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.

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.

Radiation-Induced Movement of a Mercury Stain at Room Temperature and Liquid Helium Temperature

1982 ◽  
Vol 40 ◽  
pp. 376-377
Author(s):  
M. K. Lamvik ◽  
K. -H. Müller ◽  
K. Weiss
Keyword(s):  
Electron Microscope ◽  
Radiation Damage ◽  
Liquid Helium ◽  
Heavy Element ◽  
Room Temperature ◽  
Liquid Helium Temperature ◽  
Helium Temperature ◽  
Radiation Induced ◽  
Preliminary Study ◽  
Effects Of Radiation

Cryomicroscopy at liquid helium temperature has shown promise in protecting organic materials from the effects of radiation damage, and it might be expected that sensitive heavy-element stains would be similarly protected. We have made a preliminary study of a positively-stained protein specimen using the superconducting-objective electron microscope at Berlin. We have used the mercury stain TAMM, solubilized with penicillamine (TAMM-pen3), which is known to be radiation-sensitive, on tropomyosin paracrystals of the type made by Ohtsuki. Specimens were treated with 10μM TAMM-pen3 on the grid for times ranging from 15 min to 11 hr, then were washed with 1 ml water, blotted and dried. Staining time had little effect on our results. Here we are not studying the protein or stain specificity; our interest is in the movement of the stain, which we can clearly demonstrate.

scholarly journals Radiation damage in small-molecule crystallography: fact not fiction

IUCrJ ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 703-713 ◽  
Author(s):  
Jeppe Christensen ◽  
Peter N. Horton ◽  
Charles S. Bury ◽  
Joshua L. Dickerson ◽  
Helena Taberman ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Small Molecule ◽  
Absorbed Dose ◽  
Test Sample ◽  
General Mechanism ◽  
Dose Calculations ◽  
Diffraction Intensity ◽  
Radiation Induced ◽  
Effects Of Radiation

Traditionally small-molecule crystallographers have not usually observed or recognized significant radiation damage to their samples during diffraction experiments. However, the increased flux densities provided by third-generation synchrotrons have resulted in increasing numbers of observations of this phenomenon. The diversity of types of small-molecule systems means it is not yet possible to propose a general mechanism for their radiation-induced sample decay, however characterization of the effects will permit attempts to understand and mitigate it. Here, systematic experiments are reported on the effects that sample temperature and beam attenuation have on radiation damage progression, allowing qualitative and quantitative assessment of their impact on crystals of a small-molecule test sample. To allow inter-comparison of different measurements, radiation-damage metrics (diffraction-intensity decline, resolution fall-off, scaling B-factor increase) are plotted against the absorbed dose. For ease-of-dose calculations, the software developed for protein crystallography, RADDOSE-3D, has been modified for use in small-molecule crystallography. It is intended that these initial experiments will assist in establishing protocols for small-molecule crystallographers to optimize the diffraction signal from their samples prior to the onset of the deleterious effects of radiation damage.

An Investigation of Radiation Damage Induced by Hydroxyl and Oxygen Impurities In BaF2 Crystal

1994 ◽  
Vol 348 ◽  
Author(s):  
Chen Lingyan ◽  
Gu Mu ◽  
Wang Liming ◽  
Xiang Kaiiiua
Keyword(s):  
Optical Absorption ◽  
Radiation Damage ◽  
Radiation Effect ◽  
Local Density ◽  
Cluster Calculation ◽  
Γ Irradiation ◽  
Hartree Fock ◽  
Before And After ◽  
Baf2 Crystal ◽  
Oxygen Impurities

ABSTRACTThe radiation effect in hydrolyzed BaF2 was investigated through tile changes in their optical absorption and EPR spectra before and after γ-irradiation. The resulti demonstrated that hydroxyl and oxygen can be easily introduced into BaF2by means of a hydrolysis, the most likely modes are OH— ions substituting for fluorine and O2– ions substituting for fluorine associated with charge-compensating fluorine vacancies O2– — F+. Combining with the Hartree-Fock-Slater local-density discrete variational (HFS-Xα-DV) cluster calculation on some possible defects related to hydrogen and oxygen impurities, we propose that the radiation damage observed in hydrolyzedBaF2 can be explained in terms of OH— and O2– — F+ dissociation through a radiolysis.

