Linear Energy Transfer Effects Research Articles

OSLD nanoDot characterization for carbon radiotherapy dosimetry

Objective. This study characterized optically-stimulated luminescent dosimeter (OSLD) nanoDots for use in a therapeutic carbon beam using the Imaging and Radiation Oncology Core (IROC) framework for remote output verification. Approach. The absorbed dose correction factors for OSLD (fading, linearity, beam quality, angularity, and depletion), as defined by AAPM TG 191, were characterized for carbon beams. For the various correction factors, the effect of linear energy transfer (LET) was examined by characterizing in both a low and high LET setting. Main results. Fading was not statistically different between reference photons and carbon, nor between low and high LET beams; thus, the standard IROC-defined exponential function could be used to characterize fading. Dose linearity was characterized with a linear fit; while low and high LET carbon linearity was different, these differences were small and could be rolled into the uncertainty budget if using a single linearity correction. A linear fit between beam quality and dose-averaged LET was determined. The OSLD response at various angles of incidence was not statistically different, thus a correction factor need not be applied. There was a difference in depletion between low and high LET irradiations in a primary carbon beam, but this difference was small over the standard five readings. The largest uncertainty associated with the use of OSLDs in carbon was because of the k Q correction factor, with an uncertainty of 6.0%. The overall uncertainty budget was 6.3% for standard irradiation conditions. Significance. OSLD nanoDot response was characterized in a therapeutic carbon beam. The uncertainty was larger than for traditional photon applications. These findings enable the use of OSLDs for carbon absorbed dose measurements, but with less accuracy than conventional OSLD audit programs.

Impact of high LET radiation on various properties of CR-39 detector

Since polyallyl diglycol carbonate (PADC), viz. CR-39 has been widely used for radiation detection and measurement in various complex radiation fields, therefore, a systematic study has been carried out in this work to demonstrate the significant effect of linear energy transfer (LET) of heavy ions on the optical, structural and chemical (etching) properties of the detector. The PADC samples were exposed to heavy ions (7Li, 12C, 16O and 19F) of different energies to study the effect of LET from 76 to 1002 keV/μm. Samples were chemically processed to develop the latent tracks induced by heavy ions. Image analysis showed an increase in the damaged track size with the LET as well as the etching time. Having same energy, the track sizes of two different ions were found to be different because of the differences in their LET values. Similarly, for one particular ion, the track sizes were found to be smaller for higher energy due to low LET than that of the lower energy corresponding to high LET. Hence, this criterion is successfully demonstrated for particle identification by using PADC. Furthermore, spectrophotometric studies (UV–vis, FTIR) have been carried out to determine the changes in opacity, Urbach's energy, optical bandgap, molecular vibrations and red shift of the cut off wavelength with the increase in LET values.

Study of Linear Energy Transfer Effect on Rib Fracture in Breast Patients Receiving Pencil-Beam-Scanning Proton Therapy

