Nucl.Phys.B

The results of the study of the π + p→K + ∑ + (1) and π + p→K + ∑ + (1385) (2) reactions at 12 GeV/ c are presented. The differential cross sections d σ /d t in| t min |<| t |<0.8 (GeV/ c ) 2 momentum transfer range are measured. The ∑ + polarisation for | t |<0.5 (GeV/ c ) 2 for reaction (1) is defined. Binary reactions (1) and (2) were selected by analyzing the missing mass spectra for the forward emitted fast K + meson. The total cross sections in the studied momentum transfer range are 20.2±2.4 μ b and 7.3±1.1 μ b for the reactions (1) and (2) respectively. The experimental results are compared with the predictions of the Regge models which take into account rescattering and secondary singularities.

Nucl.Phys.B

The paper presents results on measuring the polarization in the reaction π − p→ π 0 n at 40 GeV/ c in the 4-momentum transfer range 0<| t |⩽2 (GeV/ c ) 2 . The results based on the statistics of about 2.2 million recorded events made it possible to observe a noticeable value and complex structure in the polarization behaviour up to | t |⩽2 (GeV/ c ) 2 .

Lett. Nuovo Cim.

We measured4He(π±, π±p)3H and4He(π±π{±}2p2n) reactions at 120, 135 and 156 MeV. We found that the π+π- ratio is less than for free (π+p)/(π-p) elastic scattering.

Z. Phys. C

The ππ0 production in nuclear Coulomb field at threshold has been studied for the first time experimentally. The cross section of the reaction

Phys.Lett.B

Antiproton helium reaction cross section has been measured at 179.6 MeV with a self shunted streamer chamber in a magnetic field. Charged prong multiplicity, branching ratios and 3 He production probability are given. Comparison with p 2 H data is performed.

Nuovo Cim. A

The cross-sections for the reaction channels in the π+3He interaction at 145 MeV have been measured. The momentum distributions show evidence that the interaction in the π+pd channel is mainly due to the knock-out mechanism. Momentum and angular correlations in the absorption channel ppp show that the π+ absorption takes place mainly on np pairs.

Nucl.Instrum.Meth.A

A description is given of the detector system (self-shunted streamer chamber in a magnetic field) used in the PS-179 experiment at LEAR for studying antiproton interactions with light nuclei.

J. Phys. Colloq.

Abstract Parity nonconservation in neutron resonances of nonfissible nuclei is observed. The experimental results are in agreement with the parity nonconserving effects in thermal neutron cross sections and with the theoretical predictions.

Z. Phys. A

In the hydrogen bubble chamber study of the4Hep→dppn reaction at incident alpha 8.6 GeV/c momentum the structures in the two-proton effective mass distribution are observed at 2,035±15 MeV and 2,137±15 MeV. Possible nature of the effect is discussed.

J. Phys. G

Nuclear vertex functions and nuclear vertex constants have been obtained from analysis of the reaction 3He+p to p+p+d at 3He momenta of 2.5 and 5 GeV/c. The experimental data have been obtained by means of an 80 cm liquid hydrogen bubble chamber, exposed to 3He separated beams of 2.5 and 5 GeV/c momenta. The method of calculation of vertex functions and vertex constants is well founded. The effect of off-shell elastic scattering on the vertex functions and vertex constants has been investigated. The following values for the squares of the vertex constants have been obtained (Coulomb corrections were taken into account): 0.95+or-0.07+or-0.05 fm at 2.5 GeV/c and 0.99+or-0.07+or-0.05 fm at 5 GeV/c. The authors compare their vertex constants with available phenomenological results as well as with theoretical predictions calculated for different NN potentials.

J. Phys. G

The differential cross sections and the mean energy losses of fast protons in the reactions p+3H to pF+X and p+3He to pF+X are investigated using the ITEP 80 cm liquid-hydrogen bubble chamber exposed to beams of 2.5 GeV/c tritons (the kinetic energy of initial protons in the nuclear rest frame is Tp=0.318 GeV) and 5 GeV/c 3He nuclei (Tp=0.978 GeV). The experimental results are compared with predictions based on the sum rules for the differential cross sections and the mean energy losses which are valid in the Glauber-Sitenko multiple scattering theory when the completeness condition for the wavefunctions of the excited nuclear states and the locality of the nuclear potential are used. The data at 2.5 GeV/c are found to be in good agreement with the theory. The discrepancies between the Glauber sum-rule predictions and the data on 3He-p scattering at 5 GeV/c are explained by the effects of intermediate Delta -isobar production. Possible six-quark bag admixture in 3H or 3He nuclei is found to be not more than 5%.

Lett.Nuovo Cim.

A universal description of multiplicity distributions of negative particles is analysed for hA interactions at 40 GeV/c.

Z. Phys. C

Interactions of 40 GeV/c πp-,K− and\(\bar p\) on Li, C, S, Cu, CsI and Pb were studied with the RISK-streamer chamber spectrometer. We present multiplicities of negatively charged particles, as well as of protons, and the correlations between them. The normalized mean multiplicity of negative particles,R−, depends on\(\bar v\), the average number of inelastic collisions as\(R^ -= (0.73 \pm 0.04) + (0.34 \pm 0.02)\bar v\). The dependence of the normalized dispersion of negative particles,D−/, on the number of protons favours independent collision models and contradicts the coherent tube picture. The excess of fast positive particles behaves asA0.4 and shows, for the heavier nuclei, a clear correlation with identified protons.

Nucl.Instrum.Meth.A

A two-arm semiconductor spectrometer for the detection of secondary charged particles, such as p, d, t, 3 He, 4 He and of their correlations in the process of stopped pion absorption by nuclei is described. The spectrometer consists of two telescopes of Si-detectors with a sensitive surface of 800 mm 2 , two semiconductor detectors as monitors and the “live” target, a silicon surface barrier detector. The number of semiconductor detectors is 19. A technique for pion stop selection in thin targets is described. The problem of particle identification and of measurements of their energy with the help of a multicrystal semiconductor telescope is discussed. The technique provides an absolute normalization of spectra. The “alive” target helps to obtain more information on the process of pion absorption by Si-nuclei.

Yad. Fiz.

It has been shown that information on\(\bar p^4 He\) annihilation may impose limits on the possible amount of antimatter in the early Universe and other important cosmological parameters. We discuss which channels of\(\bar p^4 He\) annihilation must be measured and what restrictions on the parameters of GUT and SUSY models may be obtained from knowledge of the effective yields of different elements in\(\bar p^4 He\) annihilation.