Differential cross sections for the exclusive reaction p⃗p→ppη observed via the η→π+π−π0 decay channel have been measured at Tbeam=2.15GeV, 2.50GeV, and 2.85GeV (excess energies 324MeV, 412MeV, and 554MeV). The influence of the N(1535)S11 resonance is clearly seen in the invariant mass and momentum dependent differential cross sections. The extracted resonance parameters are compatible with existing data. No significant evidence for further resonance contributions has been found. In addition, angular distributions of the ppη final state have been measured. The polar angle distribution of the η shows an anisotropy with respect to the beam axis for the lowest beam energy, which vanishes for the higher energies. The sign of this anisotropy is negative and expected to be sensitive to the dominant production mechanism. In contrast, the proton polar angle in the pp rest frame tends to be more strongly aligned along the beam axis with increasing beam energy. The analyzing power Ay is compatible with zero for all beam energies.
Differential cross section for incident kinetic energy 2.15 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.
Differential cross section for incident kinetic energy 2.50 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.
Differential cross section for incident kinetic energy 2.85 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.
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.
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Measurements at 19 beam kinetic energies between 1795 and 2235 MeV are reported for the pp elastic scattering spin correlation parameter A00nn=ANN=CNN. The c.m. angular range is typically 60–100°. The measurements were performed at Saturne II with a vertically polarized beam and target (transverse to the beam direction and scattering plane), a magnetic spectrometer and a recoil detector, both instrumented with multiwire proportional chambers, and beam polarimeters. These results are compared to previous data from Saturne II and elsewhere.
Measured values of CNN at EKIN 1795 Mev.. Fractional systematic uncertainty in the absolute beam and target polarization is +-0.110.
Measured values of CNN at EKIN 1845 Mev.. Fractional systematic uncertainty in the absolute beam and target polarization is +-0.073.
Measured values of CNN at EKIN 1935 Mev.. Fractional systematic uncertainty in the absolute beam and target polarization is +-0.095.
The pp elastic scattering analyzing power was measured in small energy steps in the vicinity of the accelerator depolarizing resonance $\gamma G= 6 $ at 2.202 GeV.
Analysing power measurements in P P elastic scattering LEN(C=CU) is the length of CU degrader thickness used in each group.
Analysing power measurements in P P elastic scattering LEN(C=CU) is the length of CU degrader thickness used in each group.
Analysing power measurements in P P elastic scattering LEN(C=CU) is the length of CU degrader thickness used in each group.
Experimental results are presented for the pp elastic-scattering single spin observable Aoono=Aooon=AN=P, or the analyzing power, at 19 beam kinetic energies between 1795 and 2235 MeV. The typical c.m. angular range is 60–100°. The measurements were performed at Saturne II with a vertically polarized beam and target (transverse to the beam direction and scattering plane), a magnetic spectrometer and a recoil detector, both instrumented with multiwire proportional chambers, and beam polarimeters.
Measurement values of the P P analysing power at kinetic energy 1.795 GeV. The relative and additive systematic errors are +- 0.106 and 0.003.
Measurement values of the P P analysing power at kinetic energy 1.845 GeV. The relative and additive systematic errors are +- 0.068 and 0.001.
Measurement values of the P P analysing power at kinetic energy 1.935 GeV. The relative and additive systematic errors are +- 0.091 and 0.003.
A polarized proton beam extracted from SATURNE II and the Saclay polarized proton target were used to measure the rescattering observables$K_{onno}$and
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A polarized proton beam extracted from SATURNE II was scattered on an unpolarized CH 2 target. The angular distribution of the beam analyzing power A oono was measured at large angles from 1.98 to 2.8 GeV and at 0.80 GeV nominal beam kinetic energy. The same observable was determined at the fixed mean laboratory angle of 13.9° in the same energy range. Both measurements are by-products of an experiment measuring the spin correlation parameter A oon .
Analysing power measurements at a fixed laboratory angle of 13.9 degrees.
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The beam energy and invariant mass dependence of the dielectron yield in p + d interactions relative to the yield in p + p interactions is presented for incident kinetic energies from 1.0–4.9 GeV. The ratio of the yield in p + d interactions to that in p + p interactions decreases from 10.5±1.6 at 1.0 GeV to 1.96±0.08 at 4.9 GeV for electron pairs with invariant masses ⩾ 0.15 GeV/ c 2 . The large ratio at 1.0 GeV suggests that dielectron production in the p + d system is dominated by a p + n process. The beam energy dependence of the ratio indicates that this p + n contribution decreases with respect to the other dielectron sources as the incident energy is increased.
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Data on multiplicities of charged particles produced in proton-nucleus and nucleus-nucleus collisions at 200 GeV per nucleon are presented. It is shown that the mean multiplicity of negative particles is proportional to the mean number of nucleons participating in the collision both for nucleus-nucleus and proton-nucleus collisions. The apparent consistency of pion multiplicity data with the assumption of an incoherent superposition of nucleon-nucleon collisions is critically discussed.
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We have measured the difference between the pp total cross sections for parallel and antiparallel longitudinal spin states at beam momenta of 2.75, 2.92, 3.25, and 3.48 GeV/c. These results reveal possible new structure in this momentum range.
Data read from graph. Statistical errors only.