Search

Over 120 million vehicles enter the United States each year. Many are capable of transporting hidden nuclear weapons or nuclear material. Currently deployed X-ray radiography systems are limited because they cannot be used on occupied vehicles and the energy and dose are too low to penetrate many cargos. We present a new technique that overcomes these limitations by obtaining tomographic images using the multiple scattering of cosmic radiation as it transits each vehicle. When coupled with passive radiation detection, muon interrogation could contribute to safe and robust border protection against nuclear devices or material in occupied vehicles and containers.

New high-precision measurements of p( γ , π) and p( γ , γ) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N → Δ transition extracted from this analysis is EMR = -3.0% ± 0.3 (stat + sys) ± 0.2 (model).

We present new break-up and coherent data for $\ensuremath{\eta}$ meson photoproduction on the deuteron, using a deuterium target and tagged bremsstrahlung photons up to 1 GeV. The differential cross sections for the coherent process were measured from threshold to 800 MeV. They are much smaller than those previously reported. The break-up channel provides a direct measurement of the neutron to proton differential cross section ratios. At the ${S}_{11}(1535)$ resonance peak, ${\ensuremath{\sigma}}_{n}/{\ensuremath{\sigma}}_{p}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.68\ifmmode\pm\else\textpm\fi{}0.06$ leading to an isoscalar to isovector amplitude ratio of ${A}_{s}{/A}_{\ensuremath{\upsilon}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.096\ifmmode\pm\else\textpm\fi{}0.02$.

Total cross sections, differential cross sections and asymmetries for the reaction p( p ,π 0 )pp from threshold to 1 GeV have been measured. The outgoing π0 was detected by a 4π neutral meson spectrometer. Our data are compared with the corresponding np→NNπ± reactions. The isoscalar partial cross sections are extracted from the relevant total cross sections. They are significant throughout the whole energy range. Below the Δ-region, energy-integrated differential cross sections show a large anisotropy difference between the neutral and charged pion channels, respectively. A partial-wave fit shows that the initial T = 0 state is dominated by the 3D1 wave in this energy region. Finally, predictions of phenomenological models give reasonable good account of the measured observables but cannot reproduce the sign of the asymmetries.

Differential cross sections for the elastic scattering of 20 and 40 MeV [pi][sup [minus]] by nuclei ranging from [sup 12]C to [sup 208]Pb are reported. Comparisons are made with the predictions of the Michigan State University (MSU) optical potential.

New precision angular distribution data for the D({gamma},{ital p}){ital n} reaction are presented for incident photon energies of 191 and 222 MeV. The difference of cross sections measured with orthogonal states of linear polarization is sensitive to the short-range behavior of the tensor interaction in models of the nuclear force. Comparisons with the Bonn and Paris potentials illustrate the sensitivity.

Measurements of the total and differential cross sections for η-meson photoproduction on 1H, 2D, and 14N liquid targets from threshold to 1.2 GeV, have been taken using the tagged Bremsstrahlung photon beam produced by the electrons extracted from the ELSA storage ring at Bonn. The reaction was identified by detecting the η decay products in the neutral meson spectrometer SPES0-2π, while the recoil baryons (proton, neutron or deuteron) were detected by a variety of large angle scintillator detectors. We present here our experimental results on the Deuterium target, both the comparison of the quasi-free proton and neutron as well as results on the coherent production. Our preliminary results for the counting rates integrated on the S11 excitation show significantly smaller figures for the neutrons than for the protons. This is consistent with an Isoscalar part of the Amplitude roughly ten times smaller than the Isovector one and also explains the very low rate of coherent deuterons observed.

Measurements of the total and differential cross sections for η-meson photoproduction on 1H, 2D, and 14N liquid targets from threshold to 1.2 GeV have been taken using the tagged Bremsstrahlung photon beam produced by the electrons extracted from the ELSA storage ring at Bonn. The reaction was identified by detecting the η decay products in the neutral meson spectrometer SPESO-2π, while the recoil baryons (proton, neutron, or deuteron) were detected by a variety of large angle scintillator detectors. We present here our experimental results on the deuterium target, both the comparison of the quasi-free proton and neutron as well as results on the coherent production. Our preliminary results for the counting rates integrated on the S11 excitation show significantly smaller figures for the neutrons than for the protons. This is consistent with an isoscalar part of the amplitude roughly ten times smaller than the isovector one and also explains the very low rate of coherent deuterons observed.

