Observations on the Decay of Heavy Mesons in Photographic Emulsions

Resonance ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 1317-1345
Author(s):  
Naba K. Mondal ◽  
M. G. K. Menon ◽  
C. O’Ceallaigh
Keyword(s):  
Heavy Mesons ◽  
Photographic Emulsions

A search for nuclear disintegrations produced by slow negative heavy mesons

1954 ◽  
Vol 221 (1146) ◽  
pp. 394-405 ◽  
Keyword(s):  
Qualitative Analysis ◽  
Scattering Method ◽  
Mass Measurements ◽  
Heavy Mesons ◽  
Preliminary Results ◽  
Nuclear Interactions ◽  
Photographic Emulsions

This paper describes the preliminary results of a search for evidence of the nuclear interactions of negative heavy mesons. A qualitative analysis is given of the possible characteristics of their interactions and the appearance these might be expected to have in photographic emulsions. 37 ml. of emulsion, in which are recorded 10000 stars and 1200 slow π -mesons, have been completely examined. In the conditions of exposure, such a volume should contain six examples, with good geometry, of the decay of heavy mesons. Mass measurements have been carried out, by the range/scattering method, on 417 tracks of σ-mesons. In addition, 1800 σ-mesons, observed in 42 ml. of emulsion, have been examined. No disintegrations which can be attributed to heavy mesons have been found. The results suggest that some of the negative heavy mesons, on being brought to rest in photographic emulsions, behave in a manner qualitatively different from that of negative π -particles. Possible explanations for this result are suggested.

Observations on the decay of heavy mesons in photographic emulsions

1954 ◽  
Vol 221 (1146) ◽  
pp. 292-318 ◽  
Keyword(s):  
Charged Particle ◽  
Detailed Account ◽  
Heavy Mesons ◽  
Charged Mesons ◽  
Singly Charged ◽  
Photographic Emulsions

In 1951, two events were observed in photographic emulsions which appeared to correspond to the decay at rest of heavy charged mesons of mass ~ 1200 m e , the transmutations each involving the emission of a singly-charged particle (O’Ceallaigh 1951). The events were referred to as K 1 and K 2, respectively, and the decaying particles as K -mesons. Since these observations were made, eighteen similar examples have been found in this laboratory. They are referred to as K 3, K 4 . . . , K 20. The conditions of exposure of the plates in which they were recorded are given in table 2. Preliminary measurements, and conclusions following from them, have been reported at a number of conferences (Menon 1951; Powell 1952; Perkins 1952). This paper contains a detailed account of the measurements and their interpretation.

Production of heavy mesons by protons of energy between 2 and 3000 GeV

1954 ◽  
Vol 221 (1146) ◽  
pp. 351-366 ◽  
Keyword(s):  
Proper Time ◽  
Cosmic Ray ◽  
Primary Energy ◽  
Heavy Mesons ◽  
Secondary Particles ◽  
Primary Particles ◽  
Charged Mesons ◽  
The Masses ◽  
Photographic Emulsions ◽  
Primary Interaction

The masses of the secondary particles emitted from disintegrations produced by cosmic-ray protons of energy greater than 2 GeV have been determined by observations on the grain density and scattering of their tracks in photographic emulsions. It has thus been possible to determine the yield of the heavy charged mesons with mass between 900 and 1400 m e , as a function of the energy of the primary particles. Among 325 secondary particles which produce tracks with grain density between 1⋅07 and 2⋅0 times the minimum value, twenty heavy mesons have been identified. The statistical distribution in the measured values of their mass is consistent with a unique value of 1210±40 m e . The total observed proper time of flight of these particles is 2⋅9 x 10 -10 s; no example of decay 'in flight’ has yet been observed. The rate of production of these heavy mesons, referred to as K -particles, has been compared with the frequency with which heavy mesons are observed to decay at rest; the ratio is consistent with the estimated lifetime of the K -particles. In the disintegrations produced by primary particles of energy greater than ~ 20 GeV, approximately equal energy goes into production of π-and K -particles. The yield of K -particles at a primary energy of 2 to 3 GeV is estimated to be a few per cent per primary interaction. The results suggest th at not only π-mesons but also K -mesons are ‘heavy quanta’ associated with the nuclear field. If charged mesons of mass between 276 and 900 m e are created directly in showers, they occur with a frequency < 1 % of the π-particles.

The production of V -particles in low-energy interactions

1954 ◽  
Vol 221 (1146) ◽  
pp. 412-413 ◽  
Keyword(s):  
Total Energy ◽  
Cloud Chamber ◽  
Low Energy ◽  
Heavy Mesons ◽  
The Third ◽  
Chamber Experiment ◽  
Lead Plate ◽  
Secondary Interactions ◽  
Photographic Emulsions

The events described earlier showing the production of slow heavy mesons in photographic emulsions were interactions in which many shower particles were also produced. I should like to draw attention to three photographs which have been obtained in a cloud-chamber experiment carried out at the Jungfraujoch by a group from Manchester. These show the production of F-particles in interactions of very low multiplicity. In two of these events (Astbury, Chippindale, Millar, Newth, Page, Rytz & Sahiar 1952) slow-charged F-particles are produced in secondary interactions in a lead plate in the cloud chamber. The only other visible products of these interactions are one and two shower particles respectively. The third event is a star in the gas of the cloud chamber from which a neutral V -particle emerges. The total energy of the star is estimated as less than 1010 eV. This event is fully described by Astbury, Buchanan, James, Millar, Newth, Page, Rytz & Sahiar (1953).

