The p p and p n elastic differential cross sections have been extracted from the reaction p d→ p pn in which the deuteron breaks up. The incident antiproton momenta were 0.480, 0.735 and 0.940 GeV/ c , and the range of the momentum transfers was 0.04 < ∣ t ∣ < 0.7 (GeV/ c ) 2 . Both p p and p n differential cross sections are diffraction-like, with structure similar to the higher-momentum data.
No description provided.
No description provided.
No description provided.
The differential cross section for the reaction π − p→n π ° has been measured with high statistics at six incident beam momenta between 1.0 and 2.4 GeV/ c . The results are compared with predictions of recent phase shift analyses and forward dispersion relations.
No description provided.
FROM EXTRAPOLATING THE LEGENDRE POLYNOMIAL FITS.
THE LEGENDRE POLYNOMIAL FITS WERE CONSTRAINED IN THE EXTREME BACKWARD DIRECTION BY DATA AT THETA = 180 DEG FROM OTHER EXPERIMENTS.
Cross sections for γd and γn interactions and photoproduction of ϱ 0 and ω are studied at 4.3 GeV, using a linearly polarized photon beam in a deuterium bubble chamber. We find that σ T (γ n ) ⋍ σ T (γ p ) within about 5% and that the γn average charge multiplicity is lower than γp by 0.42±0.09. About 4000 ϱ 0 events and 70 coherent ω events are observed. We present total and differential cross sections for both xoherent and incoherent ϱ 0 production on deuterium, as well as decay angular distributions and density-matrix elements. We find that the t -channel isospin-one exchange amplitude in γ N → ϱ 0 N (e.g. A 2 exchange) is at most 5–13% of the dominant isoscalar amplituds. The ϱ 0 production mechanism is dominantly s -channel helicity-conserving (SHC) on both neutrons and protons. We find that relative to the SHC amplitudes, the single and double helicity-flip amplitudes at the γϱ 0 vertex are of the order of 10–15% for | t | > 0.25 GeV 2 , and have the same sign on both nucleons. This shows that helicity-flip is mainly due to isoscalar exchanges. The ratio of ω to ϱ 0 coherent forward cross sections is found to be 0.16±0.04. The natural-parity exchange part of γ N → ω N is strongly dominated by isoscalar exchanges, and the magnitude of the isovector-exchange is consistent with zero.
TOPOLOGICAL CROSS SECTIONS AND AVERAGE CHARGE MULTIPLICITIES GIVEN IN TABLE 1.
'PARAMETRIZATION'.
No description provided.
The two coherent reactions π+d → dπ+π+π− and π+d → → dπ+π+π+π0 are studied in the 2 m DBC at the incoming momentum of 11.7 GeV/c. The production cross-sections are measured:σ=(0.37±±0.06) mb andσ=(0.24±0.05) mb respectively. The two reactions are analysed in the different LPS configurations. The dσ/dt′ distribution for the two reactions displays the same exp[−At′] shape withA⋍37 (GeV/c)−2 in both cases, thus indicating that the differential cross-sections are dominated by the deuteron form factor. The coherent inclastic interaction contains the channel π+d → θ0π+d with a cross-sectionσ==(20±5) µb and a signal for the B+-meson of about 12 µb. The four-pion masses display structures below 2 GeV/c.
No description provided.
No description provided.
We have measured the total cross-section difference for pp scattering in initial spin states parallel to the beam direction at beam momenta of 1.17, 1.47, 1.69, 1.97 and 2.49 GeV/ c . This measurement was done in a standard transmission experiment. A striking energy dependence is observed with a maximum difference of −16.9 mb at P lab = 1.47 GeV/ c .
PRELIMINARY RESULTS.
PRELIMINARY RESULTS.
We have measured the difference between the pp total cross-sections for parallel and anti-parallel longitudinal spin states at beam momenta of 3 and 6 GeV/ c . These results, combined with our previous measurements, at lower momenta, are useful in clarifying a striking structure appearing at around 1.5 GeV/ c . We have also measured for the first time, the spin-spin correlation parameter C LL ( t ) in pp elastic scattering at 6 GeV/ c . We observe evidence for an exchange with A 1 -like quantum-numbers.
THE NEW DATA ON THE LONGITUDINAL CROSS SECTION DIFFERENCE, SIG(NAME=CLL) AT 3 AND 6 GEV ARE INCLUDED IN THE RECORD OF I. P. AUER ET AL., PL 67B, 113 (1977).
NOTE: HIGHER -T DATA ARE BEING ANALYSED. PUBLISHED GRAPH HAS LARGER ERRORS.
THESE NUMBERS APPEAR TO UPDATE THOSE REPORTED IN I. P. AUER ET AL., PRL 37, 1727 (76). NOTE: DATA MAY HAVE SMALLER ERROR BARS IN THE FINAL ANALYSIS.
We have studied the coherent dissociation of neutrons into pπ− systems, for a variety of nuclear targets, at incident momenta up to 300 GeV/c. Using a model incorporating both electromagnetic and hadronic production, we have extracted total cross sections for scattering of unstable pπ− systems on nucleons.
No description provided.
Measurements of inelastic electron scattering have been made in the range 2.2 < ν < 3.8 GeV and 0.1 < | Q 2 | < 0.3 (GeV/ c ) 2 , on a selection of nuclei ranging from hydrogen and deuterium to uranium, by measuring the scattered electron only. Detailed calculations have been made of the contribution of radiative tails to the measured yield. The results show a small ‘shadowing’ consistent with other electroproduction experiments, and also with photoproduction experiments in this ν range, but the shadowing decreases rapidly as | Q 2 | increases.
DEUTERIUM TO HYDROGEN CROSS SECTION RATIO (PER NUCLEON). FOR E(P=3) = 2.25 AND THETA = 8.5, THE RATIO IS 0.911 +- 0.037 (DSYS = 0.040).
No description provided.
No description provided.
None
CROSS-OVER IS AT -T = 0.17 +- 0.02 GEV**2. DIVIDE BY 20 TO GET D(SIG)/DT IN MB/GEV**2. CORRECTED FOR LOST EVENTS FOR -T < 0.12 GEV**2.
FROM QUADRATIC EXPONENTIAL FIT TO D(SIG)/DT. BOTH STATISTICAL AND SYSTEMATIC ERRORS INCLUDED IN VALUES.
We have measured the differential cross section d2σdΩdTπ and the polarization parameter P for the production of π+ and π− in various target nuclei (H1, H2, Be, C, O, Al, Ni, Cu, Mo, and Pb) by protons with a kinetic energy of 585 MeV, for production angles θπ=22.5°, 45°, 60°, 90°, and 135°, and for pion kinetic energies Tπ of 24, 35, 46, 88, 151, 192, and 254 MeV (all quantities in the laboratory system). Our data disagree strongly with recent data for 580-MeV protons. On the other hand, for pion energies up to 150 MeV, our cross sections differ little from those measured for a proton energy of 730 MeV. For nuclei with A>20, the total production cross sections σ(π+) and σ(π−) show the Z13 and N23 proportionality expected from theoretical arguments. There is evidence in our data of a shift of the π+ energy distributions compared to the π− distributions due to the effects of the Coulomb field of the nuclear protons on the emitted pions. NUCLEAR REACTIONS H1, H2, Be, C, O, Al, Ni, Cu, Mo, Pb p, π±, Tp=585 MeV; measured σ(Tπ, θπ) and asymmetry parameter P(Tπ, θπ).
No description provided.
No description provided.
No description provided.
Forum