Summary The masses of charged mesons, produced among the ‘shower’ particles in the nuclear interactions of protons of great energy have been determined by scattering and grain-density measurements. For energies greater than 50 Bev heavy mesons of mean mass ∼1300 me , provisionally identified as κ-mesons, are produced with a frequency comparable with that of the π-mesons. Evidence for the creation of such heavy mesons is also provided by an observed decrease in the ratio of neutral π-mesons to shower particles at very high energies. A method is described for measuring the lifetime of the neutral φ-meson, which takes advantage of the existence of an alternative mode of decay : φ0→γ+β++β− . It is shown that the proportion of φ-mesons which decay in this second mode is not greater than 4%. The preliminary observations suggest that the mean lifetime is about 10−14 see.

LXXII. Nuclear interactions of great energy.—Part I. Evidence for the creation of heavy mesons

In a set of 23,000 cloud-chamber photographs taken in a study of penetrating showers, 134 examples of the decay of neutral $V$-particles, and 18 of the decay of charged $V$-particles, were observed. An analysis of the 152 examples leads to the following principal conclusions: (1) $V$-particles result from the impact of mesons and probably also of nucleons, upon nuclei. (2) $V$-particles are generally produced singly and not in pairs. (3) Two independent kinds of data, one based on measurements of angles and other purely spatial relationships, and the other based on measurements of momentum and specific ionization, lead to the conclusion that more than 80 percent of these neutral $V$-particles decayed by the production of a heavy positive and a light negative particle. The mass of the heavy positive particle in most instances was consistent with that of a proton, but in a few cases may have been somewhat less. The negative particle appeared most often to be a $\ensuremath{\pi}$-meson, although in a few cases a $\ensuremath{\mu}$-meson was indicated. In about 7 percent of the cases, the positive particle was light and had a mass consistent with that of a $\ensuremath{\pi}$- or $\ensuremath{\mu}$-meson. In these cases the mass of the negative particle was not well determined. So far, therefore, in these investigations, there is no direct evidence that a neutral $V$-particle decays into two $\ensuremath{\pi}$-mesons, or into a positive $\ensuremath{\pi}$-meson and a negatively charged proton, although a few cases may be so interpreted. (4) The data are consistent with the assumption of a two-body decay for a majority of the neutral $V$-particles, and therefore a rather extensive analysis is given based upon this assumption. (5) The energy release, or $Q$-value, of the decay of neutral $V$-particles was computed, on the assumption of a two-body decay, for those cases in which the production of a heavy positive particle was clearly indicated, and where momentum measurements were possible. On the assumption of a decay into a proton and a ${\ensuremath{\pi}}^{\ensuremath{-}}$ meson, the $Q$-values obtained ranged from 10 Mev to about 100 Mev. The great majority of cases however, may be described in terms of discrete $Q$-values at 35\ifmmode\pm\else\textpm\fi{}3 Mev, and 75\ifmmode\pm\else\textpm\fi{}5 Mev, although, of course, the data are consistent with distributions about these values. For the same set of cases, if the positive particle is assumed to be as light even as $1250{m}_{e}$, and/or the negative particle is assumed to be a $\ensuremath{\mu}$-meson, the distribution of $Q$-values is not greatly changed, and the apparent necessity for at least two different $Q$-values remains. In those few cases mentioned in (3) above, in which the positive particle was light, and in which the mass of the negative particle was undetermined, the energy release, computed on the basis of a two-body decay, depends upon the assumed identity of the decay products, and is about 100-130 Mev for the assumption that two $\ensuremath{\pi}$-mesons are produced, about 50-80 Mev for a positive $\ensuremath{\pi}$-meson and a negative $\ensuremath{\tau}$-meson, and about 30-80 Mev for a positive $\ensuremath{\pi}$-meson and a negative proton. (6) The rest mean lifetime of ${V}^{0}$ particles, which appear to yield protons and ${\ensuremath{\pi}}^{\ensuremath{-}}$-mesons as decay products, was found to be 1.6\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ sec for 26 cases having $Q$-values greater than 50 Mev, and 2.9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ sec for 48 cases having $Q$-values less than 50 Mev, on the assumption of a two-body decay. In view of the rather poor statistics, the above two lifetimes are consistent with a single value, and lead to an average of 2.5\ifmmode\pm\else\textpm\fi{}0.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ sec. The above lifetimes are not appreciably changed if a multibody decay of the neutral $V$-particle is assumed. (7) The data are not adequate to distinguish conclusively between a two-body and a multi-body decay, and, therefore, a discussion is also given in terms of a variety of possible decay schemes of the neutral $V$-particle.

