TY - JOUR
T1 - Influence of surface conditions on thermal positron reemission spectra from W(100)
AU - Sudarshan, Sudarshan
AU - Wilkie, P.J.
AU - Samarin, Sergey
AU - Guagliardo, Paul
AU - Petrov, Vladimir
AU - Weiss, A.H.
AU - Williams, James
PY - 2013
Y1 - 2013
N2 - Our measurements trace the temporal dependence of positron reemission spectral features, namely, the reemission intensity, energy and angular distributions with post-cleaning time and oxygen exposure. The unwanted inelastic component in the reemission spectra can be kept at less than 6 % of the total reemitted positrons during long and continuous operation by simply ensuring the cleanliness of the sample with better vacuum level. Simultaneously the other optimized spectral features of the beam can be maintained except for the reemission spectral intensity which decreased with increasing time after cleaning. Even though oxygen at high temperature is used normally in the cleaning process of the tungsten moderators, exposure of the sample to oxygen at room temperature caused an exponential reduction in the reemission yield with exposure time. © 2013 Springer-Verlag Berlin Heidelberg.
AB - Our measurements trace the temporal dependence of positron reemission spectral features, namely, the reemission intensity, energy and angular distributions with post-cleaning time and oxygen exposure. The unwanted inelastic component in the reemission spectra can be kept at less than 6 % of the total reemitted positrons during long and continuous operation by simply ensuring the cleanliness of the sample with better vacuum level. Simultaneously the other optimized spectral features of the beam can be maintained except for the reemission spectral intensity which decreased with increasing time after cleaning. Even though oxygen at high temperature is used normally in the cleaning process of the tungsten moderators, exposure of the sample to oxygen at room temperature caused an exponential reduction in the reemission yield with exposure time. © 2013 Springer-Verlag Berlin Heidelberg.
U2 - 10.1007/s00339-013-7864-3
DO - 10.1007/s00339-013-7864-3
M3 - Article
VL - 113
SP - 633
EP - 639
JO - APPLIED PHYSICS A : MATERIALS SCIENCE & PROCESSING
JF - APPLIED PHYSICS A : MATERIALS SCIENCE & PROCESSING
SN - 0947-8396
IS - 3
ER -