Theoretical Calculation of coherent Laue-case conversion between X rays and ALPs for an X-ray LSW experiment

TL;DR

This paper presents a theoretical calculation of X-ray to ALP conversion in crystals via Laue diffraction, revealing longer interaction lengths and resonant conversion possibilities for keV-range ALPs, enhancing LSW experiment prospects.

Contribution

First theoretical analysis of Laue-case X-ray to ALP conversion in crystals using Darwin's diffraction theory, highlighting longer interaction lengths and resonant conditions.

Findings

Laue-case conversion has longer interaction length than Bragg case.

Resonant ALP conversion achievable by tuning incident X-ray angle.

ALPs up to 10 keV mass can be searched at synchrotron facilities.

Abstract

Single crystals have high atomic electric fields as much as 10^{11} V/m, which correspond to magnetic fields of \sim 10^3 T. These fields can be utilized to convert X rays into Axion Like Particles (ALPs) coherently similar to X-ray diffraction. In this paper, we perform the first theoretical calculation of the Laue-case conversion in crystals based on the Darwin dynamical theory of X-ray diffraction. The calculation shows that the Laue-case conversion has longer interaction length than the Bragg case, and that ALPs in the keV range can be resonantly converted by tuning an incident angle of X rays. ALPs with mass up to O(10 keV) can be searched by Light-Shining-through-a-Wall (LSW) experiments at synchrotron X-ray facilities.