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Polarization transfer measurements in π+ elastic scattering have been performed at two incident pion energies, one below and one at the Δ(3, 3)-resonance. Using a vector polarized deuteron target four polarization transfer observables are determined. The results are compared to predictions from Faddeev calculations.

Polarization transfer observables in π + d elastic scattering have been measured for the first time. Four polarization transfer parameters were determined at pion energies T π =134 MeV and 180 MeV at scattering angles θ π ,C.M. between 100° and 140° using a deuteron target polarized perpendicular to the scattering plane and a deuteron tensor polarimeter. The data are compared to different predictions from the SAID phase shift analysis and Faddeev calculations.

Polarization transfer measurements in π+ elastic scattering have been performed at two incident pion energies, one below and one at the Δ(3, 3)-resonance. Using a vector polarized deuteron target four polarization transfer observables are determined. The results are compared to predictions from Faddeev calculations.

The vector analyzing power [ital iT][sub 11] and the tensor analyzing power [tau][sub 22]=[ital T][sub 22]+[ital T][sub 20]/ [radical]6 have been measured for [pi][sup +][r arrow][sup 6]L[rvec i] elastic and inelastic scattering (to the 3[sup +]0, 2.19 MeV state) at incident pion energies of 120, 150, 180, and 194 MeV. These data and earlier ones from our group are compared with new coupled channels calculations. Within the coupled channels model, the influence of different nuclear wave functions, the strength of the coupling of the ground and first excited states, and the effects of the phenomenological second-order potential were investigated. It was found that the calculated vector analyzing power [ital iT][sub 11] depends strongly on the transverse form factor whichever nuclear wave function is chosen. In the angular region where the [ital iT][sub 11] data were taken the coupling of the ground to the first excited state has a minor effect on the theoretical predictions. Reasonable agreement with the data can be obtained for a large energy and angular region with the first-order potential only.

The inclusive vector analyzing power [ital iT][sub 11] of [pi][sup +][r arrow][sup 7]Li elastic scattering and inelastic scattering to the 0.47 MeV excited state was measured at several angles for [ital T][sub [pi]]=134, 164, and 194 MeV. The polarization effects were found to be small but nonzero, the trend of the data is well described by a coupled channels calculation. The results of the calculation are more sensitive to variations of the nuclear structure input than to variations of the reaction mechanism.

New experimental results are presented on the interaction of pions with nuclei of mass A = 2,3,4 and 6. The data are compared with theoretical calculations. Some open theoretical problems are discussed and an outlook on future experiments is given.

The analyzing power ${\mathit{A}}_{\mathit{y}}$ was measured for ${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{-}}}^{15}$N\ensuremath{\rightarrow} elastic scattering at ${\mathit{T}}_{\mathrm{\ensuremath{\pi}}}$=164 MeV between 40\ifmmode^\circ\else\textdegree\fi{} and 100\ifmmode^\circ\else\textdegree\fi{} using a polarized $^{15}\mathrm{NH}_{3}$ target. Within the statistical accuracy of the data ${\mathit{A}}_{\mathit{y}}$(\ensuremath{\theta}) was found to be zero over the full angular range. These data together with differential cross sections from the literature are compared with theoretical predictions based on a momentum-space coupled-channel formalism. While the cross section is very well reproduced there are large discrepancies in the analyzing power for which large spin effects are predicted close to the cross-section minima. Possible deficiencies in the theoretical model are discussed.

Vector and tensor analyzing powers were measured for π+‐6Li↘ and π+‐7Li↘scattering in the angular range between 50° and 110° at several pion energies in the region of the Δ(3,3) resonance. The data are compared to predictions from a coupled channel model. Within this model the sensitivity to variations of the nuclear structure input and the reaction mechanism are investigated.

