Sources Of Ionizing Radiation Research Articles

A cautionary tale of soft errors induced by SRAM packaging materials

Modern implantable medical devices use a variety of circuit and architectural features to ensure high levels of data integrity, especially data related to patient therapies and safety. Since modern implantable medical devices, such as implantable cardioverter defibrillators (ICDs) and pacemakers, rely on integrated-circuit (IC) technology, they are susceptible to soft errors from ionizing radiation sources. The IC technology employed in implantable devices typically uses a CMOS technology that is several generations behind the most advanced CMOS processes due to the overwhelming concern of transistor leakage, power consumption, and reliability requirements. For CMOS technology and modern circuit design processes, IC susceptibility to alpha-particle radiation is a known concern. For power consumption requirements, the operating voltages of implantable medical devices are also typically lower than standard electronic products, so this can have a much greater impact of alpha-induced soft-error rates (SERs). This paper will detail a case study performed on a new SRAM package, potentially for collecting diagnostic data, in which a variety of test methods was used to isolate materials contributing to alpha-induced soft errors. The test procedure utilized numerous standard SRAM components in a flip-chip configuration, with a test board to gather large amounts of data in a relatively short time period. SRAM test chips were also isolated from thermal neutrons by using a boron-shielded test chamber. Contributions from cosmic-ray-induced energetic neutrons were previously characterized and taken into account during the interpretation of the data. The correlation of soft errors to bump layout is shown with high-alpha-emitting materials, and the range of these errors is verified with modeling. The use of low-alpha-emitting solders and underfill materials for the reduction of soft errors will also be shown. Without underfill, residual errors from high-alpha-emitting solders, materials on the periphery of the circuit board, and the circuit board itself can be shown to impact the total SER of the system.

Co-activation of ERK, NF-κB, and GADD45β in Response to Ionizing Radiation

NF-kappaB has been well documented to play a critical role in signaling cell stress reactions. The extracellular signal-regulated kinase (ERK) regulates cell proliferation and survival. GADD45beta is a primary cell cycle element responsive to NF-kappaB activation in anti-apoptotic responses. The present study provides evidence demonstrating that NK-kappaB, ERK and GADD45beta are co-activated by ionizing radiation (IR) in a pattern of mutually dependence to increase cell survival. Stress conditions generated in human breast cancer MCF-7 cells by the administration of a single exposure of 5 Gy IR resulted in the activation of ERK but not p38 or JNK, along with an enhancement of the NF-kappaB transactivation and GADD45beta expression. Overexpression of dominant negative Erk (DN-Erk) or pre-exposure to ERK inhibitor PD98059 inhibited NF-kappaB. Transfection of dominant negative mutant IkappaB that blocks NF-kappaB nuclear translocation, inhibited ERK activity and GADD45beta expression and increased cell radiosensitivity. Interaction of p65 and ERK was visualized in living MCF-7 cells by bimolecular fluorescence complementation analysis. Antisense inhibition of GADD45beta strikingly blocked IR-induced NF-kappaB and ERK but not p38 and JNK. Overall, these results demonstrate a possibility that NF-kappaB, ERK, and GADD45beta are able to coordinate in a loop-like signaling network to defend cells against the cytotoxicity induced by ionizing radiation.

Development of monolithic active pixel detector in SOI technology

A novel solution of an active pixel detector, which exploits wafer-bonded Silicon on Insulator (SOI) substrates for integration of the readout electronics with the pixel detector, is presented. The main concepts of the proposed monolithic sensor and the preliminary tests results with ionising radiation sources are addressed. SOI is an alternative solution of a monolithic active pixel detector, which allows integrating fully depleted sensor and front-end electronics active layers into one silicon wafer. The main idea of the sensor relies on the use of both the monolithic silicon layers (device and support layers) of the SOI substrate for fabrication of pixel detector diodes and readout electronics. Such detectors can find a wide range of applications, not only in particle physics but also in medicine, space science and many other disciplines. The sensor structure and the readout configuration have been developed and the measurements of a dedicated test structure have validated the new technology of the SOI detector. Then small SOI sensor matrices with 8×8 channels have been recently produced and tested.

