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.

A Cluster Calculation of B and P Impurities in Amorphous Silicon

1990 ◽  
Vol 209 ◽  
Author(s):  
L. Enrique Sansores ◽  
R.M. Valladares ◽  
J.A. Cogordan ◽  
A.A. Valladares
Keyword(s):  
Solid State ◽  
Density Of States ◽  
Nearest Neighbor ◽  
Local Density ◽  
Cluster Calculation ◽  
Local Density Of States ◽  
Ionic Component ◽  
Pure Silicon ◽  
Hartree Fock ◽  
Covalent Nature

ABSTRACTThe local density of states and charge density contours of clusters of the type ISi20H28, where I can be Si, B or P, was calculated using the well-known pseudopotential SCF Hartree-Fock Method (and the HONDO Program). It is found that the covalent nature of the bonding in pure silicon gets altered and gives rise to an ionic component when B and P are substituted in the center of the cluster. Also, the local density of states in the neighborhood of a Si atom, nearest neighbor to the center of the cluster, show a splitting of the p-states at the top of the valence band in pure silicon when B is substituted, and a new p-state appears in the band gap when P is sustituted. These results are analyzed in the light of the local changes and its relevance to the solid state properties.

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.

Photolytic and thermal annealing of radical anions gamma-irradiated monocarboxylic acids

1979 ◽  
Vol 44 (12) ◽  
pp. 3632-3643 ◽  
Author(s):  
Karel Mach ◽  
Igor Janovský ◽  
Karel Vacek
Keyword(s):  
Thermal Annealing ◽  
Pivalic Acid ◽  
Esr Spectra ◽  
Paramagnetic Species ◽  
Radical Anions ◽  
Γ Irradiation ◽  
Before And After ◽  
Optical Bleaching ◽  
The Difference ◽  
Gamma Irradiated

Total yields of paramagnetic species, their optical bleaching and thermal annealing in acetic, propionic, a-butyric, isobutyric, and pivalic acid γ-irradiated at 77 K were followed by ESR spectroscopy. Radical anions, always found after irradiation, disappear during optical bleaching without formation of any paramagnetic product. During thermal annealing they are converted almost quantitatively into the α-radicals of the respective acid, with the exception of pivalic acid. Amounts of radical anions were estimated from the difference of integrated ESR spectra taken before and after optical bleaching. The results show that approximately equal amounts of the reduction and oxidation paramagnetic products of the γ-irradiation can be detected.

Preliminary Study on the Anti-radiation Effect of Jen-Sheng-Yang-Yung-Tang

1993 ◽  
Vol 21 (02) ◽  
pp. 187-195 ◽  
Author(s):  
Hsue-yin Hsu ◽  
Yau-hui Ho ◽  
Shi-Iong Lian ◽  
Chun-ching Lin
Keyword(s):  
Bone Marrow ◽  
Radiation Effect ◽  
Bone Marrow Cells ◽  
X Rays ◽  
Male Mice ◽  
X Ray ◽  
Colony Forming Units ◽  
Before And After ◽  
Preliminary Study ◽  
Different Doses

Six to seven week old male mice of ICR strain were exposed to different doses of x-rays to determine if Jen-Sheng-Yang-Yung-Tang could be a modifier in the elimination of radiation damage. Colony forming units of bone marrow cells in the spleen (CFUs) were measured before and after x-ray irradiation with intraperitoneal injection of 10 mg/20 g or 20 mg/20 g body weight of Jen-Sheng-Yang-Yung-Tang, once a day for seven consecutive days. The recovery of CFUs and hemocytes counts by 4 Gy irradiation with Jen-Sheng-Yang-Yung-Tang administration was faster for a concentration of 20 mg/20 g than 10 mg/20 g. The measurement of 10-day CFUs showed an increase of radiotolerance in the treatment of 20 mg/20 g administration before x-ray irradiation. The injection of Jen-Sheng-Yang-Yung-Tang accelerated the recovery of hemocyte counts in mice irradiated with 4 Gy x-ray; the effect was especially profound for leukocytes with 20 mg/20 g Jen-Sheng-Yang-Yung-Tang administration after irradiation.

scholarly journals Effect of Hartree–Fock pseudopotentials on local density functional theory calculations

2018 ◽  
Vol 20 (27) ◽  
pp. 18844-18849 ◽  
Author(s):  
Hengxin Tan ◽  
Yuanchang Li ◽  
S. B. Zhang ◽  
Wenhui Duan
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Calculations ◽  
Optimal Choice ◽  
Functional Theory ◽  
Hartree Fock ◽  
Local Density Functional Theory ◽  
Local Density Functional

Optimal choice of the element-specific pseudopotential improves the band gap.

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