Spectroscopy of C

The ¹⁴C(t, p)¹⁶C reaction locates five new states in ¹⁶C, at excitation energies of 3120 ± 15, 3983 ± 10, 4136 ± 10 and 6109 ± 15 keV, in addition to the g.s. and 1.76 MeV states. The 3.02 and 3.98 MeV states appear to be the second 0⁺ and 2⁺ 2p-2h states, respectively. The 4.14 MeV state has J^π = 4⁺ and the 6.11 MeV state has J^π = 2⁺, 3⁻, or 4⁺.     

Studies on the Ne(p, d)Ne and Ne(d, p)Ne reactions

Angular distribution measurements have been performed on the ²¹Ne(p, d)²⁰Ne and ²¹Ne(d, p)²²Ne reactions at E_p = 20 MeV and E_d = 10.2 MeV, respectively. In the ²¹Ne(p, d) ²⁰Ne reaction, the prolific formation of the J^π = 2⁺, 1.63 MeV state was characterized by l_n = 2 pickup, and the distribution associated with the 4⁴, 4.25 MeV state was suggestive of a weak l_n = 2 pickup. All of the observed l_n = 1 pickup strength is associated with formation of the 2⁻, 4.97 MeV ²⁰Ne level. The ²¹Ne(d, p)²²Ne results indicate that l_n = 2 transfer is involved in the formation of the 1.28, 3.36, 5.52, 5.63 and 6.65 MeV ²²Ne states. The angular distribution observed for the 2⁺, 4.46 MeV state and also the unresolved 5.33, 5.36 MeV composite of states required both l_n = 0 and l_n = 2 components in the associated distorted-wave Born approximation fits. The spectroscopic factors extracted from the present results are compared with those predicted by the Nilsson model without mixing: Applications of the angular momentum projection rule to the ²¹Ne(d, p)²²Ne reaction are considered.     

Energy spectra of neutrons emitted following muon capture in O and C

The energy spectra of neutrons emitted following muon capture in ¹⁶O and ¹²C are investigated using the continuum shell model. Nuclear wave functions, which have been shown by Ohtsubo and the author to describe the radiative pion capture reaction in the above nuclei well, are adopted. The calculated neutron energy spectra explain well the observed main peaks, at 5 MeV for ¹⁶O and 4 MeV for ¹²C, which are considered to be the giant resonances excited in the muon capture reaction. These peaks are interpreted as the 2⁻ state at 20.3 MeV for ¹⁶O and the 1⁻ state at 22.5 MeV for ¹²C. Comparisons with photon spectra in radiative pion capture reactions are also made. The calculated total capture rates exceed the experimental values by a factor of 2.5 for ¹⁶O and by 30–40% for ¹²C.     

Study of the structure of S and Ar

The ³⁷Cl(d, ³He)³⁶S and ³⁹K(d, ³He)³⁸ Ar reactions have been studied at a bombarding energy of 28.9 MeV. The results are compared with theoretical calculations for two or four holes in the sd-shell. The three-hole spectrum of ³⁷Cl is also briefly discussed. In the calculation for ³⁸Ar, additional states of a two-particle four-hole nature are included. In ³⁸Ar, the ground state and levels at 2.166 and 7.14 MeV are excited principally by l = 2 transfer, while transitions with appreciable l = 0 strength are observed to levels at 3.935, 4.569, 5.158 and 5.563 MeV. This fragmentation is quite well reproduced by the inclusion of the 2p-4h states. In particular the level at 3.935 MeV is largely of this type, a conclusion supported by both the spectroscopic factors and γ transition rates. The ³⁶S ground state and levels at 6.511 and 7.12 MeV in ³⁶S have angular distributions characteristic of l = 2. Three transitions with l = 0 strength are observed to levels at 3.295, 4.523 and 4.577 MeV in this nucleus. An additional level was identified at 7.71 MeV but the l-transfer could not be determined. The data are only qualitatively reproduced by the four-hole calculation, which while useful in making probable J^π assignments, suggests that core excitation is important here also.     

THE EXCITATION OF 9.5 MeV LEVEL OF 13C IN QUASI-Δ33 DOORWAY STATE MODEL

We have studied the excitation mechanism of 9.5 MeV Level of ¹³C in ¹³C(π^±,π^1±)¹³C (9.5 MeV) inelastic scattering in the framework of Quasi-X33 Doorway State. Model .Assuming. the transition to 9.5 MeV state is of a pure neutron has received satisfactory agreement with experiment. The results strongly suggest that the spin and parity assignment of state,9.5 MeV of ¹³C should be Jπ=9/2⁺.     

