A comparison is made of the properties and production mechanisms of the π + ω and K − ω systems produced in the reactions π + p → π + ω p at 4, 5, 8 and 16 GeV/ c and K − p → K − ω p at 10 and 16 GeV/ c . In the π + ω case apeak is observed at 1.23 GeV (the B meson), while the K − ω mass distribution has a threshold enhancement. The cross section of the low mass (<2.0 GeV) π + ω system falls as p lab −2 , while that of the low mass (<2.0 GeV) K − ω system is almost constant with energy, indicating diffractive production of the K − ω system, but not of the πω system. Using a modified version of the Illinois partial-wave analysis program, it is found that the K − ω system is dominantly produced in the J P = 1 + state with small contributions of 0 − and 2 + , mainly by natural parity exchange - as is found for reactions such as K − p → (K − π + π − )p which are predominantly diffractive. For the π + ω system in the B mass region, J P = 1 + states, produced mainly by natural parity exchange are found; the contributions of 0 − P, 1 − P, 2 − P and 2 + D are consistent with zero. The 1 + D state occurs in the π + ω case but not in the K − ω system, nor in the K ππ − system produced in the K − p → K ππ p reaction.

The missing-mass technique has been used to study the spectra of neutral mesons produced by 2- and 3-Gev protons in the reaction p+d→He3+x0. Cross sections (dσdΩc.m.) of about 10−34 cm2/sr were observed for the π, η, and ω for 3-GeV protons. A peak with a much smaller cross section was observed at a mass of 956 MeV. We have tentatively identified this peak as the η′. Cross sections for the π and η were nearly a factor of 10 larger at 2 GeV than at 3 GeV. Deviations from simple phase space were observed near the two-pion threshold in both 2-GeV and 3-GeV data. Details of the experimental method and of the results are presented.

Experimental data on dd small-angle elastic scattering in the Coulomb interference region are analysed to yield the dd scattering amplitude. This amplitude is then expressed in terms of the nucleon-nucleon scattering amplitudes and the Glauber correction. The value for the nn scattering amplitude found is shown to be in good agreement with the pp amplitude.

Measurements of K + p elastic scattering have been carried out at 13 momenta between 432 MeV/ c and 939 MeV/ c using spark chambers. The data establish unambiguously the constructive interference of the Coulomb and nuclear amplitudes at 432 MeV/ c . The elastic cross section is found to be independent of momentum through the range covered. The phase shifts for S, P, D and F waves are obtained in an energy dependent analysis in which higher waves are held at theoretical values. The initial behaviour ofthe P, D and F amplitudes is quite close to that predicted by the calculation of the peripheral partial waves. Only the P3 and D5 amplitudes become strikingly different with increasing momentum.

Results on the elastic K − π − scattering have been obtained from a study of the K − π − system in 15 000 events of the type K − p→K − π − p π + at a K − beam momentum of 4.25 GeV/ c . The on-mass-shell values of the spherical harmonic moments of the K − π − scattering angular distribution and the K − π − elastic cross section have been obtained by extrapolation to the pion pole. From these values we determined the s- and p-wave phase shifts δ 0 3 and δ 1 3 as a function of the effective mass of the K − π − system between threshold and 1.25 GeV/ c 2 . The value of | δ 0 3 | is smaller than 17° for all mass values and the existence of a p-wave cannot be neglected. At m K − π − = 1.18 GeV/ c 2 there are two solutions for the phase shifts. On the average, the cross section of the K − π − elastic scattering over the region of the effective mass considered amounts to approximately 2.5 mb.

The v and v nucleon total cross-sections have been determined as a function of energy using a sample of 2500 v and 950 v event. The results are compared with predictions of scaling and charge symmetry hypotheses.

We report our first measurements of the polarization in the elastic scattering of negative pions from polarized protons at an incident pion momentum of 40 GeV/ c . The momentum-transfer region covered was 0.08 < | t | < 1.3 (GeV/ c ) 2 . The angular distribution of the polarization exhibits a first minimum of ∼ − 5% and the well-known zero around t ≈ − 0.6 (GeV/ c ) 2 . The energy variation of the first minimum (at around t = − 0.2) may be expressed in a simple form, P avr = −(0.48±0.06) s −0.52±0.05 .

