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Recent Observations of Space Radiation Characteristics in a Tissue- Equivalent Phantom onboard International Space Station by Liulin-5 Dosemetric Telescope J. Semkova 1, R. Koleva 1, S. Maltchev 1, N. Bankov 1, V. Benghin 2, I. Chernykh 2, V. Shurshakov 2, V. Petrov 2, S. Drobyshev 2 1 Space Research and Technologies Institute, Bulgarian Academy of Sciences, jsemkova@stil.bas.bg 2 Institute of Biomedical Problems, Russian Academy of Sciencesjsemkova@stil.bas.bg RAD 2012, Nis, Serbia, 24 28 April, 2012 Slide 2 Ionizing radiation is a main health concern to the astronauts in long duration space flights. Complex ISS radiation environment GCR, trapped radiation, SEP, and the secondary radiation produced in the shielding materials of the spacecraft and in human body. Very dangerous is high energy heavy ion component of GCR, with high LET and highly penetrating in human body, with a large potential for radiobiological damage. Dose characteristics in LEO depend also on the solar cycle phase, spacecraft orbit parameters, helio and geophysical parameters. To estimate the organ doses measurements in phantoms are conducted on ISS Matroshka and Matroshka R projects. MOTIVATION Slide 3 Radiation sources in the Earth environment GCRs-99% protons and He nuclei, 1% heavy ions, energies up to tens of GeV/n -permanent source of ionising radiation, isotropic. Protons IERB - hundreds of MeV, directionality; electrons OERB- hundreds of keV. SPE- hundreds of MeV. Slide 4 South Atlantic Anomaly A LEO spacecraft encounters the inner radiation belt protons in the region of South Atlantic Anomaly (SAA). Although only about 5% of ISS mission time is spent in the SAA, the astronauts may collect more than 50% of their total absorbed dose during this short time period (Apathy et al., 2007). SAA forming (Heynderickx, 2002) Dimensions of SAA at 500 km altitude [http://heasarc.gsfc.nasa.gov/docs/rosat/ gallery/misc_saad.html]http://heasarc.gsfc.nasa.gov/docs/rosat/ gallery/misc_saad.html Slide 5 Bulgarian space radiation dosimetric instruments and experiments (Dachev etal., 1989, 2006, 2009, 2009a,2010, Semkova et al., 2010, 2011) Bulgarian space radiation dosimetric instruments and experiments (Dachev etal., 1989, 2006, 2009, 2009a, 2010, Semkova et al., 2010, 2011) 1.Liulin- MIR space station, 1988 1995 2.Radius MD1/2 on Mars-96; 3.Liulin-MDU1, June 14, 2000, ESA balloon flight up to 33 km over Gap, France; 4.Liulin-MDU5, more than 10000 hours from 2001 till 2009 on Czech airlines aircrafts; 5.Liulin-094, May-August 2001, ESA-NASA exp. on the International space station (ISS); 6.2 Liulin-MDU, June 2001, NASA ER-2 flights at 20 km altitude in USA; 7.R3D-B1, October 2002, ESA Foton M1 satellite unsuccessful launch; 8.R3D-B2, 1-12 2005, ESA Foton M2 satellite; 9.3 Liulin-MDU, June 11, 2005, NASA balloon flight up to 40 km over New Mexico, USA; 10.Liulin-ISS, ROSCOSMOS, launched to ISS in September 2005 (active now); 11.Liulin-6R, since October 2005 working in Internet (active now); 12.Liulin-Moussala, since June 2006 working in Internet (active now); 13.Liulin-5, ROSCOSMOS, since June 28, 2007 working at ISS (active now); 14.R3D-B3, September 14-26 2007, ESA Foton M3 satellite; 15.Liulin-6S, since October 2007 working at Jungfrau peak in Internet (active now); 16.Liulin-R, January 31, 2008, ESA rocket experiment up to 380 km from Norway; 17.R3D, worked at ESA Columbus module at ISS between 17/02/2008 and 01/09/2009; 18.RADOM, worked at Indian Chandrayyan-1 satellite around Moon between 22/10/2008 and 29/08/2009; 19.R3DR, worked at ESA EXPOSE-R facility on Russian Zvezda module of ISS between March 2008 and January 2011. 