Druck-Materie 20b.qxd - JUWEL - Forschungszentrum Jülich

4÷÷÷÷5K (see Fig. 8). Saturation curve of thermal resistance goes close to that of radicals. It
seems that radicals may be responsible for the effect absorbing phonons. Thermal
conductivity of ice at saturation is close to that of solid methane, only 50% higher. This
phenomenon can be useful for experimental study of radiation effects in ice.
Figure 8. Comparison of saturation of inverse thermal conductivity of ice value (left scale) and stored
energy (right scale).
7.3. Condition for spontaneous and thermally stimulated burps
Regularities which were perceived for condition of burps are as follow:
• a burp could always be induced by temperature rise of cooling helium if energy accumulated
in a sample exceeded 30-40 J/g (as low as for solid methane).
• In opposite to methane, for stimulated burps in ice no evident universal relation between
stored energy and temperature of ignition was found. Nevertheless, for each of eleven induced
burps, the same equation of line as for methane fits experimental data more or less
(see Fig. 9):
Q ≈≈≈≈ C⋅⋅⋅⋅ (Tcl - Tign) (6)
But now, Tcl is not identical for different temperature of irradiation and is equal approximately
to
Tcl ≈≈≈≈ 1.5 T irr + 6. (6’)
Factor C ≈7-8 J/g/K, being weakly dependent on T irr , is close to that of methane.
• No (or only small) dependence of a size of a sample on ignition condition was observed for
the range of effective sizes 15 -5 mm;
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