The first measurements of pion scattering and pion single charge exchange on polarized complex nuclei, obtained at PSI, LAMPF and TRIUMF, are reported. Large spin effects were obtained in pion elastic and inelastic scattering (3+, 2.19 MeV state) in \({}^{6}\overrightarrow{\text{Li}}\). Contrary to these results only small analyzing powers were obtained for pion elastic scattering from \({}^{13}\overrightarrow{\text{C}}\) and \({}^{15}\overrightarrow{\text{N}}\). However, in pion single charge exchange on \({}^{13}\overrightarrow{\text{C}}\) large spin effects were seen. The data are compared with theoretical predictions applying the momentum space optical model and the ∆-hole model, as well as DWIA. In general, the agreement is quite poor, and there are indications that the scattering models as well as the nuclear structure input must be refined.

The composite spin observable tau/sub 22/equivalent(T/sub 22/+T/sub 20// ..sqrt..6 ) has been measured at five incident pion energies between 134 and 294 MeV, in an angular range between 90/sup 0/ and 170/sup 0/, using a tensor-polarized deuterium target. New, accurate data for the vector analyzing power iT/sub 11/ were obtained at the same time. In combination with the results reported in part I of this series, our measurements allow us to determine the three analyzing powers T/sub 20/, T/sub 21/, and T/sub 22/, separately, and compare them with existing theoretical calculations, all of which fail, in one way or another, to reproduce the entire data set.

We have measured energies and angular distributions of three protons detected in coincidence following absorption of 228 MeV ${\ensuremath{\pi}}^{+}$ in carbon. The counters used were arranged in a geometry that should have enabled observation of the two-step process of proton knockout followed by quasi-deuteron absorption of the recoil pion. The absence of high energy protons emitted in the backward direction provides strong evidence that such a two-step process does not contribute appreciably to the total absorption cross section, and suggests that in fact the pion may scatter several times before finally being absorbed on a quasi-deuteron.

Three-fold differential cross sections \ensuremath{\sigma}(${\mathrm{theta}}_{\ensuremath{\pi}}$,${\mathrm{theta}}_{\mathrm{p}}$,${P}_{\mathrm{p}}$) have been measured in a kinematically complete experiment over a large region of phase space at 228 and 294 MeV incident pion energy. The data are compared with predictions from a relativistic Faddeev calculation. Excellent agreement is found over most of the phase space. From this good agreement between theory and experiment there appears to be no need for the inclusion of nonconventional dynamics, such as the excitation of dibaryon resonances.

The 12 C (π,π′γ) 12 C ∗ (2 + , T=0,4.44 MeV ) angular correlation function was measured at Tπ=162MeV. Da taken in the reaction plane for a range of γ-angles at each of two pion angles support recent theoritical predictions using the isobar-hole formalism.

The vector analysing power, iT11, and differential cross section for the π + d →π + pn reaction at Tπ = 228 MeV were measured in a kinematically complete experiment, using a polarized deuteron target. Results are presented for a pion angle of 85° with six proton angles between 27° and 61°. A comparison is made with theoretical calculations.

Inelastic pion scattering from $^{16}\mathrm{O}$ has been studied by measuring the spectrum of pions down to 40 MeV at five angles between 30\ifmmode^\circ\else\textdegree\fi{} and 134\ifmmode^\circ\else\textdegree\fi{} for three incident pion energies: 114, 163, and 240 MeV. The spectra are dominated by a broad peak due to quasielastic scattering from a single nucleon in the nucleus. The systematics of the spectra are discussed with emphasis on the pion-nucleus interaction dynamics including the effect of absorption. The partial ${\ensuremath{\pi}}^{+}$-$^{16}\mathrm{O}$ cross sections for all nonradiative channels are estimated.NUCLEAR REACTIONS $^{16}\mathrm{O}(\ensuremath{\pi}, {\ensuremath{\pi}}^{\ensuremath{'}})$ $E=114, 163, 240$ MeV. $\ensuremath{\theta}=30\ensuremath{-}134\ifmmode^\circ\else\textdegree\fi{}$, full inelastic spectrum measured; $\ensuremath{\sigma}(\ensuremath{\theta})$. Discussion of nuclear medium effects on quasifree processes, $\ensuremath{\Delta}$ propagation.

