The first spin-transfer experiment performed for the $\ensuremath{\pi}d\ensuremath{\rightarrow}\ensuremath{\rightarrow}p\ensuremath{\rightarrow}p$ reaction is described. Three spin-transfer parameters for this $\ensuremath{\pi}$-absorption process were determined, ${K}_{\mathrm{LS}}^{a}$, ${K}_{\mathrm{SS}}^{a}$, and ${K}_{\mathrm{NN}}^{a}$, which correspond to the \ensuremath{\pi}-production parameters, ${K}_{\mathrm{SL}}^{p}$, ${K}_{\mathrm{SS}}^{p}$, and ${K}_{\mathrm{NN}}^{p}$, of the time-reversed $p\ensuremath{\rightarrow}p\ensuremath{\rightarrow}d\ensuremath{\rightarrow}\ensuremath{\pi}$ process. Each observable was measured at a single angle for a number of energies spanning the $\ensuremath{\Delta}$ resonance of this system. The results are compared with the predictions of published partial wave amplitude fits which are primarily based on existing data for the time-reversed $\mathrm{pp}\ensuremath{\rightarrow}d\ensuremath{\pi}$ reaction, and also with the predictions of two current theories. The failure of these theories to describe the fundamental features of the data clearly demonstrates the need for further theoretical work in this area.

As part of an experimental study of the pi NN system, the pion-deuteron breakup reaction pi(+)(d) over right arrow-->pn pi(+) was investigated at intermediate energies. Distributions of the vector analyzing power iT(11) versus outgoing proton momentum P-p are presented for 36 pi p angle pairs in the range of scattering angles 20)degrees less than or equal to theta(p) less than or equal to 51 degrees, 62 degrees less than or equal to theta(pi)less than or equal to 124 degrees at 228 and 134 MeV. These include 7 previously unmeasured angle pairs at 228 MeV and 20 new pairs at 134 MeV. In all regions of overlap with previous measurements, there is excellent agreement. There is generally excellent agreement with relativistic Faddeev predictions, except in the np final-state interaction region at 228 MeV. This is in contrast to the cross-section measurements, which are not well described by the theory.

As part of an experimental study of the piNN system, the pion absorption reaction, pi+d over arrow pointing right --> pp, is investigated at low energy. Angular distributions of the vector analyzing power, iT11, are presented for six complementary angle pair coincidences at 65 MeV and five pairs at 25 MeV. There is good agreement with previous measurements, and a significant improvement in uncertainties has been achieved. Results are compared with theoretical predictions based on three different approaches. The best agreement is with a relativistic Faddeev calculation by the Lyon group. Calculations based on the partial wave solutions of Arndt et al. are compared with the data at both energies.

The polarized target asymmetry ${\mathit{A}}_{\mathit{N}}$ for ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}\ensuremath{\rightarrow}\ensuremath{\gamma}n has been measured by coincident detection of the \ensuremath{\gamma} and the neutron at several angles across the \ensuremath{\Delta} resonace energy region. A high-resolution NaI \ensuremath{\gamma} spectrometer together with good time-of-flight information for the neutron resulted in excellent separation of this radiative capture reaction from the much higher cross-section charge exchange reaction ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{0}$n. Statistical uncertainties are \ensuremath{\Delta}${\mathit{A}}_{\mathit{N}}$=0.02-0.04, representing a significant improvement over previous results. The new data are discussed in the context of recent theoretical models.

The polarized target asymmetry A(N) for pi(-)(p) over right arrow-->gamma n has been measured by coincident detection of the gamma and the neutron at several angles across the Delta resonance energy region. A high-resolution NaI gamma spectrometer together with good time-of-flight information for the neutron resulted in excellent separation of this radiative capture reaction from the much higher cross-section charge exchange reaction pi(-)(p) over right arrow-->pi(0)n. Statistical uncertainties are Delta A(N) = 0.02 - 0.04, representing a significant improvement over previous results. The new data are discussed in the context of recent theoretical models.

