1 - IAEA Nuclear Data Services

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XXo LABORATOIRE ïffl DE ORAAFF, UNIVERSITE DE LIEGE (Belgium)
Prof. L. VOTANT)
1 f\ 11
Differential scattering cross section of 0 (&,p) O
The Van de Graaff Laboratory has been studying the problem of the
detection of oxygen at the surface of metals, using protons from the
0 (ájp) O reaction.
For the study of surface layers containing low quantities of oxygen it
is necessary to know with a good accuracy the differential cross-section
1 f\
of the 0 (d,p) reaction for low E, values.
¥e have undertaken to study this reaction for deuteron energies lower
than 800 keV.
It is necessary to consider the equilibrium that establishes itself
between the residual oxygen in the chamber and the oxygen of the target.
This equilibrium is a function of residual pressure, partial pressures,
incoming beam intensity, (which modifies the surface temperature of the
target), the carbon deposits from vacuum pumping systems etc..
A systematic study of these factors has been undertaken, in order to
measure -rz and to determine the minimum amount of oxygen that can be
detected.
The accurate knowledge of -rr as a function of E will allow the oxygen
concentration to be measured as a function of the distance from the
target surface.
2. Long-range partióles from Po sources
The determination of the nature of the long range particles emitted
by Po sources has been done by multiple scattering measurements on their
tracks in nuclear emulsions. The result is consistent with the one
obtained previously by ionisation loss measurements and indicates that
these particles are protons. Their origin is still unexplained.