Neutron radiation damage studies on silicon detectors

International Nuclear Information System (INIS)

Li, Zheng; Chen, W.; Kraner, H.W.

1990-10-01

Effects of neutron radiation on electrical properties of Si detectors have been studied. At high neutron fluence (Φ n ≥ 10 12 n/cm 2 ), C-V characteristics of detectors with high resistivities (ρ ≥ 1 kΩ-cm) become frequency dependent. A two-trap level model describing this frequency dependent effect is proposed. Room temperature anneal of neutron damaged (at LN 2 temperature) detectors shows three anneal stages, while only two anneal stages were observed in elevated temperature anneal. 19 refs., 14 figs

Production and beam annealing of damage in carbon implanted silicon

International Nuclear Information System (INIS)

Kool, W.H.; Roosendaal, H.E.; Wiggers, L.W.; Saris, F.W.

1978-01-01

The annealing of damage introduced by 70 keV C implantation of Si is studied for impact of H + and He + beams in the energy interval 30 to 200 keV. For a good description of the annealing behaviour it is necessary to account for the damage introduction which occurs simultaneously. It turns out that the initial damage annealing rate is proportional to the amount of damage. The proportionality constant is related to a quantity introduced in an earlier paper in order to describe saturation effects in the damage production after H + or He + impact in unimplanted Si. This indicates that the same mechanism governs both processes: beam induced damage annealing and saturation of the damage introduction. (author)

Cascade annealing: an overview

International Nuclear Information System (INIS)

Doran, D.G.; Schiffgens, J.O.

1976-04-01

Concepts and an overview of radiation displacement damage modeling and annealing kinetics are presented. Short-term annealing methodology is described and results of annealing simulations performed on damage cascades generated using the Marlowe and Cascade programs are included. Observations concerning the inconsistencies and inadequacies of current methods are presented along with simulation of high energy cascades and simulation of longer-term annealing

The effects of lithium counterdoping on radiation damage and annealing in n(+)p silicon solar cells

Science.gov (United States)

Weinberg, I.; Brandhorst, H. W., Jr.; Mehta, S.; Swartz, C. K.

1984-01-01

Boron-doped silicon n(+)p solar cells were counterdoped with lithium by ion implantation and the resultant n(+)p cells irradiated by 1 MeV electrons. Performance parameters were determined as a function of fluence and a deep level transient spectroscopy (DLTS) study was conducted. The lithium counterdoped cells exhibited significantly increased radiation resistance when compared to boron doped control cells. Isochronal annealing studies of cell performance indicate that significant annealing occurs at 100 C. Isochronal annealing of the deep level defects showed a correlation between a single defect at E sub v + 0.43 eV and the annealing behavior of short circuit current in the counterdoped cells. The annealing behavior was controlled by dissociation and recombination of this defect. The DLTS studies showed that counterdoping with lithium eliminated three deep level defects and resulted in three new defects. The increased radiation resistance of the counterdoped cells is due to the interaction of lithium with oxygen, single vacancies and divacancies. The lithium-oxygen interaction is the most effective in contributing to the increased radiation resistance.

Radiation annealing in cuprous oxide

DEFF Research Database (Denmark)

Vajda, P.

1966-01-01

Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square...

Minority-carrier injection-enhanced annealing of radiation damage to InGaP solar cells

International Nuclear Information System (INIS)

Yamaguchi, M.; Okuda, T.; Taylor, S.J.

1997-01-01

The observation of minority-carrier injection-enhanced annealing of radiation-induced defects in InGaP is reported. 1-MeV electron irradiation results demonstrate superior radiation-resistance of InGa 0.5 P 0.5 solar cells compared to GaAs-on-Ge cells. Moreover, minority-carrier injection under forward bias conditions is shown to enhance defect annealing in InGaP and to result in the recovery of InGaP solar cell properties. These results suggest that the radiation-resistance of InGaP-based devices such as InGaP/GaAs(/Ge) multijunction solar cells and InGaP(As) light-emitting devices is further improved under minority-carrier injection condition. copyright 1997 American Institute of Physics

Burst annealing of high temperature GaAs solar cells

Science.gov (United States)

Brothers, P. R.; Horne, W. E.

1991-01-01

One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

Burst annealing of high temperature GaAs solar cells

International Nuclear Information System (INIS)

Brothers, P.R.; Horne, W.E.

1991-01-01

One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 degree C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles

Thermal annealing of high dose radiation induced damage at room temperature in alkali halides. Stored energy, thermoluminiscence and colouration

International Nuclear Information System (INIS)

Delgado, L.

1980-01-01

The possible relation between stored energy, thermoluminiscence and colour centre annealing in gamma and electron irradiated alkali halides is studied. Thermoluminiscence occurs at temperature higher than the temperature at which the main stored energy peak appears. No stored energy release is detected in additively coloured KCl samples. Plastic deformation and doping with Ca and Sr induce a stored energy spectrum different from the spectrum observed in pure and as cleaved samples, but the amount of stored energy does not change for a given irradiation dose. Capacity of alkali halides to sotore energy by irradiation increases as the cation size decreases. It appears that most of the observed release is not related to annealing processes of the radiation induced anion Frenkel pairs. The existence of damage in the cation sublattice with which this energy release might be related is considered. (auth.)

Effect of hydration on the annealing of chemical radiation damage in gamma-irradiated strontium bromate

International Nuclear Information System (INIS)

Nair, S.M.K.; Sahish, T.S.

1991-01-01

Rehydration of γ-irradiated anhydrous strontium bromate induces direct recovery of damage. The recovery process is unimolecular and the rehydrated salt is susceptible to thermal annealing. (author) 11 refs.; 2 figs

Electron Beam Induced Radiation Damage of the Semiconductor Radiation Detector based on Silicon

International Nuclear Information System (INIS)

Kim, Han Soo; Kim, Yong Kyun; Park, Se Hwan; Haa, Jang Ho; Kang, Sang Mook; Chung, Chong Eun; Cho, Seung Yeon; Park, Ji Hyun; Yoon, Tae Hyung

2005-01-01

A Silicon Surface Barrier (SSB) semiconductor detector which is generally used to detect a charged particle such as an alpha particle was developed. The performance of the developed SSB semiconductor detector was measured with an I-V curve and an alpha spectrum. The response for an alpha particle was measured by Pu-238 sources. A SSB semiconductor detector was irradiated firstly at 30sec, at 30μA and secondly 40sec, 40μA with a 2MeV pulsed electron beam generator in KAERI. And the electron beam induced radiation damage of a homemade SSB detector and the commercially available PIN photodiode were investigated. An annealing effect of the damaged SSB and PIN diode detector were also investigated using a Rapid Thermal Annealing (RTA). This data may assist in designing the silicon based semiconductor radiation detector when it is operated in a high radiation field such as space or a nuclear power plant

Properties and recrystallization of radiation damaged pyrochlore and titanite

Energy Technology Data Exchange (ETDEWEB)

Zietlow, Peter

2016-11-02

Radiation damage in minerals is caused by the alpha-decay of incorporated radionuclides, such as U and Th and their decay products. The effect of thermal annealing (400-1400 K) on radiation-damaged pyrochlores has been investigated by Raman scattering, X-ray powder diffraction (XRD), and combined differential scanning calorimetry/thermogravimetry (DSC/TG) (Zietlow et al., in print). The analysis of three natural radiation-damaged pyrochlore samples from Miass/Russia (6.4 wt% Th, 23.1.10{sup 18} a-decay events per gram (dpg)), Zlatoust/Russia (6.3 wt% Th, 23.1.10{sup 18} dpg), Panda Hill/Tanzania (1.6 wt% Th, 1.6.10{sup 18} dpg), and Blue River/Canada (10.5 wt% U, 115.4.10{sup 18} dpg), are compared with a crystalline reference pyrochlore from Schelingen (Germany). The type of structural recovery depends on the initial degree of radiation damage (Panda Hill 28 %, Blue River 85 %, Zlatoust and Miass 100 % according to XRD), as the recrystallization temperature increases with increasing degree of amorphization. Raman spectra indicate reordering on the local scale during annealing-induced recrystallization. As Raman modes around 800 cm{sup -1} are sensitive to radiation damage (Vandenborre and Husson 1983, Moll et al. 2011), the degree of local order was deduced from the ratio of the integrated intensities of the sum of the Raman bands between 605 and 680 cm{sup -1} devided by the sum of the integrated intensities of the bands between 810 and 860 cm{sup -1}. The most radiation damaged pyrochlores (Miass and Zlatoust) show an abrupt recovery of both, its short- (Raman) and long-range order (X-ray) between 800 and 850 K. The volume decrease upon recrystallization in Zlatoust pyrochlore was large enough to crack the sample repeatedly. In contrast, the weakly damaged pyrochlore (Panda Hill) begins to recover at considerably lower temperatures (near 500 K), extending over a temperature range of ca. 300 K, up to 800 K (Raman). The pyrochlore from Blue River shows in its

Positron annihilation lifetime study of radiation-damaged natural zircons

Energy Technology Data Exchange (ETDEWEB)

Roberts, J. [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra (Australia); Gaugliardo, P. [Centre for Antimatter-Matter Studies, School of Physics, University of Western Australia (Australia); Farnan, I.; Zhang, M. [Department of Earth Sciences, University of Cambridge (United Kingdom); Vance, E.R.; Davis, J.; Karatchevtseva, I.; Knott, R.B. [Australian Nuclear Science and Technology Organisation (Australia); Mudie, S. [The Australian Synchrotron, Victoria (Australia); Buckman, S.J. [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra (Australia); Institute for Mathematical Sciences, University of Malaya, Kuala Lumpur (Malaysia); Sullivan, J.P., E-mail: james.sullivan@anu.edu.au [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra (Australia)

2016-04-01

Zircons are a well-known candidate waste form for actinides and their radiation damage behaviour has been widely studied by a range of techniques. In this study, well-characterised natural single crystal zircons have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). In some, but not all, of the crystals that had incurred at least half of the alpha-event damage of ∼10{sup 19} α/g required to render them structurally amorphous, PALS spectra displayed long lifetimes corresponding to voids of ∼0.5 nm in diameter. The long lifetimes corresponded to expectations from published Small-Angle X-ray Scattering data on similar samples. However, the non-observation by PALS of such voids in some of the heavily damaged samples may reflect large size variations among the voids such that no singular size can be distinguished or. Characterisation of a range of samples was also performed using scanning electron microscopy, optical absorption spectroscopy, Raman scattering and X-ray scattering/diffraction, with the degree of alpha damage being inferred mainly from the Raman technique and X-ray diffraction. The observed void diameters and intensities of the long lifetime components were changed somewhat by annealing at 700 °C; annealing at 1200 °C removed the voids entirely. The voids themselves may derive from He gas bubbles or voids created by the inclusion of small quantities of organic and hydrous matter, notwithstanding the observation that no voidage was evidenced by PALS in two samples containing hydrous and organic matter. - Highlights: • Study of a range of naturally occurring zircons damaged by alpha radiation. • Characterised using a range of techniques, including PALS spectroscopy. • Effects on hydrous material appear important, rather than direct radiation damage. • Annealing is shown to remove the observed voids.

Dislocations and radiation damage in α-uranium

International Nuclear Information System (INIS)

Leteurtre, J.

1969-01-01

Dislocations in α-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in α-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [fr

Study of radiation damage in metals by positron annihilation

International Nuclear Information System (INIS)

Gauster, W.B.

1977-01-01

Positron annihilation is a sensitive technique for probing defects in metals and it has recently been shown to be a valuable tool for the study of radiation damage. After an introduction to the three basic experimental methods (angular correlation, Doppler broadening, and lifetime measurements), the interaction of positrons with lattice defects is reviewed. Results for the annealing of damage after low temperature irradiation are used to show that positron annihilation has provided new information on annealing kinetics. The role of positron techniques in characterizing complex defect structures resulting from high-temperature neutron irradiation is reviewed and the possible utility of positron annihilation as a nondestructive monitor of property changes is pointed out

Facilities for studying radiation damage in nonmetals during irradiation

International Nuclear Information System (INIS)

Levy, P.W.

1984-08-01

Two facilities have been developed for making optical absorption, luminescence and other measurements on a single sample before, during and after irradiation. One facility uses 60 Co gamma rays and the other 0.5 to 3 MeV electrons from an accelerator. Optical relays function as spectrophotometers, luminescenc detectors, etc. All radiation sensitive components are outside of walk-in irradiation chambers; all measurement control and data recording is computerized. Irradiations are made at controlled temperatures between 5K and 900 0 C. The materials studied include glasses, quartz, alkali halides (especially natural rock salt), organic crystals, etc. As determined from color center measurements the damage formation rate in all materials studied at 25 0 C or above is strongly temperature dependent. The defect concentration during irradiation is usually much greater than that measured after irradiation. The fraction of defects annealing after irradiation and the annealing rate usually increases as the irradiation temperature increases. The completed studies demonstrate that, in most cases, the extent of maximum damage and the damage formation and annealing kinetics can be determined only by making measurements during irradiation

Radiation damage measurements on CZT drift strip detectors

DEFF Research Database (Denmark)

Kuvvetli, Irfan; Budtz-Jørgensen, Carl; Korsbech, Uffe C C

2003-01-01

from 2 x 10(8) to 60 x 10(8) p(+)/cm(2). Even for the highest fluences, which had a dramatic effect on the spectroscopic performance, we were able to recover the detectors after an appropriate annealing procedure. The radiation damage was studied as a function of depth inside the detector material...... with the proton dose. The radiation contribution to the electron trapping was found to obey the following relation: (mutau(e)(-1))(rad) = (2.5+/-0.2) x 10(-7) x Phi (V/cm)(2) with the proton fluence, Phi in p(+)/cm(2). The trapping depth dependence, however, did not agree well with the damage profile calculated...

Room-temperature annealing of Si implantation damage in InP

International Nuclear Information System (INIS)

Akano, U.G.; Mitchell, I.V.

1991-01-01

Spontaneous recovery at 295 K of Si implant damage in InP is reported. InP(Zn) and InP(S) wafers of (100) orientation have been implanted at room temperature with 600 keV Si + ions to doses ranging from 3.6x10 11 to 2x10 14 cm -2 . Room-temperature annealing of the resultant damage has been monitored by the Rutherford backscattering/channeling technique. For Si doses ≤4x10 13 cm -2 , up to 70% of the initial damage (displaced atoms) annealed out over a period of ∼85 days. The degree of recovery was found to depend on the initial level of damage. Recovery is characterized by at least two time constants t 1 2 ∼100 days. Anneal rates observed between 295 and 375 K are consistent with an activation energy of 1.2 eV, suggesting that the migration of implant-induced vacancies is associated with the reordering of the InP lattice

Influence of Hot Implantation on Residual Radiation Damage in Silicon Carbide

International Nuclear Information System (INIS)

Rawski, M.; Zuk, J.; Kulik, M.; Drozdziel, A.; Pyszniak, K.; Turek, M.; Lin, L.; Prucnal, S.

2011-01-01

Remarkable thermomechanical and electrical properties of silicon carbide (SiC) make this material very attractive for high-temperature, high-power, and high-frequency applications. Because of very low values of diffusion coefficient of most impurities in SiC, ion implantation is the best method to selectively introduce dopants over well-defined depths in SiC. Aluminium is commonly used for creating p-type regions in SiC. However, post-implantation radiation damage, which strongly deteriorates required electric properties of the implanted layers, is difficult to anneal even at high temperatures because of remaining residual damage. Therefore implantation at elevated target temperatures (hot implantation) is nowadays an accepted method to decrease the level of the residual radiation damage by avoiding ion beam-induced amorphization. The main objective of this study is to compare the results of the Rutherford backscattering spectroscopy with channeling and micro-Raman spectroscopy investigations of room temperature and 500 o C Al + ion implantation-induced damage in 6H-SiC and its removal by high temperature (up to 1600 o C) thermal annealing. (author)

Annealing behaviour of excess carriers in neutron-transmutation-doped silicon

International Nuclear Information System (INIS)

Maekawa, T.; Nogami, S.; Inoue, S.

1993-01-01

In neutron-transmutation-doped silicon wafers excess carriers are clearly generated over the transmuted phosphorus atoms. The generation occurs for annealing temperatures above 900 o C. The maximum percentage of excess carriers obtained is about 24.5% of the final carrier concentration. Due to the difference in energy of generation and removal, the excess carriers can be removed by annealing above 800 o C. The radiation damage responsible for generation of excess carriers is fairly thermostable in the range of annealing temperatures below 800 o C. From deep-level transient spectroscopy measurements, it is found that the radiation damage remains insensitive to changes in carrier concentration. The activation energies of excess carrier generation and removal are estimated from the analysis of the thermal and temporal behaviours of radiation damage in the annealing process. (Author)

Radiation damage studies of mineral apatite, using fission tracks and thermoluminescence techniques

International Nuclear Information System (INIS)

Al-Khalifa, I.J.M.

1988-01-01

In a uranium (/thorium)-rich mineral sample which has not suffered a recent geological high-temperature excursion, the fossil fission track density (FFTD) will give a good indication of its natural radiation damage, provided that its U/Th ratio is known. From our studies of FFTD and thermoluminescence (TL) properties of several samples of apatite from different locations, and containing varying degrees of natural-radiation damage, an anti-correlation is observed between FFTD and TL sensitivity. It is also found that an anti-correlation exists between TL sensitivity and the amount of damage produced artificially by bombarding apatite crystals with different fluences of ∼30 MeV α-particles from a cyclotron. These results indicate that the presence of radiation damage in this mineral (viz., fluorapatite) can severely affect its TL sensitivity (i.e. TL output per unit test dose). The effect of crystal composition on the thermoluminescence and fission track annealing properties of mineral apatite is also reported. We have found that fission track annealing sensitivity and TL sensitivity are both significantly lower in samples of chlorapatite than in samples consisting predominantly of fluorapatite. (author)

Effect of substrate temperature on the radiation damage from MeV Si implantation in Si

International Nuclear Information System (INIS)

Yu, X.K.; Shao Lin; Rusakova, Irene; Wang, X.M.; Ma, K.B.; Chen, H.; Liu, Jiarui; Chu, W.-K.

2006-01-01

We have investigated the radiation damage by MeV implantation of Si in Si and its evolution under thermal annealing. Si wafers were implanted with MeV Si at various substrate temperatures. Damages were characterized by Rutherford-backscattering (RBS) channeling and by transmission electron microscopy (TEM). Defect formation after post-implantation annealing is very sensitive to the substrate temperatures during implantation. When the substrate temperature was decreased to 200 K, TEM revealed two distinct bands of damage after annealing: one around the mean projected ion range and another at half the projected range. Our study indicates that the formation of defects at half range results from the solid phase epitaxy growth of initial buried amorphous layers

Radiation damage annealing mechanisms and possible low temperature annealing in silicon solar cells

Science.gov (United States)

Weinberg, I.; Swartz, C. K.

1980-01-01

Deep level transient spectroscopy and the Shockley-Read-Hall recombination theory are used to identify the defect responsible for reverse annealing in 2 ohm-cm n+/p silicon solar cells. This defect, with energy level at Ev + 0.30 eV, has been tentatively identified as a boron-oxygen-vacancy complex. It has been also determined by calculation that the removal of this defect could result in significant annealing at temperatures as low as 200 C for 2 ohm-cm and lower resistivity cells.

RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures

International Nuclear Information System (INIS)

Hallén, Anders; Moschetti, Giuseppe

2014-01-01

Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 × 10 15 cm −2 , and then annealing the samples in 365 °C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 × 10 14 cm −2 , a strong electrical resistivity increase can still be achieved

Silicon P.I.N. Junctions used for studies of radiation damage

International Nuclear Information System (INIS)

Lanore, J.

1964-06-01

Irradiation of silicon P.I.N. junction has been studied primarily for the purpose of developing a radiation damage dosimeter, but also for the purpose of investigating silicon itself. It is known that the rate of recombination of electrons and holes is a linear function of defects introduced by neutron irradiation. Two methods have been used to measure that rate of recombination: forward characteristic measurements, recovery time measurements. In order to explain how these two parameters depend on recombination rate we have given a theory of the P.I.N. junction. We have also given an idea of the carrier lifetime dependence versus temperature. Annealing effects in the range of 70 to 700 K have also been studied, we found five annealing stages with corresponding activation energies. As an application for these studies, we developed a radiation damage dosimeter with which we made several experiments in facilities such as Naiade or Marias. (author) [fr

Radiation damage testing at the SSC [Superconducting Super Collider

International Nuclear Information System (INIS)

Chinowsky, W.; Thun, R.

1990-06-01

A Task Force on Radiation Damage Testing met at the SSC Laboratory on March 5--6, 1990. This Task Force was asked to assess the availability of appropriate facilities for radiation damage tests of SSC detector materials and components. The Task Force was also instructed to review the techniques and standards for conducting such tests. Semiconductors were considered separately from other detector materials. Radiation damage test of electronic devices generally require exposures to both ionizing radiation and neutrons, whereas non-electric components such as plastic scintillating materials, adhesives, cable insulation, and other organic polymers are adequately tested with ionizing radiation only. Test standards are discussed with respect to irradiation techniques, environmental factors, dosimetry, and mechanisms whereby various materials are damaged. It is emphasized that radiation sources should be chosen to duplicate as much as possible the expected SSC environment and that the effects from ionizing particles and from neutrons be investigated separately. Radiation damage tests at reactors must be designed with particular care complex spectra of neutrons and gamma rays are produced at such facilities. It is also essential to investigate dose-rate effects since they are known to be important in many cases. The required irradiations may last several months and are most easily carried out with dedicated radioactive sources. Environmental factors such as the presence of oxygen when testing plastic scintillators, or temperature when measuring semiconductor annealing effects, must also be taken into account. The importance of reliable dosimetry is stressed and suitable references cited. Finally, it is noted that an understanding of the mechanisms for radiation damage in semiconductor and other materials is important in planning irradiations and evaluating results

Characteristics of withstanding radiation damage of InP crystals and devices

International Nuclear Information System (INIS)

Yamaguchi, Masafumi; Ando, Koshi

1988-01-01

Recently, the authors discovered that the characteristics of with standing radiation damage of InP crystals and devices (solar cells) are superior to those of Si and GaAs crystals and devices. Also the restoration phenomena at room temperature of radiation deterioration and the accelerated anneal phenomena by light irradiation and the injection of other minority, carriers in InP system devices were found. Such excellent characteristics suggested that InP devices are promising for the use in space. In this paper, taking an example of solar cells, the radiation resistance characteristics and their mechanism of InP crystals and devices are reported, based on the results of analysis by deep level transient spectroscopy and others. In InP solar cells, the high efficiency of photoelectric conversion was maintained even in the high dose irradiation of 1 MeV electron beam. As the carrier concentration in InP crystals is higher, they are stronger against radiation. With the increase of carrier concentration, the rate of anneal of radiation deterioration at room temperature increased. The accelerated anneal effect by minority carrier injection was remarkable in n + -p junction cells. The excellent characteristics of InP crystals are due to the formation of Frenkel defects of P and their instability. (K.I.)

Semiconductor annealing

International Nuclear Information System (INIS)

Young, J.M.; Scovell, P.D.

1981-01-01

A process for annealing crystal damage in ion implanted semiconductor devices is described in which the device is rapidly heated to a temperature between 450 and 600 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. The process may be enhanced by the application of optical radiation from a Xenon lamp. (author)

Radiation damage in proton-irradiated epitaxial silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Lange, Joern

2009-07-15

In this work radiation hardness of 75 {mu}m, 100 {mu}m and 150 {mu}m thick epitaxial silicon pad diodes of both standard and oxygenated material was investigated. Damage after 24 GeV/c proton irradiation in a 1MeV neutron equivalent fluence range between 10{sup 14} cm{sup -2} and 10{sup 16} cm{sup -2} was studied and isothermal annealing experiments at 80 C were carried out. Standard CV/IV measurements could be performed up to 4 x 10{sup 15} cm{sup -2}. The volume-normalised reverse current was found to increase linearly with fluence with a slope independent of the thickness and impurity concentration. However, due to large fluctuations the fluences had to be renormalised using the current-related damage parameter. Concerning the depletion voltage, nearly all materials remained at a moderate level up to 4 x 10{sup 15} cm{sup -2}. During short-term annealing acceptors annealed out, whereas others were introduced during the long-term annealing. The stable damage was characterised by donor removal at low fluences and fluence-proportional predominant donor introduction for highly irradiated diodes, depending on the oxygen level. No type inversion was observed. Time-resolved measurements with a new 670 nm laser-TCT setup made the determination of the trapping time constant with the charge correction method possible. The results agreed with expectations and showed a linear increase of trapping probability with fluence. The electric field exhibited a double peak structure in highly irradiated diodes. Charge collection efficiency measurements with {alpha}-particles were independent of oxygen concentration, but showed an improved efficiency for thinner diodes. A comparison to simulation revealed systematic discrepancies. A non-constant trapping time parameter was proposed as possible solution. (orig.)

Radiation damage in proton-irradiated epitaxial silicon detectors

International Nuclear Information System (INIS)

Lange, Joern

2009-07-01

In this work radiation hardness of 75 μm, 100 μm and 150 μm thick epitaxial silicon pad diodes of both standard and oxygenated material was investigated. Damage after 24 GeV/c proton irradiation in a 1MeV neutron equivalent fluence range between 10 14 cm -2 and 10 16 cm -2 was studied and isothermal annealing experiments at 80 C were carried out. Standard CV/IV measurements could be performed up to 4 x 10 15 cm -2 . The volume-normalised reverse current was found to increase linearly with fluence with a slope independent of the thickness and impurity concentration. However, due to large fluctuations the fluences had to be renormalised using the current-related damage parameter. Concerning the depletion voltage, nearly all materials remained at a moderate level up to 4 x 10 15 cm -2 . During short-term annealing acceptors annealed out, whereas others were introduced during the long-term annealing. The stable damage was characterised by donor removal at low fluences and fluence-proportional predominant donor introduction for highly irradiated diodes, depending on the oxygen level. No type inversion was observed. Time-resolved measurements with a new 670 nm laser-TCT setup made the determination of the trapping time constant with the charge correction method possible. The results agreed with expectations and showed a linear increase of trapping probability with fluence. The electric field exhibited a double peak structure in highly irradiated diodes. Charge collection efficiency measurements with α-particles were independent of oxygen concentration, but showed an improved efficiency for thinner diodes. A comparison to simulation revealed systematic discrepancies. A non-constant trapping time parameter was proposed as possible solution. (orig.)

Radiation damage in silicon exposed to high-energy protons

International Nuclear Information System (INIS)

Davies, Gordon; Hayama, Shusaku; Murin, Leonid; Krause-Rehberg, Reinhard; Bondarenko, Vladimir; Sengupta, Asmita; Davia, Cinzia; Karpenko, Anna

2006-01-01

Photoluminescence, infrared absorption, positron annihilation, and deep-level transient spectroscopy (DLTS) have been used to investigate the radiation damage produced by 24 GeV/c protons in crystalline silicon. The irradiation doses and the concentrations of carbon and oxygen in the samples have been chosen to monitor the mobility of the damage products. Single vacancies (and self-interstitials) are introduced at the rate of ∼1 cm -1 , and divacancies at 0.5 cm -1 . Stable di-interstitials are formed when two self-interstitials are displaced in one damage event, and they are mobile at room temperature. In the initial stages of annealing the evolution of the point defects can be understood mainly in terms of trapping at the impurities. However, the positron signal shows that about two orders of magnitude more vacancies are produced by the protons than are detected in the point defects. Damage clusters exist, and are largely removed by annealing at 700 to 800 K, when there is an associated loss of broad band emission between 850 and 1000 meV. The well-known W center is generated by restructuring within clusters, with a range of activation energies of about 1.3 to 1.6 eV, reflecting the disordered nature of the clusters. Comparison of the formation of the X centers in oxygenated and oxygen-lean samples suggests that the J defect may be interstitial related rather than vacancy related. To a large extent, the damage and annealing behavior may be factorized into point defects (monitored by sharp-line optical spectra and DLTS) and cluster defects (monitored by positron annihilation and broadband luminescence). Taking this view to the limit, the generation rates for the point defects are as predicted by simply taking the damage generated by the Coulomb interaction of the protons and Si nuclei

Inverted Apatite (U-Th)/He and Fission-track Dates from the Rae craton, Baffin Island, Canada and Implications for Apatite Radiation Damage-He Diffusivity Models

Science.gov (United States)

Ault, A. K.; Reiners, P. W.; Thomson, S. N.; Miller, G. H.

2015-12-01

Coupled apatite (U-Th)/He and fission-track (AFT) thermochronology data from the same sample can be used to decipher complex low temperature thermal histories and evaluate compatibility between these two methods. Existing apatite He damage-diffusivity models parameterize radiation damage annealing as fission-track annealing and yield inverted apatite He and AFT dates for samples with prolonged residence in the He partial retention zone. Apatite chemistry also impacts radiation damage and fission-track annealing, temperature sensitivity, and dates in both systems. We present inverted apatite He and AFT dates from the Rae craton, Baffin Island, Canada, that cannot be explained by apatite chemistry or existing damage-diffusivity and fission track models. Apatite He dates from 34 individual analyses from 6 samples range from 237 ± 44 Ma to 511 ± 25 Ma and collectively define a positive date-eU relationship. AFT dates from these same samples are 238 ± 15 Ma to 350 ± 20 Ma. These dates and associated track length data are inversely correlated and define the left segment of a boomerang diagram. Three of the six samples with 20-90 ppm eU apatite grains yield apatite He and AFT dates inverted by 300 million years. These samples have average apatite Cl chemistry of ≤0.02 wt.%, with no correlation between Cl content and Dpar. Thermal history simulations using geologic constraints, an apatite He radiation damage accumulation and annealing model, apatite He dates with the range of eU values, and AFT date and track length data, do not yield any viable time-temperature paths. Apatite He and AFT data modeled separately predict thermal histories with Paleozoic-Mesozoic peaks reheating temperatures differing by ≥15 °C. By modifying the parameter controlling damage annealing (Rmr0) from the canonical 0.83 to 0.5-0.6, forward models reproduce the apatite He date-eU correlation and AFT dates with a common thermal history. Results imply apatite radiation damage anneals at

Damage recovery in ZnO by post-implantation annealing

International Nuclear Information System (INIS)

Audren, A.; Hallen, A.; Linnarsson, M.K.; Possnert, G.

2010-01-01

ZnO bulk samples were implanted with 200 keV-Co ions at room temperature with two fluences, 1 x 10 16 and 8 x 10 16 cm -2 , and then annealed in air for 30 min at different temperatures up to 900 o C. After the implantation and each annealing step, the samples were analyzed by Rutherford backscattering spectrometry (RBS) in random and channeling directions to follow the evolution of the disorder profile. The RBS spectra reveal that disorder is created during implantation in proportion to the Co fluence. The thermal treatments induce a disorder recovery, which is however, not complete after annealing at 900 o C, where about 15% of the damage remains. To study the Co profile evolution during annealing, the samples were, in addition to RBS, characterized by secondary ion mass spectrometry (SIMS). The results show that Co diffusion starts at 800 o C, but also that a very different behavior is seen for Co concentrations below and above the solubility limit.

Effect of pressure on the radiation annealing of recoil atoms in chromates

International Nuclear Information System (INIS)

Stamouli, M.I.

1986-01-01

The effect of pressure on the annealing of recoil atoms by gamma radiation in neutron irradiated potassium chromate, ammonium chromate and ammonium dichromate was studied. In potassium chromate the pressure applied before the gamma-irradiation was found to retard the radiation annealing process. In ammonium chromate and ammonium dichromate the radiation annealing was found to be enhanced in the compressed samples in comparison to the noncompressed ones. (author)

Annealing simulation of cascade damage using MARLOWE-DAIQUIRI codes

International Nuclear Information System (INIS)

Muroga, Takeo

1984-01-01

The localization effect of the defects generated by the cascade damage on the properties of solids was studied by using a computer code. The code is based on the two-body collision approximation method and the Monte Carlo method. The MARLOWE and DAIQUIRI codes were partly improved to fit the present calculation of the annealing of cascade damage. The purpose of this study is to investigate the behavior of defects under the simulated reactive and irradiation condition. Calculation was made for alpha iron (BCC), and the threshold energy was set at 40 eV. The temperature dependence of annealing and the growth of a cluster were studied. The overlapping effect of cascade was studied. At first, the extreme case of overlapping was studied, then the practical cases were estimated by interpolation. The state of overlapping of cascade corresponded to the irradiation speed. The interaction between cascade and dislocations was studied, and the calculation of the annealing of primary knock-out atoms (PKA) in alpha iron was performed. At low temperature, the effect of dislocations was large, but the growth of vacancy was not seen. At high temperature, the effect of dislocations was small. The evaluation of the simulation of various ion irradiation and the growth efficiency of defects were performed. (Kato, T.)

Damage accumulation and annealing in 6H-SiC irradiated with Si+

International Nuclear Information System (INIS)

Jiang, W.; Weber, W.J.; Thevuthasan, S.; McCready, D.E.

1998-01-01

Damage accumulation and annealing in 6H-silicon carbide (α-SiC) single crystals have been studied in situ using 2.0 MeV He + RBS in a left angle 0001 right angle -axial channeling geometry (RBS/C). The damage was induced by 550 keV Si + ion implantation (30 off normal) at a temperature of -110 C, and the damage recovery was investigated by subsequent isochronal annealing (20 min) over the temperature range from -110 C to 900 C. At ion fluences below 7.5 x 10 13 Si + /cm 2 (0.04 dpa in the damage peak), only point defects appear to be created. Furthermore, the defects on the Si sublattice can be completely recovered by thermal annealing at room temperature (RT), and recovery of defects on the C sublattice is suggested. At higher fluences, amorphization occurs; however, partial damage recovery at RT is still observed, even at a fluence of 6.6 x 10 14 Si + /cm 2 (0.35 dpa in the damage peak) where a buried amorphous layer is produced. At an ion fluence of 6.0 x 10 15 Si + /cm 2 (-90 C), an amorphous layer is created from the surface to a depth of 0.6 μm. Because of recovery processes at the buried crystalline-amorphous interface, the apparent thickness of this amorphous layer decreases slightly (<10%) with increasing temperature over the range from -90 C to 600 C. (orig.)

Low dose radiation damage effects in silicon strip detectors

International Nuclear Information System (INIS)

Wiącek, P.; Dąbrowski, W.

2016-01-01

The radiation damage effects in silicon segmented detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL). However, radiation damage in silicon strip is observed not only after extreme doses up to 1 GGy expected at E-XFEL, but also at doses in the range of tens of Gy, to which the detectors in laboratory instruments like X-ray diffractometers or X-ray spectrometers can be exposed. In this paper we report on investigation of radiation damage effects in a custom developed silicon strip detector used in laboratory diffractometers equipped with X-ray tubes. Our results show that significant degradation of detector performance occurs at low doses, well below 200 Gy, which can be reached during normal operation of laboratory instruments. Degradation of the detector energy resolution can be explained by increasing leakage current and increasing interstrip capacitance of the sensor. Another observed effect caused by accumulation of charge trapped in the surface oxide layer is change of charge division between adjacent strips. In addition, we have observed unexpected anomalies in the annealing process.

Low dose radiation damage effects in silicon strip detectors

Science.gov (United States)

Wiącek, P.; Dąbrowski, W.

2016-11-01

The radiation damage effects in silicon segmented detectors caused by X-rays have become recently an important research topic driven mainly by development of new detectors for applications at the European X-ray Free Electron Laser (E-XFEL). However, radiation damage in silicon strip is observed not only after extreme doses up to 1 GGy expected at E-XFEL, but also at doses in the range of tens of Gy, to which the detectors in laboratory instruments like X-ray diffractometers or X-ray spectrometers can be exposed. In this paper we report on investigation of radiation damage effects in a custom developed silicon strip detector used in laboratory diffractometers equipped with X-ray tubes. Our results show that significant degradation of detector performance occurs at low doses, well below 200 Gy, which can be reached during normal operation of laboratory instruments. Degradation of the detector energy resolution can be explained by increasing leakage current and increasing interstrip capacitance of the sensor. Another observed effect caused by accumulation of charge trapped in the surface oxide layer is change of charge division between adjacent strips. In addition, we have observed unexpected anomalies in the annealing process.

Low-temperature annealing of radiation defects in electron-irradiated gallium phosphide

International Nuclear Information System (INIS)

Kolb, A.A.; Megela, I.G.; Buturlakin, A.P.; Goyer, D.B.

1990-01-01

The isochronal annealing of radiation defects in high-energy electron irradiated n-GaP monocrystals within the 77 to 300 K range has been investigated by optical and electrical techniques. The changes in conductance and charge carrier mobility as functions of annealing temperature as well as the variation of optical absorption spectra of GaP under irradiation and annealing provide evidence that most of radiation defects are likely secondary complexes of defects

Radiation damages in superconducting materials

International Nuclear Information System (INIS)

Heinz, W.; Seibt, E.

1978-01-01

Radiation damage investigations of technical superconductors are reported and discussed with respect to their main properties like critical current jsub(c), transition temperature Tsub(c), upper critical field Bsub(c2), pinning and annealing behaviour. Ordered A15 type alloys (like Nb 3 Sn and V 3 Ga) show significant reductions of all critical parameters above a threshold of about 2x10 21 m -2 with 50 MeV deuterons corresponding to 2x10 22 neutrons/m 2 (Esub(n)>0.1 MeV). Pure metals and disordered B1 type alloys (like Nb or NbTi) show only a small linear decrease in critical parameters (except Bsub(c2) of niobium). Experimental results are compared with theoretical calculations. (author)

Burst annealing of electron damage in silicon solar cells

International Nuclear Information System (INIS)

Day, A.C.; Horne, W.E.; Thompson, M.A.; Lancaster, C.A.

1985-01-01

A study has been performed of burst annealing of electron damage in silicon solar cells. Three groups of cells consisting of 3 and 0.3 ohm-cm silicon were exposed to fluences of 2 x 10 to the 14th power, 4 x 10 to the 14th power, and 8 x 10 to the 14th power 1-MeV electrons/sq cm, respectively. They were subsequently subjected to 1-minute bursts of annealing at 500 C. The 3 ohm-cm cells showed complete recovery from each fluence level. The 0.3 ohm-cm cells showed complete recovery from the 2 x 10 to the 14th power e/sq cm fluence; however, some of the 0.3 ohm-cm cells did not recover completely from the higher influences. From an analysis of the results it is concluded that burst annealing of moderate to high resistivity silicon cell arrays in space is feasible and that with more complete understanding, even the potentially higher efficiency low resistivity cells may be usable in annealable arrays in space

Radiation-Induced Damage and Recovery of Ultra-Nanocrystalline Diamond: Toward Applications in Harsh Environments.

Science.gov (United States)

Martin, Aiden A; Filevich, Jorge; Straw, Marcus; Randolph, Steven; Botman, Aurélien; Aharonovich, Igor; Toth, Milos

2017-11-15

Ultra-nanocrystalline diamond (UNCD) is increasingly being used in the fabrication of devices and coatings due to its excellent tribological properties, corrosion resistance, and biocompatibility. Here, we study its response to irradiation with kiloelectronvolt electrons as a controlled model for extreme ionizing environments. Real time Raman spectroscopy reveals that the radiation-damage mechanism entails dehydrogenation of UNCD grain boundaries, and we show that the damage can be recovered by annealing at 883 K. Our results have significant practical implications for the implementation of UNCD in extreme environment applications, and indicate that the films can be used as radiation sensors.

A study of the effect of natural radiation damage in a zircon crystal using thermoluminescence, fission track etching and X-ray diffraction

International Nuclear Information System (INIS)

Amin, Y.M.

1989-01-01

The natural radiation damage in zircon caused by the decay of uranium and thorium, present as impurities, is studied. The radiation damage is first gauged by etching the fission tracks. It is found that thermoluminescence (TL) sensitivity (defined as light output per unit test-dose) decreases as the radiation damage increases, suggesting a destruction of TL centers. The spacing d of the (112)-plane is also measured. It is also found that the d-value increases with radiation damage, suggesting the displacement of atoms from their normal lattice sites. However, as the track density increases beyond ≅ 3x10 6 tracks/cm 2 , the d-value remains at ≅ 2.52 A. By annealing the crystal, the displaced atoms are found to return to the original lattice sites, and this is followed by a reduction in d-value as well as the recovery of TL sensitivity. The fission track density also decreases and all the tracks disappear at the annealing temperature of ≅ 800 0 C. (orig.)

Radiation damages and electro-conductive characteristics of Neutron-Transmutation-Doped GaAs

Energy Technology Data Exchange (ETDEWEB)

Kuriyama, Kazuo; Sato, Masataka; Sakai, Kiyohiro [Hosei Univ., Koganei, Tokyo (Japan). Coll. of Engineering; Okada, Moritami

1996-04-01

Neutron Transmutation Doping (NTD) method made it possible to do homogeneous doping of impurities and to easily control the doping level. Thus, the method has been put into practice for some materials such as silicon. Here, the annealing behavior of anti-site defects generated in neutron-irradiated GaAs was studied. Electric activations of NTD-impurities were started around 550degC in P1 and P2 radiation fields, which were coincident with the beginning of extinction of electron trapping which was caused by anti-site defects due to fast neutron radiation. The electric resistivities of GaAs in neutron radiation fields; P1, P2 and P3 changed depending with the annealing temperature. The electric resistivities of GaAs in P1 and P2 fields indicate the presence of hopping conduction through radiation damages. The resistance of GaAs irradiated in P1 was smaller by nearly 2 orders than that of the untreated control. Further, the electric activation process for NTD-impurities was investigated using ESR and Raman spectroscopy. (M.N.)

Effect of radiation damage on the infrared properties of apatite

International Nuclear Information System (INIS)

Anis Faridah Md Nori; Yusof Mohd Amin; Rosli Mahat; Burhanuddin Kamaluddin

1991-01-01

Apatites are known to contain radioactive elements such as uranium and thorium at a few ppm in concentration. These elements decay and produce fission tracks inside the crystals. The presence of such tracks have been known to affect the thermoluminescence (TL) properties of apatites. These fission tracks can be removed by annealing the crystals in air. In this paper we present the result of a preliminary study on the effect of radiation damage on the infrared transmission of apatites

Annealing effects on the migration of ion-implanted cadmium in glassy carbon

Energy Technology Data Exchange (ETDEWEB)

Hlatshwayo, T.T., E-mail: thulani.hlatshwayo@up.ac.za [Physics Department, University of Pretoria, Pretoria (South Africa); Sebitla, L.D. [Physics Department, University of Pretoria, Pretoria (South Africa); Physics Department, University of Botswana, Gaborone (Botswana); Njoroge, E.G.; Mlambo, M.; Malherbe, J.B. [Physics Department, University of Pretoria, Pretoria (South Africa)

2017-03-15

The migration behaviour of cadmium (Cd) implanted into glassy carbon and the effects of annealing on radiation damage introduced by ion implantation were investigated. The glassy carbon substrates were implanted with Cd at a dose of 2 × 10{sup 16} ions/cm{sup 2} and energy of 360 keV. The implantation was performed at room temperature (RT), 430 °C and 600 °C. The RT implanted samples were isochronally annealed in vacuum at 350, 500 and 600 °C for 1 h and isothermally annealed at 350 °C up to 4 h. The as-implanted and annealed samples were characterized by Raman spectroscopy and Rutherford backscattering spectrometry (RBS). Raman results revealed that implantation at room temperature amorphized the glassy carbon structure while high temperature implantations resulted in slightly less radiation damage. Isochronal annealing of the RT implanted samples resulted in some recrystallization as a function of increasing temperature. The original glassy carbon structure was not achieved at the highest annealing temperature of 600 °C. Diffusion of Cd in glassy carbon was already taking place during implantation at 430 °C. This diffusion of Cd was accompanied by significant loss from the surface during implantation at 600 °C. Isochronal annealing of the room temperature implanted samples at 350 °C for 1 h caused Cd to diffuse towards the bulk while isothermal annealing at 500 and 600 °C resulted in the migration of implanted Cd toward the surface accompanied by a loss of Cd from the surface. Isothermal annealing at 350 °C for 1 h caused Cd to diffuse towards the bulk while for annealing time >1 h Cd diffused towards the surface. These results were interpreted in terms of trapping and de-trapping of implanted Cd by radiation damage.

Influence of radiation damage evolution on lattice-location, measurements for Yb and Au in iron

International Nuclear Information System (INIS)

Cohen, C.; Abel, F.; Bruneaux, M.; Thome, L.; Bernas, H.; Chaumont, J.

1978-01-01

The influence of radiation damage on lattice-location of heavy impurities (Yb and Au) implanted in iron is studied by channeling experiments. The nature of the impurity-radiation damage interaction has been modified by annealing of room-temperature implanted samples or high temperature implantation. The value of the corrected extinction ratio epsilon measured in several crystallographic directions on room-temperature implanted Yb and Au impurities cannot be interpreted uniquely in terms of different site populations. The annealing and implantation temperature dependences of the ratio epsilon for Yb-implanted Fe are very different. Upon annealing, the value of epsilon is unchanged up to 420 0 C and then drops abruptly. In hot-implant experiments, the extinction ratio starts to fall at approximately 150 0 C when vacancies become mobile. Vacancy-assisted diffusion is suggested to cause the changes of epsilon in both experiments. The temperature dependence of epsilon for the (100) plane is found to differ from that in other directions. This planar effect suggests that Yb impurities move preferentially in the (100) plane, which is the plane of vacancy-loops in Fe. A quantitative analysis of these lattice-location results and of related hyperfne interaction results is presented in a companion paper

Annealing of proton-damaged GaAs and 1/f noise

NARCIS (Netherlands)

Chen, X.Y.; Folter, de L.C.

1997-01-01

GaAs layers were grown by MBE. The layers were then damaged by 3 MeV proton irradiation and later annealed. We performed Hall effect and low-frequency noise measurements at temperatures between 77 K and 300 K after each step. Several generation - recombination noise components created by proton

Radiation damage

CERN Document Server

Heijne, Erik H M; CERN. Geneva

1998-01-01

a) Radiation damage in organic materials. This series of lectures will give an overview of radiation effects on materials and components frequently used in accelerator engineering and experiments. Basic degradation phenomena will be presented for organic materials with comprehensive damage threshold doses for commonly used rubbers, thermoplastics, thermosets and composite materials. Some indications will be given for glass, scintillators and optical fibres. b) Radiation effects in semiconductor materials and devices. The major part of the time will be devoted to treat radiation effects in semiconductor sensors and the associated electronics, in particular displacement damage, interface and single event phenomena. Evaluation methods and practical aspects will be shown. Strategies will be developed for the survival of the materials under the expected environmental conditions of the LHC machine and detectors. I will describe profound revolution in our understanding of black holes and their relation to quantum me...

