We have investigated the above processes at the CERN Intersecting Storage Rings (ISR). Results show a marked change of the slope parameter b ( t , s ) = (d/d t ) ln (d σ /d t ) around − t ≈ 0.10 GeV 2 . The s − and t − dependence of b ( t , s ) have been observed over the interval 460 GeV 2 < s < 2900 GeV 2 and 0.02 GeV 2 < t < 0.40 GeV 2 .
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This work extends our previous investigations at the CERN Intersecting Storage Rings, with improved statistics at three different energies, wider angular range and a better control over systematic errors. Values for the (diffraction) shape parameter b are given.
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The measurements of the differential cross section of elastic p-p scattering in relative units were performed in the energy range of 12–70 GeV. The values of the slope parameter were obtained from this data. It was shown that the slope parameter of the differential p-p scattering is monotonously increasing when the proton energy rises in the range 12–70 GeV. We have obtained the slope Pomeranchuk's pole trajectory from this data: α′ p = 0.40 ± 0.09.
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In interactions of 800-GeV protons with emulsion nuclei, the multiplicity and rapidity distributions of charged secondary particles are studied. The existence of strong short-range correlations among the secondary particles is found. Evidence of independent emission of low-multiplicity clusters is presented.
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3 H̃e nuclei were observed in the negative beam, produced by 70 GeV protons on an Al target. Five 3 H̃e have been identified among 2.4 · 10 11 particles that passed through the apparatus. Scintillation and Čerenkov counters were used to measure the electrical charge and velocity of particles. The mass of 3 H̃e is found to be M 3 H ̃ e = (1.00 ± 0.03)3m p , the charge is z = (0.99 ± 0.03)2 e . The ratio of differential production cross sections of 3 H ̃ e (P = 20 GeV /c) and π − (P = 10 GeV/c ) equals 2 · 10 −11 . This corresponds to antihelium −3 production cross section d 2 σ 3 H ̃ e / d Ω d P = 2.0 · 10 −35 cm 2 / sr · GeV /c per Al nuclei and 2.2 · 10 −36 cm 2 sr · GeV/ c per nucleon.
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The absorption cross sections of antideuterons with the momentum P = 13.3 GeV/ c by Li, C, Al, Cu and Pb nuclei have been measured. Antiproton stripping of antideuterons has been registered and its cross section for C, Al and Cu has been defined. The binding energy of antideuteron is found to be ε d = 2.4 ± 0.6 MeV by measuring the angular distribution of antiprotons from stripping.
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We have begun a program to measure dielectron production in p-nucleus and nucleus-nucleus collisions at the LBL Bevalac. Results are presented for the reaction p+Be at 4.9 GeV. For the first time, direct dilepton production is observed below 10 GeV incident energy. The cross sections are discussed and compared to previous data at higher energies. The observation of a structure at a mass of about 275 MeV suggests that pion annihilation may be the dominant production mechanism in this mass range.
A IS TARGET ATOMIC MASS NUMBER.
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A search for stableH-dibaryon ofI=0,Y=0,JP=0+ was undertaken in negative pion-, neutron-,12C-nucleus- and proton-propane interactions at 4.0, 7.0, 50.4 and 10 GeV/c, respectively, using 55 cm and 2 m propane bubble chambers. This technique permite one to examine the whole range of possibleH-mass value. In the range ofMH>2MΛ=2231.2 MeV/c2 an enhancement ofMΛΛ=(2365.3±9.6) MeV/c2, ΓΛΛ=(47.2±15.1) MeV/c2 with production cross section σ=(24.2±7.0) μb per carbon nucleus was found. The mass rangeMΣ−p<MH<2MΛ was explored via the search for a weak decay modeH→Σ−+p. AV0-particle was found pointing to a two-prong interaction and satisfying the kinematics of the above two-body decay mode with a high confidence level. The possibility of imitation of the observed event by background processes was investigated for a series of two-step strong reactions and weak decays. We succeeded to show the significance of theH-production hypothesis on a deuteron-mass nuclear fluctuon via thepd→HpK+K0 reaction. The mass of the event treated as aH→Σ−+p weak decay appeared to be (2173.94±1.32) MeV/c2, its life-time being 0.668·10−10 s. Both are in agreement with predictions of the MIT Bag Model for the so-calledH-dihyperon. The formally determined production cross section of theH in proton-propane interactions at 10 GeV/c is estimated to be 40 nb. Perhaps, this event can be considered as a first evidence for a six-quark bound state-H-dihyperon. An independent way for the search for theH-particle, based on a specific conversion processHN→YYN, peculiar to its intranuclear strong interactions was proposed and tried. For this purpose all events with two Λ-hyperons and identified protons were tested for the hypothesesHp→ΛΛp at three fixed masses:MH=1880.00, 2173.94 MeV/c2 and the ΛΛ invariant mass for the event in question. The kinematics of this reaction fits successfully only one event and only atMH=2173.94 MeV/c2. It seems worthy of note that the final state ΛΛ invariant massMΛΛ=2344 MeV/c2 is rather close to the observed peak at 2365 MeV/c2. It is shown that the intranuclear conversion processes Ξ−p→ΛΛ and Ξ0n→ΛΛ fail to imitate the observed event. The ΛΛp invariant mass of this event equal to 3363 MeV/c2 is out of a 3568 MeV/c2 peak region of the ΛΛp invariant mass spectrum observed earlier. TheH conversion cross section exceeds the production one. Thus, we consider this event as providing a new evidence for the stableH-dibaryon ofMH=(2173.94±1.32) MeV/c2.
Claime of DIBARYON(S=-2) with mass M=(2365.3+-9.6) MeV and width G=(47.2+-15.1) MeV.
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