None
INCLUDING DATA FROM PREVIOUS WORK OF THIS GROUP.
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.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
Excitation functions AN(pp,Θc.m.) of the analyzing power in pp→ elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta pp between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30°≤Θc.m.≤90° using the recirculating beam of the proton storage ring COSY during acceleration. The resulting excitation functions and angular distributions of high internal consistency have significant impact on the recent phase shift solution SAID SP99, in particular, on the spin triplet phase shifts between 1000 and 1800 MeV, and demonstrate the limited predictive power of single-energy phase shift solutions at these energies.
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
The pp analyzing power was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ CM from 28° to ≅50° and complete our previous measurements from 45 ° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from θ CM = 28° (at the lower energies) or θ CM = 18° (at the higher energies) to θ CM > 90°. The shape of the angular distribution A oono ( pp ) = ƒ(θ CM ) changes considerably with increasing energy. The new data show the onset of a characteristic t -dependence of the analyzing power, with a minimum at − t ≅ 1.0 (GeV/ c ) 2 followed by a second maximum at − t ≅ 1.5 (GeV/ c ) 2 . This structure is present at all energies, from kinematic threshold to 200 GeV.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
The energy dependence of the pp elastic analyzing power has been measured using an internal target during polarized beam acceleration. The data were obtained in incident-energy steps varying from 4 to 17 MeV over an energy range from 0.5 to 2.0 GeV. The statistical uncertainty of the analyzing power is typically less than 0.01. A narrow structure is observed around 2.17 GeV in the two-proton invariant mass distribution. A possible explanation for the structure with narrow resonances is discussed.
Statistical errors only.
The ratio of the analysing powers for quasi-elastic pp scattering in carbon and for elastic scattering on free protons was measured fromT = 0.52 to 2.8 GeV by scattering of the SATURNE II polarized proton beam on carbon and CH2. It was found to have a maximum at about 0.8 GeV. The energy dependence for quasielastic scattering on carbon had not been measured before above 1 GeV. The observed effect was not expected from simple models.
No description provided.
We measured d σ d t(90° cm ) for ↑+ p ↑→ p + p from 1.75 to 5.5 GeV/ c , using the Argonne zero-gradient synchrotron 70% polarized proton beam and a 70% polarized proton target. We found that the spin-spin correlation parameter. A nn , equals 60% at low energy, then drops sharply to about 10% near 3.5 GeV/ c , and remains constant up to 5.5 GeV/ c .
ANALYZING POWER. QUOTED ERRORS DUE TO 4.3 PCT POINT TO POINT RELATIVE ERROR.
THE SPIN-SPIN CORRELATION PARAMETER CNN IS NOW DENOTED BY ANN ACCORDING TO THE NEW ANN ARBOR CONVENTION.
The spin-dependent observables N 0 s ″ kn , D 0 n 0 n and K 0 s ″ k 0 in pp elastic scattering were measured at nine energies between 0.84 and 2.1 GeV using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The beam polarization was oriented longitudinally and the target polarization was oriented vertically. Precession of the recoil particle spin in the target holding field introduces a small contribution from other parameters. The present results for K 0 s ″ k 0 and D 0 n 0 n agree with our previous measurements of the same observables carried out in different beam and target spin configurations as well as with previously existing measurements. The observable N 0 s ″ kn had not been measured previously above 0.58 GeV. Below 1.3 GeV our data are compared with the predictions of the Saclay-Geneva phase shift analysis. The new results will considerably affect the phase shift analysis solutions and will contribute to their extension towards higher energies.
No description provided.
No description provided.
No description provided.
The spin correlation parameter A ookk in pp elastic scattering was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ CM from 28° to ⋍ 50° and complete our previous measurements from 45° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from θ CM = 28° (at the lower energies) or θ CM = 18° (at the higher energies) to θ CM > 90°. The shape of the angular distribution A ookk (pp) = f ( θ CM ) changes considerably between in our energy region.
No description provided.
No description provided.
No description provided.
