At the Los Alamos Neutron Science Center (LANSCE), spallation neutrons are produced by an 800-MeV proton beam interacting with tungsten targets. Gun-barrel-type penetrations through the heavy concrete and steel shielding that surround the targets collimate neutrons to form neutron beams used for scattering experiments. Two liquid hydrogen moderators of one-liter volume each are positioned adjacent to the neutron-production targets. Some of the neutrons that pass through a moderator interact with or scatter from protons in the hydrogen. The neutron-proton interaction reduces the energy or moderates neutrons to lower energies. Lower energy "moderated" neutrons are the most useful for some neutron scattering experiments. We provide a description of the LANSCE hydrogen-moderator system and its cryogenic performance with proton beams of up to 125 micro-amp average current.

Measurements are presented for several mixtures of the spin observables C-SS, C-SL = C-LS, C-LL, and C-NN for neutron-proton elastic scattering. These data were obtained with a free polarized neutron beam, a polarized proton target, and a large magnetic spectrometer for the outgoing proton. The neutron beam kinetic energies were 484, 567, 634, 720, and 788 MeV Combining these results with earlier measurements allows the determination of the pure spin observables C-SS, C-LS, and C-LL at 384, 634, and 788 MeV for c.m. angles 25 degrees less than or equal to theta(c.m.)less than or equal to 180 degrees and at 720 MeV for 35 degrees less than or equal to theta(c.m.)less than or equal to 80 degrees. These data make a significant contribution to the knowledge of the isospin-0 nucleon-nucleon scattering amplitudes.

The spin correlation parameter ${\mathit{A}}_{00\mathit{N}\mathit{N}}$ for 497.5 MeV proton + proton elastic scattering was determined over the center-of-momentum scattering angle region 23.1\ifmmode^\circ\else\textdegree\fi{}--64.9 \ifmmode^\circ\else\textdegree\fi{}. The new ${\mathit{A}}_{00\mathit{N}\mathit{N}}$ extend to more forward angles than existing ${\mathit{A}}_{00\mathit{N}\mathit{N}}$ and have significantly smaller statistical errors (\ifmmode\pm\else\textpm\fi{}0.01--0.04). The ${\mathit{A}}_{00\mathit{N}\mathit{N}}$ are qualitatively described by recent phase shift analyses, but a quantitative shape and normalization discrepancy remains in the forward angle region. These new data provide important constraints for nucleon-nucleon spin-dependent amplitudes at forward angles which are used in theoretical models of nucleon-nucleus scattering.

The spin correlation parameter [ital A][sub 00[ital N][ital N]] for 497.5 MeV proton + proton elastic scattering was determined over the center-of-momentum scattering angle region 23.1[degree]--64.9 [degree]. The new [ital A][sub 00[ital N][ital N]] extend to more forward angles than existing [ital A][sub 00[ital N][ital N]] and have significantly smaller statistical errors ([plus minus]0.01--0.04). The [ital A][sub 00[ital N][ital N]] are qualitatively described by recent phase shift analyses, but a quantitative shape and normalization discrepancy remains in the forward angle region. These new data provide important constraints for nucleon-nucleon spin-dependent amplitudes at forward angles which are used in theoretical models of nucleon-nucleus scattering.

A measurement of DELTAsigma(L)(np), the difference between neutron-proton total cross sections for pure longitudinal spin states, is described. Data were taken at LAMPF for five neutron beam kinetic energies: 484, 568, 634, 720, and 788 MeV. The statistical errors are in the range 0.64-1.35 mb. Various sources of systematic effects were investigated and are described. Overall systematic errors are estimated to be on the order of 0.5 mb and include an estimate for the uncertainty in the neutron beam polarization. The DELTAsigma(L) results are consistent with previous results from PSI and Saclay. These data, when combined with other results and fitted to a Breit-Wigner curve, are consistent with an elastic I=0 resonance with mass 2214 +/- 15 (stat) +/- 6 (syst) MeV and width 75 +/- 21 +/- 12 MeV. Because of a lack of DELTAsigma(T)(np) data between 500 and 800 MeV, it is not possible to differentiate between a singlet or coupled-triplet partial wave being responsible.

