The p̄ 3 He annihilation cross section is measured for the first time in the momentum interval (50÷60) MeV/ c . About 9000 pictures collected by the Streamer Chamber Collaboration (PS179) at LEAR–CERN have been scanned. Six events are found, corresponding to σ ann =1850±700 mb. The result is compared to the set of measurements presently available in the region of low p̄ momentum.
The mean beam momentum at the center of the fiducial volume = 55 MeV.
Tensor polarization observables (t20, t21 and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)^2. The experiment was performed at the Jefferson Laboratory in Hall C using the electron HMS Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q^2 the deuteron charge form factors G_C and G_Q. They are in good agreement with relativistic calculations and disagree with pQCD predictions.
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Using a primary beam of 40 Ar at ∼1A GeV impinging on a Be target, the production cross-sections of light neutron-rich fragments from projectile fragmentation were measured at the projectile-fragment separator FRS at GSI. The experimental cross-sections were obtained for isotopes of the elements B to F both close to stability and near the neutron drip line. These data are compared to the results of the empirical parametrization EPAX. We also compare the results to those measured previously at LBL. As an additional result, the particle instability of 26 O has been confirmed.
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A double scattering experiment, performed at the Paul-Scherrer-Institut (PSI), has measured a large variety of spin observables for free np elastic scattering from 260 to 535 MeV in the c.m. angle ran
Relative uncertainties on the carbon polarimeter analysing power (AC).
Relative uncertainty in the beam polarisation (PB).
Measurements of DNN with statistical errors only.
The spin correlation parameters$A_{oonn}, A_{ooss}, A_{oosk}, A_{ookk}$and the analyzing power$A_{oono}$have been measured i
Values of the coefficients for the linear combinations of the spin correlation parameters Cpq measurements for the four different beam and target polarisation orientations. For the (z,z) and (y,y) configurations the coefficients are identical for all incident kinetic energies.
Measurement of the analysing power. Statistical errors only are shown. For the systematic errors see the systematics section above. Note that there are two overlapping angular settings.
Measurements of the spin correlation parameter CNN. Statistical errors onlyare shown. For the systematics see the systematic section above. Note the two overlapping angular settings.
The processes$e^+e^-\rightarrow\eta\gamma, \pi^0\gamma\rightarrow 3\gamma$were studied in the SND experiment at the VEPP-2M collider in the energy region of the
Results of energy scan of the cross section.
Cross sections for PHI production and decay into the two states from a fit to the data at the peak.
The total cross section of the p d -> p d eta reaction has been measured at two energies near threshold by detecting the final proton and deuteron in a magneti spectrometer. The values are somewhat larger than expected on the basis of two simple theoretical estimates.
The first quoted error includes statistical and normalization uncertainties, the scond is that induced by the uncertainty in the excess energy.
In collisions of 40-GeV/c antiprotons with D, Li, C, S, Cu, and Pb nuclei, mean multiplicities of various secondary particles are investigated as functions of the mass number A. The mass-number dependence of the mean multiplicities of positively charged particles suggests that the effect of intranuclear cascades is strong for the emission of Λ hyperons, but that it is relatively weak for the emission of either K 0 or \(\bar \Lambda \). Also measured are the yields of various neutral strange particles with respect to those of charged secondaries.
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The antineutron–proton total cross section has been measured in the low momentum range 50–400 MeV/ c (below 100 MeV/ c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/ c . A dominance of the isospin I =0 channel over the I =1 one at low energy is clearly deduced.
Measured values of the total cross section.
Polarization measurements in the A(p, 2p)B reactions on 6Li, 7Li, and 28Si nuclei at a proton-beam energy of 1 GeV were performed in a kinematically complete experiment. By using a two-arm magnetic spectrometer, two secondary protons were recorded in coincidence at asymmetric scattering angles of θ1=15°−26° and θ2=58.6° for residual-nucleus momenta in the range K B=0–150 MeV/c. Either arm of the spectrometer was equipped with polarimeters based on proportional chambers. The data coming from this experiment are analyzed within the distorted-wave impulse approximation. It is shown that the polarization of recoil protons formed at angle θ2 in the interaction featuring a proton from the P shell of the 7Li nucleus can be described under the assumption of an effective intranuclear-proton polarization by using the single-particle shell-model wave function of the nucleus. Our data on the polarizations of the two protons from the reaction (p, 2p) on a 28Si nucleus also suggest the effective polarization of the protons in the D shell of the 28Si nucleus. It is found that, for high recoil-nucleus momenta of K B≥90 MeV/c, the effective polarization of the protons in the P shell of the 6Li nucleus—this polarization was discovered in studying the polarization of recoil protons in the reaction 6Li(p, 2p)5He—cannot be described within the shell model assuming LS coupling. As might have been expected, the polarization of recoil protons knocked out from the S shells of the 6Li and 7Li nuclei comply well with the predictions obtained in the impulse approximation with allowance for the depolarization effect alone.
REACTION WITH THE LI6 P-SHELL PROTON.
REACTION WITH THE LI6 P-SHELL PROTON.
REACTION WITH THE LI6 P-SHELL PROTON.
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