Rapid Migration of Defects in Ion-Implanted Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
J. Lalita ◽  
P. Pellegrino ◽  
A. Hallén ◽  
B. G. Svensson ◽  
N. Keskitalo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Dose Rate ◽  
Long Range ◽  
Room Temperature ◽  
Rate Effect ◽  
High Dose ◽  
Range Migration ◽  
Mev Protons ◽  
Dose Rate Effect

ABSTRACTThe temperature dependence of the so-called reverse dose rate effect for generation of vacancy-type defects in silicon has been investigated using samples implanted with 1.3 MeV protons at temperatures between 70 and 300 K. The effect is found to involve a thermally controlled process which exhibits an activation energy of ∼0.065 eV, possibly associated with rapid migration of Si self-interstitials (I). Further, using a concept of dual Si ion-implants long range migration of I:s at room temperature has been studied. Annihilation of vacancy-type defects at a depth of ∼3 μm is obtained by injection of I:s from a shallow implant with sufficiently high dose.

High Dose Rate Effect of Focused-Ion-Beam Boron Implantation into Silicon

1984 ◽  
Vol 23 (Part 2, No. 6) ◽  
pp. L417-L420 ◽  
Author(s):  
Masao Tamura ◽  
Shoji Shukuri ◽  
Tohru Ishitani ◽  
Masakazu Ichikawa ◽  
Takahisa Doi
Keyword(s):  
Dose Rate ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Dose Rate ◽  
Rate Effect ◽  
High Dose ◽  
Boron Implantation ◽  
Dose Rate Effect

scholarly journals Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro

2017 ◽  
Vol 58 (6) ◽  
pp. 894-897 ◽  
Author(s):  
Nelly Babayan ◽  
Galina Hovhannisyan ◽  
Bagrat Grigoryan ◽  
Ruzanna Grigoryan ◽  
Natalia Sarkisyan ◽  
...  
Keyword(s):  
Dna Damage ◽  
Electron Beam ◽  
Dose Rate ◽  
Rate Effect ◽  
High Dose ◽  
Distribution Analysis ◽  
Beam Radiation ◽  
Dna Damages ◽  
Dna Damage And Repair ◽  
Dose Rate Effect

Abstract Laser-generated electron beams are distinguished from conventional accelerated particles by ultrashort beam pulses in the femtoseconds to picoseconds duration range, and their application may elucidate primary radiobiological effects. The aim of the present study was to determine the dose-rate effect of laser-generated ultrashort pulses of 4 MeV electron beam radiation on DNA damage and repair in human cells. The dose rate was increased via changing the pulse repetition frequency, without increasing the electron energy. The human chronic myeloid leukemia K-562 cell line was used to estimate the DNA damage and repair after irradiation, via the comet assay. A distribution analysis of the DNA damage was performed. The same mean level of initial DNA damages was observed at low (3.6 Gy/min) and high (36 Gy/min) dose-rate irradiation. In the case of low-dose-rate irradiation, the detected DNA damages were completely repairable, whereas the high-dose-rate irradiation demonstrated a lower level of reparability. The distribution analysis of initial DNA damages after high-dose-rate irradiation revealed a shift towards higher amounts of damage and a broadening in distribution. Thus, increasing the dose rate via changing the pulse frequency of ultrafast electrons leads to an increase in the complexity of DNA damages, with a consequent decrease in their reparability. Since the application of an ultrashort pulsed electron beam permits us to describe the primary radiobiological effects, it can be assumed that the observed dose-rate effect on DNA damage/repair is mainly caused by primary lesions appearing at the moment of irradiation.

scholarly journals Diminished or inversed dose-rate effect on clonogenic ability in Ku-deficient rodent cells

2020 ◽  
Author(s):  
Hisayo Tsuchiya ◽  
Mikio Shimada ◽  
Kaima Tsukada ◽  
Qingmei Meng ◽  
Junya Kobayashi ◽  
...  
Keyword(s):  
Cell Survival ◽  
Dose Rate ◽  
Biological Effects ◽  
Severe Combined Immunodeficiency ◽  
High Dose Rate ◽  
Rate Effect ◽  
High Dose ◽  
Γ Ray ◽  
Clonogenic Cell ◽  
Dose Rate Effect

Abstract The biological effects of ionizing radiation, especially those of sparsely ionizing radiations like X-ray and γ-ray, are generally reduced as the dose rate is reduced. This phenomenon is known as ‘the dose-rate effect’. The dose-rate effect is considered to be due to the repair of DNA damage during irradiation but the precise mechanisms for the dose-rate effect remain to be clarified. Ku70, Ku86 and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are thought to comprise the sensor for DNA double-strand break (DSB) repair through non-homologous end joining (NHEJ). In this study, we measured the clonogenic ability of Ku70-, Ku86- or DNA-PKcs-deficient rodent cells, in parallel with respective control cells, in response to high dose-rate (HDR) and low dose-rate (LDR) γ-ray radiation (~0.9 and ~1 mGy/min, respectively). Control cells and murine embryonic fibroblasts (MEF) from a severe combined immunodeficiency (scid) mouse, which is DNA-PKcs-deficient, showed higher cell survival after LDR irradiation than after HDR irradiation at the same dose. On the other hand, MEF from Ku70−/− mice exhibited lower clonogenic cell survival after LDR irradiation than after HDR irradiation. XR-V15B and xrs-5 cells, which are Ku86-deficient, exhibited mostly identical clonogenic cell survival after LDR and HDR irradiation. Thus, the dose-rate effect in terms of clonogenic cell survival is diminished or even inversed in Ku-deficient rodent cells. These observations indicate the involvement of Ku in the dose-rate effect.

WE-A-BRA-05: Proton Ultra High Dose-Rate Effect on HSG Cell Survival Curve

2010 ◽  
Vol 37 (6Part27) ◽  
pp. 3410-3410
Author(s):  
T Matsuura ◽  
Y Egashira ◽  
T Nishio ◽  
R Kohno ◽  
S Kameoka ◽  
...  
Keyword(s):  
Cell Survival ◽  
Dose Rate ◽  
Survival Curve ◽  
High Dose Rate ◽  
Rate Effect ◽  
High Dose ◽  
Cell Survival Curve ◽  
Dose Rate Effect

SU-GG-T-487: Lack of Dose Rate Effect with Ultra-High Dose Rate Irradiation of Normal Tissue Fibroblasts and RT112 Tumour Cells

2010 ◽  
Vol 37 (6Part23) ◽  
pp. 3299-3299
Author(s):  
R Jena ◽  
C Jeynes ◽  
J Peacock ◽  
C Thomas ◽  
S Duane ◽  
...  
Keyword(s):  
Dose Rate ◽  
Normal Tissue ◽  
High Dose Rate ◽  
Tumour Cells ◽  
Rate Effect ◽  
High Dose ◽  
Dose Rate Effect
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