  We report new measurements of turbulent mixing of temperature fluctuations in
a low temperature helium gas experiment, spanning a range of microscale
Reynolds number, $R_{\lambda}$, from 100 to 650. The exponents $\xi_{n}$ of the
temperature structure functions $<|\theta(x+r)-\theta(x)|^n > \sim r^{\xi_{n}}$
are shown to saturate to $\xi_{\infty} \simeq 1.45 \pm 0.1$ for the highest
orders, $n \sim 10$. This saturation is a signature of statistics dominated by
front-like structures, the cliffs. Statistics of the cliff characteristics are
performed, particularly their width are shown to scale as the Kolmogorov length
scale.
