1992    
1993    
1994    
1995    
1996    
1997    
1998    
1999    
2000    
2001    
2002    
2003    
2004    
2005    
2006    
2007    
2008    
2009    
2010    
2011    
2012    
2013    
2014    
2015    
2016    
Brandt, I. S., Wei, Z., Kirschner, J., Schumann, F. O.

Double electron emission from surfaces via low-energy positrons
Physical Review B 100, (7),pp 075139/1-6 (2019)
We have studied the electron pair emission process from surfaces due to the impact of a primary low-energy positron. The existence of this process implies a two-step scattering event. We find that the electron pair intensity is on the same scale as the positron-electron pair intensity. This suggests that a significant contribution of the pair intensity is actually due to the emission of three particles, of which two are detected. We also observe a strong material dependence of the coincidence intensity. Similarly to our previous studies with primary electron excitation or photon absorption, NiO is the material that displays the highest coincidence rates. We also note that the electron pair intensity scales with the single electron rate. This was also observed in electron pair emission with primary photons or electrons. This suggests that the coincidence intensity may provide a measure of the electron correlation strength.