Temperature and number evolution of cold cesium atoms inside a wall-coated glass cell

TL;DR

This study investigates the temperature and atom number dynamics of cold cesium atoms in a wall-coated glass cell, revealing temperature fluctuations and elastic wall interactions relevant for precision laser cooling applications.

Contribution

It introduces a theoretical model incorporating elastic wall reflections and experimentally characterizes temperature and atom number evolution in wall-coated cells.

Findings

Temperature first decreases then increases during evolution.

Atom number declines slowly then rapidly.

Nonzero elastic reflection fraction p indicates partial elastic collisions.

Abstract

We report an experimental study on the temperature and number evolution of cold cesium atoms diffusively cooled inside a wall-coated glass cell by measuring the absorption profile of the 62S1/2 (F=4)-62P3/2 (F'=5) transition line with a weak probe laser in the evolution process. We found that the temperature of the cold atoms first gradually decreases from 16 mK to 9 mK, and then rapidly increases. The number of cold atoms first declines slowly from 2.1*10^9 to 3.7*10^8 and then falls drastically. A theoretical model for the number evolution is built and includes the instantaneous temperature of the cold atoms and a fraction p, which represents the part of cold cesium atoms elastically reflected by the coated cell wall. The theory is overall in good agreement with the experimental result and a nonzero value is obtained for the fraction p, which indicates that the cold cesium atoms are not all heated to the ambient temperature by a single collision with the coated cell wall. These results can provide helpful insight for precision measurements based on diffuse laser cooling.