McDonald, William Scott (1957) Photoproduction of neutral pions from hydrogen at forward angles from 240 to 480 MeV. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-07142004-161139
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Recoil protons from the process [...] have been detected by nuclear emulsions placed within a hydrogen gas target and used to measure the differential cross section for production of neutral pions. In this manner protons of energies as low as 5 Mev can be detected at laboratory angles corresponding to emission of a pion at center-of-momentum (C.M.) angles as low as 26[degrees]. This experiment thus supplements that of Oakley and Walker which is in the same range of photon energies (240-480 Mev), but is restricted to pion C.M. angles greater than about 70[degrees] due to higher minimum detectable proton energy. Common experimental points provide intercomparison of absolute values. Angular distributions are analyzed in the form [...] in the C.M. system. The combined Oakley-Walker and present data give the average value of the ratio [...] in the energy range from 260 to 450 Mev. The coefficient B, which gives the front-back asymmetry, passes through zero below the resonance energy of 320 Mev and is positive at higher energies. The theory of Chew and Low shows that the experimental angular distribution coefficients may be described rather well by magnetic dipole absorption leading to a state of angular momentum and isotopic spin 3/2 together with a small amount of S wave interference.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Physics, Mathematics and Astronomy|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1957|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||16 Jul 2004|
|Last Modified:||26 Dec 2012 02:55|
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