Development of a portable OSL reader for spaceflight activities Eduardo G. Yukihara and Stephen. W.S. McKeever Department of Physics, Oklahoma State University Slide 2 TL and OSL Principles TL = thermally stimulated luminescence OSL = optically stimulated luminescence Valence band and Conduction band diagram indicating Exposure Radiation with arrow pointing to object for Radiation sensor (insulating crystal) Slide 3 TL and OSL Principles diagram with objects representing a clock and storage rectange shape rectangle shape line circle design Circle design Slide 4 TL and OSL Principles design of Readout indicates Thermal stimulation (heating) with Light emission - TL (e.g. blue, UV) Light emission – TL READOUT Thermal stimulation (heating) diagram of input and output TL and OSL principles -no data rectangle shape Slide 5 TL and OSL Principles diagram for readout. Green arrow for light stimulation and light emission (e.g. blue, UV) - OSL Light stimulation(e.g., green) OSL READOUT rectangle diagram rectangle diagram Slide 6 TL and OSL Principles diagram indicating the Laser or LEDs (CW or pulsed) pointing to the Dosimeter (OSLD). OSL through detection filters to PMT Slide 7 The Pulsed OSL (POSL) Technique Akselrod Prot. 81, 167-176 (1999) Pulsed OSL (POSL) Measures OSL emission between stimulation pulses, not during the pulse. Better separation between the signal and the stimulation light. diagrams of measures of OSL emission between pulses. Slide 8 Typical TL and OSL Signals TL graphs of TL outputs for TL normalized to temperature, CW-OSL units to time, and POSL units to time Al2O3:C chips LiF:Mg,Ti TLD-100TL (normalized) Temperature (ΊC) CW-OSL (arbitratry units) POSLpulsed POSL (arbitratry units) Time (s) POSL Slide 9 Typical TL and OSL Signals graphs for TL, CW-OSL, POSL readouts Al2O3:C chips LiF:Mg,Ti TLD-100TL (normalized) Temperature (ΊC) POSLpulsed POSL (arbitratry units) POSLCW-OSL CW-OSL (arbitratry units) Slide 10 Possibility of Re-estimation of doses Akselrod Prot. 81, 167-176 (1999) Can re-read the OSL signal, if the signal is strong enough. (No need to deplete the signal in order to measure it.) graph of re-estimated dose (Gy) to number of 1 second measurements. Slide 11 Why develop OSL fro astronaut dosimetry? • All-optical method lends itself to multiple configurations and devices • High sensitivity • Stable signal (no fading) • Re-read of OSL signal (period dose plus total dose) • Re-setting of signal by bleaching • High reproducibility within a batch (e.g.LuxelTM) • Thin dosimeters (e.g. LuxelTM) for ease of use • Fast readout • Low (electrical) power • High reliability of components • Various on-board readout configurations • Can combine with TLD/PNTD badges, and readers Slide 12 Space & Ground-Based Experiments Ground-based Experiments • HIMAC-NIRS • ICCHIBAN 2nd, 4th, 6th • Peletron-UNAM (low-E p, He, C, O) • Loma Linda (proton ICCHIBAN) • NSRL-BNL Space-based Experiments • STS - several • Soyuz/ISS (MATROSHKA I & II) • Soyuz (MESSAGE; MOBILIZATION) • Soyuz/ISS (BRADOS) • Antarctica Balloon flight (TRACER) Multiple collaborators Slide 13 Summary of Major Properties graghs for Efficiency to LET (keV/΅m H2O). Labels for Al2O3C Luxel dosimetes, Al2O3C single crystal dosimeters (a) Al2O3:C single crystal dosimeters Integrated CW-OSL Initial CW-OSL intensity TL peak height (b) Al2O3:C LuxelTM dosimeters POSL Integrated CW-OSL Initial CW-OSL intensity (1) OSL from Al2O3shows sensitivity to HCP of LET > 10 keV/΅m (up to 290MeV/n Xe; 1047 keV/΅m) (2) Sensitivity & precision depend on method of OSL readout (3) Sensitivity & precision depend on material (chip, Luxel) Slide 14 Summary of Major Properties graphs for OSL normalized over time, luminescence signal normalized over Dose (Gy) and CS-OSL normalized over time (4) Sensitivity decrease with LET due to loss of sensitivity at high doses (5) OSL decay rate depends on (a) dose, (b) LET Slide 15 Summary of Major Properties (6) Possibility of LET information from OSL decay curves (a) Ratio of area to initial intensity (b) Ratio of decay constants (7) Possibility of LET information from emission spectra graph