Measurement of the Sequential $3\alpha$ Process in the Photodissociation of $^{12}\mathrm{C}$

TL;DR

This study measures the cross sections of the sequential 3-alpha process in the photodissociation of carbon-12, confirming the mechanism's role in radiotherapy dosimetry through experimental data and theoretical modeling.

Contribution

It provides the first detailed experimental measurement of the sequential 3-alpha process in carbon-12 photodissociation and compares it with advanced theoretical calculations.

Findings

Sequential breakup kinematics confirmed

Theoretical calculations match experimental data

Process involves electromagnetic coupling to specific Be states

Abstract

The cross sections for the $^{12}\mathrm{C}(\gamma,\alpha)^{8}\mathrm{Be}\rightarrow 3\alpha$ reaction have been successfully measured using exclusive coincidence between three $\alpha$ particles, minimizing Compton background. Sequential breakup kinematics are evident, and the cross sections are presented as locally averaged histogram values. Theoretical \textsc{Fresco} CDCC-CRC calculations reproduce the experimental data, showing that the process involves electromagnetic coupling to both $^{8}\mathrm{Be}^{0^+}$ and $^{8}\mathrm{Be}^{2^+}$ states. This study confirms that the $^{12}\mathrm{C}(\gamma,\alpha)^{8}\mathrm{Be}\rightarrow 3\alpha$ reaction proceeds via a sequential mechanism, crucial for understanding its significance in radiotherapy dosimetry.