Propagating self-sustained annealing of radiation-induced interstitial complexes

International Nuclear Information System (INIS)

Bokov, P M; Selyshchev, P A

2016-01-01

A propagating self-sustained annealing of radiation induced defects as a result of thermal-concentration instability is studied. The defects that are considered in the model are complexes. Each of them consists of one atom of impunity and of one interstitial atom. Crystal with defects has extra energy which is transformed into heat during defect annealing. Simulation of the auto-wave of annealing has been performed. The front and the speed of the auto-wave have been obtained. It is shown that annealing occurs in a narrow region of time and space. There are two kinds of such annealing behaviour. In the first case the speed of the auto-wave oscillates near its constant mean value and the front of temperature oscillates in a complex way. In the second case the speed of propagation is constant and fronts of temperature and concentration look like sigmoid functions. (paper)

Cross-section transmission electron microscopy of the ion implantation damage in annealed diamond

Energy Technology Data Exchange (ETDEWEB)

Derry, T.E. [DST/NRF Centre of Excellence in Strong Materials and School of Physics, University of the Witwatersrand, Wits 2050, Johannesburg (South Africa)], E-mail: Trevor.Derry@wits.ac.za; Nshingabigwi, E.K. [DST/NRF Centre of Excellence in Strong Materials and School of Physics, University of the Witwatersrand, Wits 2050, Johannesburg (South Africa); Department of Physics, National University of Rwanda, P.O. Box 117, Huye (Rwanda); Levitt, M. [DST/NRF Centre of Excellence in Strong Materials and School of Physics, University of the Witwatersrand, Wits 2050, Johannesburg (South Africa); Neethling, J. [DST/NRF CoE-SM and Physics Department, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Naidoo, S.R. [DST/NRF Centre of Excellence in Strong Materials and School of Physics, University of the Witwatersrand, Wits 2050, Johannesburg (South Africa)

2009-08-15

It has formerly been shown that low-damage levels, produced during the implantation doping of diamond as a semiconductor, anneal easily while high levels 'graphitize' (above about 5.2 x 10{sup 15} ions/cm{sup 2}). The difference in the defect types and their profiles, in the two cases, has never been directly observed. We have succeeded in using cross-section transmission electron microscopy to do so. The experiments were difficult because the specimens must be polished to {approx}40 {mu}m thickness, then implanted on edge and annealed, before final ion beam thinning to electron transparency. The low-damage micrographs reveal some deeply penetrating dislocations, whose existence had been predicted in earlier work.

Cross-section transmission electron microscopy of the ion implantation damage in annealed diamond

International Nuclear Information System (INIS)

Derry, T.E.; Nshingabigwi, E.K.; Levitt, M.; Neethling, J.; Naidoo, S.R.

2009-01-01

It has formerly been shown that low-damage levels, produced during the implantation doping of diamond as a semiconductor, anneal easily while high levels 'graphitize' (above about 5.2 x 10 15 ions/cm 2 ). The difference in the defect types and their profiles, in the two cases, has never been directly observed. We have succeeded in using cross-section transmission electron microscopy to do so. The experiments were difficult because the specimens must be polished to ∼40 μm thickness, then implanted on edge and annealed, before final ion beam thinning to electron transparency. The low-damage micrographs reveal some deeply penetrating dislocations, whose existence had been predicted in earlier work.

Study of crosslinking onset and hydrogen annealing of ultra-high molecular weight polyethylene irradiated with high-energy protons

Science.gov (United States)

Wilson, John Ford

1997-09-01

Ultra high molecular weight polyethylene (UHMW-PE) is used extensively in hip and knee endoprostheses. Radiation damage from the sterilization of these endoprostheses prior to surgical insertion results in polymer crosslinking and decreased oxidative stability. The motivation for this study was to determine if UHMW-PE could be crosslinked by low dose proton irradiation with minimal radiation damage and its subsequent deleterious effects. I found that low dose proton irradiation and post irradiation hydrogen annealing did crosslink UHMW-PE and limit post irradiation oxidation. Crosslinking onset was investigated for UHMW-PE irradiated with 2.6 and 30 MeV H+ ions at low doses from 5.7 × 1011-2.3 × 1014 ions/cm2. Crosslinking was determined from gel permeation chromatography (GPC) of 1,2,4 trichlorobenzene sol fractions and increased with dose. Fourier transform infrared spectroscopy (FTIR) showed irradiation resulted in increased free radicals confirmed from increased carbonyl groups. Radiation damage, especially at the highest doses observed, also showed up in carbon double bonds and increased methyl end groups. Hydrogen annealing after ion irradiation resulted in 40- 50% decrease in FTIR absorption associated with carbonyl. The hydrogen annealing prevented further oxidation after aging for 1024 hours at 80oC. Hydrogen annealing was successful in healing radiation damage through reacting with the free radicals generated during proton irradiation. Polyethylenes, polyesters, and polyamides are used in diverse applications by the medical profession in the treatment of orthopedic impairments and cardiovascular disease and for neural implants. These artificial implants are sterilized with gamma irradiation prior to surgery and the resulting radiation damage can lead to accelerated deterioration of the implant properties. The findings in this study will greatly impact the continued use of these materials through the elimination of many problems associated with radiation

Unified model of damage annealing in CMOS, from freeze-in to transient annealing

International Nuclear Information System (INIS)

Sander, H.H.; Gregory, B.L.

Results of an experimental study at 76 0 K, are presented showing that radiation-produced holes in SiO 2 are immobile at this temperature. If an electric field is present in the SiO 2 during low temperature (76 0 K) irradiation to sweep out the mobile electrons, the holes will virtually all be trapped where created and produce a uniform positive charge density in the oxide. These results are the basis for concluding that if a complimentary p,n metal-oxide semiconductor (CMOS) device is irradiated for sufficient time at 76 0 K to build-in an appreciable field, further irradiation with gate bias removed will produce very little additional change in V/sub th/, since the field in the oxide tends to keep all generated electrons in the oxide where they recombine with trapped holes. Hence the hole trapping rate = the hole annihilation rate. The room-temperature annealing following a pulsed gamma exposure occurs in two regimes. The first recovery of V/sub th/ occurs prior to 10 -4 seconds. The magnitude of this very early-time recovery, at room temperature, is oxide-dependent, and oxide process dependent. The rate-of-annealing is what is truly different between a rad-hard and a rad-soft device, since annealing in the hardest devices occurs very quickly at room temperature. (U.S.)

Effect of Pre-Irradiation Annealing and Laser Modification on the Formation of Radiation-Induced Surface Color Centers in Lithium Fluoride

Science.gov (United States)

Voitovich, A. P.; Kalinov, V. S.; Novikov, A. N.; Radkevich, A. V.; Runets, L. P.; Stupak, A. P.; Tarasenko, N. V.

2017-01-01

It is shown that surface color centers of the same type are formed in the surface layer and in regions with damaged crystal structure inside crystalline lithium fluoride after γ-irradiation. Results are presented from a study of the effect of pre-irradiation annealing on the efficiency with which surface centers are formed in lithium fluoride nanocrystals. Raising the temperature for pre-irradiation annealing from room temperature to 250°C leads to a substantial reduction in the efficiency with which these centers are created. Surface color centers are not detected after γ-irradiation for pre-irradiation annealing temperatures of 300°C and above. Adsorption of atmospheric gases on the crystal surface cannot be regarded as a necessary condition for the formation of radiation-induced surface centers.

Molecular dynamics study of radiation damage and microstructure evolution of zigzag single-walled carbon nanotubes under carbon ion incidence

Science.gov (United States)

Li, Huan; Tang, Xiaobin; Chen, Feida; Huang, Hai; Liu, Jian; Chen, Da

2016-07-01

The radiation damage and microstructure evolution of different zigzag single-walled carbon nanotubes (SWCNTs) were investigated under incident carbon ion by molecular dynamics (MD) simulations. The radiation damage of SWCNTs under incident carbon ion with energy ranging from 25 eV to 1 keV at 300 K showed many differences at different incident sites, and the defect production increased to the maximum value with the increase in incident ion energy, and slightly decreased but stayed fairly stable within the majority of the energy range. The maximum damage of SWCNTs appeared when the incident ion energy reached 200 eV and the level of damage was directly proportional to incident ion fluence. The radiation damage was also studied at 100 K and 700 K and the defect production decreased distinctly with rising temperature because radiation-induced defects would anneal and recombine by saturating dangling bonds and reconstructing carbon network at the higher temperature. Furthermore, the stability of a large-diameter tube surpassed that of a thin one under the same radiation environments.

Radiation damage of nonmetallic solids

International Nuclear Information System (INIS)

Goland, A.N.

1975-01-01

A review of data and information on radiation damage in nonmetallic solids is presented. Discussions are included on defects in nonmetals, radiation damage processes in nonmetals, electronic damage processes, physical damage processes, atomic displacement, photochemical damage processes, and ion implantation

Kinetics of annealing of irradiated surveillance pressure vessel steel

International Nuclear Information System (INIS)

Harvey, D.J.; Wechsler, M.S.

1982-01-01

Indentation hardness measurements as a function of annealing were made on broken halves of Charpy impact surveillance samples. The samples had been irradiated in commercial power reactors to a neutron fluence of approximately 1 x 10 18 neutrons per cm 2 , E > 1 MeV, at a temperature of about 300 0 C (570 0 F). Results are reported for the weld metal, which showed greater radiation hardening than the base plate or heat-affected zone material. Isochronal and isothermal anneals were conducted on the irradiated surveillance samples and on unirradiated control samples. No hardness changes upon annealing occurred for the control samples. The recovery in hardness for the irradiated samples took place mostly between 400 and 500 0 C. Based on the Meechan-Brinkman method of analysis, the activation energy for annealing was found to be 0.60 +- 0.06 eV. According to computer simulation calculations of Beeler, the activation energy for migration of vacancies in alpha iron is about 0.67 eV. Therefore, the results of this preliminary study appear to be consistent with a mechanism of annealing of radiation damage in pressure vessel steels based on the migration of radiation-produced lattice vacancies

Thermoluminescence of annealed and shock-loaded feldspar

International Nuclear Information System (INIS)

Hartmetz, C.P.

1988-01-01

Samples of oligoclase and bytownite were shock-loaded to a variety of pressures, and annealed for a variety of temperatures and times. The effect of Mrad doses of gamma-rays on oligoclase TL were also studied. After these treatments, thermoluminescence (TL) and X-ray diffraction (XRD) measurements were made to: (1) determine the effects of shock on terrestrial feldspar and compare with variations in the TL emission of ordinary chondrites (OCs); (2) determine if disordering in feldspar was responsible for any related changes in TL properties of OCs; (3) determine if the combined effect of shock plus annealing causes the changes in TL properties; (4) see if radiation damage from cosmic ray exposure plays a role in the TL variations; (5) examine the implications of this work to the thermal and shock histories of OCs. The lightly shock-loaded and annealed oligoclase samples have a dominant peak temperature of 120-140 C, identical to type 3.3-3.5 OCs. The heavily shocked samples dominant peak is at 230C, similar to type > 3.5 OCs . While the heavily annealed/disordered oligoclase samples have a peak at 280C, this peak is rarely observed in OCs. Radiation damage from Mrad doses of gamma-rays produced no change in peak temperature, but facilitated the shift to higher peak temperatures. The TL sensitivity of the shocked samples decreased by a factor of 25. Samples annealed at low temperatures (438-533C) showed a factor of 2 decrease in TL, but at the highest temperatures, the TL was a factor of 8 higher

Radiation damage and annealing in plutonium tetrafluoride

Science.gov (United States)

McCoy, Kaylyn; Casella, Amanda; Sinkov, Sergey; Sweet, Lucas; McNamara, Bruce; Delegard, Calvin; Jevremovic, Tatjana

2017-12-01

A sample of plutonium tetrafluoride that was separated prior to 1966 at the Hanford Site in Washington State was analyzed at the Pacific Northwest National Laboratory (PNNL) in 2015 and 2016. The plutonium tetrafluoride, as received, was an unusual color and considering the age of the plutonium, there were questions about the condition of the material. These questions had to be answered in order to determine the suitability of the material for future use or long-term storage. Therefore, thermogravimetric/differential thermal analysis and X-ray diffraction evaluations were conducted to determine the plutonium's crystal structure, oxide content, and moisture content; these analyses reported that the plutonium was predominately amorphous and tetrafluoride, with an oxide content near ten percent. Freshly fluorinated plutonium tetrafluoride is known to be monoclinic. During the initial thermogravimetric/differential thermal analyses, it was discovered that an exothermic event occurred within the material near 414 °C. X-ray diffraction analyses were conducted on the annealed tetrafluoride. The X-ray diffraction analyses indicated that some degree of recrystallization occurred in conjunction with the 414 °C event. The following commentary describes the series of thermogravimetric/differential thermal and X-ray diffraction analyses that were conducted as part of this investigation at PNNL.

Radiation damage and annealing in plutonium tetrafluoride

Energy Technology Data Exchange (ETDEWEB)

McCoy, Kaylyn; Casella, Amanda; Sinkov, Sergey; Sweet, Lucas; McNamara, Bruce; Delegard, Calvin; Jevremovic, Tatjana

2017-12-01

Plutonium tetrafluoride that was separated prior to 1966 at the Hanford Site in Washington State was analyzed at the Pacific Northwest National Laboratory (PNNL) in 2015 and 2016. The plutonium tetrafluoride, as received, was an off-normal color and considering the age of the plutonium, there were questions about the condition of the material. These questions had to be answered in order to determine the suitability of the material for future use or long-term storage. Therefore, Thermogravimetric/Differential Thermal Analysis and X-ray Diffraction evaluations were conducted to determine the plutonium’s crystal structure, oxide content, and moisture content; these analyses reported that the plutonium was predominately amorphous and tetrafluoride, with an oxide content near ten percent. Freshly fluorinated plutonium tetrafluoride is known to be monoclinic. During the initial Thermogravimetric/Differential Thermal analyses, it was discovered that an exothermic event occurred within the material near 414°C. X-ray Diffraction analyses were conducted on the annealed tetrafluoride. The X-ray Diffraction analyses indicated that some degree of recrystallization occurred in conjunction with the 414°C event. The following commentary describes the series of Thermogravimetric/Differential Thermal and X-ray Diffraction analyses that were conducted as part of this investigation at PNNL, in collaboration with the University of Utah Nuclear Engineering Program.

Radiation damage and annealing in plutonium tetrafluoride

International Nuclear Information System (INIS)

McCoy, Kaylyn; Casella, Amanda; Sinkov, Sergey

2017-01-01

A sample of plutonium tetrafluoride that was separated prior to 1966 at the Hanford Site in Washington State was analyzed at the Pacific Northwest National Laboratory (PNNL) in 2015 and 2016. The plutonium tetrafluoride, as received, was an unusual color and considering the age of the plutonium, there were questions about the condition of the material. These questions had to be answered in order to determine the suitability of the material for future use or long-term storage. Therefore, thermogravimetric/differential thermal analysis and X-ray diffraction evaluations were conducted to determine the plutonium's crystal structure, oxide content, and moisture content; these analyses reported that the plutonium was predominately amorphous and tetrafluoride, with an oxide content near ten percent. Freshly fluorinated plutonium tetrafluoride is known to be monoclinic. And during the initial thermogravimetric/differential thermal analyses, it was discovered that an exothermic event occurred within the material near 414 °C. X-ray diffraction analyses were conducted on the annealed tetrafluoride. The X-ray diffraction analyses indicated that some degree of recrystallization occurred in conjunction with the 414 °C event. This commentary describes the series of thermogravimetric/differential thermal and X-ray diffraction analyses that were conducted as part of this investigation at PNNL.

Radiation Damage in Scintillating Crystals

CERN Document Server

Zhu Ren Yuan

1998-01-01

Crystal Calorimetry in future high energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals, and concludes that the predominant radiation damage effect in crystal scintillators is the radiation induced absorption, or color center formation, not the loss of the scintillation light yield. The importance of maintaining crystal's light response uniformity and the feasibility to build a precision crystal calorimeter under radiation are elaborated. The mechanism of the radiation damage in scintillating crystals is also discussed. While the damage in alkali halides is found to be caused by the oxygen or hydroxyl contamination, it is the structure defects, such as oxygen vacancies, cause damage in oxides. Material analysis methods used to reach these conclusions are presented in details.

Solar radiation and mitochondrial DNA damage

International Nuclear Information System (INIS)

Hill, H.Z.; Locitzer, J.; Nassrin, E.; Ogbonnaya, A.; Hubbard, K.

2003-01-01

The 16.6 kB human mitochondrial DNA contains two homologous 13 base pair direct repeats separated by about 5 kB. During asynchronous mitochondrial DNA replication, the distant repeat sequences are thought to anneal, resulting in the looping out of a portion of the non-template strand which is subsequently deleted as a result of interaction with reactive oxygen species (ROS). A normal daughter and a deleted daughter mitochondrion result from such insults. This deletion has been termed the common deletion as it is the most frequent of the known mitochondrial DNA deletions. The common deletion is present in high frequency in several mitochondrial disorders, accumulates with age in slow turnover tissues and is increased in sun-exposed skin. Berneburg, et al. (Photochem. Photobiol. 66: 271, 1997) induced the common deletion in normal human fibroblasts after repeated exposures to UVA. In this study, the common deletion has been shown to be induced by repeated non-lethal exposures to FS20 sunlamp irradiation. Increases in the common deletion were demonstrated using nested PCR which produced a 303 bp product that was compared to a 324 bp product that required the presence of the undeleted 5 kB region. The cells were exposed to 10 repeated doses ranging from 0.5 (UVB) - 0.24 (UVA) J/sq m to 14.4 (UVB) - 5.8 J/sq m (UVA) measured using a UVX digital radiometer and UVB and UVA detectors respectively. Comparison with the earlier study by Berneberg, et al. suggests that this type of simulated solar damage is considerably more effective in fewer exposures than UVA radiation alone. The common deletion provides a cytoplasmic end-point for ROS damage produced by low dose chronic irradiations and other low level toxic exposures and should prove useful in evaluating cytoplasmic damage produced by ionizing radiation as well

Annealing of radiation damage in 0.1- and 2-ohm-centimeter Silicon solar cells

Science.gov (United States)

Weinberg, I.; Swartz, C. K.

1979-01-01

Isochronal and isothermal annealing studies were conducted on 0.1 and 2 ohm centimeter n(+)/p silicon cells after irradiation by 1 MeV electrons at fluences of 10 to the 14th power, 5 times 10 to the 14th power, and 10 to the 15th power per square centimeter. For the 0.1 ohm centimeter cells, reverse annealing was not observed in the isochronal data. However, reverse annealing was observed between approximately 200 and 325 C in the isochronal data of the 2 ohm centimeter cells. Isothermal annealing of 0.1 ohm centimeter cells at 500 C restored pre-irradiation maximum power P sub max within 20 minutes at fluence = 10 to the 14th power, in 180 minutes at fluence = 5 times 10 to the 14th power and to 92 percent of pre-irradiation P sub max in 180 minutes for fluence = 10 to the 15th power. Annealing at 450 C was found inadequate to restore 0.1 ohm centimeter cell performance within reasonable times for all fluence levels. By comparison, at 450 C, the P sub max of 2 ohm centimeter cells was restored within 45 minutes, for the two highest fluence levels, while for the lowest fluence, restoration was completed within 15 minutes. Spectral response data indicate that, for both resistivities, degradation occurs predominantly in the cells p-type base region.

Effect of Thermal Annealing and Second Harmonic Generation on Bulk Damage Performance of Rapid-Growth KDP Type I Doublers at 1064 nm

International Nuclear Information System (INIS)

Runkel, M; Maricle, S; Torres, R; Auerbach, J; Floyd, R; Hawley-Fedder, R; Burnham, A K

2000-01-01

This paper discusses the results of thermal annealing and in-situ second harmonic generation (SHG) damage tests performed on six rapid growth KDP type 1 doubler crystals at 1064 nm (1 ω) on the Zeus automated damage test facility. Unconditioned (S/1) and conditioned (R/1) damage probability tests were performed before and after thermal annealing, then with and without SHG on six doubler crystals from the NIF-size, rapid growth KDP boule F6. The tests revealed that unannealed, last-grown material from the boule in either prismatic or pyramidal sectors exhibited the highest damage curves. After thermal annealing at 160 C for seven days, the prismatic sector samples increased in performance ranging from 1.6 to 2.4X, while material from the pyramidal sector increased only modestly, ranging from 1.0 to 1.4X. Second harmonic generation decreased the damage fluence by an average of 20 percent for the S/1 tests and 40 percent for R/1 tests. Conversion efficiencies under test conditions were measured to be 20 to 30 percent and compared quite well to predicted behavior, as modeled by LLNL frequency conversion computer codes. The damage probabilities at the 1 ω NIF redline fluence (scaled to 10 ns via t 0.5 ) for S/1 tests for the unannealed samples ranged from 20 percent in one sample to 90-100 percent for the other 5 samples. Thermal annealing reduced the damage probabilities to less than 35 percent for 3 of the poor-performing crystals, while two pyramidal samples remained in the 80 to 90 percent range. Second harmonic generation in the annealed crystal increased the S/1 damage probabilities on all the crystals and ranged from 40 to 100 percent. In contrast, R/1 testing of an unannealed crystal resulted in a damage probability at the NIF redline fluence of 16%. Annealing increased the damage performance to the extent that all test sites survived NIF redline fluences without damage. Second harmonic generation in the R/1 test yielded a damage probability of less than 2

Radiation damage to mushrooms

International Nuclear Information System (INIS)

Sattler, P.W.

1986-01-01

This document contains newspaper cuttings and correspondence with various ministries in Hessen on the subject of radiation damage to mushrooms from the Odenwald area. The reader is given, amongst other things, detailed information on radiation damage to different types of mushroom in 1986. (MG) [de

Electric field effects on radiation defects annealing in p-InP

International Nuclear Information System (INIS)

Sibille, A.

1983-01-01

Annealing experiments have been performed on electron irradiated Schottky diodes on p-InP. They show a strong influence of the applied reverse bias during annealing on the recovery of the free holes concentration, as well as on the disappearance of the dominant radiation induced hole traps detected by deep level transient spectroscopy (DLTS). Compensating defects are observed to drift under the action of the electric field and accumulate at the edge of the depleted zone, while the main hole traps created by the irradiation anneal faster when empty of holes or subjected to an electric field. (author)

Thermal annealing response following irradiation of a CMOS imager for the JUICE JANUS instrument

Science.gov (United States)

Lofthouse-Smith, D.-D.; Soman, M. R.; Allanwood, E. A. H.; Stefanov, K. D.; Holland, A. D.; Leese, M.; Turne, P.

2018-03-01

ESA's JUICE (JUpiter ICy moon Explorer) spacecraft is an L-class mission destined for the Jovian system in 2030. Its primary goals are to investigate the conditions for planetary formation and the emergence of life, and how does the solar system work. The JANUS camera, an instrument on JUICE, uses a 4T back illuminated CMOS image sensor, the CIS115 designed by Teledyne e2v. JANUS imager test campaigns are studying the CIS115 following exposure to gammas, protons, electrons and heavy ions, simulating the harsh radiation environment present in the Jovian system. The degradation of 4T CMOS device performance following proton fluences is being studied, as well as the effectiveness of thermal annealing to reverse radiation damage. One key parameter for the JANUS mission is the Dark current of the CIS115, which has been shown to degrade in previous radiation campaigns. A thermal anneal of the CIS115 has been used to accelerate any annealing following the irradiation as well as to study the evolution of any performance characteristics. CIS115s have been irradiated to double the expected End of Life (EOL) levels for displacement damage radiation (2×1010 protons, 10 MeV equivalent). Following this, devices have undergone a thermal anneal cycle at 100oC for 168 hours to reveal the extent to which CIS115 recovers pre-irradiation performance. Dark current activation energy analysis following proton fluence gives information on trap species present in the device and how effective anneal is at removing these trap species. Thermal anneal shows no quantifiable change in the activation energy of the dark current following irradiation.

Influence of post-radiation, accelerate annealing and discreteness on the TID parameters of memerizer

International Nuclear Information System (INIS)

Wang Qunyong; Liu Yanfang; Chen Yu; Jiang Dayong; Bai Ye; Song Yan

2010-01-01

By the study of post-radiation and accelerate annealing in the total ionizing dose (TID), we find out that the additional 50% dose radiation and high temperature accelerate annealing (100 degree C 168 h) can not be skipped in the test because it is necessary to strictly check the memory's TID effect in the space radiation environment. The analysis of device's discreteness in the test shows that parameters of device should be tested before the radiation to get their standard deviation. The high reliability of the memorizer which used in the satellite can be ensured by rejecting the device which increases the standard deviation. The TID test in the NASA report have been confirmed that the effectiveness of parameter test in 'read-only', 'write' and 'erase' mode is better than the test in 'only read' mode as it can reflect the degradation characteristics of the memorizer following ionizing radiation more reasonable. The test sequence applied for each memory at any electrical measurement steps after exposures annealing should be considered. (authors)

Toward understanding dynamic annealing processes in irradiated ceramics

Energy Technology Data Exchange (ETDEWEB)

Myers, Michael Thomas [Texas A & M Univ., College Station, TX (United States)

2013-05-01

High energy particle irradiation inevitably generates defects in solids. The ballistic formation and thermalization of the defect creation process occur rapidly, and are believed to be reasonably well understood. However, knowledge of the evolution of defects after damage cascade thermalization, referred to as dynamic annealing, is quite limited. Unraveling the mechanisms associated with dynamic annealing is crucial since such processes play an important role in the formation of stable postirradiation disorder in ion-beam-processing of semiconductors, and determines the “radiation tolerance” of many nuclear materials. The purpose of this dissertation is to further our understanding of the processes involved in dynamic annealing. In order to achieve this, two main tasks are undertaken.

Radiation damage in lithium-counterdoped N/P silicon solar cells

Science.gov (United States)

Hermann, A. M.; Swartz, C. K.; Brandhorst, H. W., Jr.; Weinberg, I.

1980-01-01

The radiation resistance and low-temperature annealing properties of lithium-counterdoped n(+)-p silicon solar cells are investigated. Cells fabricated from float zone and Czochralski grown silicon were irradiated with 1 MeV electrons and their performance compared to that of 0.35 ohm-cm control cells. The float zone cells demonstrated superior radiation resistance compared to the control cells, while no improvement was noted for the Czochralski grown cells. Annealing kinetics were found to lie between first and second order for relatively short times, and the most likely annealing mechanism was found to be the diffusion of lithium to defects with the subsequent neutralization of defects by combination with lithium. Cells with zero lithium gradients exhibited the best radiation resistance.

Radiation annealing in Ag and Au due to energetic displacement cascades

International Nuclear Information System (INIS)

Averback, R.S.; Merkle, K.L.

1975-01-01

Radiation annealing due to energetic displacement cascades has been studied in Ag and Au. Thin film specimens, 2500 A, were doped to various concentrations of Frenkel pair defects by irradiating with 150 keV protons at temperatures below 10 K. Subsequently, the specimens were irradiated below 10 K with energetic, approximately 540 keV, self-ions. Electrical resistivity measurements were used to monitor the concentration of defects as a function of dose. In Au, approximately 5 percent of the doped-in Frenkel pairs, annealed during the 540 keV Au irradiation. The annealing volume associated with individual cascades was found to be 2.1 x 10 -16 cm 3 . In Ag approximately 5 percent of the doped-in defects annealed during a 500 keV Ag irradiation and the annealing volume of the cascade was found to be 5 x 10 -16 cm 3 . In addition, the effects of doping concentration and specimen temperature during doping were investigated

Radiation-induced liver damage

International Nuclear Information System (INIS)

Marcial, V.A.; Santiago-Delpin, E.A.; Lanaro, A.E.; Castro-Vita, H.; Arroyo, G.; Moscol, J.A.; Gomez, C.; Velazquez, J.; Prado, K.

1977-01-01

Due to the recent increase in the use of radiation therapy in the treatment of cancer with or without chemotherapy, the risk of liver radiation damage has become a significant concern for the radiotherapist when the treated tumour is located in the upper abdomen or lower thorax. Clinically evident radiation liver damage may result in significant mortality, but at times patients recover without sequelae. The dose of 3000 rads in 3 weeks to the entire liver with 5 fractions per week of 200 rads each, seems to be tolerated well clinically by adult humans. Lower doses may lead to damage when used in children, when chemotherapy is added, as in recent hepatectomy cases, and in the presence of pre-existent liver damage. Reduced fractionation may lead to increased damage. Increased fractionation, limitation of the dose delivered to the entire liver, and restriction of the high dose irradiation volume may afford protection. With the aim of studying the problems of hepatic radiation injury in humans, a project of liver irradiation in the dog is being conducted. Mongrel dogs are being conditioned, submitted to pre-irradiation studies (haemogram, blood chemistry, liver scan and biopsy), irradiated under conditions resembling human cancer therapy, and submitted to post-irradiation evaluation of the liver. Twenty-two dogs have been entered in the study but only four qualify for the evaluation of all the study parameters. It has been found that dogs are susceptible to liver irradiation damage similar to humans. The initial mortality has been high mainly due to non-radiation factors which are being kept under control at the present phase of the study. After the initial experiences, the study will involve variations in total dose and fractionation, and the addition of anticoagulant therapy for possible prevention of radiation liver injury. (author)

Characterization of damaging in apatitic materials irradiated with heavy ions and thermally annealed

International Nuclear Information System (INIS)

Tisserand, R.

2004-12-01

Some minerals belonging to the family of apatite are seen to be potential candidates for use as conditioning matrices or transmutation targets for high level nuclear waste management. Indeed, studies of natural nuclear reactors (Oklo) highlighted the strong ability of these minerals to anneal irradiation damage. In order to determine the global behaviour of these materials, we performed a fundamental study on the evolution of irradiation damage induced by various heavy ions in two apatites: a natural phospho-calcic fluor-apatite from Durango and a synthetic sintered mono-silicated fluor-apatite, called britholite. The damage in these materials was measured by using channelling R.B.S. and X-ray diffraction respectively and by determining an amorphization effective radius Re. The results revealed a similar behaviour for both apatites according to the electronic energy deposit at the entrance of the material. In addition, the effect of an isothermal annealing at 300 C was quantified on a mono-silicated britholite previously irradiated with Kr ions. We highlighted in this case the return of the lattice parameters to their initial values, followed by a partial and slow rebuilding of the crystalline lattice versus the annealing time. Finally, we followed the changes in the morphology of etch pits in the Durango fluor-apatite after acid dissolution as a function of the energy deposit by the ions. We showed that the influence of crystallography leads quickly to opening angles close to 30 degrees. The calculation of etching velocities within the irradiated material highlighted that there is a range of deposit energy where the velocity ratio increases strongly before becoming constant. (author)

New technique for global solar radiation forecasting by simulated annealing and genetic algorithms using

International Nuclear Information System (INIS)

Tolabi, H.B.; Ayob, S.M.

2014-01-01

In this paper, a novel approach based on simulated annealing algorithm as a meta-heuristic method is implemented in MATLAB software to estimate the monthly average daily global solar radiation on a horizontal surface for six different climate cities of Iran. A search method based on genetic algorithm is applied to accelerate problem solving. Results show that simulated annealing based on genetic algorithm search is a suitable method to find the global solar radiation. (author)

Effects of impurities on radiation damage in InP

International Nuclear Information System (INIS)

Yamaguchi, M.; Ando, K.

1986-01-01

Strong impurity effects upon introduction and annealing behavior of radiation-induced defects in InP irradiated with 1-MeV electrons have been found. The main defect center of 0.37-eV hole trap H4 in p-InP, which must be due to a point defect, is annealed even at room temperature. Its annealing rate is found to be proportional to the 2/3 power of the preirradiation carrier concentration in InP. Moreover, the density of the hole trap H5 (E/sub v/+0.52 eV) in p-InP, which must be due to a point defect--impurity complex, increases with increase in the InP carrier concentration. These results suggest that the radiation-induced defects in InP must recover through long-range diffusion mediated by impurity atoms. A model is proposed in which point defects diffuse to sinks through impurities so as to disappear or bind impurities so as to form point defect--impurity complexes. In addition to the long-range diffusion mechanism, the possibility of charge-state effects responsible for the thermal annealing of radiation-induced defects in InP is also discussed

Radiation-induced damage of membranes

International Nuclear Information System (INIS)

Yonei, Shuji

1977-01-01

An outline of membranous structure was stated, and radiation-induced damage of membranes were surveyed. By irradiation, permeability of membranes, especially passive transportation mechanism, was damaged, and glycoprotein in the surface layers of cells and the surface layer structures were changed. The intramembranous damage was induced by decrease of electrophoresis of nuclear mambranes and a quantitative change of cytochrome P450 of microsomal membranes of the liver, and peroxidation of membranous lipid and SH substitute damage of membranous protein were mentioned as the mechanism of membranous damage. Recovery of membranous damage depends on radiation dose and temperature, and membranous damage participates largely in proliferation death. (tsunoda, M.)

Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

Science.gov (United States)

Pool, Vanessa L.; Dou, Benjia; Van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

2017-01-01

Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 °C, can be significantly reduced to 40 s at 170 °C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2. PMID:28094249

Empirical constraints on the effects of radiation damage on helium diffusion in zircon

Science.gov (United States)

Anderson, Alyssa J.; Hodges, Kip V.; van Soest, Matthijs C.

2017-12-01

In this study, we empirically evaluate the impact of radiation damage on zircon (U-Th)/He closure temperatures for a suite of zircon crystals from the slowly cooled McClure Mountain syenite of south-central Colorado, USA. We present new zircon, titanite, and apatite conventional (U-Th)/He dates, zircon laser ablation (U-Th)/He and U-Pb dates, and zircon Raman spectra for crystals from the syenite. Titanite and apatite (U-Th)/He dates range from 447 to 523 Ma and 88.0 to 138.9 Ma, respectively, and display no clear correlation between (U-Th)/He date and effective uranium concentration. Conventional zircon (U-Th)/He dates range from 230.3 to 474 Ma, while laser ablation zircon (U-Th)/He dates show even greater dispersion, ranging from 5.31 to 520 Ma. Dates from both zircon (U-Th)/He datasets decrease with increasing alpha dose, indicating that most of the dispersion can be attributed to radiation damage. Alpha dose values for the dated zircon crystals range from effectively zero to 2.15 × 1019 α /g, spanning the complete damage spectrum. We use an independently constrained thermal model to empirically assign a closure temperature to each dated zircon grain. If we assume that this thermal model is robust, the zircon radiation damage accumulation and annealing model of Guenthner et al. (2013) does not accurately predict closure temperatures for many of the analyzed zircon crystals. Raman maps of the zircons dated by laser ablation document complex radiation damage zoning, sometimes revealing crystalline zones in grains with alpha dose values suggestive of amorphous material. Such zoning likely resulted in heterogeneous intra-crystalline helium diffusion and may help explain some of the discrepancies between our empirical findings and the Guenthner et al. (2013) model predictions. Because U-Th zoning is a common feature in zircon, radiation damage zoning is likely to be a concern for most ancient, slowly cooled zircon (U-Th)/He datasets. Whenever possible, multiple

Influence of annealing on X-ray radiation sensing properties of TiO2 thin film

Science.gov (United States)

Sarma, M. P.; Kalita, J. M.; Wary, G.

2018-03-01

A recent study shows that the titanium dioxide (TiO2) thin film synthesised by a chemical bath deposition technique is a very useful material for the X-ray radiation sensor. In this work, we reported the influence of annealing on the X-ray radiation detection sensitivity of the TiO2 film. The films were annealed at 333 K, 363 K, 393 K, 473 K, and 573 K for 1 hour. Structural analyses showed that the microstrain and dislocation density decreased whereas the average crystallite size increased with annealing. The band gap of the films also decreased from 3.26 eV to 3.10 eV after annealing. The I-V characteristics record under the dark condition and under the X-ray irradiation showed that the conductivity increased with annealing. The influence of annealing on the detection sensitivity was negligible if the bias voltage applied across the films was low (within 0.2 V‒1.0 V). At higher bias voltage (>1.0 V), the contribution of electrons excited by X-ray became less significant which affected the detection sensitivity.

Studies of radiation damage in silicon sensors and a measurement of the inelastic proton--proton cross-section at 13 TeV

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00360674; Ward, Patricia

This thesis presents studies of radiation damage in silicon sensors for the new ATLAS tracker at the high-luminosity LHC, calibrations of the LHC luminosity scale, and a measurement of the proton--proton inelastic cross-section at 13 TeV~with ATLAS data. The studies of radiation damage are performed by comparing sensor performance before and after irradiation, and include annealing studies. The measured quantities include: leakage current, depletion depth, inter-strip isolation, and charge collection. Surface and bulk damage is studied by comparing the results of sensors irradiated with protons and neutrons. The observed degradation of performance suggests the current sensor design will endure the radiation damage expected over the lifetime of the experiment at the high-luminosity LHC. The luminosity is calibrated for the proton--proton, proton--lead, and lead--lead collisions delivered by the LHC during 2013 and 2015. The absolute luminosity scale is derived with the van der Meer method. The systematic unc...

Controlling RPV embrittlement through wet annealing in support of life attainment and life extension decisions

International Nuclear Information System (INIS)

Krasikov, E. A.

2012-01-01

As a main barrier against radioactivity outlet reactor pressure vessel (RPV) is a key component in terms of Nuclear Power Plant (NPP) safety. Therefore present-day demands in RPV reliability enhance have to be met by all possible actions for RPV in-service embrittlement mitigation. Annealing treatment is known to be the effective measure to restore the RPV metal properties deteriorated by neutron irradiation. Low temperature 'wet' annealing at a maximum coolant temperature which can be obtained using the reactor core or primary circuit pumps, although it cannot be expected to produce complete recovery, is more attractive from the practical point of view especially in cases when the removal of the internals is impossible. As a rule there is no recovery effect up to annealing and irradiation temperature difference of 70 deg. C. It is known, however, that along with radiation embrittlement neutron irradiation may mitigate the radiation damage in metals. Therefore we have tried to test the possibility to use the effect of radiation-induced ductilization in 'wet' annealing technology by means of nuclear heat utilization as heat and neutron irradiation sources at once. In support of the above-mentioned conception the 3-year duration reactor experiment on 15Cr3NiMoV type steel with preliminary irradiation at operating Pressurized Water Reactor (PWR) at 270 deg. C and following extra irradiation (87 h at 330 deg. C) at IR-8 test reactor was fulfilled. In fact, embrittlement was partly suppressed up to value equivalent to 1,5 fold neutron fluence decrease. The degree of recovery in case of radiation enhanced annealing is equal to 27% whereas furnace annealing results in zero effect under existing conditions. Mechanism of the radiation-induced damage mitigation is proposed. It is hoped that 'wet' annealing technology will help provide a better management of the RPV degradation as a factor affecting the lifetime of nuclear power plants which, together with associated

Controlling RPV embrittlement through wet annealing in support of life attainment and life extension decisions

International Nuclear Information System (INIS)

Krasikov, E.A.

2012-01-01

As a main barrier against radioactivity outlet reactor pressure vessel (RPV) is a key component in terms of Nuclear Power Plant (NPP) safety. Therefore present-day demands in RPV reliability enhance have to be met by all possible actions for RPV in-service embrittlement mitigation. Annealing treatment is known to be the effective measure to restore the RPV metal properties deteriorated by neutron irradiation. Low temperature annealing at a maximum coolant temperature which can be obtained using the reactor core or primary circuit pumps, although it cannot be expected to produce complete recovery, is more attractive from the practical point of view especially in cases when the removal of the internals is impossible. As a rule there is no recovery effect up to annealing and irradiation temperature difference of 70 o C. It is known, however, that along with radiation embrittlement neutron irradiation may mitigate the radiation damage in metals. Therefore we have tried to test the possibility to use the effect of radiation-induced ductilization in annealing technology by means of nuclear heat utilization as heat and neutron irradiation sources at once. In support of the above-mentioned conception the 3-year duration reactor experiment on 15Cr3NiMoV type steel with preliminary irradiation at operating Pressurized Water Reactor (PWR) at 270 o C and following extra irradiation (87 h at 330 o C) at IR-8 test reactor was fulfilled. In fact, embrittlement was partly suppressed up to value equivalent to 1,5 fold neutron fluence decrease. The degree of recovery in case of radiation enhanced annealing is equal to 27% whereas furnace annealing results in zero effect under existing conditions. Mechanism of the radiation-induced damage mitigation is proposed. It is hoped that annealing technology will help provide a better management of the RPV degradation as a factor affecting the lifetime of nuclear power plants which, together with associated management methods, will help

Controlling RPV embrittlement through wet annealing in support of life attainment and life extension decisions

Energy Technology Data Exchange (ETDEWEB)

Krasikov, E. A. [National Research Centre Kurchatov Inst., 1, Kurchatov Sq., Moscow, 123182 (Russian Federation)

2012-07-01

As a main barrier against radioactivity outlet reactor pressure vessel (RPV) is a key component in terms of Nuclear Power Plant (NPP) safety. Therefore present-day demands in RPV reliability enhance have to be met by all possible actions for RPV in-service embrittlement mitigation. Annealing treatment is known to be the effective measure to restore the RPV metal properties deteriorated by neutron irradiation. Low temperature 'wet' annealing at a maximum coolant temperature which can be obtained using the reactor core or primary circuit pumps, although it cannot be expected to produce complete recovery, is more attractive from the practical point of view especially in cases when the removal of the internals is impossible. As a rule there is no recovery effect up to annealing and irradiation temperature difference of 70 deg. C. It is known, however, that along with radiation embrittlement neutron irradiation may mitigate the radiation damage in metals. Therefore we have tried to test the possibility to use the effect of radiation-induced ductilization in 'wet' annealing technology by means of nuclear heat utilization as heat and neutron irradiation sources at once. In support of the above-mentioned conception the 3-year duration reactor experiment on 15Cr3NiMoV type steel with preliminary irradiation at operating Pressurized Water Reactor (PWR) at 270 deg. C and following extra irradiation (87 h at 330 deg. C) at IR-8 test reactor was fulfilled. In fact, embrittlement was partly suppressed up to value equivalent to 1,5 fold neutron fluence decrease. The degree of recovery in case of radiation enhanced annealing is equal to 27% whereas furnace annealing results in zero effect under existing conditions. Mechanism of the radiation-induced damage mitigation is proposed. It is hoped that 'wet' annealing technology will help provide a better management of the RPV degradation as a factor affecting the lifetime of nuclear power plants which

Damage annealing in low temperature Fe/Mn implanted ZnO

International Nuclear Information System (INIS)

Gunnlaugsson, H. P.; Bharuth-Ram, K.; Johnston, K.; Langouche, G.; Mantovan, R.; Mølholt, T. E.; Naidoo, D.; Ólafsson, O.; Weyer, G.

2015-01-01

57 Fe Emission Mössbauer spectra obtained after low fluence (<10 12 cm −2 ) implantation of 57 Mn (T 1/2 = 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe 2+ and Fe 3+ on Zn sites, interstitial Fe and Fe in damage regions (Fe D ). The Fe D component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (∼10 15 cm −2 ) 57 Fe/ 57 Co implanted ZnO and 57 Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT

Material properties of Bohunice 1 and 2 reactor pressure vessel materials before and after annealing

International Nuclear Information System (INIS)

Brumovsky, M.; Novosad, P.; Vacek, M.

1994-01-01

Six types of experimental RPV materials were studied before and after irradiation in host nuclear power and research reactors. Recovery of RPV materials from radiation hardening and embrittlement after annealing was evaluated including a rate of radiation damage after reirradiation used. (author). 3 refs, 4 figs, 2 tabs

Ion implantation damage annealing in 4H-SiC monitored by scanning spreading resistance microscopy

International Nuclear Information System (INIS)

Suchodolskis, A.; Hallen, A.; Linnarsson, M.K.; Osterman, J.; Karlsson, U.O.

2006-01-01

To obtain a better understanding of the damage annealing process and dopant defect incorporation and activation we have implanted epitaxially grown 4H-SiC layers with high doses of Al + ions. Cross-sections of the samples are investigated by scanning spreading resistance microscopy (SSRM) using a commercial atomic force microscopy (AFM). The defects caused by the implanted ions compensate for the doping and decrease the charge carrier mobility. This causes the resistivity to increase in the as-implanted regions. The calculated profile of implanted ions is in good agreement with the measured ones and shows a skewed Gaussian shape. Implanted samples are annealed up to 400 deg. C. Despite these low annealing temperatures we observe a clear improvement of the sample conductivity in the as-implanted region

Modeling of irradiation embrittlement and annealing/recovery in pressure vessel steels

International Nuclear Information System (INIS)

Lott, R.G.; Freyer, P.D.

1996-01-01

The results of reactor pressure vessel (RPV) annealing studies are interpreted in light of the current understanding of radiation embrittlement phenomena in RPV steels. An extensive RPV irradiation embrittlement and annealing database has been compiled and the data reveal that the majority of annealing studies completed to date have employed test reactor irradiated weldments. Although test reactor and power reactor irradiations result in similar embrittlement trends, subtle differences between these two damage states can become important in the interpretation of annealing results. Microstructural studies of irradiated steels suggest that there are several different irradiation-induced microstructural features that contribute to embrittlement. The amount of annealing recovery and the post-anneal re-embrittlement behavior of a steel are determined by the annealing response of these microstructural defects. The active embrittlement mechanisms are determined largely by the irradiation temperature and the material composition. Interpretation and thorough understanding of annealing results require a model that considers the underlying physical mechanisms of embrittlement. This paper presents a framework for the construction of a physically based mechanistic model of irradiation embrittlement and annealing behavior

Repair of radiation damage in mammalian cells

Energy Technology Data Exchange (ETDEWEB)

Setlow, R.B.

1981-01-01

The responses, such as survival, mutation, and carcinogenesis, of mammalian cells and tissues to radiation are dependent not only on the magnitude of the damage to macromolecular structures - DNA, RNA, protein, and membranes - but on the rates of macromolecular syntheses of cells relative to the half-lives of the damages. Cells possess a number of mechanisms for repairing damage to DNA. If the repair systems are rapid and error free, cells can tolerate much larger doses than if repair is slow or error prone. It is important to understand the effects of radiation and the repair of radiation damage because there exist reasonable amounts of epidemiological data that permits the construction of dose-response curves for humans. The shapes of such curves or the magnitude of the response will depend on repair. Radiation damage is emphasized because: (a) radiation dosimetry, with all its uncertainties for populations, is excellent compared to chemical dosimetry; (b) a number of cancer-prone diseases are known in which there are defects in DNA repair and radiation results in more chromosomal damage in cells from such individuals than in cells from normal individuals; (c) in some cases, specific radiation products in DNA have been correlated with biological effects, and (d) many chemical effects seem to mimic radiation effects. A further reason for emphasizing damage to DNA is the wealth of experimental evidence indicating that damages to DNA can be initiating events in carcinogenesis.

