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SOLAR ACTIVITY AND OZONE LAYER DEPLETION COMPARISION OF PARAMETRIC EVALUATION OF TOTAL OZONE MAPPING SPECTROPHOTOMETER (TOMS) DATA NIMBUS -7 WITH THE DOBSON SPECTROPHOTOMETER OBSERVATIONS AT THE GEOPHYSICAL CENTER QUETTA, PAKISTAN M.Ayub Khan Yousuf Zai, Jawaid Quamar,M.Rashid Kamal Ansari, Jawaid Iqbal and Arif Hussian Institute of Space and Planetary Astrophysics and Department of Applied Physics, University of Karachi Abstract In this communication we present some approaches to relate the depletion process with the solar activity. We propose to study the effectiveness of ozone layer structure. Developing a quantitative treatment for data covering a specific period, this study will report for Pakistan an explorative assessment of the link between ozone layer depletion and solar activity. We have computed parameters, which signify the measurements drawn from the satellite, and ground based instruments. We will also try to look for understanding the interaction of dynamics and ozone photochemistry in the middle atmosphere ( 25-35 km) and the nature of stratospheric responses to anomalous solar activity. We have compared both the data sets using different techniques and observed that the trend follows the same path. This could be helpful in obtaining the estimates of sunspots and establishing a correlation with the ozone layer reduction then suitable predictions can be made for our government and private departments Introduction Solar studies are of importance in general astronomy because the sun is the only star upon which surface detail an be resolved The investigators find the variety of solar structures and events to decide their physical causes. For our society, the study of the sun is more indirect but of great importance because solar radiation is essential to our biosphere. Cyclicity of solar activity (solar cycle) could be a factor supporting the emergence of OLD (Solar terrestrial relations analysis). It is suspected that Cl 2 is produced during active period of the sun and this production of Cl 2 causes Ozone layer depletion. The rates of ozone removal in the year 1992 are enhanced by volcanic eruptions in 1991 and 1992. Because anthropogenically introduced chlorine(Cl) and bromine(Br) levels will remain high for so long, it is expected that there will be

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Page 1: SOLAR ACTIVITY AND OZONE LAYER DEPLETION · 2011-02-06 · solar activity and ozone layer depletion comparision of parametric evaluation of total ozone mapping spectrophotometer (toms)

SOLAR ACTIVITY AND OZONE LAYER DEPLETION COMPARISION OF PARAMETRIC

EVALUATION OF TOTAL OZONE MAPPING SPECTROPHOTOMETER (TOMS) DATA

NIMBUS -7 WITH THE DOBSON SPECTROPHOTOMETER OBSERVATIONS AT

THE GEOPHYSICAL CENTER QUETTA, PAKISTAN

M.Ayub Khan Yousuf Zai, Jawaid Quamar,M.Rashid Kamal Ansari, Jawaid

Iqbal and Arif Hussian Institute of Space and Planetary Astrophysics and Department of Applied

Physics, University of Karachi

Abstract In this communication we present some approaches to relate the depletion process with the solar activity. We propose to study the effectiveness of ozone layer structure. Developing a quantitative treatment for data covering a specific period, this study will report for Pakistan an explorative assessment of the link between ozone layer depletion and solar activity. We have computed parameters, which signify the measurements drawn from the satellite, and ground based instruments. We will also try to look for understanding the interaction of dynamics and ozone photochemistry in the middle atmosphere ( 25-35 km) and the nature of stratospheric responses to anomalous solar activity. We have compared both the data sets using different techniques and observed that the trend follows the same path. This could be helpful in obtaining the estimates of sunspots and establishing a correlation with the ozone layer reduction then suitable predictions can be made for our government and private departments Introduction Solar studies are of importance in general astronomy because the sun is the only star upon which surface detail an be resolved The investigators find the variety of solar structures and events to decide their physical causes. For our society, the study of the sun is more indirect but of great importance because solar radiation is essential to our biosphere. Cyclicity of solar activity (solar cycle) could be a factor supporting the emergence of OLD (Solar terrestrial relations analysis). It is suspected that Cl2 is produced during active period of the sun and this production of Cl2 causes Ozone layer depletion. The rates of ozone removal in the year 1992 are enhanced by volcanic eruptions in 1991 and 1992. Because anthropogenically introduced chlorine(Cl) and bromine(Br) levels will remain high for so long, it is expected that there will be

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more and more UV-B reaching the earth’s surface. Man-made causes of OLD are providing a threshold for OLD. We can not neglect the natural events which are occurring in the upper atmosphere and producing certain chemical constituents which react with O3 and dissociate it into nascent oxygen and a molecular oxygen an can be seen by Chapman reactions. Therefore, in view of this conception the Montreal Protocol is not to be all of the things.[1-8]. These investigations led to series of processes known as Chapman mechanism which explained the formation and annihilation of O3 layer. Using this mechanism, predictions were made which provided excellent agreement with observations available then [30-35]. The situation can be explained by the following reactions:

O2 + h ν → O + O (1) O + O2 + M → O3 + M (2) O3 + hν → O + O2 (3) O + O3 → O2 + O2 (4)

M being a third body required carrying off the excess energy of the association process. The rapid cycle composed of reaction (1.2) and (1.3) does not, of course, destroy O3. Many years after the preceding initial work, it was suggested that catalytic processes can lead to the overall reaction as follows: O + O3 → 2 O2 (5) Ozone content in the stratosphere varies due to various natural and anthropogenic activities. Some prominent such activities creating OLD are described as follows (a) Technological CFCs produced in various technological processes gradually migrate upward into the stratosphere. At altitude above 30 km, intense UV radiation breaks down the CFCs, causing them to release chlorine and destroying ozone as shown in the following chemical reactions:

CFCl3 + h ν → CF Cl2 + Cl − (6) CF2Cl2 + h ν→ CF2 Cl + Cl (7)

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Cl + O3 → Cl O + O2 (8)

