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References
M. Danysz andJ. Pniewski:Phil. Mag.,44, 348 (1953).
R. G. Sachs:Phys. Rev. (in press). See alsoA. Pais:Phys. Rev.,86, 663 (1952). The same coupling constant is assumed, in the present discussion, for the Λ0-nucleon and nucleon-nucleon interactions; one may question, of course, whether this assumption is justified. Moreover, some admixture due to π-meson exchange can be expected.
F. Duimio:Nuovo Cimento,1, 688 (1955).
A. Bonetti, R. Levi Setti, M. Panetti, L. Scarsi andG. Tomasini:Nuovo Cimento,11, 210, 330 (1954).A. Debenedetti, C. M. Garelli, L. Tallone andM. Vigone:Nuovo Cimento,12, 466 (1954).M. Baldo, G. Belliboni, M. Ceccarelli, M. Grilli, B. Sechi, B. Vitale andG. T. Zorn:Nuovo Cimento,1, 1180 (1955). The binding energy of the Λ0 as obtained by using the data of each of these three groups, is 0.7±1 MeV, 0.3±4 MeV, and −0.2±1 MeV, respectively.H. Yagoda:Phys. Rev.,98, 153 (1955), has observed an event which he interprets as being the disintegration of a hypertriton in which the Λ0 is bound with 3.1±1 MeV. One should note, however, that the event of this reference may possibly be an example of a4HΛSuperscript>rather than a3HΛ. The mode of disintegration could be either (a)4HΛ→2H++p+n+π−+∼30.9±1 MeV, or (b)4HΛ →3H++p+π−+31.0±1 MeV. In both modes, the2H and3H are to be identified with the track which Yagoda designates byA. (The kinetic energy of the3H is about 2.01±0.06 MeV.) The two possible modes lead to a binding of the Λ0 in4HΛ of about − 0.3±1 MeV and 5.9±1 MeV, respectively.
An event, which may be the disintegration of either a3HeΛ or a4HeΛ, has been observed byFry, Schneps andSwami:The Disintegration of Hyperfragments (Univ. of Wis., preprint, Jan. 1955). Because the total binding energy found for3HeΛ (5.9±1 MeV) is almost twice that of3HΛ, the event is probably an example of a4HeΛ. If one assumes that the3nΛ is indeed stable, one can examine its possible modes of disintegration. For example, the mode, (a)3nΛ→2n++p+π−+Q a , is especially interesting because the charged secondaries are the same as those of the decay of the free Λ0. However, the apparentQ-value, i.e., theQ-value calculated from the observed kinetic energies of the p and π−, would not have a unique value for all events of this mode of disintegration of the3nΛ. One may ask whether mode (a) could possibly account for some of the low, anomalousQ-values which have been observed for the decay of the free Λ0. [See, for example,C. Castagnoli, M. W. Friedlander, M. Merlin andM. Teucher:Suppl. Nuovo Cimento,12, 460 (1954), especially p. 461]. For the mode, (b)3nΛ→t+π−+Q a , both secondary particles are charged and could be observed; in this case theQ-value plus the binding energy of the Λ0 would be 45.4 MeV.
Hill, Salant, Wigdoff, Osborne, Pevsner, Ritson, Crussard andWalker:Phys. Rev.,94, 797 (1954), whose data give 3.1 MeV.Naugle, Ney, Freier andCheston:Phys. Rev.,96, 1383 (1954), whose data give 2.7±0.9 MeV.Fry, Schneps andSwami: l. c., who find 3.9±1 MeV.J. Crussard andD. Morellet:Compt. Rend. Acad. Sci. (Paris),236, 64 (1953); this event is interpreted as the disintegration of either a4HeΛ or a1LiΛ. (In each case, theQ-value is slightly ambiguous because the kinetic energy of the recoil nucleus (3He or6Li) is not stated.) If the event is an example of a4HeΛ, the binding energy of the Λ0 (∼ 9±4 MeV) is somewhat higher than that of the other events quoted. See alsoBaldo et al.: l. c. The event of the latter reference is interpreted as the disintegration of either a4HeΛ or a6HeΛ, with the binding energy of the Λ0 equal to 1.7±1.2 or 1.5±1.2 MeV, respectively.B. Stiller, N. Seeman andM. M. Shapiro:Bull. A.P.S.,30, no. 5, 13 (1955), whose data give 1.9±2.9 MeV.W. F. Fry: private communication, who finds 0.9±0.5 MeV.
A preliminary estimate, based on a single event, reported inNature,175, 972 (1955) gives a 1.2±0.8 MeV for the binding energy of the Λ0 in4HΛ. See also reference (4).
See reference (7). No estimate of the binding energy of the Λ0 in the5HeΛ is given.
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Work performed in the Ames Laboratory of the U. S. Atomic Energy Commission.
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Jones, J.T., Knipp, J.K. Note on hyperfragments. Nuovo Cim 2, 857–859 (1955). https://doi.org/10.1007/BF02725049
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DOI: https://doi.org/10.1007/BF02725049