The Decay of V 0 Particles

In this paper we present some results on charged heavy mesons. They were obtained with an experimental arrangement consisting essentially of two large cloud-chambers placed one above the other. The top chamber had a magnetic field while the bottom chamber was of the multiplate type. The contents of the different sections of the paper can be summarized as follows: 1. The double cloud-chamber method is compared with other more conventional methods. 2. The apparatus is briefly described. 3. The behaviour in the multiplate chamber of the charged secondaries of V±-decays occurring in the top chamber is disscussed. π-mesons have been identified through their nuclear interactions. The presence of μ-mesons is also strongly suggested by:a) the long mean free path of the secondaries andb) one direct mass measurement. 4. S and slow V±-events observed in the multiplate chamber are discussed. It is shown that one should distinguish between two groups of decays: One with secondaries of range smaller than 20 g cm−2 of Pb, the other with larger range secondaries. Although the first group can be due to τ-mesons, the second group cannot be so explained, at least not phenomenologically. 5. The results of mass measurements—from range and momentum—on the primaries of the second group of events are presented. The measurements agree with a unique value of (914±20) me; which appears to be different from the τ-mass. 6. We show that some, and probably most, of the secondaries of this second group of events are μ-mesons. This conclusion is based on the dynamics of the decay and results from the measured mass of the primary particle and the observed ranges of the secondaries. The observation of one large angle scattering indicates, however, that τ-mesons may also be present among the secondaries.

Étude des mésons K chargés, au moyen de deux chambres de Wilson superposées

This article surveys our empirical knowledge of the production processes, the nuclear interactions and the decay processes of K particles and hyperons, as this appeared at the close of 1956, and interprets these phenomena within the framework of the charge-independent classification scheme proposed by Gell-Mann and by Nishijima for these `strange particles'. The assignment of a `strangeness' quantum number to each strongly interacting particle is a deep-lying aspect of this scheme, and the main qualitative features of the empirical data allow a direct interpretation in terms of a law of conservation of strangeness through all strong interactions. Where appropriate, more detailed analyses of the phenomena are made on the assumption that charge independence holds for these strong interactions. The evidence on decay processes for K particles and hyperons is discussed in some detail. These processes violate the strangeness conservation law and also involve changes in the total isotopic spin for those cases where this quantity is relevant for the final particles. The success of Gell-Mann's ?T = ? rule in accounting for certain aspects of the decay data is considered for each of the latter cases; this rule is given a simple origin in Schwinger's model for strange particle decay processes, which is discussed briefly. The implications of symmetry between particle and antiparticle, as pointed out by Gell-Mann and Pais for the neutral K particles and their decay modes, is also discussed in some detail, together with an account of the experimental data on long-lived K? particles and anomalous K? decay modes. Indications in the data which bear on the spin and parity values for K particles and hyperons are stressed, especially for the decay modes associated with ? and ? particles. Although it is shown that the products of ? and ? decay necessarily differ in spin or in parity, a great similarity has been found concerning all other properties of the ? and ? particles, and the proposals which have been made to account for this situation are surveyed. For the ?? particle, observations on bound ?? hypernuclei provide much information relevant to the ??-nucleon interaction and the ?? spin and parity, and this is also discussed in some detail. A section is devoted to discussion of `anomalous events' for which no interpretation is known in terms of the interactions of the well-established particles. These events and the possibility that heavier unstable particles or perhaps resonance states may exist have an obvious importance, of special relevance for attempts to construct a theoretical foundation leading naturally to the Gell-Mann-Nishijima scheme. A brief discussion of the preliminary attempts to establish such a foundation is given. An appendix has been added in proof to discuss the recent observations on the failure of parity conservation and of charge conjugation invariance in certain weak decay processes, and the effects which a failure of these symmetry properties also for strange particle decays would have on the arguments made and the conclusions reached in this survey.

K Mesons and Hyperons their strong and weak interactions

A method is described in which the measurement of scattering of tracks at the end of their range is carried out on sets of cells of varying length, chosen so that the second difference of the sagitta remains constant. This permits the measurements to be made always at the optimum cell length and eliminates the inconveniences and inaccuracies of the methods in which the track is broken into several sections for measurement. The mass values of a series of K and J-particles have been determined, together with those of a group of protons which serves as calibration.

https://link.springer.com/content/pdf/10.1007%2FBF02820378.pdf

Determination of the mass of slow particles by the constant sagitta method

Summary Observations by the photographic method are described which establish the existence of heavy charged mesons, of mass about 1200me , which decay with the emission of a single charged particle. In one case, it is shown that the secondary charged particle is a μ-meson of energy 5·9 MeV. In another, it is a particle of charge |e| and of energy about 200 MeV. If the two particles are of the same type with similar modes of decay, then the charged secondary particle must be accompanied by at least two neutral particles. The question whether the κ-particles are identical with the τ-mesons which decay into three charged particles, is discussed.

CIV. Masses and modes of decay of heavy mesons.—Part I. κ-particles

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

C. O'Ceallaigh

Author Tools

Chat about Author

Papers

CIV. Masses and modes of decay of heavy mesons.—Part I. κ-particles