Micro-source development for XMASS experiment

XMASS is a multipurpose liquid-xenon detector that currently aims to directly detect dark matter. In this paper, we describe the fabrication and characterization of reference sources used for the energy calibration and position reconstruction of the present XMASS detector. Several gamma-ray sources were produced in the form of a sealed needle-source. A thin-wall tube with a diameter of approximately 0.2 mm was sealed at both ends, with the 241Am or 57Co source material contained inside. The active region of the source was observed to be 1–2 mm long, close to the tip of the needle. These sources were tested in the XMASS detector, and the results were compared with Monte-Carlo simulations.