Passive scalar intermittency in low temperature helium flows

We report new measurements of mixing of passive temperature field in a turb ulent Row. The use of low temperature helium gas allows us to span 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)> similar to r(xin) are shown to saturate to xi (x) similar or equal to 1 .45 +/- 0.1 for the highest orders, n similar to 10. This saturation is a s ignature of statistics dominated by frontlike structures, the cliffs. Stati stics of the cliffs' characteristics are performed, particularly their widt hs are shown to scale as the Kolmogorov length scale.