Repair of radiation damage in mammalian cells

International Nuclear Information System (INIS)

Setlow, R.B.

1981-01-01

The responses, such as survival, mutation, and carcinogenesis, of mammalian cells and tissues to radiation are dependent not only on the magnitude of the damage to macromolecular structures - DNA, RNA, protein, and membranes - but on the rates of macromolecular syntheses of cells relative to the half-lives of the damages. Cells possess a number of mechanisms for repairing damage to DNA. If the repair systems are rapid and error free, cells can tolerate much larger doses than if repair is slow or error prone. It is important to understand the effects of radiation and the repair of radiation damage because there exist reasonable amounts of epidemiological data that permits the construction of dose-response curves for humans. The shapes of such curves or the magnitude of the response will depend on repair. Radiation damage is emphasized because: (a) radiation dosimetry, with all its uncertainties for populations, is excellent compared to chemical dosimetry; (b) a number of cancer-prone diseases are known in which there are defects in DNA repair and radiation results in more chromosomal damage in cells from such individuals than in cells from normal individuals; (c) in some cases, specific radiation products in DNA have been correlated with biological effects, and (d) many chemical effects seem to mimic radiation effects. A further reason for emphasizing damage to DNA is the wealth of experimental evidence indicating that damages to DNA can be initiating events in carcinogenesis

Origin of reverse annealing effect in hydrogen-implanted silicon

Energy Technology Data Exchange (ETDEWEB)

Di, Zengfeng [Los Alamos National Laboratory; Nastasi, Michael A [Los Alamos National Laboratory; Wang, Yongqiang [Los Alamos National Laboratory

2009-01-01

In contradiction to conventional damage annealing, thermally annealed H-implanted Si exhibits an increase in damage or reverse annealing behavior, whose mechanism has remained elusive. On the basis of quantitative high resolution transmission electron microscopy combined with channeling Rutherford backscattering analysis, we conclusively elucidate that the reverse annealing effect is due to the nucleation and growth of hydrogen-induce platelets. Platelets are responsible for an increase in the height and width the channeling damage peak following increased isochronal anneals.

Mitigating radiation damage of single photon detectors for space applications

Energy Technology Data Exchange (ETDEWEB)

Anisimova, Elena; Higgins, Brendon L.; Bourgoin, Jean-Philippe [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); Cranmer, Miles [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); Choi, Eric [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); Magellan Aerospace, Ottawa, ON (Canada); Hudson, Danya; Piche, Louis P.; Scott, Alan [Honeywell Aerospace (formerly COM DEV Ltd.), Ottawa, ON (Canada); Makarov, Vadim [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); University of Waterloo, Department of Electrical and Computer Engineering, Waterloo, ON (Canada); Jennewein, Thomas [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); Canadian Institute for Advanced Research, Quantum Information Science Program, Toronto, ON (Canada)

2017-12-15

Single-photon detectors in space must retain useful performance characteristics despite being bombarded with sub-atomic particles. Mitigating the effects of this space radiation is vital to enabling new space applications which require high-fidelity single-photon detection. To this end, we conducted proton radiation tests of various models of avalanche photodiodes (APDs) and one model of photomultiplier tube potentially suitable for satellite-based quantum communications. The samples were irradiated with 106 MeV protons at doses approximately equivalent to lifetimes of 0.6, 6, 12 and 24 months in a low-Earth polar orbit. Although most detection properties were preserved, including efficiency, timing jitter and afterpulsing probability, all APD samples demonstrated significant increases in dark count rate (DCR) due to radiation-induced damage, many orders of magnitude higher than the 200 counts per second (cps) required for ground-to-satellite quantum communications. We then successfully demonstrated the mitigation of this DCR degradation through the use of deep cooling, to as low as -86 C. This achieved DCR below the required 200 cps over the 24 months orbit duration. DCR was further reduced by thermal annealing at temperatures of +50 to +100 C. (orig.)

Flash lamp annealing of ion implanted boron profiles

International Nuclear Information System (INIS)

Wieser, E.; Syhre, H.; Ruedenauer, F.G.; Steiger, W.

1983-05-01

The diffusion behaviour of ion implanted boron profiles (5x10E15 B/cm 2 , 50keV) in silicon at 800 0 C and 900 0 C has been compared for samples with and without foregoing flahs - lamp annealing of the radiation damage. The observed differences are discussed with respect to mechanisms of diffusion inhibition in the high concentration region. (Author) [de

Computer simulations of radiation damage in protein crystals

International Nuclear Information System (INIS)

Zehnder, M.

2007-03-01

The achievable resolution and the quality of the dataset of an intensity data collection for structure analysis of protein crystals with X-rays is limited among other factors by radiation damage. The aim of this work is to obtain a better quantitative understanding of the radiation damage process in proteins. Since radiation damage is unavoidable it was intended to look for the optimum ratio between elastically scattered intensity and radiation damage. Using a Monte Carlo algorithm physical processes after an inelastic photon interaction are studied. The main radiation damage consists of ionizations of the atoms through the electron cascade following any inelastic photon interaction. Results of the method introduced in this investigation and results of an earlier theoretical studies of the influence of Auger-electron transport in diamond are in a good agreement. The dependence of the radiation damage as a function of the energy of the incident photon was studied by computer-aided simulations. The optimum energy range for diffraction experiments on the protein myoglobin is 10-40 keV. Studies of radiation damage as a function of crystal volume and shape revealed that very small plate or rod shaped crystals suffer less damage than crystals formed like a cube with the same volume. Furthermore the influence of a few heavy atoms in the protein molecule on radiation damage was examined. Already two iron atoms in the unit cell of myoglobin increase radiation damage significantly. (orig.)

Annealing effects on cathodoluminescence of zircon

Science.gov (United States)

Tsuchiya, Y.; Nishido, H.; Noumi, Y.

2011-12-01

U-Pb zircon dating (e. g., SHRIMP) is an important tool to interpret a history of the minerals at a micrometer-scale, where cathodoluminescence (CL) imaging allows us to recognize internal zones and domains with different chemical compositions and structural disorder at high spatial resolution. The CL of zircon is attributed by various types of emission centers, which are extrinsic ones such as REE impurities and intrinsic ones such as structural defects. Metamictization resulted from radiation damage to the lattice by alpha particles from the decay of U and Th mostly causes an effect on the CL features of zircon as a defect center. However, slightly radiation-damaged zircon, which is almost nondetectable by XRD, has not been characterized using CL method. In this study, annealing effects on CL of zircon has been investigated to clarify a recovery process of the damaged lattice at low radiation dose. A single crystal of zircon from Malawi was selected for CL measurements. It contains HfO2: 2.30 w.t %, U: 241 ppm and Th: 177 ppm. Two plate samples perpendicular to c and a axes were prepared for annealing experiments during 12 hours from room temperature to 1400 degree C. Color CL images were captured using a cold-cathode microscope (Luminoscope: Nuclide ELM-3R). CL spectral measurements were conducted using an SEM (JEOL: JSM-5410) combined with a grating monochromator (Oxford: Mono CL2) to measure CL spectra ranging from 300 to 800 nm in 1 nm steps with a temperature controlled stage. The dispersed CL was collected by a photoncounting method using a photomultiplier tube (Hamamatsu: R2228) and converted to digital data. All CL spectra were corrected for the total instrumental response. Spectral analysis reveals an anisotropy of the CL emission bands related to intrinsic defect center in blue region, radiation-induced defect center from 500 to 700 nm, and trivalent Dy impurity center at 480 and 580 nm, but their relative intensities are almost constant. CL on the

A new cryostat for 'in situ' radiation damage studies

International Nuclear Information System (INIS)

Hariharan, Y.; Radhakrishnan, T.S.

1977-01-01

Conventional cryostats to study properties of materials between 4deg K and 300deg K base their designs either on continuous flow or bath type. A new cryostat which incorporates the advantages of both these has been designed and fabricated. This essentially has three chambers isolated from each other by poor thermal links. These are enclosed in a vacuum chamber and the whole assembly is immersed in a 4 He bath. The lowermost chamber is kept in good thermal contact with the bath. The second chamber can be maintained between 4deg K and 77deg K by circulation of cold 4 He vapour. The uppermost chamber can be maintained between 77deg K and 300deg K by circulating cold nitrogen vapours. There is a through axial hole in the centre, through which the sample can be moved up and down by means of a thin walled stainless steel tube. This comes out from the top of the cryostat through a Wilson seal. Thus the specimen can be anchored in any of the three chambers. This cryostat can be used to study the radiation damages caused by α-particles the sample being kept at 4.2deg K. There is provision for isolating the sample from the radiation zone. Isothermal and isochronal annealing of the damage caused can also be studied. Provision for taking out electrical leads from both inside and outside the sample chamber are also there. (auth.)

Damage annealing in low temperature Fe/Mn implanted ZnO

Energy Technology Data Exchange (ETDEWEB)

Gunnlaugsson, H. P. [University of Aarhus, Department of Physics and Astronomy (Denmark); Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Johnston, K. [PH Department, ISOLDE/CERN (Switzerland); Langouche, G. [University of Leuven, Instituut voor Kern-en Stralings fysika (Belgium); Mantovan, R. [Laboratorio MDM, IMM-CNR (Italy); Mølholt, T. E. [University of Iceland, Science Institute (Iceland); Naidoo, D. [University of the Witwatersrand, School of Physics (South Africa); Ólafsson, O. [University of Iceland, Science Institute (Iceland); Weyer, G. [University of Aarhus, Department of Physics and Astronomy (Denmark)

2015-04-15

{sup 57}Fe Emission Mössbauer spectra obtained after low fluence (<10{sup 12} cm {sup −2}) implantation of {sup 57}Mn (T{sub 1/2}= 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe {sup 2+} and Fe {sup 3+} on Zn sites, interstitial Fe and Fe in damage regions (Fe {sub D}). The Fe {sub D} component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (∼10{sup 15} cm {sup −2}){sup 57}Fe/ {sup 57}Co implanted ZnO and {sup 57}Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

Thermodynamics of post-growth annealing of cadmium zinc telluride nuclear radiation detectors

Science.gov (United States)

Adams, Aaron Lee

Nuclear Radiation Detectors are used for detecting, tracking, and identifying radioactive materials which emit high-energy gamma and X-rays. The use of Cadmium Zinc Telluride (CdZnTe) detectors is particularly attractive because of the detector's ability to operate at room temperature and measure the energy spectra of gamma-ray sources with a high resolution, typically less than 1% at 662 keV. While CdZnTe detectors are acceptable imperfections in the crystals limit their full market potential. One of the major imperfections are Tellurium inclusions generated during the crystal growth process by the retrograde solubility of Tellurium and Tellurium-rich melt trapped at the growth interface. Tellurium inclusions trap charge carriers generated by gamma and X-ray photons and thus reduce the portion of generated charge carriers that reach the electrodes for collection and conversion into a readable signal which is representative of the ionizing radiation's energy and intensity. One approach in resolving this problem is post-growth annealing which has the potential of removing the Tellurium inclusions and associated impurities. The goal of this project is to use experimental techniques to study the thermodynamics of Tellurium inclusion migration in post-growth annealing of CdZnTe nuclear detectors with the temperature gradient zone migration (TGZM) technique. Systematic experiments will be carried out to provide adequate thermodynamic data that will inform the engineering community of the optimum annealing parameters. Additionally, multivariable correlations that involve the Tellurium diffusion coefficient, annealing parameters, and CdZnTe properties will be analyzed. The experimental approach will involve systematic annealing experiments (in Cd vapor overpressure) on different sizes of CdZnTe crystals at varying temperature gradients ranging from 0 to 60°C/mm (used to migrate the Tellurium inclusion to one side of the crystal), and at annealing temperatures ranging

Radiation damage in barium fluoride detector materials

International Nuclear Information System (INIS)

Levey, P.W.; Kierstead, J.A.; Woody, C.L.

1988-01-01

To develop radiation hard detectors, particularly for high energy physics studies, radiation damage is being studied in BaF 2 , both undoped and doped with La, Ce, Nd, Eu, Gd and Tm. Some dopants reduce radiation damage. In La doped BaF 2 they reduce the unwanted long lifetime luminescence which interferes with the short-lived fluorescence used to detect particles. Radiation induced coloring is being studied with facilities for making optical measurements before, during and after irradiation with 60 C0 gamma rays. Doses of 10 6 rad, or less, create only ionization induced charge transfer effects since lattice atom displacement damage is negligible at these doses. All crystals studied exhibit color center formation, between approximately 200 and 800 nm, during irradiation and color center decay after irradiation. Thus only measurements made during irradiation show the total absorption present in a radiation field. Both undoped and La doped BaF 2 develop damage at minimum detectable levels in the UV---which is important for particle detectors. For particle detector applications these studies must be extended to high dose irradiations with particles energetic enough to cause lattice atom displacement damage. In principle, the reduction in damage provided by dopants could apply to other applications requiring radiation damage resistant materials

Radiation damages in solids and tissues

International Nuclear Information System (INIS)

Cevc, P.; Kogovsek, F.; Kanduser, A.; Peternelj, M.; Skaleric, U.; Funduk, N.

1977-01-01

In submitted research work we have studied radiation damages in ferroelectric crystals and application of ferroelectric crystals. Studying the radiation damages we have introduced new technique of EPR measurements under high hydrostatic pressure, that will enable us to obtain additional data on crystal lattice dynamics. A change of piroelectric coefficient with high radiation doses in dopped TGS has been measured also

The influence of non-equilibrium fluctuations on radiation damage and recovery of metals under irradiation

International Nuclear Information System (INIS)

Dubinko, V.I.; Klepikov, V.F.

2007-01-01

In the conventional theory of radiation damage, it is assumed that the main effect of irradiation is due to formation of Frenkel pairs of vacancies and self-interstitial atoms (SIAs) and their clusters. The difference in absorption of vacancies and SIAs by primary or radiation-induced extended defects (EDs) is thought to be the main reason of microstructural evolution under irradiation. On the other hand, the recovery of radiation damage is thought to be driven exclusively by thermal fluctuations resulting in the vacancy evaporation from voids (void annealing) or dislocations (thermal creep) and in the fluctuation-driven overcoming of obstacles by gliding dislocations (plastic strain). However, these recovery mechanisms can be efficient only at sufficiently high temperatures. At lower irradiation temperatures, the main driving force of the recovery processes may be due to nonequilibrium fluctuations of energy states of the atoms surrounding EDs arising as a result of scattering of radiation-induced excitations of atomic and electronic structure at EDs. In the present paper, the mechanisms of nonequilibrium fluctuations that result in such phenomena as the void shrinkage under irradiation at low temperatures (or high dose rates), irradiation creep and irradiation-induced increase of plasticity under sub-threshold irradiation was considered

Radiation damage in biomolecular systems

CERN Document Server

Fuss, Martina Christina

2012-01-01

Since the discovery of X-rays and radioactivity, ionizing radiations have been widely applied in medicine both for diagnostic and therapeutic purposes. The risks associated with radiation exposure and handling led to the parallel development of the field of radiation protection. Pioneering experiments done by Sanche and co-workers in 2000 showed that low-energy secondary electrons, which are abundantly generated along radiation tracks, are primarily responsible for radiation damage through successive interactions with the molecular constituents of the medium. Apart from ionizing processes, which are usually related to radiation damage, below the ionization level low-energy electrons can induce molecular fragmentation via dissociative processes such as internal excitation and electron attachment. This prompted collaborative projects between different research groups from European countries together with other specialists from Canada,  the USA and Australia. This book summarizes the advances achieved by these...

Field oxide radiation damage measurements in silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Laakso, M [Particle Detector Group, Fermilab, Batavia, IL (United States) Research Inst. for High Energy Physics (SEFT), Helsinki (Finland); Singh, P; Shepard, P F [Dept. of Physics and Astronomy, Univ. Pittsburgh, PA (United States)

1993-04-01

Surface radiation damage in planar processed silicon detectors is caused by radiation generated holes being trapped in the silicon dioxide layers on the detector wafer. We have studied charge trapping in thick (field) oxide layers on detector wafers by irradiating FOXFET biased strip detectors and MOS test capacitors. Special emphasis was put on studying how a negative bias voltage across the oxide during irradiation affects hole trapping. In addition to FOXFET biased detectors, negatively biased field oxide layers may exist on the n-side of double-sided strip detectors with field plate based n-strip separation. The results indicate that charge trapping occurred both close to the Si-SiO[sub 2] interface and in the bulk of the oxide. The charge trapped in the bulk was found to modify the electric field in the oxide in a way that leads to saturation in the amount of charge trapped in the bulk when the flatband/threshold voltage shift equals the voltage applied over the oxide during irradiation. After irradiation only charge trapped close to the interface is annealed by electrons tunneling to the oxide from the n-type bulk. (orig.).

The kinetics of isothermal annealing of gamma-irradiation damage in crystalline barium nitrate

International Nuclear Information System (INIS)

Nair, S.M.K.; Krishnan, M.S.; James, C.

1983-01-01

The annealing of #betta#-irradiation damage in crystalline barium nitrate at different temperatures in the range 370 to 430 deg C is a combination of a first-order process affecting a small portion of the fragments and a second-order process, with a higher energy of activation, governing the behaviour of the remainder approx. 73%. The annealing data have been analysed on the models for simple interstitial vacancy recombination and also as a combination of a first-order and second-order process with an energy of activation of 10.9 and 24.0 kcal mole - 1 respectively. It is considered that the first-order process is the combination of close-correlated pairs of O and NO 2- fragments and the second order process involves the single reaction of random recombination of the fragments throughout the crystal. (author)

Annealing study on radiation-induced defects in 6H-SiC

International Nuclear Information System (INIS)

Pinheiro, M.V.B.; Lingner, T.; Caudepon, F.; Greulich-Weber, S.; Spaeth, J.M.

2004-01-01

We present the results of a systematic isochronal annealing investigation of vacancy-related defects in electron-irradiated n-type 6H-SiC:N. A series of 10 samples cut from a commercial wafer and annealed up to 1200 C after electron-irradiation (1.5 x 10 18 cm -3 ) was characterized with photoluminescence (PL), Magnetic circular dichroism of the absorption (MCDA) and conventional electron paramagnetic resonance (EPR). Apart from less stable triplet-related defects which vanished between 150 C and 300 C, the thermal behavior of three radiation-induced defects was studied: the silicon vacancy (V Si ), the carbon-antisite-carbon-vacancy pair (C Si -V C ) and the D1 center. Their annealing behavior showed that the destruction of the isolated V Si between 750 C and 900 C is followed by the formation of thermally more stable C Si -V C pairs, a result that has been theoretically predicted recently. By further heating the samples the C Si -V C pairs are annealed out between 900 C and 1050 C and were followed by an increase in the D1 center concentration. (orig.)

Corneal Damage from Infrared Radiation

National Research Council Canada - National Science Library

McCally, Russell

2000-01-01

...) laser radiation at 10.6 (micrometer) and Tm: YAG laser radiation at 2.02 (micrometer). Retinal damage from sources with rectangular irradiance distributions was also modeled. Thresholds for CO(2...

Studies on the strategies of minimizing radiation damage

Energy Technology Data Exchange (ETDEWEB)

Chung, Hee Yong; Sohn, Young Sook

1998-04-01

We studied on the strategies of minimizing radiation damage in animal system. To this end we studied following areas of research (1) mechanisms involved in bone marrow damage after total body irradiation, (2) extraction of components that are useful in protecting hematopoietic system from radiation damage, (3) cell therapy approach in restoring the damaged tissue, (4) development of radioprotective chemical reagent, and (5) epidemiological study on the population that had been exposed to radiation.

Studies on the strategies of minimizing radiation damage

International Nuclear Information System (INIS)

Chung, Hee Yong; Sohn, Young Sook

1998-04-01

We studied on the strategies of minimizing radiation damage in animal system. To this end we studied following areas of research 1) mechanisms involved in bone marrow damage after total body irradiation, 2) extraction of components that are useful in protecting hematopoietic system from radiation damage, 3) cell therapy approach in restoring the damaged tissue, 4) development of radioprotective chemical reagent, and 5) epidemiological study on the population that had been exposed to radiation

Programmed cellular response to ionizing radiation damage

International Nuclear Information System (INIS)

Crompton, N.E.A.

1998-01-01

Three forms of radiation response were investigated to evaluate the hypothesis that cellular radiation response is the result of active molecular signaling and not simply a passive physicochemical process. The decision whether or not a cell should respond to radiation-induced damage either by induction of rescue systems, e.g. mobilization of repair proteins, or induction of suicide mechanisms, e.g. programmed cell death, appears to be the expression of intricate cellular biochemistry. A cell must recognize damage in its genetic material and then activate the appropriate responses. Cell type is important; the response of a fibroblast to radiation damage is both quantitatively and qualitatively different form that of a lymphocyte. The programmed component of radiation response is significant in radiation oncology and predicted to create unique opportunities for enhanced treatment success. (orig.)

Nature of radiation damage in ceramics

International Nuclear Information System (INIS)

Bunch, J.M.

1976-01-01

Efforts to determine the equivalence between different sources of radiation damage in ceramics are reviewed. The ways in which ceramics differ from metals are examined and proposed mechanisms for creation and stabilization of defects in insulators are outlined. Work on radiation damage in crystalline oxides is summarized and suggestions for further research are offered

Influence of radiation damage evolution on hyperfine interactions of implanted impurities: 169Tm and 175Lu in Fe

International Nuclear Information System (INIS)

Thome, L.; Bernas, H.; Meunier, R.

1978-01-01

The hyperfine interaction of 169 Tm and 175 Lu implanted in Fe and annealed, or implanted at high temperatures, was studied by time-integral and time-differential perturbed angular correlation experiments. The heat treatment was performed in order to modify the impurity-radiation damage interaction in the sample. Comparison of our results with other hyperfine interaction results on rare earths implanted in iron shows that after room-temperature implantation, all the implanted nuclei experience the same hyperfine interaction. The annealing-and implantation-temperature dependences of the fraction of nuclei experiencing this hyperfine interaction are significantly different. The results are interpreted in terms of precipitation of an increasing proportion of implanted impurities. A discussion of their relation to the implanted impurity lattice location is presented in a companion paper

Mechanisms for radiation damage in DNA

International Nuclear Information System (INIS)

Sevilla, M.D.

1993-12-01

In this project the author has proposed several mechanisms for radiation damage to DNA and its constituents, and has detailed a series of experiments utilizing electron spin resonance spectroscopy, HPLC, GC-mass spectroscopy and ab initio molecular orbital calculations to test the proposed mechanisms. In this years work he has completed several experiments on the role of hydration water on DNA radiation damage, continued the investigation of the localization of the initial charges and their reactions on DNA, investigated protonation reactions in DNA base anions, and employed ab initio molecular orbital theory to gain insight into the initial events of radiation damage to DNA. Ab initio calculations have provided an understanding of the energetics evolved in anion and cation formation, ion radical transfer in DNA as well as proton transfer with DNA base pair radical ions. This has been extended in this years work to a consideration of ionization energies of various components of the DNA deoxyribose backbone and resulting neutral sugar radicals. This information has aided the formation of new radiation models for the effect of radiation on DNA. During this fiscal year four articles have been published, four are in press, one is submitted and several more are in preparation. Four papers have been presented at scientific meetings. This years effort will include another review article on the open-quotes Electron Spin Resonance of Radiation Damage to DNAclose quotes

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

International Nuclear Information System (INIS)

Shimada, Masashi; Hara, Masanori; Otsuka, Teppei; Oya, Yasuhisa; Hatano, Yuji

2015-01-01

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 10 26 m −2 ) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min −1 up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

Science.gov (United States)

Shimada, Masashi; Hara, Masanori; Otsuka, Teppei; Oya, Yasuhisa; Hatano, Yuji

2015-08-01

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 1026 m-2) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min-1 up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h.

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, Masashi, E-mail: Masashi.Shimada@inl.gov [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID (United States); Hara, Masanori [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan); Otsuka, Teppei [Kyushu University, Interdisciplinary Graduate School of Engineering Science, Higashi-ku, Fukuoka (Japan); Oya, Yasuhisa [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka (Japan); Hatano, Yuji [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan)

2015-08-15

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 10{sup 26} m{sup −2}) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min{sup −1} up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h.

Radiation damage to nucleoprotein complexes in macromolecular crystallography

International Nuclear Information System (INIS)

Bury, Charles; Garman, Elspeth F.; Ginn, Helen Mary; Ravelli, Raimond B. G.; Carmichael, Ian; Kneale, Geoff; McGeehan, John E.

2015-01-01

Quantitative X-ray induced radiation damage studies employing a model protein–DNA complex revealed a striking partition of damage sites. The DNA component was observed to be far more resistant to specific damage compared with the protein. Significant progress has been made in macromolecular crystallography over recent years in both the understanding and mitigation of X-ray induced radiation damage when collecting diffraction data from crystalline proteins. In contrast, despite the large field that is productively engaged in the study of radiation chemistry of nucleic acids, particularly of DNA, there are currently very few X-ray crystallographic studies on radiation damage mechanisms in nucleic acids. Quantitative comparison of damage to protein and DNA crystals separately is challenging, but many of the issues are circumvented by studying pre-formed biological nucleoprotein complexes where direct comparison of each component can be made under the same controlled conditions. Here a model protein–DNA complex C.Esp1396I is employed to investigate specific damage mechanisms for protein and DNA in a biologically relevant complex over a large dose range (2.07–44.63 MGy). In order to allow a quantitative analysis of radiation damage sites from a complex series of macromolecular diffraction data, a computational method has been developed that is generally applicable to the field. Typical specific damage was observed for both the protein on particular amino acids and for the DNA on, for example, the cleavage of base-sugar N 1 —C and sugar-phosphate C—O bonds. Strikingly the DNA component was determined to be far more resistant to specific damage than the protein for the investigated dose range. At low doses the protein was observed to be susceptible to radiation damage while the DNA was far more resistant, damage only being observed at significantly higher doses

Molecular mechanisms in radiation damage to DNA

International Nuclear Information System (INIS)

Osman, R.

1991-01-01

The objectives of this work are to elucidate the molecular mechanisms that are responsible for radiation-induced DNA damage. The overall goal is to understand the relationship between the chemical and structural changes produced by ionizing radiation in DNA and the resulting impairment of biological function expressed as carcinogenesis or cell death. The studies are based on theoretical explorations of possible mechanisms that link initial radiation damage in the form of base and sugar damage to conformational changes in DNA. These mechanistic explorations should lead to the formulation of testable hypothesis regarding the processes of impairment of regulation of gene expression, alternation in DNA repair, and damage to DNA structure involved in cell death or cancer

Measurement of radiation damage on an optical reflector

International Nuclear Information System (INIS)

Peng, K.C.; Sahu, S.K.; Huang, H.C.; Ueno, K.; Chang, Y.H.; Wang, C.H.; Hou, W.S.

1997-01-01

We measured the radiation damage on an optical white fluorocarbon reflector called Goretex, which is to be used for aerogel threshold counters and crystal calorimeters of the BELLE detector of the KEK B-factory. Reflectance of the Goretex surface was monitored to see any effect of the radiation damage. Maximum equivalent dose was 8.6 Mrad. No radiation damage is observed within measurement errors. (orig.)

Studies of isothermal annealing of fission fragment and alpha particle tracks in Cr-39 polymer detectors

International Nuclear Information System (INIS)

Zaky, M.F.; Youssef, A.A.

2002-01-01

Two groups of CR-39 detectors samples are exposed to two types of charged particle radiation. The first group are severe damaged with fission fragment tracks from 2 52C f source. The second accepted alpha particles resulting from the interaction of highly energetic 1 9F -ions and a copper disk with thickness 1 cm, which are of less damage tracks than fission fragments. , The isothermal annealing of tracks in the temperature range from 175 to 300 degree C in step 25 degree C for annealing time of 10,15,20,25 and 30 minutes has been investigated. The changes introduced in the track density and track diameter for two types of irradiation in the detector have been observed and compared between them. The results indicate that the track density and the size of the tracks are considerably changed due to annealing

Semiconductor annealing

International Nuclear Information System (INIS)

Young, J.M.; Scovell, P.D.

1982-01-01

A process for annealing crystal damage in ion implanted semiconductor devices in which the device is rapidly heated to a temperature between 450 and 900 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. (author)

Radiation Damage in Reactor Materials. Part of the Proceedings of the Symposium on Radiation Damage in Solids and Reactor Materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1963-08-15

Radiation damage has presented a new design parameter for the selection of materials to be used in fuel and cladding elements, moderators, structural components and pressure vessels in nuclear reactors. The severe and novel requirements for certain optimum combinations of physical and nuclear properties have emphasized the need for a better understanding of the basic mechanisms of radiation damage. This knowledge is not only essential for progress in the field of nuclear energy, but has direct applications to space technology and semi-conductor research as well. The IAEA, as part of its programme of promoting nuclear technology, therefore convened the Symposium on Radiation Damage in Solids and Reactor Materials, 7-11 May 1962. At the invitation of, and with generous material assistance from, the Government of Italy, the Symposium was held at Venice. The Symposium was primarily concerned with the investigation of the fundamental processes of radiation that underlie the behaviour of metals, alloys and ceramics that are actually useful or potentially useful reactor materials. Two sessions were devoted to studies of irradiation effects on simple metals, as these effects are easiest to interpret. Other topics included general theory, alloys, fissionable and moderator materials and special experimental techniques for radiation damage studies. The properties influenced by irradiation which were of main concern were those of primary importance to the behaviour of solids as reactor materials (e. g. dimensional stability, phase transformation, radiation hardening, fracture, fission-gas escape from uranium and its compounds). Other properties, such as optical, electrical and magnetic properties, and effects on semiconductors, ionic and other non-metallic crystals are also of interest in that these studies can increase our knowledge of the mechanism of radiation damage in solids and provide a tool for investigation into the physics of the solid state by offering a means of

Radiation Damage in Reactor Materials. Part of the Proceedings of the Symposium on Radiation Damage in Solids and Reactor Materials

International Nuclear Information System (INIS)

1963-01-01

Radiation damage has presented a new design parameter for the selection of materials to be used in fuel and cladding elements, moderators, structural components and pressure vessels in nuclear reactors. The severe and novel requirements for certain optimum combinations of physical and nuclear properties have emphasized the need for a better understanding of the basic mechanisms of radiation damage. This knowledge is not only essential for progress in the field of nuclear energy, but has direct applications to space technology and semi-conductor research as well. The IAEA, as part of its programme of promoting nuclear technology, therefore convened the Symposium on Radiation Damage in Solids and Reactor Materials, 7-11 May 1962. At the invitation of, and with generous material assistance from, the Government of Italy, the Symposium was held at Venice. The Symposium was primarily concerned with the investigation of the fundamental processes of radiation that underlie the behaviour of metals, alloys and ceramics that are actually useful or potentially useful reactor materials. Two sessions were devoted to studies of irradiation effects on simple metals, as these effects are easiest to interpret. Other topics included general theory, alloys, fissionable and moderator materials and special experimental techniques for radiation damage studies. The properties influenced by irradiation which were of main concern were those of primary importance to the behaviour of solids as reactor materials (e. g. dimensional stability, phase transformation, radiation hardening, fracture, fission-gas escape from uranium and its compounds). Other properties, such as optical, electrical and magnetic properties, and effects on semiconductors, ionic and other non-metallic crystals are also of interest in that these studies can increase our knowledge of the mechanism of radiation damage in solids and provide a tool for investigation into the physics of the solid state by offering a means of

Radiation damage prediction system using damage function

International Nuclear Information System (INIS)

Tanaka, Yoshihisa; Mori, Seiji

1979-01-01

The irradiation damage analysis system using a damage function was investigated. This irradiation damage analysis system consists of the following three processes, the unfolding of a damage function, the calculation of the neutron flux spectrum of the object of damage analysis and the estimation of irradiation effect of the object of damage analysis. The damage function is calculated by applying the SAND-2 code. The ANISN and DOT3, 5 codes are used to calculate neutron flux. The neutron radiation and the allowable time of reactor operation can be estimated based on these calculations of the damage function and neutron flux. The flow diagram of the process of analyzing irradiation damage by a damage function and the flow diagram of SAND-2 code are presented, and the analytical code for estimating damage, which is determined with a damage function and a neutron spectrum, is explained. The application of the irradiation damage analysis system using a damage function was carried out to the core support structure of a fast breeder reactor for the damage estimation and the uncertainty evaluation. The fundamental analytical conditions and the analytical model for this work are presented, then the irradiation data for SUS304, the initial estimated values of a damage function, the error analysis for a damage function and the analytical results are explained concerning the computation of a damage function for 10% total elongation. Concerning the damage estimation of FBR core support structure, the standard and lower limiting values of damage, the permissible neutron flux and the allowable years of reactor operation are presented and were evaluated. (Nakai, Y.)

Dislocations and radiation damage in {alpha}-uranium; Dislocations et effets des radiations dans l'uranium {alpha}

Energy Technology Data Exchange (ETDEWEB)

Leteurtre, J [Commissariat a l' Energie Atomique, 92 - Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

Dislocations in {alpha}-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in {alpha}-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [French] Ce travail est une etude par microscopie electronique des dislocations induites dans l'uranium {alpha}, soit par deformation plastique, soit par irradiation. Une methode de preparation des lames minces a basse temperature (-110 deg. C) a ete mise au point. Les vecteurs de Burgers des diverses dislocations de macles de ce metal ont ete definis. Les interactions glissements- maclages sont etudiees experimentalement et theoriquement. Des echantillons irradies a divers taux de combustion ont ete examines. Pour expliquer nos resultats micrographiques, et aussi l'ensemble des informations recueillies dans la litterature concernant l'endommagement par irradiation de l'uranium-{alpha}, nous proposons un modele coherent de l'effet des fragments de fission dans ce metal. L'influence des parametres: temperature, densite de dislocations, impuretes est analysee. Le nombre de defauts ponctuels crees par une fission dans du metal

Fundamental Technology Development for Radiation Damage in Nuclear Materials

International Nuclear Information System (INIS)

Kwon, Sang Chul; Kwon, J. H.; Kim, E. S. and others

2005-04-01

This project was performed to achieve technologies for the evaluation of radiation effects at materials irradiated at HANARO and nuclear power plants, to establish measurement equipment and software for the analysis of radiation defects and to set up facilities for the measurements of radiation damage with non-destructive methods. Major targets were 1) establishment of hot laboratories and remote handling facilities/ technologies for the radioactive material tests, 2) irradiation test for the simulation of nuclear power plant environment and measurement/calculation of physical radiation damage, 3) evaluation and analysis of nano-scale radiation damage, 4) evaluation of radiation embrittlement with ultrasonic resonance spectrum measurement and electromagnetic measurement and 5) basic research of radiation embrittlement and radiation damage mechanism. Through the performance of 3 years, preliminary basics were established for the application research to evaluation of irradiated materials of present nuclear power plants and GEN-IV systems. Particularly the results of SANS, PAS and TEM analyses were the first output in Korea. And computer simulations of radiation damage were tried for the first time in Korea. The technologies will be developed for the design of GEN-IV material

Radiation exposure and chromosome damage

International Nuclear Information System (INIS)

Lloyd, D.

1979-01-01

Chromosome damage is discussed as a means of biologically measuring radiation exposure to the body. Human lymphocytes are commonly used for this test since the extent of chromosome damage induced is related to the exposure dose. Several hundred lymphocytes are analysed in metaphase for chromosome damage, particularly dicentrics. The dose estimate is made by comparing the observed dicentric yield against calibration curves, previously produced by in vitro irradiation of blood samples to known doses of different types of radiation. This test is useful when there is doubt that the film badge has recorded a reasonable whole body dose and also when there is an absence of any physical data. A case of deliberate exposure is described where the chromosome damage test estimated an exposure of 152 rads. The life span of cell aberrations is also considered. Regular checks on radiotherapy patients and some accidental overdose cases have shown little reduction in the aberration levels over the first six weeks after which the damage disappears slowly with a half-life of about three years. In conclusion, chromosome studies have been shown to be of value in resolving practical problems in radiological protection. (U.K.)

Metamict state radiation damage in crystalline materials

International Nuclear Information System (INIS)

Haaker, R.F.; Ewing, R.C.

1979-01-01

Metamict minerals provide an excellent basis for the evaluation of long-term radiation damage effects, particularly such changes in physical and chemical properties as microfracturing, hydrothermal alteration, and solubility. This paper summarizes pertinent literature on metamictization and proposes experiments that are critical to the elucidation of structural controls on radiation damage in crystalline phases

Radiation damage and its repair in non-sporulating bacteria

International Nuclear Information System (INIS)

Moseley, B.E.B.

1984-01-01

A review is given of radiation damage and its repair in non-sporulating bacteria. The identification and measurement of radiation damage in the DNA of the bacteria after exposure to ultraviolet radiation and ionizing radiation is described. Measuring the extent of DNA repair and ways of isolating repair mutants are also described. The DNA repair mechanisms for UV-induced damage are discussed including photoreactivation repair, excision repair, post-replication recombination repair and induced error-prone repair. The DNA repair mechanisms for ionizing radiation damage are also discussed including the repair of both single and double-strand breaks. Other aspects discussed include the effects of growth, irradiation medium and recovery medium on survival, DNA repair in humans, the commercial use of UV and ionizing radiations and the future of ionizing irradiation as a food treatment process. (U.K.)

Radiation damage for the spallation target of ADS

International Nuclear Information System (INIS)

Fan Sheng; Ye Yanlin; Xu Chuncheng; Chen Tao; Sobolevsky, N.M.

2000-01-01

By using SHIELD codes system, the authors investigate the radiation damage, such as radiation damage cross section, displacement atom cross section and the rate of displacement atom, gas production cross section, the rate of gas production and the ratio, R, of the helium and displacement production rates in target, container window and spallation neutron source materials as W and Pb induced from intermediate energy proton and neutron incident. And the study of radiation damage in the thick Pb target with long 60 cm, radius 20 cm is presented

The role of Frenkel defect diffusion in dynamic annealing in ion-irradiated Si

Energy Technology Data Exchange (ETDEWEB)

Wallace, J. B.; Aji, L. B. Bayu; Martin, A. A.; Shin, S. J.; Shao, L.; Kucheyev, S. O.

2017-01-06

The formation of stable radiation damage in crystalline solids often proceeds via complex dynamic annealing processes, involving migration and interaction of ballistically-generated point defects. The dominant dynamic annealing processes, however, remain unknown even for crystalline Si. Here, we use a pulsed ion beam method to study defect dynamics in Si bombarded in the temperature range from -20 to 140 °C with 500 keV Ar ions. Results reveal a defect relaxation time constant of ~10–0.2 ms, which decreases monotonically with increasing temperature. The dynamic annealing rate shows an Arrhenius dependence with two well-defined activation energies of 73 ± 5 meV and 420 ± 10 meV, below and above 60 °C, respectively. Rate theory modeling, bench-marked against this data, suggests a crucial role of both vacancy and interstitial diffusion, with the dynamic annealing rate limited by the migration and interaction of vacancies.

Radiation damage in plastic scintillators

International Nuclear Information System (INIS)

Majewski, S.

1990-01-01

Results of radiation damage studies in plastic scintillators are reviewed and critically analyzed from the point of view of applications of plastic scintillators in calorimetric detectors for the SSC. Damage to transmission and to fluorescent yield in different conditions is discussed. New directions in R ampersand D are outlined. Several examples are given of the most recent data on the new scintillating materials made with old and new plastics and fluors, which are exhibiting significantly improved radiation resistance. With a present rate of a vigorous R D programme, the survival limits in the vicinity of 100 MRad seem to be feasible within a couple of years

Radiation-induced effects in MgO single crystal by 200 keV and 1 MeV Ni ion implantation

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Ryohei; Nakai, Yoshihiro; Hamaguchi, Dai [Kyoto Inst. of Tech. (Japan); and others

1997-03-01

MgO(100) single crystals were implanted with 1.0 MeV and 200 keV Ni ions between 10{sup 15} and 10{sup 17} ions/cm{sup 2} at room temperature. Before and after thermal annealing the radiation damage and the lattice location of implanted Ni ions were analyzed by using Rutherford backscattering spectrometry with channeling and optical absorption measurements. For 1.0 MeV Ni ions, the disorder of Mg atoms increased slowly with ion dose near surface region, while it increased sharply and saturated with ion dose from 2x10{sup 16} ions/cm{sup 2} near ion range. The radiation damage was recovered and implanted Ni ions diffused to the whole of crystal and occupied substitutional positions after 1400degC annealing. For 200 keV Ni ions, the disorder of Mg atoms increased with dose near ion range and had a maximum at about 5x10{sup 16} ions/cm{sup 2}. This tendency agrees with the behavior of color centers obtained from optical measurements. For thermal annealing the radiation damage did not change during 500degC annealing, but the aggregate centers appeared after 300degC annealing. (author)

Dislocations and radiation damage in {alpha}-uranium; Dislocations et effets des radiations dans l'uranium {alpha}

Energy Technology Data Exchange (ETDEWEB)

Leteurtre, J. [Commissariat a l' Energie Atomique, 92 - Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

Dislocations in {alpha}-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in {alpha}-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [French] Ce travail est une etude par microscopie electronique des dislocations induites dans l'uranium {alpha}, soit par deformation plastique, soit par irradiation. Une methode de preparation des lames minces a basse temperature (-110 deg. C) a ete mise au point. Les vecteurs de Burgers des diverses dislocations de macles de ce metal ont ete definis. Les interactions glissements- maclages sont etudiees experimentalement et theoriquement. Des echantillons irradies a divers taux de combustion ont ete examines. Pour expliquer nos resultats micrographiques, et aussi l'ensemble des informations recueillies dans la litterature concernant l'endommagement par irradiation de l'uranium-{alpha}, nous proposons un modele coherent de l'effet des fragments de fission dans ce metal. L'influence des parametres: temperature, densite de dislocations, impuretes est analysee. Le nombre de defauts ponctuels crees

[Mechanisms of electromagnetic radiation damaging male reproduction].

Science.gov (United States)

Xue, Lei; Chen, Hao-Yu; Wang, Shui-Ming

2012-08-01

More and more evidence from over 50 years of researches on the effects of electromagnetic radiation on male reproduction show that a certain dose of electromagnetic radiation obviously damages male reproduction, particularly the structure and function of spermatogenic cells. The mechanisms of the injury may be associated with energy dysmetabolism, lipid peroxidation, abnormal expressions of apoptosis-related genes and proteins, and DNA damage.

Study on DNA damages induced by UV radiation

International Nuclear Information System (INIS)

Doan Hong Van; Dinh Ba Tuan; Tran Tuan Anh; Nguyen Thuy Ngan; Ta Bich Thuan; Vo Thi Thuong Lan; Tran Minh Quynh; Nguyen Thi Thom

2015-01-01

DNA damages in Escherichia coli (E. coli) exposed to UV radiation have been investigated. After 30 min of exposure to UV radiation of 5 mJ/cm"2, the growth of E. coli in LB broth medium was about only 10% in compared with non-irradiated one. This results suggested that the UV radiation caused the damages for E. coli genome resulted in reduction in its growth and survival, and those lesions can be somewhat recovered. For both solutions of plasmid DNAs and E. coli cells containing plasmid DNA, this dose also caused the breakage on single and double strands of DNA, shifted the morphology of DNA plasmid from supercoiled to circular and linear forms. The formation of pyrimidine dimers upon UV radiation significantly reduced when the DNA was irradiated in the presence of Ganoderma lucidum extract. Thus, studies on UV-induced DNA damage at molecular level are very essential to determine the UV radiation doses corresponding to the DNA damages, especially for creation and selection of useful radiation-induced mutants, as well as elucidation the protective effects of the specific compounds against UV light. (author)

High LET radiation and mechanism of DNA damage repair

International Nuclear Information System (INIS)

Furusawa, Yoshiya

2004-01-01

Clarifying the mechanism of repair from radiation damage gives most important information on radiation effects on cells. Approximately 10% of biological experiments groups in Heavy Ion Medical Accelerator in Chiba (HIMAC) cooperative research group has performed the subject. They gave a lot of new findings on the mechanism, and solved some open questions. The reason to show the peak of relative biological effectiveness RBE at around 100-200 keV/μm causes miss-repair of DNA damage. Sub-lethal damage generated by high linear energy transfer (LET) radiation can be repaired fully. Potentially lethal damages by high-LET radiation also repaired, but the efficiency decreased with the LET, and so on. (author)

Molecular mechanisms in radiation damage to DNA: Final report

International Nuclear Information System (INIS)

Osman, R.

1996-01-01

The objectives of this work were to elucidate the molecular mechanisms that were responsible for radiation-induced DNA damage. The studies were based on theoretical explorations of possible mechanisms that link initial radiation damage in the form of base and sugar damage to conformational changes in DNA

Radiation induced genetic damage in Aspergillus nidulans

International Nuclear Information System (INIS)

Georgiou, J.T.

1984-01-01

The mechanism by which ionizing radiation induces genetic damage in haploid and diploid conidia of Aspergillus nidulans was investigated. Although the linear dose-response curves obtained following low LET irradiation implied a 'single-hit' action of radiation, high LET radiations were much more efficient than low LET radiations, which suggests the involvement of a multiple target system. It was found that the RBE values for non-disjunction and mitotic crossing-over were very different. Unlike mitotic crossing-over, the RBE values for non-disjunction were much greater than for cell killing. This suggests that non-disjunction is a particularly sensitive genetical endpoint that is brought about by damage to a small, probably non-DNA target. Radiosensitisers were used to study whether radiation acts at the level of the DNA or some other cellular component. The sensitisation to electrons and/or X-rays by oxygen, and two nitroimidazoles (metronidazole and misonidazole) was examined for radiation induced non-disjunction, mitotic crossing-over, gene conversion, point mutation and cell killing. It was found that these compounds sensitised the cells considerably more to genetic damage than to cell killing. (author)

Radiation damage monitoring in the ATLAS pixel detector

International Nuclear Information System (INIS)

Seidel, Sally

2013-01-01

We describe the implementation of radiation damage monitoring using measurement of leakage current in the ATLAS silicon pixel sensors. The dependence of the leakage current upon the integrated luminosity is presented. The measurement of the radiation damage corresponding to an integrated luminosity 5.6 fb −1 is presented along with a comparison to a model. -- Highlights: ► Radiation damage monitoring via silicon leakage current is implemented in the ATLAS (LHC) pixel detector. ► Leakage currents measured are consistent with the Hamburg/Dortmund model. ► This information can be used to validate the ATLAS simulation model.

Mechanisms for radiation damage in DNA

International Nuclear Information System (INIS)

Sevilla, M.D.

