Measurements of the photon induced production of $\Lambda$ in the $^2$H$({\gamma},{\Lambda})$X process at threshold energies

TL;DR

This study measures the production of Lambda particles induced by photons on deuterium near threshold energies, providing new experimental data on cross sections, momentum, and angular distributions to improve understanding of hyperon photoproduction.

Contribution

It presents the first detailed measurements of Lambda photoproduction cross sections, momentum spectra, and angular distributions at threshold energies using tagged photon beams.

Findings

Measured integrated cross sections for Lambda production.

Provided momentum spectra for specific photon energy ranges.

Determined angular distributions and polarization of Lambda particles.

Abstract

An experiment was carried out with the NKS2+ in 2010 at the Research Center for Electron Photon Science (ELPH), in which tagged photon beams in the range of 0.8 $\le$ $E_{\gamma}$ $\le$ 1.1 GeV were impinged on a liquid $^2$H target positioned at the center of the NKS2+. The produced $\Lambda$ was subsequently detected by the $p{\pi^{-}}$ decay channel. Integrated cross sections of the $^2$H$({\gamma},{\Lambda})$X in the angular region of 0.9 $\le$ $\cos{\theta}_{\Lambda}^{LAB}$ $\le$ 1.0 was derived and compared with preceding experimental results of the NKS2 collaboration. In addition, the momentum spectra for two photon energy regions were also procured. The ${\Lambda}$ angle dependent cross sections as a function of the scattering angle in the laboratory system was additionally deduced. We present the latest results on the excitation function of ${\Lambda}$ photoproduction, the momentum distributions, angular distributions, and polarization.