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 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.
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.
Neutral and charged two-pion production in p+d→ 3 He+2 π reactions has been studied at CELSIUS at a proton beam energy of 477 MeV. The total cross section for double pion production is 0.22±0.03 μ b. The ratio of the cross sections for the production of charged pion pairs with isospin T =1 and T =0 was determined to be σ ( π + π − ; T =1)/ σ ( π + π − ; T =0)=1.4±0.4.
(I=1, I=0) stands for isospin of PI+ PI- system.
The d( α , 6 Li ∗ 3.56 ) π 0 reaction has been studied at E c.m. =1.2 and 1.9 MeV above threshold with an alpha-particle beam incident on a deuterium cluster-jet target in CELSIUS. Complete differential cross sections were measured at both energies, integrated to σ =228±6+70 nb and 141±12+42 nb respectively. Observed large anisotropies are discussed in relation to the cluster structure of the 6 Li ∗ halo.
The excited LI6* level has E=3.56 mev (at the highest beam energy the second T=1 state in LI6 at 5.37 mev is possible to populate).
A search for double- Λ hypernuclei ( 12 ΛΛ Be) and H -dibaryons using the 12 C( K − , K + ) reaction was performed at the BNL-AGS using a high-intensity 1.8 GeV/ c K − beam. A missing-mass analysis below the end point of the quasi-free Ξ − production was used to investigate these S =−2 systems. The upper limit obtained for the forward-angle cross section of 12 ΛΛ Be production is 6 to 10 nb/sr. This is the first search for the direct production of double- Λ hypernuclei to reach the sensitivity required to observe the signal predicted by theoretical calculations. For the H -production cross section, we have obtained an upper limit in the range of a few nb/sr to 10 nb/sr for the H mass below 2100 MeV/ c 2 . This upper limit is the most sensitive H search result to date for a tightly bound H .
Upper limit is given.
The production of the H-dibaryon could occur via the (K-, K+) reaction on two protons in a nucleus: K- (PP) --> K+ H-dibaryon. Upper limit is given.
Total cross sections for the pp --> pp eta' reaction have been measured in the excess energy range from Q = 1.53 MeV to Q = 23.64 MeV. The experiment has been performed at the internal installation COSY-11 using a stochastically cooled proton beam of the COoler SYnchrotron COSY and a hydrogen cluster target. The determined energy dependence of the total cross section weakens the hypothesis of the S-wave repulsive interaction between the eta' meson and the proton. New data agree well with predictions based on the phase-space distribution modified by the proton-proton final-state-interaction (FSI) only.
Total cross sections w.r.t the excess energy in the CM system. Statistical errors only are given. As well as the 15 PCT overall systematic uncertainty there is an uncertainty on the energy of 0.44 MeV.
Structures of hadron-induced showers observed by the Pamir thick lead chambers are compared with simulations. The simulations are made for several models, VENUS, QGSJET, HDPM and the modified UA5 model, for hadron–nucleus interactions. A parameter Z , which is related to the inelasticity of hadron–Pb interactions, is defined and the Z -distribution of experimental data is compared with those of the simulations applying the same procedure of data processing to both sets of data. The Z -distribution for single-isolated hadrons is well reproduced by the models (VENUS, QGSJET and modified UA5) which give an average inelasticity 〈K h – Pb 〉=0.7 –0.8, whereas that for multi hadrons is close to the HDPM model which gives a smaller inelasticity of 〈K h – Pb 〉=0.5 –0.6. The difference of the characteristics between the two categories of hadron-induced showers is discussed.
Inelasticity of the first interaction, which defined by Kinel=1-Es/E0, where Es is the energy of the surviving particle and E0 is the incident hadron energy.
The p ̄ Ne annihilation cross section is measured for the first time in the momentum interval (53÷63) MeV/c. About 9000 pictures collected by the Streamer Chamber Collaboration (PS179) at LEAR-CERN have been scanned. Four events are found, corresponding to σ ann =2210±1105 mb. The result is compared to the set of measurements presently available in the region of low p̄ momentum.
No description provided.
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