Strong interaction experiments at the ZGS

The history of two related strong interaction experiments carried out at the Argonne ZGS accelerator in the mid 1960’s is described. These experiments involved the study of the production and decay distributions of π+p→ρ+N for forward production of ρ, and π+p→N∗+π for backward production of N∗. Special emphasis is given to the role played by Kent Terwilliger in conceiving these experiments and bringing them to a successful conclusion. A literature search is carried out to assess the impact of these experiments on the strong interaction physics of the period.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87538/2/125_1.pd

Momentum spectrum of hadronic secondaries in the multiperipheral model

Journal ArticleMotivated by a simplified multiperipheral model, we formulate a general qualitative description of the momentum spectrum of secondaries, resulting from a collision of two hadrons at high energies. Arguing from two fundamental multiperipheral concepts, (a) that transverse momenta are limited and (b) that distant particles on the multiperipheral chain are uncorrelated, we predict that at sufficiently high incident energies, the momentum spectrum of particle X in the reaction a ± b → X + anything, when presented in the variables pi and y = sinh-1[pll(pi2±mx2)½], develops a central plateau in the y dependence, which elongates and flattens to a value that is normalized b y the total cross section as the incident energy increases. Moreover, it is shown that the resultant particle density distribution is consistent with the hypothesis of limiting fragmentation. We contrast this description with the predictions of the two-fireball model, the isobar-pionization model, and the statistical thermodynamical model

Applications of group theory to fundamental particles and scattering

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Resonance production by energetic pions in hydrogen

An experiment has been described in which the interactions of positive pions in a hydrogen bubble chamber have been examined. Four lines of investigation have been followed. 1. The general behaviour of interactions in which four positively charged secondary particles are produced has been described. The cross-sections for these interactions and for different final states have been measured, and these have been found to be in reasonable agreement with these founding other experiments at different incident pion momentum. An examination has been made of the resonance production in reactions leading to the most common final states. Again, the results are in agreement with those from other experiments. 2. The quasi-two-body interaction :- π(^+) →N (→pπ(^+), pº(→π(^+)π(^-) π(^+) N (→pπ(^+), wº(→π(^+)π(^-)πº have been studied using the Gottfried-Jackson method of analysis. The spin density matrix elements obtained in this experiment are in agreement with the absorption model ion the first of those reactions, but in poor agreement for the second reaction, as has also been found in other experiments. The decay angular distribution of the B(^+) meson has been examined. He observed distribution is consistent with J(^P) assignment of 1(^+). 4. Different decay mode of the A (_2) meson have been observed, and a sample of two pronged events with at least one visible Vº decay was examined in order to observe the KK decay mode. The observed branching ratios are in agreement with those observed n other experiment. The recent suggestion that there may be more than one resonance with a mass in the region of the A(_2) mass has been investigated by examining the pn and the KK decay modes of the A(_2) separately. The observed characteristics of the two decay modes is consistent with the assumption that only one meson exists with mass in the region of 1.3 GeV/c(^2)

Particle production in strong interactions

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