The spin dependent observables N 0s n ″ k , K 0s″s0 and D 0s″0k in pp elastic scattering were measured at 11 energies between 0.84 and 2.7 GeV using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The beam polarization was oriented in the vertical plane, the target polarization was oriented along the incident beam direction. Below 1 GeV the present data agree with previously existing measurements. Below 1.3 GeV they are compared with the predictions of the Saclay-Geneva phase shift analysis. The results will improve the phase shift analysis solutions and will contribute to their extensions towards higher energies. Together with our previous results the data allow a direct reconstruction of the pp elastic matrix over the energy region from 0.84 too 2.7 GeV.
No description provided.
No description provided.
No description provided.
The spin correlation parameter A oosk was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ CM from 28° to ⋍ 50°. At 0.88 GeV they complete our previous measurements from 45° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from gq CM = 28° (at lower energies) or θ CM = 18° (at higher energies) to θ CM > 90°. The shape of the angular distribution A oosk (pp) = ƒ(θ CM ) changes considerably between 1.8 and 2.4 GeV.
No description provided.
No description provided.
No description provided.
The spin-dependent observables N 0 nkk , D 0 s ″0 k and K 0 s ″ k 0 in pp elastic scattering were measured at 11 energies between 0.84 and 2.7 GeV using the SATURNE II polarized proton beam and the Saclay frozen-spin polarized target. The beam and target polarizations were oriented longitudinally. Precession of the recoil-particle spin in the target holding field introduces small contributions from other parameters. The present data agree with the few previously existing measurements. Below 1.3 GeV our data are compared with the predictions of the Saclay-Geneva phase-shift analysis. The new results will considerably affect the phase-shift analysis solutions and will contribute to their extension towards higher energies.
No description provided.
No description provided.
No description provided.
The spin correlation parameters A 00 kk and A 00 sk were measured at 0.874, 0.934, 1.095, 1.295, 1.596, 1.796, 2.096, and 2.396 GeV, using the SATURNE II polarized proton beam and tha Saclay frozen spin polarized target. The present results for beam-target spin correlations obtained during measurements of three-spin index observables confirm, in particular, relatively large positive values of A 00 sk at certain energies and angles, as was shown in previously published data from a dedicated experiment.
No description provided.
No description provided.
No description provided.
The spin-dependent observables D 0 n 0 n and K 0 nn 0 in pp elastic scattering were measured at 11 energies between 0.84 and 2.7 GeV using the SATURNE II polarized proton beam and the Saclay frozen-spin polarized target. The beam and target polarizations were oriented along the normal to the scattering plane. Below 1 GeV the present data agree with previously existing measurements. Below 1.3 GeV they are compared with the predictions of the Saclay-Geneva phase-shift analysis. The results will improve the phase-shift analysis solutions and will contribute to their extension towards higher energies.
No description provided.
No description provided.
No description provided.
We have measured π±p and pp elastic differential cross sections in the range |cosθc.m.|<0.35 for incident momenta from 2 to 9.7 GeV/c for π−p and pp and from 2 to 6.3 GeV/c for π+p. We find that the fixed-c.m.-angle πp differential cross sections cannot be described as simple functions of s. The data are compared to the energy and angular dependence predicted by the constituent model of Gunion, Brodsky, and Blankenbecler.
No description provided.
No description provided.
No description provided.
We have measured the differential cross section for π−p elastic scattering at 180° in steps of 0.10 GeV/c or less in the region P0=1.6 to 5.3 GeV/c. We detected elastic scattering events, from protons in a liquid H2 target, with a double spectrometer consisting of magnets and scintillation counters in coincidence. The incident π− beam was counted by scintillation counters. The cross section was found to have considerable structure. This may be interpreted as interference between the resonant amplitudes and the nonresonant or background amplitude. Very strong destructive interference occurs around P0=2.15 GeV/c, where the cross section drops almost two orders of magnitude in passing through the N*(2190). Another interesting feature of the data is a large narrow peak in the cross section at P0=5.12 GeV/c, providing firm evidence for the existence of a nucleon resonance with a mass of 3245±10 MeV. This N*(3245) has a full width of less than 35 MeV, which is about 1% of its mass. From this experiment we were able to determine the parity and the quantity χ(J+12) for each N* resonance, where χ is the elasticity and J is the spin of the resonance.