Measurements of the vector analyzing power iT11 in pid elastic scattering at 49 MeV have been performed using a dynamically polarized target and a magnetic spectrometer. Data at seven pi+ laboratory scattering angles between 50-degrees and 130-degrees were taken together with a complementary measurement at 60-degrees for pi-d elastic scattering. In general, we find agreement with models that include the piN P11 amplitude and disagreement with models that exclude or suppress it.

Measurements of the analyzing power for the C-13 -->(pi +/-, pi +/-) reaction at T(pi) = 100 MeV have been made at TRIUMF using a polarized target consisting of 99% C-13 enriched butanol. Data were obtained for the ground and 3.68 MeV excited states at angles from 110-degrees to 150-degrees in 10-degrees steps. The data are consistent with zero asymmetry throughout most of this angular range. Uncertainties are typically +/- 15%, which is sufficient to discriminate among some, but not all, of the currently available theoretical predictions.

A broad goal of many few body physics experiments at intermediate energies is to identify shortcomings of our "conventional" descriptions based on nucleons, nucleon resonances and mesons. Fkom these shortcomings it is often hoped to glean some evidence for the contributions of quarks and gluons. In addition one establishes specific oals for particular reaction channels, which upon realization furthers the empiric3 understanding of that channel, and in some small way also contributes to the above broad goal. Studies of the set of reactions involving the n-NN system must take into account the fact that this system is composed of a coupled set of reactions and that what is learned from one channel improves our understanding of the other coupled channels.

Angular distributions of the analyzing powers for +p and -pelastic scattering have been measured in a single-scattering experiment employing a polarized proton target. Measurements were obtained for pion energies of 98, 139, 166, 215, and 263 MeV. The addition of these data to the existing p database significantly reduces the uncertainties in all S and P phase shifts for p reactions over the delta resonance. © 1989 The American Physical Society.

Angular distributions of the tensor analyzing powers T20 and τ21 have been measured for πd↘ elastic scattering, in a single scattering experiment employing a tensor polarized deuteron target. Measurements of T20 were obtained for pion bombarding energies of 134, 151, 180, 220, and 256 MeV. Measurements of τ21 were obtained for pion bombarding energies of 134, 180, and 220 MeV. The results are compared with three‐body calculations where effects relating to pion absorption are seen to play an important role.

The first measurements of the tensor analyzing power ${T}_{21}$ in the \ensuremath{\pi}d elastic scattering reaction have been made using a tensor polarized deuteron target. Eleven angles were studied at a pion bombarding energy of 180 MeV. The results are shown to be in agreement with Faddeev calculations.

The tensor alignment pzz of a polarized deuteron target was measured directly for the first time. The measurement utilizes the tensor analyzing power T20 of the πd to 2p reaction at 90° (c.m.), which is well determined from partial wave analysis and consistent theoretical predictions. The resulting value of pzz agrees well with that calculated from the vector polarization pz obtained from NMR techniques.

Current interest in spin observables in pi−d elastic scattering has shifted to excitation of dibaryon resonances. A study of tensor analyzing power from elastic pi−d scattering reveals negative evidence for these proposed dibaryons.

Spin-spin correlation parameters ALL, ANN, ASS, ASL and spin asymmetries ANO and AON have been measured for the reaction pp → pnπ+ with incident beam energies of 510, 465 and 420 MeV. Clean separation of free proton events from the bound proton background has been achieved. ALL, ASS and ANN, were all found to be large and negative indicating domination by the 1D2 partial wave. The spin asymmetries were large. Results are compared to the predictions of Dubach, Kloet and Silbar.

New pp measurements of Delta sigma L and Delta sigma T between 200 and 520 MeV disagree with earlier Argonne data, and resolve discrepancies with inelastic data, phase-shift analysis and forward dispersion relations.