We have measured total and differential cross sections for η‐meson photo‐production on 7 cm thick 1H, 2D, and 14N liquid targets from threshold to 1.2 GeV, using the tagged Bremsstrahlung photon beam produced by the electrons extracted from the ELSA storage ring at Bonn. The photoreaction was identified by detecting the η decay products in the neutral meson spectrometer SPES0‐2π, while the recoil baryons (proton, neutron, or deuteron) were detected by a variety of large angle scintillator detectors. Some of our recent preliminary results, both theoretical and experimental, will be discussed.

The associated strangeness production in pp collisions was studied at bombarding energies of 2.3 and 2.7 GeV by detecting the outgoing K + particles with a high resolution magnetic spectrometer at forward angles up to 23.5° laboratory angle. The kaons were separated from an immense background of protons and pions by a highly resolving TOF electronics addition to vetoes from Cerenkov detectors utilizing either β differing Cerenkov light cones in lucite or different thresholds for light production in aerogel. The hyperon-nucleon missing mass spectra obtained show strong deviations from pure phase space which is ascribed to final state interactions of the pΛ and the Nσ systems. The structures found are discussed and compared with results from K − d → π − YN experiments, with theoretical calculations in the frame of OBE models, and with the prediction of sharp strange dibaryon resonances from several quark-bag models.

The Laser Electron Gamma Source (LEGS)[1] has recently begun operations at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory. At LEGS, laser light is Compton backscattered from the 2.5 GeV electrons circulating in the X-Ray storage ring of the NSLS. The backscattered photons have gamma ray energies, k < 320 MeV. The corresponding scattered electrons are detected in a tagging spectrometer which is incorporated into the storage ring. This tag provides a determination of the photon energy to ~ 5 MeV [2]. Since the laser light is polarized, and since the spin-flip amplitude in Compton backscattering is very small, the resulting polarization of the gamma-ray beam is very high.

Angular distributions for the elastic and inelastic scattering of 0.8 GeV protons from /sup 12/C, /sup 13/C, and /sup 208/Pb have been measured. Reported are data for the ground, 4.4 MeV 2/sup +/, 7.6 MeV 0/sup +/, 9.6 MeV 3/sup -/, and 14.1 MeV 4/sup +/ states of /sup 12/C; the ground, 3.1 MeV 1/2/sup +/, 3.7 MeV 3/2/sup -/, 6.9 MeV 5/2/sup +/, 7.6 MeV 5/2/sup -/, and 11.9 MeV () states of /sup 13/C; and the ground, 2.6 MeV 3/sup -/, and 3.2 MeV 5/sup -/ states of /sup 208/Pb. Analyses of the elastic angular distributions are made using the partial wave formalism and the Kerman-McManus-Thaler approach to the nucleon-nucleus optical potential; a realistic spin-orbit term is included. The inelastic transitions are analyzed within the framework of the distorted-wave Born-approximation, using transition strengths consistent with previous low-energy studies of inelastic scattering. A simple single-particle-plus-excited-core model is used for /sup 13/C. In terms of this analysis, an assignment of J/sup ..pi../ = (5/2,7/2)/sup +/ is made for the 11.9 MeV state in /sup 13/C.

