PSI’s Space Radiation Instrumentation

Radiation Detection & Dosimetry 

6-7 April 2006

G. E. Galica

Physical Sciences Inc.

20 New England Business Center

Andover, MA 01810-1077

www.psicorp.com

Slide 2
PSI Rad Sensor Experience

• PSI has developed several generations of charged particle sensors
– Space science
– Spacecraft & microelectronics survivability
– Spacecraft operations support
• SDOM [JAXA] – Gen1
– 1-200 MeV protons, 0.5-10 MeV electrons, alphas, Heavy ions - 32 particle-energy bins
– 2 sensors currently flying (GEO & GTO), 1 awaiting launch on JEM
• LPD [USEF(Japan)] – Gen2
– 1-150 MeV protons, 0.3-20 MeV electrons, alphas/heavy ions - 12 particle-energy bins
– 1 sensor currently flying (1000 km polar), follow-on sensor launch 2007
• CEM [NASA LWS SET] – Gen2
– Modified LPD
– Launch 2009
• HIPS [AFRL] – Gen3
– LPD derivative
– High energy electrons and protons, Imaging sensor
– Development started (launch 2009 on DSX)
• LIPS [AFRL]
– 20-2000 keV protons and electrons
– Imaging sensor, 12 energy bins x 8 angular bins
– Launch 2009 on DSX
• PSI has flown > 20 instrument and experiments since 1991 on satellites, shuttle and space station

Slide 3
PSI Rad Sensor Design Objectives & Data Quality

• PSI GEN1& GEN2 radiation sensors had several performance goals 
that have now been demonstrated on orbit:
• Single sensor to detect protons, electrons, alphas, heavy ions
• Large throughput (A omaga) – up to 0.3 cm2 sr
– Results in high count rates, efficient detection of small populations of particles, good 
counting statistics
• High count rate – up to 200 kcps
– Does not saturate during solar storms
• Good particle discrimination
– Cross-contamination between electrons and protons can be a significant problem
– SDOM & LPD (GEN1&2 sensors) achieved <10 to the -4 contamination
– Achieved through sensor design and on-board processing
• High accuracy calibration and validated sensor model
– Returning fully calibrated data from sensor turn-on
• Flight proven technology on multiple orbital missions
• High quality, calibrated data received from turn-on

Slide 4
LPD – Light Particle Detector (GEN-2)

• Designed for and flying on the SERVIS-1 satellite (Japan)
– Space Environment Reliability Verification 
Integrated System
– Orbital mission Oct03-present
– SERVIS-2 follow-on launch 2007
– CEM for LWS-SET
• Baseline Energy Range
– protons: 1 to 150 MeV (6 bins)
– electrons: 0.3 to 10 MeV (4 bins)
– alphas: >12 MeV (1 bin)
– ions: >3 MeV/nucleon (1 bin)
• Large G-factor/high count rate
– 0.2 cm2sr
– 200 kcps
• FPGA-based processing
• Extensive ground calibration & modeling
• Physical parameters
– 4 kg (fully redundant)
– 7 W (HiRel/RadHard)


image of Gen-2 Light Particle detector


Slide 5
Generic Block Diagram

• Combination of multiple detectors: SSDs and scintillator
• AntiCoincidence Scintillator rejects side penetrating particles 
• Collimator defines acceptance angle for low energy particles
• High-speed analog circuitry and ADC (12-bit) enables 200 kcps rate
• High-speed, FPGA-based processor reduces data volume


Generic Block Diagram with labels:
Collimator, Foil Window, SSD1, SSD2, Anti-Coincidence Scintillator Passive Shielding, CSP/Peahold, Calibration Telemetry Drivers, S/C Telemetry, DC/DC Converter, Filter, S/C Power.
FPGA 
- Event Detection
- Particle Type
- Energy Analysis
- Binning
- Spacecraft Interface

Slide 6
Modeling and Calibration

• All PSI sensors are modeled using the GEANT4 code 
– no free parameters
• The model is validated with 
calibration data
– Sensors are calibrated over nearly 
their entire particle-energy range
• We use the model to:
– develop and refine the sensor and 
algorithm design
– interpolate/extrapolate sensor response to uncalibrated regimes
– predict on-orbit performance
– interpret orbital data

diagram of SERVIS with label 10 MeV electrons
graph of Proton Scintillator Respnse with proton energy range 0 - 160 MeV


Slide 7
Sensor Calibration & Modeling

• PSI extensively calibrates its radiation sensors
– over nearly their entire particle / energy ranges 
• We develop full 3D sensor models to describe performance
– GEANT4 based models
– No free parameters
• We validate the models with ground calibration data
• Use the models for to interpolate and extrapolate sensor performance uncalibrated regions
– Design phase
– Interpretation of orbital data


