Scintillation Mechanism and Radiation Damage in CexLa1-xF3 Crystals

1994 ◽  
Vol 348 ◽  
Author(s):  
A. J. Wojtowicz ◽  
A. Lempicki ◽  
D. Wisniewski ◽  
C. Brecher ◽  
R. H. Bartram ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Radiation Damage ◽  
Light Output ◽  
Quenching Mechanism ◽  
Scintillation Light ◽  
Strong Function ◽  
Transfer Processes ◽  
Radiation Induced ◽  
Ce Content

ABSTRACTRecent spectroscopic and radiation damage experiments on a series of CexLa1-xF3 crystals suggest that the scintillation light output is limited by an unusual quenching mechanism, which also plays a major role in minimizing radiation-induced damage. The intensity of the radiation-induced absorptions is a strong function ofthe Ce content x, reaching a maximum for x = 0.03 and a minimum for x = 1. This peculiar dependence appears to be due to the influence of deep-lying Ce levels onboth scintillation mechanism and radiation damage. We suggest that various charge transfer processes can explain many aspects of the performance of CexLa1-xF3 scintillators.

Modelling charge transfer processes in C2+–tetrahydrofuran collision for ion-induced radiation damage in DNA building blocks

2017 ◽  
Vol 19 (30) ◽  
pp. 19722-19732 ◽  
Author(s):  
Ewa Erdmann ◽  
Marie-Christine Bacchus-Montabonel ◽  
Marta Łabuda
Keyword(s):  
Charge Transfer ◽  
Cancer Therapy ◽  
Radiation Damage ◽  
Building Blocks ◽  
Carbon Ions ◽  
Medical Treatments ◽  
Transfer Processes ◽  
Biological Interest

Investigations of the collision-induced processes involving carbon ions and molecules of biological interest, in particular DNA building blocks, are crucial to model the effect of radiation on cells to improve medical treatments for cancer therapy.

scholarly journals Light Output and Radiation Damage in A Lead Tungstate Crystal

1994 ◽  
Vol 348 ◽  
Author(s):  
J.A. Kierstead ◽  
S.P. Stoll ◽  
C.L. Woody
Keyword(s):  
Optical Absorption ◽  
Radiation Damage ◽  
Light Transmission ◽  
Light Output ◽  
Light Yield ◽  
Attenuation Length ◽  
Lead Tungstate ◽  
Before And After ◽  
Radiation Induced ◽  
Effects Of Radiation

ABSTRACTThe optical absorption, light output and effects of radiation damage have been studied ina 2.2 × 2.2 × 12.8 cm3 crystal of lead tungstate. The crystal exhibits a longitudinal attenuation length which varies from roughly 13 cm to 1.5 m over the region where the scintillation emission occurs (400-800 nm). The light yield produces approximately 10 photoelectrons per MeV on a photomultiplier tube with a bialkali photocathode. The scintillation and light transmission properties of the crystal were characterized before and after exposure to 1 Mrad of 60Co gamma rays. Significant radiation induced optical absorption was observed in this crystal, along with a considerable amount of phosphorescence after irradiation. Partial spontaneous recovery from the damage occurred at room temperature, and it was possible to induce additional recovery by optical bleaching.

Light Output and Radiation Damage in A YAIO3:Ce Crystal

1994 ◽  
Vol 348 ◽  
Author(s):  
J.A. Kierstead ◽  
S.P. Stoll ◽  
C.L. Woody
Keyword(s):  
Optical Absorption ◽  
Radiation Damage ◽  
Room Temperature ◽  
Spontaneous Recovery ◽  
Light Transmission ◽  
Light Output ◽  
Light Yield ◽  
Before And After ◽  
Radiation Induced ◽  
Effects Of Radiation