During the past few years, satellite and ground-based observations have particularly contributed to our understanding of the general features of the vertical ozone distribution and latitude variations in the stratosphere and lower mesosphere. Ozone photochemistry in the middle atmosphere (25-35 km) will contribute to link stratospheric responses to anomalous solar activity (b) Solar Cycle In the stratosphere sun drives the photochemistry as well as providing the heating that drives the solar circulation. Because the atmosphere absorbs UV and shorter wavelength radiation, accurate determination of its time variation should be measured from above the top of the atmosphere. Some information about solar variability can be obtained by consideration of longer wavelength features that do penetrate to the ground, as the same mechanisms that give rise to the longer-wavelength variations the most often is the radio radiation with a 10.7-micron wavelength, albeit the other proxies such as sunspot numbers can also be used. Two of the most important periods for solar variations are 27 days and 11 years.[9-22] The solar cycle dependence of atmospheric ozone also has an altitude dependence which maximises at approximately 45 km. The temperature changes of the upper stratsphere are rather caused by the solar cycle variation. Basis for the solar cycle theory was the notion that reactive nitrogen compounds (NO and NO2), like chlorine can destroy stratospheric ozone quite effectively. These compounds are produced in abundance in the mesosphere and lower thermosphere (∼ 60-70 km) during period of high solar activity. The nitrogen compounds are rapidly destroyed in the mesosphere, but might be transported all to the stratosphere in the dark polar winter. (c) Solar Proton Events Sometimes the sun emits large amount of protons which are channeled by the earth’s magnetic field to impact the earth at high altitudes. These are referred to as solar proton events (SPEs). For protons of sufficient energy, they can reach the mesosphere and stratosphere and lead to reduction of ozone by producing increased concentrations of odd nitrogen and / or odd hydrogen compounds in the stratosphere. A principal advance in the determination of ozone distributions and variability came with the advent of satellite-based systems. The most important of these are given as follows: (1) Total Ozone Mapping Spectrometer (TOMS) instruments for total ozone measurements (2) Solar Backscatter Ultraviolet (SBUV,I and II ) (3) Stratosphere Aerosol and Gas Experiment (SAGE, I andII) instruments for vertical ozone distributions

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(d) Investigating the correlations between the UV-B due to OLD and the solar variations using modeling strategies

sunspot

y=279.266+0.051*x+eps

Sun spot numbers (Counts)

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Figure.1. Correlation between ozone concentration and the sunspot numbers Measurements from satellite can give near-global covering, however, it provides only averaged values of the measured quantity over large distances both in vertical and horizontal directions. So we have preferably utilised Dobson data for our computations and compared these with the data. down loaded from satellite (TOMS, Nimbus-7 ). As far as the trend and cumulative behaviour of TOMS satellite data and Dobson data measured with the help of ODD spectrophotometer that was installed at Geophysical Center Quetta for the duration 1979-1993 are concerned we have tried to demonstrate through precise computations the comparison between these two data sets. International Ozone Network presently utilizes ozone depth detecting spectrophotometer (ODDS). On board the satellite, incident solar radiation and backscattered UV sunlight are measured. Total ozone is derived from these measurements. To map total ozone, total ozone mapping spectrometer (TOMS) instrument scan through the sub-satellite point in a direction perpendicular to the orbit plane [18][23]. Details of these instruments could be found in every ozone detection techniques literature. Satellite-borne instruments (e.g. on Nimbus-7, Meteor-3, ADEOS and Earth’s probe) are used to measure decreases in the concentration of stratospheric

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ozone in our atmosphere. Total Ozone Mapping Spectrometer (TOMS) data (Nimbus-7) are available for the period from 1979-1993. A comparison TOMS and Dobson values using coefficient of variation (CV) for each year of both the data sets, observing trends and calculating some other parameters is given in Table.1.

TABLE.1: Comparison of parametric computation for TOMS satellite and Dobson data during the session 1979-1993 and Dobson data during the session 1979-1993

Parameters

/ Years Mean of TOMS

/Dobson

X

TR – Mean TOMS /Dobson TR – X

Sta. Dev. TOMS

/Dobson σ

SE mean TOMS

/Dobson

SE- X

Coefficient of Variation TOMS

/Dobson (CV)

1979 285.76/ 298.25 284.18/296.32 23.01/21.79 1.30 / 6.29 0.08 / 0.07 1980 277.50/ 294.00 276.37/293.23 18.41/11.27 0.98 / 3.25 0.07 / 0.04 1981 280.89/291.50 279.62/ 290.45 16.85/13.32 0.88 / 3.84 0.06 / 0.05 1982 287.07/301.25 285.28/299.13 24.85/20.46 1.31/5.91 0.08 / 0.07 1983 272.55/283.92 271.64/281.34 18.45/8.93 0.97 / 2.56 0.07 / 0.03 1984 275.88/ 287.67 275.83/285.41 21.81/17.07 1.14/4.93 0.08 / 0.06 1985 262.09/ 277.42 262.15/276.21 12.71/ 6.68 0.67 / 1.93 0.05/ 0.02 1986 272.01/ 292.58 271.43/ 290.65 18.52/13.81 0.97 / 3.98 0.07 / 0.05 1987 270.81/ 286.92 271.12/ 285.22 23.12/20.64 1.21 / 5.96 0.08 / 0.07 1988 264.50/281.83 264.31/280.34 19.70/ 7.93 1.03/2.28 0.07 / 0.03 1989 279.62/297.75 279.13/280.34 15.43/10.57 0.81 / 3.05 0.05 / 0.04 1990 274.46/282.83 273.87/280.32 16.73/27.07 0.83 / 7.80 0.06 / 0.09 1991 280.25/297.83 280.23/295.11 20.52/15.39 1.08 / 4.44 0.07 / 0.05 1992 272.70/278.33 271.45/ 277.76 23.27/18.49 1.22 / 5.33 0.08 / 0.07 1993 262.54/264.92 262.77/ 263.22 18.10/5.82 1.61 / 1.68 0.06 / 0.02

TABLE. 2: Trend equations

1 TOMS-Nimbus – 7 Yt = 281.37 0 .85 t + ε 2 Dobson Instrument Yt = 297.23 1.179 t + ε

This justifies our adoption of Dobson data for computation and modeling. Data having less variation is more stable and vice versa. Coefficient of variation hence determines the stability or consistency of the data.

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NEWVAR18 (L)

NEWVAR19 (R)

Time in years (1979-1993)

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Figure. 2. Manifestation of the trends of TOMS and Dobson data sets

DOBSON (L)TOMS (R)

Time in years (1979-1993)

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Figure 3: Depiction of the trends of TOMS and Dobson data sets with 95 %

confidence level.

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DOBSON (L)

TOMS (R)

Time in years (1979-1993)

Tota

l Ozo

ne fr

om T

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Figure. 4: Comparison of ground-based data recorded at Quetta Pakistan on Dobson Spectrophotometer with the TOMS Nimbus-7

The trend equations are also evolved using least square methods as shown in table 2. These equations could be used for future predictions for both the data sets. Accuracy of the Dobson Unit (DU) is based on the laboratory measurements of the ozone absorption coefficients as mentioned above. An error in the absorption coefficients is due to the band pass and the solar spectral shape. The error in the measurements of the absolute DU scale can be estimated as ranging from 3 % to 5 %. Figure.5.

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250

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Jan Apr Aug De c Months

1982.

