  We report on the X-ray spectral properties of 10 short bursts from SGR1900+14
observed with the Narrow Field Instruments onboard BeppoSAX in the hours
following the intermediate flare of 2001 April 18. Burst durations are
typically shorter than 1 s, and often show significant temporal structure on
time scales as short as $\sim$10 ms. Burst spectra from the MECS and PDS
instruments were fit across an energy range from 1.5 to above 100 keV. We fit
several spectral models and assumed Nh values smaller than 5$\times 10^{22}$
cm$^{-2}$, as derived from observations in the persistent emission. Our results
show that the widely used optically thin thermal bremsstrahlung law provides
acceptable spectral fits for energies higher than 15 keV, but severely
overestimated the flux at lower energies. Similar behavior had been observed
several years ago in short bursts from SGR 1806-20, suggesting that the
rollover of the spectrum at low energies is a universal property of this class
of sources. Alternative spectral models - such as two blackbodies or a cut-off
power law - provide significantly better fits to the broad band spectral data,
and show that all the ten bursts have spectra consistent with the same spectral
shape.
