The focusing of the HKU positron beam, and an extended design for incorporating secondary electron-positron annihilation lifetime spectroscopy

2006 ◽  
Author(s):  
Pui-ying, Rebecca Kwan
Keyword(s):  
Positron Annihilation ◽  
Secondary Electron ◽  
Positron Beam ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Electron Positron Annihilation ◽  
Electron Positron

scholarly journals PLEPS: Pulsed low energy positron system

2015 ◽  
Vol 1 ◽  
Author(s):  
Werner Egger
Keyword(s):  
Positron Annihilation ◽  
Depth Profiling ◽  
Positron Beam ◽  
Low Energy ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Variable Energy

PLEPS, operated by the Universität der Bundeswehr München, located at NEPOMUC, is a unique tool for depth profiling of defects with positron annihilation lifetime spectroscopy using a pulsed positron beam of variable energy.

Asymmetric Positron Interactions with Chiral Quartz Crystals?

2017 ◽  
Vol 373 ◽  
pp. 221-226 ◽  
Author(s):  
J. David van Horn ◽  
Fei Wu ◽  
Gerald Corsiglia ◽  
Yan Ching Jean
Keyword(s):  
Positron Annihilation ◽  
Depth Profile ◽  
Chiral Recognition ◽  
Shape Parameter ◽  
Positron Beam ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Doppler Broadening ◽  
Quartz Crystals ◽  
Positron Annihilation Lifetime ◽  
The Way

We have studied the interaction of the positron with chiral left-or right-handed quartz crystals. In Doppler-broadening experiments, using a mono-energetic positron beam there is a differential depth profile for positrons implanted in LH or RH z-cut quartz as identified by a shape parameter (S). Further, in bulk positron annihilation lifetime spectroscopy (PALS) experiments, the lifetime (τ 2) attributed to free annihilation of the positron interacting with the chiral lattice exhibits a larger value for the LH quartz, and the associated intensity (I2) is also significantly different—RH quartz is consistently 10% greater than the LH crystal. The τ3 lifetime and its intensity, I3, attributed to positronium interacting with defects in the quartz, also appears to exhibit differences between the enantiomeric sets of crystals. These observations may demonstrate chiral recognition using a positron annihilation technique, pave the way for a broad range of positron experiments, and may help inform hypotheses of chirality recognition, selection, or induction by beta radiation.

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