J. FONG 1, T.S. BAUER, G.J. IGO, G. PAULETTA, R. RIDGE i, R. ROLFE l, j. SOUKUP 2, C.A. WHITTEN, Jr. Department of Physics, University of California, Los Angeles, CA 90024, USA G.W. HOFFMANN University of Texas, Austin, Texas 78712, and Los Alamos Scientific Laboratory, Los Alamos, NM87545, USA N. HINTZ, M. OOTHOUDT Department of Physics, University of Minnesota, Minneapolis, MN 55455, USA G. BLANPIED, R.L. LILJESTRAND Department of Physics, University of Texas at Austin, Austin, TX 78712, USA and T. KOZLOWSKI Brookhaven National Laboratory, Upton, NY 11973, USA Received 20 June 1978 The p-4He elastic cross section at 788 MeV has been measured for laboratory angles between 13.3 ° and 165.5 ° corre- sponding to a range of four-momentum-transfer, -t, from 0.11 to 4.19 GeV2/c 2 . Evidence is presented for a backward diffraction-like structure not previously observed (3.4 < -t < 4.22 GeV2/c2). In the region 1.6 < -t < -3.4 GeV2/c 2 a smooth fall off from the shoulder due to triple scattering is observed with no evidence for quadruple scattering. In the present letter we present the measurement of essentially the entire angular distribution for p-4He elastic scattering at 788 MeV. For the first time da/dt has been systematically studied in the intermediate range of angles as well as for the far backward angles, thus allowing a connection to be made between the direct amplitude and exchange amplitudes which may be important at back angles. In recent years there has been considerable exper- imental and theoretical work on the elastic scattering of protons on 4He at intermediate energies (order of 1 GeV). From an experimental point of view, this 1 Present address: Formal Computers Inc., 925 Westwood Boulevard, Los Angeles, Calif 90024. 2 Present address: Department of Physics, University of Al- berta, Edmonton T6G2J 1, Canada. elastic scattering process is relatively easy to study since the ground state of 4He is separated from a mul- tibody continuum by at least 20 MeV. With regard to theoretical interpretation of the data, the nuclear structure of 4He is reasonably well known so that proton:He elastic scattering is a good test for theo- ries of nucleon-nucleus elastic scattering at interme- diate energies. The experimental data can be used to study various effects on the reaction mechanism such as two body correlations in the nuclear wave func- tion [1], effects due to the spin dependence of the nucleon-nucleon amplitudes [2], the effects of iso- bar intermediate states [3], non-eikonal effects in the reaction mechanism [4-6], and exchange effects at backward angles [7]. Most of the past experimen- tal data, which include both cross section [8] and polarization measurements [9], have been taken for 205

Elastic cross sections for the scattering of positive and negative pions from /sup 58,60,64/Ni were measured at 30 MeV incident pion energy. A clear isotope effect was observed in the ..pi../sup -/ cross sections while no effect was observed in the ..pi../sup +/ cross sections. The cross sections were compared to predictions made by various optical model calculations. In general, both ..pi../sup +/ and ..pi../sup -/ cross sections were poorly described and the ..pi../sup -/ isotope effects were not well reproduced. Anomalous effects first observed in pionic atoms may also appear in the present data.

Elastic cross sections for the scattering of negative pions from /sup 12/C were measured at 19.5 and 30 MeV incident pion energy. At both energies the new cross sections show fair agreement with optical model predictions. At 30 MeV the new cross sections disagree at forward angles with previously measured values, while at 19.5 MeV the data represent the first report of /sup 12/C ..pi../sup -/ scattering at this energy.

The inelastic scattering of 162-MeV pions was studied over the angular range 35/sup 0/ to 100/sup 0/ in the laboratory system and the data were analyzed with a model that incorporates shell-model wave functions into a distorted-wave impulse approximation formalism. Reduced transition probabilities were obtained for low-lying levels and compared with information previously reported. In addition, evidence is obtained for theoretically predicted levels with high spin that have not been observed previously.

Angular distributions are reported for 0.8 GeV proton elastic and inelastic scattering from /sup 14/N. The data are analyzed with the optical model using a spherical Woods-Saxon potential and the distorted wave Born approximation with collective form factors.

Elastic scattering analyzing powers and differential cross sections for 800 MeV → p + 54Fe, 58,64Ni are reported. An approximately mode-independent technique is used to extract information concerning the neutron density distributions of these nuclei.

DWIA predictions and comparison with experiment are made for 650 and 800 MeV proton scattering to low lying states in 24 Mg, 26 Mg, 28 Si, 30 Si, 34 S, 40 Ca and 42 Ca. Electromagnetic constraints on proton and neutron ground-state and transition densities are used to minimize nuclear structure uncertainties. Generally good agreement with the data is seen.

New differential cross section and analyzing-power data for 800-MeV p/sub pol/ + /sup 12/C, /sup 116,124/Sn inelastic scattering to the first 2/sup +/ states are presented. A distorted-wave Born-approximation analysis which utilizes collective form factors and includes deformation of the spin-orbit potential is shown to provide a reasonable description of the analyzing-power data.

80 MeV positive and negative pions inelastically scattered from targets of /sup 12/C and /sup 40/Ca have been studied at laboratory angles between 50/sup 0/ and 120/sup 0/. Angular distributions are presented for scattering from the 4.44 MeV (2/sup +/) state in /sup 12/C, the 3.7 MeV (3/sup -/), 13.4 MeV, and 17.5 MeV states in /sup 40/Ca. The cross sections are compared with distorted wave calculations using potentials obtained from elastic scattering.