<h3>Purpose/Objective(s)</h3> To study the linear energy transfer (LET) effect upon rib fracture (RF) in breast cancer patients treated with pencil-beam scanning proton therapy (PBS) using dose-linear energy transfer volume histogram (DLVH). <h3>Materials/Methods</h3> After IRB approval, we retrospectively identified RF cases detected after workup of chest wall pain or incidentally on imaging in breast cancer patients treated with PBS to the breast/chest wall and regional nodes from 2015-2020. Control patients were selected to match the RF patients 2:1 considering prescription dose, boost location, reconstruction status, laterality, chest wall thickness, and treatment year. For all plans, a chest wall was contoured, incorporating ribs and intercostal muscles within the 50% prescription isodose line. Both dose and LET were calculated using a planning tool dose engine. DLVH was generated for each patient, using dose and LET as the two axes. The DLVH index, <i>V</i>(<i>d, l</i>), defined as <i>V</i>(% for normalized volume or cc for absolute volume) of the structure with a dose of at least <i>d</i> Gy[RBE] and an LET of at least <i>l</i> keV/µm, was calculated for all combinations of <i>d</i> and <i>l</i>. Conditional logistic regression model was used to establish the relation of <i>V</i>(<i>d, l</i>) and the observed RF at each combination of <i>d</i> and <i>l</i>. The derived <i>p values</i> constitute a <i>p value</i> map in the 2D dose and LET plane. Concordance and its standard error (se) maps were generated to evaluate the performances for all DLVH indices. A correlation coefficient map was obtained to determine the correlation between the featured DLVH indices. <h3>Results</h3> Eight RF cases were identified, and 16 controls were matched. Of RF patients, seven were treated with post-mastectomy (PMRT) and one was treated with post-lumpectomy radiotherapy. Six RF patients treated with PMRT received a dose of 50 Gy[RBE] in 25 fractions to the chest wall and regional lymph nodes; of these, four received a simultaneous integrated boost (SIB) of 56.25 Gy[RBE] to the chest wall (n=2) or axillary nodes (n=2), and one received a sequential boost of 14 Gy[RBE] in 7 fractions to the chest wall. One RF patient that received PMRT was treated with 40.05 Gy[RBE] in fifteen fractions to the chest wall and regional lymphatics. The post-lumpectomy patient received 50 Gy[RBE] in 25 fractions to the whole breast and regional nodes with a SIB of 56.25 Gy[RBE] to the lumpectomy cavity. Two characteristics correlated with RF (<i>p</i><0.2): 1) Smaller <i>V</i>(50-54 Gy[RBE], 0-4.4keV/µm) of the RF patients with a maximum concordance of 0.813 (se 0.114); 2) Larger <i>V</i>(0-36 Gy[RBE], 5.2-6.8keV/µm) of the RF patients with a maximum concordance of 0.875 (se 0.119) compared with controls. These two features were independent from each other with a weak negative correlation (-0.185). <h3>Conclusion</h3> The increase of high LET in moderate dose regions of the chest wall from constraining the adjacent heart and lung dose during PBS treatment planning may result in increased risk of RF.

The effect of linear energy transfer on the early, transient radiolytic oxygen depletion in the radiolysis of water by high-dose-rate irradiating protons

Monte Carlo multi-track chemistry simulations were carried out to study, from a radiation chemistry perspective, the effect of “linear energy transfer” (LET) on the transient yields and concentrations of radiolytic oxygen consumption in the high-dose-rate (∼107 Gy/s) radiolysis of both pure air-saturated (0.25 mmol/L O2) and oxygenated (30 µmol/L O2) cell water, in the interval ∼1 ps–10 µs. Our simulation model consisted of randomly irradiating water with single pulses of 5 MeV (LET ∼ 8 keV/µm), 1.5 MeV (LET ∼ 19.5 keV/µm), and 0.7 MeV (LET ∼ 33 keV/µm) protons at 25 °C. Similar to what is observed with low-LET irradiation (∼300 MeV protons, LET ∼ 0.3 keV/µm), our calculations showed that, in pure, aerated water, the concentration of depleted oxygen, [−O2], exhibits a pronounced maximum around ∼0.1–0.2 µs for all three high-LET irradiating protons studied. This maximum increased markedly with increasing LET. As expected, the effect of adding competing scavengers of both hydrated electrons and•OH radicals on the radiolytic O2depletion in oxygenated cell water (a more bio-mimetic model of cells) irradiated by 5 MeV protons delivered at the same dose rate led to a marked decrease in the maximum of [−O2] around 1 µs. However, contrary to what is observed for low-LET irradiation, we found that the transient O2consumption is quite substantial under high-LET irradiation conditions. This is explained by the fact that, even though their underlying mechanism of action differs, high-LET particles affect radiolysis yields in a similar way to high dose rates.

