Chengyue Sun

Study on evolution of deep charge traps in polyimide irradiated by low-energy protons using photo-stimulated discharge technique

In this paper, low-energy proton irradiation effects on the evolution of deep charge traps in proton pre-irradiated polyimide are investigated using the photo-stimulated discharge (PSD) technique. The results indicate that in the PSD spectrum there appear three discharge bands with some sub-peaks in the wavelength range from 250 to 300 nm, 300 to 325 nm and 325 to 350 nm, respectively. After proton irradiation, the positions of the PSD bands show almost no change, while the integral intensity of the main PSD band (300–325 nm) decreases drastically from the original 175 pC in the pristine polyimide to the lowest one at about 10 pC in the irradiated sample, when 60 keV proton fluence is 1 × 1014 p cm−2. However, the intensity shows a certain recovery to about 50 pC as 60 keV proton fluence increases further to 1 × 1016 p cm−2. Further analyses indicate that the evolution of the PSD intensity is dependent on the displacement effect induced by proton irradiation. Structural analyses show that the degradation of carbonyl group in polyimide is the main reason for the decrease in PSD intensity due to proton pre-irradiation.

Radiation effects on optical and structural properties of GG17 Glasses induced by 170 keV electrons and protons

The effects of 170 keV electron and proton irradiation are investigated on the optical property and the structure of GG17-type borosilicate glasses for the purpose of assessing the suitability of this material for the rubidium lamp envelope, based on GEANT4 simulating calculation, using electron paramagnetic resonance and Fourier transform infrared spectra and optical-transmittance measurements. The Micro-mechanisms on damage of GG17 Glasses are clarified for electron and proton, respectively. For the electron with the energy of 170 keV, defect creation is due to ionization energy losses and the center is mainly boron oxygen hole center (BOHC) formed by one hole trapped on a bridge oxygen structure with [BO4]−. As a result the number of BOHCs grows as the electron fluence increases. However, for the proton with the energy of 170 keV, the creation of structural defects dominates by means of debonding as a result of an atom having been kicked off the structural chain (displacement effect). This leads to the...

Formation of E’γ Centers Under Electron Irradiation in Ultrapure Glass and Structural Relaxation

The processes of defect formation and evolution in ultrapure glass under 1 MeV electron irradiation were investigated by the measurement of electron paramagnetic resonance (EPR) spectra and optical absorbance. The results show that the 1 MeV electron irradiation of the ultrapure glass can induce the formation of E’γ centers, and the structure of the E’γ center transform from E’γ(1) center to E’γ(2) center with the increasing irradiation fluence, and this variation also affects the defect optical absorption property in the material. During the room temperature aging process, the defects anneal process induces the recovery of the optical property of the ultrapure glass. It is worth to note that the defect structure varied during the ageing process, namely, the E’γ(2) center transform to E’γ(1) center, and the variation of the defect structure induced the no synchronous property between the defect anneal and the optical absorption recovery.