20.Liulin-Phobos launched on 9 November 2011 on Phobos-Grunt interplanetary station. Slide 6 Since 2005 Bulgarian scientists participate with 15 instruments in the scientific programs of: 4 manned space flights (4 instr.) 1 at ESA Columbus and 3 at the Russian segment of ISS 1 Moon spacecraft (1 instr.) Chandrayaan-1 2 spacecrafts (3 instr.) - Foton M2/3 2 HotPay rockets (2 instr.), 1 balloon (1 instr.), flight and many airplane flights (4 instr.) Rocket and balloon instruments Liulin-R Flown on HotPay 2 Rocket in 2008 Liulin-J Flown on NASA Balloon in 2005 Aircraftinstruments Liulin- type flown for more than 6000 hours fn CSA aircraft Slide 7 Spherical Tissue Equivalent Phantom and Liulin-5 Size: 370x370x390 mm; mass: 32 kg (Shurshakov, V. A, et al., 2006) Radiation detectors number of passive detectors and Liulin-5 charged paricle telescope. Liulin-5 detector module is placed in a radial channel. Aim of the experiment to measure the the time resolved depth distribution of the cosmic radiation doses in the phantom. Slide 8 LIULIN-5 in the Phantom in Piers-1 module of ISS activated 28 June 2007. Spherical Phantom LIulin -5 in the Spherical Phantom on ISS Detector module Phantom Slide 9 Block - diagram of Liulin - 5 connections in the phantom Slide 10 Goals Liulin-5 measures simultaneously at 3 depths of the radial channel of the spherical phantom: Energy Deposition Spectra, Dose Rate & Particle flux - then Absorbed Dose D. Measurement of the Linear Energy Transfer (LET) spectra in silicon then assessment of LET(H 2 O), Q=f(LET), given in ICRP-60 and Dose Equivalent H; H=DxQave. Slide 11 Quality factor Slide 12 RESULTS Dose and flux distribution in the radial channel of the phantom. LET spectra. Dosemetric quantities from GCR and trapped protons. Slide 13 Dose rate along the ISS trajectory Dose rates distribution at 60 mm depth (16.03- 04.09. 2009), D2 760 Gy/h. Max doses - at L ~ 1.36, ~ 0.2 Gs. Slide 14 Flux at the centre of the phantom along the ISS trajectory At L values 1.1-1.8 both GCR and trapped protons contribute to the measured flux. Maximum fluxes of 51.8 part/cm 2 s are registered from the trapped protons in SAA at L ~ 1.27. Minima values of about 0.12 part/cm 2 s were recorded at L~1 from GCR. At L 4 the particle flux from GCR was up to 2.1 part/cm 2 s. Slide 15 Absorbed depth-dose distribution and contribution of GCR and trapped protons to the total doses Typical Slide 16 Data for 24.10-01.11.2008. From top to bottom: 1) LET spectra averaged over the whole interval; 2) GCR and secondary radiation LET spectra averaged outside SAA; 3) LET spectra averaged over measurements in SAA - trapped protons mainly. Due to HZE particles in LET spectra of GCR, the GCR Q is higher than that of the trapped protons. LET spectra and Qav Slide 17 Absorbed average daily dose at the depth of 40 mm (BFO), Qav and averaged daily dose equivalents from particles of 0.65 LET (H 2 O) Absorbed average daily dose at the depth of 40 mm (BFO), Qav and averaged daily dose equivalents from particles of 0.65 LET (H 2 O) Date Date Dose [Gy/day] Qav Dose equivalent [Sv/day] GCRSAATotalGCRSAATotalGCRSAATotal 3-10.07. 