Effect Of Low-energy Proton Irradiation Research Articles

Influence of low-energy proton irradiation on the effective lifetime in the space charge region of silicon n+-p junctions

The effect of low-energy proton irradiation on the pulse characteristics of silicon n+-p-p+ structures is analyzed. It is shown that irradiation with protons with an energy of 180 keV and a dose of 1015 cm−2 creates a region with an effective lifetime of 5.5·10−8 s in the space charge region of the n+-p junction. Such elements can be used to create high-speed photodiodes with an operating modulation frequency of 18 MHz.

Evolution of optical properties and molecular structure of PCBM films under proton irradiation

Low-energy proton irradiation effects on the optical properties and the molecular structure of phenyl-C61-butyric acid methyl ester (PCBM) are studied in this work. The PCBM films are irradiated by 100-keV proton beams with fluences of 5 × 1012 p/cm2, 5 × 1013 p/cm2, and 5 × 1014 p/cm2, respectively. The photoluminescence (PL) peaks of the post-irradiated PCBM films show a progressive decrease in the peak intensity as the proton fluences increase, which can be attributed to the deep defect levels induced by proton irradiation. Additionally, a slight blue-shift in the PL spectrum is also observed at a proton fluence of 5 × 1014 p/cm2. The underlying mechanism can be traced back to the lift of the lowest unoccupied molecular orbital (LUMO) level, which is caused by the attachment of methoxy radicals on ortho position of the phenyl ring in the post-irradiated PCBM structure. This work is of significance in understanding the radiation hardness and the damage mechanism of the PCBM film in radiation environments, which is essential before it is put into practical application in space.

The effect of simulated space radiation on the N-glycosylation of human immunoglobulin G1.

On a roundtrip to Mars, astronauts are expectedly exposed to an approximate amount of radiation that exceeds the lifetime limits on Earth. This elevated radiation dose is mainly due to Galactic Cosmic Rays and Solar Particle Events. Specific patterns of the N-glycosylation of human Igs have already been associated with various ailments such as autoimmune diseases, malignant transformation, chronic inflammation, and ageing. The focus of our work was to investigate the effect of low-energy proton irradiation on the IgG N-glycosylation profile with the goal if disease associated changes could be detected during space travel and not altered by space radiation. Two ionization sources were used during the experiments, a Van de Graaff generator for the irradiation of solidified hIgG samples in vacuum, and a Tandetron accelerator to irradiate hIgG samples in aqueous solution form. Structural carbohydrate analysis was accomplished by CE with laser induced fluorescent detection to determine the effects of simulated space radiation on N-glycosylation of hIgG1 samples. Our results revealed that even several thousand times higher radiation doses that of astronauts can suffer during long duration missions beyond the shielding environment of Low Earth Orbit, no changes were observed in hIgG1 N-glycosylation. Consequently, changes in N-linked carbohydrate profile of IgG1 can be used as molecular diagnostic tools in space.

Effect of low-energy proton irradiation on parameters of silicon structures with n-p junction

The dependences of the separation probability of the Frenkel pair on the temperature and the position of the Fermi level in the band gap cause the dependences of primary radiation defects concentration on the irradiation temperature and impurity concentration. This conclusion is confirmed by study results of electrophysical and optical properties of silicon n+-p-p+ structures, irradiated by the proton flux with the energy of 40 keV and the fluence of 1015 cm−2.

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.

High and low energy proton irradiation effects on AlGaN/GaN HFETs

AbstractAlGaN/GaN heterojunction field effect transistors (HFETs) have been irradiated with protons at 68 MeV and 2 MeV with fluences up to 1013 cm–2 in order to simulate operation in space. Hall effect measurements, dc characteristics and RF load pull measurements at 2 GHz do not reveal significant changes indicating the suitability of the transistors for reliable operation in space. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low-energy proton irradiation effects on GaAs/Ge solar cells

Abstract This paper reports the low-energy proton irradiation effects on GaAs/Ge solar cells for space use. The proton irradiation experiments were performed with a fluence of 1.2×10 13 cm −2 , energies ranging from 0.1 to 3.0 MeV. The results obtained demonstrate that the irradiation with a proton energy of 0.3 MeV gives rise to the most degradation rates of I sc , V oc and P max of the solar cells with no coverglass, which is related to the proton irradiation-induced vacancies near the pn junction in GaAs/Ge cells. The degradation rates of I sc , V oc and P max of the solar cells with coverglass increase as the proton energy increases due to the cascade ions induced by collision processes. It is found that the coverglass has an obvious protection effect against the irradiation with the proton energy below 0.5 MeV.