Experimental evidence of independence of nuclear de-channeling length on the particle charge sign

TL;DR

This study experimentally demonstrates that the nuclear dechanneling length is independent of particle charge sign for 120 GeV/c electrons and positrons in a silicon crystal, despite differences in channeling efficiency.

Contribution

It provides the first experimental evidence that nuclear dechanneling length is similar for electrons and positrons, regardless of their charge sign, in crystal channeling.

Findings

Nuclear dechanneling length is approximately 0.6-0.7 mm for both electrons and positrons.

Channeling efficiency differs significantly between electrons and positrons.

Dechanneling dynamics are similar for electrons and positrons despite charge differences.

Abstract

Under coherent interactions, particles undergo correlated collisions with the crystal lattice and their motion result in confinement in the fields of atomic planes, i.e. particle channeling. Other than coherently interacting with the lattice, particles also suffer incoherent interactions with individual nuclei and may leave their bounded motion, i.e., they de-channel. This latter is the main limiting factor for applications of coherent interactions in crystal-assisted particle steering. We experimentally investigated the nature of dechanneling of 120 GeV/c $e^{-}$ and $e^{+}$ in a bent silicon crystal at H4-SPS external line at CERN. We found out that while channeling efficiency differs significantly for $e^{-}$ ($2\pm2$ $\%$) and $e^{+}$ ($54\pm2$ $\%$), their nuclear dechanneling length is comparable, $(0.6\pm0.1)$ mm for $e^{-}$ and $(0.7\pm0.3)$ mm for $e^{+}$. The experimental proof of the equality of the nuclear dechanneling length for positrons and electrons is interpreted in terms of similar dynamics undergone by the channeled particles in the field of nuclei no matter of their charge.