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COHERENT AND INCOHERENT NUCLEAR $pi$$sup 0$ PHOTOPRODUCTION

Journal Article · · Nuovo Cimento (Italy) Divided into Nuovo Cimento A and Nuovo Cimento B
OSTI ID:4825227
A simple treatment of neutral pion photoproduction in complex nuclei, using closure and neglecting nuclear absorption of the pi /sup 0/, is considered in the region of small momentum transfer. In addition to the usual incoherent process in a nucleus, the fact that the nucleon on which the pi /sup 0/ is produced does not change its charge gives rise to the possibility of a coherent addition of the production amplitude over the whole nucleus, provided the momentum transfer to the nucleon is not large compared to the inverse nuclear size. Because the spin independent part of the production ampli tude which is responsible for the coherent process, has a sin theta dependence ( theta is the angle between pion and photon), the coherent cross-section will vanish in the forward direction and will reach a maximum at an angle theta /sub m/ = (1.87) STAKr/sub 0/A/sup 1/2/!/sup -1/, where K is the photon momentum and r/sub 0/A/sup 1/2/ the charge radius of the nucleus. Due to the fact that the maximum does not occur at zero angle the ratios of the coherent cross-section at theta /sub m/ will behave as A/sup 1/2/ rather than Ai in different elements. An estimate of the incoherent process is included and it is shown that this cross section is less than the sum of A free nucleons for small momentum transfers and reaches the free nucleon value as the momentum transfer approaches the Fermi momentum. (auth)
Research Organization:
CERN, Geneva
NSA Number:
NSA-16-004706
OSTI ID:
4825227
Journal Information:
Nuovo Cimento (Italy) Divided into Nuovo Cimento A and Nuovo Cimento B, Journal Name: Nuovo Cimento (Italy) Divided into Nuovo Cimento A and Nuovo Cimento B Vol. Vol: (10), 21; ISSN NUCIA
Country of Publication:
Country unknown/Code not available
Language:
English

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Related Subjects

FERMI MODEL
INTERACTIONS
NUCLEONS
PHYSICS
PIONS