The differential cross section for neutron-proton elastic scattering was measured in the diffraction region with incident-neutron momenta between 8 and 30 GeV/c. The experiment was a spark-chamber-counter experiment, conducted at the alternating-gradient synchrotron. Results are presented and compared with currently available lower energy np data and comparable energy pp data.
No description provided.
An experiment designed to study the π−p total neutral cross section and its breakdown into several channels has been performed at eleven incident pion momenta ranging from 654 to 1247 MeV/c. Angular distributions for the charge exchange π0 and for η0 production are given in terms of Legendre-polynomial expansion coefficients. Forward and backward differential cross sections are presented for the charge-exchange channel and comparisons with recent dispersion-relation predictions for the forward cross section are made.
No description provided.
Differential cross sections for neutral-pion photoproduction on hydrogen in the region of the first resonance have been measured by two independent experiments detecting the recoil protons. The results of both measurements have been combined into one set of cross sections covering the photon energy range from 200 to 440 MeV at pion c.m. angles between 50 and 160 degrees.
No description provided.
We present experimental results on K + d interactions from 865 to 1585 MeV/ c incident beam momentum. We report measurements of several K + d partial cross sections and calculate most of the others using relations derived from isospin conservation and data from other experiments. The most striking feature of the cross section data is the abrupt rise of the total single-pion-production cross section near 1000 MeV/ c . We extract isospin-0 KN partial cross sections and find a rapid quasi-two-body reaction KN → K ∗ N . As in the case of the isospin-1 K + N system, it appears that the structure around 1200 MeV/ c in the total cross section for the isospin-0 K ∗ N system is well reconstructed by the sum of three smoothly varying channel cross sections σ 0 (KN), σ 0 (KN π ) and σ 0 (KN ππ ). We study thereaction KN → K ∗ N near threshold and find that the production and decay angular distributions can be interpreted in terms of t -channel phenomena, specifically a superposition of ω, ϱ, and π exchange. As is true of the isospin-1 KΔ and K ∗ N final states, the isospin-0 K ∗ N state has a behavior near threshold which is not very different from its behavior at much higher energy.
No description provided.
A sample of approximately 250 Λp interactions has been obtained in the Λ-hyperon momentum range of about 300 to 500 MeV/ c . An enhanced Λ-hyperon production rate was obtained by exposing an internally-mounted platinum target to the incident 1.5 GeV/ c meson beam. Cross sections and angular distributions are obtained for the reactions: Λ p → Λ p, Λ p → Σ o p and Λ p → Λ p π o . In the elastic channel, no strong evidence is seen near the Σ o p threshold for the presence of a 3 S 1 resonance, which has been reported, although there is some evidence for a small enhancement in this mass region. There is evidence for the presence of P-waves and probably also D-waves above about 800 MeV/ c , but not below this momentum.
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
D(SIG)/DOMEGA IS ANALYSED IN TABLE 2 BY LEGENDRE POLYNOMIAL EXPANSION. ERRORS ADDED AS 1/SQRT(EVENTS).
Electron-proton elastic-scattering cross sections have been measured at the Stanford Linear Accelerator Center for four-momentum transfers squared q 2 from 1.0 to 25.0 (GeVc)2. The electric (GEp) and magnetic (GMp) form factors of the proton were not separated, since angular distributions were not measured at each q 2. However, values for GMp were derived assuming various relations between GEp and GMp. Several theoretical models for the behavior of the proton magnetic form factor at high values of q 2 are compared with the data.
No description provided.
Measurements of the differential cross section for the reactions π+p→K+Σ+ and π+p→K+Y*+(1385) are reported at 3.5, 3.75, 4.0, 4.25, 4.5, 4.75, 5.0, 6.0, 10.0, and 14.0 GeV/c. Polarization in π+p→K+Σ+ is also reported at 6.0, 10.0, and 14.0 GeV/c. At small |t|, the cross section for π+p→K+Σ+ is well described by an exponential Aebt with slopes in the range b≈8−10 (GeV/c)−2; for |t|>0.5 (GeV/c)2 this slope decreases considerably. The cross section for π+p→K+Y*+(1385) is well described for |t|>0.2 (GeV/c)2 by a single exponential of slope about half that for π+p→K+Σ+; there is no break near |t|>0.5 (GeV/c)2. We observe a dip in this cross section near t=0. The polarization in π+p→K+Σ+ is consistent with zero for |t|<0.4 (GeV/c)2 and becomes large and positive for larger |t|.
No description provided.
From 2728 events of 205-GeV pp interactions found in 15 000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.5±1.1 mb was measured. The mean charged-particle multiplicity for inelastic pp collisions was measured to be 7.65±0.17. The prong distribution from 2 to 22 prongs is broader than a Poisson distribution and has a width parameter f2−=〈n−(n−−1)〉−〈n−〉2=0.95±0.21.
We present results on vector-meson photoproduction via γp→Vp in the LBL-SLAC 82-in. hydrogen bubble chamber exposed to a linearly polarized photon beam at 2.8, 4.7, and 9.3 GeV. We find ρ0 production to have the characteristics of a diffractive process, i.e., a cross section decreasing slowly with energy and a differential cross section with slope of ∼ 6.5 GeV−2. Within errors the ρ0 production amplitudes are entirely due to natural-parity exchange. s-channel helicity is conserved to a high degree in the γ→ρ0 transition. We find evidence for small helicity-flip amplitudes for ππ pairs in the ρ0 region. Photoproduction of ω mesons is separated into its natural- (σN) and unnatural- (σU) parity-exchange contributions. The Eγ and t dependence and the spin density matrix of the unnatural-parity-exchange contribution are consistent with a one-pion-exchange process. The natural-parity-exchange part has characteristics similar to ρ0 production. At 9.3 GeV the ratio of σ(ρ0) to σN(ω) is ∼ 7. The slope of the φ differential cross section is ∼ 4.5 GeV−2, smaller than that of ρ0 and ω production. Natural-parity exchange is the main contributor to φ production. No evidence for higher-mass vector mesons is found in ππ, πππ, or KK¯ final states. The s and t dependences of Compton scattering as calculated from ρ, ω, and φ photoproduction using vector-meson dominance agree with experiment, but the predicted Compton cross section is too small by a factor of 2.
CALCULATED BY THE METHOD OF MOMENTS IN THE OMEGA MASS REGION. BACKGROUND NOT SUBTRACTED (ESTIMATED TO BE <5 PCT).
The polarization parameter in π±p elastic scattering has been measured at several momenta in the range 2.50-5.15 GeV/c pion laboratory momentum and covering the range in t approximately from -0.2 to -2.0(GeV/c)2. The data show positive polarization for π±p scattering, having a dip near t=−0.6 (GeV/c)2 and becoming relatively large at greater values of −t. The results for π+ and π− scattering are approximately equal in magnitude but of opposite sign. The data have been analyzed to separate the components, which are symmetric and antisymmetric with respect to pion charge, and to show both the t and s dependence of each part.
No description provided.
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