1985-07-01

Radiation damage to DNA results from the direct interaction of radiation with DNA where positive ions, electrons and excited states are formed in the DNA, and the indirect effect where radical species formed in the surrounding medium by the radiation attack the DNA. The primary mechanism proposed for radiation damage, by the direct effect, is that positive and negative ions formed within the DNA strand migrate through the stacked DNA bases. The ions can then recombine, react with the DNA bases most likely to react by protonation of the anion and deprotonation or hydroxylation of the cation or transfer out of the DNA chain to the surrounding histone protein. This work as aimed at understanding the possible reactions of the DNA base ion radicals, as well as their initial distribution in the DNA strand. 31 refs

Recovery of the irradiated JFETs by thermal annealing

International Nuclear Information System (INIS)

Assaf, J.

2007-10-01

Study about the recovering of irradiated JFET transistors has been reported. The JFETs were damaged totally or partially by exposition to Gamma ray and neutrons. Electronics noise has used to evaluate the effect of radiation and the recovery. The study focused on the recovery by thermal annealing, where samples have been heated gradually until 140 centigrade degree (410 K). The recovery ratio given by this method was higher than that resulted from the relaxation method (time recovery) carried out in the room temperature (300 K), especially for Gamma irradiated samples.(author)

Radiation damage of structural materials

International Nuclear Information System (INIS)

Koutsky, J.; Kocik, J.

1994-01-01

Maintaining the integrity of nuclear power plants (NPP) is critical in the prevention or control of severe accidents. This monograph deals with both basic groups of structural materials used in the design of light-water nuclear reactors, making the primary safety barriers of NPPs. Emphasis is placed on materials used in VVER-type nuclear reactors: Cr-Mo-V and Cr-Ni-Mo-V steel for reactor pressure vessels (RPV) and Zr-Nb alloys for fuel element cladding. The book is divided into seven main chapters, with the exception of the opening one and the chapter providing phenomenological background for the subject of radiation damage. Chapters 3-6 are devoted to RPV steels and chapters 7-9 to zirconium alloys, analyzing their radiation damage structure, changes of mechanical properties due to neutron irradiation as well as factors influencing the degree of their performance degradation. The recovery of damaged materials is also discussed. Considerable attention is paid to a comparison of VVER-type and western-type light-water materials

Constructive and critical approach of the radiation damage simulation

International Nuclear Information System (INIS)

Becquart, Ch.

2002-11-01

This work deals with the problem of radiation damage in materials for applications in development of fission and nuclear fusion technologies. It is organised in 3 sections. In section 1 are presented the mechanisms of formation and the evolution kinetics of the primary damage. Section 2 is devoted to the study of the sensitivity of the radiation damage at different approximations. Section 3 discusses the contribution of the ab initio calculations to the study of radiation damage and more particularly the point defects in a dilute Fe-Cu ferritic alloy. This work is illustrated by several publications added in each section. (O.M.)

Investigation of annealed and metamict pyrochlore minerals by x-ray absorption spectroscopy

International Nuclear Information System (INIS)

Greegor, R.B.; Lytle, F.W.; Ewing, R.C.; Chakoumakos, B.C.; Lumpkin, G.R.

1984-01-01

Materials of the pyrochlore structure type exhibit a variety of interesting properties including phases capable of acting as hosts for actinides in radioactive wastes. Studies of curium doped gadolinium titanate phases (Gd 2 Ti 2 O 7 ) have been made which showed that the radiation damage ingrowth followed an exponential relationship. For the study reported here a series of synthetic pyrochlores were produced having the titanate phase with the general formula (RE) 2 Ti 2 O 7 , RE = Er, Y 2 , Gd 2 , Dy, La. Additionally a set of metamict (radiation damaged) pyrochlores was examined in both a natural and post temperature annealed state. Experiments were conducted on these samples using the Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) techniques. In summary, these studies show that in pyrochlore structure types the Ti-O cage undergoes changes due to radiation damage. The individual Ti-O bonds become more disordered which leads to a loss of short and long range order and, ultimately, to expansion of the bulk material. 2 refs., 2 figs

Tooth-germ damage by ionizing radiation

International Nuclear Information System (INIS)

Sobkowiak, E.M.; Beetke, E.; Bienengraeber, V.; Held, M.; Kittner, K.H.

1977-01-01

Experiments on animals (four-week-old dogs) were conducted in an investigation made to study the possibility of dose-dependent tooth-germ damage produced by ionizing radiation. The individual doses were 50 R and 200 R, respectively, and they were administered once to three times at weekly intervals. Hyperemia and edemata could be observed on tooth-germ pulps from 150 R onward. Both of these conditions became more acute as the radiation dose increased (from 150 R to 600 R). Possible damage to both the dentin and enamel is pointed out. (author)

Radiation damage to DNA: the effect of LET

Energy Technology Data Exchange (ETDEWEB)

Ward, J F; Milligan, J R [California Univ., San Diego, La Jolla, CA (United States). School of Medicine

1997-03-01

Mechanisms whereby ionizing radiation induced damage are introduced into cellular DNA are discussed. The types of lesions induced are summarized and the rationale is presented which supports the statement that radiation induced singly damaged sites are biologically unimportant. The conclusion that multiply damaged sites are critical is discussed and the mechanisms whereby such lesions are formed are presented. Structures of multiply damaged sites are summarized and problems which they present to cellular repair systems are discussed. Lastly the effects of linear energy transfer on the complexity of multiply damaged sites are surveyed and the consequences of this increased complexity are considered in terms of cell survival and mutation. (author)

Annealing bounds to prevent further Charge Transfer Inefficiency increase of the Chandra X-ray CCDs

Energy Technology Data Exchange (ETDEWEB)

Monmeyran, Corentin, E-mail: comonmey@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Patel, Neil S., E-mail: neilp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Bautz, Mark W., E-mail: mwb@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Grant, Catherine E., E-mail: cgrant@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Prigozhin, Gregory Y., E-mail: gyp@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Agarwal, Anuradha, E-mail: anu@mit.edu [Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Kimerling, Lionel C., E-mail: lckim@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

2016-12-15

After the front-illuminated CCDs on board the X-ray telescope Chandra were damaged by radiation after launch, it was decided to anneal them in an effort to remove the defects introduced by the irradiation. The annealing led to an unexpected increase of the Charge Transfer Inefficiency (CTI). The performance degradation is attributed to point defect interactions in the devices. Specifically, the annealing at 30 °C activated the diffusion of the main interstitial defect in the device, the carbon interstitial, which led to its association with a substitutional impurity, ultimately resulting in a stable and electrically active defect state. Because the formation reaction of this carbon interstitial and substitutional impurity associate is diffusion limited, we recommend a higher upper bound for the annealing temperature and duration of any future CCD anneals, that of −50 °C for one day or −60 °C for a week, to prevent further CTI increase.

Radiation damage analysis by positron annihilation spectroscopy

International Nuclear Information System (INIS)

Siegel, R.W.

1979-01-01

The application of positron annihilation spectroscopy (PAS) to the characterization and study of defects in metals produced by radiation damage is discussed. The physical basis for the positron annihilation techniques (lifetime, Doppler broadening, angular correlation) is introduced and the techniques briefly described. Some examples of the application of PAS to radiation damage analysis are presented with a view toward elucidating the particular advantages of PAS over more traditional defect characterization techniques

DNA Damage Signals and Space Radiation Risk

Science.gov (United States)

Cucinotta, Francis A.

2011-01-01

Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks.

Effect of electron-excitation on radiation damage in ion-irradiated FCC metals

International Nuclear Information System (INIS)

Iwase, Akihiro

1989-06-01

FCC metals (Al, Cu, Ag, Ni) were irradiated with 0.5-1.8 MeV H, He, N and Ar ions, and 84-126 MeV C, F, Si, Cl, Br and I ions at liquid helium temperatures. After the irradiations, thermal annealing experiments were performed up to 300 K. Anomalous reduction of Stage-I recovery was observed in Al and Ni irradiated with high-energy (∼100 MeV) heavy ions. Radiation annealing by 100 MeV I ions was studied in predoped Ni and Cu. The experimental results were analyzed by using a new model which describes the production and radiation annealing of two or more types of defects. The extraordinarily large cross sections for subthreshold recombination of Stage-I defects were obtained in Ni. These results show that in Al and Ni, the energies transferred from the excited electrons to lattice through the electron-lattice interaction contribute to the annihilations of defects during irradiation. (author)

Pathology of radiation induced lung damage

International Nuclear Information System (INIS)

Kawabata, Yoshinori; Murata, Yoshihiko; Ogata, Hideo; Katagiri, Shiro; Sugita, Hironobu; Iwai, Kazuo; Sakurai, Isamu.

1985-01-01

We examined pathological findings of radiation induced lung damage. Twenty-three cases are chosen from our hospital autopsy cases for 9 years, which fulfil strict criteria of radiation lung damage. Lung damage could be classified into 3 groups : 1) interstitial pneumonia type (9 cases), 2) intermediate pneumonia type (8 cases), and 3) alveolar pneumonia type (6 cases), according to the degree of intra-luminal exudation. These classification is well correlated with clinical findings. Pathological alveolar pneumonia type corresponds to symptomatic, radiologic ground glass pneumonic shadow. And pathologic interstitial type corresponds to clinical asymptomatic, radiologic reticulo-nodular shadow. From the clinico-pathological view point these classification is reasonable one. Radiation affects many lung structures and showed characteristic feature of repair. Elastofibrosis of the alveolar wall is observed in every cases, obstructive bronchiolitis are observed in 5 cases, and obstructive bronchiolitis in 9 cases. They are remarkable additional findings. Thickening of the interlobular septum, broncho-vascular connective tissue, and pleural layer are observed in every cases together with vascular lesions. (author)

Study of radiation damage restoration and antimony ions redistribution in Si(1 0 0) and Si(1 1 1) crystals

CERN Document Server

Labbani, R; Chafi, Z

2002-01-01

In this work, we study the radiation damage restoration and antimony ions redistribution into and oriented silicon substrates. The samples are implanted with antimony to a dose of 5x10 sup 1 sup 4 Sb sup + cm sup - sup 2 at 60 keV energy, then annealed under oxygen atmosphere at 900 deg. C, 30 min. The thin layer of SiO sub 2 (which is formed on Si surface by dry oxidation and expected to prevent any loss of Sb sup + dopant during Si recovery) is removed by a 10% HF solution. The specimens are analyzed by H sup + Rutherford Backscattering Spectrometry operating at 0.3 MeV energy in both random and channelling modes. The values of the projected range, R sub p , the standard deviation, DELTA R sub p , and the dose of antimony ions, which are estimated with a simple program, are in agreement with tabulated ones. It is also shown that the surface damage restoration is better for Si(1 0 0) samples than for Si(1 1 1) ones, in other words, the radiation damage is more significant in Si(1 1 1) substrates. Moreover,...

Acoustic emission sensor radiation damage threshold experiment

International Nuclear Information System (INIS)

Beeson, K.M.; Pepper, C.E.

1994-01-01

Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ''false negative or false positive'' indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments

Ballistic self-annealing during ion implantation

International Nuclear Information System (INIS)

Prins, Johan F.

2001-01-01

Ion implantation conditions are considered during which the energy, dissipated in the collision cascades, is low enough to ensure that the defects, which are generated during these collisions, consist primarily of vacancies and interstitial atoms. It is proposed that ballistic self-annealing is possible when the point defect density becomes high enough, provided that none, or very few, of the interstitial atoms escape from the layer being implanted. Under these conditions, the fraction of ballistic atoms, generated within the collision cascades from substitutional sites, decreases with increasing ion dose. Furthermore, the fraction of ballistic atoms, which finally end up within vacancies, increases with increasing vacancy density. Provided the crystal structure does not collapse, a damage threshold should be approached where just as many atoms are knocked out of substitutional sites as the number of ballistic atoms that fall back into vacancies. Under these conditions, the average point defect density should approach saturation. This model is applied to recently published Raman data that have been measured on a 3 MeV He + -ion implanted diamond (Orwa et al 2000 Phys. Rev. B 62 5461). The conclusion is reached that this ballistic self-annealing model describes the latter data better than a model in which it is assumed that the saturation in radiation damage is caused by amorphization of the implanted layer. (author)

Peculiarities of radiation defect formation and annealing in n-Si due to their interaction with each other and defect clusters

International Nuclear Information System (INIS)

Lugakov, P.F.; Lukyanitsa, V.V.

1984-01-01

Rearrangement processes proceeding during annealing (T/sub a/ = 50 to 500 0 C) of radiation defects in 60 Co γ-irradiated (T/sub irr/ 0 C) n-Si crystals (rho = 100 to 600 Ωcm) grown by the vacuum float-zone technique are studied. The temperature dependences of the Hall coefficient are measured. The results obtained are interpreted taking into account the interaction during annealing of vacancy-type defects (E-centres, divacancies) with each other and interstitial radiation defects (C/sub i/-C/sub s/ complexes, interstitial carbon C/sub i/). Phosphorus-two vacancies complexes, stable to T/sub a/ >= 500 0 C, are shown to be formed as a result of rearrangements and interaction of E-centres between themselves. The character of interaction of vacancy defects with interstitial ones is found to change significantly in the presence of defect clusters in the bulk of the crystal which are formed under heat treatment (T = 800 0 C, two hours) of the samples preliminary irradiated with fast neutrons (flux PHI/sub n/ = 1x10 14 to 1x10 16 cm -2 ). The peculiarities of radiation defects annealing observed in this case are explained taking into account the influence of defect clusters on the migration processes of mobile defects. Nature of radiation defects being formed at various stages of annealing is discussed. (author)

Imperfection and radiation damage in protein crystals studied with coherent radiation

Energy Technology Data Exchange (ETDEWEB)

Nave, Colin, E-mail: colin.nave@diamond.ac.uk [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Sutton, Geoff [Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf; Owen, Robin; Rau, Christoph [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Robinson, Ian [University College London, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Stuart, David Ian [Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

2016-01-01

Coherent diffraction observations from polyhedra crystals at cryotemperature are reported. Information is obtained about the lattice strain and the changes with radiation damage. Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage.

Imperfection and radiation damage in protein crystals studied with coherent radiation

International Nuclear Information System (INIS)

Nave, Colin; Sutton, Geoff; Evans, Gwyndaf; Owen, Robin; Rau, Christoph; Robinson, Ian; Stuart, David Ian

2016-01-01

Coherent diffraction observations from polyhedra crystals at cryotemperature are reported. Information is obtained about the lattice strain and the changes with radiation damage. Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage

Rapid thermal annealing of phosphorus implanted silicon

International Nuclear Information System (INIS)

Lee, Y.H.; Pogany, A.; Harrison, H.B.; Williams, J.S.

1985-01-01

Rapid thermal annealing (RTA) of phosphorus-implanted silicon has been investigated by four point probe, Van der Pauw methods and transmission electron microscopy. The results have been compared to furnace annealing. Experiments show that RTA, even at temperatures as low as 605 deg C, results in good electrical properties with little remnant damage and compares favourably with furnace annealing

Radiation Damage Monitoring in the ATLAS Pixel Detector

CERN Document Server

Seidel, S

2013-01-01

We describe the implementation of radiation damage monitoring using measurement of leakage current in the ATLAS silicon pixel sensors. The dependence of the leakage current upon the integrated luminosity is presented. The measurement of the radiation damage corresponding to integrated luminosity 5.6 fb$^{-1}$ is presented along with a comparison to the theoretical model.

Experimental studies on radiation damages of CsI(Tl) crystals

International Nuclear Information System (INIS)

He Jingtang; Mao Yufang; Dong Xiaoli; Chen Duanbao; Li Zuhao

1997-01-01

The results of experimental studies on radiation damage of CsI(Tl) crystal were reported. There are radiation damage effects on CsI(Tl) crystal. Experimental studies on recovery of damaged CsI(Tl) crystals were made. It seems that after heating at 200 degree C for 4 hours, the damaged crystals could be recovered completely

Molecular mechanisms in radiation damage to DNA. Progress report

International Nuclear Information System (INIS)

Osman, R.

1994-01-01

The objectives of this work are to elucidate the molecular mechanisms that are responsible for radiation-induced DNA damage. The overall goal is to understand the relationship between the chemical and structural changes produced by ionizing radiation in DNA and the resulting impairment of biological function expressed as carcinogenesis or cell death. The studies are based on theoretical explorations of possible mechanisms that link initial radiation damage in the form of base and sugar damage to conformational changes in DNA. These mechanistic explorations should lead to the formulation of testable hypotheses regarding the processes of impairment of regulation of gene expression, alteration in DNA repair, and damage to DNA structure involved in cell death or cancer

Radiation Damage and Dimensional Changes

International Nuclear Information System (INIS)

El-Barbary, A.A.; Lebda, H.I.; Kamel, M.A.

2009-01-01

The dimensional changes have been modeled in order to be accommodated in the reactor design. This study has major implications for the interpretation of damage in carbon based nuclear fission and fusion plant materials. Radiation damage of graphite leads to self-interstitials and vacancies defects. The aggregation of these defects causes dimensional changes. Vacancies aggregate into lines and disks which heal and contract the basal planes. Interstitials aggregate into interlayer disks which expand the dimension

Radiation damage study in montmorillonites. Application to the high-level nuclear waste disposal in France

International Nuclear Information System (INIS)

Sorieul, St.

2003-11-01

Smectite is a major component of bentonite, a material considered for engineered barriers in high level nuclear wastes repositories (HLNWR). In order to predict the long-term performance of the bentonite, various physical and chemical factors such as, e.g., thermal gradient, redox potential or mechanical stresses are currently considered. By contrast, little is known about radiation effects in smectite, although it might affect the properties of this mineral through cumulative radiation damages produced by ionizing radiations. The present study focuses on radiation damage in montmorillonite considered herein as a simplified model of bentonite. Two reference clays have been selected, one from Liaoning (China, CHI), containing native radiation-induced defects, and the other (called MX) separated from the MX80 reference bentonite (Wyoming, USA). They are distinguished by layer composition, particularly iron content (1 % and 4 % for CHI and MX, respectively). Radiation effects have been studied by combining X-ray diffraction, Fourier transform infrared spectroscopy, Electron Paramagnetic Resonance (EPR) and Moessbauer spectroscopies. Ionizing irradiation induces two main effects. First, several paramagnetic point defects are identified as trapped holes located on oxygen atoms of the smectite structure. These defects are characterized by different thermal stabilities, according to annealing experiments. Their creation is limited by saturation curve with maximum damage around 100 MGy. The response of the two montmorillonites is different in terms of nature and production of point defects, indicating a role of layer composition and structural precursors. Besides, EPR and Moessbauer results show substantial modifications of the oxidation state of structural iron, which are sample and dose-dependent. Irradiation induces reduction and oxidation of iron in CHI and MX samples, respectively. Moreover, physico-chemical treatments show that intensity of redox effects varies

Temperature dependence of radiation colloidal centers production and annealing in alkali halide crystals

International Nuclear Information System (INIS)

Kristapson, J.Z.; Ozerskii, V.J.

1981-01-01

The investigation results on temperature dependences of production and annealing of radiation colloidal color centers have been reviewed. In order to produce such centers in NaCl, KCl and KBr crystals the doses of 10 2 -10 4 Mrad as well as irradiation temperatures of 300-600 K and post-irradiation heating of up to 800 K were applied. It has been demonstrated that to produce X-centers, it is necessary to have optimal temperature and initial critical dose during both irradiation and post-irradiation heating of crystals. It has been also found that during annealing hole centers produced are different with regard to thermal stability. The possible recombination mechanisms of hole and electron products of radiolysis during post-irradiation heating has been analyzed [ru

Radiation damage of polymers in ultrasonic fields

Energy Technology Data Exchange (ETDEWEB)

Anbalagan, Poornnima

2008-07-01

Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

Radiation damage of polymers in ultrasonic fields

International Nuclear Information System (INIS)

Anbalagan, Poornnima

2008-01-01

Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

Raman study of radiation-damaged zircon under hydrostatic compression

Science.gov (United States)

Nasdala, Lutz; Miletich, Ronald; Ruschel, Katja; Váczi, Tamás

2008-12-01

Pressure-induced changes of Raman band parameters of four natural, gem-quality zircon samples with different degrees of self-irradiation damage, and synthetic ZrSiO4 without radiation damage, have been studied under hydrostatic compression in a diamond anvil cell up to ~10 GPa. Radiation-damaged zircon shows similar up-shifts of internal SiO4 stretching modes at elevated pressures as non-damaged ZrSiO4. Only minor changes of band-widths were observed in all cases. This makes it possible to estimate the degree of radiation damage from the width of the ν3(SiO4) band of zircon inclusions in situ, almost independent from potential “fossilized pressures” or compressive strain acting on the inclusions. An application is the non-destructive analysis of gemstones such as corundum or spinel: broadened Raman bands are a reliable indicator of self-irradiation damage in zircon inclusions, whose presence allows one to exclude artificial color enhancement by high-temperature treatment of the specimen.

Annealing of KDP crystals in vacuum and under pressure

International Nuclear Information System (INIS)

Pritula, I.M.; Kolybayeva, M.I.; Salo, V.I.

1997-01-01

The effect of the high temperature annealing (T an > 230 degrees C) on the absorption spectra and laser damage threshold of KDP crystals was studied in the present paper. The experiments on isotermal annealing were performed under pressure in the atmosphere with specific properties. The composition of the atmosphere was selected to be chose to that of the desorbing gas component determined during annealing in vacuum. The mentioned conditions allowed to conduct annealing in the temperature range of 230 - 280 degrees C without degradation of the sample. The variations in the absorption spectra showed that the effect of the annealing is most strongly revealed in the short - wave region of the spectrum (λ -1 before and k=0.12 cm -1 after annealing) demonstrate that at temperatures ∼ 230 - 280 degrees C the processes ensuring the improvement of the structure quality are stimulated in the volume of the crystals: (a) before the annealing laser damage threshold was 1.5 10 11 W/cm 2 ; (b) after the annealing (t = 280 degrees C) it became 4 10 11 W/cm 2

DNA damage caused by ionizing radiation

International Nuclear Information System (INIS)

Sachs, R.K.; Peili Chen; Hahnfeldt, P.J.; Klatky, L.R.

1992-01-01

A survey is given of continuous-time Markov chain models for ionizing radiation damage to the genome of mammalian cells. In such models, immediate damage induced by the radiation is regarded as a batch-Poisson arrival process of DNA double-strand breaks (DSBs). Enzymatic modification of the immediate damage is modeled as a Markov process similar to those described by the master equation of stochastic chemical kinetics. An illustrative example is the restitution/complete-exchange model. The model postulates that, after being induced by radiation, DSBs subsequently either undergo enzymatically mediated restitution (repair) or participate pairwise in chromosome exchanges. Some of the exchanges make irremediable lesions such as dicentric chromosome aberrations. One may have rapid irradiation followed by enzymatic DSB processing or have prolonged irradiation with both DSB arrival and enzymatic DSB processing continuing throughout the irradiation period. Methods for analyzing the Markov chains include using an approximate model for expected values, the discrete-time Markov chain embedded at transitions, partial differential equations for generating functions, normal perturbation theory, singular perturbation theory with scaling, numerical computations, and certain matrix methods that combine Perron-Frobenius theory with variational estimates. Applications to experimental results on expected values, variances, and statistical distributions of DNA lesions are briefly outlined. Continuous-time Markov chains are the most systematic of those radiation damage models that treat DSB-DSB interactions within the cell nucleus as homogeneous (e.g., ignore diffusion limitations). They contain virtually all other relevant homogeneous models and semiempirical summaries as special cases, limiting cases, or approximations. However, the Markov models do not seem to be well suited for studying spatial dependence of DSB interactions. 51 refs., 5 figs

Radiation-induced normal tissue damage: implications for radiotherapy

International Nuclear Information System (INIS)

Prasanna, Pataje G.

2014-01-01

Radiotherapy is an important treatment modality for many malignancies, either alone or as a part of combined modality treatment. However, despite technological advances in physical treatment delivery, patients suffer adverse effects from radiation therapy due to normal tissue damage. These side effects may be acute, occurring during or within weeks after therapy, or intermediate to late, occurring months to years after therapy. Minimizing normal tissue damage from radiotherapy will allow enhancement of tumor killing and improve tumor control and patients quality of life. Understanding mechanisms through which radiation toxicity develops in normal tissue will facilitate the development of next generation radiation effect modulators. Translation of these agents to the clinic will also require an understanding of the impact of these protectors and mitigators on tumor radiation response. In addition, normal tissues vary in radiobiologically important ways, including organ sensitivity to radiation, cellular turnover rate, and differences in mechanisms of injury manifestation and damage response. Therefore, successful development of radiation modulators may require multiple approaches to address organ/site-specific needs. These may include treatments that modify cellular damage and death processes, inflammation, alteration of normal flora, wound healing, tissue regeneration and others, specifically to counter cancer site-specific adverse effects. Further, an understanding of mechanisms of normal tissue damage will allow development of predictive biomarkers; however harmonization of such assays is critical. This is a necessary step towards patient-specific treatment customization. Examples of important adverse effects of radiotherapy either alone or in conjunction with chemotherapy, and important limitations in the current approaches of using radioprotectors for improving therapeutic outcome will be highlighted. (author)

Double and triple crystal diffraction investigation on ion implanted and electron beam annealed silicon

International Nuclear Information System (INIS)

Servidori, M.; Cembali, F.; Winter, U.; Zaumseil, P.; Richter, H.

1985-01-01

Double (DCD) and triple crystal (TCD) diffractometry was used to investigate radiation damage produced in silicon by silicon bombardment and its evolution after electron beam annealing. The implantation processes were carried out at 60 keV energy and at doses of 0.5, 1, 5, 10, 50, 100, and 200 x 10 13 ions/cm 2 . As to the annealing treatments, an electron gun was used, operating in the ranges 7.5 to 24 W/cm 2 and 2 to 20 seconds. DCD rocking curves were analyzed by means of the dynamical theory of X-ray diffraction. The formalism introduced by Taupin was used to simulate the experimental intensity profiles. From the resulting best fits, the lattice strain vs. depth profiles were obtained, indicating an increase of the damage with dose for the as-implanted samples up to 1 x 10 14 cm -2 dose, whereas amorphous layers are produced for the higher doses. After annealing, lowering of the residual strain was observed to be directly proportional to the implanted dose. In particular, a complete recovery of the damage occurred for the 0.5 and 1 x 10 13 cm -2 samples. The results obtained by the fitting procedure were substantially independent from the power densities and times used during electron beam irradiation. TCD as a very sensitive method to investigate lattice defects after implantation was used to obtain information about the crystallographic perfection of the surface layer. The absence of diffuse scattering indicates that the annealed layers do not contain microdefects within the detection limits. (author)

Measurement of radiation damage on an epoxy-based optical glue

International Nuclear Information System (INIS)

Huang, H.C.; Peng, K.C.; Sahu, S.K.; Ueno, K.; Chang, Y.H.; Wang, C.H.; Hou, W.S.

1997-01-01

We measured the radiation damage on an optical glue called Eccobond-24, which is a candidate for CsI and BGO crystal calorimeters of the BELLE detector of the KEK B-factory. Absorption spectrophotometry in the range 300-800 nm was used to monitor the radiation damage. The maximum equivalent dose was 1.64 Mrad. The glue shows effects of damage, but is acceptable for the radiation level in the above-mentioned experiment. (orig.)

Silicon P.I.N. Junctions used for studies of radiation damage; Etude de l'irradiation aux neutrons rapides du silicium au moyen de jonctions P.I.N

Energy Technology Data Exchange (ETDEWEB)

Lanore, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-06-01

Irradiation of silicon P.I.N. junction has been studied primarily for the purpose of developing a radiation damage dosimeter, but also for the purpose of investigating silicon itself. It is known that the rate of recombination of electrons and holes is a linear function of defects introduced by neutron irradiation. Two methods have been used to measure that rate of recombination: forward characteristic measurements, recovery time measurements. In order to explain how these two parameters depend on recombination rate we have given a theory of the P.I.N. junction. We have also given an idea of the carrier lifetime dependence versus temperature. Annealing effects in the range of 70 to 700 K have also been studied, we found five annealing stages with corresponding activation energies. As an application for these studies, we developed a radiation damage dosimeter with which we made several experiments in facilities such as Naiade or Marias. (author) [French] L'irradiation de structures P.I.N. etait faite dans le but d'etudier principalement la mise au point d'un dosimetre a ''radiation damage'' et aussi pour etudier plus profondement le silicium lui-meme. On sait que le taux de recombinaison electrons-trous est une fonction lineaire du taux de defauts introduits par irradiation aux neutrons. Deux methodes ont ete utilisees pour atteindre ce taux de recombinaison: mesures de la caracteristique directe, mesures du temps de retournement. Pour expliquer de quelle facon ces parametres dependent du taux de recombinaison. Nous avons donne une theorie de la jonction P.I.N. Nous avons aussi donne l'allure des variations du temps de vie des porteurs en fonction de la temperature. Nous avons d'autre part effectue des recuits entre 70 et 700 K, domaine dans lequel nous avons trouve cinq etapes de ''guerison'' avec les energies d'activation correspondantes. En application de ces etudes nous avons mis ou point un dosimetre a ''radiation damage'' avec lequel nous avons effectue des

Radiation-damage recovery in undoped and oxidized Li doped Mg O crystals implanted with lithium ions

Energy Technology Data Exchange (ETDEWEB)

Alves, E. E-mail: ealves@itn.pt; Silva, R.C. da; Pinto, J.V.; Monteiro, T.; Savoini, B.; Caceres, D.; Gonzalez, R.; Chen, Y

2003-05-01

Undoped MgO and oxidized Li-doped MgO single crystals were implanted with 1 x 10{sup 17} Li{sup +}/cm{sup 2} at 175 keV. The Rutherford backscattering spectrometry (RBS)/channeling data obtained after implantation shows that damage was produced throughout the entire range of the implanted ions. Optical absorption measurements indicate that after implantation the most intense band occurs at {approx}5.0 eV, which has been associated with anion vacancies. After annealing at 450 K the intensity of the oxygen-vacancy band decreases monotonically with temperature and completely disappears at 950 K. A broad extinction band centered at {approx}2.14 eV associated with lithium precipitates emerges gradually and anneals out at 1250 K. RBS/channeling shows that recovery of the implantation damage is completed after annealing the oxidized samples at 1250 K.

Radiation damage studies of nuclear structural materials

International Nuclear Information System (INIS)

Barat, P.

2012-01-01

Maximum utilization of fuel in nuclear reactors is one of the important aspects for operating them economically. The main hindrance to achieve this higher burnups of nuclear fuel for the nuclear reactors is the possibility of the failure of the metallic core components during their operation. Thus, the study of the cause of the possibility of failure of these metallic structural materials of nuclear reactors during full power operation due to radiation damage, suffered inside the reactor core, is an important field of studies bearing the basic to industrial scientific views.The variation of the microstructure of the metallic core components of the nuclear reactors due to radiation damage causes enormous variation in the structure and mechanical properties. A firm understanding of this variation of the mechanical properties with the variation of microstructure will serve as a guide for creating new, more radiation-tolerant materials. In our centre we have irradiated structural materials of Indian nuclear reactors by charged particles from accelerator to generate radiation damage and studied the some aspects of the variation of microstructure by X-ray diffraction studies. Results achieved in this regards, will be presented. (author)

Analysis of radiation damaged nanocrystals

International Nuclear Information System (INIS)

Sitek, J.; Dekan, J.; Sedlackova, K.; Sagatova, A.

2014-01-01

Ribbon-shaped specimens of the master alloy were prepared by planar flow casting. The ribbons with nominal composition of (Fe_1_-_xN_x)_8_1Nb_7B_1_2 (x = 0, 0.25, 0.5, 0.75) were about 25 μm thick and 10 mm wide. To achieve nanocrystalline state, the amorphous ribbons were annealed in vacuum at the temperature of 550 grad C for 1 hour. Samples were irradiated by neutrons in nuclear reactor with fluence of 10"1"6 n/cm"2 and 10"1"7 n/cm"2. and by electrons in linear accelerator with dose 1 MGy at the Slovak Medical University. Moessbauer spectra were collected in transmission geometry by a conventional constant-acceleration spectrometer with a "5"7Co(Rh) source. All spectra were measured at room temperature and evaluated by the CONFIT program, which allows simultaneous treatment of crystalline and residual amorphous phase by means of individual lines and distribution of hyperfine components. After summarizing all obtained results, the fluence 10"1"6 n/cm"2 is still not sufficiently high significantly damage amorphous and crystalline structure. This fluence more or less modify the structure than damage. After fluence 10"17"n/cm"2 we observed beginning of the. structural damage. Our results show, that high electron dose also modify the structure of nanocrystaline alloys. In further study of this alloy it would be necessary to find the limit of electron dose under that the alloy is resistant against electron's damage. From point of view Moessbauer spectroscopy the most sensitive parameter is direction of net magnetic moment. (authors)

Monitoring radiation damage in the ATLAS pixel detector

CERN Document Server

Schorlemmer, André Lukas; Quadt, Arnulf; Große-Knetter, Jörn; Rembser, Christoph; Di Girolamo, Beniamino

2014-11-05

Radiation hardness is one of the most important features of the ATLAS pixel detector in order to ensure a good performance and a long lifetime. Monitoring of radiation damage is crucial in order to assess and predict the expected performance of the detector. Key values for the assessment of radiation damage in silicon, such as the depletion voltage and depletion depth in the sensors, are measured on a regular basis during operations. This thesis summarises the monitoring program that is conducted in order to assess the impact of radiation damage and compares it to model predictions. In addition, the physics performance of the ATLAS detector highly depends on the amount of disabled modules in the ATLAS pixel detector. A worrying amount of module failures was observed during run I. Thus it was decided to recover repairable modules during the long shutdown (LS1) by extracting the pixel detector. The impact of the module repairs and module failures on the detector performance is analysed in this thesis.

Enhancement of radiation damage in germinating wheat seeds by hyperthermia

International Nuclear Information System (INIS)

Guo Fangqing; Gu Ruiqi

1994-01-01

Enhancement of X-ray induced radiation damage in germinating wheat seeds by heat treatment (44 degree C or 41 degree C, 20 min) has been investigated. The enhancement effect of heat treatment after irradiation was more significant than that of heat treatment before irradiation at dose range of 4.3-8.6 Gy. It was observed that germinating wheat seeds were very sensitive to heat treatment within 15 min after irradiation, which indicated that the repair of radiation damage was very active and rapid in a short period after irradiation. The repair of radiation damage in interval of fractionated irradiation was severely inhibited by heat treatment. The sensitivity of seeds to heat treatment corresponded with the levels of their repair activities. The more active the repairs of the seeds are, the more sensitive to heat treatment the seeds show. It was assumed that the enhancement of radiation damage by heat treatment in germinating wheat seeds was attributed to the inhibition of radiation damage repair by heat treatment, which is similar to the results of animal experiments

APD Properties and Recovery from Radiation Damage

CERN Document Server

Baccaro, Stefania; Caruso, S; Cavallari, Francesca; Dafinei, Ioan; Diemoz, Marcella; Emeliantchik, Igor; Festinesi, Armando; Longo, Egidio; Montecchi, Marco; Organtini, Giovanni; Rosi, G

1997-01-01

Avalanche photodiodes will be used to detect scintillation light from PWO crystals in the CMS electromagnetic calorimeter. Properties of Hamamatsu APD are reported special attention has been devoted to the study of radiation hardness and room temperature annealing. We found a fast recovery with a time constant of 1.3 days a medium fast recovery with a lifetime of the order of 10 days and indication of a third component with very long time constant of the order of 300 days.

Damage and in-situ annealing during ion implantation

International Nuclear Information System (INIS)

Sadana, D.K.; Washburn, J.; Byrne, P.F.; Cheung, N.W.

1982-11-01

Formation of amorphous (α) layers in Si during ion implantation in the energy range 100 keV-11 MeV and temperature range liquid nitrogen (LN)-100 0 C has been investigated. Cross-sectional transmission electron microscopy (XTEM) shows that buried amorphous layers can be created for both room temperature (RT) and LN temperature implants, with a wider 100 percent amorphous region for the LN cooled case. The relative narrowing of the α layer during RT implantation is attributed to in-situ annealing. Implantation to the same fluence at temperatures above 100 0 C does not produce α layers. To further investigate in situ annealing effects, specimens already containing buried α layers were further irradiated with ion beams in the temperature range RT-400 0 C. It was found that isolated small α zones (less than or equal to 50 diameter) embedded in the crystalline matrix near the two α/c interfaces dissolved into the crystal but the thickness of the 100 percent α layer was not appreciably affected by further implantation at 200 0 C. A model for in situ annealing during implantation is presented

Development of fusion first-wall radiation damage facilities

International Nuclear Information System (INIS)

McElroy, R.J.; Atkins, T.

1986-11-01

The report describes work performed on the development of fusion-reactor first-wall simulation facilities on the Variable Energy Cyclotron, at Harwell, United Kingdom. Two irradiation facilities have been constructed: i) a device for helium and hydrogen filling up to 1000 ppm for post-irradiation mechanical properties studies, and ii) a helium implantation and damage facility for simultaneous injection of helium and radiation damage into a specimen under stress. These facilities are now fully commissioned and are available for investigations of first-wall radiation damage and for intercorrelation of fission- and fusion -reactor materials behaviour. (U.K.)

Early mechanisms in radiation-induced biological damage

International Nuclear Information System (INIS)

Powers, E.L.

1983-01-01

An introduction to the mechanisms of radiation action in biological systems is presented. Several questions about the nature of the radiation damage process are discussed, including recognition of the oxygen effects, dose-response relationships, and the importance of the hydroxyl radical

THE ROLE OF RADIATION ACCIDENTS AND INDUSTRIAL APPLICATIONS OF IONIZING RADIATION SOURCES IN THE PROBLEM OF RADIATION DAMAGE

OpenAIRE

Кіхтенко, Ігор Миколайович

2016-01-01

Subject of research – the relevance of radiation damage at modern development of industry and medicine. In the world of radiation sources used in different fields of practice and their application in the future will increase, which greatly increases the likelihood of injury in a significant contingent of people.Research topic – the definition of the role of nuclear energy and the industrial use of ionizing radiation sources in the problem of radiation damage. The purpose of research – identif...

Current study on ionizing radiation-induced mitochondial DNA damage and mutations

International Nuclear Information System (INIS)

Zhou Xin; Wang Zhenhua; Zhang Hong

2012-01-01

Current advance in ionizing radiation-induced mitochondrial DNA damage and mutations is reviewed, in addition with the essential differences between mtDNA and nDNA damage and mutations. To extent the knowledge about radiation induced mitochondrial alterations, the researchers in Institute of Modern Physics, Chinese Academy of Sciences developed some technics such as real-time PCR, long-PCR for accurate quantification of radiation induced damage and mutations, and in-depth investigation about the functional changes of mitochondria based on mtDNA damage and mutations were also carried out. In conclusion, the important role of mitochondrial study in radiation biology is underlined, and further study on mitochondrial study associated with late effect and metabolism changes in radiation biology is pointed out. (authors)

A simple method to identify radiation and annealing biases that lead to worst-case CMOS static RAM postirradiation response

International Nuclear Information System (INIS)

Fleetwood, D.M.; Dressendorfer, P.V.

1987-01-01

The authors illustrate a simple method to identify bias conditions that lead to worst-case postirradiation speed and timing response for SRAMs. Switching cell states between radiation and anneal should lead to maximum speed and timing degradation for many hardened designs and technologies. The greatest SRAM cell imbalance is also established by these radiation and annealing conditions for the hardened and commercial parts that we have examined. These results should provide insight into the behavior of SRAMs during and after irradiation. The results should also be useful to establishing guidelines for integrated-circuit functionality testing, and SEU and dose-rate upset testing, after total-dose irradiation

State of damage of radiation facilities in great Hanshin earthquake

International Nuclear Information System (INIS)

1995-01-01

The southern Hyogo Prefecture earthquake of magnitude 7.2 occurred in the early morning of January 17, 1995. The outline of the earthquake and dead and injured, the damages of buildings, life lines, roads, railways and harbors, liquefaction phenomena, the state of occurrence of fires and so on are reported. The districts where the earthquakes of magnitude 5 or stronger occurred, and the radiation facilities in those districts are shown. The state of damage of radiation facilities in past earthquakes is summarized. From January 17 to 19 after the earthquake, Science and Technology Agency gave necessary instruction to and heard the state of damage from 79 permitted facilities in the areas of magnitude 7 or 6 by telephone, and received the report that there was not the fear of radiation damage in all facilities. Also the state of damage of radiation facilities was investigated at the actual places, and the questionnaires on the state of radiation facilities and the action at the time of the earthquake were performed. The state of radiation facilities accompanying the earthquake is reported. The matters to be reflected to the countermeasures to earthquakes anew for the protection of facilities, communication system, facility checkup system and the resumption of use are pointed out. (K.I.)

Temperature dependence of the radiation induced change of depletion voltage in silicon PIN detectors

International Nuclear Information System (INIS)

Ziock, H.J.; Holzscheiter, K.; Morgan, A.; Palounek, A.P.T.; Ellison, J.; Heinson, A.P.; Mason, M.; Wimpenny, S.J.; Barberis, E.; Cartiglia, N.; Grillo, A.; O'Shaughnessy, K.; Rahn, J.; Rinaldi, P.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Webster, A.; Wichmann, R.; Wilder, M.; Coupal, D.; Pal, T.

1993-01-01

The silicon microstrip detectors that will be used in the SDC experiment at the Superconducting Super Collider (SSC) will be exposed to very large fluences of charged particles, neutrons, and gammas. The authors present a study of how temperature affects the change in the depletion voltage of silicon PIN detectors damaged by radiation. They study the initial radiation damage and the short-term and long-term annealing of that damage as a function of temperature in the range from -10 degrees C to +50 degrees C, and as a function of 800 MeV proton fluence up to 1.5 x 10 14 p/cm 2 . They express the pronounced temperature dependencies in a simple model in terms of two annealing time constants which depend exponentially on the temperature

Radiation damage in nuclear waste materials

International Nuclear Information System (INIS)

Jencic, I.

2000-01-01

Final disposal of high-level radioactive nuclear waste is usually envisioned in some sort of ceramic material. The physical and chemical properties of host materials for nuclear waste can be altered by internal radiation and consequently their structural integrity can be jeopardized. Assessment of long-term performance of these ceramic materials is therefore vital for a safe and successful disposal. This paper presents an overview of studies on several possible candidate materials for immobilization of fission products and actinides, such as spinel (MgAl 2 O 4 ), perovskite (CaTiO 3 ), zircon (ZrSiO 4 ), and pyrochlore (Gd 2 Ti 2 O 7 and Gd 2 Zr 2 O 7 ). The basic microscopic picture of radiation damage in ceramics consists of atomic displacements and ionization. In many cases these processes result in amorphization (metaminctization) of irradiated material. The evolution of microscopic structure during irradiation leads to various macroscopic radiation effects. The connection between microscopic and macroscopic picture is in most cases at least qualitatively known and studies of radiation induced microscopic changes are therefore an essential step in the design of a reliable nuclear waste host material. The relevance of these technologically important results on our general understanding of radiation damage processes and on current research efforts in Slovenia is also addressed. (author)

Investigation of radiation damage effects in neutron irradiated CCD

International Nuclear Information System (INIS)

Brau, James E.; Igonkina, Olga; Potter, Chris T.; Sinev, Nikolai B.

2005-01-01

A Charge Coupled Devices (CCD)-based vertex detector is a leading option for vertex detection at the future linear collider. A major issue for this application is the radiation hardness of such devices. Tests of radiation hardness of CCDs used in the SLD vertex detector, VXD3, have been reported earlier. The first measurements of 1998 involved a spare VXD3 CCD that was irradiated with neutrons from a radioactive source (Pu-Be), and from a nuclear reactor. In 2003, we had the opportunity to disassemble the VXD3 detector and study the nature of the radiation damage it incurred during 3 years of operation at SLC. In the preparation for this study, additional experiments with the spare VXD3 CCD were performed. These included measurements of trapping times in neutron irradiated CCDs. Results, reported here, will help us better understand the mechanism of radiation damage effects and develop techniques to minimize performance degradation due to radiation damage

Radiation damage to DNA: The importance of track structure

CERN Document Server

Hill, M A

1999-01-01

A wide variety of biological effects are induced by ionizing radiation, from cell death to mutations and carcinogenesis. The biological effectiveness is found to vary not only with the absorbed dose but also with the type of radiation and its energy, i.e., with the nature of radiation tracks. An overview is presented of some of the biological experiments using different qualities of radiation, which when compared with Monte Carlo track structure studies, have highlighted the importance of the localized spatial properties of stochastic energy deposition on the nanometer scale at or near DNA. The track structure leads to clustering of damage which may include DNA breaks, base damage etc., the complexity of the cluster and therefore its biological repairability varying with radiation type. The ability of individual tracks to produce clustered damage, and the subsequent biological response are important in the assessment of the risk associated with low-level human exposure. Recent experiments have also shown that...

Radiation damage in CaF2: Gd

International Nuclear Information System (INIS)

Prado, L.

1979-01-01

Calcium fluoride crystals doped with Gd 3+ at four different concentrations were irradiated at room temperature. The damage produced by radiation and the primary and secondary effects as well were studied by optical spectroscopy. The increase in optical absorption (with loss of transparency) varied from sample as a function of concentration and dose. The coloration curves showed an evolution from two to three radiation damage steps when going from a pure to the most Gd 3+ concentrated sample. The obtained spectra were analysed at characteristic wave lenghts of electronic defects (photochromic centers, F and its aggregates) and of Gd 3+ and Gd 2+ defects. As a result of the radiation damage the valence change (Gd 3+ →Gd 2+ ) and its reversible character under thermal activation were directly observed. These effects were correlated with other observed effects such as the room temperature luminescence after the irradiation ceased. The non radiative F centers formation from the interaction of holes and photochromic centers was also observed and analysed. A thermal activation study of the several defects responsible for the different absorption bands was made. Values of activation energies were obtained as expected for the kind of defects involved in these processes [pt

Radiation damage to DNA: The importance of track structure

International Nuclear Information System (INIS)

Hill, M.A.

1999-01-01

A wide variety of biological effects are induced by ionizing radiation, from cell death to mutations and carcinogenesis. The biological effectiveness is found to vary not only with the absorbed dose but also with the type of radiation and its energy, i.e., with the nature of radiation tracks. An overview is presented of some of the biological experiments using different qualities of radiation, which when compared with Monte Carlo track structure studies, have highlighted the importance of the localized spatial properties of stochastic energy deposition on the nanometer scale at or near DNA. The track structure leads to clustering of damage which may include DNA breaks, base damage etc., the complexity of the cluster and therefore its biological repairability varying with radiation type. The ability of individual tracks to produce clustered damage, and the subsequent biological response are important in the assessment of the risk associated with low-level human exposure. Recent experiments have also shown that biological response to radiation is not always restricted to the 'hit' cell but can sometimes be induced in 'un-hit' cells near by

Radiation damage in DNA

International Nuclear Information System (INIS)

Lafleur, V.