Dep

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U)

Figure 5: Secular trend by least square tech. for the year 1982

288

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1970 1975 1980 1985 1990 1994 Time in year

Ozo

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)

Figure 6: Secular trend by least square method for April The secular trends for both the data sets have manifest that the depletion at Pakistan coastal region has got some value albeit the rate is small. With the help of trend equation we are in the position to predict future status of ozone layer depletion not only for Pakistan but also for other countries of the region. Albeit the from satellite can give near-global covering, but can provide only averaged values of the measured quantity over large regions both in vertical It is rather difficult as well as expensive to properly handle the working of satellite

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instruments because of the variations in the speed and orbit of the satellites. Also, in case of failure of any of the components, necessary repairs take time that influences the accuracy of data. Whereas, the ground based radars can provide data with high vertical resolution by measuring small differences in the time delays of the return pulses above the radar sites. REFERENCES (1) Andrews G D (2000), “An Introduction to Atmospheric Physics”, Cambridge

University Press, London

(2) Johnston, H S (1971), “Reduction of stratospheric ozone by oxide catalyst

supersonic transport”, Science, 173: 517-522

(3) Mészàros E (1995), “Global and Regional Changes in Atmospheric

Composition”, CRC Press Inc., 2000 Corporate Blvd., Florida

(4) Box G E P and Jenkins G M (1976),” Time series analysis, forecasting and

control”, rev. ed. Holden-Day, San Francisco

(5) Bojkov R, Bishop L, Hill W J, and Tiao G C (1990), “A statistical trend

analysis of revised Dobson total ozone data over the northern hemisphere”,

J. Geophs. Res. 95: 9785-9808

(6) Stolarski R S, Bloomfield P, Herman J R, (1991), “Total ozone trends

deduced from Nimbus 7 TOMS data”, Geophys. Res. Lett. 18: 1015-1018

[7]. Gupta S (1999), “Research Methodology and Statistical Techniques”, Deep

& Deep Publications, New Delhi.

[8] Granger C W J, and Newbold P (1986), Forecasting Economic Time Series,

2nd.Edn., Academic Press, New York

[9] Priestley M B(1988), Non-linear and Non-stationary Time series Analysis,

Academic Press, London

[10] Newbold P (1988), Some recent developments in Time Series analysis,

I,II,and III. Inter. Statist. Rev., 56, 17-29

[11 ] M.Ayub Khan Yousuf Zai & Jawaid Quamar (1998), Sing. J. Phys., Vol. 14,

# 1, pp 69-79

(12) M.Ayub Khan Yousuf Zai & Jawaid Quamar (2001), “ Study the

phenomenon of ozone layer depletion as a physical process”, Indian. J.

Phys., 75B (4), 307-314.

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[13] M.Ayub Khan Yousuf Zai, (2004),”A Quantitative Study of effects of Ozone

Layer Depletion on Marine Organisms with reference to coastal regions of

Pakistan,” A Ph.D. thesis.

[14] Anderson T W (1971), The Statistical Analysis of Time Series, Wiley, New

York

[15] Haggan V and Ozaki T (1979), Amplitude-dependent AR model fitting for

non-linear random vibrations, Paper presentation at the International Time

Series meeting, University of Nottingham, UK, March 1979.

[16] Cleveland W S and McGill (1987), Graphical perception: the visual decoding

of quantitative information on graphical displays of data, J. Roy. Stat. Soc.,

A 150, 300

[17] Basu S K, Sinha B K, & Mukherjee S P (2000), Frontiers in Probability and

Statistics, Narosa Publishing House, New Delhi

[18] Subba Rao T (1998), “ Applications of Time Series Ananlysis in Astronomy

and Meteorology”, Chapman & Hall, London

[19] Rowland F S (1991), Ann. Rev. Phys. Chem. 42, 731

[20] Bojkov R D and Fioletov (1995), Geophys., Res. Lett., 22, 2729

[21] Henriksen K and Roldugin V (1995), Geophys., Res., Lett.. 22, 3219

[22] Henriksen K And Larsen H H S (1992), J.Atmos. Terr. Phys., 55, 1113

[23] Herman J R and Larko D (1993), J. Geophys. Res., 98, 12783

[24] Hofmann D J, Oltmans J S, and Harris J M (1994), Geophys. Res. Lett., 21,

1779

[25] Hofmann D J, Oltmans J S, and Koenig G L (1996), Geophys. Res.Lett., 23,

1533

[26] McPeter R D and Hllandsworth (1996), Geophys. Res. Lett., 23, 3699

[27] Rolando R G (1994), J. Geophys. Res. Vol. 99, # D6. 12,937-12,951

[28] Portmann R W, Solomon S, and Rolando R G (1996), J. Geophys. Res.

Vol. 101, # D17, 22,991-23,000

[29] Rolando R G, Frode S, and Jeffery T (1992), J. Geophys. Res. Vol. 97, #

D12, 12967-12,991

[30] Rolando R G (1994), Physics World, April, 1994, 49-55

[31] Tatsuo Shimazaki (1989), Geophysics and Astrophysics Monograph, ed., Terra Scientific. Tokyo

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[32] Attilio B and Sharon B (1997), Encychlopedia of Energy and Environmental,

p 198-1225, Wiley, New York

[33] Solomon S, and Daniel L A (1992), Nature, 357, 33-37

[34] Prather M J, and Watson R T (1990), Nature, 344, 729-734

[35] Kallenrode B M (2004), “ Space Physics”, Springer Verlag, Berlin, New York

[36] Zeilik M (1994), Astronomy, the evolving universe, John Wiley, New York

[37] Richard S L (1990), Dynamics in Atmospheric Physics, Cambridge

University Press, New York [38] Kaler J B (1994), Astronomy, HarperCollins College Publishers, New York

[39] Zirin H (1989), Astrophysics of the Sun, Cambridge University Press,

New York

[40] Unno W & Yuasa M (1992), Astrophys.and Space Sci., 189, 271-278

[41] Seinfeld H J & Pandis N S (1998), Atmospheric Chemistry and physics, from air pollution to climate, JohnWiley, New York

[42] Randel W J & Gille J C (1993), Nature, 365, 533-535

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SPACE RADIATION EFFECTS ON SPACECRAFT

MICROELECTRONICS

Dr. Shazia Maqbool and Ayesha Javed Satellite Research and Development Center (SRDC) Lahore

SUPARCO, Pakistan

Srdclhr@ nexlinx.net.pk

ABSTRACT One of the primary design considerations for a space mission is the survivability of its electronic systems in an ionizing radiation environment. The increasingly complex mission requirements of modern spacecraft for military, commercial and scientific applications have mandated the need for highly capable microelectronics. This trend has been accompanied by the need to provide affordable, lightweight, low volume and low power systems. Both these trends have resulted in the need to adopt commercial microelectronics for space missions as well as to examine emerging technologies. By their very nature, commercial technologies are constantly changing.