Study of Sc states with proton transfer reactions on Ca

The proton transfer reactions (d, n) and (τ, d) on ⁴²Ca have been studied. The reaction ⁴²Ca(d, n)⁴³Sc has been studied by the time-of-flight method at deuteron energies between 5.0 and 6.05 MeV. The reaction ⁴²Ca(τ, d)43Sc has been studied at 18.0 MeV with a magnetic spectrograph. Altogether 54 levels in ⁴³Sc up to an excitation energy of 6.92 MeV have been identified including states at 4.234 and 6.145 MeV which are analogues of the ground state and the 2.048 MeV state respectively in ⁴³Ca. The l-values and spectroscopic strengths have been determined for 31 transitions. Within the errors of the experiments and the DWBA analyses, the spectroscopic strengths derived from the (d, n) and the (τ, d) experiments are in agreement for both and states, i.e. there are no T-dependent discrepancies. Similar agreement is found in the strengths of the s- and d-hole transitions which reflect the degree of particle-hole impurity in the ⁴²Ca_g,s. wave function. A second state is indicated at 2.657 MeV. It appears a likely candidate for the head of a second band of 6p-3h character as proposed by Johnstone.     

Excitation of ΔL = 1 resonances in the (p,n) reaction on Zr, Sn, Ce and Pb at Ep = 41 MeV

A broad peak was systematically observed at about 10 MeV above the Gamow-Teller resonance in the ⁹⁰Zr, ¹²⁰Sn, ¹⁴⁰Ce, ²⁰⁸Pb (p,n) reactions at E_p = 41 MeV. The angular distribution shapes of these peaks support the interpretation that they they correspond to ΔL = 1 state. The data are compared with TDA-DWBA calculations.     

K+ Inelastic Scattering From 2+, 3- State of 12C at 800 MeV/c

The differential cross sections of the inelastic scattering 6f K⁺ at 800 MeV/c on 2⁺, 3^- excited states of ¹²C are calculated by means of the eikonal approximation and the collective coordinate. It seems that the 2⁺ state of ¹²C is quadrupole rotational state, the 3^- state of ¹²C is octupole vibrational state. The results are in agreement with experimental data.     

Spin alignment in resonant C+O inelastic scattering

The spin alignment of the 3⁻ state (6.13 MeV) of ¹⁶O from inelastic scattering of ¹²C+¹⁶O has been measured in the energy region of known resonances around E_cm=20 MeV. The result, that the population of the m=±3 magnetic substates is enhanced on four resonances at 19.7, 20.5, 22.0 and 22.6 MeV, indicates the dominance of the aligned configuration on these resonances.     

Elastic and inelastic scattering of neutrons from Fe and Cu : (I). Measurements from 8 to 14 MeV and a spherical optical model analysis

Differential cross sections were measured at 8, 10, 12 and 14 MeV for elastic scattering of neutrons from enriched samples of ⁵⁴Fe, ⁵⁶Fe, ⁶³Cu and ⁶⁵Cu. Inelastic scattering to the first excited state in ^{54, 56}Fe was also observed. For the ^{63, 65}Cu isotopes, the inelastic cross sections for scattering to the combined group of the three (five) states were determined at 8 and 10 MeV (12 and 14 MeV). The elastic scattering data are compared to predictions of earlier global optical models. New spherical optical model representations were obtained. These data were combined with data for nickel, tin and lead to generate a new global parametrization. Comparisons of derived volume integrals for the potentials, total cross sections and potential radii are made to available information.     

βγ(CP) correlation measurements and anti-analogue structure in the decay of Ca

β-γ(CP) correlation measurements have been carried out on the sequence in the decay of the ground state of ⁴⁹Ca to the (presumed) anti-analogue state at 3.105 MeV excitation in ⁴⁹Sc. An asymmetry parameter of A = −0.132 ± 0.017 was obtained, making any spin-parity assignment other than very unlikely for the 3.105 MeV state. The deduced Fermi matrix element for the decay is |M_{v| = |1.4 ± 9.7| × 10⁻³}, which leads to an isospin impurity ( ) corresponding to the mixing of the analogue state (at 11.6 MeV) and the 3.105 MeV state of ||² 1.6 × 10⁻⁵. This leads in turn to an effective Coulomb matrix element of |H_c| = |3.9 ± 27.4| keV, a low value compared to the value of 100 keV obtained from a theoretical estimate based on simple shell-model wave functions for the single-particle states involved.     