The dynamics of the ΔN-system in the lightest nuclei, its effects, and properties are reviewed and discussed.

The vector analyzing power iT/sub 11/ has been measured for the ..pi..d elastic scattering reaction at 12 incident pion energies between 117 and 325 MeV, using a vector polarized deuteron target. The results cover an average of 14 angles per incident pion energy. A detailed comparison with existing Faddeev calculations is made. The effect of including dibaryon resonances with one of these predictions is investigated.

We have measured the reactions 12 C (π ± , π ± d ) 10 B and 12 C (π ± , π ± t ) 9 B at an incident pion energy of 180 MeV, with two spectrometers in coincidence. The ratio σ(π+, π+d)/σ(π−, π−d) agrees with the iso-spin prediction of unity. There is evidence for quasi-elastic πd acattering. We obtain the surpising result that the ratio σ(π, πd)/σ(π, πp), for excitation energies less than 10 MeV, is equal to the ratio (dσ/dω) (πd)/(dσ/dω) (πp) for elastic (πd) and (πp) scattering at all the points we have measured. The ratio σ(π−, π−t)/gs(π+, π+t) is approximately one and there is no evidence for quasi-elastic πt scattering.

The vector analyzing power iT/sub 11/ has been measured for the ..pi..d..-->..2p reaction at seven incident pion energies between 112 and 325 MeV, using a vector polarized deuteron target. The results cover an average of 12 angles per incident pion energy. A comparison with existing theoretical calculations is made. The value of these data with respect to ongoing phase shift analyses of the pp..--> pi..d reaction is discussed.

There has been remarkable experimental and theoretical progress in the field ofπd interactions in the last few years. Within the uncertainties of the theory the experimental data in theπd breakup and theπd elastic scattering reaction can be fairly well reproduced. Theoretical problems remain in the absorption channel, but there is a hope that with a few additional measurements of tensor polarization and spin transfer observables in this reaction a partial wave amplitude analysis may localize the theoretical difficulties. In addition it is very important to provide data on the deuteron tensor polarizations and the spin transfer parameters for theπd elastic scattering reaction in order to obtain a reliable set of phase shifts, which may reveal resonance structures in this reaction channel.

The composite spin observable ${\ensuremath{\tau}}_{22}$\ensuremath{\equiv}(${T}_{22}$+${T}_{20}$/ \ensuremath{\surd}6 ) has been measured at five incident pion energies between 134 and 294 MeV, in an angular range between 90\ifmmode^\circ\else\textdegree\fi{} and 170\ifmmode^\circ\else\textdegree\fi{}, using a tensor-polarized deuterium target. New, accurate data for the vector analyzing power ${\mathrm{iT}}_{11}$ were obtained at the same time. In combination with the results reported in part I of this series, our measurements allow us to determine the three analyzing powers ${T}_{20}$, ${T}_{21}$, and ${T}_{22}$, separately, and compare them with existing theoretical calculations, all of which fail, in one way or another, to reproduce the entire data set.

The elastic and inelastic (3 − , 2.6 MeV) scattering of pions by 208 Pb has been measured at 80 MeV ( π + only) and 116 MeV (π + and π − ). An optical potential model including quadratic density terms reproduces well the transition from diffractive scattering at the higher energies to the non-diffractive behavior observed at 50 MeV. Good agreement with the inelastic data is obtained with a collective model using the same deformation length βR = 0.85 fm ( β = 0.13) for π + and π − .

The cross section of the pion-induced proton-knockout reaction /sup 12/C ..-->.. /sup 11/B has been measured with positive and negative pions. The ratio of the cross sections is compared with the ratio calculated in the plane-wave impulse approximation and agreement is found for those events that lead to particle-stable final states.

The ..pi..-d elastic differential cross-section and the vector analyzing power have been measured between CTHETA/sub c.m./ = 95/sup 0/ and 165/sup 0/ at incident pion energies between 117 and 151 MeV. Both observables show a smooth behavior as a function of angle and energy.