The effects of radiations on commercial device technologies have widely been discussed in literature. This paper summarizes these discussions to outline trends in different radiation effects with changing device technologies. A review on radiation response of very large scale integration (VLSI) devices will also be presented. I. INTRODUCTION In the past, rad-hard technology derived from military programmes has dominated the space industry and military applications have had significant influence on the direction and capability of the electronic industry. However, continued reductions in military budgets, coupled with dramatic growth of the consumer electronics industry, have reduced this influence. Market drivers for consumer electronics have taken their products and supporting technologies far beyond the capability of specialized military technology. Consequently, rad-hard technology lags behind the commercial development by about two generations. This situation has led space industry to commercial microelectronics. However, the use of commercial off-the-shelf (COTS) technology brings new issues on the reliability in the space environment.

One of the most significant trends in commercial microelectronics is the move towards smaller dimensions – i.e. “scaling”. Scaling has some benefits for radiation effects resilience: As gate oxide thick-nesses decrease, hole trapping and interface trap build-up are becoming less significant, leading to a trend toward improved total-ionising dose (TID) performance [13, 4]. Similarly, the increasing use of buried epitaxial substrates over the last 20 years [14, 30] has helped decrease single-event latch-up (SEL) sensitivity – both by limiting the charge-collection volume, and by decreasing the substrate series resistance

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[35, 29, 3]. In addition, the concomitant trend towards reduced supply voltage levels suggests that device threshold voltages should soon fall below that required sustaining latch-up. Indeed, if continued scaling forces the industry to adopt silicon-on-insulator (SOI) technology, latch-up should soon be eliminated [13, 30].

However, whilst some radiation effects are becoming less of an issue, new threats have emerged: Another significant trend in COTS technology is the move towards the use of “smart” logic, in device architectures, e.g. advanced memories, complex micro-controllers and field-programmable gate arrays (FPGAs), etc. Here the performance of the logic device requires the inclusion of complex control circuitry internal to the die. Whilst transparent to the user, such circuitry may offer a significant target to ionizing particles and thus be prone to single-event effects (SEEs), such as a single-event upset (SEU) or single-event transient (SET). In such circuitry, these can manifest themselves as single event functional interrupts (SEFIs), whereby the device exhibits an unexpected change in its observable output state [18].

II. SINGLE EVENT EFFECTS (SEE) SEEs are the result of free-charge generation in semiconductor materials caused by a single ionizing particle strike. Different phenomena may arise depending on the location and the instant of the particle strike.

II.I. Single Event Upset (SEU) Single-Event Upset (SEU) is a non-destructive single-event-effect. These are soft errors associated with changes in the state of memory elements – i.e. unexpected bit-flips due to particle strikes. Re-writing the data will restore the memory states.

As technologies moved towards smaller feature sizes and thus had less charge stored on their circuit nodes, it was expected that the critical charge (and thus the linear energy transfer (LET) threshold) for SEU would decrease [1]. Indeed this trend was observed in the 1980’s in the now older generation of devices. However, results on more recent technologies, with minimum feature sizes ranging from 3μm to 0.35μm do not follow this trend; in fact, the threshold LET has remains approximately constant. This levelling off at a minimum LET has been postulated to be the result of manufacturers taking into account the need to maintain a low upset rate from naturally-occurring radioactivity (e.g. alpha particles) or atmospheric neutrons during the design and manufacture of their parts [13, 4]. Recent SEE testing of complementary metal oxide semiconductor (CMOS) technologies (0.15 μm, 0.13 μm, and 90 nm) conforms with these predictions and it is found that the decreased size of the shrinking latches combined with robust design efforts has stabilized the critical neutron cross sections of state of the art static latches. Indeed, the mean time between failure (MTBF) calculated for a million logic gate FPGA fabricated with a 90-nm technology is better than that of the MTBF of a similar complexity array fabricated in 150- or 130-nm processes.

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Figure 1: Relationship between Feature Size and Critical Charge, [31]

II.II. Single Event Transients (SET) This is are also a class of non-destructive soft-error that can cause changes of logical state in combinational logic, or may be propagated in sequential logic through “glitches” on clock or set/ reset lines, etc.

So far, it has been observed that radiation response of logic devices is dominated by errors in registers and memory cells – i.e. SEUs [14]. However, as devices are further scaled down to smaller feature sizes and faster speeds, soft errors in combinational logic, SETs, are expected to become more probable. In contrast to SEUs, which do not show frequency dependence, SETs depend significantly on the operating speed of the devices in question [4, 14]. According to models developed by Shivakumar et al., soft errors in combinational logic are likely to become comparable to SEUs in unprotected memory elements by the year 2011 [38].

II.III. Single Event Latch-Up (SEL) Single Event Latch-Up (SEL) is a potentially destructive single event effect. It can occur due to the presence of parasitic bipolar transistors inherent in CMOS structures, and may lead to an effective short circuit through the device. There are two types of SEL: In traditional or destructive SEL, the device current consumption increases immediately above the maximum specified for the device, causing permanent damage to the device through the burn-out of bond-wires, etc. The other type is known as a micro-latch-up, and during such an event, the device current increases above the normal operating voltage but not above the maximum specified. Micro-latch-up halts device operation and a power reset is required to recover the device. The device may still operate but show signs of permanent damage, such as exhibiting a step-change in its current consumption. Alternatively the damage may not be immediately apparent. Sometimes, a series of micro-latch-up events in quick succession can lead to destructive SEL.

II.IV. Single Event Functional Interrupt (SEFI) One of the most significant trends in COTS technology is the move towards device architectures with in-built “smart logic” – that is for devices which have internal operations transparent to the user. Smart logic requires the inclusion of more control circuitry internal to the die. For example, flash memory devices

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contain a state machine that generates the signals needed to perform read/write operations. Many dynamic random-access memory (DRAM) devices, microprocessors and field-programmable gate-arrays (FPGAs) have a built-in self-test capability, which again increases device complexity. Many DRAMs include redundant memory rows and columns intended to increase device reliability. When the DRAM is powered up, weak or bad rows or columns are replaced with their redundant counterparts and a redundancy-latch has to be used to hold the device configuration. Many synchronous-DRAM (SDRAM) devices also have internal state machines that implement pipelines, programmable refresh modes and various power states. In most of these cases, this control logic is not directly accessible to the user.

Experience from space flight and ground-based ion-beam testing of many COTS devices reveals that this internal control circuitry is susceptible to radiation effects, often manifesting itself as the class of single event effects (SEEs) called single event functional interrupts (SEFIs), whereby an internal upset in this logic causes an unexpected change in the observable state of the device. SEFI was first mentioned in 1996 [5, 18], although SEFI-like signatures had been reported earlier [17, 42, 19]. Early reports were confined to microprocessor SEFIs, however, emerging data handling devices, such as advanced memories and FPGAs, have also been found to be susceptible.

III. MULTIPLE BIT UPSET (MBU) Sometimes, more than one memory cells can be corrupted by the charge deposition originating from the same particle. Such events are characterized as single-event multiple-bit upsets. These errors are mainly associated with memory devices, although any register is a potential target. MBUs, which have been observed during ground-based ion-beam testing and in during space flight, may be attributed to three mechanisms:

• A single particle strike affects more than one bit in one or more words;

• Coincidental, independent SEUs (from different particle strikes) appear as an MBU;

• A single SEFI event causes MBUs (termed as block SEFIs).

The second mechanism is not in fact a true MBU, but is instead an artifact of the diagnostic algorithm and the underlying (usually high) SEU rate. Both SRAMs and DRAMs are prone to MBUs, with DRAMs, generally having a higher probability of getting such errors. MBU rates are expected to increase with the device scaling. However, in some cases, less dense devices have been found to show higher MBU rates than more dense devices [39]. On the other hand, reports of block SEFI events are increasing. Floating gate memories, which do not exhibit traditional MBUs, are susceptible to this class of MBUs.

IV. TOTAL IONISING DOSE

Total ionizing dose in semiconductor devices depend on the creation of electron-hole pairs within dielectric layers and subsequent generation of traps at or near the interface with the semiconductor. This can produce a variety of device effects such as flat-band and threshold voltage shifts, surface leakage currents, and speed degradation of the devices. Many current COTS parts are very susceptible to total dose damage, and may fail at total-dose levels of 5 krad (Si) or even less. Total dose is therefore an issue in space flight where

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long mission lifetimes, and/or exposure to the Van Allen radiation belts means that these dose levels can be easily exceeded.

As commercial devices are scaled to smaller feature sizes, so gate oxide thicknesses are also decreasing. The threshold voltage shift that results from hole traps in gate oxides decreases as the square of oxide thickness, assuming that the hole trapping efficiency is unchanged as the oxide thickness is reduced [23]. It has been shown that hole trapping will reduce further because of tunneling as oxides are scaled below 10nm [34]. Thus, for the highly scaled devices, hole trapping and interface traps are not likely to remain major concerns for devices operating in a radiation environment. However, it should be noted that even in highly scaled devices there would be isolation dielectrics, which are still relatively thick. Thus this is isolation/field oxide that dominates total dose response of commercial devices [39, 13, 4,].

V. TRENDS IN DEVICES

This section presents a review of radiation issues in SOTA and emerging microelectronics.

V.I. MEMORIES Space radiation effects on different types of memory devices are discussed below.

V.I.I. DRAMs

DRAM technology has grown rapidly in recent years. The first DRAM, introduced in the early 1970s, contained only 1,024 bits, but modern DRAMs are available containing 256 megabits or more. Large DRAMs incorporate a controller to provide parallelism in operations and hence an increased memory throughput. Their high density and superior performance characteristics make them an attractive candidate for on-board data recording to fulfill increasingly higher mission data storage requirements. In addition, recent technology has permitted the stacking of dies into single units providing even denser packaging of DRAMs into a single device. However, the use of DRAMs for space applications does not come without certain penalties. DRAMs have historically been considered as devices very sensitive to SEUs, since the circuit errors were observed on these components back in the seventies. Their high sensitivity to ionising particle strikes comes from their characteristic of passively storing bit information as charge stored in a circuit node. Although the amount of charge stored decreases steadily from one technology generation to the next, unexpectedly, the error rate has been found to decrease or stay constant [24, 7, 14]. However, the observation of non-traditional SEEs, e.g. SEFIs, raises new concerns over the reliability of these devices in radiation environment. Both the Cassini and Hubble Space Telescope (HST) missions have used solid state data recorders (SSDRs) made from DRAM [21]. Observed SEE results include the standard single bit upset (SEU) errors, stuck bits, MBUs, and column or row errors (where a single ion strike induces a partial or full address column or row to be in error in a single device) [21, 39]. Label termed column and row errors as block SEFIs [20]. Ground-based ion-beam testing of DRAMs has also shown standard

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SEFIs (e.g with the device entering test or standby modes) in addition to above-mentioned errors [20, 18].

It should be noted that advanced DRAM architectures are also emerging. An example of an advanced DRAM is Synchronous DRAM (SDRAM) that can provide even more storage capacity on a chip along with an increase in access speed. These devices have underlying characteristics of stuck bits and MBUs. Increased level of complexity in these devices leads to higher susceptibility of SEFIs [33].

V.I.II. SRAMs

These devices are susceptible to SEUs, generally with quite low thresholds (often below 1 MeVcm2/mg) [2]. They are also subject to MBUs. However, their MBU rates are significantly smaller than their SEU rates. There is no evidence from in-orbit observations that the denser devices are necessarily more prone to MBUs than the older devices [39, 41] although ground based tests suggest this. Stuck bits are sometimes observed, but only during irradiation with particles of high LET (i.e. heavy-ions) [7]. Newer generations of SRAMs, using a 6T cell design, are expected to have an improved SEU and total dose response [22, 32, 7].

V.I.III. Flash Memories

Flash memory technology comes with advantages in terms of density and non-volatility. It provides fast read access, comparable to that of DRAMs. However, erasing and writing new data in flash memories is a more complex operation, requiring application of high voltage. Newer flash devices use complex internal architectures to improve write and erase times, as well as to make device operation more transparent to user.

There are two types of flash architecture: NOR and NAND. Whilst both architectures have the same basic storage element, it is the interconnection of these memory cells that distinguishes structure. In the NOR flash memory array, the bit line logic goes to “0” if any of the memory cell transistors is on. In the NAND flash memory array, all memory cell transistors are required to be on for bit line to go to “0” state. The NAND architecture is more sensitive to radiation [25].

Radiation testing has been performed on Intel, Samsung, Toshiba, AeroFlex, and SanDisk Flash memory devices [36, 28, 27]. The observed SEEs are dominated by errors in their complex internal architectures rather than in the non-volatile storage elements. Test results have shown that flash devices are immune to SEUs when powered off. The probability of getting an upset is particularly high during write mode. Static and dynamic read modes have also demonstrated complex control-related upsets, where the functional consequences of these errors can be multiple. Sometimes, a steep increase in the current consumption is observed during or after irradiation.

V.I.IV. EEPROMs

Electrically Erasable Programmable Read-Only Memory (EEPROM) provides non-volatile storage like Flash memories. The principal difference between the two technologies is that an EEPROM requires data to be written or erased one

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byte at a time whereas flash memory allows data to be written or erased in blocks. This makes flash memory faster. Radiation test results on EEPROMs are presented in [18, 20]. Similar to flash memories, the devices are found to be more susceptible during write mode. SEFI has been observed in these memories as well.