Single-event-transient effect in nanotube tunnel field-effect transistor with bias-induced electron–hole bilayer

The single event transient (SET) effect in nanotube tunneling field-effect transistor with bias-induced electron–hole bilayer (EHBNT-TFET) is investigated by 3-D TCAD simulation for the first time. The effects of linear energy transfer (LET), characteristic radius, strike angle, electrode bias and hit location on SET response are evaluated in detail. The simulation results show that the peak value of transient drain current is up to 0.08 mA for heavy ion irradiation with characteristic radius of 50 nm and LET of 10 MeV⋅cm2/mg, which is much higher than the on-state current of EHBNT-TFET. The SET response of EHBNT-TFET presents an obvious dependence on LET, strike angle, drain bias and hit location. As LET increases from 2 MeV⋅cm2/mg to 10 MeV⋅cm2/mg, the peak drain current increases monotonically from 0.015 mA to 0.08 mA. The strike angle has an greater impact on peak drain current especially for the smaller characteristic radius. The peak drain current and collected charge increase by 0.014 mA and 0.06 fC, respectively, as the drain bias increases from 0.1 V to 0.9 V. Whether from the horizontal or the vertical direction, the most sensitive hit location is related to w t. The underlying physical mechanism is explored and discussed.

Characterization of the Total Charge and Time Duration for Single-Event Transient Voltage Pulses in a 65-nm CMOS Technology

This article presents the circuits and heavy-ion irradiation test results of a single-event transient (SET) measurement chip in a 65-nm complementary metal–oxide–semiconductor (CMOS) technology. The measurements contain two parts: total SET ionization charge and SET pulse duration. Transistors with different types and dimensions were implemented as victim devices to evaluate how transistor parameters impact the SET effects. Additionally, SET variation from different supply voltages was also investigated. The test chip has been tested under a heavy-ion beam with an effective linear energy transfer (LET) from 20.4 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$88.35~\text {MeV}\cdot \text {cm}^{2}$ </tex-math></inline-formula> /mg using a 0°–45° incidence angle.

Single-event effect testing of the PNI RM3100 magnetometer for space applications

Abstract. The results of a destructive single-event effect susceptibility radiation test of the PNI RM3100 magnetometer sensor, specifically the MagI2C ASIC (application-specific integrated circuit) on the sensor board are presented. The sensor is a low-resource commercial off-the-shelf (COTS) magneto-inductive magnetometer. The device was monitored for destructive events and functional interruptions during exposure to a heavy ion beam at the Lawrence Berkeley National Laboratory's 88′′ Cyclotron. The RM3100 did not experience any destructive single-event effects when irradiated to a total fluence of 1.4 × 107 cm−2 at an effective linear energy transfer (LET) of 76.7 MeV cm2 mg−1 while operated at nominal voltage (3.3 V) and elevated temperature (85 ∘C). When these results are combined with previous total ionizing dose tests showing no failures up to 150 kRad (Si), we conclude that the PNI RM3100 is extremely radiation tolerant and can be used in a variety of space environments.

Effect of linear energy transfer on the scintillation properties of Ce-doped Ca3B2O6 crystals

The effect of linear energy transfer (LET) on the scintillation properties of Ce-doped Ca3B2O6 crystals was analyzed. The rise in the scintillation temporal profile was significantly slower for 20 MeV H+ irradiation, which had the lowest LET among the experimental conditions considered in this study. Observations of the scintillation temporal profiles at different wavelengths revealed that a fast component in the ultraviolet (UV) region, which is attributed to localized centers such as defects, contributes to the shoulder structure at the rise. The relative contribution of the fast and Ce3+ emission components depends on the LET, which results in LET-dependent scintillation temporal profiles. The LET effect on the relative contribution of the two components is explained in terms of the competition between the energy transfer from the host to Ce3+ ions or the localized centers, and the quenching owing to the interaction between excited states prior to the energy transfer.

Outstanding Conference Paper Award: 2019 IEEE Nuclear and Space Radiation Effects Conference