The first elastic-scattering analyzing-power (${A}_{y}$) data at 0.8 GeV are presented and discussed. Angular distributions of ${A}_{y}$ over the range 2\ifmmode^\circ\else\textdegree\fi{} to 20\ifmmode^\circ\else\textdegree\fi{} (30\ifmmode^\circ\else\textdegree\fi{} for $^{12}\mathrm{C}$) have been obtained for $^{12}\mathrm{C}$, $^{58}\mathrm{Ni}$, $^{90}\mathrm{Zr}$, and $^{208}\mathrm{Pb}$ using the high-resolution spectrometer at the Clinton P. Anderson Meson Physics Facility. The analyzing powers oscillate sharply over positive values in qualitiative agreement with expectations.

Differential cross section and analyzing power data for elastic scattering of 0.8 GeV polarized protons from 116Sn and 124Sn are analyzed in terms of a spin-dependent Kerman-McManus-Thaler formalism. Neutron matter densities and rms radii are deduced with careful attention to sources of error, and found to be in good agreement with Hartree-Fock predictions.

Analyzing powers for the exclusive pion production reaction p +d→ 3 He+π 0 have been measured at a proton beam energy of 800 MeV. The forward-angle results are in good accord with a microscopic calculation. The analyzing power is determined primarily by the Δ(1232) diagrams at this energy. Possible explanations for the large-angle discrepancies are discussed.

Angular distributions for scattering from 6Li with π+ and π− beams were measured at 100, 180 and 240 MeV incident energy. Elastic (Jp = 1+, T = 0) and inelastic (Jp = 3+, T = 0, Ex = 2.19 MeV) data were obtained over large angular ranges. The elastic results are compared to calculations within the αnp cluster model.

A distorted-wave impulse-approximation analysis of 180-MeV ..pi../sup + -/ inelastic-scattering data to the 2/sup +//sub 1/ and 3/sup -//sub 1/ states in /sup 42,44,48/Ca is used to extract the neutron and proton (alternatively, isovector and isoscalar) multipole matrix elements for exciting these states. Model-dependent errors are examined by comparing results of calculations using collective-model form factors with those using form factors fitted to electron inelastic-scattering data.

Differential cross sections for elastic and inelastic scattering of 800 MeV protons from 58 Ni have been measured to momentum transfers of 4 fm −1 . The elastic scattering data were fit using a phenomenological optical model potential. The inelastic scattering was analyzed in the distorted wave Born approximation (DWBA) to obtain deformation lengths.

The inelastic scattering of 162-MeV pions by $^{14}\mathrm{N}$ has been studied over the angular range 35\ifmmode^\circ\else\textdegree\fi{} to 115\ifmmode^\circ\else\textdegree\fi{} in the laboratory system. The data were analyzed with a model which incorporates shell model wave functions into a distorted wave impulse approximation. Reduced transition probabilities obtained for a number of low-lying states are compared to previous data to validate the model. Among new assignments and shell model descriptions presented for several higher excited states is an assignment for the yrast ${5}^{\ensuremath{-}}$ state.

Elastic scattering cross sections for ..pi../sup + -/ scattering from /sup 12/C, /sup 13/C, and /sup 14/C are presented for pion energies of 65 and 80 MeV and for scattering angles from 20/sup 0/ to 120/sup 0/. Energy dependent isospin effects are observed. The cross sections were fit with the Kisslinger potential, and the potential strength parameters show an (N-Z)/A dependence similar to that predicted by the impulse approximation at 65 MeV, but not at 80 MeV. Calculations using the Siciliano potential, which contains the explicit isospin dependence of the Lorentz-Lorenz-Ericson-Ericson effect plus isoscalar, isovector, and isotensor terms, indicate the importance and energy dependence of absorption effects. Finally a ''model independent'' parametrization of the neutron density suggests a neutron excess at the surface of /sup 13/C but not /sup 14/C.

Elastic and inelastic angular distributions for 0.8 GeV $p$ + $^{154}\mathrm{Sm}$ and $^{176}\mathrm{Yb}$ are reported and analyzed using the distorted-wave Born approximation and the coupled-channels formalism where phenomenological deformed optical potentials are used in the latter analysis. As expected, the multipole moments extracted from the optical potentials are found to be in excellent agreement with those of the charge densities as obtained from electron scattering and Coulomb excitation experiments. The analysis also clearly demonstrates that multistep processes are important at 0.8 GeV and must be included for a proper description of the experimental data.

Differential cross sections and analyzing powers for the elastic scattering of 800 MeV polarized protons from 40,42,44,48Ca are reported. A first-order, spin-dependent KMT optical potential analysis is presented from which the rms radii of the neutron densities are deduced. A comparison of these results with other determinations and with various theoretical predictions is given.

