christina l. howe 1 , robert a. weller 1 , robert a. reed 1 ,

Measurement and Simulation of the Variation in Proton-Induced Energy

Deposition in Large Silicon Diode Arrays

Christina L. Howe1, Robert A. Weller1, Robert A. Reed1, Brian D. Sierawski2, Paul W. Marshall3, Cheryl J. Marshall4,

Marcus H. Mendenhall5, Ronald D. Schrimpf1, and J. E. Hubbs6

1. Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 372352. Institute for Space and Defense Electronics, Vanderbilt University, Nashville, TN 372353. Consultant, Brookneal, VA 245284. NASA-GSFC, Greenbelt, MD 207715. Free-Electron Laser Center, Vanderbilt University, Nashville, TN 372356. Ball Aerospace & Technologies Corp., Albuquerque, NM 87117

Outline• Background• Motivation• Experimental Setup• Modeling Description• Results

– Simulation compared with experimental results

– Contribution from reaction mechanisms

– Event rate calculation

• Conclusions

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Background• Focal plane arrays (FPAs)

often used on satellites planned for long orbits in harsh proton environments

• FPAs Advantages– Flexible, reliable, low cost,

high-density resolution, on-chip signal processing, and more radiation tolerant to protons than charge coupled devices (CCDs)

Detector Array

In In In

ROIC

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Basic hybrid FPA

Motivation• Proton events contribute to

device noise floor• Better understanding of how

radiation-induced energy deposition occurs will improve prediction techniques

• Accurate modeling helps predict on-orbit response

• We will show a high-fidelity prediction method based on Monte Carlo simulations and a mathematical model

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

http://sohowww.nascom.nasa.gov/gallery/Movies/flares.html

Experimental Setup

• Hybrid FPA consisting of a silicon p-i-n 128 × 128 detector array with hardened CMOS readout integrated circuit (ROIC)

• Full radiometric characterizations were performed– Dark current, noise, responsivity, and sensitivity

• Irradiated with 63 MeV protons at 45°• Biased to 15V resulting in full depletion• Exposed at 233 K

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Modeling Description

• MRED (Monte Carlo Radiative Energy Deposition), a GEANT4 based tool, used for simulation

SensitiveVolume

45°

63 MeV Proton

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

• TCAD simulations revealed RPP assumption was sufficient to estimate device response to radiation

Modeling Description• Each event in Monte Carlo simulation represents

only one primary particle hit one pixel, but…– Non-negligible probability of multiple hits on a single

pixel (pile up) exists

– Non radiation induced noise in experimental data

(exp)n_TimeIntegratioFlux(exp)(sim)

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Bin_WidthGauss

NOISE

Pile Up

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

µ = 0.08σNOISE = 3

Before Pile Up

After Pile Up

Results

Statistical floor of

experimental data

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Constant-LET and Path Length Distribution Calculation

• Does not predict occurrence of large energy depositions

• Does not predict shape of curve

LengthPath LETositedEnergy_dep

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Reaction Mechanisms

• Nuclear reactions dominate above 500 keV

• Coulomb scattering does not contribute significantly here

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Event Rate Simulations

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

• Proton environments from CREME

• GEO – peak five minutes and worst week

• ISS – space station orbit, apmin8

GEO Event Rate Simulations

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

ISS Event Rate Simulations

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays

Conclusions

• The on-orbit response can be predicted with greater detail than available through experiment at energies greater than 700 keV

• Energy events greater than 130 keV are not predicted by path length calculation for this device

• Nuclear reactions dominate the event rate at energies greater than 3 MeV

christina.l.howe@vanderbilt.eduMeasurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays