VUV spectroscopy of magnetically trapped atomic hydrogen

We discuss the experimental and theoretical aspects of absorption spectroscopy of cold atomic hydrogen gas in a magnetostatic trap using a pulsed narrow-band source (bandwidth 100 MHz) at the Lyman- wavelength (121.6 nm). A careful analysis of the measured absorption spectra enables us to determine non-destructively the temperature and the density of the trapped gas. The development of this diagnostic technique is important for future attempts to reach Bose-Einstein condensation in trapped atomic hydrogen.