  Radio spectroscopy at 323 MHz using the Arecibo Telescope and the VLA has
produced a tentative detection of the 21cm line of neutral hydrogen at
Z_abs=3.38716+-0.00007 in absorption against the radio continuum of the QSO
MG0201+113 (Z_em = 3.61). This redshift roughly agrees with one determined by
the Westerbork Synthesis Radio Telescope and reported earlier; however the
observations at different telescopes produce different results for width and
optical depth of the line.
  If the detection holds, it provides evidence for a high column density of
neutral gas that is confined to a dynamically cold layer with velocity
dispersion ~10 km/s. Although the interpretation is uncertain due to a lack of
detailed knowledge of the extended radio structure of the background quasar and
the relative quantities of neutral gas in the cold and turbulent components,
the observations specify high spin temperatures, T_s > 1000 K for both this
21cm line absorbing cloud and the turbulent component, which together have N_HI
~ 10^21.4 cm^-2. Results of optical spectroscopy require the additional
presence of metal-enriched clouds of still broader velocity dispersion than the
21cm line, creating a picture which is consistent with this system being a
young disk galaxy that is sufficiently evolved by z=3.4 to have collapsed to a
flattened system and produced a population of stars that have aged to pollute a
turbulent halo.
  The observations constrain the neutral gas mass of a possible 21cm line
emitter associated with the intervening absorber to be less than ~(Delta V/200
km/s) 10^13 Msolar for velocity widths Delta V (FWHM) in the range 200 to 1200
km/s (H_o=100 km/s/Mpc, Omega_o=1).