In this work, experimental results are presented on single-bit-upsets (SBU) and multiple-bit-upsets (MBU) on a 45 nm SOI SRAM. The upset cross-sections were obtained with accelerated testing using both protons and heavy ions. The proton upset cross-sections were obtained using proton energies ranging from 1 to 500 MeV and the heavy ion data were obtained using ions with effective linear energy transfer (LET) values from 0.6 to 100 . Overall, the SBU data on the 45 nm SOI SRAM showed upset cross-sections-per-bit that were very similar to the cross-sections-per-bit on a 65 nm SOI SRAM for both heavy ion and proton testing. This result continues a trend that has been observed with advanced SOI CMOS SRAMs. In contrast to the SBU data, the MBU data on the 45 nm SRAM showed significantly higher upset cross-sections relative to the 65 nm SRAM. The higher MBU cross-sections were also expected based upon the closer spacing of the nodes in adjacent cells. While the overall trends were anticipated, the major focus of the paper was to understand a diverse range of single event effects that were contributing to the measured upsets. As a function of the incident proton energy, both scattering events and direct ionization upsets were observed. The data also highlighted the unique upset results that are produced at a 90 degree tilt angle. The MBU data showed a very large dependence on the data stored in the SRAM. The data dependence was understood based upon the layout of the SRAM cells and the MBU upsets produced by strikes in common diffusion regions. A detailed analysis of the MBU data showed that almost all of the MBU events occurred in adjacent cells along the bit-lines of the array. This result is very important since the MBU events along the same bit-line will be effectively corrected by error-correctingcode (ECC) circuits. Thus, the higher overall MBU cross-sections that were observed with technology scaling are not a critical issue in SOI SRAMs that use ECC circuits. David F. Heidel received his B.S. degree in physics from Miami University in 1974, and his M.S. and Ph.D. degrees in physics from The Ohio State University in 1976 and 1980 respectively. In 1980, he joined IBM’s Research Division, at the Thomas J. Watson Research Center in Yorktown Heights, NY, working on Josephson superconducting technology. Since

Reducing Soft Error Rate of SoCs Analog-to-Digital Interfaces With Design Diversity Redundancy

In this article, a commercial programmable system-on-chip (PSoC 5, from Cypress Semiconductor) is tested under heavy-ion irradiation with a focus on the analog-to-digital interface blocks of the system. For this purpose, a data acquisition system (DAS) was programmed into the device under test and protected with a design diversity redundancy technique. This technique implements different levels of diversity (architectural and temporal) by using two different architectures of converters (a ΣA converter and two successive approximation register (SAR) converters) operating with distinct sampling rates. The experiment was performed in a vacuum chamber, using a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> O ion beam with 36-MeV energy and sufficient penetration into the silicon to produce an effective linear energy transfer (LET) of 5.5 MeV/mg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at the active region. The average flux was approximately 350 particles/s/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for 246 min. The individual susceptibility of each converter to single-event effects is evaluated, as well as the whole system cross section. Results show that the proposed technique is effective to mitigate errors originating at the converters since 100% of such errors were corrected by using the diversity redundancy technique. Results also show that the processing unit of the system is susceptible to hangs that can be mitigated using watchdog techniques.

A Comparison of Electron, Proton and Gamma Irradiation Effects on the I-V Characteristics of 200 GHz SiGe HBTs

Total ionizing dose effects induced by 1 MeV electron and 5 MeV proton on the dc electrical characteristics of 200 GHz silicon germanium heterojunction bipolar transistors (SiGe HBTs) were investigated. These results were compared with 60Co gamma irradiation results to understand the linear energy transfer effects on the electrical characteristics of SiGe HBTs. The different electrical parameters like forward and inverse mode Gummel characteristics, excess base current ( ${\boldsymbol \Delta } I_{\mathbf {B}}$ ), current gain ( $\boldsymbol {h}_{\mathbf {FE}}$ ), and output characteristics ( $\boldsymbol {I}_{\mathbf {C}}$ - $\boldsymbol {V}_{\mathbf {CE}}$ ) were systematically studied before and after irradiation. The electrical characteristics of irradiated SiGe HBTs degrade with an increase in total dose. The more degradation in device parameters was observed in case of 5 MeV proton irradiated HBTs when compared to other radiations. The irradiated devices were also subjected to isochronal annealing to analyze the recovery of electrical parameters.

Effect of linear energy transfer on the scintillation properties of Ce:Gd3Al2Ga3O12

We analyzed the scintillation properties of Ce:Gd3Al2Ga3O12 (GAGG), which are dependent on linear energy transfer (LET). The rise in the scintillation temporal profiles was slow at high LET, whereas the decay did not significantly depend on LET. The slow rise at high LET could be explained as follows. Competition among multiple excited states for energy transfer to a nearby Ce3+ ion led to failure in energy transfer for some of the excited states. Subsequent competition occurred among the residual excited states for energy transfer to the Ce3+ ions located far from the original position of the excited states, followed by quenching.