V.I.V. Mitigations for Memory Devices

There are three approaches to improve survivability of microelectronics in space environment.

• Firstly, to invent better semiconductor process to make the memory cell less susceptible to direct radiation. Researchers found that performance under radiation can be improved by repositioning various component junctions or by using silicon-on-sapphire (SOS) or SOI technologies. All these methods require redesign of the memory chips and call for new process technologies that are not widely used for memory chips and therefore, present a risk in production cost and in scalability when memory technology changes.

• The other way is to use COTS memory parts. It has been found that every memory chip exhibits slightly different characteristic under radiation environment. Even the same batch of chips can react quite differently among each other. Some chip works well in the energy environment while others fail miserably. Therefore, the most suitable way is to test-and-select. NASA decided to use COTS parts even in the International Space Station. This is obviously for cost reason and to allow upgrade path as memory technology advances during their course [43].

• Implementation of EDAC (Error Detection and Correction Codes) techniques in both hardware and software can prove helpful in fighting against the hazardous effects of radiations.

V.II. MICROPROCESSORS The most complex type of digital logic device used in on-board is the microprocessor. Using commercial processors for space missions brings potential advantages in terms of cost and design time reduction. These devices are accompanied by COTS software applications, development tools, and operating systems. Processors such as the 80Cx86 family and the Power PC are being flown in space despite being susceptible to ionizing radiation. These processors are not radiation hardened and have been found to be susceptible to SEUs.

Microprocessors work by continuously moving data between registers; the memory unit with arithmetic and logic unit operations and flag registers updates etc. It is unlikely that all sections will be in use during the processing of a program. The application software, which is being executed, determines how many sections are being used at any given time. Moreover, each section might have a different sensitivity to SEU. Therefore, the SEU-induced effects in microprocessors are strongly application dependent. Many commercial processors have been tested to evaluate their suitability for space applications. These include the 80x86 architectures, SPARC, Motorla 68020, Pentium, Alpha, and PowerPC’s [6, 26, 20, 11, 37, 12]. All devices experienced some type of SEFI or device lockups at fairly low threshold LETs and authors have suggested that reliable operation in the radiation environment will require at least a detection and reset capability.

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One result, which was certainly unexpected, is that the threshold LET has essentially not changed during last many years [13]. Table1 compares threshold LET of different microprocessors.

Mitigation:

Implementation of either offline or online fault detection techniques like watchdog timers, Locksteps and built in testing in microprocessors can help against the radiation caused damages.

Device Manufacturer Feature Size (approx)

Threshold LET (MeV-cm2/mg)

Z-80 Zilog 3μm 1.5-2.5

8086 Intel 1.5μm 1.5-2.5

80386 Intel 0.8μm 2-3

68020 Motorola 0.8μm 1.5-2.5

LS64811 LSI 1.2μm 2-2.5

90C601 MHS 1.2μm 2-2.5

80386 Intel 0.6μm 2-3

PC603e Motorola 0.4μm 1.7-3

Pentium Intel 0.35μm 2-3

Power PC750 Motorola 0.25μm 2-2.5

PowerPC7455 Motorola 0.18μm 1

Table1: Upset Threshold of Microprocessors [13]

V.III. FIELD PROGRAMMABLE GATE ARRAYS (FPGAs) This technology offers number of advantages including a highly compact solution, high integrity, flexibility, reduced cost, faster and cheaper prototyping, and reduced lead-time before flight. The capacity and performance of FPGAs suitable for space flight have been increasing steadily for more than a decade. The application of FPGAs has moved from simple glue logic to complete platforms that combine several real-time system functions on a single chip [9].

The choice of type of storage for the configuration drives the radiation performance of the device [15]. FPGAs can be split into two categories: namely re-programmable and one time programmable (OTP). Reprogrammable technology offers volatile SRAM or non-volatile EEPROM/Flash cells to hold the device configuration. SRAM-based technology has been evolving at a faster pace than OTP technology, and now features a million system gates or more on a single chip, and hence has become an attractive choice for high performance applications. However, one must be aware not only of radiation

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issues, but also of concerns such as the total loss of configuration from single ion hit. OTP technology on the other hand offers radiation performance comparable to application specific integrated circuit (ASICs). The most commonly used OTP FPGAs use antifuses for storing its configuration, either using oxide-nitride-oxide (ONO) or metal-to-metal (M2M) antifuse structures [16].

FPGAs are available at different reliability levels, ranging from inexpensive COTS devices to high reliability, rad-hard devices, as well as different device speeds, capabilities, and configurations. Both Actel and Xilinx have been offering radiation tolerant devices for space applications. The Actel OTP devices have been the primary FPGA technology used in space flight systems to date. Actel’s ACT1, ACT2 and ACT3 have been very popular among space designers [15]. Commercial SX and SX-A series have also been reported as being capable of tolerating total doses as high as 100 krads(Si) or more. These devices are latch-up immune as well. The flip-flop element of the basic device is considered as being radiation “tolerant”; enhanced radiation hardened levels can be achieved via incorporation of software or hardware implemented mitigation strategies [16]. Although ONO antifuses are susceptible to SEGR, the threshold is found to be quite high [15]. The probability of an SEGR event is low and one rupture does not cause permanent damage to the device. Typically it would take at least 10 ruptures to cause a failure. Actel introduced products using a M2M antifuse. It is reported that this antifuse technology is immune to SEGR effect to a currently tested LET threshold of 80 MeV-cm2/mg.

Actel Corporation offers two classes of rad-hard FPGAs, RH1020 and RH1280 with equivalent gate densities of 2,000 and 8,000 respectively. These products are latchup immune and can withstand total dose in excess of 300 krads (Si). Its SEU performance is predicted to be 10-6 upsets per bit-day in a 90% worst-case geosynchronous earth orbit. Actel proposes mitigation techniques to improve SEU performance of these devices by incorporating TMR or by avoiding flip-flops in the sequential units.Adaptation of one of these techniques is recommended for critical design sections.

Another rad-hard FPGA RHAX250-S device technology offers a gate count of 250, 000 with even better radiation performance. In addition to these rad-hard products, Actel offers radiation tolerant devices such as RTAX_S. This device technology has TID response comparable to RH1020 and RH1280 devices, and latchup and SEU immunity to 104 and 60 MeV-cm2/mg respectively.

Xilinx offers the XQR series for space applications. This series is a subset of their commercial XC40000XL family. Although these devices have demonstrated acceptable total dose and latch-up performance for many space applications, they are susceptible to single event effects including SEFIs [8, 9]. Work is in progress at Xilinx for the development of the single event immune reconfigurable FPGA (SIRF).

