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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 cross section and the analyzing powers Ay, Axx, Axz and Ayy for the reaction H ( d , 2 p ) n are studied by kinematically overdetermined measurements at an incident energy of 16 MeV at collinear and somewhat off-collinear kinematic conditions. A three-body Faddeev model using two realistic separable potentials that have different short-range parts gives a good fit to the data. Uncertainties in Coulomb corrections make it difficult to draw definitive conclusions about possible three-nucleon force effects at collinearity conditions.

Quasifree scattering and quasifree reaction processes have been examined in the 3 He+ 2 H → p+d+d, 3 He + 2 H → n+p+ 3 He and 3 He+ 2 H → p+p+t reactions. Beam energies of E d = 22.3 and 35 MeV and of E 3He = 30, 33.5, and 52.5 MeV were used. The experimental results are compared with PWIA calculations and Fourier transforms of the wave functions are extracted. The quasifree processes are described qualitatively by the PWIA, but some features cannot be described by either PWIA or DWIA.

The4He(\(\vec d\),pα)n cross section, vector and tensor analyzing-power data with 12 and 17 MeV deuterons at kinematic conditions including proton-alpha quasifree scattering, neutron-alpha and proton-alpha final-state interactions, as well as collinearity, are compared with the predictions of the three-body model using different nucleon-alpha and neutron-proton forces. In general, better two-body potentials give a better fit to the data, except for the vector analyzing-power data. The roles of the impulse and multiple-scattering amplitudes are studied to understand the sensitivity to two-body potentials and to understand the reason for the successes and the failures of the model.

Quasifree scattering and quasifree reaction processes have been examined in ten 3 H + 3 He and 3 He + 3 He reactions with at least two of the three or more final state particles being charged. Beam energies of 50, 65 and 78 MeV were used. The experimental results are compared with PWIA predictions and Fourier transforms of the wave functions are extracted. The quasifree processes are described in a consistent, but qualitative, manner by the PWIA; distortion in the intial state appears to be the cause of the consistent deviation of the data from the PWIA predictions. Extracted values for the 3 H(d, 3 He)2n cross section are given.

The cross section and the analyzing powers A y , A xx and A yy for the reaction 4 He( d , αp)n are studied with kinematically complete measurements at incident energies of 12 and 17 MeV. Spectral structures due to the final-state interactions and quasifree scattering are measured. A three-body model of the Faddeev type gives a satisfactory fit to the cross-section and A y data, but it fails to fit adequately the tensor analyzing-power data. The tensor analyzing powers in the breakup process should be sensitive to the input two-body force, and that sensitivity seems to be somewhat greater near the three-body 1 + resonance.

A variety of analyzing powers for d + p breakup reactions initiated by polarized deuterons incident on protons have been measured at deuteron bombarding energies of 16 and 79 MeV. The results are compared with Faddeev calculations using both separable (at 16 and 79 MeV) and local (at 79 MeV) interactions. These calculations include nucleon-nucleon forces in the S, P and D states and the 3S1−3D1 tensor force.

The 7 Li (α, t) 8 Be (α) 4 He and 7 Li (α, α') 7 Li ∗ ( t ) 4 He reactions have been observed in a kinematically complete experiment with E α = 50 MeV, particle identification, and on-line computer coincidence electronics. Sequential decay through the ground, 2.9, 11.4, 16.6 and 16.9, and 19.9 MeV states of 8 Be and the 4.63 and 7.48 MeV states of 7 Li has been observed. Triton angular distributions for the decay through the ground state of 8 Be were obtained with and without coincidence requirements. Agreement of these distributions implies isotropic decay in the c.m. of the 8 Be ground state. The contribution of quasi-elastic processes is small due to the specific limited portion of phase space observed.

Approximately seventy resonances were observed for the $^{56}\mathrm{Fe}(p,\ensuremath{\gamma})^{57}\mathrm{Co}$ reaction in the range of proton energy from 1300 to 1800 keV. Gamma-ray energy measurements performed with scintillation and lithium-drift silicon spectrometers yield 6.040\ifmmode\pm\else\textpm\fi{}0.030 MeV for the $Q$ value of the $^{56}\mathrm{Fe}(p,\ensuremath{\gamma})^{57}\mathrm{Co}$ reaction and show the existence of intermediate states in $^{57}\mathrm{Co}$ at 1.381\ifmmode\pm\else\textpm\fi{}0.010, 1.506\ifmmode\pm\else\textpm\fi{}0.020, 1.760\ifmmode\pm\else\textpm\fi{}0.020, 1.921\ifmmode\pm\else\textpm\fi{}0.020, 2.136\ifmmode\pm\else\textpm\fi{}0.020, 2.60\ifmmode\pm\else\textpm\fi{}0.03, 2.74\ifmmode\pm\else\textpm\fi{}0.03, 2.80\ifmmode\pm\else\textpm\fi{}0.03, 2.88\ifmmode\pm\else\textpm\fi{}0.03, 3.11\ifmmode\pm\else\textpm\fi{}0.03, 3.18\ifmmode\pm\else\textpm\fi{}0.03, 3.27\ifmmode\pm\else\textpm\fi{}0.03, and 3.52\ifmmode\pm\else\textpm\fi{}0.03 MeV. Triple-correlation measurements performed with a double sum-coincidence spectrometer permit ${J}^{\ensuremath{\pi}}$ assignments of ${\frac{3}{2}}^{\ensuremath{-}}$, ${\frac{5}{2}}^{\ensuremath{-}}$, ${\frac{5}{2}}^{\ensuremath{-}}$, and ${\frac{5}{2}}^{+}$ to the intermediate states in $^{57}\mathrm{Co}$ at 1.38, 1.76, 1.92, and 2.14 MeV, respectively. These measurements were performed at resonance energies of 1525, 1598, 1622, 1637, 1645, and 1800 keV, where the capturing states at the 1637- and 1800-keV resonances are assigned a ${J}^{\ensuremath{\pi}}$ value of ${\frac{5}{2}}^{+}$, and for the others ${J}^{\ensuremath{\pi}}$ is ${\frac{3}{2}}^{\ensuremath{-}}$. Ambiguities exist for the $\frac{E2}{M1}$ amplitude ratios for all of the mixed secondary gamma-ray transitions observed in these studies. All measurements were in agreement with the established value of ${\frac{7}{2}}^{\ensuremath{-}}$ for the ground state of $^{57}\mathrm{Co}$.