of possibility of LET information from emission spectra graph of possibility of LET information from OSL decay curves. Slide 16 OSL from Al2O3:C: emission bands POSL measurements graph of POSL measurements with OSL to Wavelength to transmittance (%) indicated Channel B (signal between laser pulses) Channel A (signal during laser pulses) Slide 17 CW-OSL from Al2O3:C: dose dependence graph of CS-OSL fignal (arb. units) to Dose (Gy) Slide 18 CW-OSL from Al2O3:C: LET dependence graph of LET dependence with S sub uv/S sub F-center to LET in water (keV/΅m) Slide 19 CW-OSL from Al2O3:C: relative efficiency graph for relative efficiency indicating n to LET in water (kdV/΅m) Closed symbols: UV Open symbols: F-center. Slide 20 Summary of Major Properties graphs for 100 mGy beta, 100 mGy He, 100 mGy C and 100 mGy Fe (8) Possibility of extracting dose due to low LET from dose due to high LET Slide 21 Risoe TL/OSL reader image of TL/OSL reader Slide 22 Experimental OSL readers images of portable POSL system and laboratory POSL system Slide 23 Experimental OSL readers image of OSL readers - InLightTM(Landauer Inc.), MicroStarTM(Landauer Inc.) Slide 24 Current OSL applications Personnel dosimetry of ionizing radiation (Landauer Inc.) (Technology licensed from OSU) 60,000 costumers (1.4 million individuals) Al2O3:C from Landauer Crystal Growth Division (Stillwater) image of pim and Al2O2:C growth from crystal images of dosimeters and LuxelTMbadge Slide 25 Future projects: The Citizens' Dosimeter image of New York City • Project underway at the Environmental Measurements Laboratory (Gladys Klemic -gladys.klemic@dhs.gov) • Credit card format dosimeter • Strategically placed card readers • Combine existing technology in new design Requirements • Sensitivity between 0.5mGy - 10 Gy • Readout in 3s • Signal loss <10% relative to previous readout Slide 26 Future projects: the Citizens' Dosimeter Objectives • Design and build a functioning prototype OSL reader (light source, light transducer, associated electronics) • Operational in a bench-top setting, but components chosen such that they could be incorporated into a rugged commerical version (that could be used in a sheltered outdoor environment). • Design the coupling between a prototype card and the reader • Design the prototype card Slide 27 Mars Dating Instrument Objectives • Design and build a functioning prototype TL/OSL reader for luminescence dating of martian surface sediments. • (light source, light transducer, associated electronics, radiation source) diagram of OSL chamber for single-sample lab use with labels fro photo detector, X-Ray tube, seal ring, blue LED KAPTON tape, heater assembly, chamber base, copper hot plate, chamber cover, infrared LED, photo detector Slide 28 Mars Dating Instrument image of Mars Dating instrument Slide 29 • Operational in a bench-top setting, chosen such that they could be rugged commercial version (sheltered outdoor environment). Design the coupling between the reader • Design the prototype Text Box: Future projects: The Citizens’ Dosimeter Future projects: Future projects: The CitizensThe Citizens’’ DosimeterDosimeter Slide 29 Space Dosimetry Next step • OSL personal dosimeter readout capability for long-duration missions (ISS, Moon, Mars) • Design and build a functioning prototype OSL reader for on-board use (light source, light transducer, associated electronics, software) • Design an astronaut personal dosimetry badge including capability for PNTD and TLD • Design interface to the reader Slide 30 Space Dosimetry Requirements • Sensitivity < 0.01 mGy • Days to years of accumulated dose (up to 3 year missions) • Fast and easy readout • Dosimeter – easy to wear, use, handle, read • Light-weight, low power, etc. Slide 31 Space Dosimetry Conclusions: • Fabrication of a small OSL reader will happen in the next few years due to the convergence of interests in homeland security, planetary exploration, luminescence dating, and space dosimetry • All elements for the reader are available. There is no critical obstacle: OSL readout is already realized, electronics is feasible. Slide 32 Thank you!