Effect of β-particles on the retinal chromophore in bacteriorhodopsin of Halobacterium salinarium

Bacteriorhodopsin (bR) is an attractive intelligent material. Understanding the mechanism of its light-driven proton pumping outward the cell implicates it in many technical applications, particularly, in what is called optical computers, and the biotechnology is waiting for this promised biological molecule. An ionizing radiation source handling could be computerized in radiation fields. The computer containing such biological material will not be out of reach of the fields of ionizing radiation. So it is interesting to report on the working of such biological computer if it is subjected to ionizing radiation. The functional unit in this molecule is retinal chromophore. In the present work, it is interested to assess the functionality of bR through determining the electronic transition dipole moment of its chromophore. Significant changes in the values of the absorption transition dipole moment were noticed at different doses of β-particles in the range of 0.1– 0.3 kGy . Ionizing radiation-induced changes in bR were followed by intrinsic fluorescence spectroscopy. An analysis of the fluorescence data bears on the tertiary structure of bR. The emission spectrum is, however, red shifted with an increase in intensity with the different doses; in the meanwhile, gradual decrease in the visible absorbance has occurred till almost complete loss is attained. This bleaching due to ionizing radiation may offer an alternative way of data processing in such optical devices based on bR. Nevertheless, bR has proofed to be used as a biological indicator of ionizing radiation. However, the potential of bR for use as a biosensor to detect ionizing radiation should be considered.

Cure grafting—a complementary technique to preirradiation and simultaneous processes?

A novel radiation grafting process, termed cure grafting, based on curing of donor/acceptor (DA) monomers as charge transfer complexes initiated by UV or any ionising radiation source, is proposed. The system is complementary to the existing preirradiation and simultaneous radiation grafting methods. The advantages and disadvantages of cure grafting are summarised. Examples of cure grafting using representative DA monomers are described with cellulose as model substrate in the presence of UV or EB. A unique property of cure grafting is that the yield is known quantitatively prior to irradiation.

344. Radiobiological supplying of oncological patient radial therapy

The examination of radiobiological peculiarities of therapeutic ionizing radiation source action gives an opportunity of preferable choice of exposure requirements of the oncological patients. The therapeutic ionizing radiation source, inlet into operation, should pass radiobiological examination, including with the purpose of definition of relative biological effectiveness (RBE) depending on quality, radiation dose, radiosensitiveness of cells etc. The cytogenetic dosimetry is carried out at an exposure of man Iymphocyte culture the on therapeutic source 137Cs, 60Co, neutrons with average energy 6 and 22 MeV. Is shown that isoeffective distribution of the neutron energy does not correspond with physical isodose distribution allowing for RBE constant value. For the first time is shown that for optimization of patient exposure therapeutic effect rationally to use neutron RBE variable values. For the first time is shown that RBE value of 137Cs gamma-quantum used for intracavitary radiotherapy, exceed 1 (in comparison with 60Co) and in dose range 0,15 – 5,0 Gy makes 3,5 – 1,2 accordingly. The method of approximating of association “dose - effect” on basis of spline regression which is characterized by smaller values of model parameter errors for various cytogenetic indexs and enables to forecast effect of calibrating curve outlet on a plateau is designed and proposed. The dose curves for RBE definition of therapeutic ionizing radiation source on the basis of spline regression model have to be taken into consideration for decrease of frequency and expressiveness of radiocomplications at an oncological patient exposure.

Radiofrequency Gaseous Detection Device.

A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

A radioluminescence study of spectral and dose characteristics of common luminophors.

Many synthetic materials are used as thermoluminescence dosemeters for the measurement of the absorbed dose from ionising radiation sources. A part of the absorbed energy leads to a prompt luminescence (radioluminescence, abbreviated RL) which dose behaviour mainly corresponds with the densitity of charge carriers in the respective traps or recombination sites. The RL reported in this study was stimulated using two 137Cs sources with activities of 3.7 MBq (spectral measurements) or 5 MBq (dosimetry studies), respectively, and was recorded steadily during stimulation. This presentation gives a comprehensive survey of the spectral and dose dependent RL properties of a number of luminescent materials like LiF:Mg,Ti, Al2O3:C, CaSO4:Dy, CaF2:Mn, Li2B4O7:Mn, BeO and ZnS:Ag. The spectral and dose dependent results were compared with thermoluminescence as well as other RL studies.

The studies on radiological limits of color-glazed tiles used in home decoration.