1978-01-01

A number of experiments are described with the purpose to obtain a better insight in the chemical nature and the biological significance of radiation-induced damage in DNA, with some emphasis on the significance of alkali-labile sites. It is shown that not only reactions of OH radicals but also of H radicals introduce breaks and other inactivating damage in single-standed phiX174 DNA. It is found that phosphate buffer is very suitable for the study of the reactions of H radicals with DNA, as the H 2 PO 4 - ions convert the hydrated electrons into H radicals. The hydrated electron, which does react with DNA, does not cause a detectable inactivation. (Auth.)

Ion - biomolecule interactions and radiation damage

International Nuclear Information System (INIS)

Schlathoelter, T.

2004-01-01

Full text: The biological effects of ionizing radiation in living cells are not a mere result of the direct impact of high energy quanta of radiation. Secondary particles such as low energy electrons, radicals and (multiply charged) ions are formed within the track. The interaction of these secondary particles with biologically relevant molecules is responsible for a large fraction of biological radiation damage to a cell, as well. Singly and multiply charged ions can be of importance as both, primary and secondary particles, and are known to cause severe biological damage. For instance, in heavy ion therapy and proton therapy the pronounced Bragg peak of fast (typically a few 100 MeV/u) ions in biological tissue is utilized. The Bragg peak is located at a depth, where the ions (mostly C q+ or protons) are slowed down to about 100 keV/u and have their maximum linear energy transfer (LET) to the medium. This depth is reasonably well defined and depends on the initial ion kinetic energy. Since the ions are rapidly stopped in this energy range, penetration beyond the Bragg peak is weak and it is thus possible to 'scan' the Bragg peak through a malignant tumour without excessive damage of the surrounding tissue by mere variation of the ion kinetic energy (i.e. the penetration depth). Severe biological damage is almost only possible, when the track of a primary quantum of ionizing radiation crosses the nucleus of a cell. Particularly the induction of double strand breaks of DNA or clustered DNA lesions is potentially lethal or mutagenic. A primary particle interacting with individual molecules within this environment leads to molecular excitation, ionization and fragmentation. In the process, the primary particle looses energy and slow secondary electrons and ions are formed, which might induce further damage. For a deep understanding of biological radiation damage on the level of individual molecules it is thus important to quantify excitation, ionization and

Computer simulations of radiation damage in protein crystals; Simulationsrechnungen zu Strahlenschaeden an Proteinkristallen

Energy Technology Data Exchange (ETDEWEB)

Zehnder, M

2007-03-15

The achievable resolution and the quality of the dataset of an intensity data collection for structure analysis of protein crystals with X-rays is limited among other factors by radiation damage. The aim of this work is to obtain a better quantitative understanding of the radiation damage process in proteins. Since radiation damage is unavoidable it was intended to look for the optimum ratio between elastically scattered intensity and radiation damage. Using a Monte Carlo algorithm physical processes after an inelastic photon interaction are studied. The main radiation damage consists of ionizations of the atoms through the electron cascade following any inelastic photon interaction. Results of the method introduced in this investigation and results of an earlier theoretical studies of the influence of Auger-electron transport in diamond are in a good agreement. The dependence of the radiation damage as a function of the energy of the incident photon was studied by computer-aided simulations. The optimum energy range for diffraction experiments on the protein myoglobin is 10-40 keV. Studies of radiation damage as a function of crystal volume and shape revealed that very small plate or rod shaped crystals suffer less damage than crystals formed like a cube with the same volume. Furthermore the influence of a few heavy atoms in the protein molecule on radiation damage was examined. Already two iron atoms in the unit cell of myoglobin increase radiation damage significantly. (orig.)

Spallation radiation damage and the radiation damage facility at the LAMPF A-6 target station

Energy Technology Data Exchange (ETDEWEB)

Wechsler, M.S.; Sommer, W.F. (Los Alamos National Lab., NM (USA))

1984-05-01

A redesign of the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF) A-6 Target Station is underway that will permit materials irradiations to be conducted in the proton beam and in the spallation neutron environment under more controlled conditions than has been possible heretofore. The protons of energy near 800 MeV and beam current approaching one mA are able to produce radiation damage rates (displacement production rates) as high as can be achieved in fission reactors, and the damage is uniform over macroscopic dimensions. The spallation neutrons have a degraded fission spectrum energy distribution, with the important admixture of a high energy tail up to 800 MeV. Irradiations in these radiation environments can be used to address important problems in the development of materials for fusion reactors. The redesign of the A-6 Target Station is described and plans for its use are discussed.

Mechanisms for radiation damage in DNA

International Nuclear Information System (INIS)

Sevilla, M.D.

1987-01-01

Several mechanisms are proposed for radiation damage to DNA and its constituents, and a series of experiments utilizing electron spin resonance spectrometry have been used to test the proposed mechanisms. In the past we have concentrated chiefly on investigating irradiated systems of DNA constituents. In this year's effort we have concentrated on radiation effects on DNA itself. In addition studies of radiation effects on lipids and model compounds have been performed which shed light on the only other proposed site for cell kill, the membrane

Radiation damage in BaF2 crystals

International Nuclear Information System (INIS)

Woody, C.L.; Kierstead, J.A.; Levy, P.W.; Stoll, S.

1991-01-01

The effects of radiation damage and recovery have been studied in BaF 2 crystals exposed to 60 Co radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 x 10 6 rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals whichhave been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shown a peakat ∼330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose

Characterization of radiation damage induced by swift heavy ions in graphite

Energy Technology Data Exchange (ETDEWEB)

Hubert, Christian

2016-05-15

irradiation temperatures above 200 C damage formation is mitigated due to defect annealing. Thus a controlled temperature of accelerator components is desirable in order to increase the lifetime. This thesis contributes to a better understanding of radiation damage in swift heavy ion-exposed graphite with the aim to optimize the design of beam catchers and production targets for secondary ion beams for the Super Fragment Separator (Super-FRS) at FAIR. Moreover, the results of this work provide important input data for simulations to describe the beam response and lifetime of high-dose exposed critical accelerator components.

Radiation damage in non-metals

International Nuclear Information System (INIS)

Stoneham, A.M.

1980-01-01

Work on the problem of radiation damage in non-metals over the past 25 years is reviewed with especial emphasis on the contribution made at AERE, Harwell and in particular by members of the Theoretical Physics Division. In the years between 1954 and the end of the 1960's the main thrust in the radiation damage of non-metals was model-building including devising defect models and mechanisms that were qualitatively acceptable, and compiling systematic data. The early 1970's made greater quantitative demands as computer techniques made theory more powerful. In many cases it was possible to predict defect properties accurately, so that one could distinguish between different defect models which were hard to tell apart by experiment alone. In the late 1970's the most important aspect has moved towards mechanisms of defect processes, especially in cases where experiment by itself is limited by timescale, by complexity, by the unintentional impurities inevitable in real crystals, or by the extreme conditions required. (UK)

A study of proton polarization in ammonia (NH sub 3 ) under irradiation and annealing

Energy Technology Data Exchange (ETDEWEB)

Belyaev, A.A.; Get' man, V.A.; Dzyubak, A.P.; Karnaukhov, I.M.; Lukhanin, A.A.; Neffa, A.Yu.; Semisalov, I.L.; Sorokin, P.V.; Sporov, E.S.; Telegin, Yu.N.; Tolmachev, I.A.; Trotsenko, V.I. (Kharkov Institute of Physics and Technology, Ukrainian SSR, Academy of Sciences, 310108 Kharkov, USSR (UA))

1989-05-05

The proton polarization in irradiated NH{sub 3} has been measured as a function of the irradiation dose and annealing temperature. The analysis of the experimental data obtained shows that under low-temperature'' irradiation along with the NH{sup {minus}}{sub 2} the e{sub tr}-radical is likely to be formed which contributes to the polarization build-up and relaxation and influences the radiation damage resistance of the target.

Ionizing radiation, antioxidant response and oxidative damage: A meta-analysis

Energy Technology Data Exchange (ETDEWEB)

Einor, D., E-mail: daniel@einor.com [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); Bonisoli-Alquati, A., E-mail: andreabonisoli@gmail.com [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, LA 70803 (United States); Costantini, D., E-mail: davidcostantini@libero.it [Department of Biology, University of Antwerp, Wilrijk, B-2610, Antwerp (Belgium); Mousseau, T.A., E-mail: mousseau@sc.edu [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); Faculty of Bioscience and Biotechnology, Chubu University, Kasugai (Japan); Møller, A.P., E-mail: anders.moller@u-psud.fr [Laboratoire d' Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F-91405 Orsay Cedex (France)

2016-04-01

One mechanism proposed as a link between exposure to ionizing radiation and detrimental effects on organisms is oxidative damage. To test this hypothesis, we surveyed the scientific literature on the effects of chronic low-dose ionizing radiation (LDIR) on antioxidant responses and oxidative damage. We found 40 publications and 212 effect sizes for antioxidant responses and 288 effect sizes for effects of oxidative damage. We performed a meta-analysis of signed and unsigned effect sizes. We found large unsigned effects for both categories (0.918 for oxidative damage; 0.973 for antioxidant response). Mean signed effect size weighted by sample size was 0.276 for oxidative damage and − 0.350 for antioxidant defenses, with significant heterogeneity among effects for both categories, implying that ionizing radiation caused small to intermediate increases in oxidative damage and small to intermediate decreases in antioxidant defenses. Our estimates are robust, as shown by very high fail-safe numbers. Species, biological matrix (tissue, blood, sperm) and age predicted the magnitude of effects for oxidative damage as well as antioxidant response. Meta-regression models showed that effect sizes for oxidative damage varied among species and age classes, while effect sizes for antioxidant responses varied among species and biological matrices. Our results are consistent with the description of mechanisms underlying pathological effects of chronic exposure to LDIR. Our results also highlight the importance of resistance to oxidative stress as one possible mechanism associated with variation in species responses to LDIR-contaminated areas. - Highlights: • There is interest in variation in metabolic effects of chronic low-dose ionizing radiation • A random effect meta-analysis of effect sizes of radioactive contamination was performed • We found significant effects of radiation on oxidative damage and antioxidant response • We found significant heterogeneity among

Analysis of radiation damage in on-orbit solar array of Venus explorer Akatsuki

International Nuclear Information System (INIS)

Toyota, Hiroyuki; Shimada, Takanobu; Takahashi, You; Imamura, Takeshi; Hada, Yuko; Ishii, Takako T.; Isobe, Hiroaki; Asai, Ayumi; Shiota, Daikou

2013-01-01

This paper describes an analysis of radiation damage in solar array of Venus explorer Akatsuki observed on orbit. The output voltage of the solar array have shown sudden drops, which are most reasonably associated with radiation damage, three times since its launch. The analysis of these radiation damages is difficult, because no direct observation data of the spectra and the amount of the high-energy particles is available. We calculated the radiation damage using the relative damage coefficient (RDC) method assuming a typical spectral shape of protons. (author)

Carrier concentration effects on radiation damage in InP

International Nuclear Information System (INIS)

Yamaguchi, M.; Ando, K.; Uemura, C.

1984-01-01

Minority carrier diffusion length and carrier concentration studies have been made on room-temperature 1-MeV electron irradiated liquid-encapsulated Czochralski grown Zn-doped p-InP. The damage rate for the diffusion length and carrier removal rate due to irradiation have been found to strongly decrease with an increase in the carrier concentration in InP. These phenomena suggest that the induced defects interact with impurities in InP. A preliminary study on the annealing behavior has also been performed

Radiation Damage in the LHCb VELO

CERN Multimedia

Harrison, Jon

2011-01-01

The VErtex LOcator (VELO) is a silicon strip detector designed to reconstruct particle tracks and vertices produced by proton-proton interactions near to the LHCb interaction point. The excellent track resolution and decay vertex separation provided by the VELO are essential to all LHCb analyses. For the integrated luminosity delivered by the LHC up to the end of $2011$ the VELO is exposed to higher particle fluences than any other silicon detector of the four major LHC experiments. These proceedings present results from radiation damage studies carried out during the first two years of data taking at the LHC. Radiation damage has been observed in all of the $88$ VELO silicon strip sensors, with many sensors showing evidence of type-inversion in the highest fluence regions. Particular attention has been given to the two \

Activation and radiation damage in the environment of hadron accelerators

CERN Document Server

Kiselev, Daniela

2013-01-01

A component which suffers radiation damage usually also becomes radioactive, since the source of activation and radiation damage is the interaction of the material with particles from an accelerator or with reaction products. However, the underlying mechanisms of the two phenomena are different. These mechanisms are described here. Activation and radiation damage can have far-reaching consequences. Components such as targets, collimators, and beam dumps are the first candidates for failure as a result of radiation damage. This means that they have to be replaced or repaired. This takes time, during which personnel accumulate dose. If the dose to personnel at work would exceed permitted limits, remote handling becomes necessary. The remaining material has to be disposed of as radioactive waste, for which an elaborate procedure acceptable to the authorities is required. One of the requirements of the authorities is a complete nuclide inventory. The methods used for calculation of such inventories are presented,...

Principal and secondary luminescence lifetime components in annealed natural quartz

International Nuclear Information System (INIS)

Chithambo, M.L.; Ogundare, F.O.; Feathers, J.

2008-01-01

Time-resolved luminescence spectra from quartz can be separated into components with distinct principal and secondary lifetimes depending on certain combinations of annealing and measurement temperature. The influence of annealing on properties of the lifetimes related to irradiation dose and temperature of measurement has been investigated in sedimentary quartz annealed at various temperatures up to 900 deg. C. Time-resolved luminescence for use in the analysis was pulse stimulated from samples at 470 nm between 20 and 200 deg. C. Luminescence lifetimes decrease with measurement temperature due to increasing thermal effect on the associated luminescence with an activation energy of thermal quenching equal to 0.68±0.01eV for the secondary lifetime but only qualitatively so for the principal lifetime component. Concerning the influence of annealing temperature, luminescence lifetimes measured at 20 deg. C are constant at about 33μs for annealing temperatures up to 600 0 C but decrease to about 29μs when the annealing temperature is increased to 900 deg. C. In addition, it was found that lifetime components in samples annealed at 800 deg. C are independent of radiation dose in the range 85-1340 Gy investigated. The dependence of lifetimes on both the annealing temperature and magnitude of radiation dose is described as being due to the increasing importance of a particular recombination centre in the luminescence emission process as a result of dynamic hole transfer between non-radiative and radiative luminescence centres

Radiation-damage calculations with NJOY

International Nuclear Information System (INIS)

MacFarlane, R.E.; Muir, D.W.; Mann, F.W.

1983-01-01

Atomic displacement, gas production, transmutation, and nuclear heating can all be calculated with the NJOY nuclear data processing system using evaluated data in ENDF/B format. Using NJOY helps assure consistency between damage cross sections and those used for transport, and NJOY provides convenient interface formats for linking data to application codes. Unique features of the damage calculation include a simple momentum balance treatment for radiative capture and a new model for (n, particle) reactions based on statistical model calculations. Sample results for iron and nickel are given and compared with the results of other methods

The role of radiation damage analysis in the fusion program

International Nuclear Information System (INIS)

Doran, D.G.

1983-01-01

The objective of radiation damage analysis is the prediction of the performance of facility components exposed to a radiation environment. The US Magnetic Fusion Energy materials program includes an explicit damage analysis activity within the Damage Analysis and Fundamental Studies (DAFS) Program. Many of the papers in these Proceedings report work done directly or indirectly in support of the DAFS program. The emphasis of this program is on developing procedures, based on an understanding of damage mechanisms, for applying data obtained in diverse radiation environments to the prediction of component behavior in fusion devices. It is assumed that the Fusion Materials Irradiation Test Facility will be available in the late 1980s to test (and calibrate where necessary) correlation procedures to the high fluences expected in commercial reactors. (orig.)

Radiation damage in silicon. Defect analysis and detector properties

Energy Technology Data Exchange (ETDEWEB)

Hoenniger, F.

2008-01-15

Silicon microstrip and pixel detectors are vital sensor-components as particle tracking detectors for present as well as future high-energy physics (HEP) experiments. All experiments at the large Hadron Collider (LHC) are equipped with such detectors. Also for experiments after the upgrade of the LHC (the so-called Super-LHC), with its ten times higher luminosity, or the planned International Linear Collider (ILC) silicon tracking detectors are forseen. Close to the interaction region these detectors have to face harsh radiation fields with intensities above the presently tolerable level. defect engineering of the used material, e. g. oxygen enrichment of high resistivity float zone silicon and growing of thin low resistivityepitaxial layers on Czochralski silicon substrates has been established to improve the radiation hardness of silicon sensors. This thesis focuses mainly on the investigation of radiation induced defects and their differences observed in various kinds of epitaxial silicon material. Comparisons with other materials like float zone or Czochralski silicon are added. Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Current (TSC) measurements have been performed after {gamma}-, electron-, proton- and neutron-irradiation. The differenced in the formation of vacancy and interstitial related defects as well as so-called clustered regions were investigated for various types of irradiation. In addition to the well known defects VO{sub i}, C{sub i}O{sub i}, C{sub i}C{sub s}, VP or V{sub 2} several other defect complexes have been found and investigated. Also the material dependence of the defect introduction rates and the defect annealing behavior has been studied by isothermal and isochronal annealing experiments. Especially the IO{sub 2} defect which is an indicator for the oxygen-dimer content of the material has been investigated in detail. On the basis of radiation induced defects like the bistable donor (BD) defect and a deep

Radiation damage in silicon. Defect analysis and detector properties

International Nuclear Information System (INIS)

Hoenniger, F.

2008-01-01

Silicon microstrip and pixel detectors are vital sensor-components as particle tracking detectors for present as well as future high-energy physics (HEP) experiments. All experiments at the large Hadron Collider (LHC) are equipped with such detectors. Also for experiments after the upgrade of the LHC (the so-called Super-LHC), with its ten times higher luminosity, or the planned International Linear Collider (ILC) silicon tracking detectors are forseen. Close to the interaction region these detectors have to face harsh radiation fields with intensities above the presently tolerable level. defect engineering of the used material, e. g. oxygen enrichment of high resistivity float zone silicon and growing of thin low resistivityepitaxial layers on Czochralski silicon substrates has been established to improve the radiation hardness of silicon sensors. This thesis focuses mainly on the investigation of radiation induced defects and their differences observed in various kinds of epitaxial silicon material. Comparisons with other materials like float zone or Czochralski silicon are added. Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Current (TSC) measurements have been performed after γ-, electron-, proton- and neutron-irradiation. The differenced in the formation of vacancy and interstitial related defects as well as so-called clustered regions were investigated for various types of irradiation. In addition to the well known defects VO i , C i O i , C i C s , VP or V 2 several other defect complexes have been found and investigated. Also the material dependence of the defect introduction rates and the defect annealing behavior has been studied by isothermal and isochronal annealing experiments. Especially the IO 2 defect which is an indicator for the oxygen-dimer content of the material has been investigated in detail. On the basis of radiation induced defects like the bistable donor (BD) defect and a deep acceptor, a model has been introduced to

Use of heavy ions to model radiation damage of metals

International Nuclear Information System (INIS)

Shirokov, S.V.; Vyshemirskij, M.P.

2011-01-01

The methods for modeling radiation damage of metals using heavy ions are reviewed and the results obtained are analyzed. It is shown that irradiation of metals with heavy ion can simulate neutron exposure with the equivalent dose with adequate accuracy and permits a detailed analysis of radiation damage of metals

Progress on clustered DNA damage in radiation research

International Nuclear Information System (INIS)

Yang Li'na; Zhang Hong; Di Cuixia; Zhang Qiuning; Wang Xiaohu

2012-01-01

Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in detail in this paper. (authors)

Compilation of radiation damage test data. Pt. 3

International Nuclear Information System (INIS)

Beynel, P.; Maier, P.; Schoenbacher, H.

1982-01-01

This handbook gives the results of radiation damage tests on various engineering materials and components intended for installation in radiation areas of the CERN high-energy particle accelerators. It complements two previous volumes covering organic cable-insulating materials and thermoplastic and thermosetting resins. The irradiation have been carried out at various radiation sources and the results of the different tests are reported, sometimes illustrated by tables and graphs to show the variation of the measured property with absorbed radiation dose. For each entry, an appreciation of the radiation resistance is given, based on measurement data, indicating the range of damage (moderate to severe) for doses from 10 to 10 8 Gy. Also included are tables, selected from published reports, of general relative radiation effects for several groups of materials, to which there are systematic cross-references in the alphabetical part. This third and last volume contains cross-references to all the materials presented up to now, so that it can be used as a guide to the three volumes. (orig.)

Infrared thermal annealing device

International Nuclear Information System (INIS)

Gladys, M.J.; Clarke, I.; O'Connor, D.J.

2003-01-01

A device for annealing samples within an ultrahigh vacuum (UHV) scanning tunneling microscopy system was designed, constructed, and tested. The device is based on illuminating the sample with infrared radiation from outside the UHV chamber with a tungsten projector bulb. The apparatus uses an elliptical mirror to focus the beam through a sapphire viewport for low absorption. Experiments were conducted on clean Pd(100) and annealing temperatures in excess of 1000 K were easily reached

The dependence of radiation damage analysis on neutron dosimetry

International Nuclear Information System (INIS)

Goland, A.N.; Parkin, D.M.

1977-01-01

The characteristics of defect production in neutron spectra can be determined by utilizing neutron cross section data (e.g. ENDF/B), detailed neutron spectral data and radiation damage models. The combination of neutron cross section and spectral data is a fundamental starting point in applying damage models. Calculations using these data and damage models show that there are significant differences in the way defects are produced in various neutron spectra. Nonelastic events dominate the recoil energy distribution in high-energy neutron sources such as those based upon fusion and deuteron-breakup reactions. Therefore, high-energy neutron cross sections must be measured or calculated to supplement existing data files. Radiation damage models can then be used to further characterize the diverse neutron spectra

Radiation-induced DNA damage as a function of DNA hydration

International Nuclear Information System (INIS)

Swarts, S.G.; Miao, L.; Wheeler, K.T.; Sevilla, M.D.; Becker, D.

1995-01-01

Radiation-induced DNA damage is produced from the sum of the radicals generated by the direct ionization of the DNA (direct effect) and by the reactions of the DNA with free radicals formed in the surrounding environment (indirect effect). The indirect effect has been believed to be the predominant contributor to radiation-induced intracellular DNA damage, mainly as the result of reactions of bulk water radicals (e.g., OH·) with DNA. However, recent evidence suggests that DNA damage, derived from the irradiation of water molecules that are tightly bound in the hydration layer, may occur as the result of the transfer of electron-loss centers (e.g. holes) and electrons from these water molecules to the DNA. Since this mechanism for damaging DNA more closely parallels that of the direct effect, the irradiation of these tightly bound water molecules may contribute to a quasi-direct effect. These water molecules comprise a large fraction of the water surrounding intracellular DNA and could account for a significant proportion of intracellular radiation-induced DNA damage. Consequently, the authors have attempted to characterize this quasi-direct effect to determine: (1) the extent of the DNA hydration layer that is involved with this effect, and (2) what influence this effect has on the types and quantities of radiation-induced DNA damage

Nuclear techniques of analysis in diamond synthesis and annealing

Energy Technology Data Exchange (ETDEWEB)

Jamieson, D. N.; Prawer, S.; Gonon, P.; Walker, R.; Dooley, S.; Bettiol, A.; Pearce, J. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1996-12-31

Nuclear techniques of analysis have played an important role in the study of synthetic and laser annealed diamond. These measurements have mainly used ion beam analysis with a focused MeV ion beam in a nuclear microprobe system. A variety of techniques have been employed. One of the most important is nuclear elastic scattering, sometimes called non-Rutherford scattering, which has been used to accurately characterise diamond films for thickness and composition. This is possible by the use of a database of measured scattering cross sections. Recently, this work has been extended and nuclear elastic scattering cross sections for both natural boron isotopes have been measured. For radiation damaged diamond, a focused laser annealing scheme has been developed which produces near complete regrowth of MeV phosphorus implanted diamonds. In the laser annealed regions, proton induced x-ray emission has been used to show that 50 % of the P atoms occupy lattice sites. This opens the way to produce n-type diamond for microelectronic device applications. All these analytical applications utilize a focused MeV microbeam which is ideally suited for diamond analysis. This presentation reviews these applications, as well as the technology of nuclear techniques of analysis for diamond with a focused beam. 9 refs., 6 figs.

Nuclear techniques of analysis in diamond synthesis and annealing

Energy Technology Data Exchange (ETDEWEB)

Jamieson, D N; Prawer, S; Gonon, P; Walker, R; Dooley, S; Bettiol, A; Pearce, J [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-12-31

Nuclear techniques of analysis have played an important role in the study of synthetic and laser annealed diamond. These measurements have mainly used ion beam analysis with a focused MeV ion beam in a nuclear microprobe system. A variety of techniques have been employed. One of the most important is nuclear elastic scattering, sometimes called non-Rutherford scattering, which has been used to accurately characterise diamond films for thickness and composition. This is possible by the use of a database of measured scattering cross sections. Recently, this work has been extended and nuclear elastic scattering cross sections for both natural boron isotopes have been measured. For radiation damaged diamond, a focused laser annealing scheme has been developed which produces near complete regrowth of MeV phosphorus implanted diamonds. In the laser annealed regions, proton induced x-ray emission has been used to show that 50 % of the P atoms occupy lattice sites. This opens the way to produce n-type diamond for microelectronic device applications. All these analytical applications utilize a focused MeV microbeam which is ideally suited for diamond analysis. This presentation reviews these applications, as well as the technology of nuclear techniques of analysis for diamond with a focused beam. 9 refs., 6 figs.

Nuclear techniques of analysis in diamond synthesis and annealing

International Nuclear Information System (INIS)

Jamieson, D. N.; Prawer, S.; Gonon, P.; Walker, R.; Dooley, S.; Bettiol, A.; Pearce, J.

1996-01-01

Nuclear techniques of analysis have played an important role in the study of synthetic and laser annealed diamond. These measurements have mainly used ion beam analysis with a focused MeV ion beam in a nuclear microprobe system. A variety of techniques have been employed. One of the most important is nuclear elastic scattering, sometimes called non-Rutherford scattering, which has been used to accurately characterise diamond films for thickness and composition. This is possible by the use of a database of measured scattering cross sections. Recently, this work has been extended and nuclear elastic scattering cross sections for both natural boron isotopes have been measured. For radiation damaged diamond, a focused laser annealing scheme has been developed which produces near complete regrowth of MeV phosphorus implanted diamonds. In the laser annealed regions, proton induced x-ray emission has been used to show that 50 % of the P atoms occupy lattice sites. This opens the way to produce n-type diamond for microelectronic device applications. All these analytical applications utilize a focused MeV microbeam which is ideally suited for diamond analysis. This presentation reviews these applications, as well as the technology of nuclear techniques of analysis for diamond with a focused beam. 9 refs., 6 figs

Extra lethal damage due to residual incompletely repaired sublethal damage in hyperfractionated and continuous radiation treatment

Energy Technology Data Exchange (ETDEWEB)

Chen, J.; van de Geijn, J.; Goffman, T. (ROB, DCT, NCI, NIH, Bethesda, Maryland 20892 (US))

1991-05-01

In the conventional linear--quadratic model of single-dose response, the {alpha} and {beta} terms reflect lethal damage created {ital during} the delivery of a dose, from two different presumed molecular processes, one linear with dose, the other quadratic. With the conventional one-fraction-per-day (or less) regimens, the sublethal damage (SLD), presumably repairing exponentially over time, is essentially completely fixed by the time of the next dose of radiation. If this assumption is true, the effects of subsequent fractions of radiation should be independent, that is, there should be little, if any, reversible damage left from previous fractions, at the time of the next dose. For multiple daily fractions, or for the limiting case, continuous radiation, this simplification may overlook damaged cells that have had insufficient time for repair. A generalized method is presented for accounting for extra lethal damage (ELD) arising from such residual SLD for hyperfractionation and continuous irradiation schemes. It may help to predict differences in toxicity and tumor control, if any, obtained with unconventional'' treatment regimens. A key element in the present model is the finite size and the dynamic character of the pool of sublethal damage. Besides creating the usual linear and quadratic components of lethal damage, each new fraction converts a certain fraction of the existing SLD into ELD, and creates some new SLD.

Extra lethal damage due to residual incompletely repaired sublethal damage in hyperfractionated and continuous radiation treatment

International Nuclear Information System (INIS)

Chen, J.; van de Geijn, J.; Goffman, T.

1991-01-01

In the conventional linear--quadratic model of single-dose response, the α and β terms reflect lethal damage created during the delivery of a dose, from two different presumed molecular processes, one linear with dose, the other quadratic. With the conventional one-fraction-per-day (or less) regimens, the sublethal damage (SLD), presumably repairing exponentially over time, is essentially completely fixed by the time of the next dose of radiation. If this assumption is true, the effects of subsequent fractions of radiation should be independent, that is, there should be little, if any, reversible damage left from previous fractions, at the time of the next dose. For multiple daily fractions, or for the limiting case, continuous radiation, this simplification may overlook damaged cells that have had insufficient time for repair. A generalized method is presented for accounting for extra lethal damage (ELD) arising from such residual SLD for hyperfractionation and continuous irradiation schemes. It may help to predict differences in toxicity and tumor control, if any, obtained with ''unconventional'' treatment regimens. A key element in the present model is the finite size and the dynamic character of the pool of sublethal damage. Besides creating the usual linear and quadratic components of lethal damage, each new fraction converts a certain fraction of the existing SLD into ELD, and creates some new SLD

Atomic structure of radiation damages in FCC-metals after neutron irradiation

International Nuclear Information System (INIS)

Popova, E.V.; Ivchenko, V.A.; Kozlov, A.V.

2005-01-01

Full text: Radiation clusters, formed at a neutron irradiation, are a product of evolution of cascade areas. The quantitative information about clusters can be used for verification of calculations of cascade damage ability, in particular, cascade efficiency. Data about concentration clusters and an average of the vacancies containing in them, allow to receive total of the vacancies reserved in them and to use them for comparison to results of calculations of cascade damage ability. A correctness of such comparison by that above, than below temperature of a neutron irradiation. The purpose of work was experimental studying radiation clusters formed in FCC-metals at a low temperature neutron irradiation methods of dilatometry, field ion (FIM) and transmission electronic microscopy (TEM). Radiation clusters were studied: in industrial austenite steel C0.05Crl6Nil5Mo2Mnl, irradiated in reactor Rw-2a at temperature 310 K up to fluence intermediate and fast neutrons (with E > 0,1 MeV) 6.7·l0 21 m -2 ; in a modelling material - Pt (cleanliness of 99.99 %) with the same - FCC-structure in an initial condition and after an irradiation in reactor RWW-2M at temperature 310 K up to fluence intermediate and fast neutrons (with E > 0.1 MeV) 3.5·10 22 m -2 . As a result of an irradiation of steel and pure Pt, in these materials by methods FIM and TEM many radiation clusters, the accelerated neutrons initiated by interaction with substance was revealed. It is established that these damage areas represent the depleted zones containing separate vacancies, and also small vacancy complexes, with the 'belt' interstitial atoms. The quantitative estimation of the sizes of such radiating defects is lead and their density in volume is experimentally established. So the neutron irradiation of steel at temperature 310 K up to fluence 6.7·10 21 m -2 causes formation radiation clusters which average diameter according to TEM makes 3 nanometers. Observable by methods FIM clusters have the

Characterization of matrix damage in ion-irradiated reactor vessel steel

International Nuclear Information System (INIS)

Fujii, Katsuhiko; Fukuya, Koji

2004-01-01

Exact nature of the matrix damage, that is one of radiation-induced nano-scale microstructural features causing radiation embrittlement of reactor vessel, in irradiated commercial steels has not been clarified yet by direct characterization using transmission electron microscopy (TEM). We designed a new preparation method of TEM observation samples and applied it to the direct TEM observation of the matrix damage in the commercial steel samples irradiated by ions. The simulation irradiation was carried out by 3 MeV Ni 2+ ion to a dose of 1 dpa at 290degC. Thin foil specimens for TEM observation were prepared using the modified focused ion beam method. A weak-beam TEM study was carried out for the observation of matrix damage in the samples. Results of this first detailed observation of the matrix damage in the irradiated commercial steel show that it is consisted of small dislocation loops. The observed and analyzed dislocation loops have Burgers vectors b = a , and a mean image size and the number density are 2.5 nm and about 1 x 10 22 m -3 , respectively. In this experiment, all of the observed dislocation loops were too small to determine the vacancy or interstitial nature of the dislocation loops directly. Although it is an indirect method, post-irradiation annealing was used to infer the loop nature. Most of dislocation loops were stable after the annealing at 400degC for 30 min. This result suggests that their nature is interstitial. (author)

High-temperature annealing of graphite: A molecular dynamics study

Science.gov (United States)

Petersen, Andrew; Gillette, Victor

2018-05-01

A modified AIREBO potential was developed to simulate the effects of thermal annealing on the structure and physical properties of damaged graphite. AIREBO parameter modifications were made to reproduce Density Functional Theory interstitial results. These changes to the potential resulted in high-temperature annealing of the model, as measured by stored-energy reduction. These results show some resemblance to experimental high-temperature annealing results, and show promise that annealing effects in graphite are accessible with molecular dynamics and reactive potentials.

Irradiation embrittlement and optimisation of annealing

International Nuclear Information System (INIS)

1993-01-01

This conference is composed of 30 papers grouped in 6 sessions related to the following themes: neutron irradiation effects in pressure vessel steels and weldments used in PWR, WWER and BWR nuclear plants; results from surveillance programmes (irradiation induced damage and annealing processes); studies on the influence of variations in irradiation conditions and mechanisms, and modelling; mitigation of irradiation effects, especially through thermal annealing; mechanical test procedures and specimen size effects

Irradiation embrittlement and optimisation of annealing

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

This conference is composed of 30 papers grouped in 6 sessions related to the following themes: neutron irradiation effects in pressure vessel steels and weldments used in PWR, WWER and BWR nuclear plants; results from surveillance programmes (irradiation induced damage and annealing processes); studies on the influence of variations in irradiation conditions and mechanisms, and modelling; mitigation of irradiation effects, especially through thermal annealing; mechanical test procedures and specimen size effects.

Radiation induced DNA damage and repair in mutagenesis

International Nuclear Information System (INIS)

Strniste, G.F.; Chen, D.J.; Okinaka, R.T.

1987-01-01

The central theme in cellular radiobiological research has been the mechanisms of radiation action and the physiological response of cells to this action. Considerable effort has been directed toward the characterization of radiation-induced DNA damage and the correlation of this damage to cellular genetic change that is expressed as mutation or initiating events leading to cellular transformation and ultimately carcinogenesis. In addition, there has been a significant advancement in their understanding of the role of DNA repair in the process of mutation leading to genetic change in cells. There is extensive literature concerning studies that address radiation action in both procaryotic and eucaryotic systems. This brief report will make no attempt to summarize this voluminous data but will focus on recent results from their laboratory of experiments in which they have examined, at both the cellular and molecular levels, the process of ionizing radiation-induced mutagenesis in cultured human cells

Automated analysis of damages for radiation in plastics surfaces

International Nuclear Information System (INIS)

Andrade, C.; Camacho M, E.; Tavera, L.; Balcazar, M.

1990-02-01

Analysis of damages done by the radiation in a polymer characterized by optic properties of polished surfaces, of uniformity and chemical resistance that the acrylic; resistant until the 150 centigrade grades of temperature, and with an approximate weight of half of the glass. An objective of this work is the development of a method that analyze in automated form the superficial damages induced by radiation in plastic materials means an images analyst. (Author)

Radiation damage in the alkali halide crystals

International Nuclear Information System (INIS)

Diller, K.M.

1975-10-01

A general review is given of the experimental data on radiation damage in the alkali halide crystals. A report is presented of an experimental investigation of irradiation produced interstitial dislocation loops in NaCl. These loops are found to exhibit the usual growth and coarsening behaviour during thermal annealing which operates by a glide and self-climb mechanism. It is shown that the recombination of defects in these crystals is a two stage process, and that the loss of interstitials stabilized at the loops is caused by extrinsic vacancies. The theoretical techniques used in simulating point defects in ionic crystals are described. Shell model potentials are derived for all the alkali halide crystals by fitting to bulk crystal data. The fitting is supplemented by calculations of the repulsive second neighbour interactions using methods based on the simple electron gas model. The properties of intrinsic and substitutional impurity defects are calculated. The HADES computer program is used in all the defect calculations. Finally the report returns to the problems of irradiation produced interstitial defects. The properties of H centres are discussed; their structure, formation energies, trapping at impurities and dimerization. The structure, formation energies and mobility of the intermediate and final molecular defects are then discussed. The thermodynamics of interstitial loop formation is considered for all the alklai halide crystals. The nucleation of interstitial loops in NaCl and NaBr is discussed, and the recombination of interstitial and vacancy defects. The models are found to account for all the main features of the experimental data. (author)

Silicon P.I.N. Junctions used for studies of radiation damage; Etude de l'irradiation aux neutrons rapides du silicium au moyen de jonctions P.I.N

Energy Technology Data Exchange (ETDEWEB)

Lanore, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-06-01

Irradiation of silicon P.I.N. junction has been studied primarily for the purpose of developing a radiation damage dosimeter, but also for the purpose of investigating silicon itself. It is known that the rate of recombination of electrons and holes is a linear function of defects introduced by neutron irradiation. Two methods have been used to measure that rate of recombination: forward characteristic measurements, recovery time measurements. In order to explain how these two parameters depend on recombination rate we have given a theory of the P.I.N. junction. We have also given an idea of the carrier lifetime dependence versus temperature. Annealing effects in the range of 70 to 700 K have also been studied, we found five annealing stages with corresponding activation energies. As an application for these studies, we developed a radiation damage dosimeter with which we made several experiments in facilities such as Naiade or Marias. (author) [French] L'irradiation de structures P.I.N. etait faite dans le but d'etudier principalement la mise au point d'un dosimetre a ''radiation damage'' et aussi pour etudier plus profondement le silicium lui-meme. On sait que le taux de recombinaison electrons-trous est une fonction lineaire du taux de defauts introduits par irradiation aux neutrons. Deux methodes ont ete utilisees pour atteindre ce taux de recombinaison: mesures de la caracteristique directe, mesures du temps de retournement. Pour expliquer de quelle facon ces parametres dependent du taux de recombinaison. Nous avons donne une theorie de la jonction P.I.N. Nous avons aussi donne l'allure des variations du temps de vie des porteurs en fonction de la temperature. Nous avons d'autre part effectue des recuits entre 70 et 700 K, domaine dans lequel nous avons trouve cinq etapes de ''guerison'' avec les energies d'activation correspondantes. En application de ces etudes nous avons mis ou point un

Computer simulation of radiation damage in NaCl using a kinetic rate reaction model

International Nuclear Information System (INIS)

Soppe, W.J.

1993-01-01

Sodium chloride and other alkali halides are known to be very susceptible to radiation damage in the halogen sublattice when exposed to ionizing radiation. The formation of radiation damage in NaCl has generated interest because of the relevance of this damage to the disposal of radioactive waste in rock salt formations. In order to estimate the long-term behaviour of a rock salt repository, an accurate theory describing the major processes of radiation damage in NaCl is required. The model presented in this paper is an extended version of the Jain-Lidiard model; its extensions comprise the effect of impurities and the colloid nucleation stage on the formation of radiation damage. The new model has been tested against various experimental data obtained from the literature and accounts for several well known aspects of radiation damage in alkali halides which were not covered by the original Jain-Lidiard model. The new model thus may be expected to provide more reliable predictions for the build-up of radiation damage in a rock salt nuclear waste repository. (Author)

Pulsed Q-switched ruby laser annealing of Bi implanted Si crystals investigated by channeling

International Nuclear Information System (INIS)

Deutch, B.I.; Shih-Chang, T.; Shang-Hwai, L.; Zu-Yao, Z.; Jia-Zeng, H.; Ren-Zhi, D.; Te-Chang, C.; De-Xin, C.

1979-01-01

Channeling was used to investigate pulsed, Q switched ruby-laser annealed and thermally annealed Si single crystals implanted with 40-keV Bi ions to a dose of 10 15 atoms/cm 2 . After thermal annealing, residual damage decreased with increasing annealing temperature to a minimum value of 30% at 900 0 C. The Bi atoms in substitutional sites reached a maximum value (50%) after annealing at 750 0 C but decreased with increasing annealing temperature. Out diffusion of Bi atoms occurred at temperatures higher than 625 0 C. For comparison, the residual damage disappeared almost completely after pulsed-laser annealing (30 ns pulse width, Energy, E = 3J/cm 2 ). The concentration of Bi in Si exceeded its solid solubility by an order of magnitude; 95% of Bi atoms were annealed to substitutional sites. Laser pulses of different energies were used to investigate the efficiency of annealing. (author)

Radiation damage of uranium

International Nuclear Information System (INIS)

Lazarevic, Dj.

1966-11-01

Study of radiation damage covered the following: Kinetics of electric resistance of uranium and uranium alloy with 1% of molybdenum dependent on the second phase and burnup rate; Study of gas precipitation and diffusion of bubbles by transmission electron microscopy; Numerical analysis of the influence of defects distribution and concentration on the rare gas precipitation in uranium; study of thermal sedimentation of uranium alloy with molybdenum; diffusion of rare gas in metal by gas chromatography method

A review on radiation damage of erythrocyte membranes

International Nuclear Information System (INIS)

Wang Junling; Wang Weidong; Qin Guangyong

2007-01-01

Biomembrane has very important biological function. Its damage will seriously disturb the directivity, the orderly nature and coordination of cell metabolism, and finally causes the cell death. This paper reviewed the effects of radiation damage on erythrocyte membrane in membrane composition, membrane function and oxidation resistance system. (authors)

DNA Damage by Ionizing Radiation: Tandem Double Lesions by Charged Particles

Science.gov (United States)

Huo, Winifred M.; Chaban, Galina M.; Wang, Dunyou; Dateo, Christopher E.

2005-01-01

Oxidative damages by ionizing radiation are the source of radiation-induced carcinogenesis, damage to the central nervous system, lowering of the immune response, as well as other radiation-induced damages to human health. Monte Carlo track simulations and kinetic modeling of radiation damages to the DNA employ available molecular and cellular data to simulate the biological effect of high and low LET radiation io the DNA. While the simulations predict single and double strand breaks and base damages, so far all complex lesions are the result of stochastic coincidence from independent processes. Tandem double lesions have not yet been taken into account. Unlike the standard double lesions that are produced by two separate attacks by charged particles or radicals, tandem double lesions are produced by one single attack. The standard double lesions dominate at the high dosage regime. On the other hand, tandem double lesions do not depend on stochastic coincidences and become important at the low dosage regime of particular interest to NASA. Tandem double lesions by hydroxyl radical attack of guanine in isolated DNA have been reported at a dosage of radiation as low as 10 Gy. The formation of two tandem base lesions was found to be linear with the applied doses, a characteristic of tandem lesions. However, tandem double lesions from attack by a charged particle have not been reported.

Primary radiation damage and disturbance in cell divisions

International Nuclear Information System (INIS)

Kim, Jin Kyu; Lee, Yun-Jong; Kim, Jae-Hun; Petin, Vladislav G.; Nili, Mohammad

2008-01-01

Survived cells from a homogeneous population exposed to ionizing radiation form various colonies of different sizes and morphology on a solid nutrient medium, which appear at different time intervals after irradiation. Such a phenomenon agrees well with the modern theory of microdosimetry and classical hit-and-target models of radiobiology. According to the hit-principle, individual cells exposed to the same dose of radiation are damaged in different manners. It means that the survived cells can differ in the content of sublethal damage (hits) produced by the energy absorbed into the cell and which is not enough to give rise to effective radiation damage which is responsible for cell killing or inactivation. In diploid yeast cells, the growth rate of cells from 250 colonies of various sizes appeared at different time intervals after irradiation with 600 Gy of gamma radiation from a 60 Co isotopic source was analyzed. The survival rate after irradiation was 20%. Based on the analyses results, it was possible to categorize the clones grown from irradiated cells according to the number of sub-lesions from 1 to 4. The clones with various numbers of sub-lesions were shown to be different in their viability, radiosensitivity, sensitivity to environmental conditions, and the frequency of recombination and respiratory deficient mutations. Cells from unstable clones exhibited an enhanced radiosensitivity, and an increased portion of morphologically changed cells, nonviable cells and respiration mutants, as well. The degree of expression of the foregoing effects was higher if the number of primary sublethal lesions was greater in the originally irradiated cell. Disturbance in cell division can be characterized by cell inactivation or incorrect distribution of mitochondria between daughter cells. Thus, the suggested methodology of identification of cells with a definite number of primary sublethal lesions will promote further elucidation of the nature of primary radiation

Radiation damage in CTR magnet components

International Nuclear Information System (INIS)

Ullmaier, H.

1976-01-01

Data are reviewed (already existing or to be acquired) which should allow prediction of the behavior of large superconducting coils in the radiation field of a future fusion reactor. The electrical and mechanical stability of such magnets is determined by the irradiation induced deterioration of the magnet components, i.e., (a) changes in critical current, field and temperature of the superconductor (NbTi, A-15 phases), (b) resistivity increase in the stabilizer (Cu, Al), and (c) changes in mechanical and dielectric properties of insulators and spacers. Recent low temperature simulation experiments (with fission neutrons and heavy ions) show that the superconductor will not be the critical component of a fusion magnet--at least as far as radiation damage is concerned. Much more severe is the loss of stability due to the resistivity increase of the stabilizing material. It seems, however, that the magnitude of this effect can be predicted rather reliably and therefore taken into account in the coil design. Almost no data exist about the low temperature behavior of insulator and spacer materials in a radiation field. Furthermore, very little is known about the nature of the radiation damage in non-metals, which makes extrapolations of the few existing data to other materials or to other doses highly speculative. Only future experiments can decide if the insulators will be the limiting component of a CTR magnet or not

The Status of Radiation Damage Experiments

International Nuclear Information System (INIS)

Strachan, Denis M.; Scheele, Randall D.; Icenhower, Jonathan P.; Kozelisky, Anne E.; Sell, Richard L.; Legore, Virginia L.; Schaef, Herbert T.; O'Hara, Matthew J.; Brown, Christopher F.; Buchmiller, William C.

