# Bulletin of the American Physical Society

# 45th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics

## Volume 59, Number 8

## Monday–Friday, June 2–6, 2014; Madison, Wisconsin

### Session K1: Poster Session II (4:00pm - 6:00pm)

4:00 PM,
Wednesday, June 4, 2014

Room: Exhibit Hall

Abstract ID: BAPS.2014.DAMOP.K1.91

### Abstract: K1.00091 : Why criteria for impulse approximation in Compton scattering fail in relativistic regimes

Preview Abstract Abstract

#### Authors:

L.A. LaJohn

(Unversity of Pittsburgh)

R.H. Pratt

(Unversity of Pittsburgh)

$ of the initial bound state momentum distribution p. Comparing with S-matrix results, we find that at relativistic incident photon energies ($\omega_i$) and for high Z elements, one requires information beyond $

/q$ to predict the accuracy of relativistic IA (RIA) diferential cross sections. The IA expression is proportional to the product of a kinematic factor $X^{nr}$ and the symmetrical Compton profile J, where $X^{nr}=1+cos^2\theta$ ($\theta $ is the photon scattering angle). In the RIA case, $X^{nr}$, independent of p, is replaced by $X^{rel}(\omega ,\theta ,p)$ in the integrand which determines J. At nr energies there is virtually no RIA error in the position of the Compton peak maximum ($\omega_f^{pk}$) in the scattered photon energy ($\omega_f$), while RIA error in the peak magnitude can be characterized by $

/q$. This is because at low $\omega_i$, the kinematic effects described by S-matrix (also RIA) expressions behave like $X^{nr}$, while in relativistic regimes (high $\omega_i$ and Z), kinematic factors treated accurately by S-matrix but not RIA expressions become significant and do not factor out.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.DAMOP.K1.91

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