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.

Approximately 50 resonances having a yield of greater than 100 gamma rays per μC were discernible from the 62Ni(p, γ)63Cu reaction in the range of proton energy from 1100 keV to 1850 keV. Gamma-ray energy measurements obtained by utilizing scintillation and lithium-drifted silicon spectrometers yield 3.42±0.02 MeV and 6.14±0.02 MeV for the Q-value of the 58Ni(p, γ)59Cu and 62Ni(p, γ)63Cu reactions, respectively. The existence of intermediate states was observed in 59Cu at 0.49±0.01, 0.91±0.01, 1.38±0.02, 2.00±0.02 and 2.32±0.02 MeV; and in 63Cu at 0.67±0.01 and 1.55±0.02 MeV. Triple-correlation measurements were performed with a double sum-coincidence spectrometer at resonance energies of 1424, 1663 and 1715 keV for the 58Ni(p, γγ)59Cu reaction and at resonance energies of 1374, 1414, 1507 and 1634 keV for the 62Ni(p, γγ)63Cu reaction. These measurements permitted Jπ assignments of ( 1 2 ), 5 2 − , 5 2 − , 5 2 − and ( 3 2 − ) or ( 5 2 − ) to the intermediate states in 59Cu at 0.49, 0.91, 1.38, 2.00 and 2.32 MeV, respectively; and ( 1 2 ) and either ( 3 2 − ) 5 2 − ), or ( 3 2 + ) to the intermediate states in 63Cu at 0.67 and 1.55 MeV, respectively. The E2/M1 amplitude ratios were obtained whenever possible from the correlation data.

The 7 Li (τ, α) 6 Li and 7 Li(τ, α) 6 Li∗(d) 4 He reactions have been used to study the energy levels of 6 Li. Singles spectra provide evidence for five states below 6 MeV of excitation energy. These include the ground state and four excited states at 2.18, 3.56, 4.57 and 5.36 MeV. One- and two-parameter coincidence data confirm the identification of these levels and aid in the determination of decay modes and isospin assignments. The deduced isospin assignments for the five levels are T = 0, 0, 1, 0 and 1 with a small T = 0 impurity, respectively.

The (α, α') and (p, p') reactions have been used to populate states in 24 Mg in order to measure lifetimes of ten states by the Doppler-shift attenuation method. The shifted γ-rays were observed by a planar 5.6 cm 3 Ge(Li) detector at 90° to the beam at the target in coincidence with the scattered particles observed in either of two particle detectors located symmetrically with respect to the beam. A computer coupled dual two-parameter arrangement permitted concurrent measurements for all states appreciably populated. The present measured transition probabilities are compared with predictions from a truncated j - j coupling shell-model calculation.

The α-α angular correlation from the sequential decay of the 11 B(p,α) 8 Be 2.9 (α) 4 He reaction indicates that this reaction proceeds by compound-nucleus formation of 12 C states of E x , J π = 16.11(2 + ), 16.58(2 − and 17.23(1 − ). For E p = 0.163, 0.675, 1.00 and 1.39 MeV, and for a first-emitted α-partiele angle of 90°, kinematically complete experiments provide observed symmetry axes for the 8 Be 2.9 break-up distribution in its own c.m. system. The axis for each correlation function, when compared to the momentum transfer and recoil directions associated with various possible mechanisms, indicates that compound-nucleus formation is the predominating mechanism at each beam energy. The correlation functions at the resonant proton energies of 0.163, 0.675 and 1.39 MeV are consistent with the capture states having J π = 2 + , 2 − and 1 − , respectively.

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)

The alpha induced deuteron breakup reactions have been of interest since the nucleon induced deuteron breakup problem was addressed with tractable and predictive models based on the Faddeev formalism and with appropriate nucleon-nucleon forces. In this paper we discuss a few special features of the alpha induced deuteron breakup reactions. Specifically, we point out the importance of the n-p tensor force in the predictions of the three-body model that fit the tensor analyzing powers better and the concomitant deterioration of the fit to the vector analyzing power caused by the inclusion of the tensor force. We suggest that there exists evidence for the 1S0 n-p interaction, which is isospin forbidden, in both the cross section and spin observables data. Finally, we discuss certain characteristics of the p-? quasi-free-scattering and n-? final-state-interaction processes.