Cross-section measurements of seven exit-channel configurations in the neutron-deuteron breakup at 13.0 MeV are reported and compared to rigorous calculations. Our data are consistent with those of previous measurements in four of six configurations. The present data for five configurations are in good agreement with theoretical predictions. The cross-section data for the space-star and another out-of-plane configuration are larger than the theoretical predictions by more than three standard deviations. The previously observed 20% discrepancy between theory and data for the space-star configuration is confirmed in the present work. The inclusion of the Tucson-Melbourne 2 pi-exchange three-nucleon force changes the predicted cross section by only 2% and in the wrong direction needed to bring theory into agreement with data.

Cross-section measurements of a collinear configuration, the space-star and the coplanar-star configurations in nd breakup at En = 13.0 MeV are reported. The present measurements for the collinear configuration are in good agreement with pd and nd data. Our coplanar-star data are consistent with theoretical predictions and resolve the reported problem with this configuration. The previously observed large discrepancy between theory and nd cross-section data for the space-star configuration is confirmed in the present work.

We report the most extensive set of vector iT(11) and tensor T-20 and T-22 analyzing-power data for the (d) over right arrow+d-->d+p+n reaction. Two-particle coincidence data have been measured for six deuteron-proton, three deuteron-neutron and three proton-neutron angle pairs at an incident deuteron energy of 12.0 MeV. These data are compared to impulse-approximation calculations that treat the underlying nucleon-deuteron system exactly and include contributions from both target and projectile breakup processes. This model gives a good description of the analyzing-power and relative cross-section data. We show that the inclusion of nucleon-nucleon P interactions considerably improves the agreement with the spin observables. The disagreement between the data and theoretical predictions show the limitations in our model and the importance of the rescattering processes. We suggest that the d+d three-body breakup process will provide useful information on the nucleon-nucleon force when exact calculations become available.

Results of our recent kinematically complete cross-section measurements of the space-star and coplanar-star configurations in n-d breakup at 13.0 MeV are reported. The experimental setup and details of the analysis are described. The new data for the space-star configuration are in good agreement with previous n-d data but differ significantly from both “exact” n-d calculations and p-d data. In constrast, the new coplanar-star data are in fair agreement with the calculations but are in gross disagreement with previous n-d data. The implications of these data for three-nucleon forces are discussed.

The present paper identifies unique symmetry properties of the d --> + d --> d + p + 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 A(y), A(yy), and A(zz). These observables are compared for the mirror reactions H-2(d -->, dp)n and H-2(d -->, dn)p for the two angle pairs (theta(d), phi(d), theta(N), phi(N)) = (17.0-degrees, 0-degrees, 17.0-degrees, 180-degrees) and (17.0-degrees, 0-degrees, 34.5-degrees, 180-degrees) for an incident deuteron energy of 12 MeV. In addition, spin observables for the H-2(d -->, pn)d reaction at theta(p) = theta(n) and phi(p) = phi(n) + 180-degrees are shown to provide a particularly good test of charge symmetry. Our A(y), A(yy), and A(zz) data for the H-2(d -->, pn)d reaction at (theta(p), phi(p), theta(n), phi(n)) = (17.0-degrees, 0-degrees, 17.0-degrees, 180-degrees) are used to illustrate this latter point. Of the ten charge-symmetric sets of observables measured, two were found to differ by 2.5 standard deviations.

Measurements of the analyzing power ${\mathit{A}}_{\mathit{y}}$(\ensuremath{\theta}) for neutron-proton scattering have been performed at 7.6, 12.0, 14.1, 16.0, and 18.5 MeV. The experimental setup is described as are the finite-geometry corrections applied to the data. One of these corrections, due to the presence of carbon in the scintillators used for neutron detection, is discussed in detail. The ${\mathit{A}}_{\mathit{y}}$(\ensuremath{\theta}) data are compared to the predictions of the Paris and Bonn nucleon-nucleon potentials and the predictions of two phase-shift analyses, one of which incorporates charge-independence breaking effects in the $^{3}$P waves.

In this paper we review the results of a series of high-accuracy measurements on the neutron-deuteron (n-d) scattering system at incident neutron energies below 20 MeV. These measurements were designed to: 1) provide data of sufficient accuracy to be used to refine the parametrization of the nucleon-nucleon force, 2) to test the reaction dynamics in the “rigorous” calculations of three-nucleon (3N) breakup reactions, and 3) identify 3N scattering observables that are specifically sensitive to three-nucleon forces and/or off-shell effects. At TUNL we have measured vector analyzing powers Ay (θ) for n-d elastic scattering and the breakup reaction to an accuracy better than ± 0.005 and ± 0.020, respectively. Recent results on items 1) and 2) will be presented. Also, results of cross-section measurements for n-d and p-d breakup will be compared to a “rigorous” 3N calculation.

EVOLVE simulation results of sputtering processes of Au films with 175 keV Ar ions are compared to available experimental results. Thicknesses of Au films are 23, 99 and 192 nm, which are small, comparable and large, respectively, compared to the range of Ar ions. As a result of dose-dependent analysis of Au films, a good agreement has been found if the displacement threshold energy of Au is assumed to be 12 eV. Reducing the surface binding energy of Au from 3.8 to 1.9 or even to 0.0 eV does not increase the sputtering yield as the elemental sputtering yield formula predicts. In fact, it has no significant effect at all on the sputtering yield if the elemental value, e.g. 36 eV, is used for the displacement threshold energy of Au. On the other hand, reducing the displacement threshold energy from 36 to 12 eV increases the sputtering yield by more than a factor of 2. The sputtering yield is expressed and discussed in terms of parametric relationships of the surface binding energy, displacement threshold energy, the film thickness and the fluence.

Neutron-Proton A(y) (theta) measurements have been made t 7.6, 12.0, 14.1, 16.0, and 18.5 MeV. A sensitivity study establishes the importance of A(y) (theta) in determining the 3P0,1,2 phase shifts in n-p scattering. The data are compared to the predictions of two phase-shift studies (one of which incorporates CIB effects), and the Paris and Bonn NN potentials.

Experimental methods to measure the vector analyzing powers over a broad range of kinematic configurations in the n-d breakup reaction have been developed at TUNL. These techniques employ the polarized beam facilities at TUNL and use the 2H(d, n)3He reaction as a source of low-energy polarized neutrons. Our methods permit measurements to a high statistical accuracy over a large fraction of three-nucleon phase space. The techniques are described and experimental spectra along with kinematic calculations are presented.

The atomic simulation code EVOLVE is used to calculate the fluence-dependent sputtering yield of a 200 Å thick Cu film bombarded by 180 keV Ar atoms incident at 50° with respect to the target normal. The EVOLVE code has also simultaneously calculated the fluence-dependent compositional changes in the target which had bulk Al backing behind the Cu film. Comparison of the calculational results with the experimentally available Cu total sputtering yield and Al differential sputtering yield measurements shows good agreement.

The sputtering yields from thin Cu films of various thicknesses on aluminum backings, with 180 keV Ar+ ions, have been determined. The evolution of the ion-induced optical emission from the substrate, used to determine the ion dose necessary to sputter the film, was compared with predictions from the EVOLVE code for similar film thicknesses and sputtering conditions. The data and the predictions coincide for a 200 Å film. For thicker films, they are similar but don't overlap. The sputtering process is well described by the EVOLVE code. For two of the films the experimental yield values are slightly lower than the predictions from the code, but the results, both experimental and from the simulation, are consistent with the idea that for very thin films the yield is smaller than that of infinitely thick targets and decreases as the film thickness decreases.

The vector analyzing power for the $n+d\ensuremath{\rightarrow}n+n+p$ breakup reaction was measured at 12 MeV. Data for $n\ensuremath{-}p$ final-state interaction and $n\ensuremath{-}p$ quasifree scattering, along with elastic-scattering data, are compared to rigorous three-nucleon calculations using the Paris and Bonn $N\ensuremath{-}N$ potentials. Calculations agree with the quasifree data and with the elastic and $n\ensuremath{-}p$ final-state-interaction data except around ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}=120\ifmmode^\circ\else\textdegree\fi{}$.

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.

The cross section and the analyzing powers Ay, Axx, Axz and Ayy for the reaction H(d, 2p)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.

Sputtering yields and angular distributions have been measured as functions of sample preparation techniques and incident ion-beam orientation with respect to the crystal axes for 100 keV Cu-ion beams on Cu crystals and polycrystalline samples. The angular distributions have structure requiring an nth order cosine with two Gaussians superimposed to fit the data; strong peaking is observed near the backscatter direction. The yield is dependent on the beam to crystal and beam to polycrystalline-rod axis orientation, on the grain size of the polycrystals and on sample-preparation techniques. Yield measurements vary by as much as a factor of 4. Lattice-damage differences, measured with alpha particle channeling, are much smaller and seem to be saturated by fluences of the order of 1 × 1016/cm2.