We have measured cross section for γ , K S °, Λ and Λ production at 102 GeV/ c and find: σ ( γ ) = 170 ± 16 mb ., σ ( K S °) = 4.6 ± 0.5 mb ., σ ( Λ ) = 3.2 ± 0.4 mb ., and σ( Λ ) = 0.23 ± 0.10 mb. Both 〈 n π °〉 and 〈 n Ks °〉 appear to rise linearly with n - while the ratio 〈 n Ks °〉/〈 n π °〉 is approximately independent of n - . The integrated invariant cross section as a function of x as well as d σ /d y and d σ /d p T 2 are presented and compared with other data.

The spin rotation parameter R in elastic proton-proton scattering has been determined at incident momenta 6 and 16 GeV/ c in the interval from t = −0.18 (GeV/ c ) 2 to −0.54 (GeV/ c ) 2 . R pp at 16 GeV/ c is close to the val obtained for R in π − p elastic scattering at the same incident momentum. Equality of R pp ( s , t ) and R π p ( s , t ) is expected if Pomeron exchange dominates and if factorization holds. The t -dependence of R at 16 GeV/ c is consistent with weak helicity flip.

We have measured the total inelastic cross section (σinel) and charged-particle multiplicities obtained in pp collisions at 405 GeV/c. The data are from a preliminary 12 000-picture bubble-chamber exposure. We find σinel=32.8±1.0 mb; the low moments of the multiplicity distribution for negative particles are 〈n−〉=3.50±0.07, D−=2.37±0.05, f2−=2.1±0.2, and f3−=0.1±0.9. We also present updated results at 102 GeV/c.

A bubble-chamber study is presented of a 10 events/μb experiment using K − mesons of 4.25 GeV/ c incident momentum. Differential and total cross sections are determined for 7 different reactions: K − p → K 0 n ( la ), → π 0 Λ ( lb ), → ηΛ ( lc ), → η′Λ ( ld ), → π − Σ ( le ), → π + Σ − ( lf ), K + Ξ − ( lg ) . The experimental characteristics in d σ /d t of each reaction are described: (la) shows a levelling off at t = 0 (GeV/ c ) 2 , a break at t = −0.6 (GeV/ c ) 2 and no backward events, (lb) d σ /d t has a smooth behaviour and a measurable backward component with an indication of a dip at u = −0.2 (GeV/ c ) 2 , (1c) d σ /d t shows a dip in the region between t ≈ −0.2 and −0.4 (GeV/ c ) 2 , (ld) d σ /d t has a smooth behaviour; neither this reaction nor the preceding one shows a clear evidence for backward events, (le) d σ /d t has a break at t = −0.5 (GeV/ c ) 2 ; there is a significant cross section in the backward region; (lf) and (lg) show mainly backward production. The polarization of the hyperon is measured in the reactions (lb), (lc), (ld) and (le) in the forward production peak. The statistics do not allow the detection of a definite structure in the polarization but the sign and magnitude are determined. An interpretation of the results is given in terms of a dual Regge model, including the effects of absorption as elaborated recently by several authors.

In an experiment with the CERN 2m deuterium bubble chamber the reaction K + d→K o pp (1) and the related reaction K + n→K o p (2) are studied at an incident momentum of 4.6 GeV/ c . The cross section for the latter reaction is found to be slightly larger than the cross section for the reaction K − p → K o n at the same energy. The corresponding differential cross sections agree within the rather large uncertainties. The forward amplitude for reaction (2) is predominantly real. Moreover, the total and forward differential charge exchange cross section values are compatible with those predicted on the basis of an SU (3) sum rule. A comparison of the K ± -charge exchange differential cross sections with the predictions of a Regge pole model is also presented.

We present data from a spark-chamber study of K+p elastic scattering between 432 and 939 MeV/c, over the range −0.6<cosθc.m.<+0.7. With measurements at 13 momenta, and between 2000 events at the lowest momentum and 5000 events at the highest momentum, there is a major improvement over previous data. The elastic cross sections deduced from the differential cross sections are almost independent of momentum through the range covered. The data are inconsistent with counter measurements of the total cross section which suggest a sharp shoulder in the cross section at about 700 MeV/c.

We present preliminary results from a sample of ∼ 1200 events obtained from an exposure of the 30-in. Argonne National Laboratory—National Accelerator Laboratory liquid-hydrogen bubble chamber to 102-GeVc protons. The elastic and total inelastic cross sections are respectively 6.9 ± 1.0 and 32.8 ± 1.1 mb. The parameters of the multiplicity distribution for negative tracks are 〈n−〉=2.17±0.07, D−2=〈n−2〉−〈n−〉2=2.56±0.12, and f2−=D−2−〈n−〉=0.39±0.10.