TCAD Simulation of Single-Event-Transient Effects in L-Shaped Channel Tunneling Field-Effect Transistors

Tunnel field-effect transistors (TFETs) have promising structures for future ultrascaled devices thanks to their capability in reducing swing threshold and short channel effects. In this paper, Si-based L-shaped channel TFETs (LTFETs) with buried oxide layers subjected to heavy-ion irradiation are scrutinized using Technology Computer-Aided Design simulation for the first time. The effects of linear energy transfer and voltage bias on single-event effects (SEEs) are investigated. Results show that the peak value of drain current in LTFET reaches up to $2.59 \times 10^{-4}$ A at $10 ~\text {MeV}\cdot \text {cm}^{2}$ /mg, which is much higher than the on-state current at $V_{d} = 0.5$ V. Moreover, it indicates that LTFET is more sensitive to SEE than fully depleted silicon-on-insulator MOSFET with back-plane layer. Meanwhile, overall analysis shows that the charge collection process in LTFET device is mainly due to the drift–diffusion mechanism and the bipolar amplification effect can be eliminated. A part of the hole produced by ion strikes will diffuse from the body into the drain region and help reduce the duration of transient. Moreover, by simulating heavy-ion strike in the lateral and vertical channels in LTFETs, the tunneling junction was first confirmed as the most sensitive part of the TFET against heavy-ion impacts, where the highest electric field in the device is found. These findings give a new insight into the SEE in TFETs, which can provide guidelines for the future radiation-hardened applications for TFET-based circuits.

Influence of Tilted Angle on Effective Linear Energy Transfer in Single Event Effect Tests for Integrated Circuits at 130 nm Technology Node**Supported by the Key Laboratory of Microsatellites, Chinese Academy of Sciences.

A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130 nm CMOS bulk Si and silicon-on-insulator (SOI) technologies. The effectiveness of linear energy transfer (LET) with a tilted ion beam at the 130 nm technology node is obtained. Tests of tilted angles θ = 0°, 30° and 60° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40MeVcm2/mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cos θ, furthermore the effective LET for SOI is more closely in inverse proportion to cos θ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cos θ very well, which is also specifically explained.

Analysis of single event transient pulse-width in 65 nm commercial radiation-hardened logic cell

With the critical charge reduced to generate a single event effect (SEE) and high working frequency for a nanometer integrated circuit, the single event effect (SET) becomes increasingly serious for high performance SOC and DSP chips. To analyze the radiation-hardened method of SET for the nanometer integrated circuit, the n+ guard ring and p+ guard ring have been adopted in the layout for a 65 nm commercial radiation-hardened standard cell library. The weakest driving capacity inverter cell was used to evaluate the single event transient (SET) pulse-width distribution. We employed a dual-lane measurement circuit to get more accurate SET’s pulse-width. Six kinds of ions, which provide LETs of 12.5, 22.5, 32.5, 42, 63, and , respectively, have been utilized to irradiate the SET test circuit in the Beijing Tandem Accelerator Nuclear Physics National Laboratory. The testing results reveal that the pulse-width of most SETs is shorter than 400 ps in the range of LETeff from to and the pulse-width presents saturation tendency when the effective linear energy transfer (LETeff) value is larger than . The test results also show that the hardened commercial standard cell’s pulse-width concentrates on 33 to 264 ps, which decreases by 40% compared to the pulse-width of the 65 nm commercial unhardened standard cell.

