Optical model studies of low energy (d,d) data show that deuteron-nucleus tensor potentials differ from theoretical model predictions. This suggests that measurement of additional observables, such as Polarization Transfer Coefficients (PTC), are needed to complement the existing data. Whether PTCs can clarify the experimental/theoretical ambiguity has been a matter of controversy. The first part of this thesis addresses this problem. We began by investigating whether the PTC, yields new information concerning the deuteron-nucleus tensor potential. We then examined the extent to which this coefficient can distinguish between the two types of tensor forces, Tr and Tp. We showed that Kyzz is strongly affected by tensor force effects, and that the origin of this sensitivity is the bi-linear combination of scattering amplitudes, Im(Q00Q*21). We also found that, for realistic optical mode parameters, T21 and particularly Kyzz discriminate between the effects of both tensor forces. In the second part of this thesis we study the Weinberg State Expansion model (WSE) for (d,p) reactions. The weakly bound structure of the deuteron suggests the relevance of 3-body effects in the dynamics of deuteron stripping. At intermediate energies, the DWBA provides a much less reliable description of particle transfer reactions. Although the adiabatic theory (ADIA) has provided improvements over the conventional DWBA, recent experimental data suggest that it needs to be refined. The WSE method, in which the dominant contributions from the 3-body channels are explicitly included, is a way to systematically improve ADIA which appears as the lowest order solution in the WSE theory. In implementing the WSE model, we found that as the Weinberg basis size N increases more c.m. n-p relative energies are simulated and readily included into the (d,p) calculations. We also showed that, when performing zero-range WSE calculations for 66Zn(d,p)67Zn (G.S.;5l2-;1 =3) at 25 and 88.2 MeV, the results for dsigma/dO and iT11 converge for N=35. Although 35 Weinberg states were used in constructing the new basis, the reaction calculation reduced to a three coupled channels problem. Our calculations are therefore more efficient than the CDCC methods. The WSE results for dsigma/dO and iT11 were also compared against those of equivalent ADIA and Quasi-ADiabatic (QAD) methods. Our findings reveal that: a) the WSE model provides significant corrections to ADIA's predictions and as such constitutes an elegant mathematical justification of ADIA's ideas; b) the WSE results are overall in good agreement with those obtained using QAD.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:280512 |
| Date | January 1991 |
| Creators | Laid, Abdallah |
| Publisher | University of Surrey |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://epubs.surrey.ac.uk/842772/ |
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