The vector analyzing power iT/sub 11/ has been measured for the ..pi..d..-->..pp reaction at an incident pion energy of 65 MeV, using a vector polarized deuteron target. The data are compared with predictions from coupled channels, Faddeev, and perturbation theory calculations.

We have performed an experiment in which we have detected three protons incoincidence, following the absorption of positive pions in carbon. Data werecollected with twelve plastic scintillator detectors, covering a fairly largeregion of the available phase space, at three incident pion kinetic energies:/ital T//sub ..pi../=130, 180, and 228 MeV. Comparisons are made with phasespace calculations which simulate quasifree three-nucleon and four-nucleonabsorption mechanisms. The first of these provides an excellent description ofthe bulk of the data. Some of the observed events appear to come fromquasideuteron absorption, followed by a final-state interaction of one of theoutgoing protons. There is no evidence for absorption mechanisms involving morethan three nucleons. Estimates are made for the contributions of thethree-nucleon absorption mechanisms to the total pion absorption cross section.These are relatively small.

The vector analysing power, iT11, has been measured for the π+d → π+pn reaction in a kinematically complete experiment. The dependence of iT11 on the momentum of the proton has been obtained for 35 pion‐proton angle pairs at pion bombarding energies of 180 MeV, 228 MeV and 294 MeV. The data are compared with a relativistic Faddeev calculation.

Inelastic scattering of 163- and 241-MeV positive pions by /sup nat/Ca has been studied with special attention paid to the giant-resonance region. Pronounced giant resonance structures are observed at both incident energies. The analysis indicates a strong excitation of the giant quadrupole resonance at 18.2 MeV (GAMMA approx. 3--3.5 MeV).

Recent experimental results on the πd breakup, the πd elastic scattering, the πd charge exchange and the πd absorption reactions are presented. The data are compared with predictions from different few body theories. Open questions and future experiments are being discussed.

A tensor-polarized deuteron target has been employed for the first measurements of the tensor analyzing power ${T}_{20}$ in $\ensuremath{\pi}d$ elastic scattering. Data at six angles were measured at pion bombarding energies of 133.8 and 150.9 MeV. The results settle a long-standing controversy over conflicting measurements of the tensor polarization ${t}_{20}$, and dispute evidence for dibaryon resonances predicated on one of these ${t}_{20}$ measurements. The data are shown to be in reasonable agreement with recent Faddeev calculations which have reduced contributions from pion absorption.

At an early stage of planning the experimental facilities at SIN it was decided to build a high resolution π-channel and a π-spectrometer for nuclear structure studies. For the π-channel an achromatic system with a large dispersion at the intermediate focus was designed in order to provide a versatile beam line for different kinds of experiments. The lay out is shown in Fig. 1. The π-channel consists of two ion optically almost symmetric sections. The first one (consisting of the quadrupoles Q1 – Q6, the separator S, the compensating magnets Ms, the bending magnet M1 and the beam blocker B) disperses the pion beam (produced at the target P) in the horizontal plane at M. At this point a horizontal focus is also required in order to select the pion momenta by means of a MWPC (C1). The second section (consisting of the bending magnet M2 and the quadrupoles Q7 – Q10 recombines the dispersed beam into an achromatic beam spot on the scattering target (1 cm x 2 cm). The second MWPC (C2) determines the incident angle of the pions on the target.

Angular distributions of cross sections for π + elastic scattering by 16 O have been measured between 14° and 138° at five energies (79, 114, 163, 240 and 343 MeV). They are compared to calculations using a first-order static model and an isobar doorway model. Phase-shift analyses have been done using the theoretical inputs as guidelines. The validity of these models is discussed.

The optical properties of the SIN high resolution pion channel and spectrometer are briefly reviewed. The operation of the whole system, including detectors and data acquisition is then described. Finally the tune-up method and the actual performances are given.