Photographic Equidensitometry of High Voltage Electron Images of Thick Noncrystalline Materials

1972 ◽  
Vol 30 ◽  
pp. 594-595
Author(s):  
Keinosuke Kobayashi
Keyword(s):  
High Voltage ◽  
Linear Response ◽  
Thickness Distribution ◽  
Contour Map ◽  
Mass Thickness ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Homogeneous Particle ◽  
Photographic Emulsions ◽  
Logarithmic Relation

Equidensitometry as developed by E. Lau and W. Krug has been little used in the analysis of ordinary electron photomicrographs, yet its application to the high voltage electron images proves merits of this procedure. Proper sets (families) of equidensities as shown in the next page are able to reveal the contour map of mass thickness distribution in thick noncrystalline specimens. The change in density of the electron micrograph is directly related to the mass thickness of corresponding area in the specimen, because of the linear response of photographic emulsions to electrons and the logarithmic relation between electron opacity and mass thickness of amorphous object.This linearity is verified by equidensitometry of a spherical solid object as shown in Fig. 1a. The object is a large (1 μ) homogeneous particle of polystyrene. Fig. 1b is a composite print of three equidensities of the 1st order prepared from Fig. 1a.

Factors in Photographic Emulsions for Low Dose Electron Crystallography

1980 ◽  
Vol 38 ◽  
pp. 230-231
Author(s):  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
Radiation Damage ◽  
Low Dose ◽  
Damage Effect ◽  
Photographic Emulsion ◽  
Electron Crystallography ◽  
Electron Microscopic ◽  
X Ray ◽  
Signal Contrast ◽  
Diffraction Patterns ◽  
Photographic Emulsions

With the advances in preparing biological materials in a thin and highly ordered form, and in maintaining them hydrated under vacuum, electron crystallography has become an important tool for biological structure investigation at high resolution (1,2). However, the electron radiation damage would limit the capability of recording reflections with low intensities in an electron diffraction pattern. It has been demonstrated that the use of a low temperature stage can reduce the radiation damage effect and that one can expose the specimen with a higher dose in order to increase the signal contrast (3). A further improvement can be made by selecting a proper photographic emulsion. The primary factors in evaluating the suitability of photographic emulsion for recording low dose diffraction patterns are speed, fog level, electron response at low electron exposure, linearity, and usable range of exposure. We have compared these factors with three photographic emulsions including Kodak electron microscopic plate (EMP), Industrex AA x-ray film (AA x-ray) and Kodak nuclear track film (NTB3).

Disintegrations produced in the light elements of nuclear emulsions by 950 MeV protons

1956 ◽  
Vol 236 (1204) ◽  
pp. 104-111 ◽  
Keyword(s):  
Potential Barrier ◽  
Coulomb Barrier ◽  
Light Nucleus ◽  
Light Nuclei ◽  
Light Elements ◽  
Heavy Nuclei ◽  
Particle Track ◽  
Proton Track ◽  
Photographic Emulsions ◽  
Mev Protons

Ilford G 5 photographic emulsions have been exposed to 950 MeV protons from the Birmingham synchrotron, and 430 m of proton track searched for nuclear disintegrations. Disintegrations of carbon, nitrogen and oxygen were selected by the potential barrier criterion; the adequacy of this method, which depends on the presence of a short a-particle track indicating the low Coulomb barrier of a disintegrating light nucleus, is discussed. The characteristics of the disintegrations occurring in the light nuclei are described and compared with those for heavy nuclei; most of the observed differences can be explained as features of the complete break-up of a nucleus consisting of a small number of nucleons.

A study of the nuclear disintegrations produced by 950 MeV protons

1955 ◽  
Vol 231 (1186) ◽  
pp. 368-378 ◽  
Keyword(s):  
Simple Model ◽  
Excitation Energy ◽  
Residual Nucleus ◽  
Parent Nucleus ◽  
Heavy Nuclei ◽  
Substantial Fraction ◽  
Photographic Emulsions ◽  
Mev Protons

Nuclear disintegrations produced in the heavy nuclei of Ilford G 5 photographic emulsions by 950 MeV protons have been analyzed in detail. The characteristics of the disintegrations observed can be explained in terms of a simple model which assumes that a substantial fraction of the π mesons created is reabsorbed in the parent nucleus and that the energy of these mesons contributes mainly to the excitation energy of the residual nucleus.

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