Interactions In Nuclear Emulsion Research Articles

Inelastic π −-nucleon interactions at 6.8 GeV in the bubble chamber

Bubble chamber pictures taken from the 24 1 propane bubble chamber of the Joint Institute for Nuclear Research (Dubna) exposed to negative pions of (6.8±0.6) GeV/ c momentum were scanned for inelastic pion-nucleon interactions. A total of 171 inelastic π −-nucleon events has been found. The distributions of momenta, angles and transverse momenta are given. The results are compared with those of inelastic pion-nucleon interactions in nuclear emulsions. It is found that about 20% of the interactions identified in the propane bubble chamber are actually events which in nuclear emulsion would not show up as pion-nucleon collisions. From an investigation of the accidental and systematic errors in the momentum determination it is concluded that distortions in the bubble chamber and on the photographic film cannot be neglected if high momenta are measured.

A comparison of pion and nucleon interactions in nuclear emulsions between 10 11 and 10 13 eV

Using data obtained from a 10 1 emulsion stack by the Sydney group and a 22 1 stack by the Chicago group it is shown that at energies around 1000 GeV: a) the average number of shower particles in secondary jets (mainly produced by pions) is about half that in jets produced by protons, b) the spread of multiplicities in pion-nucleon encounters at a given energy is small, c) the spread of multiplicities in proton produced jets is considerable and in good agreement with the predictions of tunnel theory assuming a geometric interaction cross section for protons and d) the average number of heavy prongs in secondary jets (mostly produced by pions) decreases with increasing energy for about 15 at 6 GeV to about 3 at 5000 GeV.

Verification at 27 GeV of a formula for the determination of the primary energy of jets

Proton interactions in nuclear emulsions at 27 GeV have been analysed in order to verify at this energy the validity of the formula lgγc=〈lg|ctgθ|〉. Good agreement between expected and experimental values has been found for interactions withNh⩽4 andns⩾4. The correction to be introduced under the hypothesis of a pion spectrum due to statistical theory is discussed, as well as the dispersion of the value of logγc obtained.

Hypernuclei produced by K − interactions in nuclear emulsions (II) general characteristics and non-mesic decays

60 possible hypernuclei produced in 1104 K − interactions at rest and 415 K − interactions in flight, were analysed. The hypernucleus charge distribution was determined and the non-mesic to π − mesic ratio was given as a function of the hyperfragment charge. The stimulated decay was discussed. The hypernucleus formation probability was estimated.

Hypernuclei produced by K − interactions in nuclear emulsions (I) mesic decays

2 and 9 hypernuclei decaying according to the π − mesic mode were found in examining 415 K − interactions in flight and 1104 K − absorptions at rest, respectively. 9 of these hypernuclei were uniquely identified while for the remaining 2 there are more possible interpretations.

The analysis of 4.5 BeV negative pion interactions in nuclear emulsion

Abstract Two hundred nuclear interactions produced in Ilford G5 nuclear emulsion by 4.5 Bev π- mesons have been analysed. The transverse momentum of those secondary shower particles identified as pions has an average value over all angles of 290±50 MeV/C. The mean multiplicity of shower particles from the interactions is 2.0 ± 0.1 and is independent of the number of heavily ionizing prongs Nh . About 90 % of the shower particles were estimated to be pions. The angular distribution in the C-system is anisotropic with a mean value for |cos θ*verbar; of 048 ± 0.03. Assuming that secondary pions are emitted symmetrically backwards and forwards from a single collision system, the observed angular distribution of shower particles has been used to determine the effective mass of the collision partner. It is found to be 1.40+0.47 −0.27 proton mass units. If the total distribution is divided into groups with respect to Nh , it is found that events having Nh ≤7 yield a value of 0.77+0.36 −0.19 proton mass Units whi...

Observations of k−-meson interactions in nuclear emulsion

Abstract 23.6 metres of K−-meson track in nuclear emulsion have yielded unbiased samples of 815 absorptions at rest and 106 in flight. The corresponding interaction mean free path is 21.5+2.3 −1.9 cm for K−-meaons of energy below 90 Mev. Observations are reported on the disintegration stars themselves and on the charged hyperons produced. It is in particular noted that the angular correlation between hyperon and pion in two-pronged stars is closely that expected for a system without any nuclear interaction in the final state. It is shown that this and other aspects of the situation are most simply explained if the K−-meson is absorbed in the tenuous outer surface of the nucleus from a high Bohr orbit according to the model of Jones, and is not absorbed uniformly throughout the nuclear volume as is usually assumed. This surface absorption model allows of a strong hyperon-nucleon interaction such as appears to be indicated by a variety of other evidence and which would be inconsistent with the volume absorption model.

About high energy interactions in nuclear emulsions

Thirty-six plates of the 1-stack, which was exposed in the Po Valley expedition, were scanned for photon-electron cascades to find interactions of the highest energy. The plates were also area scanned for jets of lower energy. Measurements were made of the angular distribution of relativistic tracks. The energy of the colliding nucleons was determined for every jet. The resuits are analyzed. (M.H.R.)

Fast Meson Interactions in Nuclear Emulsions. I.π−Mesons

${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons produced in the Berkeley cyclotron are collimated and monochromatized to 35\ifmmode\pm\else\textpm\fi{}2 Mev by a toothed channel in the magnetic field of the cyclotron. Tracks of these mesons obtained in Ilford G5 emulsions are followed and studied for scatter, nuclear stars, and disappearances in flight. The energy distribution of the accepted mesons is critically examined and a low energy cutoff for the initial energy is established. 65 percent of the meson track is above 30 Mev in the region of observation, while the remaining 35 percent may drop to 20 Mev. The selection of the high energy particles and their identification by small angle scatter and grain density is discussed. Proton contamination is eliminated largely by small angle scatter. Electrons are ruled out by grain count.In 902 cm of track there are 5 disappearances and 26 scatters greater than 30\ifmmode^\circ\else\textdegree\fi{}; 4 of the scatters are detectably inelastic, with energy transfer greater than 18 Mev. The combined cross section for stars, disappearances, and inelastic scatters is equal to the cross section for elastic scatters. The measured value for total nuclear interaction is statistically compatible with the combined nuclear area for the responsible elements, oxygen, carbon, bromine, and silver.