Borghini's Mechanism for Dynamic Polarization in Polarized Targets

TL;DR

This paper honors Michel Borghini's pioneering work on the mechanism of dynamic polarization in polarized targets, highlighting experimental evidence and its application in cancer therapy.

Contribution

It summarizes Borghini's proposed mechanism for dynamic polarization in amorphous organic materials doped with free radicals, supported by experimental evidence from CERN in the 1970s.

Findings

Experimental evidence supports Borghini's dynamic polarization mechanism.

High nuclear polarization achieved through spin-spin interaction cooling.

Application of Borghini's spin temperature theory in cancer therapy.

Abstract

This paper is a contribution to the memorial session for Michel Borghini at the Spin 2014 conference in Bejing, honoring his pivotal role for the development of polarized targets in high energy physics. Borghini proposed for the first time the correct mechanism for dynamic polarization in polarized targets using organic materials doped with free radicals. In these amorphous materials the spin levels are broadened by spin-spin interactions and g-factor anisotropy, which allows a high dynamic polarization of nuclei by cooling of the spin-spin interaction reservoir. In this contribution I summarize the experimental evidence for this mechanism. These pertinent experiments were done at CERN in the years 1971 - 1974, when I was a graduate student under the guidance of Michel Borghini. I finish by shortly describing how Borghini's spin temperature theory is now applied in cancer therapy.