1 s, 1.1 ± 0.3 s and and 0.7 ± 0.3 s, respectively. The γ-rays from their radioactive decay have been observed and the corresponding γ-intensities measured. The nuclide ⁵⁰K is shown to be a delayed neutron emitter. The antianalog states in the daughter Ca nuclei with a $\text{(1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?}}$ neutron configuration, preferentially populated in the β-decay, have been located. The corresponding $\text{1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ neutron single-particle energy is found to remain approximately constant for these neutron-rich Ca isotopes.     

Elastic scattering of polarised helions from 40,44,48Ca

A phenomenological analysis of the polarised helion elastic scattering data from the ^44,48Ca targets, as well as a re-analysis of the ${}^3\text{He}\text{+}{}^{40}\text{Ca}$ data, has been carried out. It is demonstrated that the spin-orbit potential required to reproduce the polarisation distribution is not unique. Although spin-orbit potentials with the anomalously small diffuseness parameters (a_s ～ 0.2 fm) are found, there are others with larger values (up to 1.05 fm) which can also account for the data in this target mass range. The average strength of the “anomalous” spin-orbit potentials for the three targets is found to be consistent with the values deduced for the proton and deuteron scattering, provided the potential family with the real volume integral per particle pair in the region of 330 MeV · fm³ is considered physically meaningful.     

The 12+ state of 3H and 3He below the break-up threshold: (II). Gammel-Brueckner potential

Results for the $\text{J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$ state of ³H and ³He using the Gammel-Brueckner (GB) nucleon-nucleon potential are presented. Comparison is made with the predictions of the Hamada-Johnston (HJ) potential for bound-state properties and N-d scattering. Whilst the GB potential gives an ³He binding energy at ?7.75 MeV which is close to experiment, the Coulomb energy still remains low. The minimum in the electron scattering charge form factor is in worse agreement with experiment than HJ whilst the secondary maximum shows insufficient enhancement over the HJ results. The N-d doublet scattering length is closer to experiment than the results for HJ but there still appears to be a discrepancy with experiment. These results partially support the suggestion that a two-nucleon potential of HJ type with a larger hard-core radius than HJ, but fitted to a smaller deuteron D-state probability, may give a reasonable representation of the three-nucleon data apart from the Coulomb energy. Evidence now appears strong from this latter parameter for a small charge asymmetry in the two-nucleon potential.     

Neutron diffraction measurement of the Debye-Walker factor of solid hcp 4He

The Debye-Waller factor of hcp ⁴He at molar volumes V_m of 12.06 and 15.72 cm³ has been measured by neutron diffraction techniques. It has been found that for scattering vectors $\text{Q ? 7}\text{A}\text{?}{}^{\mathrm{?1}}$ the Debye-Waller factor can be well represented by a simple Gaussian. The Debye temperatures, appropriate to the Debye-Waller factor, were found to be 99.73 K (V_m = 12.06 cm³) and 55.86 K (V_m = 15.72 cm³). No evidence was found of any forbidden reflections.