No description provided.
No description provided.
No description provided.
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 errors are statistical.
The differential cross sections for π−p elastic scattering over the angular range 155° to 177° in the center of mass have been measured at 33 incident-pion momenta in the range 600 to 1280 MeV/c. Angular distributions are presented. The extrapolated differential cross sections at 180° show considerable structure, in particular a dip near 1150 MeV/c. In general the near-180° cross sections do not agree with existing phase shift solutions above 1000 MeV/c
INTERPOLATED DATA.
INTERPOLATED DATA.
INTERPOLATED DATA.
Results of a spark chamber experiment on elastic scattering of pions on protons are presented and analyzed. The processes studied were π+p at 2.92 GeV/c, and π−p at 3.15, 4.13, and 4.95 GeV/c. The data are fitted to an exponential function of the four-momentum transfer, t, in several different ways in attempts to explore systematic energy and angular dependences. No shrinkage of the diffraction peak is seen in comparing the coefficients of a linear exponential fit for |t|<0.4 (GeV/c)2; at larger |t|, however, the cross section falls off with increasing energy. The large-angle differential cross section is examined for structure and is compared with all other large angle scattering data. The results are compared with proton-proton scattering data over the same energy range and substantial differences between the two processes are evident.
No description provided.
No description provided.
No description provided.
The backward angular distributions obtained in an experiment at the Zero Gradient Synchrotron of Argonne National Laboratory were used to systematically study the energy dependence of the 180° differential cross section for π+p elastic scattering in the center-of-mass energy region from 2159 to 3487 MeV. At each of 38 incident pion momenta between 2.0 and 6.0 GeV/c, a focusing spectrometer and scintillation counter hodoscopes were used to obtain differential cross sections for typically five pion scattering angles from 141° to 173° in the laboratory. Values for dσdΩ at 180° were then obtained by extrapolation. A resonance model and an interference model were used to perform fits to the energy dependence of dσdΩ (180°). Both models led to good fits to our data and yielded values for the masses, widths, parities, and the product of spin and elasticity for the Δ(2200), Δ(2420), Δ(2850), and Δ(3230) resonances. Our data confirm the existence of the Δ(3230) and require the negative-parity Δ(2200).
No description provided.
No description provided.
No description provided.
The energy dependence of the differential cross section for $\pi^+ p$ elastic scattering at a c.m. angle near 174 ° has been measured. The momentum range of incident $\pi^+$ was 2.06-4.70 GeV/c. On this energy dependence one can see a structure, i.e. maxima corresponding to the baryon resonances $\Delta(2420)$ and $\Delta(2840)$. The structure is used for determination of the parities of these resonances.
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
We present a series of numerical and statistical techniques for interpolating and combining ("amalgamating") data from meson-nucleon scattering experiments. These techniques have been extensively applied to πp elastic and charge-exchange differential-cross-section and polarization data in the resonance region. The amalgamation is done by fitting a momentum- and angle-dependent interpolating surface to the data over a moderately narrow momentum range, typically ∼150 MeV/c, using the interpolating surface to shift data in a narrower central momentum region into fixed angular bins at a predetermined central momentum, and then statistically combining the data in each bin. The fitting procedure takes into account normalization errors, momentum calibration errors, momentum resolution, electromagnetic corrections, threshold structure, and inconsistencies among the data. The full covariance matrix of the amalgamated data is calculated, including contributions of statistical error, systematic error, and interpolation error. Techniques are presented for extracting from the covariance matrix information on the collective statistical fluctuations which correlate the errors of the amalgamated data. These fluctuations are described in terms of "correlation vectors" which facilitate the use of the amalgamated data as input for resonance-region phenomenology.
No description provided.
No description provided.
No description provided.
Forum