This study was carried out to lay down the radiological limits of color-glazed tiles used in home decoration. The activity concentrations of various end products and raw materials as well as processed materials were measured using gamma spectroscopy. 222Rn exhalation rates from the surface of color-glazed tiles were measured using charcoal canister method. Levels of exposure to alpha ray and beta ray from the surface of glazed tiles were measured by surface alpha and beta contaminant instrument. The results show a great difference between the radioactive levels of the surface glaze and the matrix of color-glazed tiles. The 222Rn exhalation rates from the surface of color-glazed tiles are in the range of 10(-3) - 10(-4) Bq m(-2) s(-1). The concentrations of some natural radionuclides in glaze exceed the exempt limits of International Basic Safety Standards for Protection against Ionizing Radiation Sources (IAEA 1997). The limits for color-glazed tiles were deduced according to these data and the theory of UNSCEAR (1993). The activity concentration of 226Ra (Bq kg(-1)) in the glaze of color-glazed tiles should be in the range of A(226Ra) < or = 1,000 (Bq kg(-1)), and, at the same time, the specific activity of the natural radionuclides (Bq kg(-1)) should be in the range of A(232Th)/230 + A(226Ra)/310 + A(40K)/3,500 < or = 1.

Low field leakage current and soft breakdown in ultra-thin gate oxides after heavy ions, electron or X-ray irradiation

The excess leakage current across ultra-thin dielectrics has been studied for different ionizing radiation sources. Namely, X-rays, 8 MeV electrons, and three ion beams with different LETs values have been used on large area MOS capacitors with 4-nm thick oxides. Small oxide fields were applied during irradiation, reaching 3 MV/cm at most. For ionizing radiation with relatively low LET (<10 MeV cm/sup 2//mg), only Radiation Induced Leakage Current (RILC) was observed, due to the formation of neutral defects mediating electron tunneling via a single oxide trap. For high LET values, instead, the gate leakage current could be described by an empirical relation proper of Soft Breakdown (SB) phenomena detected after electrical stress. Moreover, the typical random telegraph signal noise feature of this Radiation induced Soft Breakdown (RSB) currents was observed during and after irradiation. RSB can be attributed to conduction through a multi-defect path across the oxide, produced by the residual damage of dense ion tracks. The oxide field applied during irradiation enhances the RSB intensity, but RSB can be achieved even for irradiation at zero field, being LET the main factor leading to RSB activation. The dose dependence of both RILC and QB have been investigated, showing a quasi linear kinetics with the cumulative dose. We have also studied the effect of modifying the angle of incidence of the ion beam on the intensity of the gate leakage current.

Significance of grafting in curing processes initiated by UV, excimer and ionising radiation sources

The grafting of a typical methacrylate monomer (MMA) to polypropylene (PPE) and cellulose initiated by UV and ionising radiation is reported. The effect of additives which constitute components in radiation curing on the grafting process is examined. Additives studied include photoinitiators (PIs), multifunctional acrylates and methacrylates and acrylate oligomers. Synergistic effects when these additives are combined in the same solution are reported. The photografting studies have been extended to include grafting with charge transfer (CT) complexes involving donor/acceptor (DA) monomers to PPE, cellulose and wool. The importance of this work in conventional and PI free curing is discussed, particularly the significance of concurrent grafting during curing.

Current status of the application of ionizing radiation to environmental protection: I. Ionizing radiation sources, natural and drinking water purification (A Review)

Present-day applications of ionizing radiation to environmental protection are surveyed. This part of the review summarizes new data on the ionizing radiation sources used in this area, on the radiation-chemical purification of polluted natural and drinking water, and on the mechanisms of processes occurring in these systems under exposure to ionizing radiation. A particular emphasis is placed on large-scale processes.

Radiofrequency Gaseous Detection Device

A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

Radiofrequency Gaseous Detection Device

Abstract A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

Transport Data Collection and Reporting in the Czech Republic

AbstractThe State Office for Nuclear Safety (SONS) as the responsible body for the safe transport of radioactive materials in the Czech Republic is required to maintain a national system for registration of: (i) the approvals of special form radioactive material, package designs and shipments; (ii) the records of exposure of persons coming into contact with ionising radiation sources at their work (including radiation exposures resulting from radioactive material transport); and (iii) the reports on radiological accidents (including reports on accidents in radioactive material transport). The system is described of registration of the above mentioned items in the Czech Republic following on from the obligations of the SONS stipulated in the Act No. 18/1997 on Peaceful Utilization of Nuclear Energy and Ionizing Radiation Act (‘Atomic Act’). The importance of the International Atomic Energy Agency databases PACKTRAM, SHITPTRAM, EXTRAM, EVTRAM and REDTRAM is discussed from SONS point of view.

