Overview of observational methods and instruments: spectrographs Sergei Shestov
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Outline Scientific importance of spectroscopic observations Solar spectra Methods & assumptions of spectroscopic analysis Layout of a generic spectrograph Types of spectrographs: Slit spectrograph Slitless spectrographs Crystal spectrographs Photometers Solid state spectrographs Literature 7 Feb 2018 SIDC seminar: spectrographs 3
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Some facts about spectroscopic observations Bohr s model of the Hydrogen atom (1913); Hubble s law (1927, based on V. Splipher redshifts); Solar corona: determination of temperature (Edlen, 1942), chemical composition; Atomic physics: atomic structure (diel. satellites), precise energy levels (the IRON project) 7 Feb 2018 SIDC seminar: spectrographs 5
Solar corona spectrum Blackbody T=5762 K in whitelight (thermodynamic eq.); Charged ions emit spectral lines and continuum as a result of excitation; Bremsstrahlung emission of electrons; 7 Feb 2018 SIDC seminar: spectrographs 6
Bohr atom model, Hlike atoms H Z=1 ~ 1215 Å He II Z=2 ~ 304 Å Mg XII Z=12 ~ 8.42 Å Fe XXVI Z=26 ~ 1.80 Å Fe IX 170.07 Å: 3p 6 1 S 0 < 3p 5 3d 1 P 1 ; Fe XII 195.12 Å: 3s 2 3p 3 4 S 3/2 < 3s 2 3p 2 (3p) 3d 4 P 5/2 7 Feb 2018 SIDC seminar: spectrographs 7
Methods of spectroscopic analysis j I hν ~ N X,m j N X,m A ji g ~ N X,m N e ~ Ab X f(t, n e ) N H N e T, n e hν I hν ~Ab X f T, n e A ji N H N e Intensities of individual lines distribution of T, n e ; Spectral line shape T, presence of flows; 7 Feb 2018 SIDC seminar: spectrographs 8
Necessary simplifications I hν ~ Ab X f T, n e A ji N H N e Optically thin Ionization equilibria Electron excitation are more frequent T, n e hν 7 Feb 2018 SIDC seminar: spectrographs 9
Necessary simplifications H α spectral line I hν ~ Ab X f T, n e A ji N H N e Optically thin Ionization equilibria Electron excitation are more frequent T, n e hν 7 Feb 2018 SIDC seminar: spectrographs 10
Generic layout of a spectrograph Entrance slit Collimator Dispersive element (prism) Objective Detector 7 Feb 2018 SIDC seminar: spectrographs 11
Types of spectrograph Diffraction grating based Slit Slitless Photometers Crystal based Solid state based down to 30 Å; 12500 Å; 0.5 30 Å; Si 0.515 kev (0.830 Å); Ge 4 kev17 MeV; EIS/Hinode; CDS, SUMER (SOHO); SERTS; VAULT; IRIS Skylab S082A; SPIRIT/CORONASF; EVE/SDO; Lyra/PROBA2; GOES SXR; RESIK, DIOGENESS, Mg XII (CORONASF); BCS, FCS (SMM); BCS/Yohkoh; SphinX/CORONASPHOTON; RHESSI; SOXT; 7 Feb 2018 SIDC seminar: spectrographs 12
Slit spectrograph EUV & UV spectral range 7 Feb 2018 SIDC seminar: spectrographs 13
IRIS UV spectrograph 7 Feb 2018 SIDC seminar: spectrographs 14
SUMER/SOHO CDS/SOHO EIS/Hinode IRIS SERTS SPICE/Sol.Orb. 3901610 Å 150800 Å 170210, 250290 Å 13301360, 13901410, 27802850 Å 170225, 235450 Å 704790, 9701040 Å FUV spectra from IRIS (Tian et al. 2015) Monochromatic image Fe XII 195.12 Å from EIS/Hinode Doppler shift map 7 Feb 2018 SIDC seminar: spectrographs 15
Pros & Cons slit spectrographs High spectral resolution & spatial resolution in direction; Spectra of small regions covered by the slit or slot; Impossible to get simultaneous spectra of the whole Sun scanning; Large amount of optics small sensitivity; Save the whales photons! 7 Feb 2018 SIDC seminar: spectrographs 16
Spectroheliograph EUV & UV spectral range 7 Feb 2018 SIDC seminar: spectrographs 17
Spectroheliograph EUV & UV spectral range 7 Feb 2018 SIDC seminar: spectrographs 18
Spectroheliograph EUV & UV spectral range 7 Feb 2018 SIDC seminar: spectrographs 19
S082A spectroheliograph on Skylab 170630 A; Concave grating; Photographic film; 7 Feb 2018 SIDC seminar: spectrographs 20
SPIRIT EUV spectoheliograph on CORONASF 176207, 280335 A; Plane grating, grazing incidence; Multilayer mirror & CCDbased detector 7 Feb 2018 SIDC seminar: spectrographs 21
Pros & Cons spectroheliographs FullSun spectral images; Higher sensitivity? Possibility for high corona observations; Lower spatial resolution WRT slit spectrographs; Monochromatic images are overlapping overlapograms; Difficult to analyze data; Future: COSIE for the ISS CfA, for the high corona observations KORTES for the ISS LPI, studying of flaring plasma 7 Feb 2018 SIDC seminar: spectrographs 22
