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Low energy payload of Solar X-ray Spectrometer (SOXS) mission :

Low energy payload of Solar X-ray Spectrometer (SOXS) mission : i nstrument description and first results. Dr . Tomasz Mrozek Astronomical Institute University of Wrocław. Solar X-ray Spectrometer ( SoXS ). First Indian space-borne solar physics experiment Launched on 8 May 2003 by

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Low energy payload of Solar X-ray Spectrometer (SOXS) mission :

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  1. Low energy payload of Solar X-ray Spectrometer (SOXS) mission: instrument description and first results Dr. Tomasz Mrozek AstronomicalInstitute University of Wrocław

  2. SolarX-raySpectrometer (SoXS) First Indian space-bornesolar physicsexperiment Launched on 8 May 2003 by GSLV-D2 rocket „Payload of opportunity”onboardthe geostationarysatellite GSAT-2 Itiscomposed of two independent modules: - SOXS Low-energyDetector (SLD) - SOXS High-energy Detector (SHD) T. MrozekWrocław 31.05.07 First SphinXWorkshop

  3. The SLD module Consists of foursubsystems: - Low Energy Detector (SLED) - Sun TrackingMechanism (SSTM) - Low Energy Processing Electronics (SLE) - Common Electronics (SCE) T. MrozekWrocław 31.05.07 First SphinXWorkshop

  4. The SLED package • SOXS Low Energy Detectorpackage: • two solid state detectors – CZT and Si PIN • (hermetic TO-8 package • from AMPTEK) • collimators – aluminium nickeltubes • filters – Be windows plus aluminium • and kaptonpolyamide to cut • photonsbelow 4 keV T. MrozekWrocław 31.05.07 First SphinXWorkshop

  5. The SLED package T. MrozekWrocław 31.05.07 First SphinXWorkshop

  6. The SSTM package SOXS is a payload of opportunity mounted on theanti-earthview side of thespacecraft. Sun trackingmechanismisneeded sincethe FOV is limited Ithave single drive module whichenablestrackinginboth rightascension and declination Observationsarepossibleeach daybetween 3:40 UT and 6:40 UT T. MrozekWrocław 31.05.07 First SphinXWorkshop

  7. In-orbit calibration Onboardradioactivesource : Cd109emitting lines at 22.2 keV and 25 keV Thermoelectriccooler (TEC) ON and OFF Temperature of thedetectors: -15 and -25◦C Si PIN shows 22.2 keVlineirrespective of TEC ON or OFF condition The CZT shows a shift of 14 channels as the TEC is ON Thisanomalyreducesthedynamicalrange of CZT. Itisnow 4-56 keVinstead of 4-60 keV T. MrozekWrocław 31.05.07 First SphinXWorkshop

  8. SLD operatingmodes SurveyMode– observespreflarebackgroundusedfurther for determinigthe threshold for flaretrigger. Usuallythethresholdisequal to 5times measuredbackgroundintwo energy windows: 10-20 keV (Si) and 20-30 keV (CZT) SearchMode– observationsinthese energy windowsaremadewith 100 ms cadence but arerecordedevery 1 s. T. MrozekWrocław 31.05.07 First SphinXWorkshop

  9. SLD operatingmodes FlareMode – isturned on when five consecutive 100 msobservationsinany of energy windowexceedsthethreshold. Thismodelasts 287.5 s. Observationsarerecordedwith 100 mscadence. QuietMode– turned on afterflaremode. Lasts 2274 s. Observationsaremade withcadence 1 s (temporal data) and 3 s (spectral data). These limitationsaredue to the limited onboardmemory and telemetry rate. T. MrozekWrocław 31.05.07 First SphinXWorkshop

  10. First light First light was obtained on 08 jun 2003 Bothdetectorsareverysensitive to observeevenveryweakflares. T. MrozekWrocław 31.05.07 First SphinXWorkshop

  11. RHESSI lightcurves T. MrozekWrocław 31.05.07 First SphinXWorkshop

  12. Energy resolution Si CZT Gaussianfits to observed count spectra Si revealssub-keV (.7-.8 keV) energy resolution CZT have energy resolution of 1.7 keV(at 6.7 keV) and 2 keV(at 22.2 keV) Thesevaluesareinagreement withpre-flarecalibrations T. MrozekWrocław 31.05.07 First SphinXWorkshop

  13. Otherissues Instrumentalresponseis diagonal (no Compton scattering etc.) Preflarebackground was estimated to be <3000 cts s-1. In-situ observationsshows thatitsignificantlyloweri.e. <1500 cts s-1 Developed electronics rejectspileup problem for moderatecountrates (<20 000 cts s-1). For high countrateeventsthereis software techniquedevelopedwhichhelpsavoid the problem of pileup. T. MrozekWrocław 31.05.07 First SphinXWorkshop

  14. Photon spectra T. MrozekWrocław 31.05.07 First SphinXWorkshop

  15. Relationbetweentheequivalent width of Fe line and temperature Jain 2006, J. Astrophys. Astr. 27, 175 Phillips 2004, ApJ 605, 921 T. MrozekWrocław 31.05.07 First SphinXWorkshop

  16. Relationbetweentheequivalent width and temperature Phillips 2004, ApJ 605, 921 T. MrozekWrocław 31.05.07 First SphinXWorkshop

  17. Conclusions PIN detectorworksfineinthegeostationary orbit Senstitivityisenough for measuringflux of weakflares. Temporal and energy resolutionsareconsistentwithexpectations Severalissuessuggestingproblemswithabsolutecalibration. Photon sepctraseem to be overestimated of an order of magnitude T. MrozekWrocław 31.05.07Wrocław First SphinXWorkshop

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