The spin rotation parameter R has been measured at CERN, for π ± p at 6 GeV c and for π − p at 16 GeV c , with t ranging from −0.19 to −0.51 ( GeV c ) 2 . The parameter A was measured for π − p at 6 GeV c in the interval between t =−0.19 and minus;0.41 ( GeV c ) 2 . The averaged values are the following; R (+6) =−0.08±0.04, R (−6) =−0.23±0.05 and R (−16) =−0.23±0.05. The values obtained for A are close to +1.

Results are presented on effective-mass distributions, differentisl cross sections and longitudinal c.m. momentum distributions for the channels K − p → K − p π o , K o p π − and K − π + n , obtained from a sample of approximately 28 000 inelastic two-pronged interactions at 4.2 GeV/ c incident momentum. The results are in satisfactory agreement with the prediction of a generalized Veneziano-model corrected for (non-dual) π -and pomeron exchange. For the channel K − pπ o pomeron exchange contributes about 20% of the cross section. In the channel K − π + n the dual, pion and pomeron contributions are responsible for resp. 15%, 65% and 20% of the total cross section.

As a partial result of an analysis of K + d interactions at 3 GeV/ c produced in the 81 cm Saclay bubble chamber, we present data on K + differential cross sections for the following reactions: K + d → K + d, K + d → K + pn, K + d → K 0 pp . A set of parameters describing the K + n elastic scattering has been obtained from a simulataneous fit, based on the Glauber model. to the three experimental differential cross sections and to the K + d total cross section, giving α n = 1.7 ± 0.5 GeV −2 for the slope α n of the differential cross section, and ρ n = −0.16 ± 0.3 for the ratio of the real to the imaginary part of the forward scattering amplitude. The D-wave function of the deuteron has been found to give a non-negligible contribution to the coherent reaction.

The polarization parameter in proton-proton scattering has been measured at incident proton kinetic energies of 1.7, 2.85, 3.5, 4.0, 5.05, and 6.15 BeV and for four-momentum transfer squared between 0.1 and 1.0 (BeV/c)2. The experiment was done with an unpolarized proton beam from the Bevatron striking a polarized proton target. Both final-state protons were detected in coincidence and the asymmetry in counting rate for target protons polarized parallel and antiparallel to the scattering normal was measured. The maximum polarization was observed to decrease from 0.4 at 1.7 BeV to 0.2 at 6.1 BeV. The maximum of the polarization at all energies studied occurs at a four-momentum transfer squared of 0.3 to 0.4 (BeV/c)2.

The ratio of the yields of negative and positive pions photoproduced in deuterium has been measured at six photon energies between 500 and 1000 Mev and at seven angles between 20° and 160° in the center-of-momentum system of the photon and target nucleon. Pions were selected with a magnetic spectrometer and identified using momentum and specific ionization in a scintillation counter telescope. The spectator model of the deuteron was used to identify the photon energy. Statistical errors assigned to the π−π+ ratio range between five and fifteen percent. The results of the present experiment join smoothly with the low-energy π−π+ ratios obtained by Sands et al. At high energies the π−π+ ratio varies from 0.5 at forward angles and energies near 900 Mev to 2.5 at 160° c.m. and energies 600 to 800 Mev. The cross sections for π− photo-production from neutrons have been derived from the π−π+ ratio and the CalTech π+ photoproduction data. The angular distributions for π− production are considerably different from those for π+; there is, for example, a systematic increase at the most backward angles. The energy dependence of the total cross section for π− is similar to that for π+, although the second resonance peak occurs at a slightly lower energy, and at 900 and 1000 Mev the π− cross section is smaller by a factor 1.6. A comparison is made of the cross sections for π+ photoproduction from hydrogen and deuterium, although the accuracy of this comparison is not high.

The target asymmetry T, recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive $\pi ^0$ and $\eta $ photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the $\gamma p \rightarrow \pi ^0 p$ and $\gamma p \rightarrow \eta p$ reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the $\eta n$ system at $W = 1.68\ \textrm{GeV}$. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the $S_{11}(1535)$ and $S_{11}(1650)$ resonances within the $S_{11}$-partial wave.