Particle	Energy (MeV)	Facility

Proton		0.03-1.0	UNT
		0.9-1.7		NASA GSFC
		7.5-31		Yale Wright NSL
		15-225		NPTC
		50-250		IUCF

Electron	0.03-0.4	NIST C-W
		0.5-2.0		NIST VdG
		7-32		NIST MIRF
		
Alpha		10-50		Yale Wright NSL

Ion (C)		15-120		Yale Wright NSL


Slide 8
SERVIS LPD – 2 Dec 03

• On 2 Dec 2003, SERVIS LPD detected a sudden, spatially distinct enhancement of low-energy protons
• Low energy protons (1 to 12 MeV) enhanced first
• Enhancement in higher energy protons (12 to 25 MeV; 25 to 50 MeV) occurred after a delay
• Small changes in electron activity
• SAA proton flux was also enhanced


graph of protons - 2 Dec 03
with axis Flux (cm-2 s-1) with range 1.E+01 to 1.E+07 to UT (hh:mm) with range 8:00 to 20:00
labels p1 - 1.5-12 MeV, p2 - 13-25 MeV, p3 - 25-37 MeV, p4 - 38 - 53 MeV, p5 - 53-96 MeV, p6 - 96-150 MeV
graph of electrons - 2 Dec 03
with axis Flux (cm-2 s-1) with range 1.E+01 to 1.E+07 to UT (hh:mm) with range 8:00 to 20:00
labels e1 - 0.3-1.5 MeV, e2 - 1.7-3.4 MeV, e3 - 3.4-636 MeV, e4 - >6.6 MeV

Slide 9

Electron / Proton contamination

• LPD and SDOM both exhibit very small amounts of contamination by low energy electrons


• <10 to the -4 contamination of low-energy protons by electrons

graph of Electon / Proton contamination 1000 km, 98 deg, 01Dec03
axis labels bin counts with range 1.E+00 to 1.E+06 to time (hh:mm) with range 9:20 to 10:20
electrons (0.3-1 MeV)
protons (1-10 MeV) 

SERVIS-1 LPD


Slide 10
SDOM – Standard Dose Monitor (GEN-1)

• PSI and MELCO developed a charged particle spectrometer
• Delivered 3 flight units for NASDA (Japan) satellites
– MDS1: GTO
– DRTS: GEO
– JEM: LEO
• Characterizes the higher energy orbital radiation environment
– protons: 1 to 200 MeV, 12 bins
– electrons: 0.4 to 20 MeV,5 bins
– alphas: 7 to 150 MeV, 4 bins
– ions: >1.5 MeV/nucleon
• High count rate
• Excellent rejection of Lo-E electrons

Image of inside an outside of Gen-1


Slide 11
MDS1 SDOM Data

• Two SDOM units currently on orbit
– MDS1: GTO
– DRTS: GEO
• PSI involved in orbital data analysis
• Currently 3 years of DRTS data; 27 months of MDS1 data


Proton Spectr - 22 May 2002 graph of Flux (prot/cm2/sr/sec/Mev) to Time (UT)
labels for -0.9-1.1 MeV, - 1.1-1.5 MeV, - 1.5-2.0 MeV, - 2.0-2.7 MeV, - 2.7-3.7 MeV, -3.7-5.4 MeV, -5.7-8.0 MeV, -7-15 MeV, -11-26 MeV, -22-44 MeV, -40-80 MeV, -90-200 MeV
Electron Spectr - 22 May 2002 graph of Flux (elect/cm2/sr/sec/Mev) to Time (UT)
labels for -0.4-.09 MeV, - 0.9-2.0 MeV, - 1.7-5.0 MeV, - 6-11 MeV, - 10-20 MeV
Alpha/ion Spectr - 22 May 2002 graph of Flux (part/cm2/sr/sec/Mev) to Time (UT)
labels for A - 6.5-12 MeV, A - 13-24 MeV, A - 25-52 MeV, A - 76-144 MeV, H - >1.5 MeV/nucl


