Search

The recent reported evidence for the existence of the Λ6Li hypernucleus is questioned. No example of the (π−1H1H4He) decay mode of this hypernucleus was found in a sample of 7000 mesonically decaying hypernuclei.

The results of an experimental study of the binding energies of light hypernuclei are presented, based on a sample of 2008 uniquely identified π − mesonic decays. The problems of the calibration procedure and the selection criteria are discussed. Various aspects of the Λ -N interaction are reviewed in the light of these new results.

Results are presented concerning the experimental determination, with large statistics, of the branching ratios for the π- mesonic decay of the hypernuclei Λ3H and Λ4H. The spin assignments J(Λ3H) = 1 2 and J(Λ4H) = 0 are confirmed. © 1970., SCOPUS: ar.j, info:eu-repo/semantics/published

A 2.1 GeV/ c K − exposure in a heavy-liquid bubble chamber has been used to search for the final state Y ∗ (1327) → Λγ . No evidence was found for the existence of this state; an upper limit is placed on the cross-section of the reaction K − + p → Y ∗ (1327) + π + + π − + nπ o , n ⩾ 0 .

In a sample of approximately 11 000 hypernuclei obtained from K−-meson captures at rest in nuclear emulsion, eleven examples of the π+-mesonic decay of hypernuclei have been observed. From the ten which are attributed to the decay of4HeΛ, a value of (9±3)% is obtained forR, the ratio of π+ to π− mesonic decays for this hypernucleus. This result is larger than both that previously found experimentally and that predicted theoretically.

A 2.1 GeV/ c K − exposure in a heavy liquid bubble chamber has been used to search for the final states KΛΛ. An enhancement in the ΛΛ invariant mass spectrum at 2370 MeV/ c 2 is interpreted as a possible resonance produced in Ξ-nucleon interactions. An estimate of the cross-section for ΛΛ production in Ξ-nucleus reations is given.

Twenty examples of π+ mesonic decays of light hypernuclei have been found together with 7000 π− mesonic decays. The ratio R4 of π+ mesonic decays for the gL4 He hypernucleus has been computed from the results of this work and those of a previous experiment [1] and is found to lie between the values 5.4 ± 1.5%1.7% and 6.9 ± 1.8%2.1%. The π+ mesonic decays of other species of hypernuclei are briefly discussed.

In an experiment using a heavy liquid bubble chamber the Ξ hyperon lifetimes and α parameters were measured to be τΞo = (3.04 ± 0.230.26) × 10−10 sec, τΞ− = (1.73 ± 0.070.08) × 10−10 sec, αΞo = −0.84 ± 0.27 and αΞ− = −0.42 ± 0.11. These values agree with measurements which employed different techniques and are consistent with the predictions of the ΔI = 12 rule.

Results are presented on the\(B_\Lambda \) values of hypernuclei in the mass rangeA=3 toA=12 obtained from a sample of 595 uniquely identified π−-mesonic decays. The problems of what constitute adequate selection criteria for the unique identification of an event are discussed. The disagreement between the\(B_\Lambda \) values obtained from different decay modes of\({}^4B_\Lambda \) indicates a possible error in the range-energy relationship.

The results of a compilation of the binding energy values of light hypernuclei ( A ⩽ 16) obtained by the European K − Collaboration and the EFINS-North-western Collaboration are presented. The events were analysed by the same computer programme and uniform stringent selection criteria were applied.

Evidence for the existence of a particle-stable state of the 6 Λ He hypernucleus is presented.

In this study of hyperfragment production by K--meson absorptions at rest in emulsion nuclei, an attempt has been made to estimate the contribution of heavy spallation hyperfragments to the total observed number. In a sample of 24 640 K--meson captures, 1612 secondary events have been attributed to the production and subsequent decay of hyperfragments. From a study of the characteristics of both the production and decay disintegrations, it is concluded that about one half of the observed hyperfragments consists of λ0-hyperons trapped in the heavy spallation products of silver and bromine and these are almost entirely confined to the (0/3) μm range interval. The consequences of their presence aie discussed.