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U.S. DEPARTMENT OF COMMERCE, Rogers C. B. Morton, Secretary NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Issued September 1975

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For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 - Price $1.35

Stock Number 0303-01317


This monograph is based on lectures given by Dr. Wiesław Czyż at the University of Virginia during the spring semester of 1973. They cover selected topics in the field of high energy diffractive scattering and production processes. In addition to reviewing some well-known material there is much here that is new, both in content and form of presentation.

The material presented here is also part of a program of research and cooperation between the author and the National Bureau of Standards that was begun in 1967 when the author was a National Science Foundation Senior Foreign Scientist Fellow at The American University and a Guest Worker at the National Bureau of Standards. This cooperation was continued on an informal basis during his several visits to this country between 1968 and 1971. Since July 1972 this research has been the subject of a grant by the National Bureau of Standards to the Institute of Nuclear Physics, Krakow, Poland under the PL-480 program. The sponsorship of this program has greatly facilitated this effort which has produced a series of articles written jointly by the author and NBS staff. The result of this cooperation is reflected, however, not only in published papers, but in numerous unpublished notes as well as in these lectures themselves.

L. C. Maximon

Interactions of High Energy Particles with Nuclei*

W. Czyż**

Physics Department, University of Virginia, Charlottesville, Va. 22904

Elastic scattering and diffractive production processes induced in nuclear targets by high energy projectiles are discussed in this article. Special attention is paid to the interaction of high energy hadrons and photons. Interactions of high energy electrons and neutrinos are briefly mentioned. The common features of all these processes are emphasized throughout the article: The multiple scattering and shadowing processes inside of the target nuclei. An effort is made to develop a unified way of treating nuclear interactions of particles which are either hadrons or exhibit some hadronic components in such interactions.

This article is divided into seven sections: (1) Introduction, (2) Description of multiple scattering, (3) Elastic scattering of hadrons from nuclei, (4) Diffractive dissociation and diffractive excitation, (5) Diffractive production of hadrons in hadron-nucleon collisions, (6) Shadowing effects in inelastic electron-nucleus scattering, (7) Shadowing effects in neutrino reactions on nuclei.

Key words: Diffractive production; diffractive scattering; Glauber model; hadronic components of
photons; high energy scattering; multiple scattering; neutrino-nucleus interactions; shadowing

1. Introduction

Let us start by giving a few motives for discussing this subject:

(a) It is well known that nuclear targets are of considerable importance in high energy physics. Work on vector meson production on nuclei or 3′′ (5) coherent diffractive production (compare refs. [S3, S4, S5])1 is a good example of the role of nuclear targets. One observed also excitations of specific nuclear levels by high energy hadrons [1, 2]. This opens a possibility [2] of selecting diffractive productions with nuclear levels as their analyzers.

(b) The very high energy incident particles may also be important for physicists working on nuclear structure-although this point does not seem to be well established (presumably due to poor energy resolutions of high energy beams). Nevertheless, one still hopes to be able to learn something new, for example about short range nucleon correlation functions in target nuclei or about the presence of resonances in nuclear ground states [3, 4]—just to name two problems.

(c) One may also hope that, in the cases where the scattering from a nucleus cannot be reduced to the "elementary amplitudes" of the incident particle-target nucleon, some new physical situations may occur which stem from the complexity of the target. For example, in the case of π-nucleus scattering in the region of the (3, 3) resonance [5, 6] one may hope to learn something about the nature of the (3, 3) resonance because the exclusion principle (due to the many particle structure of the target) may distort the resonance and this distortion may depend on its internal structure.

In these notes the interactions of various different particles with nuclear targets are to be considered. Of course, we cannot cover all problems related to the interactions of hadrons, photons, and electrons (virtual photons) with nuclei-we must choose a certain point of view which unifies all these problems. The common denominator which we shall emphasize is the existence (or lack thereof) of "shadow effects" (which occur mostly for forward scattering and production processes). Such effects are very well established in the case of hadron scattering and photon-nucleus interactions; they are not well known in the case of neutrino reactions and very virtual photons (see refs. [S3, S5]).

* Based on a series of lectures given at Department of Physics, University of Virginia, during the spring semester 1973.

** Guest worker of the National Bureau of Standards, Washington, D.C., 1973–74. On leave from Institute of Nuclear Physics, Krakow, Poland.

1 Figures in brackets indicate the literature references at the end of this paper.

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