$\text{High-P}^2_\bot$ spin dependent measurements

Abstract

The reason for studying the violent collisions of protons is to obtain information about the inner structure of the proton. To study the inner structure of the proton and to see what its constituents look like, one must observe large values of P _┴ which is the canonically conjugate variable to the impact parameter.

Now recall that, when you study proton-proton elastic scattering with an unpolarized beam, you can only measure one quantity, the spin average differential cross section. However, if either the beam or the target is polarized then you can measure one-spin quantities such as A, the analyzing power, which is sometimes incorrectly called the polarization. If both the beam and the target are polarized then you can measure two-spin quantities such as A_nn, the spin-spin correlation parameter. It is useful to now define the polarization:

$$P = \frac{N(\uparrow ) - N(\downarrow )}{N(\uparrow ) + N(\downarrow )}$$

This definition applies to both the beam polarization and the target polarization.

Supported by a research grant from the U.S. Department of Energy