07 79.8117.21975.961.323.2475.7154.7 630.4 17-24.11.0781.4105.2177.65.61,333.35455.9139,9595.8 23-28.02.0883.7126.5210.26.21.383.31521.2174.6 695.8 20-27.04.08 83.9 98181.95.591.33.28469.2127.4596.6 24.10- 1.11.08 86.8111.9198.74.741.352.83411.2151.1 562.3 23-28.02.098895.7183.75.911.343.53520.1128.2648.3 Slide 18 CONCLUSION (1) The averaged absorbed daily doses at the depths corresponding to BFO depths are 180 -220 Gy/day. The contribution of the trapped protons is about 50-60% of the total absorbed doses and the rest of the dose is from the GCR. Due to the self-shielding of the phantom against trapped protons the absorbed doses at 165 mm depth typically decrease by a factor of 1.6-1.8 compared to the doses at 40 mm depth. A detailed mapping of the particle flux and dose rate distribution along the ISS orbit is done. Slide 19 CONCLUSION (2) Typically Qav from 2007 to 2009 is 2.7-3.5, the average dose equivalent at the depth of BFO is 560-700 SV/day. At the minimum of the 23rd solar cycle the dose equivalent of GCR and their secondary particles represents 70% of total dose equivalent at the depths of BFO. Liulin-5 experiment continues in 2012-2015 aboard ISS to obtain data for solar activity maximum. Slide 20 ACKNOWLEDGEMENTS Agreement between RAS and BAS on space research and grant DID-02/8 from the Bulgarian Science Fund. NIRS - Japan. RKK Energia and cosmonauts O. Kotov, Y. Malenchenko, O. Kononenko and Y. Lonchakov for the operation of Liulin - 5 aboard ISS. Slide 21 REFERENCES Chernykh, Iet al., ISS attitude influence on the dose rate measured with Liulin-5 instrument, Workshop on Radiation Measurements on ISS, Krakow, Poland, 8-10 September 2008, http://www.wrmiss.org/workshops/thirteenth/Chernykh.pdf. http://www.wrmiss.org/workshops/thirteenth/Chernykh.pdf Dachev, Ts.et al, Space radiation dosimetry with active detections for the scientific program of the second Bulgarian cosmonaut on board the MIR space station, Adv. Space Res., 9, 10, 247, 1989. Dachev, et al. Observations of the SAA radiation distribution by Liulin-E094 instrument on ISS, Adv. Space Res. 37 (9), 16721677, 2006 Dachev, Tset al., Relativistic electrons high doses at International Space Station and Foton M2/M3 satellites, Adv. Space Res. 44, 14331440, 2009. Dachev, Ts.P., Characterization of near Earth radiation environment by Liulin type instruments, Adv. Space Res., 1441-1449, 2009a. doi:10.1016/j.asr.2009.08.007doi:10.1016/j.asr.2009.08.007 Dachev Ts. et al, Analysis of the GCR Dose Rate Increase onboard Spacecraft and Aircraft in the Declining Phase of the 23rd Solar Cycle, Fundamental Space Research, Supplement of Comptes Rend. Acad. Bulg. Sci., ISBN 987- 954-322-409-8, 142-146, 2010. http://www.stil.bas.bg/FSR2009/pap139.pdfhttp://www.stil.bas.bg/FSR2009/pap139.pdf Dachev, Ts. et al, An overview of RADOM results for Earth and Moon Radiation Environment on Chandrayyan-1 Satellite, Adv. Space Res., 48, 5, 779-791, 2011. doi: 10.1016/j.asr.2011.05.00910.1016/j.asr.2011.05.009 ICRP Report No. 60, Pergamon Press, Oxford, 1991. Heynderickx, D., Magnetic field models, SPENVIS user workshop, http://space- env.esa.int/EMA_Events/SPENVIS_WS2002/index.htmlhttp://space- env.esa.int/EMA_Events/SPENVIS_WS2002/index.html Semkova, J., et al., Radiation measurements inside a human phantom aboard the International Space Station using Liulin-5 charged particle telescope, Advances in space research, 45, Issue 7, (2010), 858-865, doi:10.1016/j.asr.2009.08.027 doi:10.1016/j.asr.2009.08.027 Semkova J et al., Depth Apathy I., et al. TL measurements on board the Russian segment of the ISS by the Pille system during Expedition -8, -9 and -10. Acta Astronaut., 60, 322-328, 2007. dose measurements with the Liulin-5 experiment inside the spherical phantom of the Matroshka-R project onboard the International Space Station, Advances in Space Research 2012, http://dx.doi.org/10.1016/j.asr.2011.10.005 http://dx.doi.org/10.1016/j.asr.2011.10.005 Shurshakov, V. A, et al. Measurements of the absorbed dose distribution in the spherical tissue equivalent phantom in MATROSHKA-R space experiment, 11th WRMISS, United Kingdom, Oxford, 2006. http://www.wrmiss.org/workshops/eleventh http://www.wrmiss.org/workshops/eleventh Slide 22