Update on Lower Extremity Endovascular Interventions

In the past decade there have been major strides in the development of devices and techniques for nonsurgical lower extremity revascularization. These advances have broadened indications for endovascular therapies and expanded the treatment options for patients with peripheral vascular disease. A variety of new laser‐etched steel and nitinol stent designs now complement balloon angioplasty. In the iliac segment, stenting has replaced balloon angioplasty as the first‐line therapy for treatment of symptomatic occlusive disease. Stenting results in superior acute procedural success and long‐term clinical efficacy compared to balloon angioplasty and is a “less invasive” alternative to surgical reconstruction. Endoluminal stent grafts offer promise in the treatment of high‐risk patients with abdominal aortic aneurysms. New strategies are being developed to address the diverse nature of the superficial femoral artery (SFA) and infrapopliteal disease where balloon angioplasty, stenting, and stent graft strategies have proven unsatisfactory for treatment of diffuse disease and long occlusions. The next millennium will see the use of “therapeutic angiogenesis,” the intravascular and intramuscular administration of DNA fragments or proteins, to stimulate new vessel growth in patients not amenable to conventional surgical or endovascular therapies. Brachytherapy, the intravascular delivery of a retrievable ionizing radiation source, represents an exciting development that offers the potential of reducing restenosis in the SFA.

Use of neutron-activation techniques for studying elemental distributions. Applications to geochemistry

The radiography method was developed for the investigation of the distribution of ionizing radiation sources on a sample surface by means of a two-dimensional image, produced in a photoemulsion or dielectric track detector. Its sensitivity is within the range 10−2–10−7gmm−2 with a resolution of from 0.01 to 100μm. Statistical analysis and computer processing of the radiographic images have allowed us to solve the two main tasks of the method, namely the determination of the true distributions of ionizing radiation sources on a surface and the quantitative estimation of the local content of different chemical elements within a given accuracy.

Use of neutron-activation techniques for studying elemental distributions: applications in geochemistry, ecology and technology

The radiography method is developed for the investigation of ionizing radiation sources distribution on the sample surface by means of a two-dimensional image, produced in a photoemulsion or dielectric track detector. Its sensitivity is within a range of 10 −2 - 10 −7 g/mm 2 and resolution from 0.01 to 100 μm. Statistical analysis and computer processing of the radiographic images have allowed us to solve the two main tasks of the method, namely, the determination the true distributions of ionizing radiation sources on the surface and the quantitative estimation of the local content of different chemical elements within a given accuracy.

Effect of irradiation spectrum on the microstructural evolution in ceramic insulators

Cross section transmission electron microscopy has been used to investigate the microstructure of MgAl 2O 4 (spinel) and Al 2O 3 (alumina) following irradiation with ions of varying mass and energy at room temperature and 650°C. Dislocation loop formation was suppressed in specimens irradiated with light ions, particularly in the case of spinel. An evaluation of the data showed that dislocation loop formation during irradiation at 650°C was suppressed when the ratio of the electronic- to nuclear -stopping power was greater than ∼ 10 and ∼ 1000 for spinel and alumina, respectively. These results clearly indicate that light ion and electron irradiations produce microstructures which are not representative of the microstructure that would form in these ceramics during fission or fusion neutron irradiation. The absence of observable dislocation loops following energetic light ion irradiation is believed to be due to ionization-enhanced diffusion effects, which promote point defect recombination. The effect of uniform background levels of ionizing radiation on the microstructural evolution in spinel was investigated by performing simultaneous dual-beam (He + and heavy ion) irradiations. The uniform ionizing radiation source did not affect the microstructural evolution of spinel unless the ionization was very intense (average electronic- to nuclear-stopping power ratio > 100).

Reliability assessment of CCDs operating under ionizing radiation ambients: Failure — Simulation studies via electrical overstressing

This paper addresses a study on simulated space radiation effects on charge-coupled devices (CCD). An implicit method of assessing the performance degradation and field reliability of CCDs operated in natural ionizing-radiation ambients is devised via test studies using an electrical overstress parameter to represent the ionizing radiation dosage equivalently. Relevant cumulative degradation due to accelerated aging performed on a set of commercially available CCD is analyzed to establish the endurance coefficient of device(s). The proposed method is devoid of handling hazardous ionizing radiation sources and also enables fast reliability predictions. The test results are discussed.