The spin correlation parameter A00NN for 497.5 MeV proton+proton elastic scattering was determined over the center-of-momentum scattering angle region 23.1-degrees - 64.9-degrees. The new A00NN extend to more forward angles than existing A00NN and have significantly smaller statistical errors (+/-0.01 - 0.04). The A00NN are qualitatively described by recent phase shift analyses, but a quantitative shape and normalization discrepancy remains in the forward angle region. These new data provide important constraints for nucleon-nucleon spin-dependent amplitudes at forward angles which are used in theoretical models of nucleon-nucleus scattering.

Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene.

The spin-correlation observable A« for p-p elastic scattering has been measured at energies 589, 640, 692, 743, and 793 MeV, over a c.m. angular range between 20' and 100. The spin observable As& was also measured in this angular range at energies 640 and 793 MeV. At 488 MeV both the spin observables were measured, but only near the c.m. angle of 90'. The data are compared with the predictions of several phase-shift analyses and previous measurements. The energy dependence of ALL for the c.m. angle of 90' is also presented and shows no anomalous behavior. These data provide better angular coverage over five of the energies, with comparable or better statistical precision, than previous measurements of ALz.

The spin-correlation observable A(LL) for p-p elastic scattering has been measured at energies 589, 640, 692, 743, and 793 MeV, over a c.m. angular range between 20-degrees and 100-degrees. The spin observable A(SL) was also measured in this angular range at energies 640 and 793 MeV. At 488 MeV both the spin observables were measured, but only near the c.m. angle of 90-degrees. The data are compared with the predictions of several phase-shift analyses and previous measurements. The energy dependence of A(LL) for the c.m. angle of 90-degrees is also presented and shows no anomalous behavior. These data provide better angular coverage over five of the energies, with comparable or better statistical precision, than previous measurements of A(LL).

Samples of [sup 7]LiH material were irradiated with an electron beam of 30 MeV; doses ranged from 0.5 to 3.6[star]10[sup 17]e[sup [minus]]/cm[sup 2]. During irradiation the material was cooled by cold helium gas with a gas temperature range of 180--200 K. The samples were dynamically polarized in either a dilution or a [sup 3]He evaporation refrigerator in a 2.5 T. magnetic field. Polarization results and relaxation measurements are reported.

A measurement of DELTA-sigma-L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. Data were taken for five energies between 500 and 800 MeV, with statistical errors of almost-equal-to 1.5 mb and an estimated normalization error of 6%. The data, combined with other results, show some evidence for an elastic I = 0 spin-singlet resonance with mass approximately 2213 MeV and width approximately 74 MeV, or a coupled-triplet resonance with similar mass and width.

A 24-element plastic scintillation counter hodoscope for np elastic and total cross section measurements at LAMPF is described. Details of construction, electronics, calibration with cosmic ray muons, and a determination of absolute detection efficiency at 289 and 435 MeV are presented.

Results of the first pion single-charge-exchange experiment on a polarized nuclear target are reported. Analyzing powers A(y) for the (pi+, pi-0) reaction at T-pi+ = 163 MeV on a polarized C-13 target were measured over an angular range between 20-degrees and 60-degrees in the laboratory system. Calculations in the distorted-wave impulse approximation do not reproduce these new data.

Ethylene glycol, 1-butanol, and toluene highly enriched in 13C have been used at LAMPF to produce dynamically polarized 13C targets for scattering experiments with protons and pions. Preparation of the materials and characteristic properties of these, targets are described.

Analyzing powers A(y) were measured for pi+ and pi- elastic scattering from polarized C-13 at energies near the P-33 resonance. At T-pi = 132 MeV the values of A(y) are significantly different from zero for pi-. For pi+ at 132 MeV and for both pi- and pi+ at all other energies, the A(y) are mostly consistent with zero. These data differ from the predictions of present pion-nucleus reaction theories, especially at large momentum transfers.