Ion Beam Self Annealing in Thin Silicon Films

1988 ◽  
Vol 128 ◽  
Author(s):  
J. D. Rubio ◽  
R. P. Vijay ◽  
R. R. Hart ◽  
J. D. Pearce
Keyword(s):  
Surface Layer ◽  
Dose Rate ◽  
Thermal Annealing ◽  
Low Dose ◽  
Ion Beam ◽  
Silicon Films ◽  
Medium Energy ◽  
Lattice Disorder ◽  
Dose Rates ◽  
Complete Annealing

ABSTRACTResidual lattice disorder in lμm-thick silicon films as a function of the dose rate of 120 keV Ar+ ion implantations has been investigated. At a fluence of l×1 014 ions/cm2, low dose rates produced a highly damaged surface layer as expected; however, at a dose rate sufficient to locally heat the implanted film to a temperature of approximately 700°K, essentially complete annealing of the lattice disorder was observed. This temperature is significantly less than that normally required for post-implant thermal annealing. Measurements of lattice disorder were based on medium energy Rutherford backscattering and channeling analyses.

scholarly journals Serum Metabolomic Alterations Associated with Cesium-137 Internal Emitter Delivered in Various Dose Rates

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270
Author(s):  
Heng-Hong Li ◽  
Yun-Tien Lin ◽  
Evagelia C. Laiakis ◽  
Maryam Goudarzi ◽  
Waylon Weber ◽  
...  
Keyword(s):  
Dose Rate ◽  
Cumulative Dose ◽  
Low Dose ◽  
Biological Effects ◽  
Serum Samples ◽  
Dose Rates ◽  
Sphingosine 1 Phosphate ◽  
Cesium 137 ◽  
Dose Rate Effect ◽  
Medium Dose

Our laboratory and others have use radiation metabolomics to assess responses in order to develop biomarkers reflecting exposure and level of injury. To expand the types of exposure and compare to previously published results, metabolomic analysis has been carried out using serum samples from mice exposed to 137Cs internal emitters. Animals were injected intraperitoneally with 137CsCl solutions of varying radioactivity, and the absorbed doses were calculated. To determine the dose rate effect, serum samples were collected at 2, 3, 5, 7, and 14 days after injection. Based on the time for each group receiving the cumulative dose of 4 Gy, the dose rate for each group was determined. The dose rates analyzed were 0.16 Gy/day (low), 0.69 Gy/day (medium), and 1.25 Gy/day (high). The results indicated that at a cumulative dose of 4 Gy, the low dose rate group had the least number of statistically significantly differential spectral features. Some identified metabolites showed common changes for different dose rates. For example, significantly altered levels of oleamide and sphingosine 1-phosphate were seen in all three groups. On the other hand, the intensity of three amino acids, Isoleucine, Phenylalanine and Arginine, significantly decreased only in the medium dose rate group. These findings have the potential to be used in assessing the exposure and the biological effects of internal emitters.

Evidence for dose and dose rate effects in human and animal radiation studies

2018 ◽  
Vol 47 (3-4) ◽  
pp. 97-112 ◽  
Author(s):  
M.P. Little
Keyword(s):  
Dose Rate ◽  
Dose Response ◽  
Low Dose ◽  
Atomic Bomb ◽  
Dose Range ◽  
Quadratic Model ◽  
Linear Quadratic ◽  
Dose Rates ◽  
Atomic Bomb Survivors ◽  
Linear Quadratic Model

For stochastic effects such as cancer, linear-quadratic models of dose are often used to extrapolate from the experience of the Japanese atomic bomb survivors to estimate risks from low doses and low dose rates. The low dose extrapolation factor (LDEF), which consists of the ratio of the low dose slope (as derived via fitting a linear-quadratic model) to the slope of the straight line fitted to a specific dose range, is used to derive the degree of overestimation (if LDEF > 1) or underestimation (if LDEF < 1) of low dose risk by linear extrapolation from effects at higher doses. Likewise, a dose rate extrapolation factor (DREF) can be defined, consisting of the ratio of the low dose slopes at high and low dose rates. This paper reviews a variety of human and animal data for cancer and non-cancer endpoints to assess evidence for curvature in the dose response (i.e. LDEF) and modifications of the dose response by dose rate (i.e. DREF). The JANUS mouse data imply that LDEF is approximately 0.2–0.8 and DREF is approximately 1.2–2.3 for many tumours following gamma exposure, with corresponding figures of approximately 0.1–0.9 and 0.0–0.2 following neutron exposure. This paper also cursorily reviews human data which allow direct estimates of low dose and low dose rate risk.

BIOSYNTHESIS OF QUERCETIN IN BUCKWHEAT: PART III

1960 ◽  
Vol 38 (1) ◽  
pp. 559-567 ◽  
Author(s):  
J. E. Watkin ◽  
A. C. Neish
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Optimal Dose ◽  
Phenyllactic Acid ◽  
Maximum Percentage ◽  
Dose Rates ◽  
Percentage Conversion

The effect on the conversion of carbon14 to quercetin by a buckwheat plant caused by variation in the dose rate of a carbon 14-labelled precursor in μmoles over a 100-fold range has been studied. The results expressed as dilution of carbon14 varied over a 200-fold range for the same precursor with most of the variation being found at low dose rates. When expressed as the percentage of administered carbon14 converted to quercetin the results for acetate, D-glucose, and L-phenyllactic acid were mostly constant over this range but L-phenylalanine had a maximum percentage conversion or an optimal dose rate. An explanation of the results in metabolic terms has been attempted.It is recommended that the "percentage of C14 converted" be used to express results in plant biosynthetic work.

Influence of Low-Dose Ion-Beam Mixing on CoSi2 Formation

1992 ◽  
Vol 268 ◽  
Author(s):  
Ikasko C. Dehm ◽  
H. Ryssel
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Low Dose ◽  
Ion Beam ◽  
Ion Beam Mixing ◽  
Annealing Temperatures ◽  
Critical Dose ◽  
Incomplete Reaction ◽  
Abrupt Interface ◽  
Complete Formation

ABSTRACTIn this study, the critical dose for ion-beam mixing of Co and Si with Ge-ions which results in homogenous CoSi2 formation after rapid thermal annealing was found. For this purpose, Co was deposited by sputtering on chemically cleaned, <100>-oriented Si and subsequently mixed with Ge ions at doses in the range of 2. 1014 to 1. 1015 cm−2. Silicidation was performed in a rapid thermal annealing (RTA) system at temperatures between 700° and 100°C. Rutherford backscattering measurements showed that annealing at 700°C results in an incomplete reaction when ion-beam mixing at a dose of 2.1014 cm−2 or no ion-beam mixing was performed. After annealing at 1000°C, TEM samples revealed an inhomogeneous CoSi2 film consisting of large grains embedded in the Si. Mixing at doses at or above 5.1014 cm−2 and subsequent RTA at 700°C resulted in uniform CoSi2 layers. Higher annealing temperatures cause larger grains and resistivity values as low as 18 μΩcm. Therefore, we demonstrated that the critical dose leading to complete formation of smooth CoSi2 films with abrupt interface is 5.1014 cm−2 which is nearly the same value as the amorphization dose of Ge in Si.

Gas phase radiolysis of hydrogen chloride, hydrogen bromide, and nitrous oxide with intense electron pulses

1969 ◽  
Vol 47 (20) ◽  
pp. 3783-3791 ◽  
Author(s):  
C. Willis ◽  
A. W. Boyd ◽  
D. A. Armstrong
Keyword(s):  
Nitrous Oxide ◽  
Dose Rate ◽  
Hydrogen Chloride ◽  
Low Dose ◽  
Hydrogen Bromide ◽  
Negative Ion ◽  
Dose Rates ◽  
Electron Pulses ◽  
Intense Electron ◽  
Very High

Hydrogen chloride and hydrogen bromide have been irradiated with single electron pulses at a very high intensity (1027 eV g−1 s−1) with a Febetron 705. At room temperature the yields of hydrogen from hydrogen chloride and hydrogen bromide, for pressures between 700 and 1200 Torr, are G(H2) = 8.1 ± 0.2 and G(H2) = 9.9 ± 0.3, respectively. These are the same as the yields observed at low dose rates. Detailed lifetime calculations, however, show that the mechanism is significantly different at the higher dose rate. Scavenger experiments with chlorine in hydrogen chloride show that the negative ion intermediates form thermal hydrogen atoms.The value of G(N2) = 12.4 ± 0.2 from nitrous oxide at a dose rate of 1027 eV g−1 s−1 is confirmed and the use of nitrous oxide as a dosimeter for pulsed electron beams is discussed. The higher nitrogen yield at Febetron dose rates appears to be due to changes in the reactions of electrons.

Ion Beam Mixing and Thermal Demixing of Co/Cu Multilayers

1997 ◽  
Vol 504 ◽  
Author(s):  
M. Cai ◽  
T. Veres ◽  
R. W. Cochrane ◽  
S. Roorda ◽  
R. Abdouche ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Giant Magnetoresistance ◽  
Low Dose ◽  
Ion Beam ◽  
Ion Bombardment ◽  
Ex Situ ◽  
Ion Beam Irradiation ◽  
X Ray ◽  
Interlayer Structure ◽  
Subsequent Thermal Annealing

ABSTRACTX-ray reflectivity and magnetotransport studies have been used to probe the effects of ion-beam irradiation and subsequent thermal annealing on the structure and giant magnetoresistance (GMR) in Co/Cu multilayers. Low-dose ion bombardment produces interfacial mixing which is accompanied by a systematic suppression of the anti ferromagnetic (AF) coupling and the GMR. For ion doses not exceeding 5 × 1014 ions/cm2, subsequent thermal annealing restores the abrupt interlayer structure as well as the GMR. The combination of low-dose ion bombardment and thermal annealing provides an ex situ technique to modify interface structure reversibly over a gnificant range.

Helium Ion Beam Induced Arsenic Atom Displacement Studied by Medium-Energy Ion Spectroscopy

1993 ◽  
Vol 316 ◽  
Author(s):  
Shin Yokoyama ◽  
Zbigniew J. Radzimski ◽  
Kensaku Ishibashi ◽  
Takeshi Watanabe ◽  
Masataka Hirose
Keyword(s):  
Low Dose ◽  
Ion Beam ◽  
High Dose ◽  
Medium Energy ◽  
Arsenic Atom ◽  
Ion Beam Irradiation ◽  
Nuclear Stopping ◽  
Ion Spectroscopy ◽  
Helium Ion ◽  
Atom Displacement

ABSTRACTAn arsenic atom displacement in As+ ion implanted Si induced by He+ ion beam irradiation has been studied by medium-energy (175keV) ion spectroscopy (MEIS). The He+ energy and dose dependences of the displaced arsenic atoms have been examined in the range of 30-175keV and ≤6×10-4C/cm2, respectively. The amount of the displaced arsenic atoms are found to be proportional to the dose and inversely proportional to the nuclear stopping power in the low-dose region, while it saturates at high-dose region. The dose-proportional region is composed of two different proportional coefficient segments.

scholarly journals The effect of dose-rate on the yield of translocations and dominant lethals following spermatogonial irradiation of mice

1964 ◽  
Vol 5 (3) ◽  
pp. 468-472 ◽  
Author(s):  
R. J. S. Phillips ◽  
A. G. Searle
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Previous Experiment ◽  
Male Mice ◽  
Dose Rates ◽  
Neonatal Lethality ◽  
Full Explanation ◽  
X Irradiation ◽  
Dominant Lethals ◽  
Dose Rate Effect

1. F1 (CSH♀ × 101♂) male mice were given 1200 r. 60Co Υ-irradiation over welve weeks and mated twelve weeks after the end of irradiation. The incidences of foetal and neonatal lethality and of semi-sterility in their offspring were compared with those in controls.2. Embryonic survival to 15 days in the irradiated series was 98·2% that of controls, while the incidence of semi-sterility was 0·9% compared with nil in the controls. Neither of these differences is significant.3. Comparison of these results with the significant rates of induction of dominant lethals and translocations in a previous experiment, in which a dose of 1200 r. acute x-irradiation was given to males of the same hybrid stock, show the existence of a dose-rate effect. Its magnitude cannot at present be accurately estimated.4. The reasons for this effect are discussed. It is concluded that the main cause of the lowered translocation yield is that restitution of breaks will be favoured at low dose-rates, with less opportunity for the formation of interchanges. This could partly account for the lowered rate of induction of dominant lethals as well, but a full explanation is not yet possible.

Dose-Rate Effects of Protons and Light Ions for DNA Damage Induction, Survival and Transformation in Apparently Normal Primary Human Fibroblasts

2021 ◽  
Author(s):  
Paula V. Bennett ◽  
Alicia M. Johnson ◽  
Sarah E. Ackerman ◽  
Pankaj Chaudhary ◽  
Deborah J. Keszenman ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Survival ◽  
Dose Rate ◽  
Low Dose ◽  
Human Fibroblasts ◽  
Dose Rates ◽  
In Vitro Transformation ◽  
Dose Rate Effects ◽  
Rate Effects

We report on effects of low-dose exposures of accelerated protons delivered at high-dose rate (HDR) or a simulated solar-particle event (SPE) like low-dose rate (LDR) on immediate DNA damage induction and processing, survival and in vitro transformation of low passage NFF28 apparently normal primary human fibroblasts. Cultures were exposed to 50, 100 and 1,000 MeV monoenergetic protons in the Bragg entrance/plateau region and cesium-137 γ rays at 20 Gy/h (HDR) or 1 Gy/h (LDR). DNA double-strand breaks (DSB) and clustered DNA damages (containing oxypurines and abasic sites) were measured using transverse alternating gel electrophoresis (TAFE) and immunocytochemical detection/scoring of colocalized γ-H2AX pS139/53BP1 foci, with their induction being linear energy transfer (LET) dependent and dose-rate sparing observed for the different damage classes. Relative biological effectiveness (RBE) values for cell survival after proton irradiation at both dose-rates ranged from 0.61–0.73. Transformation RBE values were dose-rate dependent, ranging from ∼1.8–3.1 and ∼0.6–1.0 at low doses (≤30 cGy) for HDR and LDR irradiations, respectively. However peak transformation frequencies were significantly higher (1.3–7.3-fold) for higher doses of 0.5–1 Gy delivered at SPE-like LDR. Cell survival and transformation frequencies measured after low-dose 500 MeV/n He-4, 290 MeV/n C-12 and 600 MeV/n Si-28 ion irradiations also showed an inverse dose-rate effect for transformation at SPE-like LDR. This work demonstrates the existence of inverse dose-rate effects for proton and light-ion-induced postirradiation cell survival and in vitro transformation for space mission-relevant doses and dose rates.

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