Measurements have been made of the differential cross section d/sup 2/sigma/d..cap omega..dE for the scattering of ..pi../sup + -/ from /sup 12/C and /sup 40,44,48/Ca in the energy region corresponding to quasielastic scattering. Data were taken at incident energies and laboratory angles of 180 MeV, 60/sup 0/, and 290 MeV, 60/sup 0/ and 120/sup 0/. The results are compared to a free pion-nucleon cross-section model and to a model based on pion scattering from a Fermi gas of nucleons, which incorporates free pion-nucleon cross sections. Monte Carlo methods were used for the second model, and both single scattering and multiple scattering were allowed. Several qualitative features of the data are explained by the multiple scattering calculation, but not by the free cross-section model or the single scattering model.

New and/or corrected 800 MeV $p+^{40,42,44,48}\mathrm{Ca}$ elastic angular distributions are presented. The data, together with analyzing power measurements, are analyzed to investigate the isotopic neutron and matter density differences between these four calcium isotopes. The analysis employs a local, spin-dependent form of the second order Kerman, McManus, and Thaler optical potential in which approximately model-independent forms for the neutron densities are assumed. Nucleon-nucleon amplitude uncertainties which occur at 800 MeV are taken into account in determining the empirical isotopic density differences. The deduced neutron and matter density differences are compared to the results of other intermediate energy proton and alpha particle scattering analyses and to Hartree-Fock predictions. The various empirical results are generally in good agreement with each other and with the Hartree-Fock predictions, except for $^{48}\mathrm{Ca}$ where the results obtained here and elsewhere suggest that the $^{48}\mathrm{Ca}$ neutron excess is not distributed at quite as large a radius as predicted by Hartree-Fock theory.NUCLEAR REACTIONS Proton elastic scattering cross sections; targets, $^{40,42,44,48}\mathrm{Ca}$; ${E}_{\mathrm{lab}}=800$ MeV; second order Kerman, McManus, and Thaler optical potential; neutron and matter isotopic density differences.

New, large-momentum-transfer 0.8 GeV p+/sup 208/Pb elastic analyzing power data are presented and compared to optical model predictions using the Kerman-McManus-Thaler microscopic optical potential. This comparison provides an important test of multiple scattering theories since the predictions are quite sensitive to the assumed nucleon-nucleon scattering amplitudes and are not sensitive to the details of the nuclear densities. We show that improvement in the agreement between experiment and a parameter-free theoretical prediction is obtained when the calculation includes the electromagnetic spin-orbit potential which arises from the coupling of the projectile proton's magnetic moment and the Coulomb field of the target nucleus. The sensitivity of the predicted analyzing power to the various ingredients of the theory is also investigated, and the importance of the inclusion of target-nucleon correlations (in the second-order Kerman-McManus-Thaler potential) for proper explanation of the data is discussed.

Data for the /sup 58/Ni(..pi../sup +/,2p-italic) reaction at T-italic..pi.. = 160 MeV were obtained for a number of angle pairs. The resultant angular correlations for T-italic/sub 1/+T/sub 2/>160 MeV (guaranteed pion absorption) peak at a separation angle corresponding to absorption on a deuteron at rest. However, simple estimates of initial- and final-state scatterings suggest that less than 50% of the absorption cross section arises from absorption on nucleon pairs. The data show little evidence for scattering of pions before absorption on nucleon pairs.

A coupled channels analysis of data from previous work on proton scattering from /sup 12/C at 0.8 and 1.0 GeV is presented. Calculations were performed in which the 0/sup +/,2/sup +/, and 4/sup +/ states were assumed to belong to the ground state rotational band. A deformed Woods-Saxon optical potential, with and without spin-orbit terms, was adjusted to fit the data. The multipole moments of the deformed optical potentials are related to those of the matter distributions by Satchler's theorem. Although the various values of the moments obtained here from the (p,p') data agree in sign and are approximately the same in magnitude, the values are consistently smaller for ME(2) and ME(4) than those obtained from (e,e') and from Hartree-Fock calculations.

Results of experimental measurements on protons produced at 100/sup 0/ and 158/sup 0/ from /sup 6/Li, /sup 9/Be, and /sup 181/Ta targets are presented and compared with the mass number (A), angular (theta), and momentum dependence of ''quasi-two-body scaling.''