The Effect of Linear Energy Transfer, Particle and Energy Fluence on Renal Surface Area during Abdominal CT Scan

The quantities that determine the relative image noise level by either increasing or reducing its value are photon quality (kVp) and photon quantity (mAs). This study is to determine the effect of LET, energy and particle fluence on the renal surface area during abdominal CT scan. The method involve extracting three exposure parameters from image data using MVL DICOM application software including: kVp, mA and scan time. The kVp or the photon peak energy which is applied in the A-P direction during abdominal CT scan was used to estimate linear energy transfer. While the particle fluence and the energy fluence were estimated from the effective mAs and the kVp on the total renal surface respectively. The effective mAs were estimated by dividing the mAs by the average pitch factor of approximately 0.813. In all the examinations, the average protocol setting in terms of exposure time and kilovolts peak were 500s and 120keV respectively. While the average protocol in all the centers recorded a mean effective milliamp second (mAs) of 59.27 mAs and tube current of 94.22A. The influence of these parameters on abdominal scan depends on the scan time, scan scope, the size of the renal surface area (RSA) which has varied values. The effects of effective mean mAs per unit mean renal surface area, described as mean effective particle fluence were 1.32mAs/cm2 and 1.50 mAs/cm2 for male and female respectively. The energy fluence, which is the photon energy per unit renal surface area estimated to have a mean value of 4.02 keVcm-2 and 4.51 keVcm-2 for male and female respectively. In addition, the maximum and minimum variations of all the measured parameters. The LET, which described the lost in photon energy as it traverses across the renal tissues in the A-P direction was estimated, with a mean value of 2.60 keV/µm and 2.67 keV/µm for male and female respectively. The maximum and minimum LET values were 4.49 keV/µm and 1.90 keV/µm for male and 5.26 keV/µm and 1.98 keV/µm for female respectively. The maximum measured values were below the critical LET values estimated to be between 15 to 20 keV/µm. These estimated risk parameters were used to predict the effect on abdominal and kidney tissues using the various modeled equations.

Analysis of linear energy transfer effects on the scintillation properties of Bi4Ge3O12 crystals

We analyzed the linear energy transfer (LET; energy deposited onto the target per unit length) effects on the scintillation properties of Bi4Ge3O12 (BGO) with an emphasis on the dynamical aspect. We irradiated BGO with 20MeVH±, 50MeVHe±, and 220MeV C5+. We observed that the rise and the decay of the scintillation temporal profiles are faster at higher LET. The faster decay at higher LET is attributed to the competition between the radiative transition of self-trapped excitons (STEs) localized at Bi3+ ions and the quenching caused by the interaction between STEs. The faster rise can be explained in terms of the competition between the quenching caused by the interaction between excited states and the formation of the STEs.

Using TCAD Modeling to Compare Heavy-Ion and Laser-Induced Single Event Transients in SiGe HBTs

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) models are used in technology computer aided design (TCAD) to investigate single event transients induced by heavy-ion broadbeam and pulsed-laser two-photon absorption sources. A comparison between transient waveforms is provided, the proper extraction of heavy-ion broadbeam transients is discussed (along with circuit implications), and basic laser strike profiles are implemented in TCAD to provide insight into future design practices for simulation software to be used to describe laser-induced upsets in terms of an effective linear energy transfer (LET).

Cell kill by megavoltage protons with high LET

The aim of the current study is to develop a radiobiological model which describes the effect of linear energy transfer (LET) on cell survival and relative biological effectiveness (RBE) of megavoltage protons.By assuming the existence of critical sites within a cell, analytical expression for cell survival S as a function of LET is derived. The obtained results indicate that in cases where dose per fraction is small, is a linear–quadratic (LQ) function of dose while both alpha and beta radio-sensitivities are non-linearly dependent on LET. In particular, in the current model alpha increases with increasing LET while beta decreases. Conversely, in the case of large dose per fraction, the LQ dependence of on dose is invalid.The proposed radiobiological model predicts cell survival probability and RBE which, in general, deviate from the results obtained by using conventional LQ formalism. The differences between the LQ model and that described in the current study are reflected in the calculated RBE of protons.

Addressing Angular Single-Event Effects in the Estimation of On-Orbit Error Rates

This study describes complications introduced by angular direct ionization events on space error rate predictions. In particular, prevalence of multiple-cell upsets and a breakdown in the application of effective linear energy transfer in modern-scale devices can skew error rates approximated from currently available estimation models. This paper highlights the importance of angular testing and proposes a methodology to extend existing error estimation tools to properly consider angular strikes in modern-scale devices. These techniques are illustrated with test data provided from a modern 28 nm SRAM-based device.