2001-01-01

Experiments have been on-going for about two years to determine the effects that radiation damage have on the physical and chemical properties of candidate titanate ceramics for the immobilization of plutonium. We summarize the results of these experiments in this document

Influence of oxygen on the annealing of radioactive defects in germanium

International Nuclear Information System (INIS)

Gasimov, G.M.; Mustafayev, Yn.M.; Gasimova, V.G.

2002-01-01

The isochronal annealing were carried out in the wide temperature range, for the establishment of oxygen influence on the annealing of radioactive defects (Rd) in any radiated germanium samples, concentrated with oxygen up to concentration of 9.7·10 16 cm -3 . It is shown that the curves of isochronal annealing of one of the such samples 1, with primary current charge concentration of 9.0·10 cm 14 , radiated by integral electron flow of φ= 8.0·10 16 cm -3 , at 293 K and also the non-oxygen samples 2, with primary concentration of 1.7·10 cm -3 , radiated at above mentioned conditions. The sample 1 is converted by radiation to p-type, but the conversion not occur in samples 2. It is illustrated, that that there is two annealing stage at 340-430 K, for the samples 2, which in results takes place the complete annealing of the RD. At 300 K the annealing takes place in samples of 1, but at 340 K - the reverse annealing of RD. The sample was at compensated state in the temperature range of 360-400 K. An annealing of RD takes place again at 440 K and the sample re-converted its conductivity type. The reverse annealing at 480 K, and at about 510 K, the substantial annealing of the defects has been observed, which in results a sample restores it's primary parameters. The carried out experiments show that as in converted, and also in n-type be samples, Is observed the reverse annealing of RD, but the reverse annealing of current charge carriers in n-type samples is observed only at such conditions, of the integral flow of accelerated elections exceeds the primary concentration of current charge carriers about 4 time of magnitude (φ≥4n 0 ). Besides, the complete annealing of RD in germanium samples concentrated with oxygen, takes place at more high temperatures in comparison with the non-oxygen samples

Laser annealing of ion implanted silicon

International Nuclear Information System (INIS)

White, C.W.; Narayan, J.; Young, R.T.

1978-11-01

The physical and electrical properties of ion implanted silicon annealed with high powered ruby laser radiation are summarized. Results show that pulsed laser annealing can lead to a complete removal of extended defects in the implanted region accompanied by incorporation of dopants into lattice sites even when their concentration far exceeds the solid solubility limit

Radiation damage effect on avalanche photodiodes

CERN Document Server

Baccaro, S; Cavallari, F; Da Ponte, V; Deiters, K; Denes, P; Diemoz, M; Kirn, Th; Lintern, A L; Longo, E; Montecchi, M; Musienko, Y; Pansart, J P; Renker, D; Reucroft, S; Rosi, G; Rusack, R; Ruuska, D; Stephenson, R; Torbet, M J

1999-01-01

Avalanche Photodiodes have been chosen as photon sensors for the electromagnetic calorimeter of the CMS experiment at the LHC. These sensors should operate in the 4T magnetic field of the experiment. Because of the high neutron radiation in the detector extensive studies have been done by the CMS collaboration on the APD neutron radiation damage. The characteristics of these devices after irradiation have been analized, with particular attention to the quantum efficiency and the dark current. The recovery of the radiation induced dark current has been studied carefully at room temperature and at slightly lower and higher temperatures. The temperature dependence of the defects decay-time has been evaluated.

Radiation damage in lithium orthosilicate

Energy Technology Data Exchange (ETDEWEB)

Noda, K.; Nakazawa, T.; Ishii, Y.; Fukai, K.; Watanabe, H. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment); Matsui, H.; Vollath, D.

1993-11-01

Radiation damage in lithium orthosilicate (Li[sub 4]SiO[sub 4]) and Al-doped Li[sub 4]SiO[sub 4] (Li[sub 3.7]Al[sub 0.1]SiO[sub 4]) irradiated with oxygen ions was studied with ionic conductivity measurements, Raman spectroscopy, Fourier transform infrared photo-acoustic spectroscopy (FT-IR PAS) and transmission electron microscopy. It was seen from the ionic conductivity measurements that lithium-ion vacancies were introduced as irradiation defects for Li-ions sites in both materials due to the irradiation. By the Raman spectroscopy, oxygen atoms in SiO[sub 4] tetrahedra were considered to be preferentially displaced due to the irradiation for Li[sub 4]SiO[sub 4], although only a decrease of the number of SiO[sub 4] tetrahedra occurred for Li[sub 3.7]Al[sub 0.1]SiO[sub 4] by displacement of both silicon and oxygen atoms. Decomposition of SiO[sub 4] tetrahedra and formation of some new phases having Si-O-Si and Si-O bonds were found to take place for both Li[sub 4]SiO[sub 4] and Li[sub 3.7]Al[sub 0.1]SiO[sub 4] by FT-IR PAS. In the electron microscopy, damage microstructure consisting of many voids or cavities and amorphization were observed for Li[sub 4]SiO[sub 4] irradiated with oxygen ions. The recovery behavior of radiation damage mentioned above was also investigated. (author).

Radiation damage in natural and synthetic halite. Progress report January 1992 - February 1993

International Nuclear Information System (INIS)

Garcia Celma, A.

1993-12-01

This report complements the information presented in the report of December 1992 regarding the research performed at the ECN on radiation damage in salt. It consists of two parts. The first part regards the amount of stored energy which can be developed by gamma-irradiation on different types of halite and considers both the effect of low dose rates in developing radiation damage, and the possible saturation level of radiation damage in natural halite. The second part presents a model to simulate radiation damage development which incorporates some extensions in the Jain-Lidiard model. Due to malfunction of the Small Angle Neutron Scattering installation, neither the previously reported results nor the newly obtained can be trusted and therefore are not reported here. These results regard the shape, size and size distribution of radiation damage defects. (orig.)

Contribution of endogenous and exogenous damage to the total radiation-induced damage in the bacterial spore

International Nuclear Information System (INIS)

Jacobs, G.P.; Samuni, A.; Czapski, G.

1980-01-01

Radical scavengers such as polyethylene glycol 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous damage to the total radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous

Radiation damage in silicon detectors

CERN Document Server

Lindström, G

2003-01-01

Radiation damage effects in silicon detectors under severe hadron and gamma-irradiation are surveyed, focusing on bulk effects. Both macroscopic detector properties (reverse current, depletion voltage and charge collection) as also the underlying microscopic defect generation are covered. Basic results are taken from the work done in the CERN-RD48 (ROSE) collaboration updated by results of recent work. Preliminary studies on the use of dimerized float zone and Czochralski silicon as detector material show possible benefits. An essential progress in the understanding of the radiation-induced detector deterioration had recently been achieved in gamma irradiation, directly correlating defect analysis data with the macroscopic detector performance.

Radiation damage effects in solids special topic volume with invited peer reviewed papers only

CERN Document Server

Virk, Hardev Singh

2013-01-01

Public interest and concern about radiation damage effects has increased during recent times. Nuclear radiation proved to be a precursor for the study of radiation damage effects in solids. In general, all types of radiation, e.g. X-ray, gamma ray, heavy ions, fission fragments and neutrons produce damage effects in materials. Radiation damage latent tracks in solids find applications in nuclear and elementary particle physics, chemistry, radiobiology, earth sciences, nuclear engineering, and a host of other areas such as nuclear safeguards, virus counting, ion track filters, uranium exploration and archaeology. Radiation dosimetry and reactor shielding also involve concepts based on radiation damage in solids. This special volume consists of ten Chapters, including Review and Research Papers on various topics in this field.Physical scientists known to be investigating the effects of radiation on material were invited to contribute research and review papers on the areas of their specialty. The topics include...

Radiation damage in flash memory cells

International Nuclear Information System (INIS)

Claeys, C.; Ohyama, H.; Simoen, E.; Nakabayashi, M.; Kobayashi, K.

2002-01-01

Results are presented of a study on the effects of total ionization dose and displacement damage, induced by high-energy electrons, protons and alphas, on the performance degradation of flash memory cells integrated in a microcomputer. A conventional stacked-gate n-channel flash memory cell using a 0.8 μm n-polysilicon gate technology is employed. Irradiations by 1-MeV electrons and 20-MeV protons and alpha particles were done at room temperature. The impact of the fluence on the input characteristics, threshold voltage shift and drain and gate leakage was investigated. The threshold voltage change for proton and alpha irradiations is about three orders of magnitude larger than that for electrons. The performance degradation is mainly caused by the total ionization dose (TID) damage in the tunnel oxide and in the interpoly dielectric layer and by the creation of interface traps at the Si-SiO 2 interface. The impact of the irradiation temperature on the device degradation was studied for electrons and gammas, pointing out that irradiation at room temperature is mostly the worst case. Finally, attention is given to the impact of isochronal and isothermal annealing on the recovery of the degradation introduced after room temperature proton and electron irradiation

Alleviation of acute radiation damages by post-irradiation treatments

International Nuclear Information System (INIS)

Kurishita, A.; Ono, T.

1992-01-01

Radiation induced hematopoietic and gastro-intestinal damages in mice were tried to alleviate experimentally by post-treatment. Combined treatment of OK-432 and aztreonam clearly prevented the radiation induced sepsis and elevated the survival rate in mice; the survival was 80% in the OK-432 plus aztreonam group while it was 55% in the group treated with OK-432 alone and 0% with saline. Irsogladine maleate, an anti-ulcer drug, increased the survival rate of jejunal crypt stem cells with a clear dose-related trend. The D 0 for irsogladine maleate was 2.8 Gy although it was 2.3 Gy for saline, These findings suggest that some conventional drugs are effective for radiation induced hematopoietic and gastro-intestinal damages and the possibility that they can be applied for people exposed to radiation accidentally. (author)

Damage pattern as a function of radiation quality and other factors.

Science.gov (United States)

Burkart, W; Jung, T; Frasch, G

1999-01-01

An understanding of damage pattern in critical cellular structures such as DNA is an important prerequisite for a mechanistic assessment of primary radiation damage, its possible repair, and the propagation of residual changes in somatic and germ cells as potential contributors to disease or ageing. Important quantitative insights have been made recently on the distribution in time and space of critical lesions from direct and indirect action of ionizing radiation on mammalian cells. When compared to damage from chemicals or from spontaneous degradation, e.g. depurination or base deamination in DNA, the potential of even low-LET radiation to create local hot spots of damage from single particle tracks is of utmost importance. This has important repercussions on inferences from critical biological effects at high dose and dose rate exposure situations to health risks at chronic, low-level exposures as experienced in environmental and controlled occupational settings. About 10,000 DNA lesions per human cell nucleus and day from spontaneous degradation and chemical attack cause no apparent effect, but a dose of 4 Gy translating into a similar number of direct and indirect DNA breaks induces acute lethality. Therefore, single lesions cannot explain the high efficiency of ionizing radiation in the induction of mutation, transformation and loss of proliferative capacity. Clustered damage leading to poorly repairable double-strand breaks or even more complex local DNA degradation, correlates better with fixed damage and critical biological endpoints. A comparison with other physical, chemical and biological agents indicates that ionizing radiation is indeed set apart from these by its unique micro- and nano-dosimetric traits. Only a few other agents such as bleomycin have a similar potential to cause complex damage from single events. However, in view of the multi-stage mechanism of carcinogenesis, it is still an open question whether dose-effect linearity for complex

Implantation activation annealing of Si-implanted gallium nitride at temperatures > 1,100 C

International Nuclear Information System (INIS)

Zolper, J.C.; Han, J.; Biefeld, R.M.

1997-01-01

The activation annealing of Si-implanted GaN is reported for temperatures from 1,100 to 1,400 C. Although previous work has shown that Si-implanted GaN can be activated by a rapid thermal annealing at ∼1,100 C, it was also shown that significant damage remained in the crystal. Therefore, both AlN-encapsulated and uncapped Si-implanted GaN samples were annealed in a metal organic chemical vapor deposition system in a N 2 /NH 3 ambient to further assess the annealing process. Electrical Hall characterization shows increases in carrier density and mobility for annealing up to 1,300 C before degrading at 1,400 C due to decomposition of the GaN epilayer. Rutherford backscattering spectra show that the high annealing temperatures reduce the implantation induced damage profile but do not completely restore the as-grown crystallinity

Effects of primary recoil (PKA) energy spectrum on radiation damage in fcc metals

International Nuclear Information System (INIS)

Iwata, Tadao; Iwase, Akihiro

1997-10-01

Irradiation effects by different energetic particles such as electrons, various ions and neutrons are compared in fcc metals, particularly in Cu and Ni. It is discussed on the statistical consideration that the logarithm of the so-called PKA median energy, log T 1/2 , is a good representative to characterize the primary recoil (i.e. PKA) energy spectrum with the resultant defect production. For the irradiations of electrons, various ions and neutrons to Cu and Ni, fundamental physical quantities such as the fraction of stage I recovery, the defect production cross sections and the radiation annealing cross sections can be well scaled as a function of log T 1/2 , if the effects of the electron excitation caused by irradiating ions are excluded. Namely, all data of the respective physical quantity lie on a single continuous curve as a function of log T 1/2 . This characteristic curve is utilized to predict the damage accumulation (i.e. defect concentration) as a function of dpa in Cu and Ni with the PKA median energy as a parameter. (author)

Effects of primary recoil (PKA) energy spectrum on radiation damage in fcc metals

Energy Technology Data Exchange (ETDEWEB)

Iwata, Tadao; Iwase, Akihiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-10-01

Irradiation effects by different energetic particles such as electrons, various ions and neutrons are compared in fcc metals, particularly in Cu and Ni. It is discussed on the statistical consideration that the logarithm of the so-called PKA median energy, log T{sub 1/2}, is a good representative to characterize the primary recoil (i.e. PKA) energy spectrum with the resultant defect production. For the irradiations of electrons, various ions and neutrons to Cu and Ni, fundamental physical quantities such as the fraction of stage I recovery, the defect production cross sections and the radiation annealing cross sections can be well scaled as a function of log T{sub 1/2}, if the effects of the electron excitation caused by irradiating ions are excluded. Namely, all data of the respective physical quantity lie on a single continuous curve as a function of log T{sub 1/2}. This characteristic curve is utilized to predict the damage accumulation (i.e. defect concentration) as a function of dpa in Cu and Ni with the PKA median energy as a parameter. (author)

Potential radiation damage: Storage tanks for liquid radioactive waste

International Nuclear Information System (INIS)

Caskey, G.R. Jr.

1992-01-01

High level waste at SRS is stored in carbon steel tanks constructed during the period 1951 to 1981. This waste contains radionuclides that decay by alpha, beta, or gamma emission or are spontaneous neutronsources. Thus, a low intensity radiation field is generated that is capable of causing displacement damage to the carbon steel. The potential for degradation of mechanical properties was evaluated by comparing the estimated displacement damage with published data relating changes in Charpy V-notch (CVN) impact energy to neutron exposure. Experimental radiation data was available for three of the four grades of carbonsteel from which the tanks were constructed and is applicable to all four steels. Estimates of displacement damage arising from gamma and neutron radiation have been made based on the radionuclide contents for high level waste that are cited in the Safety Analysis Report (SAR) for the Liquid Waste Handling Facilities in the 200-Area. Alpha and beta emissions do not penetrate carbon steel to a sufficient depth to affect the bulk properties of the tank walls but may aggravate corrosion processes. The damage estimates take into account the source of the waste (F- or H-Area), the several types of tank service, and assume wateras an attenuating medium. Estimates of displacement damage are conservative because they are based on the highest levels of radionuclide contents reported in the SAR and continuous replenishment of the radionuclides

Temperature effects on radiation damage in plastic detectors

International Nuclear Information System (INIS)

Mendoza A, D.

1996-01-01

The objective of present work was to study the temperature effect on radiation damage registration in the structure of a Solid State Nuclear Track Detector of the type CR-39. In order to study the radiation damage as a function of irradiation temperature, sheets of CR-39 detectors were irradiated with electron beams, simulating the interaction of positive ions. CR-39 detectors were maintained at a constant temperature from room temperature up to 373 K during irradiation. Two techniques were used from analyzing changes in the detector structure: Electronic Paramagnetic Resonance (EPR) and Infrared Spectroscopy (IR). It was found by EPR analysis that the amount of free radicals decrease as irradiation temperature increases. The IR spectrums show yield of new functional group identified as an hydroxyl group (OH). A proposed model of interaction of radiation with CR-39 detectors is discussed. (Author)

Radiation damage studies for the DOe silicon detector

International Nuclear Information System (INIS)

Lehner, Frank

2004-01-01

We report on irradiation studies performed on spare production silicon detector modules for the current DOe silicon detector. The lifetime expectations due to radiation damage effects of the existing silicon detector are reviewed. A new upgrade project was started with the goal of a complete replacement of the existing silicon detector. In that context, several investigations on the radiation hardness of new prototype silicon microstrip detectors were carried out. The irradiation on different detector types was performed with 10 MeV protons up to fluences of 10 14 p/cm 2 at the J.R. Mcdonald Laboratory at Kansas State University. The flux calibration was carefully checked using different normalisation techniques. As a result, we observe roughly 40-50% less radiation damage in silicon for 10 MeV p exposure than it is expected by the predicted NIEL scaling

PUMN: part I of the WINERY radiation damage computer simulation system

International Nuclear Information System (INIS)

Kuspa, J.P.; Edwards, D.R.; Tsoulfanidis, N.

1976-01-01

Results of computer work to simulate the response of crystalline materials to radiation are presented. To organize this and future work into a long range program of investigation, the WINERY Radiation Damage Computer Simulation System is proposed. The WINERY system is designed to solve the entire radiation damage problem from the incident radiation to the property changes which occur in the material, using a set of interrelated computer programs. One portion of the system, the PUMN program, has been used to obtain important radiation damage results with Fe 3 Al crystal. PUMN simulates the response of the atoms in a crystal to a knock-on atom. It yields the damage configuration of the crystal by considering the dynamic interaction of all the atoms of the computational cell, up to 1000 atoms. The PUMN program provides the WINERY system with results for the number of displacements, N/sub d/, due to knock-on atoms with various energies. The values of N/sub d/ for Fe 3 Al were obtained at two different energies, 100 and 500 eV, for a variety of initial directions. These values are to be used to form a table of results for use in WINERY

Health effects of radiation damage

International Nuclear Information System (INIS)

Gasimova, K; Azizova, F; Mehdieva, K.

2012-01-01

Full text : A summary of the nature of radiactive contamination would be incomplete without some mention of the human health effects relatied to radioactivity and radioactive materials. Several excellent reviews at the variety of levels of detail have been written and should be consulted by the reader. Internal exposures of alpha and beta particles are important for ingested and inhaled radionuclides. Dosimetry models are used to estimate the dose from internally deposited radioactive particles. As mentioned above weighting parameters that take into account the radiation type, the biological half-life and the tissue or organ at risk are used to convert the physically absorbed dose in units of gray (or red) to the biologically significant committed equivalent dose and effective dose, measured in units of Sv (or rem). There is considerable controversy over the shape of the dose-response curve at the chronic low dose levels important for enviromental contamination. Proposed models include linear models, non-linear models and threshold models. Because risks at low dose must be extrapolated from available date at high doses, the shape of the dose-response curve has important implications for the environmental regulations used to protect the general public. The health effect of radiation damage depends on a combination of events of on the cellular, tissue and systemic levels. These lead to mutations and cellular of the irradiated parent cell. The dose level at which significant damage occurs depends on the cell type. Cells that reproduce rapidily, such as those found in bone marrow or the gastrointestinal tract, will be more sensitive to radiation than those that are longer lived, such as striated muscle or nerve cells. The effects of high radiation doses on an organ depends on the various cell types it contains

Application of annealing for extension of WWER vessel lives

International Nuclear Information System (INIS)

Badanin, V.; Dragunow, Yu.G.; Fedorov, V.; Gorynin, I.; Nickolaev, V.

1992-01-01

The safe operation of nuclear power plants (NPP) is dependent upon the assurance that the reactor pressure vessel will not fail in a brittle manner when the effects of radiation embrittlement are taken into account. The recovery of the properties of the irradiated materials is an important way of extending the operating life of a reactor vessel. The intent of this paper is to demonstrate the efficiency of thermal annealing for the recovery of reactor vessel material properties and to present the implications for extended service life. In order to substantiate the application of annealing to the extensior of the service life of vessels, detailed investigations were conducted which involved thermal annealing temperature and time, fast neutron fluence, and metallurgical factors (i.e. impurity contents) on the recovery of properties after the annealing of irradiated materials. Similar studies were continued to determine predictive methods for radiation embrittlement after repeated annealings. In May 1987 the first pilot annealing of a commercial reactor vessel (Novo-Voronezhskaya, III, NPP) was performed. The development of the annealing equipment and investigations performed to test the annealing process proved successful, and an improved safe operation for the reactor vessel was thus atttained providing for an extended service life. (orig.)

Introduction of neutron metrology for reactor radiation damage

International Nuclear Information System (INIS)

Alberman, A.; Genthon, J.P.; Schneider, W.; Wright, S.B.; Zijp, W.L.

1979-01-01

The background of the procedures for determining irradiation parameters which are of interest in radiation damage experiments is described. The first two chapters outline the concept of damage functions and damage models. The next two chapters give information on methods to determine neutron fluences and neutron spectra. The fifth chapter gives a review of correlation data available for graphite and steels. The last chapter gives guidance how to report the relevant irradiation parameters. Attention is given to the role of the neutron spectrum in deriving values for damage fluence, energy transferred to the lattice, and number of displacements

Effect of radiation damage on luminescence of erbium-implanted SiO sub 2 /Si studied by slow positron beam

CERN Document Server

Kawasuso, A; Hirata, K; Sekiguchi, T; Kobayashi, Y; Okada, S

2000-01-01

The effect of damage on 1.54 mu m luminescence for 30 keV-Er-implanted SiO sub 2 films has been studied by positron annihilation and cathodoluminescence. It was found that S-parameter in the films decreased after implantation, indicating the suppression of positronium formation. The luminescence appeared with the recovery of the S-parameter after 600 deg. C annealing. The intensity reached a maximum at 900 deg. C annealing whereas the S-parameter did not change significantly. It seems that most damages recover at 600 deg. C and thereafter Er ions transform to an optically active state at 900 deg. C.

X-radiation damage of hydrated lecithin membranes detected by real-time X-ray diffraction using wiggler-enhanced synchrotron radiation as the ionizing radiation source

International Nuclear Information System (INIS)

Caffrey, M.; Cornell Univ., Ithaca, NY

1984-01-01

Radiation damage of hydrated lecithin membranes brought about by exposure to wiggler-derived synchrotron radiation at 8.3 keV (1.5 A) is reported. Considerable damage was observed with exposures under 1 h at an incident flux density of 3 x 10 10 photons s -1 mm -2 , corresponding to a cumulative radiation dose of <= 10 MRad. Damage was so dramatic as to be initially observed while making real-time X-ray diffraction measurements on the sample. The damaging effects of 8.3 keV X-rays on dispersions of dipalmitoyllecithin and lecithin derived from hen egg yolk are as follows: (1) marked changes were noted in the X-ray diffraction behaviour, indicating disruption of membrane stacking. (2) Chemical breakdown of lecithin was observed. (3) The X-ray beam visibly damaged the sample and changed the appearance of the lipid dispersion, when viewed under the light microscope. Considering the importance of X-ray diffraction as a structural probe and the anticipated use of synchrotron radiation in studies involving membranes, the problem of radiation damage must be duly recognized. Furthermore, since dipalmitoyllecithin, the major lipid used in the present study, is a relatively stable compound, it is not unreasonable to expect that X-ray damage may be a problem with other less stable biological and non-biological materials. These results serve to emphasize that whenever a high intensity X-ray source is used, radiation damage can be a problem and that the sensitivity of the sample must always be evaluated under the conditions of measurement. (orig.)

Vessel annealing. Will it become a routine procedure?

International Nuclear Information System (INIS)

Davies, M.

1995-01-01

The effect of neutron radiation on the reactor pressure vessel and the influence of annealing performed to eliminate this effect are explained. Some practical examples are given. A simple heat treatment at 450 degC for 168 h is sufficient to eliminate a major fraction of the radiation effect in the displacement of the transition temperature from the brittle state to the tough state. Some observations indicate that at this temperature, excessive energy recovery takes place at the upper toughness limit in the Charpy diagram. The annealing furnace manufactured by the SKODA company is described. The furnace consists of heating elements in 13 zones and 5 heating sections. The maximum power of each element is 75 kW, the total power of the furnace is 975 kW. The annealing procedure and its results are briefly outlined for the reactor pressure vessel at unit 2 of the Jaslovske Bohunice NPP. Reactor pressure vessel annealing is proposed for the Marble Hill NPP which has been shut down. Preparatory activities for annealing are also under way at the Loviisa NPP. (J.B.)

Role of endothelium in radiation-induced normal tissue damages

International Nuclear Information System (INIS)

Milliat, F.

2007-05-01

More than half of cancers are treated with radiation therapy alone or in combination with surgery and/or chemotherapy. The goal of radiation therapy is to deliver enough ionising radiation to destroy cancer cells without exceeding the level that the surrounding healthy cells can tolerate. Unfortunately, radiation-induced normal tissue injury is still a dose limiting factor in the treatment of cancer with radiotherapy. The knowledge of normal tissue radiobiology is needed to determine molecular mechanisms involved in normal tissue pathogenic pathways in order to identify therapeutic targets and develop strategies to prevent and /or reduce side effects of radiation therapy. The endothelium is known to play a critical role in radiation-induced injury. Our work shows that endothelial cells promote vascular smooth muscle cell proliferation, migration and fibro-genic phenotype after irradiation. Moreover, we demonstrate for the first time the importance of PAI-1 in radiation-induced normal tissue damage suggesting that PAI-1 may represent a molecular target to limit injury following radiotherapy. We describe a new role for the TGF-b/Smad pathway in the pathogenesis of radiation-induced damages. TGF-b/Smad pathway is involved in the fibro-genic phenotype of VSMC induced by irradiated EC as well as in the radiation-induced PAI-1 expression in endothelial cells. (author)

Radiation Damage and Fission Product Release in Zirconium Nitride

Energy Technology Data Exchange (ETDEWEB)

Egeland, Gerald W. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

2005-08-29

Zirconium nitride is a material of interest to the AFCI program due to some of its particular properties, such as its high melting point, strength and thermal conductivity. It is to be used as an inert matrix or diluent with a nuclear fuel based on transuranics. As such, it must sustain not only high temperatures, but also continuous irradiation from fission and decay products. This study addresses the issues of irradiation damage and fission product retention in zirconium nitride through an assessment of defects that are produced, how they react, and how predictions can be made as to the overall lifespan of the complete nuclear fuel package. Ion irradiation experiments are a standard method for producing radiation damage to a surface for observation. Cryogenic irradiations are performed to produce the maximum accumulation of defects, while elevated temperature irradiations may be used to allow defects to migrate and react to form clusters and loops. Cross-sectional transmission electron microscopy and grazing-incidence x-ray diffractometry were used in evaluating the effects that irradiation has on the crystal structure and microstructure of the material. Other techniques were employed to evaluate physical effects, such as nanoindentation and helium release measurements. Results of the irradiations showed that, at cryogenic temperatures, ZrN withstood over 200 displacements per atom without amorphization. No significant change to the lattice or microstructure was observed. At elevated temperatures, the large amount of damage showed mobility, but did not anneal significantly. Defect clustering was possibly observed, yet the size was too small to evaluate, and bubble formation was not observed. Defects, specifically nitrogen vacancies, affect the mechanical behavior of ZrN dramatically. Current and previous work on dislocations shows a distinct change in slip plane, which is evidence of the bonding characteristics. The stacking-fault energy changes dramatically with

Radiation damage studies of the FeNi alloys, pure and with impurities, by measuring magnetic properties

International Nuclear Information System (INIS)

Sciani, Valdir

1978-01-01

Radiation damage studies are interesting from various points of view, but they have two main aspects, fundamental and technological. The void formations in metals and alloys during irradiation with high energy particles is a problem of interest in Nuclear Technology. The supersaturation of vacancies is one condition for a void formation, which results in swelling as well as in changes of mechanical, electrical and magnetic properties of materials used in power reactor. Isothermal and linear annealings have been performed before, during and after irradiation with neutrons from the IEAR-1 reactor, between 400 and 500 deg C in argon atmosphere. The samples used have a following nominal compositions: Fe Ni (50 - 50% at); FeNiMo ( 50 - 50% at + 50 ppm); FeNiCr ( 49,95 - 49,95 - 0,1% at); FeNiCr (49,75 - 49,75 - 0,5% at). The initial permeability disaccommodation has been followed by Magnetic After Effect (MAE) Method, which permitted the determination of the time constants, activation energies and Curie points. From these parameters it was possible to evaluate the super saturation of vacancies, showing that the MAE can be used as practical method for the election of nuclear materials without attaining high fluences. Some observations have been performed for the sample FeNiCr (49,75 - 49,75 - 0,5% at), which showed pronounced anomalies in the initial permeability during linear annealing.(author)

Radiation hardness tests of SiPMs for the JLab Hall D Barrel calorimeter

International Nuclear Information System (INIS)

Qiang, Yi; Zorn, Carl; Barbosa, Fernando; Smith, Elton

2013-01-01

We report on the measurement of the neutron radiation hardness of silicon photomultipliers (SiPMs) manufactured by Hamamatsu Corporation in Japan and SensL in Ireland. Samples from both companies were irradiated by neutrons created by a 1 GeV electron beam hitting a thin lead target at Jefferson Lab Hall A. More tests regarding the temperature dependence of the neutron radiation damage and self-annealing were performed on Hamamatsu SiPMs using a calibrated Am–Be neutron source from the Jefferson Lab Radiation Control group. As the result of irradiation both dark current and dark rate increase linearly as a function of the 1 MeV equivalent neutron fluence and a temperature dependent self-annealing effect is observed.

Radiation damage resistance in mercuric iodide X-ray detectors

Energy Technology Data Exchange (ETDEWEB)

Patt, B E; Dolin, R C; Devore, T M; Markakis, J M [EG and G Energy Measurements, Inc., Goleta, CA (USA); Iwanczyk, J S; Dorri, N [Xsirius, Inc., Marina del Rey, CA (USA); Trombka, J [National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center

1990-12-20

Mercuric iodide (HgI{sub 2}) radiation detectors show great potential as ambient-temperature solid-state detectors for X-rays, gamma rays and visible light, with parameters that are competitive with existing technologies. In a previous experiment, HgI{sub 2} detectors irradiated with 10 MeV protons/cm{sup 2} exhibited no damage. The 10 MeV protons represent only the low range of the spectrum of energies that are important. An experiment has been conducted at the Saturne accelerator facility at Saclay, France, to determine the susceptibility of these detectors to radiation damage by high-energy (1.5 GeV) protons. The detectors were irradiated to a fluence of 10{sup 8} protons/cm{sup 2}. This fluence is equivalent to the cosmic radiation expected in a one-year period in space. The resolution of the detectors was measured as a function of the integral dose. No degradation in the response of any of the detectors or spectrometers was seen. It is clear from this data that HgI{sub 2} has extremely high radiation-damage resistance, exceeding that of most other semiconductor materials used for radiation detectors. Based on the results shown to date, HgI{sub 2} detectors are suitable for applications in which they may be exposed to high integral dose levels. (orig.).

Issues of damage estimation under radiation emergency situation

International Nuclear Information System (INIS)

Volobuev, P.V.; Kozlova, N.I.

2005-01-01

The specificity of social, economical and ecological consequences of major radiation emergency situation is considered in the paper. The definitions and structure of direct and indirect damage under radiation emergency situation are given. The priority components of immediate expenses and those of long-term living on the contaminated territories are considered in the paper. (author)

Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

Science.gov (United States)

Benkő, Klára; Pintye, Éva; Szabó, Boglárka; Géresi, Krisztina; Megyeri, Attila; Benkő, Ilona

2008-12-01

To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of γ—irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD50 values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

International Nuclear Information System (INIS)

Benko', Klara; Pintye, Eva; Szabo, Boglarka; Geresi, Krisztina; Megyeri, Attila; Benko, Ilona

2008-01-01

To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of γ--irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD 50 values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

Ionizing radiation, antioxidant response and oxidative damage: A meta-analysis.

Science.gov (United States)

Einor, D; Bonisoli-Alquati, A; Costantini, D; Mousseau, T A; Møller, A P

2016-04-01

One mechanism proposed as a link between exposure to ionizing radiation and detrimental effects on organisms is oxidative damage. To test this hypothesis, we surveyed the scientific literature on the effects of chronic low-dose ionizing radiation (LDIR) on antioxidant responses and oxidative damage. We found 40 publications and 212 effect sizes for antioxidant responses and 288 effect sizes for effects of oxidative damage. We performed a meta-analysis of signed and unsigned effect sizes. We found large unsigned effects for both categories (0.918 for oxidative damage; 0.973 for antioxidant response). Mean signed effect size weighted by sample size was 0.276 for oxidative damage and -0.350 for antioxidant defenses, with significant heterogeneity among effects for both categories, implying that ionizing radiation caused small to intermediate increases in oxidative damage and small to intermediate decreases in antioxidant defenses. Our estimates are robust, as shown by very high fail-safe numbers. Species, biological matrix (tissue, blood, sperm) and age predicted the magnitude of effects for oxidative damage as well as antioxidant response. Meta-regression models showed that effect sizes for oxidative damage varied among species and age classes, while effect sizes for antioxidant responses varied among species and biological matrices. Our results are consistent with the description of mechanisms underlying pathological effects of chronic exposure to LDIR. Our results also highlight the importance of resistance to oxidative stress as one possible mechanism associated with variation in species responses to LDIR-contaminated areas. Copyright © 2016 Elsevier B.V. All rights reserved.

Radiation damage to histones

International Nuclear Information System (INIS)

Mee, L.K.; Adelstein, S.J.

1985-01-01

The damage to histones irradiated in isolation is being elaborated to aid the identification of the crosslinking sites in radiation-induced DNA-histone adducts. Histones are being examined by amino acid analysis to determine the destruction of residues and by polyacrylamide gel electrophoresis to delineate changes in conformation. For the slightly lysine-rich histone, H2A, a specific attack on selective residues has been established, the aromatic residues, tyrosine and phenylalanine, and the heterocyclic residue, histidine, being significantly destroyed. In addition, a significant increase in aspartic acid was found; this may represent a radiation product from scission of the ring in the histidine residues. The similarity of the effects on residues in nitrous oxide-saturated and nitrogen-saturated solutions suggests that OH . and e/sub aq//sup -/ are equally efficient and selective in their attack. On gel electrophoresis degradation of the histone H2A was found to be greatest for irradiations in nitrous oxide-saturated solutions, suggesting CH . is the most effective radical for producing changes in conformation; O/sub 2//sup -/ was essentially ineffective. Other histones are being examined for changes in amino acid composition, conformation, and for the formation of radiation products

Photoprotection beyond ultraviolet radiation--effective sun protection has to include protection against infrared A radiation-induced skin damage.

Science.gov (United States)

Schroeder, P; Calles, C; Benesova, T; Macaluso, F; Krutmann, J

2010-01-01

Solar radiation is well known to damage human skin, for example by causing premature skin ageing (i.e. photoageing). We have recently learned that this damage does not result from ultraviolet (UV) radiation alone, but also from longer wavelengths, in particular near-infrared radiation (IRA radiation, 760-1,440 nm). IRA radiation accounts for more than one third of the solar energy that reaches human skin. While infrared radiation of longer wavelengths (IRB and IRC) does not penetrate deeply into the skin, more than 65% of the shorter wavelength (IRA) reaches the dermis. IRA radiation has been demonstrated to alter the collagen equilibrium of the dermal extracellular matrix in at least two ways: (a) by leading to an increased expression of the collagen-degrading enzyme matrix metalloproteinase 1, and (b) by decreasing the de novo synthesis of the collagen itself. IRA radiation exposure therefore induces similar biological effects to UV radiation, but the underlying mechanisms are substantially different, specifically, the cellular response to IRA irradiation involves the mitochondrial electron transport chain. Effective sun protection requires specific strategies to prevent IRA radiation-induced skin damage. 2010 S. Karger AG, Basel.

PLEPS study of thermal annealing influence on binary Fe-11.62 % Cr alloys

International Nuclear Information System (INIS)

Sojak, S.; Slugen, V.; Petriska, V.; Stancek, S.; Vitazek, K.; Stacho, M.; Veternikova, J.; Sabelova, V.; Krsjak, V.; Egger, W.; Ravelli, L.; Skarba, M.; Priputen, P.

2012-01-01

Lifetime of structural materials is one of the crucial factors for operation of nuclear power plants (NPP). Therefore, high expectations and requirements are put on these materials from the radiation, heat and mechanical resistance point of view. Even higher stresses are expected in new generations of nuclear power plants, such as Generation IV and fusion reactors. Therefore, investigation of new structural materials is among others focused on study of reduced activation ferritic/martensitic (RAFM) steels with good characteristics as lower activation, good resistance to volume swelling, good radiation, and heat resistance (up to 550 grad C). Our research is focused on study of radiation damage simulated by ion implantations and thermal treatment evaluation of RAFM steels in form of binary Fe-Cr model alloys. Due to the defect production by ions, there was applied an approach for restoration of initial physical and mechanical characteristics of structural materials in the form of thermal annealing, with goal to decrease size and amount of accumulated defects. Experimental analysis of material damage at microstructural level was performed by Pulsed Low Energy Positron System (PLEPS) at the high intensity positron source NEPOMUC at the Munich research reactor FRM-II. (authors)

Consequential late radiation damage in the skin in nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Li Wei; Kong Ling; Zhang Youwang; Hu Chaosu; Wu Yongru

2008-01-01

Objective: To evaluate the relationship between early and late radiation damage in skin. Methods: 335 patients with nasopharyngeal carcinoma treated with radical radiotherapy were evaluated. 240 patients had lymph nodes in the neck at initial diagnosis. The median doses were 70 Gy (55-86 Gy) to the nasopharyngeal region by external beam radiotherapy. The median doses were 64 Gy (46-72 Gy) to the neck with lymph node metastases, 55 Gy (21-67 Gy) to the node-negative neck. 71 patients were treated with facial-neck fields, while 264 patients were treated with pre-auricular fields. Chemotherapy was given in 48 patients. According to the 1995 SOMA scales late radiation damage in the skin was evaluated. Results: The median time from the radiotherapy to follow up was 14 years (range, 5-38 years). 63 patients have grade 0 late radiation reactions in the neck skin, the grade 1,2, 3,4 late radiation reactions in the neck skin were 43.9% (147 patients), 20.9% (70 patients), 13.7% (46 patients) and 2.7% (9 patients), respectively. 44 patients had moist desquamation in the medical records. The grade 1,2,3,4 late radiation reactions in the neck skin were 41%, 23%, 30% and 5%, respectively in patients with moist desquamation, while in patients without moist desquamation, the corresponding rates were 44.3%, 20.6%, 11.3% and 2.4%, respectively. The difference were significant between these two groups by chi-square analysis(χ 2 =17.42, P=0.002). Furthermore, whether patients had positive lymph node in the neck or not, the size of facial-neck fields and higher doses to the neck had more severe late radiation reaction in the neck skin, while age, gender and chemotherapy failed to show any effects on the development of late radiation reactions in the neck skin. Conclusion: The severe early radiation damage in the skin possibly increases the late radiation damage in the neck skin. (authors)

Nonuniform radiation damage in permanent magnet quadrupoles.

Science.gov (United States)

Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

2014-08-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Nonuniform radiation damage in permanent magnet quadrupoles

International Nuclear Information System (INIS)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

2014-01-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Damage of DNA by radiation and it's recovery, 3

International Nuclear Information System (INIS)

Narita, Noboru; Matsuura, Tomio; Sato, Hiroyuki.

1974-01-01

The damage and recovery of DNA was investigated by the incorporation of thymine derivatives (DHT, I trans, II trans, cis and glycol) into exponentially growing Tetrahymena cells. The strain employed was Tetrahymena pyriformis, Variety I, mating type IV. It is well known that these thymine derivatives are induced in vivo by radiation. The in vivo damage of DNA induced by radiation, and its recovery, were confirmed experimentally by means of gradient separation of sucrose density and by analytical ultra centrifugation (UVC). The recovery of DNA, its excision repair and its recombinational repair were compared with the recovery of Bacillus subtilis whose recovery kinetics were already known. 1) The damage of DNA was more sensitive to glycol than to II trans and cis. On the other hand, DHT is not sensitive for breaking DNA strand. 2) In its recovery damaged DNA was no more sensitive to glycol than to hhp as was true for Bacillus subtilis. (author)

Genomic damage in children accidentally exposed to ionizing radiation

DEFF Research Database (Denmark)

Fucic, A; Brunborg, G; Lasan, R

2007-01-01

During the last decade, our knowledge of the mechanisms by which children respond to exposures to physical and chemical agents present in the environment, has significantly increased. Results of recent projects and programmes focused on children's health underline a specific vulnerability of chil...... and efficient preventive measures, by means of a better knowledge of the early and delayed health effects in children resulting from radiation exposure....... of children to environmental genotoxicants. Environmental research on children predominantly investigates the health effects of air pollution while effects from radiation exposure deserve more attention. The main sources of knowledge on genome damage of children exposed to radiation are studies performed...... after the Chernobyl nuclear plant accident in 1986. The present review presents and discusses data collected from papers analyzing genome damage in children environmentally exposed to ionizing radiation. Overall, the evidence from the studies conducted following the Chernobyl accident, nuclear tests...

Microstructural evolution of radiation induced defects in ZnO during isochronal annealing

International Nuclear Information System (INIS)

Brunner, S.; Puff, W.; Balogh, A.G.

1999-01-01

In this study the authors discuss the microstructural changes after electron and proton irradiation and the thermal evolution of the radiation induced defects during isochronal annealing. The nominally undoped samples were irradiated either with 3 MeV protons to a fluence of 1.2 x 10 18 p/cm 2 or with 1 MeV electrons to a fluence of 1 x 10 18 e/cm 2 . The investigation was performed with positron lifetime and Doppler-Broadening measurements. The measurements were done at room temperature and in some cases down to 10 K to investigate the thermal dependence of the trapping characteristics of the positrons

Combined effects of displacement damage and high gas content in aluminum

International Nuclear Information System (INIS)

Farrell, K.; Houston, J.T.

1976-01-01

A solid solution alloy of 2300 at. ppM of 6 Li isotope in aluminum was neutron irradiated at about 0.36 T/sub m/ in high, fast and thermal fluxes producing a damage level of 2 to 3 dpa and simultaneously inducing a gas content of about 2200 at. ppM each of helium and tritium from burnup of 6 Li. The gases significantly increased the nucleation of structural defects but did not change the degree of swelling; cavity concentrations were increased approximately 1000-fold, cavity sizes were decreased approximately 10-fold and there was approximately 10-fold increase in the concentrations of dislocations. Also, large cavities were developed on grain boundaries. The cavities were consistent with their being gas-filled bubbles. The refinement of damage structure by the gases caused a considerable increase in radiation hardening. Bend tests at 77 and 296 0 K revealed severe embrittlement and intergranular fracture. Comparison with data from material irradiated to produce comparable gas levels but relatively little displacement damage indicates that premature intergranular failure is much enhanced by the presence of a defect-hardened matrix. Postirradiation annealing tests showed the cavity and dislocation structures to have high resistance to annealing. Annealing also encouraged the development of a secondary population of large cavities believed to be associated with migration and precipitation of tritium

Combined effects of displacement damage and high gas content in aluminum

International Nuclear Information System (INIS)

Farrell, K.; Houston, J.T.

1976-05-01

A solid solution alloy of 2300 appm of 6 Li isotope in aluminum was neutron irradiated at about 0.36 T/sub m/ in high, fast and thermal fluxes producing a damage level of 2 to 3 dpa and simultaneously inducing a gas content of about 2200 appm each of helium and tritium from burnup of 6 Li. The gases significantly increased the nucleation of structural defects but did not change the degree of swelling; cavity concentrations were increased approximately 1000-fold, cavity sizes were decreased approximately 10-fold and there was approximately 10-fold increase in the concentrations of dislocations. Also, large cavities were developed on grain boundaries. The cavities were consistent with their being gas-filled bubbles. The refinement of damage structure by the gases caused a considerable increase in radiation hardening. Bend tests at 77 and 296 K revealed severe embrittlement and intergranular fracture. Comparison with data from material irradiated to produce comparable gas levels but relatively little displacement damage indicates that premature intergranular failure is much enhanced by the presence of a defect-hardened matrix. Postirradiation annealing tests showed the cavity and dislocation structures to have high resistance to annealing. Annealing also encouraged the development of a secondary population of large cavities believed to be associated with migration and precipitation of tritium

Radio-oxidative membrane damage and its possible role as an indicator of radiation exposure

International Nuclear Information System (INIS)

Amit Kumar; Pandey, B.N.; Mishra, K.P.

2004-01-01

Cellular membranes have been recognized as a sensitive target in the mechanism of ionizing radiation-induced cell killing. In our laboratory, studies have been devoted to investigations on gamma radiation induced oxidative damage to model and cellular membrane damage by employing fluorescence and electron spin resonance (ESR) methods Considerable evidences has accumulated to suggest that radiation induced oxidative damage was related to apoptotic death of a variety of cells in culture. Radiation induced damage involving lipid peroxidation, altered bilayer fluidity, permeability changes and intracellular generated ROS have been evaluated by chemical and physical methods. Modification of damage by structural modulating agents such as cholesterol and antioxidants such as eugenol, ascorbic acid, ellagic acid, triphala have been extensively investigated. Generation of intracellular ROS in radiation stressed normal cell e.g. mouse thymocytes, tumor cells e.g. Ehrlich ascites cells and human cervical cell line were evaluated after exposure from low to moderate doses of α-radiation. Results suggest that modulation of intracellular ROS level may be an important approach to alter radio-cytotoxicity of cells. This presentation would describe results of our study together with an overview of free radical mediated oxidative damage to cellular membrane as an indicator of radiation exposure. (author)

Complex DNA Damage: A Route to Radiation-Induced Genomic Instability and Carcinogenesis

Directory of Open Access Journals (Sweden)

Ifigeneia V. Mavragani

2017-07-01

Full Text Available Cellular effects of ionizing radiation (IR are of great variety and level, but they are mainly damaging since radiation can perturb all important components of the cell, from the membrane to the nucleus, due to alteration of different biological molecules ranging from lipids to proteins or DNA. Regarding DNA damage, which is the main focus of this review, as well as its repair, all current knowledge indicates that IR-induced DNA damage is always more complex than the corresponding endogenous damage resulting from endogenous oxidative stress. Specifically, it is expected that IR will create clusters of damage comprised of a diversity of DNA lesions like double strand breaks (DSBs, single strand breaks (SSBs and base lesions within a short DNA region of up to 15–20 bp. Recent data from our groups and others support two main notions, that these damaged clusters are: (1 repair resistant, increasing genomic instability (GI and malignant transformation and (2 can be considered as persistent “danger” signals promoting chronic inflammation and immune response, causing detrimental effects to the organism (like radiation toxicity. Last but not least, the paradigm shift for the role of radiation-induced systemic effects is also incorporated in this picture of IR-effects and consequences of complex DNA damage induction and its erroneous repair.

Conformational variation of proteins at room temperature is not dominated by radiation damage

International Nuclear Information System (INIS)

Russi, Silvia; González, Ana; Kenner, Lillian R.; Keedy, Daniel A.; Fraser, James S.; Bedem, Henry van den

2017-01-01

Protein crystallography data collection at synchrotrons is routinely carried out at cryogenic temperatures to mitigate radiation damage. Although damage still takes place at 100 K and below, the immobilization of free radicals increases the lifetime of the crystals by approximately 100-fold. Recent studies have shown that flash-cooling decreases the heterogeneity of the conformational ensemble and can hide important functional mechanisms from observation. These discoveries have motivated increasing numbers of experiments to be carried out at room temperature. However, the trade-offs between increased risk of radiation damage and increased observation of alternative conformations at room temperature relative to cryogenic temperature have not been examined. A considerable amount of effort has previously been spent studying radiation damage at cryo-temperatures, but the relevance of these studies to room temperature diffraction is not well understood. Here, the effects of radiation damage on the conformational landscapes of three different proteins (T. danielli thaumatin, hen egg-white lysozyme and human cyclophilin A) at room (278 K) and cryogenic (100 K) temperatures are investigated. Increasingly damaged datasets were collected at each temperature, up to a maximum dose of the order of 10 7 Gy at 100 K and 10 5 Gy at 278 K. Although it was not possible to discern a clear trend between damage and multiple conformations at either temperature, it was observed that disorder, monitored by B-factor-dependent crystallographic order parameters, increased with higher absorbed dose for the three proteins at 100 K. At 278 K, however, the total increase in this disorder was only statistically significant for thaumatin. A correlation between specific radiation damage affecting side chains and the amount of disorder was not observed. Lastly, this analysis suggests that elevated conformational heterogeneity in crystal structures at room temperature is observed despite radiation

Design of offline measuring system for radiation damage effects on linear CCD

International Nuclear Information System (INIS)

Zhang Yong; Tang Benqi; Xiao Zhigang; Wang Zujun; Huang Fang; Huang Shaoyan

2004-01-01

The paper discusses the hardware design of offline measuring system for radiation damage effects on linear CCD. Some credible results were achieved by using this system. The test results indicate that the system is available for the study of the radiation damage effects on linear CCD. (authors)

Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation

Science.gov (United States)

Sutherland, Betsy M.; Bennett, Paula V.; Cintron-Torres, Nela; Hada, Megumi; Trunk, John; Monteleone, Denise; Sutherland, John C.; Laval, Jacques; Stanislaus, Marisha; Gewirtz, Alan

2002-01-01

Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.

Quantitative damage depth profiles in arsenic implanted HgCdTe

Energy Technology Data Exchange (ETDEWEB)

Lobre, C., E-mail: clement.lobre@cea.fr [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jalabert, D. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Vickridge, I.; Briand, E.; Benzeggouta, D. [Institut des NanoSciences de Paris, UMR 7588 du CNRS, Universite de Pierre et Marie Curie, Paris (France); Mollard, L. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jouneau, P.H. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Ballet, P. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)

2013-10-15

Rutherford backscattering experiments under channeling conditions (RBS-c) have been carried out on Hg{sub 0.77}Cd{sub 0.23}Te (MCT) layers implanted with arsenic. Accurate damage profiles have been extracted through a simple formalism for implanted and annealed layers. Quantitative damage profiles are correlated with structural defects observed by bright-field scanning transmission electron microscopy (BF-STEM) and chemical composition measured by secondary ion mass spectrometry (SIMS). Evolution of damage for increasing ion implantation fluence has been investigated by these three complementary techniques. Evidence is found of irradiation induced annealing during implantation. A fast damage recovery has been observed for post-implantation thermal anneals. In the case of an implanted layer annealed during 1 h, the damage profile, associated with arsenic concentration measurements, indicates the presence of complexes involving arsenic.

Quantitative damage depth profiles in arsenic implanted HgCdTe

International Nuclear Information System (INIS)

Lobre, C.; Jalabert, D.; Vickridge, I.; Briand, E.; Benzeggouta, D.; Mollard, L.; Jouneau, P.H.; Ballet, P.

2013-01-01

Rutherford backscattering experiments under channeling conditions (RBS-c) have been carried out on Hg 0.77 Cd 0.23 Te (MCT) layers implanted with arsenic. Accurate damage profiles have been extracted through a simple formalism for implanted and annealed layers. Quantitative damage profiles are correlated with structural defects observed by bright-field scanning transmission electron microscopy (BF-STEM) and chemical composition measured by secondary ion mass spectrometry (SIMS). Evolution of damage for increasing ion implantation fluence has been investigated by these three complementary techniques. Evidence is found of irradiation induced annealing during implantation. A fast damage recovery has been observed for post-implantation thermal anneals. In the case of an implanted layer annealed during 1 h, the damage profile, associated with arsenic concentration measurements, indicates the presence of complexes involving arsenic

Relation of radiation damage of metallic solids to electronic structure. Pt. 5

International Nuclear Information System (INIS)

Shalaev, A.M.; Adamenko, A.A.

1977-01-01

The problem of relating a damage in metal solids to the parameters of radiation fluxes and the physical nature of a target is considered. Basing upon experimental and theoretical investigations into the processes of interaction of particle fluxes with solids, the following conclusions have been reached. Threshold energy of ion displacement in the crystal lattice of a metal solid is dependent on the energy of a bombarding particle, which is due to ionization and electroexcitation stimulated by energy transfer from a fast particle to a system of collectivized electrons. The rate of metal solid damage by radiation depends on the state of the crystal lattice, in particular on its defectness. Variations of local electron density in the vicinity of a defect are related with changing thermodynamic characteristics of radiation-induced defect formation. A type of atomic bond in a solid affects the rate of radiation damage. The greatest damage occurs in materials with a covalent bond

Radiation damage: special reference to gas filled radiation detectors

International Nuclear Information System (INIS)

Gaur, Sudha; Joshi, Pankaj Kumar; Rathore, Shakuntla

2012-01-01

Radiation damage is a term associated with ionizing radiation. In gas filled particle detectors, radiation damage to gases plays an important role in the device's ageing, especially in devices exposed to high intensity radiation, e.g. detector for the large hadrons collide. Ionization processes require energy above 10 eV, while splitting covalent bond in molecules and generating free radical require only 3-4 eV. The electrical discharges initiated by the ionization event by the particles result in plasma populated by large amount of free radical. The highly reactive free radical can recombine back to original molecules, or initiate a chain of free radical polymerization reaction with other molecules, yielding compounds with increasing molecular weight. These high molecular weight compounds then precipitate from gases phase, forming conductive or non-conductive deposits on the electrodes an insulating surfaces of the detector and distorting it's response. Gases containing hydrocarbon quenchers, e.g. argon-methane, are typically sensitive to ageing by polymerization; addition of oxygen tends to lower the ageing rates. Trace amount of silicon oils, present form out gassing of silicon elastomers and especially from traces of silicon lubricant tend to decompose and form deposits of silicon crystals on the surfaces. Gases mixture of argon (or xenon) with CO 2 and optimally also with 2-3 % of oxygen are highly tolerant to high radiation fluxes. The oxygen is added as noble gas with CO 2 has too high transparency for high energy photons; ozone formed from the oxygen is a strong absorber of ultra violet photons. Carbon tetra fluoride can be used as a component of the gas for high-rate detectors; the fluorine radical produced during the operation however limit the choice of materials for the chambers and electrodes (e.g. gold electrodes are required, as the fluorine radicals attack metals, forming fluorides). Addition of carbon tetra fluoride can however eliminate the

Radiation damage of pixelated photon detector by neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Isamu [KEK, 1-1 Oho Tsukuba 305-0801 (Japan)], E-mail: isamu.nakamura@kek.jp

2009-10-21

Radiation Damage of Pixelated Photon Detector by neutron irradiation is reported. MPPC, one of PPD or Geiger-mode APD, developed by Hamamatsu Photonics, is planned to be used in many high energy physics experiments. In such experiments radiation damage is a serious issue. A series of neutron irradiation tests is performed at the Reactor YAYOI of the University of Tokyo. MPPCs were irradiated at the reactor up to 10{sup 12}neutron/cm{sup 2}. In this paper, the effect of neutron irradiation on the basic characteristics of PPD including gain, noise rate, photon detection efficiency is presented.

Study of radiation damage in solid materials by simulating physical processes

International Nuclear Information System (INIS)

Pinnera Hernandez, Ibrahin

2006-12-01

Nowadays the damage induced by different types of radiation in advanced materials is widely studied. Especially those materials involved in experiments and developing of new technologies, such as high critical temperature superconductors, semiconductors, metals. These materials are the basis constituents of radiation detectors, particle accelerators, etc. One way of studying this kind of damage is through the determination of the displacements per atom (dpa) induced by the radiation in these materials. This magnitude is one of the measures of the provoked radiation damage. On this direction, the present thesis deals with the study of two types of materials through mathematical simulation of physical processes taking place in the radiation transport. Ceramic superconductor Yba 2 Cu 3 O 7-x and metal Fe are the selected materials. The energy range of the incident gamma radiation goes from a few keV to 15 MeV. The MCNPX version 2.6b is used to determine the physical magnitudes required to calculate the distribution of displacements per atom within these materials, using an algorithm implemented for this purpose. Finally, a comparison between the obtained dpa profiles and the corresponding of energy deposition by radiation in these same materials and the possible linear dependence between both quantities is discussed. (Author)

Processing of radiation-induced clustered DNA damage generates DSB in mammalian cells

International Nuclear Information System (INIS)

Gulston, M.K.; De Lara, C.M.; Davis, E.L.; Jenner, T.J.; O'Neill, P.

2003-01-01

Full text: Clustered DNA damage sites, in which two or more lesions are formed within a few helical turns of the DNA after passage of a single radiation track, are signatures of DNA modifications induced by ionizing radiation in mammalian cell. With 60 Co-radiation, the abundance of clustered DNA damage induced in CHO cells is ∼4x that of prompt double strand breaks (DSB) determined by PFGE. Less is known about the processing of non-DSB clustered DNA damage induced in cells. To optimize observation of any additional DSB formed during processing of DNA damage at 37 deg C, xrs-5 cells deficient in non-homologous end joining were used. Surprisingly, ∼30% of the DSB induced by irradiation at 37 deg C are rejoined within 4 minutes in both mutant and wild type cells. No significant mis-repair of these apparent DSB was observed. It is suggested that a class of non-DSB clustered DNA damage is formed which repair correctly within 4 min but, if 'trapped' prior to repair, are converted into DSB during the lysis procedure of PFGE. However at longer times, a proportion of non-DSB clustered DNA damage sites induced by γ-radiation are converted into DSB within ∼30 min following post-irradiation incubation at 37 deg C. The corresponding formation of additional DSB was not apparent in wild type CHO cells. From these observations, it is estimated that only ∼10% of the total yield of non DSB clustered DNA damage sites are converted into DSB through cellular processing. The biological consequences that the majority of non-DSB clustered DNA damage sites are not converted into DSBs may be significant even at low doses, since a finite chance exists of these clusters being formed in a cell by a single radiation track

Radiation damage at LHCb, results and expectations

CERN Multimedia

Faerber, Christian

2011-01-01

The LHCb Detector is a single-arm spectrometer at the LHC designed to detect new physics through measuring CP violation and rare decays of heavy flavor mesons. The detector consists of vertex detector, tracking system, dipole magnet, 2 RICH detectors, em. calorimeter, hadron calorimeter, muon detector which all use different technologies and suffer differently from radiation damage. These radiation damage results and the investigation methods will be shown. The delivered luminosity till July 2011 was about 450 pb−1. The Vertex detector receives the highest particle flux at LHCb. The currents drawn by the silicon sensors are, as expected, increasing proportional to the integrated luminosity. The highest irradiaton regions of the n-bulk silicon sensors are observed to have recently undergone space charge sign inversion. The Silicon Trackers show increasing leakage currents comparable with earlier predictions. The electromagentic calorimeter and hadron calorimeter suffer under percent-level signal decrease whi...

Defect production in simulated cascades: Cascade quenching and short-term annealing

International Nuclear Information System (INIS)

Heinisch, H.L.

1983-01-01

Defect production in displacement cascades in copper has been modeled using the MARLOWE code to generate cascades and the stochastic annealing code ALSOME to simulate cascade quenching and short-term annealing of isolated cascades. Quenching is accomplished by using exaggerated values for defect mobilities and for critical reaction distances in ALSOME for a very short time. The quenched cascades are then short-term annealed with normal parameter values. The quenching parameter values were empirically determined by comparison with results of resistivity measurements. Throughout the collisional, quenching and short-term annealing phases of cascade development, the high energy cascades continue to behave as a collection of independent lower energy lobes. For recoils above about 30 keV the total number of defects and the numbers of free defects scale with the damage energy. As the energy decreases from 30 keV, defect production varies with the changing nature of the cascade configuration, resulting in more defects per unit damage energy. The simulated annealing of a low fluence of interacting cascades revealed an interstitial shielding effect on depleted zones during Stage I recovery. (orig.)

Delayed repair of radiation induced clustered DNA damage: Friend or foe?

International Nuclear Information System (INIS)

Eccles, Laura J.; O'Neill, Peter; Lomax, Martine E.

2011-01-01

A signature of ionizing radiation exposure is the induction of DNA clustered damaged sites, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. Clustered damage is made up of double strand breaks (DSB) with associated base lesions or abasic (AP) sites, and non-DSB clusters comprised of base lesions, AP sites and single strand breaks. This review will concentrate on the experimental findings of the processing of non-DSB clustered damaged sites. It has been shown that non-DSB clustered damaged sites compromise the base excision repair pathway leading to the lifetime extension of the lesions within the cluster, compared to isolated lesions, thus the likelihood that the lesions persist to replication and induce mutation is increased. In addition certain non-DSB clustered damaged sites are processed within the cell to form additional DSB. The use of E. coli to demonstrate that clustering of DNA lesions is the major cause of the detrimental consequences of ionizing radiation is also discussed. The delayed repair of non-DSB clustered damaged sites in humans can be seen as a 'friend', leading to cell killing in tumour cells or as a 'foe', resulting in the formation of mutations and genetic instability in normal tissue.

Radiation induced crystallinity damage in poly(L-lactic acid)

CERN Document Server

Kantoglu, O

2002-01-01

The radiation-induced crystallinity damage in poly(L-lactic acid) (PLLA) in the presence of air and in vacuum, is studied. From the heat of fusion enthalpy values of gamma irradiated samples, some changes on the thermal properties were determined. To identify these changes, first the glass transition temperature (T sub g) of L-lactic acid polymers irradiated to various doses in air and vacuum have been investigated and it is found that it is independent of irradiation atmosphere and dose. The fraction of damaged units of PLLA per unit of absorbed energy has been measured. For this purpose, SAXS and differential scanning calorimetry methods were used, and the radiation yield of number of damaged units (G(-u)) is found to be 0.74 and 0.58 for PLLA samples irradiated in vacuum and air, respectively.

Radiation damage to DNA constituents

International Nuclear Information System (INIS)

Bergene, R.

1977-01-01

The molecular changes of the DNA molecule, in various systems exposed to inoizing radiation, have been the subject of a great number of studies. In the present work electron spin resonance spectroscopy (ESR) has been applied to irradiated crystalline systems, in particular single crystals of DNA subunits and their derivatives. The main conclusions about the molecular damage are based on this technique in combination with molecular orbital calculations. It should be emphasized that the ESR technique is restricted to damage containing unpaired electrons. These unstable intermediates called free radicals seem, however, to be involved in all molecular models describing the action of radiation on DNA. One of the premises for a detailed theory of the radiation induced reactions at the physico-chemical level seems to involve exact knowledge of the induced free radicals as well as the modes of their formation and fate. For DNA, as such, it is hardly possible to arrive at such a level of knowledge since the molecular complexity prevents selective studies of the many different radiation induced products. One possible approach is to study the free radicals formed in the constituents of DNA. In the present work three lines of approach should be mentioned. The first is based on the observation that radical formation in general causes only minor structural alterations to the molecule in question. The use of isotopes with different spin and magnetic moment (in particular deuterium) may also serve a source of information. Deuteration leads to a number of protons, mainly NH - and OH, becoming substituted, and if any of these are involved in interactions with unpaired protons the resonance pattern is influeneed. The third source of information is molecular orbital calculation. The electron spin density distribution is a function in the three dimensional space based on the system's electronic wave functions. This constitutes the basis for the idea that ESR data can be correlated with

Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage

International Nuclear Information System (INIS)

Stapleton, A.E.; Walbot, V.

1994-01-01

Diverse flavonoid compounds are widely distributed in angiosperm families. Flavonoids absorb radiation in the ultraviolet (UV) region of the spectrum, and it has been proposed that these compounds function as UV filters. We demonstrate that the DNA in Zea mays plants that contain flavonoids (primarily anthocyanins) is protected from the induction of damage caused by UV radiation relative to the DNA in plants that are genetically deficient in these compounds. DNA damage was measured with a sensitive and simple assay using individual monoclonal antibodies, one specific for cyclobutane pyrimidine dimer damage and the other specific for pyrimidine(6,4)pyrimidone damage. (author)

Effect of Mercuric Nitrate on Repair of Radiation-induced DNA Damage

Energy Technology Data Exchange (ETDEWEB)

Paneka, Agnieszka; Antonina, Cebulska Wasilewska [The Henryk Niewodniczanski Institute of Nuclear Physics, Krakow (Poland); Han, Min; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2009-10-15

High concentrations of mercury can cause serious damage to the nervous system, immune system, kidneys and liver in humans. And mercury is toxic to developing embryos because mercury ions can penetrate the blood.placenta barrier to reach the embryo. Studies from human monitoring of occupational exposure to mercury vapours have shown that mercury can alter the ability of lymphocytes to repair radiation-induced DNA damage. The aim of this in vitro study was to investigate, on the molecular and cytogenetic levels, the effect of exposure to mercury ions on the kinetics of the repair process of DNA damage induced by ionising radiation.

Multiscale approach to the physics of radiation damage with ions

Energy Technology Data Exchange (ETDEWEB)

Surdutovich, Eugene [Physics Department, Oakland University, 2200 N. Squirrel Rd., Rochester MI 48309 (United States); Solov' yov, Andrey V. [Frankfurt Institute for Advanced Studies, Goethe University, Ruth-Moufang-Str. 1, Frankfurt am Main 60438 (Germany)

2013-04-19

We review a multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales. We briefly overview its history and present the current stage of its development. The differences of the multiscale approach from other methods of understanding and assessment of radiation damage are discussed as well as its relationship to other branches of physics, chemistry and biology.

Radiation damage studies on the optical and mechanical properties of plastic scintillators

International Nuclear Information System (INIS)

Mizue Hamada, Margarida; Roberto Rela, Paulo; Eduardo da Costa, Fabio; Henrique de Mesquita, Carlos

1999-01-01

This paper describes the radiation damage studies on a large volume plastic scintillator based in polystyrene doped with PPO and POPOP. The consequences on their mechanical and scintillation properties were evaluated before and after irradiation with different dose rates of 60 Co gamma radiation, in several doses. The optical results show a significant difference in the radiation susceptibility, when the plastic scintillator is irradiated at low rate (0.1 kGy/h) with that irradiated at high dose rate (85 kGy/h). The losses in the optical and mechanical properties increase as the irradiation dose is increased. The damage evaluated by the transmittance, emission intensity, pulse height and tensile strength was normalized as a damage fraction and fitted by a bi-exponential function. It was observed that the damage for irradiation is not permanent and it obeys a bi-exponential function

Radiation damage studies for the D0 silicon detector

International Nuclear Information System (INIS)

Lehner, F.

2004-01-01

We report on irradiation studies performed on spare production silicon detector modules for the current D0 silicon detector. The lifetime expectations due to radiation damage effects of the existing silicon detector are reviewed. A new upgrade project was started with the goal of a complete replacement of the existing silicon detector. In that context, several investigations on the radiation hardness of new prototype silicon microstrip detectors were carried out. The irradiation on different detector types was performed with 10 MeV protons up to fluences of 10 14 p/cm 2 at the J.R. Mcdonald Laboratory at Kansas State University. The flux calibration was carefully checked using different normalization techniques. As a result, we observe roughly 40-50% less radiation damage in silicon for 10 MeV p exposure than it is expected by the predicted NIEL scaling

Multi-scale approach to radiation damage induced by ion beams: complex DNA damage and effects of thermal spikes

International Nuclear Information System (INIS)

Surdutovich, E.; Yakubovich, A.V.; Solov'yov, A.V.; Surdutovich, E.; Yakubovich, A.V.; Solov'yov, A.V.

2010-01-01

We present the latest advances of the multi-scale approach to radiation damage caused by irradiation of a tissue with energetic ions and report the calculations of complex DNA damage and the effects of thermal spikes on biomolecules. The multi-scale approach aims to quantify the most important physical, chemical, and biological phenomena taking place during and following irradiation with ions and provide a better means for clinically-necessary calculations with adequate accuracy. We suggest a way of quantifying the complex clustered damage, one of the most important features of the radiation damage caused by ions. This quantification allows the studying of how the clusterization of DNA lesions affects the lethality of damage. We discuss the first results of molecular dynamics simulations of ubiquitin in the environment of thermal spikes, predicted to occur in tissue for a short time after an ion's passage in the vicinity of the ions' tracks. (authors)

Relaxation of Si-SiO2 interfacial stress in bipolar screen oxides due to ionizing radiation

International Nuclear Information System (INIS)

Witczak, S.C.; Galloway, K.F.; Schrimpf, R.D.; Suehle, J.S.

1995-01-01

Current gain degradation due to ionizing radiation in complementary single-crystalline emitter bipolar transistors was found to grow progressively worse upon subjecting the transistors to repeated cycles of radiation exposure and high-temperature anneal. The increase in radiation sensitivity is independent of the emitter polarity or geometry and is most dramatic between the first and second radiation and anneal cycles. In parallel with the current gain measurements, samples from a monitor wafer simulating the screen oxide region above the extrinsic base in the npn transistors were measured for mechanical stress while undergoing similar cycles of irradiation and anneal. The oxide on the monitor wafer consisted of a 45 nm thermal layer and a 640 nm deposited layer. The results indicate that ionizing radiation helped relieve compressive stress at the Si surface. The magnitude of the stress change due to radiation is smaller than the stress induced by the emitter contact metallization followed by a post-metallization anneal. Correlation of radiation sensitivity in the bipolar transistors and mechanical stress in the monitor wafer suggests that mechanical stress may be influential in determining the radiation hardness of bipolar transistors and lends validation to previously reported observations that Si-SiO 2 interfaces are increasingly more susceptible to radiation damage with decreasing Si compressive stress. Possible mechanisms for the observed changes in stress and their effect on the radiation sensitivity of the bipolar transistors are discussed

Parameterisation of radiation effects on CVD diamond for proton irradiation

International Nuclear Information System (INIS)

Hartjes, F.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.

1999-01-01

The paper reviews measurements of the radiation hardness of CVD diamond for 24 GeV/c proton irradiation at fluences up to 5 * 10 15 protons/cm 2 . The results not only show radiation damage but also an annealing effect that is dominant at levels around 10 15 protons/cm 2 . A model describing both effects is introduced, enabling a prediction of the distribution curve of the charge signal for other levels

PUMN: a radiation damage simulation computer program for the WINERY system

International Nuclear Information System (INIS)

Kuspa, J.P.

1976-01-01

The WINERY Radiation Damage Computer Simulation System will attempt to solve the entire radiation damage problem from the incident radiation to the property changes which occur in the material, using a set of interrelated computer programs. Computer simulation may be indispensable to the study of the radiation damage to materials in breeder and fusion reactors. WINERY is introduced with this work, and one portion of the system, the PUMN program, is developed and used to obtain important radiation damage results with Fe 3 Al crystal. PUMN is a program which simulates the response of the atoms in a crystal to a knock-on atom. It yields the damage configuration of the crystal by considering the dynamic interaction of all the atoms of the computational cell, up to 1000 atoms. The trajectories of the atoms are calculated using the Nordsieck Method, which has a prediction step based upon Taylor series expansions of the position and its first five time derivatives, and has a correction sequence which uses coefficients which have been optimized for efficiency and accuracy. Other features, such as restart files, automatic time step control, and crystal extension, make PUMN a versatile program which can simulate cases of relatively high knock-on energy, at least up to 500 eV. The PUMN program provides the WINERY system with results for the number of displacements, N/sub d/, due to knock-on atoms with various energies. This study dealt exclusively with Fe 3 Al. The values of N/sub d/ for Fe 3 Al were obtained at two different energies, 100 eV and 500 eV, for a variety of initial directions

Assessment of DNA damage in radiation workers by using single cell gel electrophoresis

International Nuclear Information System (INIS)

Jia Lili; Zhang Tao; Yang Yonghua; Wang Yan; Du Liqing; Cao Jia; Wang Hong; Liu Qiang; Fan Feiyue

2010-01-01

Objective: To assess the DNA damage of radiation workers in different grade hospitals, and to explore the correlation between the types of work or work time and the levels of DNA damage. Methods: DNA single strand break were detected by using alkaline single cell gel electrophoresis (SCGE), and the comet was analyzed with CASP (Comet Assay Software Project). TDNA%, TL, TM and OTM were calculated. Results: The parameters of SCGE in the radiation group were higher than those of control group (F=3.93, P<0.01). The significant difference was found not only among the different types of work or different work time, but also among the different grade hospitals (F=1.83, 1.91, P<0.05). Conclusions: Various levels of DNA damage could be detected in the radiation workers of the two hospitals. DNA damage of radiation workers is less serious in the higher-grade hospital than the lower grade one. Different types of work or work time might affect the DNA damage level. (authors)

Neutron flux and annealing effects on irradiation hardening of RPV materials

Science.gov (United States)

Chaouadi, R.; Gérard, R.

2011-11-01

This paper aims to examine an eventual effect of neutron flux, sometimes referred to as dose rate effect, on irradiation hardening of a typical A533B reactor pressure vessel steel. Tensile tests on both low flux (reactor surveillance data) and high flux (BR2 reactor) were performed in a large fluence range. The obtained results indicate two features. First, the surveillance data exhibit a constant (˜90 MPa) higher yield strength than the high flux data. However, this difference cannot be explained from a flux effect but most probably from differences in the initial tensile properties. The hardening kinetic of both low and high flux is the same. Annealing at low temperature, 345 °C/40 h, to eventually reveal unstable matrix damage did not affect both BR2 and surveillance specimens. This is confirmed by other annealing experimental data including both tensile and hardness measurements and tensile data on A508 forging and weld. It is suggested that the absence of flux effect on the tensile properties while different radiation-induced microstructures can be attributed to thermal ageing effects.

Annealing of Al implanted 4H silicon carbide

International Nuclear Information System (INIS)

Hallen, A; Suchodolskis, A; Oesterman, J; Abtin, L; Linnarsson, M

2006-01-01

Al ions were implanted with multiple energies up to 250 keV at elevated temperatures in n-type 4H SiC epitaxial layers to reach a surface concentration of 1x10 20 cm -3 . These samples were then annealed at temperatures between 1500 and 1950 deg. C. A similar 4H SiC epitaxial sample was implanted by MeV Al ions to lower doses and annealed only at 200 and 400 deg. C. After annealing, cross-sections of the samples were characterized by scanning spreading resistance microscopy (SSRM). The results show that the resistivity of high-dose Al implanted samples has not reached a saturated value, even after annealing at the highest temperature. For the MeV Al implanted sample, the activation of Al has not yet started, but a substantial annealing of the implantation induced damage can be seen from the SSRM depth profiles

Annealing of silicon epitaxial n+-p-structures irradiated with fast electrons

International Nuclear Information System (INIS)

Korshunov, F.P.; Turin, P.M.; Gurinovich, V.A.; Zhdanovich, N.E.

2010-01-01

Static (forward voltage drop and barrier capacitance) and dynamic (minority charge carriers lifetime in p-base) parameters changes of n + -p-structures irradiated with electrons (6 MeV) have been investigated. It is established that the forward voltage drop and the barrier capacitance of n + -p-junction recover during annealing at about 623 K, but the minority charge carriers lifetime recovery occurs at annealing temperatures above 773 K. The recovery of a forward voltage drop and barrier capacitance is related with annealing of radiation complexes of divacancy-oxygen (V 2 O) and boron-carbon (B i C s ). The recovery of minority charge carriers lifetime in structures is related mainly with annealing of radiation complex of carbonoxygen (C i O i ). (authors)

Involvement of membrane lipids in radiation damage to potassium-ion permeability of Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Suzuki, S [Tokyo Univ. (Japan). Inst. for Medical Science; Akamatsu, Y

1978-02-01

Radiation damage to K/sup +/ permeability of an unsaturated fatty acid auxotroph of E.coli grown with oleate or linolenate was investigated at different temperatures. A remarkable effect of radiation was observed at 0/sup 0/C with cells that had been grown in linolenate at 42/sup 0/C. This indicates that, besides protein, membrane lipids at least are involved in the radiation damage. The damage also seems to be affected by the fluidity of membrane lipids.

Multiscale approach to the physics of radiation damage with ions

International Nuclear Information System (INIS)

Surdutovich, E.; Solov'yov, A.

2014-01-01

The multiscale approach to the assessment of bio-damage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches. The processes of ion propagation in the medium concurrent with ionization and excitation of molecules, transport of secondary products, dynamics of the medium, and biological damage take place on a number of different temporal, spatial and energy scales. The multiscale approach, a physical phenomenon-based analysis of the scenario that leads to radiation damage, has been designed to consider all relevant effects on a variety of scales and develop an approach to the quantitative assessment of biological damage as a result of irradiation with ions. Presently, physical and chemical effects are included in the scenario while the biological effects such as DNA repair are only mentioned. This paper explains the scenario of radiation damage with ions, overviews its major parts, and applies the multiscale approach to different experimental conditions. On the basis of this experience, the recipe for application of the multiscale approach is formulated. The recipe leads to the calculation of relative biological effectiveness. (authors)

Advances in SSTR techniques for dosimetry and radiation damage measurements

International Nuclear Information System (INIS)

Gold, R.; Roberts, J.H.; Ruddy, F.H.

1979-01-01

Solid state track recorders (SSTR) have been applied in the diverse nuclear reactor research. Two recent advances are described which possess outstanding relevance for reactor research, namely the evolvement of SSTR radiation damage monitors and the development of CR-39, a new plastic SSTR of extremely high sensitivity. Results from high fluence irradiations of natural quartz crystal SSTR are used to illustrate the concept of the SSTR radiation damage monitor. Response characteristics of CR-39 are presented with emphasis on the remarkable proton sensitivity of this new SSTR

Delayed repair of radiation induced clustered DNA damage: Friend or foe?

Science.gov (United States)

Eccles, Laura J.; O’Neill, Peter; Lomax, Martine E.

2011-01-01

A signature of ionizing radiation exposure is the induction of DNA clustered damaged sites, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. Clustered damage is made up of double strand breaks (DSB) with associated base lesions or abasic (AP) sites, and non-DSB clusters comprised of base lesions, AP sites and single strand breaks. This review will concentrate on the experimental findings of the processing of non-DSB clustered damaged sites. It has been shown that non-DSB clustered damaged sites compromise the base excision repair pathway leading to the lifetime extension of the lesions within the cluster, compared to isolated lesions, thus the likelihood that the lesions persist to replication and induce mutation is increased. In addition certain non-DSB clustered damaged sites are processed within the cell to form additional DSB. The use of E. coli to demonstrate that clustering of DNA lesions is the major cause of the detrimental consequences of ionizing radiation is also discussed. The delayed repair of non-DSB clustered damaged sites in humans can be seen as a “friend”, leading to cell killing in tumour cells or as a “foe”, resulting in the formation of mutations and genetic instability in normal tissue. PMID:21130102

Measurements and TCAD Simulations of Bulk and Surface Radiation Damage Effects

CERN Document Server

F. Moscatelli; G. M. Bilei; A. Morozzi; G.-F. Dalla Betta; R. Mendicino; M. Boscardin; N. Zorzi; L. Servoli; P. Maccagnani

2016-01-01

In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1÷2×1016 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures.

Radiation damage relative to transmission electron microscopy of biological specimens at low temperature: a review

International Nuclear Information System (INIS)

Glaeser, R.M.; Taylor, K.A.

1978-01-01

When biological specimens are irradiated by the electron beam in the electron microscope, the specimen structure is damaged as a result of molecular excitation, ionization, and subsequent chemical reactions. The radiation damage that occurs in the normal process of electron microscopy is known to present severe limitations for imaging high resolution detail in biological specimens. The question of radiation damage at low temperatures has therefore been investigated with the view in mind of reducing somewhat the rate at which damage occurs. The radiation damage protection found for small molecule (anhydrous) organic compounds is generally rather limited or even non-existent. However, large molecule, hydrated materials show as much as a 10-fold reduction at low temperature in the rate at which radiation damage occurs, relative to the damage rate at room temperature. In the case of hydrated specimens, therefore, low temperature electron microscopy offers an important advantage as part of the overall effort required in obtaining high resolution images of complex biological structures. (author)

On radiation damage to normal tissues and its treatment. Pt. 2

International Nuclear Information System (INIS)

Michalowski, A.S.

1994-01-01

In addition to transiently inhibiting cell cycle progression and sterilizing those cells capable of proliferation, irradiation disturbs the homeostasis effected by endogenous mediators of intercellular communication (humoral component of tissue response to radiation). Changes in the mediator levels may modulate radiation effects either by a assisting a return to normality (e.g., through a rise in H-type cell lineage-specific growth factors) or by aggravating the damage. The latter mode is illustrated with reports on changes in eicosanoid levels after irradiation and on results of empirical treatment of radiation injuries with anti-inflammatory drugs. Prodromal, acute and chronic effects of radiation are accompanied by excessive production of eicosanoids (prostaglandins, prostacyclin, thromboxanes and leukotrienes). These endogenous mediators of inflammatory reactions may be responsible for the vasodilatation, vasoconstriction, increased microvascular permeability, thrombosis and chemotaxis observed after radiation exposure. Glucocorticoids inhibit eicosanoid synthesis primarily by interfering with phospholipase A 2 whilst non-steroidal anti-inflammatory drugs prevent prostaglandin/thromboxane synthesis by inhibiting cycloxygenase. When administered after irradiation on empirical grounds, drugs belonging to both groups tend to attenuate a range of prodomal, acute and chronic effects of radiation in man and animals. Taken together, these two sets of observations are highly suggestive of a contribution of humoral factors to the adverse responses of normal tissues and organs to radiation. A full account of radiation damage should therefore consist of complementary descriptions of cellular and humoral events. Further studies on anti-inflammatory drug treatment of radiation damage to normal organs are justified and desirable. (orig.)

Prediction of radiation-related small-bowel damage

International Nuclear Information System (INIS)

Potish, R.A.

1980-01-01

In order to predict which patients have a high risk for radiation-related small-bowel damage, the concept of the dose-response curve was applied to the predisposing factors (number of previous laparotomies, extent of surgery, thin physique, hypertension, age, cancer stage, number of treatment days, fractionation, and weight change during radiotherapy) present in 92 patients receiving identical radiation doses and volumes This analysis allows an estimate of the probability of complication to be assigned to individual patients. The utility and limitations of the dose-response concept are discussed

Radiation damage in natural materials: implications for radioactive waste forms

International Nuclear Information System (INIS)

Ewing, R.C.

1981-01-01

The long-term effect of radiation damage on waste forms, either crystalline or glass, is a factor in the evaluation of the integrity of waste disposal mediums. Natural analogs, such as metamict minerals, provide one approach for the evaluaton of radiation damage effects that might be observed in crystalline waste forms, such as supercalcine or synroc. Metamict minerals are a special class of amorphous materials which were initially crystalline. Although the mechanism for the loss of crystallinity in these minerals (mostly actinide-containing oxides and silicates) is not clearly understood, damage caused by alpha particles and recoil nuclei is critical to the metamictization process. The study of metamict minerals allows the evaluation of long-term radiation damage effects, particularly changes in physical and chemical properties such as microfracturing, hydrothermal alteration, and solubility. In addition, structures susceptible to metamictization share some common properties: (1) complex compositions; (2) some degree of covalent bonding, instead of being ionic close-packed MO/sub x/ structures; and (3) channels or interstitial voids which may accommodate displaced atoms or absorbed water. On the basis of these empirical criteria, minerals such as pollucite, sodalite, nepheline and leucite warrant careful scrutiny as potential waste form phases. Phases with the monazite or fluorite structures are excellent candidates

Specific chemical and structural damage to proteins produced by synchrotron radiation.

Science.gov (United States)

Weik, M; Ravelli, R B; Kryger, G; McSweeney, S; Raves, M L; Harel, M; Gros, P; Silman, I; Kroon, J; Sussman, J L

2000-01-18

Radiation damage is an inherent problem in x-ray crystallography. It usually is presumed to be nonspecific and manifested as a gradual decay in the overall quality of data obtained for a given crystal as data collection proceeds. Based on third-generation synchrotron x-ray data, collected at cryogenic temperatures, we show for the enzymes Torpedo californica acetylcholinesterase and hen egg white lysozyme that synchrotron radiation also can cause highly specific damage. Disulfide bridges break, and carboxyl groups of acidic residues lose their definition. Highly exposed carboxyls, and those in the active site of both enzymes, appear particularly susceptible. The catalytic triad residue, His-440, in acetylcholinesterase, also appears to be much more sensitive to radiation damage than other histidine residues. Our findings have direct practical implications for routine x-ray data collection at high-energy synchrotron sources. Furthermore, they provide a direct approach for studying the radiation chemistry of proteins and nucleic acids at a detailed, structural level and also may yield information concerning putative "weak links" in a given biological macromolecule, which may be of structural and functional significance.

Computer simulation of radiation damage in HTGR elements and structural materials

International Nuclear Information System (INIS)

Gann, V.V.; Gurin, V.A.; Konotop, Yu.F.; Shilyaev, B.A.; Yamnitskij, V.A.

1980-01-01

The problem of mathematical simulation of radiation damages in material and items of HTGR is considered. A system-program complex IMITATOR, intended for imitation of neutron damages by means of charged particle beams, is used. Account of material composite structure and certain geometry of items permits to calculate fields of primary radiation damages and introductions of reaction products in composite fuel elements, microfuel elements, their shells, composite absorbing elements on the base of boron carbide, structural steels and alloys. A good correspondence of calculation and experimental burn-out of absorbing elements is obtained, application of absorbing element as medium for imitation experiments is grounded [ru

Umbelliferone suppresses radiation induced DNA damage and apoptosis in hematopoietic cells of mice

International Nuclear Information System (INIS)

Jayakumar, S.; Bhilwade, H.N.; Chaubey, R.C.

2012-01-01

Radiotherapy is one of the major modes of treatment for different types of cancers. But the success of radiotherapy is limited by injury to the normal cells. Protection of the normal cells from radiation damage by radioprotectors can increase therapeutic efficiency. These radioprotectors can also be used during nuclear emergency situations. Umbelliferone (UMB) is a wide spread natural product of the coumarin family. It occurs in many plants from the Apiaceae family. In the present study radioprotective effect of UMB was investigated in vitro and in vivo. Anti genotoxic effect of Umbelliferone was tested by treating the splenic lymphocytes with various doses of UMB (6.5 μM - 50 μM) prior to radiation (6Gy) exposure. After the radiation exposure, extent of DNA damage was assessed by comet assay at 5 mm and two hours after radiation exposure. At both the time points, it was observed that the pretreatment of UMB reduced the radiation induced DNA damage to a significant extent in comparison to radiation control. UMB pretreatment also significantly reduced the radiation induced apoptosis enumerated by propidium iodide staining assay. Results of clonogenic survival assay using intestinal cell line showed that pretreatment with UMB significantly protected against radiation induced loss of colony forming units. To assess the anti genotoxic role of umbelliferone in vivo two different doses of UMB (20 mg/Kg and 40 mg/Kg of body weight) were injected into Swiss mice or with vehicle and exposed to radiation. Thirty minutes after the radiation comet assay was performed in peripheral leukocytes. Frequency of micro nucleated erythrocytes was scored in bone marrow cells. It was observed that UMB alone did not cause any significant increase in DNA damage in comparison to control. Animals which are exposed to radiation alone showed significant increase in DNA damage and micronuclei frequency. But animals treated with UMB prior to the radiation exposure showed significant decrease

The use of the SRIM code for calculation of radiation damage induced by neutrons

Science.gov (United States)

Mohammadi, A.; Hamidi, S.; Asadabad, Mohsen Asadi

2017-12-01

Materials subjected to neutron irradiation will being evolve to structural changes by the displacement cascades initiated by nuclear reaction. This study discusses a methodology to compute primary knock-on atoms or PKAs information that lead to radiation damage. A program AMTRACK has been developed for assessing of the PKAs information. This software determines the specifications of recoil atoms (using PTRAC card of MCNPX code) and also the kinematics of interactions. The deterministic method was used for verification of the results of (MCNPX+AMTRACK). The SRIM (formely TRIM) code is capable to compute neutron radiation damage. The PKAs information was extracted by AMTRACK program, which can be used as an input of SRIM codes for systematic analysis of primary radiation damage. Then the Bushehr Nuclear Power Plant (BNPP) radiation damage on reactor pressure vessel is calculated.

Improved luminescence properties of nanocrystalline silicon based electroluminescent device by annealing

International Nuclear Information System (INIS)

Sato, Keisuke; Hirakuri, Kenji

2006-01-01

We report an annealing effect on electrical and luminescence properties of a red electroluminescent device consisting of nanocrystalline silicon (nc-Si). The red luminescence was generated by flowing the forward current into the device at a low threshold direct current (DC) forward voltage with a rise of annealing temperature up to 500 deg. C. Moreover, the luminescence of the device annealed at 500 deg. C was more intense than that of the device annealed at 200 deg. C or less under the same forward current density, because of the injection of a large quantity of carriers to the radiative recombination centers at the nc-Si surface vicinity. These were attained by a low resistivity of indium tin oxide (ITO) electrode and good contact at the ITO electrode/luminous layer interface region by the annealing treatment. The above results indicated that the annealing treatment of the device is effective for the realization of high luminance due to the improvement in the injection efficiency of carriers to the radiative recombination centers

Gamma radiation damage in pixelated detector based on carbon nanotubes

International Nuclear Information System (INIS)

Leyva, A.; Pinnera, I.; Leyva, D.; Abreu, Y.; Cruz, C. M.

2013-01-01

The aim of this paper is to evaluate the possible gamma radiation damage in high pixelated based on multi-walled carbon nanotubes detectors, grown on two different substrata, when it is operating in aggressive radiational environments. The radiation damage in displacements per atom (dpa) terms were calculated using the MCCM algorithm, which takes into account the McKinley-Feshbach approach with the Kinchin-Pease approximation for the damage function. Was observed that with increasing of the gamma energy the displacement total number grows monotonically reaching values of 0.39 displacements for a 10 MeV incident photon. The profiles of point defects distributions inside the carbon nanotube pixel linearly rise with depth, increasing its slope with photon energy. In the 0.1 MeV - 10 MeV studied energy interval the electron contribution to the total displacement number become higher than the positron ones, reaching this last one a maximum value of 12% for the 10 MeV incident photons. Differences between the calculation results for the two used different substrata were not observed. (Author)

Dependence of defect introduction on temperature and resistivity and some long-term annealing effects

Science.gov (United States)

Brucker, G. J.

1971-01-01

The effort reported here represents data of lithium properties in bulk-silicon samples before and after irradiation for analytical information required to characterize the interactions of lithium with radiation-induced defects in silicon. A model of the damage and recovery mechanisms in irradiated-lithium-containing solar cells is developed based on making measurements of the Hall coefficient and resistivity of samples irradiated by 1-MeV electrons. Experiments on bulk samples included Hall coefficient and resistivity measurements taken as a function of: (1) bombardment temperature, (2) resistivity, (3) fluence, (4) oxygen concentration, and (5) annealing time at temperatures from 300 to 373 K.

PREFACE: Radiation Damage in Biomolecular Systems (RADAM07)

Science.gov (United States)

McGuigan, Kevin G.

2008-03-01

The annual meeting of the COST P9 Action `Radiation damage in biomolecular systems' took place from 19-22 June 2007 in the Royal College of Surgeons in Ireland, in Dublin. The conference was structured into 5 Working Group sessions: Electrons and biomolecular interactions Ions and biomolecular interactions Radiation in physiological environments Theoretical developments for radiation damage Track structure in cells Each of the five working groups presented two sessions of invited talks. Professor Ron Chesser of Texas Tech University, USA gave a riveting plenary talk on `Mechanisms of Adaptive Radiation Responses in Mammals at Chernobyl' and the implications his work has on the Linear-No Threshold model of radiation damage. In addition, this was the first RADAM meeting to take place after the Alexander Litvenenko affair and we were fortunate to have one of the leading scientists involved in the European response Professor Herwig Paretzke of GSF-Institut für Strahlenschutz, Neuherberg, Germany, available to speak. The remaining contributions were presented in the poster session. A total of 72 scientific contributions (32 oral, 40 poster), presented by 97 participants from 22 different countries, gave an overview on the current progress in the 5 different subfields. A 1-day pre-conference `Early Researcher Tutorial Workshop' on the same topic kicked off on 19 June attended by more than 40 postgrads, postdocs and senior researchers. Twenty papers, based on these reports, are included in this volume of Journal of Physics: Conference Series. All the contributions in this volume were fully refereed, and they represent a sample of the courses, invited talks and contributed talks presented during RADAM07. The interdisciplinary RADAM07 conference brought together researchers from a variety of different fields with a common interest in biomolecular radiation damage. This is reflected by the disparate backgrounds of the authors of the papers presented in these proceedings

Mechanisms for radiation damage in DNA. Final report, June 1, 1986--August 31, 1996

International Nuclear Information System (INIS)

Sevilla, M.D.