SEUs in reprogrammable FPGAs can be grouped into three categories [9]:

Configuration upsets are defined as the upsets in the configuration memory of the device and can be detected by read-back. The likelihood of failure will

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depend upon the upset location and the specific design utilisation of the device resources. A configuration upset can sometimes lead to high current states. For example, a SEU may cause two output drivers to be connected together.

User logic upsets represent upsets in the circuit elements that are not directly accessible by read-back. The effect of these is dependent upon the particular logical design implemented by the user.

System upsets are those upsets that occur in the control circuitry of the FPGA. As an example, it is possible for a single upset in the configuration control circuitry to change many configuration bits simultaneously .This kind of anomaly can only be detected by noting the malfunction of the device.

V.IV. GaAs DEVICES GaAs devices are used in high speed digital and microwave applications. Since no dielectric layers are used in GaAs devices, they exhibit extreme radiation tolerance - up to several hundred Mrad (GaAs) (two orders of magnitude higher than for equivalent Si-based technologies) [44].

In general GaAs technology is very susceptible to SEU but hardening with low temperature buffer layers offers orders of magnitude improvement.

V.V. OPTO-ELECTRONIC DEVICES Broadly opto-electronic devices include light emitting diodes (LEDs), laser diodes, optical detectors, and optical couplers. These products are also not considered radiation hard without special processing. For example opto couplers can be sensitive to degradation of current transfer ratio (CTR) at a dose of 2-3 krad (Si). Some types of opto-emitters are severely degraded by the proton bombardment at a TID of 1-2 krads. Displacement damage dose (DDD) is most pronounced in optocouplers and lasers. High bandwidth optocouplers are extremely sensitive to SEUs. Permanent damage can be caused by displacement damage, for example loss in LED power (though devices with a hardened LED will ultimately suffer from photo-response degradation) [45] and from ionizing damage in the photo detector. Optocouplers can be of linear or digital type and many different designs exist, each with a different radiation response. Optocoupler failures occurred on the Topex-Poseidon mission [45] at TID levels of 20-30 krad (Si). For systems that use lens coupling, radiation darkening of the lens, due to TID, can sometimes be a problem (particularly for graded index, GRIN, lenses).

VI. CONCLUSIONS Adoption of COTS devices and standards has become a prevailing practice for space applications. Continuously changing COTS technologies impose a threat to their reliable use in space radiation environment.

A general trend towards an improved TID and SEL response has been observed. SEFIs and SETs are recognized as two potentially dominating radiation hazards from current knowledge of device technology and its radiation performance. SETs are predicted to be of serious concern in near

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future. SEFIs, on the other hand, have been reported with present technology and likely to get worse as device technology moves towards smarter and more transparent architectures.

Over the past many years, COTS technology has been flown in space systems with a reasonable expectation of success. This has primarily been achieved by a thorough understanding of radiation response of these devices and then, application of appropriate mitigation techniques and sound engineering practices.

VII. ACKNOWLEDGMENT This work is attributed to the unmatched guidance of Dr. Riaz M Suddle and to SUPARCO for sponsoring it.

VIII. REFERENCES [1] Akers, L.D., “Microprocessor Technology and Single Event

Suscptibility”, Proc. 10th Annual AIAA/USU Conference on Small Satellites, Logan, Utah, 1996

[2] J.R.Coss et al., “Device SEE Susceptibility Update: 1996-1998”, IEEE NSREC Data Workshop Record, pp. 60-81, July, 1999

[3] P.E. Dodd, M.R Shaneyfelt, E. Fuller, J.C Pickel, F.W. Sextan and P.S. Winokur “Impact of Substrate thickness on Single-Event Effects in Integrated Circuits”, IEEE Trans. Nucl. Sci., Volume-48, Issue-6, pp. 1865-1871, December, 2001

[4] Paul V. Dressendorfer “Basic Mechanisms for the New Millennium”, IEEE NSREC Short Course, July, 1998

[5] EIA/JEDEC Standard, “Test Procedures for the Measurement of Single Event Effects in Semiconductor Devices from Heavy Ion Irradiation”, Electronic Industries Association, Engineering Department, Arlington, 1996

[6] Estreme, F. et al., “SEU and Latchup Results for SPARC Processors”, IEEE Radiation Effects Data Workshop Record, pp. 13-19, July, 1993

[7] Faccio, F., “COTS for the LHC Radiation Environment: The Rules of the game”, 6th Workshop on Electronics for LHC Experiments, Krakow, Poland, 2000

[8] Fuller, E. et al., “Radiation Characterization, and SEU Mitigation, of the Virtex FPGA for Space-Based Reconfigurable Computing”, Presented at IEEE NSREC Conference, October, 2000

http://klabs.org/richcontent/Papers/Xilinx/Xilinx_NSREC2000.pdf accessed on 5th March 2004

[9] Gaisler, J., “Suitability of Reprogrammable FPGAs in Space Applications”, ESA Technical Report, 2002

http://www.estec.esa.nl/microelectronics/asic/fpga_002_01-0-4.pdf accessed on 5th March 2004

[10] Hodgart, M.S. and Tiggeler, H., “Introduction to error Correcting Codes in Satellite Applications”, Technical Report, Surrey Space Centre, 1999

[11] Howard, J.W. et al., “Total Dose and Single Event Effects Testing of the Intel Pentium III (P3) and AMD K7 Microprocessors”, IEEE Radiation Effects Data Workshop Record, pp. 38-47, July, 2001

Page 23: SOLAR ACTIVITY AND OZONE LAYER DEPLETION · 2011-02-06 · solar activity and ozone layer depletion comparision of parametric evaluation of total ozone mapping spectrophotometer (toms)

[12] Irom, F. et al., “Single-Event Upset in Commercial Silicon-On-Insulator PowerPC Microprocessors”, IEEE Trans. on Nucl. Sci., Vol. 49, Issue-6, pp. 3148-3155, December, 2002

[13] A.H. Johnston, “Radiation Effects in Advanced Microelectronis Technologies”, IEEE Trans. Nucl. Sci., Volume-45 , Issue-3 , pp. 1339-1354, June, 1998

[14] Johnston, A.H., “Scaling and Technology Issues for Soft Error Rates”, 4th Annual Research Conference on Reliability, Stanford University, October, 2000

http://nepp.nasa.gov/docuploads/40D7D6C9-D5AA-40FC-829DC2F6A71B02E9/Scal-00.pdf accessed on 5th March 2004

[15] Katz, et al., “Radiation effects on Current Field Programmable Technologies”, Presented at IEEE NSREC Conference, July, 1997

http://klabs.org/richcontent/Papers/nsrec97fpgapaper.PDF accessed on 5th March 2004

[16] Katz, R. et al., “Logic design Pathology and Space Flight Electronics”, MAPLD International Conference Proceedings, 1999

http://klabs.org/richcontent/Papers/Mapld99/A4_Katz_P.pdf accessed on 5th March 2004