Radiation Damage Mechanisms In Scintillator Materials: Applications to BaF2 and CeF3

1994 ◽  
Vol 348 ◽  
Author(s):  
L. E. Halliburton ◽  
G. J. Edwards
Keyword(s):  
Low Temperature ◽  
Optical Absorption ◽  
Radiation Damage ◽  
Room Temperature ◽  
Epr Spectrum ◽  
Absorption Bands ◽  
Paramagnetic Resonance ◽  
Damage Mechanisms ◽  
Temperature Damage ◽  
F Centers

ABSTRACTResults from recent radiation damage studies in high quality BaF2 and CeF3 crystals are presented. Optical absorption and electron paramagnetic resonance (EPR) techniques are used to identify specific radiation damage mechanisms. Specific attention is given to the role of oxygen and hydrogen in the room temperature damage of BaF2. Also, Mn2+ ions are shown to change valence state in BaF2during room temperature irradiation. Numerous optical absorption bands are created in CeF3 during irradiations at low temperature. These bands are associated with electron traps (either F centers or Ce2+ ions) and they thermal anneal below room temperature. An EPR spectrum, assigned to F centers, is observed in low-temperature irradiated CeF3.

The effect of rare-earth impurities on the oxidation resistance of chromium

1980 ◽  
Vol 295 (1413) ◽  
pp. 331-331 ◽  
Keyword(s):  
Rare Earth ◽  
Radiation Damage ◽  
Nuclear Reactions ◽  
Rutherford Back Scattering ◽  
Group Iii ◽  
Back Scattering ◽  
Before And After ◽  
Deuteron Bombardment ◽  
Effects Of Radiation ◽  
Rare Earth Impurities

A systematic study has been made of the effects of Group III and rare-earth impurities on the thermal oxidation of chromium. The elements were introduced by ion-implantation to depths of about 30 nm with doses in the range 5 x 10 14 to 5 x 10 16 ions cm -2 . A number of the samples were annealed after implantation, to eliminate effects arising from radiation damage, and were subsequently oxidized for 30 min in dry oxygen at 750 °C. Impurity distributions were determined both before and after oxidation by means of Rutherford back-scattering of a particles, to correlate oxidation effects with the migration of impurities. Comparison of the oxygen uptake for the variously implanted samples was made by using deuteron bombardment and the 16 O (d, p) 17 O and 16 O (d, p) 17 O* nuclear reactions. Impurity analysis was carried out also by using a Cameca ion microprobe analyser. Initial studies designed to eliminate the effects of radiation damage, involving the implantation of Cr+ ions over a range of doses and energies, indicated that annealing at 750 °C was necessary to overcome the effects of bombardment-induced damage.

Effects of Radiation Induced Defects on Laser-Induced Breakdown in SiO2

1985 ◽  
Vol 61 ◽  
Author(s):  
M. J. Soileau ◽  
Nastaran Mansour ◽  
Edesly Canto ◽  
D. L. Griscom
Keyword(s):  
Radiation Damage ◽  
Laser Pulses ◽  
Breakdown Threshold ◽  
Γ Radiation ◽  
Laser Induced Breakdown ◽  
Radiation Induced ◽  
Effects Of Radiation ◽  
Induced Defects

ABSTRACTThe effects of radiation damage on bulk laser-induced breakdown in Si02 were studied. Samples studied included Spectrasil A, B, and WF (water free). Measurements of laser-induced breakdown were conducted with 532 and 1064 nm laser pulses of approximately 30 nsec duration. Reductions of up to 50% in the laser-ind ced breakdown threshold were observed at 530 nm for samples exposed to 108 rads of γ-radiation.

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.

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.

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