D.W. Miller

Inelastic excitation of normal parity levels in 208Pb by 135 MeV protons

Abstract New cross section data for the inelastic excitation of normal parity levels in 208Pb with spins ranging from J=2 to J =2 are reported. The data are examined in terms of the collective model including deformed spin-orbit coupling. The experimental differential cross sections exhibit a striking transition from central dominated shapes to spin-orbit dominated shapes at J=8.

On the “missing” deep-hole strength in 115Sn☆

Abstract Evidence is found for a “new” deep hole component in 115Sn extending to about 18 MeV excitation and containing most likely 1 f 5 2 strength in addition to 2p strength. With this new component, a better definition of the “background” is possible. All of the combined 1 g 9 2 , 2 p 1 2 , 2 p 3 2 sum rule strength can be accounted for with the inclusion of the new component and the additional overall strength due to the reduced background.

Microscopic description of normal parity excitations in the 208Pb(p, p′) reaction at 135 MeV and the shape of the nucleon-nucleon interaction

Abstract A microscopic study of new 135 MeV inelastic proton scattering data for the excitation of normal parity levels in 208 Pb with spins covering the range J =2 to 10 is reported. The short range repulsion in the central nucleon-nucleon interaction results in small central contributions to the cross sections for the transitions with J =8 and 10.

Possible mesonic effects on inelastic proton scattering to the 10.24 MeV 1+ state in 48Ca

Abstract Differential cross sections and analyzing powers were measured for inelastic scattering of 160 MeV protons to the 48 Ca 10.24 MeV, 1 + state. DWIA calculations with shell-model wave functions which fit inelastic electron scattering form factors predict too much cross section at small q and too little at large q for inelastic proton scattering. These results are consistent with the q -dependent modification of magnetic transitions anticipated from mesonic effects such as virtual Δ (1232)-hole excitations.

Analyzing powers for the proton excitation of high-spin states in 28Si: A new look at the effective interaction☆

Abstract Analyzing powers have been measured for the 5−, T = 0, 6−, T = 0 and 6−, T = 1 high-spin states in 28Si using the inelastic scattering of polarized protons at 135 MeV. These data contain new information on the spin-independent central and the tensor components of the effective nucleon-nucleon interaction at high momentum transfer. The new measurements are in reasonable agreement with distorted-wave impulse approximation calculations.

Deeply-bound hole states in 57Co and the spreading of the 1d52 hole strength distribution

In an attempt to locate the 1d52 proton hole state in 57Co we have measured the 58Ni(d, 3He)57Co reaction with 79.6 MeV vector polarized deuterons. An overall energy resolution of 50 keV was achieved with a magnetic spectrometer. The spectra show fine structure up to Ex = 11 MeV; this fact was used to define energy bins for which cross sections and analyzing powers were obtained. The latter allowed spin and parity assignments for deep-lying hole states in 57Co. Spectroscopic factors were obtained by applying standard DWBA calculations. Most of the strength above 6.6 MeV was identified as being 1d52 in nature. The running sum of Spectroscopic factors shows a linear increase implying a nearly uniform spread of the 1d52 Spectroscopic strength or a width of the 1d52 hole state comparable to the excitation energy.

VECTOR ANALYZING POWERS FOR VALENCE AND INNER SHELL PICKUP IN THE SN-116(D-],T)SN-115 AND SN-116(D-],HE-3)IN-115 REACTIONS

Abstract Differential cross-section and vector analyzing-power angular distributions were measured at Ed = 50 MeV for the 116Sn( d , t)115Sn and 116Sn( d , 3He)115In reactions in the angular range from 6° to 26° for excitation energies up to 25 MeV. In addition to transitions to low-lying states in 115Sn and 115In, data were obtained for the deep-lying hole states in 115Sn. DWBA calculations in general give a good account of the analyzing powers for pickup of the valence shell nucleons. For states at 1.47 MeV (unresolved multiplet) and at 1.65 MeV in 115In, new spin assignments could be made on the basis of the analyzing-power measurements. Analyzing powers for the deeply bound hole states indicate a strong overlap of the different subshell orbitals, although the gross structure peaks still contain characteristic analyzing-power signatures.

Excitation of high-spin unnatural parity states in 208Pb from the (p, p′) reaction at 135 MeV

Abstract Differential cross sections for the excitation of states at 6.42, 6.73 and 7.04 MeV in 208 Pb by 135 MeV protons are reported. Both the excitation energies and the backward peaked angular distributions observed in this experiment and in a recent (e, e′) experiment strongly suggest that these states are predominantly one-particle-one-hole excitations with J π = 12 − , 14 − and 12 − , respectively. The present (p, p′) data are interpreted using a distorted wave impluse approximation and the effect of configuration mixing between the two 12 − states is investigated.

The 116Si(d, p)117Sn l=0 reaction mechanism at intermediate energies

Abstract We report measurements of the cross section, proton polarization, and deuteron vector ( A y ) and tensor ( A yy ) analyzing powers for the 116 S(d, p) 117 )Sn reaction to the 1 2 + ground state of 117 Sn at E d = 79.0 MeV. The polarization was observed as the analyzing power in the time-reversed 117 Sn(p, d) 116 Sn reaction. Adiabatic model calculations of the deuteron elastic channel reveal significant 3 D-wave breakup contributions to the elastic cross section. Satisfactory agreement with the transfer reaction data is nevertheless obtained using adiabatic calculations which include only 3 S -wave breakup and the bound deuteron D-state. The influence of the deuteron spin-orbit distortions on the polarization and vector analyzing power is reduced through a combination of the effects of angular momentum mismatch and deuteron channel absorption.

Implications of far-side dominance for the disagreement between distorted wave theory and well-matched intermediate energy (d, p) reactions

Abstract Distorted wave calculations of large l n -transfer (d, p) reactions near 90 MeV indicate that far-side dominance reduces the number of effective amplitudes at large angles to two or three, making many spin observables redundant. Comparisons of A y with A yy data for 116 Sn(d, p) 117 Sn, and A yy with p y data for 66 Zn(d, p) 67 Zn, do not confirm this expectation.