EUV slit spectrograph with no imaging EVE/SDO 7 Feb 2018 SIDC seminar: spectrographs 23
EUV slit spectrograph with no imaging EVE/SDO 7 Feb 2018 SIDC seminar: spectrographs 24
Pros & Cons No spatial resolution average spectrum of the Sun; Very wide spectral bandwidth; High temporal resolution; High sensitivity; 7 Feb 2018 SIDC seminar: spectrographs 25
Crystal spectrograph Low λ impossible (almost) to use diffraction gratings; Crystals BraggWulf law: nλ = 2d sin λ 7 Feb 2018 SIDC seminar: spectrographs 26
Crystal spectrograph Low λ Bent crystal impossible (almost) to use diffraction gratings; Crystals BraggWulf law: nλ = 2d sin λ Mission Instrument Spectral range, A Crystal Solar Maximum Mission BCS 1.7691.796 Ge 422 spectrometer FCS 3.1653.231 Ge 220 CORONASF DIOGENESS 3.143.39 Quartz 101 4.985.37 ADP 6.116.73 Beryl 2.963.21 Quartz 1010 RESIK 3.403.80 Si 111 4.354.86 Quartz 1010 Yohkoh BCS 1.761.80 Ge 222 Hinotori Intercosmos Bragg crustal spectrometer 1.831.89 Ge 222 5.025.11 Ge 111 P78 7 Feb 2018 SIDC seminar: spectrographs 27
Flat and Bentcrystal spectrographs BCS/Yohkoh (19912001) 1.75.1 Å 7 Feb 2018 SIDC seminar: spectrographs 28
RESIK flare spectra RESIK/CORONASF (20012005) 3.5 6.1 Å 7 Feb 2018 SIDC seminar: spectrographs 29
RESIK flare spectra RESIK/CORONASF (20012005) 3.5 6.1 Å Chifor et al. 2007; C5.8 flare 22 Feb 2003 7 Feb 2018 SIDC seminar: spectrographs 30
Mg XII spectroheliograph 8.42 Å Crystal quartz mirror [10 1 0] Detector CCD 2d=8.501 > BraggWulf > λ=8.42 Å 7 Feb 2018 SIDC seminar: spectrographs 31
Emissivity Mg XII 8.42 Å Mg XII spectroheliograph 8.42 Å 7 Feb 2018 SIDC seminar: spectrographs 32
Pros & Cons crystal spectrographs Soft Xray wavelength; Limited set of crystals available; Imaging capabilities are limited; Really see hot plasma; Future: ChemiX for the InterhelioProbe SRC, Wroclaw SolPex for the ISS SRC&LPI MaGIXS from MSFC 7 Feb 2018 SIDC seminar: spectrographs 33
MaGIXS spectrograph for Soft Xray Telescope Slit Collimator Diffraction grating CCD detector Slit soft Xray spectrograph; 6.024.0 Å spectral range (0.52.0 kev); Grazing incidence diffraction grating; Wolter type I telescope; Grazing incidence collimator; CCD detector; MaGIXS Marshall Grazing Incidence Xray Spectrometer 7 Feb 2018 SIDC seminar: spectrographs 34
Photometers Lyra/PROBA2 GOES SXR detectors 12001230 Å 19002200 Å 1800 Å 1200 Å; 0.54 Å 18 Å; Detector Filters Solar flux 7 Feb 2018 SIDC seminar: spectrographs 35
GOES SXR detectors Series of satellites since 1974; Two ion chamber based SXR detectors; Different response of two detectors > Diagnostics of plasma T, EM (White et al. 2005) 7 Feb 2018 SIDC seminar: spectrographs 36
Pros & Cons photometers Relatively simple to build; Relatively difficult to interpret data, due to registering of average signal in some passband; 7 Feb 2018 SIDC seminar: spectrographs 37
Solid state spectrographs Due to absorption in semiconductor a photon creates charge in the valence zone; For Si 3.6 ev per eh pair, e.g. 8.42 Å = 1.47 kev > 410 e SphinX/CORONASPHOTON Si photodiodes, 0.515 kev RHESSI Ge detectors, 4320 kev; SOXT 425 kev Si, 456 CdZnTe; STIX/Sol.Orb. CdTe detectors, 4150 kev 7 Feb 2018 SIDC seminar: spectrographs 38
SphinX soft Xray spectrometer SphinX/CORONASPHOTON XRT/Hinode TESIS/CORONASPHOTON 7 Feb 2018 SIDC seminar: spectrographs 39
RHESSI T~30 MK T~10 MK Bremsstrahlung from energetic electrons Decay of pions 7 Feb 2018 SIDC seminar: spectrographs 40
Pros & Cons solid state spectorgraphs Possibility to go to higher energies; High cadence; No spatial resolution? Low spectral resolution; 7 Feb 2018 SIDC seminar: spectrographs 41
Thank you! 7 Feb 2018 SIDC seminar: spectrographs 42
Literature K. Phillips, U. Feldman, E. Landi Ultraviolet and Xray Spectroscopy of the Solar Atmosphere Doschek, G. A., & Feldman, U. (2010). The solar UV xray spectrum from 1.5 to 2000 Å CHIANTI atomic database documentation M. J. Aschwanden, Physics of the Solar Corona. An Introduction Chapter 2 Mason, H. E., & Monsignori Fossi, B. C. (1994). Spectroscopic diagnostics in the VUV for solar and stellar plasmas 7 Feb 2018 SIDC seminar: spectrographs 43
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AIA channels and composites; HMIB 7 Feb 2018 SIDC seminar: spectrographs 48
AIA thermal responses 7 Feb 2018 SIDC seminar: spectrographs 49
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