220 likes | 225 Views
This study investigates the origin of XMM unfocused and focused particle background. The working hypothesis suggests that the data is mostly sensitive to high-energy cosmic ray protons and radiation belts. Correlations between different datasets and simulations support this hypothesis. The study also explores the focused background using ACE EPAM data to analyze soft protons and their concentration power.
E N D
THE ORIGIN OF THE XMM UNFOCUSED AND FOCUSED PARTICLE BKG FABIO GASTALDELLO INAF-IASF MI & AREMBES-EXTRAS GROUP
PRIMARY DATASETS: M2 CLOSED DATA, M2 OUT FIELD OF VIEW DATA, RADIATION MONITOR DATA • WORKING HYPOTESIS: M2 DATA ARE MOSTLY SENSITIVE TO HIGH ENERGY (> 100 MeV) COSMIC RAY PROTONS, RADMON DATA (20 MeV) ARE SENSITIVE TO DIFFERENT COMPONENTS: COSMIC RAYS (MOST OF THE TIME), SEPS, RADIATION BELTS • SCREEN RADIATION MONITOR LIGHT CURVES TO EXCLUDE “FLARING PERIODS” (SEPS FROM SEPEM REFERENCE LIST • http://dev.sepem.oma.be/help/event_ref.html) XMM UNFOCUSED BKG
Two units based on silicon diodes, the LE and HE detectors. Files with count rates, in particular HE0 with p+ from 8 to 40 MeV (and e- from 1 to 1.75 MeV) RADIATION MONITOR
M2 closed count rate (amplified by 10e4) and mean • Altitude of orbits THE RM VIEW OF THE XMM ORBIT • HE0 count rates
RM AND OUTFOV DATA • All data (selection for good data) 86 Ms
RM AND OUTFOV DATA • Data without SEPs (79 Ms), i.e. 6 Ms of time in SEPs
RM AND SEP • Sometimes SEP time interval is not conservative
RM AND OUTFOV DATA • Correlation after “flare cleaning” of RM light curves (71.5 Ms)
RM AND OUTFOV DATA • Clear correlation with time
SAME FOR CHANDRA ACIS • ACIS-S3 12-15 keV rate (taken from C. Grant website)
OFOV AND MAGNETOSPHERE • No correlation with magnetospheric environment
CLEAR CORRELATIONS OF EPIC M2 DATASETS WHEN THEY ARE REPRESENTATIVE OF HIGH ENERGY PARTICLE BACKGROUND (CLOSED, OFOV) WITH RM DATA WHEN THEY ARE REPRESENTATIVE OF COSMIC RAY PROTONS (NO SEP, NO “BELTS”) AND THE CLEAR ANTI-CORRELATION WITH SOLAR CYCLE STRONGLY SUPPORT THE HYPOTESIS OF HIGH ENERGY COSMIC RAY PROTONS AS THE ULTIMATE SOURCE OF THIS TYPE OF BKG • GEANT4 SIMULATIONS PINTPOINTS SECONDARY ELECTRONS CAUSED BY PROTONS INTERACTIONS AS THE ELEMENTS OF THE UNFOCUSED PARTICLE BACKGROUND CONCLUSIONS FOR THE UNFOCUSED BKG
OBJECTIVE: COMPARISON OF XMM BKG WITH ENVIROMENTAL ESTIMATES OF SOFT PROTONS AND ESTIMATE XMM OPTICS CONCENTRATION POWER • PRIMARY DATASETS: M2 IN-OUT FIELD OF VIEW DATA, ACE (IN L1) SUPRATHERMAL PARTICLE DETECTORS DATA (EPAM LEMS30 AND LEMS120) TO INVESTIGATE SP IN THE RIGHT ENERGY RANGE • LEMS30 IS ORIENTED AT 30° WITH RESPECT TO THE SPIN AXIS OF THE SATELLITE (WITHIN 20° OF THE EARTH-SUN LINE) AND IT IS NOT CONNECTED TO EARTH’S BOW SHOCK -> IT IS NOT SENSITIVE TO UPSTREAM EVENTS XMM FOCUSED BKG
A LOOK AT THE ACE EPAM DATA To Sun in the case of ACE
A LOOK AT THE ACE EPAM DATA • TESSEIN+15
COMPARISON OF RATES LEMS120 • COMPARISON WITH P1’ RATES (100% OF AVAILABLE CROSS-CORRELATION DATA, 88.8 Ms)
COMPARISON OF RATES LEMS120 (SEPS) • SEP PERIODS ARE 6.6 Ms (7.4% of P1’ data), NO SEP PERIODS ARE 82.5 MS (93% of P1’ data)
WHEN XMM IS OUTSIDE THE BOW SHOCK • RELATIVELY LOW STATISTICS
INTERMEDIATE STAGE OF THE ANALYSIS, NO STRONG CONCLUSIONS YET BESIDES THE VARIETY OF ACCELERATION SITES WITHIN THE MAGNETOSPHERE OF SOFT PROTONS • INVESTIGATION OF SEPS AS THE EVENTS WHEN TO GAUGE XMM COCENTRATION POWER (BUT JUST SPARSE COVERAGE OF EPIC DATA DURING THEM) CONCLUSIONS FOR THE FOCUSED BKG