HAL Id: jpa-00219267
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Submitted on 1 Jan 1979
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THE USE OF EFFECTIVE FEYNMAN DIAGRAMS FOR ATOMIC CROSS-SECTION CALCULATIONS
D. Salzmann, S. Eliezer
To cite this version:
D. Salzmann, S. Eliezer. THE USE OF EFFECTIVE FEYNMAN DIAGRAMS FOR ATOMIC CROSS-SECTION CALCULATIONS. Journal de Physique Colloques, 1979, 40 (C7), pp.C7-57-C7- 57. �10.1051/jphyscol:1979728�. �jpa-00219267�
JOURNAL DE PHYSIQUE CoZZoque C7, suppl6ment au n07, Tome 40, J u i l l e t 1979, page C7- 57
USE OF EFFECTIVE FEYNMAN DIAGRAMS FOR ATOMIC CROSSSECTION CALCULATIONS
D. Salzmann and S. Eliezer.
Soreq Nuclear Research Center, Yavne, I s r a e l .
A b s t r a c t . -
I n t h e developin? researcii of plasma diag- n o s t i c s i t i s n e c e s s a r y t o know t n e c r o s s - s e c t i o n s f o r Elany atomic p r o c e s s e s t o determine tile
temperature and p o p u l a t i o n d e n s i t i e s i n s t a t i o n a r y o r time-:dependent plasmas. Tiie main d i f f i c u l t y i n c a l c u l a t i n g atomic c r o s s s e c t i o n s i s due t o t h e wavefunctions of tile a t o n . We s u g g e s t a technique t o overcome t h i s d i f f i c u l t y by u s i n g " e f f e c t i v e Feynman diagrams". This technique i s i l l u s t r a t e d by o b t a i n i n g a simple r e l a t i o n between t h e cross- s e c t i o n s of e l e c t r o n impact e x c i t a t i o n
( e + i( + e + X ) and r e s o n a n t p l ~ o t o n a b s o r p t i o n
n m
(hv + Xn + Xm). The r e l a t i o n r e a d s ,
where a = 11137, mc' i s tile e l e c t r o n r e s t energy, U i s t h e L i n e t i c erlergy of tile inconling e l e c t r o n ,
Inn -- t h e e x c i t a t i o n energy, rmn - t h e n a t u r a l width and,
Y (u) = 1 1
-
- u12 2 + - - G Y . = 7 ImnImpressive agreement w i t h experiment i s found f o r t r a n s i t i o n s widely d i f f e r e n t i n n u c l e a r charge, degree of i o n i z a t i o n and atomic l e v e l s . An e x p l i c i t e x p r e s s i o n f o r t h e e l e c t r o n Gaunt f a c t o r i s given.
111e t e c h n i q u e developed i n t h i s paper i s a breakthrougn i n c a l c u l a t i n g t h e v a r i o u s e l e c t r o n - i o n and ion-$on s c a t t e r i n g c r o s s - s e c t i o n s and t h e corresponding r a t e - c o e f f i c i e n t s .
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979728