1996-08-01

Over the last 10 years significant advances have been made impacting the understanding of radiation damage to DNA. The principal objective of this work was the elucidation of the fundamental mechanisms of radiation damage to DNA through the direct and indirect effects. Recently the work concentrated on the direct effect of radiation damage on DNA. The objective was to elucidate the ultimate radiation chemical damage to DNA arising from the direct effect. In this effort the focus was on the application of three techniques. ESR spectroscopic measurement of initial radicals formed in DNA and its hydration layer at low temperatures. Ab initio molecular orbital calculations were employed to give highly accurate theoretical predictions of early events such as electron and hole localization sites which serve to test and to clarify the experimental observations. HPLC and GC-mass spectroscopic assays of DNA base products formation provide the ultimate chemical outcome of the initial radiation events. The bridge between the early ion radical species and the non-radical products is made in ESR studies which follow the chemistry of the early species as they react with water and or other DNA bases. The use of these techniques has resulted in a new and fundamental understanding of the radiation damage to DNA on a molecular scale. From this work, a working model for DNA damage from the initial ionization event to the eventual formation of molecular base damage products and strand breaks has been formulated. Results over the past several years which have led to the formulation of this model are described

Introduction to neutron metrology for reactor radiation damage

International Nuclear Information System (INIS)

Alberman, A.; Genthon, J.P.; Wright, S.B.; Zijp, W.L.

1977-01-01

This document, prepared by members of the Irradiation Damage Subgroup of the Euratom Working Group on Reactor Dosimetry (EWGRD) describes the background of the procedures for determining irradiation parameters which are of interest in radiation damage experiments. The first two chapters outline the concept of damage functions and damge models. The next two chapters give information on methods to determine neutron fluences and neutron spectra. The fifth chapter gives a review of correlation data available for graphite and steels. The last chapter gives guidance how to report the relevant irradiation parameters. Attention is given to the role of the neutron spectrum in deriving values for damage fluence, energy transferred to the lattice, and number of displacements. A suggested list to report data relevant to the irradiation, the instrumentation and the testing of material is included

Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

Energy Technology Data Exchange (ETDEWEB)

Marathe, D.L.; Pandey, B.N.; Mishra, K.P [Bhabha Atomic Research Centre, Mumbai (India)

2000-05-01

Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that {alpha}-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

International Nuclear Information System (INIS)

Marathe, D.L.; Pandey, B.N.; Mishra, K.P

2000-01-01

Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that α-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

Particle interaction and displacement damage in silicon devices operated in radiation environments

International Nuclear Information System (INIS)

Leroy, Claude; Rancoita, Pier-Giorgio

2007-01-01

Silicon is used in radiation detectors and electronic devices. Nowadays, these devices achieving submicron technology are parts of integrated circuits of large to very large scale integration (VLSI). Silicon and silicon-based devices are commonly operated in many fields including particle physics experiments, nuclear medicine and space. Some of these fields present adverse radiation environments that may affect the operation of the devices. The particle energy deposition mechanisms by ionization and non-ionization processes are reviewed as well as the radiation-induced damage and its effect on device parameters evolution, depending on particle type, energy and fluence. The temporary or permanent damage inflicted by a single particle (single event effect) to electronic devices or integrated circuits is treated separately from the total ionizing dose (TID) effect for which the accumulated fluence causes degradation and from the displacement damage induced by the non-ionizing energy-loss (NIEL) deposition. Understanding of radiation effects on silicon devices has an impact on their design and allows the prediction of a specific device behaviour when exposed to a radiation field of interest

High pressure annealing of Europium implanted GaN

KAUST Repository

Lorenz, K.; Miranda, S. M. C.; Alves, E.; Roqan, Iman S.; O'Donnell, K. P.; Bokowski, M.

2012-01-01

GaN epilayers were implanted with Eu to fluences of 1×10^13 Eu/cm2 and 1×10^15 Eu/cm2. Post-implant thermal annealing was performed in ultra-high nitrogen pressures at temperatures up to 1450 ºC. For the lower fluence effective structural recovery of the crystal was observed for annealing at 1000 ºC while optical activation could be further improved at higher annealing temperatures. The higher fluence samples also reveal good optical activation; however, some residual implantation damage remains even for annealing at 1450 ºC which leads to a reduced incorporation of Eu on substitutional sites, a broadening of the Eu luminescence lines and to a strongly reduced fraction of optically active Eu ions. Possibilities for further optimization of implantation and annealing conditions are discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

High pressure annealing of Europium implanted GaN

KAUST Repository

Lorenz, K.

2012-02-09

GaN epilayers were implanted with Eu to fluences of 1×10^13 Eu/cm2 and 1×10^15 Eu/cm2. Post-implant thermal annealing was performed in ultra-high nitrogen pressures at temperatures up to 1450 ºC. For the lower fluence effective structural recovery of the crystal was observed for annealing at 1000 ºC while optical activation could be further improved at higher annealing temperatures. The higher fluence samples also reveal good optical activation; however, some residual implantation damage remains even for annealing at 1450 ºC which leads to a reduced incorporation of Eu on substitutional sites, a broadening of the Eu luminescence lines and to a strongly reduced fraction of optically active Eu ions. Possibilities for further optimization of implantation and annealing conditions are discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

An annealing study of charge collection efficiency on Float-Zone p-on-n ministrip sensors irradiated with 24 GeV/c protons and 20 MeV neutrons

International Nuclear Information System (INIS)

Pacifico, N.; Dolenc-Kittelmann, I.; Gabrysch, M.; Moll, M.; Lucas, C.

2015-01-01

Float-Zone n-bulk p-readout silicon sensors are currently operated in the tracking layers of many High Energy Physics experiments, where they are exposed to moderate to high fluences of hadrons. Though n-readout sensors, either with p or n bulk, are available and are offering an improved radiation hardness, p-on-n sensors are still widely used and are e.g. installed in the present ATLAS and CMS experiments at CERN. Their radiation hardness and long-term performance are therefore of high interest to the detector community. We present here a study performed on these sensors after irradiation with 24 GeV/c protons and 20 MeV neutrons to fluences ranging from 1⋅10 14 to 1⋅10 15 n eq /cm 2 . The sensors were then investigated for charge collection efficiency after different isothermal annealing steps in order to understand the performance evolution of the sensor with annealing time. Additional measurements were performed for the highest neutron fluence by means of the Edge-TCT technique, to assess the electric field configuration within the sensor. The irradiation and the annealing scenarios were chosen to represent the radiation damage scenario over the expected lifetime of the LHC detectors (and even further) and to assess the effect of unplanned annealing due to potentially longer warm shutdowns or cooling problems

Parameterisation of radiation effects on CVD diamond for proton irradiation

Energy Technology Data Exchange (ETDEWEB)

Hartjes, F.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M

1999-08-01

The paper reviews measurements of the radiation hardness of CVD diamond for 24 GeV/c proton irradiation at fluences up to 5{sup *}10{sup 15} protons/cm{sup 2}. The results not only show radiation damage but also an annealing effect that is dominant at levels around 10{sup 15} protons/cm{sup 2}. A model describing both effects is introduced, enabling a prediction of the distribution curve of the charge signal for other levels.

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

Science.gov (United States)

Gill, Sarvajeet S.; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315–400 nm; UV-B, 280–315 nm; and UV-C, important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH•) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context. PMID:25729769

Melting phenomenon and laser annealing in semiconductors

International Nuclear Information System (INIS)

Narayan, J.

1981-03-01

The work on annealing of displacement damage, dissolution of boron precipitates, and the broadening of dopant profiles in semiconductors after treating with ruby and dye laser pulses is reviewed in order to provide convincing evidence for the melting phenomenon and illustrate the mechanism associated with laser annealing. The nature of the solid-liquid interface and the interface instability during rapid solidification is considered in detail. It is shown that solute concentrations after pulsed laser annealing can far exceed retrograde maxima values. However, there is a critical solute concentration above which a planar solid-liquid interface becomes unstable and breaks into a cellular structure. The solute concentrations and cell sizes associated with this instability are calculated using a perturbation theory, and compared with experimental results

Protecting the radiation-damaged skin from friction: a mini review

International Nuclear Information System (INIS)

Herst, Patries M

2014-01-01

Radiation-induced skin reactions are an unavoidable side effect of external beam radiation therapy, particularly in areas prone to friction and excess moisture such as the axilla, head and neck region, perineum and skin folds. Clinical studies investigating interventions for preventing or managing these reactions have largely focussed on formulations with moisturising, anti-inflammatory, anti-microbial and wound healing properties. However, none of these interventions has emerged as a consistent candidate for best practice. Much less emphasis has been placed on evaluating ways to protect the radiation-damaged skin from friction and excess moisture. This mini review analyses the clinical evidence for barrier products that form a protective layer by adhering very closely to the skin folds and do not cause further trauma to the radiation-damaged skin upon removal. A database search identified only two types of barrier products that fitted these criteria and these were tested in two case series and six controlled clinical trials. Friction protection was most effective when the interventions were used from the start of treatment and continued for several weeks after completion of treatment. Soft silicone dressings (Mepilex Lite and Mepitel Film) and Cavilon No Sting Barrier Film, but not Cavilon Moisturizing Barrier Cream, decreased skin reaction severity, most likely due to differences in formulation and skin build-up properties. It seems that prophylactic use of friction protection of areas at risk could be a worthwhile addition to routine care of radiation-damaged skin

Modification of radiation damage in CHO cells by hyperthermia at 40 and 450C

International Nuclear Information System (INIS)

Henle, K.J.; Leeper, D.B.

1977-01-01

Low hyperthermia at 40 0 C either before or after X irradiation did not alter the slope of the radiation dose-cell survival curve but reduced the D/sub q/ from 145 to 41 or to 0 rad for a pre- or postirradiation incubation period of 2 hr at 40 0 C, respectively. In contrast, hyperthermia at 45 0 C increased the slope of the radiation survival curve by a factor of 1.7 for a radiation pretreatment of 10 min at 45 0 C, but only by 1.3 for the same treatment immediately after irradiation. The corresponding D/sub q/'s were 262 and 138 rad, respectively. A combination of 45 and 40 0 C hyperthermia (10 min at 45 0 C + 2 hr at 40 0 C + X) resulted in a superposition of the individual effects of 45 or 40 0 C hyperthermia on the radiation survival curve. In addition, the radiation survival curve was shifted downward by a factor of three due to the potentiation of 45 0 C hyperthermia damage by postincubation at 40 0 C. Repair of sublethal radiation damage was completely suppressed during incubation at 40 following hyperthermia at 45 0 C. However, when cells were returned to 37 0 C, even after 6 hr at 40 following 45 0 C hyperthermia, the capacity to accumulate and repair sublethal radiation damage was immediately restored. These findings imply that the hyperthermia damage from low or high temperatures interacts differentially with radiation damage. Low hyperthermia at 40 0 C may affect principally the radiation repair system, whereas 45 0 C hyperthermia probably alters the radiation target more severely than the repair system

Radiobiology in clinical radiation therapy - Part III: Normal tissue damage

International Nuclear Information System (INIS)

Travis, Elizabeth L.

1996-01-01

Objective: This is the third part of a course designed for residents in radiation oncology preparing for their boards. This part of the course will focus on the mechanisms underlying damage in normal tissues. Although conventional wisdom long held that killing and depletion of a critical cell(s) in a tissue was responsible for the later expression of damage, histopathologic changes in normal tissue can now be explained and better understood in terms of the new molecular biology. The concept that depletion of a single cell type is responsible for the observed histopathologic changes in normal tissues has been replaced by the hypothesis that damage results from the interaction of many different cell systems, including epithelial, endothelial, macrophages and fibroblasts, via the production of specific autocrine, paracrine and endocrine growth factors. A portion of this course will discuss the clinical and experimental data on the production and interaction of those cytokines and cell systems considered to be critical to tissue damage. It had long been suggested that interindividual differences in radiation-induced normal tissue damage was genetically regulated, at least in part. Both clinical and experimental data supported this hypothesis but it is the recent advances in human and mouse molecular genetics which have provided the tools to dissect out the genetic component of normal tissue damage. These data will be presented and related to the potential to develop genetic markers to identify sensitive individuals. The impact on clinical outcome of the ability to identify prospectively sensitive patients will be discussed. Clinically it is well-accepted that the volume of tissue irradiated is a critical factor in determining tissue damage. A profusion of mathematical models for estimating dose-volume relationships in a number of organs have been published recently despite the fact that little data are available to support these models. This course will review the

Repair of radiation damage in mammalian cells: its relevance to environmental effects

International Nuclear Information System (INIS)

Han, A.; Elkind, M.M.

1979-01-01

Assessment of the potential biological hazards associated with energy production technologies involves the quantitation of risk on the basis of dose-effect dependencies, from which, it is hoped, some safety guidelines can be developed. Our current knowledge of the biological importance of damage/repair processes stems by and large from radiation studies which clearly demonstrate that cellular response to radiation depends upon the ability of cells to repair the damage. Apparently, the same is true for cellular response to different chemical agents. Drawing upon our experiences from radiation studies, we demonstrate the relevance of ongoing repair processes, as evident in the studies of radiation induced cell killing and neoplastic transformation, to the type of risk estimates that might be associated with the hazards from energy production technologies. The effect of repair on cell survival is considered. It is evident from our studies that in the region of small doses, repair of damage relative to cell lethality is of importance in estimating the magnitude of effect. Aside from the cytotoxic effects in terms of cell killing, one of the greatest concerns associated with energy production is the potential of a given technology, or its effluents, to produce cancer. It is therefore of importance to quantify the risk in this context of damage registration and possible effect of repair on damage expression. It has been generally established that exposure of normal cells in culture to a variety of known carcinogens results in neoplastic transformation. Our observations with C3H/10T1/2 cells in culture lend direct evidence for the hypothesis that reduced tumor incidences at low dose rates of radiation could be due to the repair of induced damage

The Addition of Manganese Porphyrins during Radiation Inhibits Prostate Cancer Growth and Simultaneously Protects Normal Prostate Tissue from Radiation Damage

Directory of Open Access Journals (Sweden)

Arpita Chatterjee

2018-01-01

Full Text Available Radiation therapy is commonly used for prostate cancer treatment; however, normal tissues can be damaged from the reactive oxygen species (ROS produced by radiation. In separate reports, we and others have shown that manganese porphyrins (MnPs, ROS scavengers, protect normal cells from radiation-induced damage but inhibit prostate cancer cell growth. However, there have been no studies demonstrating that MnPs protect normal tissues, while inhibiting tumor growth in the same model. LNCaP or PC3 cells were orthotopically implanted into athymic mice and treated with radiation (2 Gy, for 5 consecutive days in the presence or absence of MnPs. With radiation, MnPs enhanced overall life expectancy and significantly decreased the average tumor volume, as compared to the radiated alone group. MnPs enhanced lipid oxidation in tumor cells but reduced oxidative damage to normal prostate tissue adjacent to the prostate tumor in combination with radiation. Mechanistically, MnPs behave as pro-oxidants or antioxidants depending on the level of oxidative stress inside the treated cell. We found that MnPs act as pro-oxidants in prostate cancer cells, while in normal cells and tissues the MnPs act as antioxidants. For the first time, in the same in vivo model, this study reveals that MnPs enhance the tumoricidal effect of radiation and reduce oxidative damage to normal prostate tissue adjacent to the prostate tumor in the presence of radiation. This study suggests that MnPs are effective radio-protectors for radiation-mediated prostate cancer treatment.

Recovery and permanent radiation damage of plastic scintillators at different dose rates

International Nuclear Information System (INIS)

Bicken, B.; Holm, U.; Marckmann, T.; Wick, K.; Rhode, M.

1990-01-01

This paper reports on the radiation stability of plastic scintillators and wavelength shifters for the calorimeter of the ZEUS detector by irradiating them with protons, a 60 Co-source, and depleted uranium. Changes in light yield, absorption length and absorption coefficient have been measured for storage in inert and oxygen atmospheres during and after irradiation. Radiation doses up to 40 kGy with dose rates of 30 up to 2000 Gy/h have been applied. The polystyrene based scintillator SCSN-38 and the wavelength shifters Y-7 and K-27 in PMMA show an additional absorption but a recovery in air to a low permanent damage (at 10 kGy) which is proportional to the applied dose. Series investigations on samples of all production cycles of the ZEUS scintillators with high dose rates show only minor differences in radiation hardness. The recovery is described by a simple oxygen diffusion model for high and medium dose rates down to 30 Gy/h. During long term irradiations at low dose rates (<100 Gy/h) of 3 mm thick SCSN-38 in air the radiation damage recovers to a permanent damage which does not depend on the dose rate. On the other hand the radiation damage at very low dose rates (17 Gy/a) seems to be higher than expected for the accumulated dose

Role of charged particle irradiations in the study of radiation damage correlation

International Nuclear Information System (INIS)

Ishino, S.; Sekimura, N.

1990-01-01

Charged particle irradiations were originally expected to provide means to simulate the effect of neutron irradiations. However, it has been recognized that quantitative and sometimes even qualitative simulation of neutron radiation damage is difficult and the role of the charged particle irradiations has shifted to establishing fission-fusion correlation based on fundamental understanding of the radiation damage phenomena. The authors have been studying radiation effects in fusion materials using energetic ions from the latter standpoint. In this paper, the authors review recent results using a heavy-ion/electron microscope link facility together with sets of small heavy ion and light ion accelerators on cascade damage produced by energetic primary recoils and on the effect of helium on microstructural and microchemical evolution. Some of the other applications of the ion accelerators will also be mentioned. (orig.)

Can radiation damage to protein crystals be reduced using small-molecule compounds?

Energy Technology Data Exchange (ETDEWEB)

Kmetko, Jan [Kenyon College, Gambier, OH 43022 (United States); Warkentin, Matthew; Englich, Ulrich; Thorne, Robert E., E-mail: ret6@cornell.edu [Cornell University, Ithaca, NY 14853 (United States); Kenyon College, Gambier, OH 43022 (United States)

2011-10-01

Free-radical scavengers that are known to be effective protectors of proteins in solution are found to increase global radiation damage to protein crystals. Protective mechanisms may become deleterious in the protein-dense environment of a crystal. Recent studies have defined a data-collection protocol and a metric that provide a robust measure of global radiation damage to protein crystals. Using this protocol and metric, 19 small-molecule compounds (introduced either by cocrystallization or soaking) were evaluated for their ability to protect lysozyme crystals from radiation damage. The compounds were selected based upon their ability to interact with radiolytic products (e.g. hydrated electrons, hydrogen, hydroxyl and perhydroxyl radicals) and/or their efficacy in protecting biological molecules from radiation damage in dilute aqueous solutions. At room temperature, 12 compounds had no effect and six had a sensitizing effect on global damage. Only one compound, sodium nitrate, appeared to extend crystal lifetimes, but not in all proteins and only by a factor of two or less. No compound provided protection at T = 100 K. Scavengers are ineffective in protecting protein crystals from global damage because a large fraction of primary X-ray-induced excitations are generated in and/or directly attack the protein and because the ratio of scavenger molecules to protein molecules is too small to provide appreciable competitive protection. The same reactivity that makes some scavengers effective radioprotectors in protein solutions may explain their sensitizing effect in the protein-dense environment of a crystal. A more productive focus for future efforts may be to identify and eliminate sensitizing compounds from crystallization solutions.

Can radiation damage to protein crystals be reduced using small-molecule compounds?

International Nuclear Information System (INIS)

Kmetko, Jan; Warkentin, Matthew; Englich, Ulrich; Thorne, Robert E.

2011-01-01

Free-radical scavengers that are known to be effective protectors of proteins in solution are found to increase global radiation damage to protein crystals. Protective mechanisms may become deleterious in the protein-dense environment of a crystal. Recent studies have defined a data-collection protocol and a metric that provide a robust measure of global radiation damage to protein crystals. Using this protocol and metric, 19 small-molecule compounds (introduced either by cocrystallization or soaking) were evaluated for their ability to protect lysozyme crystals from radiation damage. The compounds were selected based upon their ability to interact with radiolytic products (e.g. hydrated electrons, hydrogen, hydroxyl and perhydroxyl radicals) and/or their efficacy in protecting biological molecules from radiation damage in dilute aqueous solutions. At room temperature, 12 compounds had no effect and six had a sensitizing effect on global damage. Only one compound, sodium nitrate, appeared to extend crystal lifetimes, but not in all proteins and only by a factor of two or less. No compound provided protection at T = 100 K. Scavengers are ineffective in protecting protein crystals from global damage because a large fraction of primary X-ray-induced excitations are generated in and/or directly attack the protein and because the ratio of scavenger molecules to protein molecules is too small to provide appreciable competitive protection. The same reactivity that makes some scavengers effective radioprotectors in protein solutions may explain their sensitizing effect in the protein-dense environment of a crystal. A more productive focus for future efforts may be to identify and eliminate sensitizing compounds from crystallization solutions

The yield, processing, and biological consequences of clustered DNA damage induced by ionizing radiation

International Nuclear Information System (INIS)

Shikazono, Naoya; Noguchi, Miho; Fujii, Kentaro; Urushibara, Ayumi; Yokoya, Akinari

2009-01-01

After living cells are exposed to ionizing radiation, a variety of chemical modifications of DNA are induced either directly by ionization of DNA or indirectly through interactions with water-derived radicals. The DNA lesions include single strand breaks (SSB), base lesions, sugar damage, and apurinic/apyrimidinic sites (AP sites). Clustered DNA damage, which is defined as two or more of such lesions within one to two helical turns of DNA induced by a single radiation track, is considered to be a unique feature of ionizing radiation. A double strand break (DSB) is a type of clustered DNA damage, in which single strand breaks are formed on opposite strands in close proximity. Formation and repair of DSBs have been studied in great detail over the years as they have been linked to important biological endpoints, such as cell death, loss of genetic material, chromosome aberration. Although non-DSB clustered DNA damage has received less attention, there is growing evidence of its biological significance. This review focuses on the current understanding of (1) the yield of non-DSB clustered damage induced by ionizing radiation (2) the processing, and (3) biological consequences of non-DSB clustered DNA damage. (author)

UV and ionizing radiations induced DNA damage, differences and similarities

Science.gov (United States)

Ravanat, Jean-Luc; Douki, Thierry

2016-11-01

Both UV and ionizing radiations damage DNA. Two main mechanisms, so-called direct and indirect pathways, are involved in the degradation of DNA induced by ionizing radiations. The direct effect of radiation corresponds to direct ionization of DNA (one electron ejection) whereas indirect effects are produced by reactive oxygen species generated through water radiolysis, including the highly reactive hydroxyl radicals, which damage DNA. UV (and visible) light damages DNA by again two distinct mechanisms. UVC and to a lesser extend UVB photons are directly absorbed by DNA bases, generating their excited states that are at the origin of the formation of pyrimidine dimers. UVA (and visible) light by interaction with endogenous or exogenous photosensitizers induce the formation of DNA damage through photosensitization reactions. The excited photosensitizer is able to induce either a one-electron oxidation of DNA (type I) or to produce singlet oxygen (type II) that reacts with DNA. In addition, through an energy transfer from the excited photosensitizer to DNA bases (sometime called type III mechanism) formation of pyrimidine dimers could be produced. Interestingly it has been shown recently that pyrimidine dimers are also produced by direct absorption of UVA light by DNA, even if absorption of DNA bases at these wavelengths is very low. It should be stressed that some excited photosensitizers (such as psoralens) could add directly to DNA bases to generate adducts. The review will described the differences and similarities in terms of damage formation (structure and mechanisms) between these two physical genotoxic agents.

Study of interaction among silicon, lithium, oxygen and radiation-induced defects for radiation-hardened solar cells

Science.gov (United States)

Berman, P. A.

1973-01-01

In order to improve reliability and the useful lifetime of solar cell arrays for space use, a program was undertaken to develop radiation-hardened lithium-doped silicon solar cells. These cells were shown to be significantly more resistant to degradation by ionized particles than the presently used n-p nonlithium-doped silicon solar cells. The results of various analyses performed to develop a more complete understanding of the physics of the interaction among lithium, silicon, oxygen, and radiation-induced defects are presented. A discussion is given of those portions of the previous model of radiation damage annealing which were found to be in error and those portions which were upheld by these extensive investigations.

Radiation-induced Pulmonary Damage in Lung Cancer Patients

International Nuclear Information System (INIS)

Chung, Su Mi; Choi, Ihl Bohng; Kang, Mi Mun; Kim, In Ah; Shinn, Kyung Sub

1993-01-01

Purpose: A retrospective analysis was performed to evaluate the incidence of radiation induced lung damage after the radiation therapy for the patients with carcinoma of the lung. Method and Materials: Sixty-six patients with lung cancer (squamous cell carcinoma 27, adenocarcinoma 14, large cell carcinoma 2, small cell carcinoma 13, unknown 10) were treated with definitive, postoperative or palliative radiation therapy with or without chemotherapy between July 1987 and December 1991. There were 50 males and 16 females with median age of 63 years(range: 33-80 years). Total lung doses ranged from 500 to 6,660 cGy (median 3960 cGy) given in 2 to 38 fractions (median 20) over a range of 2 to 150 days (median 40 days) using 6 MV or 15 MV linear accelerator. To represent different fractionation schedules of equivalent biological effect, the estimated single dose(ED) model, ED=D·N-0.377·T-0.058 was used in which D was the lung dose in cGy, N was the number of fractions, and T was the overall treatment time in days. The range of ED was 370 to 1357. The endpoint was a visible increase in lung density within the irradiated volume on chest X-ray as observed independently by three diagnostic radiologists. Patients were grouped according to ED, treatment duration, treatment modality and age, and the percent incidence of pulmonary damage for each group was determined. Result: In 40 of 66 patients, radiation induced change was seen on chest radiographs between 11 days and 314 days after initiation of radiation therapy. The incidence of radiation pneumonitis was increased according to increased ED, which was statistically significant (p=0.001). Roentgenographic charges consistent with radiation pneumonitis were seen in 100% of patients receiving radiotherapy after lobectomy or pneumonectomy, which was not statistically significant. In 32 patients who also received chemotherapy, there was no difference in the incidence of radiation induced charge between the group with radiation

The Assessment of Primary DNA Damage in Medical Personnel Occupationally Exposed to Ionizing Radiation

International Nuclear Information System (INIS)

Kopjar, N.; Garaj-Vrhovac, V.

2003-01-01

In physico-chemical interaction with cellular DNA ionizing radiation produces a variety of primary lesions, such as single-strand breaks (SSB), alkali-labile sites, double-strand breaks (DSB), DNA-DNA and DNA-protein crosslinks, and damage to purine and pyrimidine bases. The effects of low-level exposure to ionising radiation are of concern to large number of people, including workers receiving radiation exposure on the job. It is very important to estimate absorbed doses from individuals occupationally exposed to ionising radiation for carrying out radioprotection procedures and restrict the hazards to human health. A wide range of methods is presently used for the detection of early biological effects of DNA-damaging agents in environmental and occupational settings. Currently, unstable chromosomal aberrations in peripheral blood lymphocytes, in particularly dicentrics, are the most fully developed biological indicators of ionizing radiation exposure. This methodology usually complements data obtained by physical dosimetry. As a routine, it is used whenever the individual dosimeter shows an exposure to penetrating radiation above its limit of detection. One of the advantages of cytogenetic dosimetry is that this biological dosimeter can be assessed at any moment whereas physical dosimeters are not always present in the subject. During the last years, the single cell gel electrophoresis (SCGE) or comet assay has gained widespread acceptance for genotoxicity testing. In molecular epidemiology studies DNA damage evaluated by the comet assay is utilized as a biomarker of exposure. The comet assay permits the detection of primary DNA damage and the study of repair kinetics at the level of single cells. The aim of the present study was to assess and quantificate the levels of DNA damage in peripheral blood leukocytes of medical workers occupationally exposed to ionizing radiation and corresponding unexposed control subjects. As a sensitive biomarker of exposure the

\\title{Development of Radiation Damage Models for Irradiated Silicon Sensors Using TCAD Tools}

CERN Document Server

Bhardwaj, Ashutosh; Lalwani, Kavita; Ranjan, Kirti; Printz, Martin; Ranjeet, Ranjeet; Eber, Robert; Eichhorn, Thomas; Peltola, Timo Hannu Tapani

2014-01-01

Abstract. During the high luminosity upgrade of the LHC (HL-LHC) the CMS tracking system will face a more intense radiation environment than the present system was designed for. In order to design radiation tolerant silicon sensors for the future CMS tracker upgrade it is fundamental to complement the measurement with device simulation. This will help in both the understanding of the device performance and in the optimization of the design parameters. One of the important ingredients of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this paper we will discuss the development of a radiation damage model by using commercial TCAD packages (Silvaco and Synopsys), which successfully reproduce the recent measurements like leakage current, depletion voltage, interstrip capacitance and interstrip resistance, and provides an insight into the performance of irradiated silicon strip sensors.

Characterization of the implantation damage in SiO2 with x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Ajioka, T.; Ushio, S.

1986-01-01

X-ray photoelectron spectroscopy (XPS) has been applied to characterize the damage introduced into SiO 2 by ion implantation. By measuring the peak width of Si/sub 2p/ from SiO 2 which corresponds to perturbation of the SiO 2 network, good depth profiles of the damage have been obtained for implanted samples and subsequently annealed samples. The results show that the damage distributed more widely than that calculated from energy deposition and that the perturbation of the network is caused not only by radiation damage but also by the existence of impurities in the network. It has been found that the XPS method is effective to understand the atomic structure, and thus, electrical properties of SiO 2

On the fission track dating and annealing behaviour of accessory minerals of Eastern Ghats (Andhra Pradesh, India)

International Nuclear Information System (INIS)

Koul, S.L.

1978-01-01

Use of the etching of fission fragment damage tracks for an estimation of the uranium content of apatite and zircon crystals is described. The etching conditions have been studied for which visible tracks are developed. Fission track determined ages of 25 samples of apatite and zircon crystals from four widely separated regions of India; the Borra mines (Vishakapatanam), Kashipatnam (Vishakapatnam), the Khamam area (Andhra Pradesh) and the Kodrama mines (Bihar) have been determined. Mean ages for these regions are 456 +- 5, 389 +- 4, 486 +- 7 and 664 +- 7 million years respectively. It is concluded that the fission track ages of the minerals date the last metamorphic event of the Eastern Ghats, known as the Indian Ocean Cycle. Annealing studies confirm that radiation damaged fossil tracks can be erased in minerals under intense metamorphic episodes, thus resetting the geological clock. Extrapolation of the experimentally determined temperatures for annealing suggest that a temperature of 170 0 C in 10 6 years will erase all the tracks in the apatite mineral. The uranium concentration has been estimated to be approximately 10 -8 gm/gm in apatite and approximately 10 -6 gm/gm in zircon. (Auth.)

Radiation effects and damage formation in semiconductors due to high-energy ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Kamarou, A.

2006-11-07

The object of this thesis was the study of ion-beam induced damage formation and annealing in crystalline and conventionally predamaged Ge, GaAs, and InP. The samples were irradiated either at {approx}80 K or at room temperature with Kr, Xe, or Au ions with specific energy of about 0.3 MeV/u to 3 MeV/u. Thereafter the samples were studied by means of Rutherford backscattering spectroscopy and/or transmission electron microscopy.

Radiation effects and damage formation in semiconductors due to high-energy ion irradiation

International Nuclear Information System (INIS)

Kamarou, A.

2006-01-01

The object of this thesis was the study of ion-beam induced damage formation and annealing in crystalline and conventionally predamaged Ge, GaAs, and InP. The samples were irradiated either at ∼80 K or at room temperature with Kr, Xe, or Au ions with specific energy of about 0.3 MeV/u to 3 MeV/u. Thereafter the samples were studied by means of Rutherford backscattering spectroscopy and/or transmission electron microscopy

Increased radiation resistance in lithium-counterdoped silicon solar cells

Science.gov (United States)

Weinberg, I.; Swartz, C. K.; Mehta, S.

1984-01-01

Lithium-counterdoped n(+)p silicon solar cells are found to exhibit significantly increased radiation resistance to 1-MeV electron irradiation when compared to boron-doped n(+)p silicon solar cells. In addition to improved radiation resistance, considerable damage recovery by annealing is observed in the counterdoped cells at T less than or equal to 100 C. Deep level transient spectroscopy measurements are used to identify the defect whose removal results in the low-temperature aneal. It is suggested that the increased radiation resistance of the counterdoped cells is primarily due to interaction of the lithium with interstitial oxygen.

Comparison between cytogenetic damage induced in human lymphocytes by environmental chemicals or radiation

Energy Technology Data Exchange (ETDEWEB)

Cebulska-Wasilewska, A. [Institute of Nuclear Physics, Cracow (Poland)

1997-12-31

Author compared cytogenetic effects of chemicals (benzene and the member at benzene related compounds) and ionizing radiation on the human lymphocytes. Levels of various types of cytogenetic damage observed among people from petroleum plants workers groups are similar to the levels of damages detected in the blood of people suspected of the accidental exposure to a radiation source

Comparison between cytogenetic damage induced in human lymphocytes by environmental chemicals or radiation

International Nuclear Information System (INIS)

Cebulska-Wasilewska, A.

1997-01-01

Author compared cytogenetic effects of chemicals (benzene and the member at benzene related compounds) and ionizing radiation on the human lymphocytes. Levels of various types of cytogenetic damage observed among people from petroleum plants workers groups are similar to the levels of damages detected in the blood of people suspected of the accidental exposure to a radiation source

Radiation Damage in Silicon Detectors Caused by Hadronic and Electromagnetic Irradiation

CERN Document Server

Fretwurst, E.; Stahl, J.; Pintilie, I.

2002-01-01

The report contains various aspects of radiation damage in silicon detectors subjected to high intensity hadron and electromagnetic irradiation. It focuses on improvements for the foreseen LHC applications, employing oxygenation of silicon wafers during detector processing (result from CERN-RD48). An updated survey on hadron induced damage is given in the first article. Several improvements are outlined especially with respect to antiannealing problems associated with detector storage during LHC maintenance periods. Open questions are outlined in the final section, among which are a full understanding of differences found between proton and neutron induced damage, process related effects changing the radiation tolerance in addition to the oxygen content and the lack of understanding the changed detector properties on the basis of damage induced point and cluster defects. In addition to float zone silicon, so far entirely used for detector fabrication,Czochralski silicon was also studied and first promising re...

X-ray radiation damage studies and design of a silicon pixel sensor for science at the XFEL

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jiaguo

2013-06-15

Experiments at the European X-ray Free Electron Laser (XFEL) require silicon pixel sensors which can withstand X-ray doses up to 1 GGy. For the investigation of Xray radiation damage up to these high doses, MOS capacitors and gate-controlled diodes built on high resistivity n-doped silicon with crystal orientations left angle 100 right angle and left angle 111 right angle produced by four vendors, CiS, Hamamatsu, Canberra and Sintef have been irradiated with 12 keV X-rays at the DESY DORIS III synchrotron-light source. Using capacitance/ conductance-voltage, current-voltage and thermal dielectric relaxation current measurements, the densities of oxide charges and interface traps at the Si-SiO{sub 2} interface, and the surface-current densities have been determined as function of dose. Results indicate that the dose dependence of the oxide-charge density, the interface-trap density and the surface-current density depend on the crystal orientation and producer. In addition, the influence of the voltage applied to the gates of the MOS capacitor and the gate-controlled diode during X-ray irradiation on the oxide-charge density, the interface-trap density and the surface-current density has been investigated at doses of 100 kGy and 100 MGy. It is found that both strongly depend on the gate voltage if the electric field in the oxide points from the surface of the SiO{sub 2} to the Si-SiO{sub 2} interface. To verify the long-term stability of irradiated silicon sensors, annealing studies have been performed at 60 C and 80 C on MOS capacitors and gate-controlled diodes irradiated to 5 MGy as well, and the annealing kinetics of oxide charges and surface current were determined. Moreover, the macroscopic electrical properties of segmented sensors have slao been investigated as function of dose. It is found that the defects introduced by X-rays increase the full depletion voltage, the surface leakage current and the inter-electrode capacitance of the segmented sensor. An

X-ray radiation damage studies and design of a silicon pixel sensor for science at the XFEL

International Nuclear Information System (INIS)

Zhang, Jiaguo

2013-06-01

Experiments at the European X-ray Free Electron Laser (XFEL) require silicon pixel sensors which can withstand X-ray doses up to 1 GGy. For the investigation of Xray radiation damage up to these high doses, MOS capacitors and gate-controlled diodes built on high resistivity n-doped silicon with crystal orientations left angle 100 right angle and left angle 111 right angle produced by four vendors, CiS, Hamamatsu, Canberra and Sintef have been irradiated with 12 keV X-rays at the DESY DORIS III synchrotron-light source. Using capacitance/ conductance-voltage, current-voltage and thermal dielectric relaxation current measurements, the densities of oxide charges and interface traps at the Si-SiO 2 interface, and the surface-current densities have been determined as function of dose. Results indicate that the dose dependence of the oxide-charge density, the interface-trap density and the surface-current density depend on the crystal orientation and producer. In addition, the influence of the voltage applied to the gates of the MOS capacitor and the gate-controlled diode during X-ray irradiation on the oxide-charge density, the interface-trap density and the surface-current density has been investigated at doses of 100 kGy and 100 MGy. It is found that both strongly depend on the gate voltage if the electric field in the oxide points from the surface of the SiO 2 to the Si-SiO 2 interface. To verify the long-term stability of irradiated silicon sensors, annealing studies have been performed at 60 C and 80 C on MOS capacitors and gate-controlled diodes irradiated to 5 MGy as well, and the annealing kinetics of oxide charges and surface current were determined. Moreover, the macroscopic electrical properties of segmented sensors have slao been investigated as function of dose. It is found that the defects introduced by X-rays increase the full depletion voltage, the surface leakage current and the inter-electrode capacitance of the segmented sensor. An electron

Quantification of complex DNA damage by ionising radiation. An experimental and theoretical approach

International Nuclear Information System (INIS)

Fulford, J.

2000-05-01

Ionising radiation potentially produces a broad spectrum of damage in DNA including single and double strand breaks (ssb and dsb) and base damages. It has been hypothesised that sites of complex damage within cellular DNA have particular biological significance due to an associated decreased efficiency in repair. The aim of this study is to gain further understanding of the formation of complex DNA damage. Irradiations of plasmid DNA illustrate that an increase in ionising density of the radiation results in a decrease in ssb yields/Gy but an increase in dsb per ssb, indicative of an increase in the number of complex damage sites per simple isolated damage site. As the mechanism for damage formation shifts from purely indirect at low scavenging capacities to a significant proportion of direct at higher scavenging capacities the proportion of complex damage increases. Comparisons with the yields of ssb and dsb simulated by Monte-Carlo calculations for Al K USX and α-particles also indicate this correspondence. The ionisation density of low energy, secondary electrons produced by photons was assessed experimentally from the dependence of the yield of OH radicals escaping intra-track recombination on photon energy. As energy decreases the OH radical yield initially decreases reflecting an increased ionisation density. However, with further decrease in photon energy the yield of OH radicals increases in line with theoretical calculations. Base damage yields were determined for low and high ionising density radiation over a range of scavenging capacities. As scavenging capacity increases the base damage: ssb ratios increases implying a contribution from electrons to base damage. It is proposed that base damage contributes to DNA damage complexity. Complex damage analysis reveals that at cell mimetic scavenging capacities, 23% and 72% of ssb have an additional spatially close damage site following γ-ray and α-particle irradiation respectively. (author)

Jagiellonian University Radiation Damage in Silicon Particle Detectors in High Luminosity Experiments

CERN Document Server

Oblakowska-Mucha, A

2017-01-01

Radiation damage is nowadays the most serious problem in silicon particle detectors placed in the very harsh radiation environment. This problem will be even more pronounced after the LHC Upgrade because of extremely strong particle fluences never encountered before. In this review, a few aspects of radiation damage in silicon trackers are presented. Among them, the change in the silicon lattice and its influence on the detector performance are discussed. Currently applied solutions and the new ideas for future experiments will be also shown. Most of the results presented in this summary were obtained within the RD50 Collaboration

Modification of radiation damage by naturally occurring substances

International Nuclear Information System (INIS)

Prasad, K.N.

1984-01-01

The major objectives of studying the modification of radiation sensitivity have been (1) to identify a compound that will produce a differential protection or sensitization of the effect of irradiation on normal and tumor tissue, and (2) to understand more about the mechanisms of radiation damage. In spite of massive research on this particular problem since World War II, the first objective remains elusive. During this period, numerous radioprotective and radiosensitizing agents have been identified. These agents have served as important biologic tools for increasing our understanding of radiation injuries. Most of these substances are synthetic compounds and are very toxic to humans. In addition, very few of the compounds provide differential modifications of the effect of radiation on tumor and normal cells. This chapter presents objectives for identifying naturally occurring substances that modify the effect of x-radiation on mammalian cells and discusses the role of physiologic substances in modifying radiation injuries on mammalian normal and tumor cells

MagRad: A code to optimize the operation of superconducting magnets in a radiation environment

International Nuclear Information System (INIS)

Yeaw, C.T.

1995-01-01

A powerful computational tool, called MagRad, has been developed which optimizes magnet design for operation in radiation fields. Specifically, MagRad has been used for the analysis and design modification of the cable-in-conduit conductors of the TF magnet systems in fusion reactor designs. Since the TF magnets must operate in a radiation environment which damages the material components of the conductor and degrades their performance, the optimization of conductor design must account not only for start-up magnet performance, but also shut-down performance. The degradation in performance consists primarily of three effects: reduced stability margin of the conductor; a transition out of the well-cooled operating regime; and an increased maximum quench temperature attained in the conductor. Full analysis of the magnet performance over the lifetime of the reactor includes: radiation damage to the conductor, stability, protection, steady state heat removal, shielding effectiveness, optimal annealing schedules, and finally costing of the magnet and reactor. Free variables include primary and secondary conductor geometric and compositional parameters, as well as fusion reactor parameters. A means of dealing with the radiation damage to the conductor, namely high temperature superconductor anneals, is proposed, examined, and demonstrated to be both technically feasible and cost effective. Additionally, two relevant reactor designs (ITER CDA and ARIES-II/IV) have been analyzed. Upon addition of pure copper strands to the cable, the ITER CDA TF magnet design was found to be marginally acceptable, although much room for both performance improvement and cost reduction exists. A cost reduction of 10-15% of the capital cost of the reactor can be achieved by adopting a suitable superconductor annealing schedule. In both of these reactor analyses, the performance predictive capability of MagRad and its associated costing techniques have been demonstrated

Clustered DNA damages induced in isolated DNA and in human cells by low doses of ionizing radiation

Science.gov (United States)

Sutherland, B. M.; Bennett, P. V.; Sidorkina, O.; Laval, J.; Lowenstein, D. I. (Principal Investigator)

2000-01-01

Clustered DNA damages-two or more closely spaced damages (strand breaks, abasic sites, or oxidized bases) on opposing strands-are suspects as critical lesions producing lethal and mutagenic effects of ionizing radiation. However, as a result of the lack of methods for measuring damage clusters induced by ionizing radiation in genomic DNA, neither the frequencies of their production by physiological doses of radiation, nor their repairability, nor their biological effects are known. On the basis of methods that we developed for quantitating damages in large DNAs, we have devised and validated a way of measuring ionizing radiation-induced clustered lesions in genomic DNA, including DNA from human cells. DNA is treated with an endonuclease that induces a single-strand cleavage at an oxidized base or abasic site. If there are two closely spaced damages on opposing strands, such cleavage will reduce the size of the DNA on a nondenaturing gel. We show that ionizing radiation does induce clustered DNA damages containing abasic sites, oxidized purines, or oxidized pyrimidines. Further, the frequency of each of these cluster classes is comparable to that of frank double-strand breaks; among all complex damages induced by ionizing radiation, double-strand breaks are only about 20%, with other clustered damage constituting some 80%. We also show that even low doses (0.1-1 Gy) of high linear energy transfer ionizing radiation induce clustered damages in human cells.

Functional analysis of molecular mechanisms of radiation induced apoptosis, that are not mediated by DNA damages

International Nuclear Information System (INIS)

Angermeier, Marita; Moertl, Simone

2012-01-01

The effects of low-dose irradiation pose new challenges on the radiation protection efforts. Enhanced cellular radiation sensitivity is displayed by disturbed cellular reactions and resulting damage like cell cycle arrest, DNA repair and apoptosis. Apoptosis serves as genetically determinate parameter for the individual radiation sensitivity. In the frame of the project the radiation-induced apoptosis was mechanistically investigated. Since ionizing radiation induced direct DNA damage and generates a reactive oxygen species, the main focus of the research was the differentiation and weighting of DNA damage mediated apoptosis and apoptosis caused by the reactive oxygen species (ROS).

Protection from ionizing radiation induced damages by phytoceuticals and nutraceuticals

International Nuclear Information System (INIS)

Nair, C.K.K.

2012-01-01

Exposure of living systems to ionizing radiation cause a variety of damages to DNA and membranes due to generation of free radicals and reactive oxygen species. The radiation induced lesions in the cellular DNA are mainly strand breaks, damage to sugar moiety, alterations and elimination of bases, cross links of the intra and inter strand type and cross links to proteins while peroxidation of the lipids and oxidation of proteins constitute the major lesions in the membranes. The radioprotectors elicit their action by various mechanisms such as i) by suppressing the formation of reactive species, ii) detoxification of radiation induced species, iii) target stabilization and iv) enhancing the repair and recovery processes. The radioprotective compounds are of importance in medical, industrial, environmental, military and space science applications. Radiation protection might offer a tactical advantage on the battlefield in the event of a nuclear warfare. Radioprotectors might reduce the cancer risk to populations exposed to radiations directly or indirectly through industrial and military applications. The antioxidant and radioprotective properties a few of these agents under in vitro and in vivo conditions in animal models will be discussed

Thermal annealing of an embrittled reactor pressure vessel

International Nuclear Information System (INIS)

Mager, T.R.; Dragunov, Y.G.; Leitz, C.

1998-01-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. Chapter 11 deals with thermal annealing of an embrittled reactor pressure vessel. Anneal procedures for vessels from both the US and the former USSR are mentioned schematically, wet anneals at lower temperature and dry anneals above RPV design temperatures are investigated. It is shown that heat treatment is a means of recovering mechanical properties which were degraded by neutron radiation exposure, thus assuring reactor pressure vessel compliance with regulatory requirements

Ion bombardment simulation: a review related to fusion radiation damage

International Nuclear Information System (INIS)

Brimhall, J.L.

1975-01-01

Prime emphasis is given to reviewing the ion bombardment data on the refractory metals molybdenum, niobium and vanadium which have been proposed for use in advanced fusion devices. The temperature and dose dependence of the void parameters are correlated among these metals. The effect of helium and hydrogen gas on the void parameters is also included. The similarities and differences of the response of these materials to high dose, high temperature radiation damage are evaluated. Comparisons are made with results obtained from stainless steel and nickel base alloys. The ion bombardment data is then compared and correlated, as far as possible, with existing neutron data on the refractory metals. The theoretically calculated damage state produced by neutrons and ions is also briefly discussed and compared to experimental data wherever possible. The advantages and limitations of ion simulation in relation to fusion radiation damage are finally summarized