April 2006
NASA JSC Radiation Detection Workshop April 6-7, 2006
Combined Ion and Neutron Spectrometer for Space Applications
(CINS)R. H. Maurer1, Cary Zeitlin2 , D. K. Haggerty1
D. R. Roth1, J. O. Goldsten1, 1Space Department, The Johns Hopkins Applied Physics Laboratory
Laurel MD 2Lawrence Berkeley National Laboratory, Berkeley, CA
April 2006
CINS concept
I. Combine a charged particle telescope and neutron spectrometer into a single unit with common electronics.
II. Charged particle telescope: silicon + plastic scintillators + BGO scintillator. • Mars Odyssey MARIE instrument design
with many improvements.III. Neutron spectrometer: Low, medium, and
high-energy detectors developed under previous NSBRI grants.
April 2006
Project Goals I
• CINS will monitor the complete particle radiation environment
• After instrument detector procurement, fabrication and calibration are complete, CINS will be used in ground based accelerator experiments using heavy ions, protons and neutrons to determine energy spectra • The dose or dose equivalent calculated from the CINS
energy spectra will be compared with the measured LET or dose of TEPCs or dosimeters to ascertain the limitations in response of the latter devices.
April 2006
Project Goals II
Evaluate detector and telescope performance characteristics including noise, resolution and event rate.
Extensive testing at accelerator facilities.• Emphasis on heavy ion beams and thick
target collisions producing charged particle fragments and neutrons.
In second generation instrument reduce size, mass, power.
April 2006
Technical Approach
1. Create a charged particle telescope system that improves the MARIE instrument flying on the Mars Odyssey mission.
a) eliminate the gain saturation for heavy ions with LET> 35 keV/micron;
b) increase the dynamic range of the MARIE instrument by a factor of 10-20 (up to 1000:1) to include protons with energies above 100 MeV;
c) increase the maximum event rate of MARIE by at least a factor of 10 above the current limit of 3 Hz.
2. Fabricate, evaluate and calibrate the Eljen 454 scintillator detector system for medium energy neutrons from 1-15 MeV.
3. Develop the instrument electronics design based on the Gamma Ray Neutron Spectrometer (GRNS) instrument for the MESSENGER mission.
April 2006
CINS Tasks and Milestones
The main initial tasks to date in 05/06 • Refurbished 4cm diameter X 5mm thick silicon
detectors by re-drifiting and applying guard rings • Designed and procured an Eljen boron-loaded
scintillator sized to detect up to 15 MeV neutrons producing a cross over region with the higher energy thick silicon neutron detector
• Modeled the charged particle telescope design with GEANT 4
• Executed experiments at NSRL on 3/25.
April 2006
Refurbished Thick Silicon Detectors
Refurbished thick silicon detector (4 cm X 5 mm) re-drifted with lithium to reduce noise (30 keV) and with guard ring added to define active diameter (3.7cm).
April 2006
Charged Particle Telescope I
Conceptual design of 7 detector charged particle telescope determined by modeling; BGO detector is 3 cm thick
April 2006
Charged Particle Telescope II
Similar to MARIE in that the 4 thick Si detectors provide particle identification and LET spectra. • MARIE dynamic range problem fixed.
BGO adds mass, stops protons up to energy of 150 MeV; makes the stack asymmetric for directionality.
Plastic scintillators used as triggers & simple counters; helpful in high-rate environments.
April 2006
Charged Particle Telescope Simulations
A shows the energy deposition in the thick BGO detector on the abscissa with the energy deposition in the last Si SSD on the ordinate. The vast majority of the protons can be separated from the electrons. With the BGO this simulation shows that protons up to ~300 MeV can be uniquely identified.
B and C show that a proton depositing ~80 MeV in the BGO yields primary and penetrating depositions in SSD4 of 1 MeVresolution.
April 2006
Charged Particle Telescope Directionality
Figure shows asymmetry of thetelescope yields directionalitya) Particles from the front end
deposit larger ranges of energy in SSD4 and the BGO.
b) Particles from the back end deposit smaller ranges of energy in SSD1 and Scint1. Electrons incident on the back end are absorbed by the BGO.
April 2006
Silicon Detector Performance in Fragmentation Experiment
1) Argon-beam experiment at CHIBA, Japan: fragments and surviving primaries detected with re-drifted 5mm thick Si(Li) detectors.
2) Deposited energy ∝ (Z2/v2), with v2 ~ const.3) Even with old electronics, easily cover the 400:1
dynamic range in a single channel.• CINS will have 2 different gains per Si detector.
4) Resolution sufficient to resolve peaks from detection of multiple fragments in coincidence.• E.g., effective Z = (62+22)1/2 = 6.3 from
coincidence of C and He.
