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The present paper identifies unique symmetry properties of the [ital [rvec d]]+[ital d][r arrow][ital d]+[ital p]+[ital n] breakup reaction that make it an excellent probe for studying charge-symmetry breaking. Measurements were made for two configurations of the ejected particles in the breakup reaction to obtain values of the spin observables [ital A][sub [ital y]], [ital A][sub [ital y][ital y]], and [ital A][sub [ital z][ital z]]. These observables are compared for the mirror reactions [sup 2]H([ital [rvec d]],[ital dp])[ital n] and [sup 2]H([ital [rvec d]],[ital dn])[ital p] for the two angle pairs ([theta][sub [ital d]],[phi][sub [ital d]],[theta][sub [ital N]],[phi][sub [ital N]])=(17.0[degree],0[degree],17.0[degree],180[degree]) and (17.0[degree],0[degree],34.5[degree],180[degree]) for an incident deutron energy of 12 MeV. In addition, spin observables for the [sup 2]H([ital [rvec d]],[ital pn])[ital d] reaction at [theta][sub [ital p]]=[theta][sub [ital n]] and [phi][sub [ital p]]=[phi][sub [ital n]]+180[degree] are shown to provide a particularly good test of charge symmetry. Our [ital A][sub [ital y]], [ital A][sub [ital y][ital y]], and [ital A][sub [ital z][ital z]] data for the [sup 2]H([ital [rvec d]],[ital pn])[ital d] reaction at ([theta][sub [ital p]],[phi][sub [ital p]],[theta][sub [ital n]],[phi][sub [ital n]])=(17.0[degree],0[degree],17.0[degree],180[degree]) are used to illustrate this latter point. Of the ten charge-symmetric sets of observables measured, two were foundmore » to differ by 2.5 standard deviations.« less

Experimental and theoretical cross sections are presented for the /sup 6/Li(/sup 3/He,/sup 3/He/sup 3/He)/sup 3/H and /sup 6/Li(/sup 3/He,t/sup 3/He)/sup 3/He reactions for the symmetric angle pairs 20/sup 0/-20/sup 0/, 28.3/sup 0/-28.3/sup 0/, and 35/sup 0/-35/sup 0/. The theoretical cross sections are calculated in a three-body model where the trions (i.e., mass-3 nuclei) are treated as elementary particles with /sup 6/Li being a /sup 3/He-/sup 3/H bound state. The trion-trion interaction is represented by S wave separable potentials with the breakup cross sections calculated with the tree-body Haftel-Ebenhoeh code. the Coulomb interaction is taken into account by fitting the separable potential parameters to the trion-trion scattering data and is included approximately in the breakup code. The experimental cross sections are compared with both the plane-wave impulse approximation and the three-body model predictions. The plane-wave impulse approximation predicts both the shapes and magnitudes poorly (10 to 20 times experiment). Without Coulomb corrections the three-body model gives good agreement with experiment for the shapes of the spectra with the magnitudes generally being about 40% of experiment for /sup 6/Li(/sup 3/He,/sup 3/He/sup 3/He)/sup 3/H and about 80% for /sup 6/Li(/sup 3/He,t /sup 3/He)/sup 3/He. The Coulomb corrections improve the magnitudes predicted by themore » three-body model but not the shapes. It is observed that for these reactions S wave separable potentials describe the breakup data much better than they do the two-body trion-trion scattering data. This result should encourage further three-body treatment of these and similar reactions.« less

The quasielastic scattering of 50-MeV $\ensuremath{\alpha}$ particles has been used as a tool to study the cluster configurations of the $^{6}\mathrm{Li}$ nucleus by means of the $^{6}\mathrm{Li}(\ensuremath{\alpha},\ensuremath{\alpha}x)Y$ reaction. Data have been obtained in kinematically complete experiments and at exact quasielastic angles for those cases corresponding to $x=p, d, t$, He, and $\ensuremath{\alpha}$. Analysis has been carried out in the framework of the plane-wave impulse approximation. Quasielastic cross sections have been measured and experimental momentum distributions extracted. Theoretical fits to these distributions using simple Gaussian and exponential functions have been calculated and used to determine both absolute and relative clustering probabilities with fair success. The more reliable relative probabilities indicate strong $p, d$, and $\ensuremath{\alpha}$ clustering in $^{6}\mathrm{Li}$ and rather weak $t$ and $^{3}\mathrm{He}$ clustering.

The $sup 2$H(p,2p)n reaction has been investigated under the special kinematic condition that the neutron is at rest in the center of mass. A comparison of experiment and theory is used to examine the significance of the spectral structure observed for such collinearity conditions. (AIP)