S.E. Vigdor

Study of the reactions 118Sn(d, t) and 98Mo(d, t): (I). Spectroscopy of 117Sn and 97Mo

Abstract The vector analyzing power and differential cross section have been measured at a deuteron energy of 12.0 MeV for 118 Sn ( d , t ) transitions to six states of 117Sn (Ex = 0.0, 0.16, 0.31, 0.71, 1.02 and 1.18 MeV), for 98 Mo ( d , t ) transitions to eight states of 97Mo (Ex = 0.0, 0.68, 0.72, 0.89, 1.12, 1.28, 2.39 and 2.52 MeV), and for 118 Sn ( d , d ) and 98 Mo ( d , d ) . Deuteron optical model potentials were obtained from analysis of the elastic scattering measurements, and were used in a DWBA analysis of the ( d , t ) results. Comparison of the measurements and DWBA predictions for σ(θ) and for iT11(θ) allows unambiguous determination of tln and jn for all 118Sn(d, t) and most 98Mo(d, t) transitions. Differences in the triton energy relative to the Coulomb barrier cause marked qualitative differences in the measured cross sections and analyzing powers between 118 Sn ( d , t ) and 98 Mo ( d , t ) transitions of the same ln and jn.

Study of the reactions 208Pb(d, p) and 208Pb(d, t) near the coulomb barrier

Abstract The vector analyzing power and differential cross section have been measured at a deuteron energy of 12.3 MeV for 208 Pb ( d , p ) , transitions to seven states of 209 Pb ( E x = 0.0, 0.79, 1.42, 1.56, 2.01 and 2.47+2.51 MeV, for 208 Pb ( d , t ) transitions to three states 207 Pb ( E x = 0.0, 0.57 and 0.89 MeV), and for 208 Pb ( d , d ) . Two deuteron optical model potentials were obtained from analysis of the elastic scattering measurements, and were used in a DWBA analysis of the present transfer-reaction results and of previous results for 207 Pb ( d , p 0 ) 208 Pb . The sensitivity of the DWBA analysis to the nuclear interior is investigated. The relative importance of Coulomb and of nuclear distortions is discussed. The sign of the vector analyzing power for given l n depends on j n and on Q -value for both the ( d, p ) and the ( d,t ) reactions. The Q -dependence invalidates the simple rule proposed by Griffith and Roman to relate j n to the predominant sign of iT 11 . Comparison of the measurements and DWBA predictions for iT 11 ( θ ) allows unambiguous determination of j n for all transitions except 207 Pb ( d , p 0 ) . All spins determined in the present work confirm previous assignments. The vector analyzing powers for the 208 Pb ( d , t 0 ) 207 Pb and 207 Pb ( d , p 0 ) 208 Pb transitions are observed to be similar in angular dependence but opposite in sign at all angles. The sign reversal reflects differences in the distortions of the proton and triton waves.

Evidence for Two-Nucleon Processes in A(p,Pi-)A+1

Possible signatures of two-nucleon pion production processes in reactions A(p/sub pol/,..pi../sup -/)A+1 near threshold are identified: a dependence of the analyzing power on the total angular momentum, and a simple scaling of the cross section with subshell occupancy for the struck target neutron. Measurements for /sup 12,13,14/C(p/sub pol/,..pi../sup -/) exhibit these expected features, supporting the view that the fundamental NN..-->..NN..pi.. processes dominate in nuclear pion production.

Semi-classical interpretation of the vector analyzing power in sub-coulomb neutron-transfer reactions

Abstract Sub-Coulomb neutron-transfer reactions are considered in a classical model in which the incident and outgoing projectiles follow Coulomb scattering trajectories with coincident turning points. The dependence of the vector analyzing power on bombarding energy and Q-value, and the angular dependence of the cross section are explained. The sign of the analyzing power is related directly to the total angular momentum transfer. Predictions of the model for ( d , p ) and ( d , t ) reactions are compared with DWBA calculations employing only Coulomb distortions. Limitations of the model are discussed.

Evidence for two-nucleon processes in A(p/sub pol/,. pi. /sup -/)A+1

Possible signatures of two-nucleon pion production processes in reactions A(p/sub pol/,..pi../sup -/)A+1 near threshold are identified: a dependence of the analyzing power on the total angular momentum, and a simple scaling of the cross section with subshell occupancy for the struck target neutron. Measurements for /sup 12,13,14/C(p/sub pol/,..pi../sup -/) exhibit these expected features, supporting the view that the fundamental NN..-->..NN..pi.. processes dominate in nuclear pion production.

Study of the reactions 118Sn(d, t) and 98Mo(d, t): (II). Interpretation of the ln = 0 results

Abstract Measurements of the vector analyzing power at E d = 12.0 MeV for l n = 0 transitions in 118 Sn ( d , t) and 98 Mo ( d , t ) 97 Mo are examined. A DWBA analysis reveals that the ( d , t ) analyzing powers are sensitive to the deuteron-nucleus, but not to the triton-nucleus spin-orbit interaction. For the ground-state transition 118 Sn ( d , t 0 ) 117 Sn , an unexpectedly strong correlation is observed between the measured analyzing power and the logarithmic derivative with respect to angle of the measured differential cross section. The correlation is shown to arise in part because the radial wave functions corresponding to a given partial wave penetrate considerably further in the deuteron channel than in the near-Coulomb triton channel. Under the conditions responsible for this correlation, the radius parameter of the deuteron-nucleus spin-orbit potential can be estimated directly from the ( d , t ) analyzing power measurements, in a manner independent of optical model analyses of deuteron elastic scattering. We also investigate the origin of correlations between the l n = 0 analyzing power and that for deuteron elastic scattering from the same target nucleus, and between the analyzing powers for the reactions 118 Sn ( d , t 0 ) 117 Sn and 117 Sn ( d , p 0 ) 118 Sn .

Roper excitation inp→+α→p→+α+Xreactions

We calculate differential cross sections and the spin transfer coefficient

Oscillations in the excitation function for complete fusion of /sup 16/O+/sup 12/C. [13-27 MeV]

D_{nn}

Dominance of high-spin two-particle--one-hole transitions in ( p,. pi. /sup -/) reactions

in the

Measurement of the Branching Ratio for the Decay η → μ+μ-

\vec{p}+\alpha \to \vec{p}+\alpha+\pi^0