ABSTRACTThe optical absorption, light output and effects of radiation damage have been studied ina 2.1 × 2.1 × 2.1 cm3 crystal of YA103:Ce. The light yield produces approximately 2867 photoelectrons per MeV on a photomultiplier tube with abialkali photocathode. The scintillation and light transmission properties of the crystalwere characterized before and after exposure to 1 Mrad of 60 Co gamma rays. Significant radiation induced optical absorption was observed near the optical band edge ofthe crystal, along with an extremely intense phosphorescence after irradiation. Partial spontaneous recovery from the damage occurred at room temperature, and it was possible to induce additional recovery by optical bleaching.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Electro-active pi-Conjugated Oligomers and Polymers A Molecular Picture of Charge-Transfer Processes

2018 ◽  
Vol 15 (4) ◽  
pp. 388 ◽  
Author(s):  
D. Beljonne ◽  
J. Cornil ◽  
J. L. Brèdas ◽  
V. Coropceanu
Keyword(s):  
Charge Transfer ◽  
Semiconductor Devices ◽  
Conjugated Oligomers ◽  
Transfer Processes ◽  
Pi Conjugated ◽  
Information And Communication ◽  
Inorganic Semiconductor ◽  
Molecular Picture

<span>Inorganic semiconductor devices such as transistors have been instrumental in shaping the development of our society of information and communication. Recently, the electronics and photonics technologies have opened their materials base to organics, in particular p-conjugated oligomers and polymers. The goal with organics-based devices is not necessarily to attain or exceed the level of performance of inorganic semiconductor technologies...</span>

Fluorescence Quenching of Aminodiphenylamines with Chloromethanes

2002 ◽  
Vol 67 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Nachiappan Radha ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Ground State ◽  
Rate Constants ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
Charge Transfer Interaction ◽  
Electronically Excited ◽  
A Charge

The fluorescence quenching of 2-aminodiphenylamine (2ADPA), 4-aminodiphenylamine (4ADPA) and 4,4'-diaminodiphenylamine (DADPA) with tetrachloromethane, chloroform and dichloromethane have been studied in hexane, dioxane, acetonitrile and methanol as solvents. The quenching rate constants for the process have also been obtained by measuring the lifetimes of the fluorophores. The quenching was found to be dynamic in all cases. For 2ADPA and 4ADPA, the quenching rate constants of CCl4 and CHCl3 depend on the viscosity, whereas in the case of CH2Cl2, kq depends on polarity. The quenching rate constants for DADPA with CCl4 are viscosity-dependent but the quenching with CHCl3 and CH2Cl2 depends on the polarity of the solvents. From the results, the quenching mechanism is explained by the formation of a non-emissive complex involving a charge-transfer interaction between the electronically excited fluorophores and ground-state chloromethanes.

scholarly journals Molecular Hydrogen as a Potential Clinically Applicable Radioprotective Agent

2021 ◽  
Vol 22 (9) ◽  
pp. 4566
Author(s):  
Shin-ichi Hirano ◽  
Yusuke Ichikawa ◽  
Bunpei Sato ◽  
Haru Yamamoto ◽  
Yoshiyasu Takefuji ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Molecular Hydrogen ◽  
Regulation Of Gene Expression ◽  
Animal Experiments ◽  
Radiation Energy ◽  
Water Radiolysis ◽  
Low Dose Radiation ◽  
Oxidizing Power ◽  
Radiation Induced ◽  
Radioprotective Agent

Although ionizing radiation (radiation) is commonly used for medical diagnosis and cancer treatment, radiation-induced damages cannot be avoided. Such damages can be classified into direct and indirect damages, caused by the direct absorption of radiation energy into DNA and by free radicals, such as hydroxyl radicals (•OH), generated in the process of water radiolysis. More specifically, radiation damage concerns not only direct damages to DNA, but also secondary damages to non-DNA targets, because low-dose radiation damage is mainly caused by these indirect effects. Molecular hydrogen (H2) has the potential to be a radioprotective agent because it can selectively scavenge •OH, a reactive oxygen species with strong oxidizing power. Animal experiments and clinical trials have reported that H2 exhibits a highly safe radioprotective effect. This paper reviews previously reported radioprotective effects of H2 and discusses the mechanisms of H2, not only as an antioxidant, but also in intracellular responses including anti-inflammation, anti-apoptosis, and the regulation of gene expression. In doing so, we demonstrate the prospects of H2 as a novel and clinically applicable radioprotective agent.

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