April 2006
Charged Fragment Spectra from Heavy Ion Experiments
F ra g m e n ts F ro m 4 0 A r + 1 2 C R e a c t io n s a t 6 5 0 M e V /a m u
F r a g m e n t C h a r g e0 2 4 6 8 1 0 1 2 1 4 1 6 1 8
# ev
ents
5 0 0
1 0 0 0
1 5 0 0
2 0 0 0
2 5 0 0
3 0 0 0
3 5 0 0
L o w -g a in c h a n n e l
Coincidence of 3 He fragments
Subsidiary peaks from non-leading He in coincidence with heavier fragments
April 2006
Neutron Spectrometer(originally aimed at ISS)
Three components to monitor interior environment:• 3He tube for low energy (thermal to 1 MeV)• Boron-loaded plastic scintillator (Eljen) for medium
energy (1-15 MeV)• Thick Si(Li) detector with anti-coincidence shield
for high energy (12-600 MeV)• Unfolding to get incident neutron energy
spectrum from deposited energy spectrum is maximum likelihood method.
April 2006
LANSCE High Energy Neutron Blind Experiment
Comparison of the measured high energy neutron spectrum >20 MeV (red) from the 5mm thick silicon detector with the Los Alamos calculation for the beam-target configuration
0E+0
1E+5
2E+5
3E+5
4E+5
5E+5
6E+5
0 200 400 600 800Neutron Energy (MeV)
Neu
trons
/cm
^2
LANL CalculationJHAPL
April 2006
Effect of Shielding Materials200 & 500 MeV Proton Collisions
1E-08
1E-07
1E-06
1E-05
1E-04
1E-03
0 100 200 300 400 500
Neutron Energy
n/p
Inte
gral
Spe
ctru
m
Poly 200 MeV 0 DegAl 200 MeV 0 DegCarbon 200 MeV 0 DegPoly 500 MeV 30 DegAl 500 MeV 30 DegCarbon 500 MeV 30 Deg
April 2006
Typical 6 MeV Neutron Waveforms from Bicron 454 Scintillator
Wave Forms
0
500
1000
1500
2000
0 5 10 15 20 25
Time (uS)
AD
C C
ode
(LS
B)
Recoil OnlyRecoil + Capture
April 2006
NSRL Detector ConfigurationMarch 25,2006
April 2006
Balloon Flight Detectors
April 2006
CINS Block Diagram
He-3 Tube Pre-
Am
p
Low Energy System
10 MhzADC (3)
AnalysisFPGA
DualHVPS
Si BiasAnti-Coincidence/He-3
Negative Telescope BiasDual
HVPSPositive Telescope Bias
High Energy System
Si
Anti-coincidence Pre-
Am
ps
Charge Particle Stack
Pre-
Am
ps (8
)
10 MhzADC (9)
AnalysisFPGA
RTX-2010(Rad-Hard)
Microprocessor
Memory
ControlFPGA
Serial I/F38.4 kbps
1 Hz Time Sync
LVPS(+/- 12V)(+/- 5V)
Current &VoltageMonitors
HSKADC
Power I/F(22-36 V)
Serial Data I/F
BC454 Pre-Amp
Medium Energy System
April 2006
Heritage
• Low- and medium-energy neutron sensors used on Mars Odyssey, Mercury MESSENGER.
• JHU-APL built electronics for MESSENGER Gamma Ray/Neutron Spectrometer (GRNS).
• High-energy sensor used on balloon flights and thick target accelerator experiments.
• Charged-particle detectors from LBNL SSDL which built detectors for Voyager, ACE/CRIS, MARIE, etc.
April 2006
Related Projects/Next Steps
• We delivered a version of the NSBRI Neutron Spectrometer for the Deep Space Test Bed (DSTB) balloon flight in December 05. The contract was funded for $272,000 by MSFC. Completion of integration with gondola is scheduled for April 06.
• 3/25/06 NSRL run made for individual Si(Li) detector evaluations and thick Al target collisions
• In 2006 procure BGO scintillator for telescope, complete mechanical design and begin assembly.
• Summer 06: calibrate Eljen 454 scintillator at RARAF. • Spring 07 NSRL run for scintillator evaluations and
first test of telescope.• Continue GEANT4 modeling (D. Haggerty).
April 2006
Publications
• R.H. Maurer, J. D. Kinnison and D. R. Roth, “Neutron Production from 200-500 MeV Proton Interaction with Spacecraft Materials,” Radiation Protection Dosimetry 2005, 116, No. 1-4, 125-130.
• R. H. Maurer, D. R. Roth, J. D. Kinnison, D. K. Haggerty and J. O. Goldsten, “The NSBRI/APL Neutron Energy Spectrometer,” accepted for publication in Johns Hopkins APL Technical Digest 2005.
• R.H. Maurer, C. J. Zeitlin, D. K. Haggerty, D. R. Roth, J. O. Goldsten, “Compact Ion and Neutron Spectrometer (CINS) for Space Application,” 2005 IEEE Nuclear Science Symposium Conference Record, N14-48, pp 428-432, Puerto Rico, 24-27 October 2005.
• C. J. Zeitlin et al., "Overview of the Martian Radiation Environment Experiment", Adv. Space Res. 33, No. 12, 2204-2210, 2004.
