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Title: Nuclear sizes from π+/- absorption
Author: Rajaratnam, Vijaya Henry
ISNI:       0000 0001 3505 8120
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1975
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Measurements of the absorption cross-section, sigma(pi+/-A) for pions (pi+/-) on nuclei (A=C,Ca,Ni,Sn,Pb) at the momenta ppit=(0.71, 0.84, 1.00; 1.36, 1.58; 2.00 Gev/c) were made with a secondary beam from the 7 Gev proton synchroton NIMROD at the Rutherford Lab. Pion Absorption should help to elucidate the nuclear surface. Rather it is the ratio sigma(pi-A)/sigma(pi+A) that is extremely sensitive to the relative distribution of neutrons and protons, but only at momenta where there is disparity in the affinity of the pion for a neutron or a proton (viz. 0.71, 0.84, 1.00 Gev/c). Where this disparity is negligible (1.36, 1.58 Gev/c) the ratio tends to unity bar Coulomb effects, and the results at these momenta check the optical model. The main input to the analysis are thus the pion-proton total cross-sections, those for the neutrons being obtained by charge independence; sigmat(pi+/-n)= sigmat(pi+/-p). These have to be Fermi averaged. In chapter I the need for reliable radial neutron distributions is stressed and this approach outlined with the help of semi-classical approximation. Experimental detail is fully covered in chapter II. Chapter III discusses results following closely ref. I, but concentrate on ratios, only remarking on the care required in work on absolute cross-sections. Prior to publication of ref. I, ref. II, a short letter presented the lead results but did not include any dependence on momentum transfer. Both references are to be found in the cover. The full analysis indicates that one commits an error of only one tenth of a fermi by taking the r.m.s. radius of the neutrons equal to the protons while the latter are in accord with lepton experiments. Smaller variation can be discerned within this error. Nearly two decades ago the first experiment of this type deduced that the square well radii for neutrons and protons in the heavy nucleus lead were equal.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available