We recently installed a simple endstation at the Naval Academy Tandem Accelerator Laboratory to support student projects using external-beam PIXE and PIGE. It consists of a short, graphite-lined beamline extension with a thin window, an interlocked box that surrounds the target, detectors for x-and gamma rays, provision for flooding the target with helium gas, easily changed x-ray absorbers, and a compact video camera for monitoring the position of the beam spot. We used this system to measure the elemental composition of colonial-era architectural materials, principally bricks and mortar, from James Madison's Montpelier, the reconstructed Virginia estate of the fourth President of the United States. We describe the design and construction of the system, relate some of our experiences using it, and present some preliminary data from our investigations.

HMB DeBraak was a 16-gun British brig-sloop that sank in a squall on May 25, 1798 off Cape Henlopen, Delaware. Silt covered the wooden hull shortly after it sank, preserving it until DeBraak was raised in 1986. The items recovered from the ship include metal bolts that held the hull together. We used PIXE to measure the compositions of 45 of the bolts and found that they are nearly pure copper (98.3% on average), with most also containing small amounts of iron (0.87%), nickel (0.039%), arsenic (0.43%), silver (0.089%), lead (0.18%), and bismuth (0.12%). A few contain a little indium, tin, or antimony, but none contain zinc above the quantization level. The compositions are similar to those reported for 18th-century English copper, but different from several copper alloys also used to make hull bolts. We conclude that, when DeBraak was last fitted out in 1795 - 1797, the Royal Navy was still using bolts similar to William Forbes's mechanically hardened pure copper bolts. Forbes's process represents the successful innovation and application of new technology in Royal Navy ships during the wars of the late 18th century.

The Naval Academy Tandem Accelerator Laboratory is dedicated to providing educational experiences for undergraduates. Students gain experience in accelerator operations, detector and data acquisition systems, nuclear structure and reaction mechanisms, and materials analysis techniques. Suggestions for managing the laboratory sessions are given. Examples introducing Coulomb excitation, resonance reactions, and depth profiling are described.

A simple external-beam ion milliprobe system was designed and constructed as part of an undergraduate honors research project. The system includes an adjustable object slit, a compact electrostatic quadrupole triplet lens, a lens positioner, and a shielded tip with a thin Kapton window through which the beam exits the accelerator vacuum and enters a sample enclosure with interlocked doors. Auxiliary equipment includes a four-segment lens-entrance collimator with a beam-current monitor that facilitates steering the beam and an interlock system that intercepts the beam when any of the doors to the sample enclosure are opened. Details of the design and construction of the system will be presented and its performance will be described.

In this paper, we describe a system we have designed and assembled which is intended to protect users of a small tandem accelerator from serious exposure to ionizing radiation. This goal is complicated by the fact that our accelerator, target area, control console and data acquisition area are all contained in a single room. In our system, commercially available gamma and neutron monitors, illuminated warning signs and magnetic door switches are combined with a custom-built interlock chassis and a simple modification to the accelerator's chain motor power contactor. A key switch prevents unauthorized persons from energizing the chain. Warning signs above the entrances to the accelerator lab indicate one of three operating conditions: accelerator off, chain power on, and radiation warning (radiation levels above 0.1 mR/h). If radiation levels in the lab exceed 2 mR/h, power to the c motor is cut off. Chain power is also cut off when one of the lab doors is opened, unless the operator deliberately and temporarily overrides the system to permit entrance or exit.

The U.S. Naval Academy is developing an accelerator laboratory to support undergraduate research and teaching. The laboratory includes a 1.7-MV tandem electrostatic accelerator, an rf charge-exchange negative ion source, and a beamline containing a scattering chamber and an external-beam ion milliprobe. The milliprobe was built as part of one senior honors project, and is being used in another to study archeological samples by in-air PIXE. The laboratory has been used in a senior-level nuclear physics course to demonstrate resonant scattering of protons from 12C and in a junior-level atomic physics course to demonstrate Moseley's law and the principles of PIXE analysis. This paper describes the laboratory and its applications during the first year of operation.

Ion implantation and other ion-beam processing techniques sometimes roughen the surfaces to which they are applied. If undetected, such roughness can lead to erroneous interpretation of data gathered by RBS, AES, and other surface analysis techniques. Many surface profilometers and scanning electron microscopes lack sufficient resolution to detect fine-scale roughness that can complicate the data interpretation. We have constructed a simple optical instrument to measure the root-mean-square (rms) roughness, below ~ 100 nm, of ion-implanted surfaces. This instrument measures the total integrated scatter (TIS) of almost-normally incident laser light, which (under certain conditions) is simply related to the rms surface roughness. This paper describes the construction and calibration of the TIS instrument, and presents preliminary results on the roughness of Cr surfaces deposited under various vacuum conditions and implanted during deposition with energetic Cr ions.

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.

The total reaction cross section ${\ensuremath{\sigma}}_{R}$ for $^{3}$He${+\mathrm{}}^{3}$He has been obtained at laboratory bombarding energies of 17.9, 21.7, and 24.0 MeV by measuring the individual cross sections for production of protons, deuterons, tritons, $^{3}\mathrm{He}$, and \ensuremath{\alpha} particles. The accuracy of the results is greatly improved by taking advantage of a novel method which depends on the symmetry about 90\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system of the reaction cross sections for identical particles in the incoming channel. Use of this method reduces the range of energy and angle which must be measured for the continuous spectra of particles emitted in these multibody final states. In order of increasing energy, the values of ${\ensuremath{\sigma}}_{R}$ obtained in this experiment are 156.7\ifmmode\pm\else\textpm\fi{}3.8, 250\ifmmode\pm\else\textpm\fi{}14, and 296\ifmmode\pm\else\textpm\fi{}12 mb. Individual cross sections contributing to ${\ensuremath{\sigma}}_{R}$ were also extracted. Implications of the measurements for resonating group calculations of $^{3}$He${+\mathrm{}}^{3}$He scattering are examined.

