  In work [1] ("Temperature dependence of ultracold neutron loss rates"
E.Korobkina et al., PRB 70,035409) results of measurement of temperature
dependence of losses of ultracold neutrons (UCN) in a range from 4 K to 300 K
at UCN storage in a copper trap are presented. At interpretation of
experimental data it was artificially considered only the difference of losses
rate 1/tau(T)= 1/tau_exp(T)- 1/tau_exp(10K), (tau - UCN storage time in the
trap). It has been accepted for temperature dependence of losses which changes
from 0 to 3.3*10-4 per one collision of UCN with a trap surface. However, the
analysis of raw experimental data shows that in a trap at temperature 10 K
there is losses 1.0*10-3 per collision. They are considerably (in 3 times) more
than discussed temperature dependence and almost 10 times more than losses due
to capture cross section on copper. It is the most probable that these losses
are connected with leakage of UCN through a slit of trap shutter. Change of the
size of a slits on 25% at change of temperature from 300K to 10K can quite
explain discussed temperature dependence. Certainly, hydrogen is present on a
surface, but as it was shown at work [2] (V.P.Alfimenkov et al., JETP., Vol.
55, No. 2 25 Jan.1992) temperature dependence in 3 times lower, even on the
undegased surfaces than on the degassed and deuterated surface in work [1]. At
last, deuteration of a trap surface allows almost completely to suppress
temperature dependence connected with presence of hydrogen [2]. The conclusion
of work [1] is that hydrogen is localized on a surface in the form of a film,
instead of distribution in the surface substance. This conclusion contradicts
results of measurement of energy dependence of UCN losses in work [2]. More
detailed analysis of work [1] and works [2] is presented below.
