Nuclear reactions with polarized spin-1/2 beams

Hillhouse, G. C.(Gregory Campbell) (1990)

Thesis (M. Sc.) -- University of Stellenbosch, 1990.

Contents: Part 1. The polarization formalism for elastic proton scattering -- pt. 2. Relativistic effects on measured polarization observables.

Thesis

ENGLISH ABSTRACT: The first part of the thesis deals with the subject of polarization in nuclear reactions . The case where the incoming beam is polarized, is emphasized, and the theory is developed for the simple and illustrative cases of spin-t on spin-t scattering as well as spin-t on spin zero scattering. Finally, the polarization observables (or alternatively, the Wolfenstein-parameters) are introduced, their physical meanings and the ways in which they are measured, are discussed. In the second part we investigate the sensitivity of a complete set of spin-t on spin zero elastic scattering observables [ ~ , P, Q J to lelativistic and nonrelativistic predictions. The calculational approach is based on a simple relativistic extension of the first-order KMT optical potential within the context of a Dirac equation description. A formulation of this problem in terms of momentum space integral equations displaying an identifiable nonrelativistic sector is described and applied. The computer code WIZARD 1 is used in this respect and applied to the case of elastic scattering of polarized protons with energies of 135 MeV and 155 MeV on 24Mg, 2SSi and 325 targets. These results clearly demonstrate that the relativistic predictions are in far better agreement with the measured values than are the nonrelativistic results. We then propose the type of future measurements that can be made at the National Accelerator Centre, once the polarized-ion source has been installed. We also advise the implementations of relativistic calculations of the scattering observables.

AFRIKAANSE OPSOMMING: Die e.erste gedeelte van hierdie tesis handel oor die onderwerp van polarisasie in kern reaksies. Die geval waar die inkomende bundel gepolariseerd is, word beklemtoon, en die teorie word ontwikkel vir die eenvoudige en illustratiewe gevalle van spin-t op spin-t verstrooiing asook spin-t op spin zero verstrooiing. Daarna word die polarisasie waarneembares ( ook bekend as die Wolfenstein parameters) ingevoer en die fisiese betekenis en metings van hierdie parameters word bespreek. In die tweede gedeelte word 'n volledige stel waarneembares [ ~ , P, Q J , vir elastiese spin-t op spin zero verstrooiing, se sensitiwiteit tot relatiwistiese en nie-relatiwistiese berekeninge ondersoek. Die berekeninge word gebasseer op 'n eenvoudige relatiwistiese uitbreiding van die eerste orde KMT optiese potensiaal binne die raarnwerk .van Dirac se vergelyking. Die probleem word geformuleer in terme van momentum ruimte integraal vergelykings wat 'n mens in staat stel om die nie-relatiwistiese sektor van die probleem te identifiseer. Die rekenaar program \Vizard 1 word gebruik vir hierdie doel vir die geval van elastiese verstrooiing van 'n gepolariseerde bundels protone met energiee van 135 MeV en 155 MeV op 24Mg, 2BSi en 325 teikens. Die resultate toon duidelik aan · dat die relatiwistiese voorspellings in baie beter ooreenstemming is met die eksperimentele waardes as die ·rue-relatiwistiese geval. Ons stel voor watter tipe metings in die toekoms by die Nasionale Versneller Sentrum uitgevoer kan word, sodra die gepolariseerde ioonbron geinstalleer word. Verder word daar aanbeveel dat _relatiwitiese berekeninge van die verstrooiings waarneembares geimplementeer word.

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