New results for Radiation Effects on the Human Health Obtained during the COST-724 Action F. Spurný a, Ts. Dachev b, a Nuclear Physics Institute, Czech Academy of Sciences, Prague, Na Truhlarce 39/64, Praha 8, Czech Republic, Phone: +420 b Solar-Terrestrial Influences Laboratory, Bulgarian Academy of Sciences (BAS), Acad. Georgi Bonchev St. Block 3, 1113 Sofia, Bulgaria, Tel.:

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Table of content Specificity of onboard spacecraft (Space) radiation fields from the point of view of radiation risk Some of topics treated during COST 724:  Investigation of earth radiation environment on International Space Station on Foton M2 satellite and on Aircraft  Onboard spacecraft neutron contribution as estimated on the base of the comparison of results measured with MDU-Liulin equipment  Further analysis of long-term measurements onboard of Czech Airlines Aircraft

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Specificity of onboard spacecraft (Space) radiation fields – compared to Earth 1.Exposure level much higher: ~ 1 mSv (Earth) to ~ several 100 mSv/year, nevertheless not too excessively; still low-dose region with very few data available on radiation risk 2. However - solar flares can appear – then up to orders higher in open Space – accidental exposure 3. Much higher contribution of radiation with high linear energy transfer (LET) – also only few data available 4. For aircraft crew exposure – much more females concerned

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Radiation Protection Justification - final effect of the activity leading to an exposure would be positive Optimization - to keep the exposure as low as achievable Limitation -not to exceed limits

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Exposure limits in Space and/or on the Earth Effective (equivalent) dose limits, Sv

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Tasks to be treated To improve the conditions for safe prolongation of human space activities needs to diminish uncertainties related to the estimation of the risk, both biological factors as physical knowledge, both dosimetric as microdosimetric, For that, it is necessary:  to accumulate data on actual level of exposure in Space at different conditions and situations (flight altitude and other parameters, solar activity, shield thickness, galactic cosmic rays vs. solar component (SAA)), etc., not only quantitative but also qualitative data (microdosimetry)  to search for correlation between Space and close-to- Earth exposure levels

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Activities WP2400/WG2 of COST 724 Longer term monitoring and measurements onboard ISS and other space vehicles Studies during shorter space missions with more complex sets of instruments Long term monitoring as well as punctual measurements onboard aircraft (Czech Airlines) Search for correlation of these data sets considering actual situation characterising “Space Weather” Three examples follow

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Simultaneous Investigation of Galactic Cosmic Rays on Aircrafts, Foton M2 satellite and on International Space Station

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Distribution of Foton M2 earth radiation environment against the L value GCR

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May % increase of the doses on aircraft altitudes in 2005 are observed because of lower solar activity 820 MV 594 MV

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May The doses and fluxes obtained with the Foton M2 satellite confirms the westward drift of the SAA anomaly with about 0.28 degree per year

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Onboard spacecraft neutron contribution as estimated on the base of the comparison of results measured with MDU-Liulin equipment Neutron contribution to the spacecraft crew exposure could represent up to several tens % of the total value of the dose equivalent. The determination of this contribution represents rather complex and difficult task, both through experimental as theoretical estimation; up to now great differences in estimations An attempt to appreciate the neutron contribution onboard International Space Station and Foton capsule using the data measured by means of a Si- diode based energy deposition spectrometer, and on their comparison with on-Earth and onboard aircraft measured data

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Spacecraft and aircraft flight conditions International Space Station – May 2001, inclination 51.6 o, altitudes between 360 and 420 km; shield about 20 g.cm -2, total D(Si) ~ 6 mGy Foton M2 capsule – May 2005, inclination 62.6 o, altitudes between 260 and 304 km; shield ~ 2 g.cm -2, total D(Si) ~ 0.6 mGy Aircraft – A – since 22/03/01, 12 two month’s runs, more than 1100 flights, mostly over the North Atlantic, about 5000 hours at flight altitude, total D(Si) ~ 9.3 mGy; > spectra

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Comparison of energy deposition spectra - 3

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Spacecraft board interpretation procedure 1. GCR:  Supposed that: E dep bellow ~ 1 MeV – low LET component E dep above ~ 1 MeV composed of:  neutron component with similar spectra as onboard aircraft,  and contribution of HECP of GCR  Interpreted as: Low LET component: D(Si)→D(tissue)→”H*(10)”; Neutron component: as onboard aircraft; GCR component: D(Si)→D(tissue)x5=“H*(10)”;  To get as good statistical reliability as possible - all aircraft spectra summed up and regressed for E dep above ~ 1 MeV 2. SAA:  Supposed that all events are due to protons of SAA  Interpretation: D(Si)→D(tissue), and D(tissue) x QF average calculated from energy distribution spectra (~1.3) = “H*(10)”;

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Comparison of CERF, aircraft, and spacecraft calculated spectra

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Regressed aircraft energy distribution spectrum-comparison with spacecrafts

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Daily values of dose quantities onboard space vehicles

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Further analysis of long-term measurements onboard of Czech Airlines Aircraft MDU was placed on board of aircraft (A ) several times in years 2001, 2002, 2005 and The database contains more than 41,000 records and each one contains information on: date and time, direction of flight, geographic coordinates, altitude, vertical cut-off rigidity, Apatity neutron monitor records, and dosimetric characteristics based on measurements with MDU and calculated by codes CARI-6 and EPCARD v3.2.

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Statistics of database parameters

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Results of analysis - 1 Cut-off rigidity dependence of dosimetric characteristics Altitude dependence of dosimetric characteristics

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Results of analysis - 2 Ratio of non-neutron and neutron component of H*(10) measured with MDU and calculated with EPCARD v3.2 as function of altitude (rigidity is from interval 1÷3 GV). Ratio of non-neutron and neutron component of H app (MDU) and H*(10)(EPCARD) as function of rigidity (altitude 35,000 feet).

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Results of analysis - 3 Geomagnetic position dependence of E dep distribution.

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Conclusions - aircraft Rates of dosimetric characteristics increase with ascending altitude, decrease with ascending rigidity; Happ(MDU) and E(CARI) values correlate well; Ratio of non-neutron and neutron components does not depend on the altitude but depends on the rigidity; neutron contribution is dominant below 7 GV.

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May FD 09/05 - comparison of MDU and Oulu neutron monitor data; corrected for the difference H app (MDU)/E(CARI)

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May GLE 68 – Effective dose rate estimation Maximum of GLE intensity at 40,000 ft

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May General conclusions During COST 724 (WG2, WP2400) activities: Methodology improved and new results on actual level of exposure at different conditions and situations (flight altitude and other parameters, solar activity, shield thickness, galactic cosmic rays vs. solar component (SAA), etc., not only quantitative but also qualitative data (microdosimetry) acquired Several examples of correlation between Space and close-to-Earth exposure levels studied These results would help to diminish uncertainties related to the estimation of the risk based on physical knowledge, both dosimetric as microdosimetric.

Acknowledgements Colleagues responsible for preparation realization and exposure of detectors onboard of space vehicles, and aircraft, mainly: V.A. Shurshakov, B. Kolář, J. Starý Colleagues from STIL BAS, and NPI AS CR, mainly : B. Tomov, P. Dimitrov, Y. Matviichuk, O. Ploc

Spurny & Dachev COST-724 MCM meeting, Sofia, 22 May Thank you for your attention