The axial isoscalar neutral current from inelastic electron-nuclear scattering

Parity violating effects due to neutral currents in isoscalar 0⁺→1⁺ nuclear transitions induced by electron scattering are enhanced owing to the small isoscalar magnetic dipole strength. A polarization asymmetry of the order 10⁻⁴ is expected at q 100 MeV for the ¹²C transition to the 1⁺(T = 0) state at 12.71 MeV. It would allow to single out the (electron vector current) × (hardonic axial isoscalar current) quantum numbers and couplings of the neutral current interaction.     

Polarization of protons from the Be(d, p)Be reaction

The polarization of protons from the ⁹Be(d, p)¹⁰Be reaction has been measured for deuteron energies between 1 and 6 MeV. Angular distributions of the polarization for the ground state proton group (Q=4.59 MeV) have been measured for laboratory angles 10° and 135° at 2.5, 4.0 and 5.5 MeV. The polarization at a laboratory angle of 30° was measured in 0.2 MeV steps between 1 and 6 MeV. In addition the polarization of protons leaving ¹⁰Be in its first excited state (Q=1.22 MeV) was measured between 10° and 90° for a deuteron bombarding energy of 5.5 MeV. Measurements were made by conventional double-scattering techniques using elastic scattering from helium at 45° as the analyser. The results show a strong energy dependence contrary to what one might expect on the basis of the lack of structure in the cross section. The maximum polarization observed at each energy is about 0.35.     

Vector analysing power of the pick-up reaction C(d, t)C

The vector analysing power has been measured for the reaction ¹³C(d, t)¹²C initiated by 12.1 MeV polarized douterons and proceeding to the ground and 4.43 MeV states of ¹²C. Large analysing powers were observed especially for the ground state reaction. The results have been compared with the predictions of the distorted waves Born approximation and with data for the ¹²C(d, p)¹³C reaction     

DWBA and CCBA analysis of selected transitions in the C(d,τ) B reaction at Ed = 80 MeV

Angular distribution of the reaction ¹²C(d,τ) ¹¹B leading to the 3/2⁻ ground state and the 4.44 MeV excited (5/2⁻ state ¹¹B have measured at E_d = 80 MeV up to about 70° and 40°, respectively. The inclusion of second-order processes in the framework of CCBA calculations gives a good reproduction of the 3/2⁻ as well as of the DWBA forbidden 3/2⁻ angular distribution. The strong dependence of the cross section on the sign of the deformation supports a positive β₂ value for ¹¹B.     

Prolate and oblate 10 isomers in Sm78 and Gd78

The N = 78 isotones ¹⁴⁰Sm and ¹⁴²Gd have been studied with -particle- and HI-induced reactions. In both nuclei two close-lying 10⁺ isomers at 3.2 MeV have been established, and from the feeding E2 cascades they are characterized as the prolate and the oblate excitations. A third E2 cascade feeding into the ¹⁴²Gd 8⁺ state is interpreted as the continuation of the collective ground state sequence that might assume the properties of a perfect deformed rotor for spins above 10.     

Inelastic electron scattering from He

The spectra of electrons scattered inelastically from ⁴He have been measured at incident energies from 150 MeV to 400 MeV for scattering angles from 38° to 90°. Through the use of a liquid ⁴He target, a high momentum resolution (≈0.25%) was obtained, and the 20 MeV 0⁺ state of the -particle was observed for the first time in electron scattering. The excitation energy and the total width of this state were determined and are in good agreement with the results from other experimental methods. It was found that the total disintegration cross section appears be smaller than 2(σ_p+σ_n) by more than an order of magnitude at the lowest q²(≈ 0.33 fm⁻²). In earlier work the assumption of a total cross section of 2(σ_p+σ_n) was found to be quite accurate for higher q². As a new result, the partial radiative width for the 0⁺ state is determined to be Γ_rad = 1.1±0.3 meV.     

Nuclear excitation effects on heavy-ion scattering

The detailed coupled-channel analysis, including a ground state rotational coupling up to the 4⁺ state, for ¹⁶O scattering from ¹⁵²Sm at the incident-ion energy of 72 MeV is performed. It is found that nuclear excitation plays an important role in the reproduction of details of the observed experimental data, and that the extracted nuclear deformation lengths from this analysis agree with those from light-ion experiments.     

Unconventional Medium Effect in K+-and π+-Nucleus Scattering

The ratios of total cross section of K⁺-nucleus to K⁺-deuterium at 400 MeV/c≤pk≤800 MeV/c for ⁶Li, ¹²C, ²⁸Si, ⁴⁰Ca and the differential cross section of π⁺-¹²C scattering at p_π= 800 MeV/c are calculated by taking into account the unconventional medium effect.An enhancement of both the K⁺-and π⁺-nucleus scattering cross sections is obtained.