[17] Koga, R. et al., “Techniques of Microprocessor Testing and SEU rate Prediction”, IEEE Trans. on Nucl. Sci., Vol.-32, Issue- 6, pp. 4219-4224, December, 1985

[18] Koga, R. et al., “Single Event Functional Interrupt (SEFI) Sensitivity in Microcircuits”, Proc. 4th European Conference on Radiation and its Effects on Components and Systems (RADECS), pp. 311-318, 1997

[19] Label, K. et al., “SEU Tests of 80386 Based Flight-Computer/Data Handling System and of Discrete PROM and EEPROM Devices and SEL tests of Discrete 80386, 80387,PROM, EEPROM, and ASICs”, IEEE Radiation Effects Data Workshop Record, pp. 1-11, 1992

[20] Label, K. et al., “Radiation Effect Characterizationand Test Methods of Single Chip and Multi Chip Stacked 16Mbit DRAMs”, IEEE Trans. on Nucl. Sci. Vol 43, Issue-6, pp. 2974- 2981, December, 1996

[21] Label, K., “Single Event Effect Test Results for Candidate Spacecraft Eectronics”, IEEE Radiation Effects Data Workshop, pp. 14-21, July, 1997

[21] Label, K. et al., “Anatomy of an In-Flight Anomaly: Investigation of Proton-Induced SEE Test Results for the Stacked IBM DRAMs”, IEEE Trans. on Nucl. Sci., Vol 45, Issue-6, pp. 2898-2903, December, 1998

[22] A.J.Lelis et al., “Radiation Response of Advanced Commercial SRAMs”, IEEE Trans. Nucl. Science, Vol.43, Issue-6, pp. 3103-3108, December, 1996

[23] T.P. Ma and P.V. Dressendorfer, “Ionizing radiation effects in MOS devices and circuits”, Wiley Inter-science, New York, 1989

[24] Massengill, L.W, “Cosmic and Terrestrial Single Event Radiation Effects in Dynamic Random Access Memories”, IEEE Trans. on Nucl. Sci, Vol. 42, Issue-2, pp. 576-593, April, 1996

[25] Miyahira, T. and Swift, G., “Evaluation of Radiation Effect in Flash Memories”, JPL Publication, 2003

[26] Moran, A. et al., “Single Event Effect testing of the Intel 80386 Family and the 80486 Microprocessor”, Proc.3rd European Conference on Radiation and its Effects on Components and Systems (RADECS), pp. 263-269, September, 1995

[27] Nguyen, D.N and Scheick, L.Z., “SEE and TID of Emerging Non-Volatile Memories”, JPL Publication, 2002

Page 24: SOLAR ACTIVITY AND OZONE LAYER DEPLETION · 2011-02-06 · solar activity and ozone layer depletion comparision of parametric evaluation of total ozone mapping spectrophotometer (toms)

[28] Nguyen, D.N. et al., “Radiation Effects on Advanced Flash Memories”, IEEE Trans. on Nucl. Sci., Vol 46, Issue-6, pp. 1744 – 1750, December, 1999

[29] A. Ochoa, Jr., and P.V. Dressendorfer, “A Discussion of the Role Distributed Effects in Latchup,” IEEE Trans. Nucl. Sci., vol. NS-28, pp. 4292–4294, Dec. 1981

[30] Oldham, T.R., “How device scaling affects single event effects sensitivity”, IEEE NSREC Short Course, July, 2003

[31] Petersen, E.L et al., “Calculations of Cosmic Rays Induced Soft Upset and Scaling in VLSI Devices”, IEEE Trans. Nucl. Sci., Vol-29, Issue-6, pp. 2055-2063, December, 1982

[32] C.Poivey et al., “Radiation Characterisation of Commercially Available 1Mbit/4Mbit SRAMs for Space Applications”, NSREC Data Workshop, 1998

[33] Rodgers, J et al., “Advanced Memories for Space Applications”, IEEE Microelectronics Reliability & Qualification Workshop, December, 2001

http://parts.jpl.nasa.gov/mrqw/mrqw_presentations/S1_rodgers.pdf accessed on 5th March 2004

[34] N.S. Saks, M.G. Ancona and J.A. Modola, “Radiation Effects in MOS Capacitors with Very Thin Oxides at 80K”, IEEE Trans. Nucl. Sci., Vol. 31, pp. 1249, 1984

[35] J.E. Schroeder, A. Ochoa, Jr., and P.V. Dressendorfer, “Latchup elimination in bulk CMOS LSI circuits,” IEEE Trans. Nucl. Sci., Vol-27, pp. 1735–1738, December, 1980

[36] Schwartz, H.R. et al., “Single Event Upset in Flash Memories”, IEEE Trans. on Nucl.Sci., Vol-44, Issue-6, pp 2315-2324, December, 1997

[37] Seifert, N. et al., “Impact of Scaling on Soft-Error Rates in Commercial Microprocessors”, IEEE Tans. on Nucl. Sci., Vol. 49, Issue-6, pp. 3100-3106, December, 2002

[38] Shivakumar, P. et. al, “Modeling the Effect of Technology Trends on Soft Error Rate of Combinational Logic”, Proc. International Conference on Dependable Systems and Networks (DSN), pp. 389-398, June, 2002

[39] Swift, G.M., and Guertin, S.M., “In-flight Observations of Multiple Bit Upset in DRAMs”, IEEE Trans. on Nucl. Sci., Vol. 47, Issue-6, pp. 2386-2391, December, 2001

[40] Underwood, C.I., “Single Event Effects in Commercial Memory Devices in the Space Radiation Environment”, PhD Thesis, University of Surrey, 1996

[41] Underwood, C.I., “Observations on the reliability of COTS-device-based SSDRs operating in low earth orbit”, Fifth European conference on Radiation and its Effects on Components and Systems (RADECS), pp. 387-393, September, 1999

[42] Velazco, R. et al., “SEU Testing 32-bit Microprocessors”, IEEE Radiation Effects Data Workshop Record, pp. 16-20, July, 1992

[43] Products guide www.Simmtester.com. Radiation hardened memory devices

[44] C Claeys and E Simoen, Literature study on radiation effects in advanced semiconductor devices, ESTEC contract report P35284-IM-RP-0013, March 30 2000

[45] A H Johnston and B G Rax, "Proton damage in linear and digital optocouplers," IEEE Trans Nucl Sci, vol 47, pp 675 -681, 2000.

[46] http://klabs.org/richcontent/MAPLDCon98/Papers/c4_miyahira.pdf accessed on 5th March 2004

[47] accessed on 5th March, 2004http://parts.jpl.nasa.gov/docs/PID16621.pdf