Flat Trajectory Research Articles

Complex Regge Poles inπNBackward Scattering

The structure of the pole-cut combination in $\ensuremath{\pi}N$ backward scattering is represented by a complex ${N}_{\ensuremath{\alpha}}$ and ${\ensuremath{\Delta}}_{\ensuremath{\delta}}$ pair. For negative $u$, these are not complex conjugate but rather each pair splits into a steep (normal) and a flat trajectory. There are no MacDowell partners and each steep trajectory would produce the usual baryon spectrum at positive $u$ and the steep ${N}_{\ensuremath{\alpha}}$ is mainly responsible for the dips at $u\ensuremath{\approx}\ensuremath{-}0.2$ through wrong-signature nonsense zeros. The trajectories are generated by a $D$ function which has a fixed cut with squareroot singularity at the branch point. Excellent fits have been obtained for $\ensuremath{\pi}N$ elastic and charge-exchange differential cross sections in the backward direction.

Reactionpp→ppπ+π−at6.6 GeVc

A detailed analysis of 7514 $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{pp}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ events at $6.6 \frac{\mathrm{GeV}}{c}$ incident beam momentum is presented. Three types of analyses are presented which argue that a single-pion exchange process is responsible for the dominant peripheral ${\ensuremath{\Delta}}^{++}p{\ensuremath{\pi}}^{\ensuremath{-}}$ production. An angular-correlation analysis is presented in which it appears that the 1450-MeV $\ensuremath{\Delta}\ensuremath{\pi}$ Deck enhancement is not a pure ${J}^{P}={\frac{1}{2}}^{+}$ state. The demonstration that the absolute magnitude for this enhancement is accounted for by the pion-exchange process indicates that only one process (i.e., pion exchange with diffraction scattering at the ${\ensuremath{\pi}}^{\ensuremath{-}}p$ vertex) contributes to the final state, and that a second process need not be added to the pion exchange to account for the observed cross section. Some ad hoc dependence on the $\ensuremath{\Delta}\ensuremath{\pi}$ mass must be introduced for a precise fit to the shape of the $\ensuremath{\Delta}\ensuremath{\pi}$ mass spectrum, or equivalently to the $\ensuremath{\theta},\ensuremath{\varphi}$ angular distributions in the ${\ensuremath{\pi}}^{\ensuremath{-}}p$ c.m. system. The $S\ensuremath{\Delta}{\ensuremath{\pi}}^{2\ensuremath{\alpha}(t)}$ dependence of the Reggeized pion-exchange model of Berger is well known to accomplish this; however, the $\ensuremath{\alpha}(t)$ with unit slope required by this model is at variance with the apparently rather flat trajectory deduced from data on quasi-two-body pion-exchange-dominated reactions. It is suggested that a $\ensuremath{\Delta}\ensuremath{\pi}$ final-state-interaction model may be useful in understanding the reaction.

Regge Cuts and Iterative Procedures in Diffraction Scattering

Freund and O'Donovan's dynamical model for Regge cuts is extended to proton-proton diffraction scattering. The input Pomeranchukon is given a phenomenological representation corresponding to a flat trajectory. The question of which part of the total amplitude to identify with the input Pomeranchukon is examined in the context of a generating-function formalism. Consistency with the above-mentioned model and other physical requirements corresponds to restrictions on this generating function. We consider some new and some previously proposed iterative models for diffraction scattering, to wit: (1) a rescattering model (Van Hove), (2) a mixed rescattering-absorption model, (3) an eikonal (Chou-Yang, Frautschi-Margolis) model, and (4) a $K$-matrix model. Models (2)-(4) are consistent with our requirements and exhibit reasonable (and very similar) asymptotic differential cross sections. Possible modifications for nonasymptotic energies are discussed.

Promising equipment for underground excavators

1. Telescopic lever equipment, which enables the bucket to turn during its movement in the pile, shows promise because of its kinematics (scooping trajectory), output, and specific energy consumption. 2. The dynamic indices of these special types of equipment are of the same order as those of a straight shovel, except in the case of the short-arm type, which has greater “dynamicity” and load-nouniformity coefficients. 3. When the bucket is thrust into the pile at some height from the floor, scooping is materially imparied. In this case, the most favorable indices are those of the equipment with flat scooping trajectories. 4. For scooping up large fragments of rock, it is best to use a bucket with solid (not toothed) cutting edge. The use of this type (without change in the actual equipment) improves the output of an EP-1 excavator by 25–30%.

Computation of Flat Trajectories with High Angles of Departure

Computation of Flat Trajectories with High Angles of Departure

Computation of Flat Trajectories with High Angles of Departure

Computation of Flat Trajectories with High Angles of Departure

MEDICOMILITARY CONSIDERATIONS OF THE MODERN MILITARY BULLET

The modern military bullet is small of caliber, of comparatively light weight and is propelled at very high velocity by dense smokeless powder. It is sharp pointed and is cylindro-ogival in shape. The bullet consists, in most cases, of a central core of lead with an extremely hard jacket of nickel composition. The French bullet, however, is of solid copper. From the short, heavy, large-calibered bullet of lead, propelled at low velocity by black powder, the military bullet has changed, through many gradations, to a long, light-weight, small-calibered jacketed bullet, propelled at very high velocity, with flat trajectory, by smokeless powder and with a striking force of tremendous energy. It was originally believed that a bullet of this type, if it did not strike a vital part, would cause a simple perforating wound which would heal quickly and cleanly. Practical experience has shown that the modern military bullet commonly causes