Elastic cross sections for the scattering of positive and negative pions from /sup 58/Ni were measured at 30 MeV incident pion energy. Statistical errors of +- 3% and normalization errors of +- 6% were achieved. These data appear to confirm the theoretical construct that the physics which explains anomalously small shifts and widths in pionic atoms would be manifested in low energy pion-nucleus elastic scattering. The data show good agreement with the cross sections calculated assuming s and p partial waves are anomalous. Here anomalous refers to partial waves that are calculated from an optical potential which reproduces anomalously small level shifts and widths in pionic atoms. Conventional optical potentials do not agree as well with both the ..pi../sup +/ and ..pi../sup -/ data. Various conventional possibilities such as a larger neutron radius than proton radius in the nuclear density were tried, but these did not result in good agreement with the data.

Results of the first measurement if the excitation function of the cross section dσ/dΩ for the pion double charge exchange reaction across the (3,3) π-nucleon resonance are reported. Data from the reaction 18 O(π + , π − ) 18 Ne to the double isobaric analog state at an angle of 5° are presented which show strong structure as a function of pion energy, in contrast to the previous limited data. The measurements were made with the EPICS facility at LAMPF which was modified to allow for data-taking at small angles.

Differential cross sections for pion elastic scattering from /sup 40/Ar at 180 MeV have been analyzed within the framework of diffraction theory. Using a phenomenological determination of the underlying pion dynamics, we deduce the ratios of /sup 40/Ar to /sup 40/Ca neutron and proton densities at a radius of 4.7 fm. The results obtained show that /sup 40/Ar has a neutron skin in excess of /sup 40/Ca and the reverse for the proton skin, in agreement with Hartree-Fock densities, as well as previous determinations from ..mu.. x-rays and alpha scattering experiments.

Pion inelastic scattering on 12C to states at an excitation energy of approximately 19 MeV shows a strong enhancement at an incident pion energy near the pion-nucleon (3,3) resonance. This resonance may therefore provide a mechanism for the selective enhancement of inelastic transitions.

Angular distributions are reported for 0.8 GeV proton elastic scattering from /sup 13/C and /sup 14/N. Included are differential cross sections for p+/sup 13/C carried out to large momentum transfer (5 fm/sup -1/) using a highly enriched target (99%), and differential cross sections and analyzing powers for p+ /sup 14/N using a gas target. Spherical Woods-Saxon optical potentials are obtained from chi-squared searches on these data and are compared to the potential obtained from fitting existing /sup 12/C data.

Measurements have been made of the differential cross section d2σ/dΩdE for π+ scattered from 12C aNd 40,44,48Ca in the energy region corresponding to quasielastic scattering, using the EPICS facility at LAMPF. Data were taken at 180 Mev, 60°, And 290 Mev, 60° and 120°. Corrections were made for muon contamination, using information found on muons seen in π‐p scAttering measurements. A sample of the data is shown in Fig. 1. The rest of the for each of the two angles are very similar in character to this. Within the errors, no simple systematic effects can be seen either in the Ca isotope cross sections or in the π−/π+ ratios. These results are being studied using calculations based on pion scattering from a Fermi gas of nucleons.

The p↘+n analyzing power, Ay(θ), has been measured over the center‐of‐mass angular range 14–75 degrees.

The reactions $^{2}\mathrm{H}({\ensuremath{\pi}}^{\ensuremath{-}}, {\ensuremath{\pi}}^{\ensuremath{-}}\mathrm{p})\mathrm{n}$ and $^{2}\mathrm{H}({\ensuremath{\pi}}^{\ensuremath{-}}, {\ensuremath{\pi}}^{\ensuremath{-}}\mathrm{n})\mathrm{p}$ have been observed in a kinematically complete experiment at 150 MeV for two pairs of pion and nucleon angles corresponding to quasifree scattering. The general features of the pion energy spectrum are reproduced by the simple impulse approximation. However, both the ratio of neutron to proton production and the lower energy side of the pion energy spectra show significant departures from this model.

New preliminary results on the deuteron photodisintegration at LEGS are presented. The experimental activity at LADON is rapidly reviewed and some indication is given for the possible activity at GRAAL.

Differential cross sections for elastic scattering of 0.8-GeV protons from /sup 12/C, /sup 58/Ni, and /sup 208/Pb have been measured. Preliminary analysis of the data in terms of the Kerman-McManus-Thaler formalism with spin-dependent nucleon-nucleon amplitudes shows sensitivity to details of proton and neutron matter distributions.