Slide 12
DRTS SDOM – GOES Intercomparison

• Compared DRTS-SDOM data to GOES data for complete Oct/Nov 2003 Flare
– Start time: 25 Oct 2003 15:06:43
– End time: 13 Nov 2003 15:27:42
• Mapped SDOM bins onto GOES bins
– Sum over SDOM energy bins
– Time average SDOM data
• Quantitative comparison between GOES and SDOM is quite good
• SDOM not saturated during flare
• SDOM low-energy electron bins not contaminated by high energy protons
• SDOM provides better energy and temporal resolution

graph for Flare 12 25-Oct-2003 15:06:43 to 13-Nov-2003 15:27:42 
Axis values Flux (1.m2-sr sec) with range 10 to the -2 to 10 to the 6th power and Time 
Labels for GOES data and ave SDCM data, p+ > 5 MeV
graph for Flare SDOM A6 & GOES A4+A5 25-Oct-2003 15:06:43 to 13-Nov-2003 15:27:42 
Axis values Flux (1.m2-sr sec) with range 10 to the -2 to 10 to the 6th power and Time 
Labels for GOES data and ave SDCM data, A - 60-250 MeV

Slide 13
DSX HIPS (GEN-3)

design of DSX HIPS (Gen-3) with labels for SSDs, scint, B-Field, collimator, ACS, PCBs
• High-energy Imaging Particle Spectrometer
– Under development for AFRL –DSX mission (COTR: M. Golightly)
– Currently in EM phase
– 2007 delivery; 2009 launch
• Energy Range
– Protons 10 - 300 MeV (8 bins)
– Electrons 0.5 - 30 MeV (12 bins)
• Pitch angle distribution measurement
– 7 x 90 deg FOV
– 16 pixels
• Physical
– 200 x 210 x 120 mm3
– 10.5 W–5 kg 
– 740 bytes/sec


Slide 14
Modular Configuration

• LPD is designed around flight-proven detector and electronics modules
• Modular design enables rapid development of new sensors
– alter energy ranges by changing 
detectors
– alter bin configuration
• Working bench model enables rapid prototyping, calibration and validation of new designs
• Redundant and non-configurations available
• Easily configure systems


image of Modular Configuration with labels for SSD, PMT, SSD-HV PMT-HV, Power, Digital-B , Digital-A, H-0095


Slide 15
LPD Modules

Image of LPD Modules with labels for Telescope, SSD A&B, Scintillator, PMT-HV, SSD Board, PMT Board SSD-HV
image of LPD Modules with labels SSD Module, and Scintillator Module


Slide 16
Reconfiguration of Redundant Systems

• EM modular processors available for rapid prototyping
• We create a sensor with greater capability by reconfiguring the basic redundant system
• 2 detectors - 3 detectors
• 1 processor - 2 processors


PSI PROPRIETARY

design of SERVIS LPD and WINDS Option 2 for reconfiguration of redundant systems. Labels for Collimator, Window, SERVIS LPD SSd Board, HV SERVIS LPD PMT Board, Scintillator, SSD-1, SSD-2, HV, CSP, SERVIS LPD Digital-B, SERVIS LPD Digital-A, DAE TLM, DAE Power and DAE TLM


Slide 17
Advanced Radiation Shielding Materials SBIR

• Develop composites that provide more shielding per gram than Al
• Tailor composition to enhance e or p shielding for specific mission
• 20-30% improvement in shielding
• thermal & mechanical properties
• Sponsor: AFRL Materials


RadFET 

• Commercial partner : Space Systems Loral
• Phase 3 Flight Validation
• Geosynchronous telecom satellite: Estrela Do Sul (2003-present)
• 6 material samples, Al standards, 13 RadFET dosimeters

Graph of Thickness/(Thickness)A* to (g/cm2)/g/cm2)A*
Labels for Ge + W, GE = ZrHz, GE + Ni, GE + TiHz.
2000 x 500 km with 70Deg Incl.


Slide 18
Radiation Shielding Composites

The Goal:
Replace Al, Ti and Be alloys with composite structures that:
• Provide enhanced shielding to x-rays and 
neutrons.
• Provide comparable strength for direct 
replacement in structural applications with 
no weight penalty.
• Can be integrated into multifunctional structures.

Neutron shielding Standard refractory PSI enriched B4C

Advantages

• Light weight/High strength
• High temperature performance High volume fraction of absorbing materials
• Composite architecture
• Economical production process

Neutron shielding graph with Standard refractory
Axis Attenuation range 0 - 1.6 to Energy (eV) with range 10-5 to 10 to +7
Labels for PSI Model, Model Aluminum, Enr BrC Composite, Nat B4C Composite, Aluminum, Refract Composite

Slide 19
Summary

• PSI has several generations of charged particle instrumentation with 
flight pedigree 
• PSI’s radiation instrumentation may be able to support the human exploration requirements
• Modular design and redundancy enable reconfiguration of LPD to serve multiple measurement requirements
– energy range & particle types
– G-factor & count rate
– number of bins
– Processing algorithms
– multiple-axis
• LPD test model (-TM) at PSI enables rapid and efficient breadboarding test and calibration of new configurations
• PSI’s advanced shielding materials may be relevant for human exploration applications