W. Savin

Experimental determination of the signs of E2 interference terms for /sup 192/Os and /sup 194/Pt

The sign of P/sub 3/=M/sub 02/M/sub 22//sub prime/M/sub 02//sub prime/ (M/subr//subs/=-) has been determined by observing interference between one-step and two-step amplitudes for ..cap alpha..-particle excitation of the second 2/sup +/ states of /sup 194/Pt and /sup 192/Os. The sign of P/sub 3/ predicted by Kumar and Baranger is found to be correct for /sup 192/Os but incorrect for /sup 194/Pt. (AIP)

Coulomb--nuclear interference for inelastic deuteron scattering

Abstract The interference between Coulomb excitation and nuclear excitation has been observed for 54, 56 Fe, 60 Ni, 114 Cd, 152 Sm, and 192 Os by measuring excitation functions of elastic and inelastic deuteron scattering at back angles. The interference is strongly constructive, indicating a predominantly imaginary nuclear form factor. DWBA calculations using the collective model, although predicting constructive interference, are unable to predict the magnitude of the observed effect.

Radiative capture of protons by deuterons at Ep = 16 MeV

Abstract The differential cross section for the 2H(p, 3He)γ reaction has been measured at proton energy Ep = 16 MeV. (This energy corresponds to photon energy Eγ = 16.1 MeV in the inverse 3He(γ, d)1H reaction.) The 3He particles were detected by a position-sensitive counter telescope in the focal plane of a magnetic spectrograph. The angular distribution of the reaction was deduced from the measured 3He energy spectrum. The absolute cross section was determined by normalization to concurrent measurements of the 2H(p, p)2H reaction whose cross section is accurately known. Our radiative capture results are compared with other data on this process and its inverse. The present measurements aid in resolving sizable discrepancies between several sets of previous data and thus allow a meaningful comparison with recent theoretical calculations.

NUCLEAR MATTER RADII IN THE TIN ISOTOPES.

Abstract Polarization angular distributions for 16 MeV protons elastically scattered from isotopes of tin have been measured to complement the previously measured 16 MeV proton elastic differential cross-section data of Makofske et al. Standard optical-model analysis of the cross section and polarization data was used to yield nuclear matter rms radii for the isotopes examined. In addition differences between pairs of data sets were examined to determine differences in matter rms radii between pairs of isotopes to an apparent accuracy of better than 0.01 fm. The optical-model analysis combined with existing data on charge radii yielded a separation between neutron and proton rms radius of about 0.5 fm.

Two-hole strengths in 38K from the 39K(3He, α38K reaction

Abstract States in 38K up to 7.13 MeV excitation have been studied using the 21 MeV 3He++ beam of a tandem Van de Graaff and the 39K(3He, α) reaction. Charged particles were analysed by a split-pole magnetic spectrograph equipped with a telescope arrangement of proportional counters for position and energy-loss measurement. Several levels (presumably T = 0) not previously seen in single-nucleon pick-up leading to A = 38 nuclei have been observed. Spectroscopic factors for s 1 2 and d 3 2 or d 5 2 pick-up have b derived using DWBA calculations. Most of the shell-model s 1 2 and d 3 2 strength was observed. The admixtures of s 1 2 −1 d 3 2 −1 and ( d 3 2 ) −2 configurations in states o known spin- from the Spectroscopic factors. Results indicate large 2p-4h admixtures in some states, independent of the ambiguity between d 3 2 and d 5 2 pick-up. The dominance of the l = 0 transition to the 3.42 MeV (2+, 0) state clearly distinguishes among recent realistic shell-model calculations. Observed mixtures of l = 0 and l = 2 strengths disagree with predictions of appreciable d 5 2 strength below 5 MeV.

Neutron correlations in the 41K ground state and T = 1 2p-2h states in 40K

Abstract Differential cross sections have been measured for 41 (d, t) 40 K and 41 K(p, d) 40 K at 15 MeV using a magnetic spectrograph with electronic detection by proportional-counter-scintillator telescopes or semiconductor detectors. Knowledge of the structure of the 40 K multiplets ( ν f 7 2 , π d 3 2 −1 ) and ( ν p 3 2 , π d 3 2 −1 ) permits the determination of amplitudes and relative phases for various configurations and neutron correlations in the 41 K ground state. Spectroscopic factors for neutron pick-up to states in 40 K are strongly influenced by the interference of transition amplitudes. In the (d, t) reaction T = 1, 2p-2h states are also observed.

Particle identification for a position sensitive proportional counter

Abstract A three-counter telescope of about 25 cm active length provides energy and rate of energy loss information for identification of particle type. One counter provides position information after magnetic analysis. Two-dimensional display and curved digital windows select particles of various types.

The phase and shape of the form factor for inelastic 3He scattering

Abstract Interference between nuclear and Coulomb excitation of the 0.56 MeV 2 + state of 114 Cd by 3 He particles with energies near the Coulomb barrier has been observed. The results indicate that the collective model describes the data well and that the form factor for inelastic 3 He scattering is therefore largely imaginary.

Sensitivity of (α, α′) cross sections to excited-state quadrupole moments

Abstract Angular distributions for excitation of the 1.20 MeV second 2+ state in 180Hf by 21 and 24 MeV α-particles have been measured. Coupled-channels calculations show substantial sensitivity to the assumed quadrupole moment of this state. The data are best-fitted by calculations using the value of the quadrupole moment expected if the state is a simple λ-vibrational level.