This work evaluates the importance of sputtering and diffusion to the measured concentration profiles of Ta implanted into Fe. The samples consisted of thin Fe films deposited on sapphire or glass substrates and implanted with ISO keV Ta ions to fluences of (1−18) × 1016ionscm2. Rutherford backscattering analysis provided measurements of the retained dose, the sputtering rate of Fe and Ta, and the evolution of the Ta depth distribution, all as a function of ion dose. These measurements indicated that preferential removal by sputtering combined with atomic migration led to a 50% increase in the saturation retained dose of Ta, when compared to the value predicted by simple theory without these two effects.

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 ground-state magnetic dipole and electric quadrupole moments of the ..beta.. emitter /sup 9/Li (J/sup ..pi../ = (3/2)/sup -/, T/sub 1/2/ = 0.176 s) have been measured for the first time. Polarized /sup 9/Li nuclei were produced in the /sup 7/Li(t,p) reaction, using 5--6 MeV polarized tritons. The recoiling /sup 9/Li nuclei were stopped either in Au foils or in LiNbO/sub 3/ single crystals, and their polarization was detected by measuring the ..beta..-decay asymmetry. Nuclear magnetic resonance techniques were used to depolarize the nuclei, and the resonant frequencies were deduced from changes in the asymmetry. The /sup 9/Li dipole moment was deduced from the measured Larmor frequency in Au; the result, including corrections for diamagnetic shielding and the Knight shift, is Vertical Bar..mu..Vertical Bar = 3.4391(6) ..mu../sub N/. The ratio of the /sup 9/Li quadrupole moment to that of /sup 7/Li was derived from their respective quadrupole couplings in LiNbO/sub 3/; the value is Vertical BarQ( /sup 9/Li)/Q( /sup 7/Li)Vertical Bar = 0. 88 +- 0.18. Both results are in agreement with shell model predictions.

The ground-state magnetic dipole and electric quadrupole moments of the $\ensuremath{\beta}$ emitter $^{9}\mathrm{Li}$ (${J}^{\ensuremath{\pi}}={\frac{3}{2}}^{\ensuremath{-}}$, ${T}_{\frac{1}{2}}=0.176$ s) have been measured for the first time. Polarized $^{9}\mathrm{Li}$ nuclei were produced in the $^{7}\mathrm{Li}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{t}}, \mathrm{p})$ reaction, using 5-6 MeV polarized tritons. The recoiling $^{9}\mathrm{Li}$ nuclei were stopped either in Au foils or in LiNb${\mathrm{O}}_{3}$ single crystals, and their polarization was detected by measuring the $\ensuremath{\beta}$-decay asymmetry. Nuclear magnetic resonance techniques were used to depolarize the nuclei, and the resonant frequencies were deduced from changes in the asymmetry. The $^{9}\mathrm{Li}$ dipole moment was deduced from the measured Larmor frequency in Au; the result, including corrections for diamagnetic shielding and the Knight shift, is $|\ensuremath{\mu}|=3.4391(6)$ ${\mathrm{\ensuremath{\mu}}}_{\mathrm{N}}$. The ratio of the $^{9}\mathrm{Li}$ quadrupole moment to that of $^{7}\mathrm{Li}$ was derived from their respective quadrupole couplings in LiNb${\mathrm{O}}_{3}$; the value is $|\frac{Q(^{9}\mathrm{Li})}{Q(^{7}\mathrm{Li})}|=0.88\ifmmode\pm\else\textpm\fi{}0.18$. Both results are in agreement with shell model predictions.RADIOACTIVITY Polarized $^{9}\mathrm{Li}$ from $^{7}\mathrm{Li}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{t}}, \mathrm{p})$; measured $\ensuremath{\beta}$ asymmetry, polarization transfer, NMR; deduced $^{9}\mathrm{Li}$ magnetic moment $|\ensuremath{\mu}|$, ratio $^{9}\mathrm{Li}$ to $^{7}\mathrm{Li}$ quadrupole moments $|\frac{Q(^{9}\mathrm{Li})}{Q(^{7}\mathrm{Li})}|$. Comparison with shell-model values.

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 tenso...

The cross section and the analyzing powers Ay, Axx and Ayy for the reaction 4He(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 Ay 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.

Cross sections and analysing powers have been measured for the elastic and inelastic scattering of tritons from 32S, along with the 32S(t, α)31P reaction data, using the 17 MeV polarised triton beam available at the Los Alamos National Laboratory. An optical model analysis of the elastic scattering data has yielded a triton spin-orbit potential with an unconventional geometry. The inelastic analysing powers have shown a requirement for including the deformation of the spin-orbit potential in the coupling potential form factor. The (t, α) reaction data have been analysed using the zero-range DWBA. Certain features of this reaction data which could not be described by the DWBA are well predicted when the analysis is extended to include explicitly the inelastic couplings and two-step processes through a CCBA calculation.