Bubble Detector Characterization for Space Radiation

Transcription

1 Bubble Detector Characterization for Space Radiation B.J. Lewis, A.R. Green, H.R. Andrews*, L.G.I. Bennett, E.T.H. Clifford*, H. Ing*, G. Jonkmans*, R. Noulty* and E.A. Ough Royal Military College *Bubble Technology Industries 8 th Workshop on Radiation Monitoring for the ISS Berkeley, California September 3-5, 2003

2 Outline Introduction - Space Dosimetry Ground-Based Accelerator Study

3 EV-CPDS: Extra- Vehicular Charged Particle Spectrometer IV-CPDS: Intra- Vehicular Charged Particle Spectrometer TEPC: Tissue Equivalent Proportional Counter RAM: Radiation Area Monitors (TLDs) PRD: Passive Radiation Dosimeter (TLDs) CPD: Crew Passive Dosimeter (TLDs, PNTD) Active instrument real-time telemetry Active instrument no real-time telemetry Passive instrument Space Radiation Monitoring* EV-CPDS IV-CPDS TEPC RAMs CPDs TEPC PRDs CPDs * Adapted from: M. Golightly, Initial Briefing to Astronauts Radiation Exposure During Space Missions, 1998 Astronaut Candidate Class, NASA-JSC, June 10, 1999.

4 Space Dosimetry and Exposures* Type Program Measurements Crew Personnel Dosimetry: TLD-100 All Programs Absorbed dose TLD-300, 600, 700 STS, and ISS Absorbed dose CR-39 or other Nuclear plastic Apollo, Skylab, STS, STS, track detectors Mir Fluence vs. LET or Z Fission Foils Apollo, STS Neutrons Area dosimetry: TLD-100 STS, Mir, ISS Absorbed dose TLD-300, 600, 700 STS, ISS Absorbed dose CR-39 or other Nuclear plastic track detectors Fluence vs. LET or Z Fission Foils Apollo, STS Neutrons Active Ionization Chambers Apollo, Skylab Absorbed dose TEPC STS, Mir, ISS Lineal energy, dose, dose equivalent Z,E Telescope Mir, STS, ISS Fluence vs. Z and E Bonner Spheres STS, ISS Neutrons Bubble detectors STS Neutrons? µgy/d solar max) (~2 x greater during solar min) ~ 60 msv for 140 days (CNSC terrestrial limits are 20 msv/y) *Adapted from: F. Cucinotta, Organ Dose Estimates for Astronauts, CSA Training with SRAG, NASA-JSC, January 27-31, 2003.

5 Experimental Equipment Tested Extended Range ( Space Pack ) Bubble Detector Spectrometer (BDS) Normal BDS + high threshold detectors (20 and 100 MeV), Bi Loaded: 209 Bi(n,f) Temperature-Compensated Bubble Detectors (BD-PND) Nuclear Fragmentation Separation Experiment (NFSE) Ground-Based Accelerator Measurements CERF (Integral neutron field simulant space spectrum) HIMAC (180 MeV/u N & 500 MeV/u Ar ions) TRIUMF (81.7 MeV p)

6 Neutron-Sensitive Bubble Detector M H = R H = R φ de φ E h φ de φ E

7 Response-to-Fluence Functions R φ for BD-PND and BDS BD-PND Noulty (1996) Buckner & Noulty (1996) Tume et al. (1998) PTB Measurements (2000) Proposed Function R Φ (bubbles cm 2 n -1 ) Neutron Energy (MeV)

8 Neutron Spectra φ Airline (Goldhagen) Accelerator (*0.0547) MIR Station (Lyagushin) 0.8 Spallation Eφ E (cm -2 s -1 ) Evaporation Neutron Energy (MeV) Airline and Accelerator Shielding: Multisphere spectrometer MIR: nuclear photoemulsion, fission foils, recoil protons in organic scintillator and reaction products from CsI(Tl) scintillation crystal

9 Ground-Based Calibration at CERF SWENDI Ionization Chamber TEPC NFSE Bubble Detectors

10 Nuclear Fragmentation Separation Experiment (NFSE) Charged particle signature accompanies ~ 10% of events registered in BD - Agreement with FLUKA: charged hadron (p, π) fluence rate one order of magnitude less than neutrons BD-PND (260±50 psv/pic) vs CERF reference value (265±5 psv/pic) - Supports BD-PND calibration factor R H NFSE needs space qualification

11 CERF Neutron Spectrum Comparison of BDS with Multisphere Spectrometer 0.3 Multisphere Spectrometer Bubble Detector Spectrometer 6 Eφ E (cm -2.pic -1 ) Eφ E /10 5 (cm -2 ) Neutron Energy (MeV)

12 MIR Neutron Exposure (Nov 92-Jan 93) BDS: 150 µsv/d (with CERF calibration factor) TLD Measurements (Badhwar) 260 µgy/d x 2.5 (average TEPC quality factor) x 20% (neutron fraction of charged particle dose equivalent) = 130 µsv/d

13 BD Testing at HIMAC (Ar and N ions) Pressure Control Bubble Detectors Temp. Control

14 BD Testing at HIMAC (Ion Beams) Response of BD: LET vs S Compare with d Errico theory Super Heat: S = T T c T T b b

15 BD LET Vs Super Heat Response 800 LET (KeV/micron) PR50 B50 (30 deg.) Butane 100 (30 deg.) d'errico B80 PE20 (30 deg.) PR35 B65 (30 deg.) B30 PE70 (50 deg.) B10 PE90 (50 deg.) Argon Beam REDUCED SUPERHEAT 250 PR50 B50 (25 deg.) PR80 B20 (40 deg.) 200 d'errico LET (KeV/micron) T = 49 degree C P = 43 PSIA PR35 B65 (40 deg.) B100 (40 deg.) B50 PE50 (50 deg.) B40 PE60 (50 deg.) Nitrogen Beam REDUCED SUPERHEAT

16 Comparison Among Nuclei LET (KeV/micron) Nitrogen PR50 B50 (25 deg.) d'errico Argon PR50 B50 (30 deg.) REDUCED SUPERHEAT Effect of track structure?

17 Temperature Compensated BD-PND (S = 0.3) BD-PND exposed to Ar beam BD-PND show constant response over broad range of temperature Response of BD-PND -LET Ar = 201 ± 40 kev/µm -LET N = 116 ± 40 kev/µm

18 BD Testing at TRIUMF (Protons) Bubble Detectors

19 BD Response to Protons 81.7 MeV protons 90 kev/micron Straggling 2 mm

20 Comparison Among Nuclei Proton Nitrogen Argon

21 Conclusion Better understanding of BD response to charged particles - Modulate response of BD to desired LET - Super heat alone insufficient to describe LET response (d Errico curve) - BD-PND response constant over wide temperature range NFSE successfully tested for charged particle discrimination BDS can be used for (high-energy) neutron spectral measurements - Further testing required with Bi-loaded detectors

22 Acknowledgments M. Neiman and A. Mortimer (CSA), M. Silari and E. Dimovasili (CERF), M. Takada and H. Kitamura (HIMAC), E. Blackmore (TRIUMF) Funded by Space Life Sciences program of CSA