LYRA Flight Model PFM in the synchrotron calibration
LYRA Flight Model (PFM) in the synchrotron calibration facility in PTB, Berlin
LYRA SCSL 1 st meeting, June 20 -22, 2006 Introductory talk outline n n Introduction to the LYRA instrument Introduction to LYRA Science Information about calibration Possible contributions of the SCSL team
General introduction to the instrument n http: //lyra. oma. be
LYRA instrument consortium : a Belgian-Swiss team with international partners
LYRA highlights n 4 channels covering a wide temperature range 1. 2. 3. 4. 200 -220 nm Herzberg continuum range (interference filter) Lyman-alpha (121. 6 nm, interference filter) Aluminium filter channel (17 -70 nm) incl. He II at 30. 4 nm Zirconium filter XUV channel (1 -20 nm) • n n rejects strongly He II Traceable to radiometric standards n Calibration campaigns at PTB Bessy synchrotron In-flight stability n Rad-hard, not-cooled, oxide-less diamond UV sensors n 2 different LEDs per detector n Redundancy (3 units) High cadence (up to 100 Hz) Quasi-continuous acquisition during mission lifetime
LYRA : 3 units, 12 detectors, 24 LEDs… Z Y X
Dec 2005 tbc April 2006 tbc
Inside LYRA 315. 0 x 92. 5 x 222. 0 mm ~A 4 size 2. 85 W (<5 W required) 3. 533 kg t ng e l e 1 u = t i n av w 4 h hc a els n n 3 units 12 detectors 24 LEDs …
One of the 3 LYRA units
Head geometry 27. 75 1. 03 0. 5 (the Sun is 0. 5°) The 2. 06° FOV must mend internal, external misalignment and jitter issues
LYRA Detectors n Pi. N and photoconductor (PC) diamond UV sensors n Solar blindness (5. 45 e. V, less filters, more signal) n Radiation hardness n Low thermal noise (No need for cooling) n n n Chemical inertness Mechanical stability Highest thermal conductivity n AXUV-20 Si diodes n Good heritage Merit of diamond UV sensor
PIN and MSM
Solar blind diamond detectors Ø 5 mm Ti/Pt/Au contacts – diamond MSM structures 5 V diamond Pi. N sensor IMOMEC, Belgium with the collaboration of the National Institute for Materials Science (NIMS), Japan. MSM structures and Pi. N junctions, depending on the LYRA channel.
Channel configuration AXUV 20 D LYRA_Assembly_20050629. xls
LYRA science
Temporal coverage of UV irradiance measurements 200 -220 nm (Herzberg continuum) 115 -125 nm (Lyman alpha) 17 -30 nm (EUV, incl. He. II) 1 -20 nm (soft X-rays) Woods et al 2005 LYRA
Cadence of UV irradiance measurements
Solar UV radiometry n Irradiance = f( passband, time) n Measurement attributes: n Accuracy, precision, SNR n n Needs for on-ground and in-flight calibrations, stability, robustness, rad-hardness temporal coverage n Science fields n Solar Physics n Terrestrial aeronomy n Heliospheric and planetary research n Space Weather
Solar physics n LYRA provides cadence and temporal coverage but no spectral resolution and non-imaging To recover the solar spectrum and to cross-calibrate, hybrid schemes are needed: n Imagers: SWAP, EIT, SECCHI, AIA/SDO… n Spectrometers: Solaces, Sovim, Sorce/Solstice, Snoe/Sxp, Timed/See, Solspec, Eve/SDO n Variability at various time scales n E. g. Temporal behaviours of solar flares n Effect of the nanoflare spectrum on time series n See Greenhough 2003
Variability versus UV wavelength Woods et al 2005
Short-term variability Woods et al 2005
Aeronomy Woods Rottman 2002 n UV irradiance governs n The thermal structure of the Earth atmosphere, n Its dynamics, n Its chemistry: n Photodissociation, photoionization n Cf. Ozone
LYRA objectives in aeronomy Taking advantage of the calibrated continuous measurements • LYRA channels: • 200 -220 nm 121. 6 nm Long term (27 days, activity cycle) averaging and short term (0. 01 s- tens minutes) sampling, characteristic response and relaxation times in the Earth atmosphere Study of correlations between solar VUV flux and processes in the middle atmosphere for improving the climate chemistry models Taking advantage of the measurements in occultation 17 -70 nm 1 -20 nm 1. 2. During occultations, the cadence determines the spatial resolution with which absorption in Earth’s atmosphere is sampled (30 m at 100 Hz) 3. 4. 5. Determination of the densities of O, O 2, O 3, N 2 as a function of the altitude by analyzing the absorption in each channels Monitoring of the mesosphere-thermosphere response to solar activity from eclipse measurements and comparison with atmospheric model outputs: total density and O/N 2 ratio from absorption profiles in EUV and VUV bands in high-latitude regions Variations in Ly-alpha luminescence in the geocorona due to solar activity (proton flares, CME-driven disturbances) Study of water-loss problem from the Earth atmosphere (Lya) Possible detection of Polar Mesospheric Clouds
Calibrations and radiometric model n http: //lyra. oma. be
VUV tests and calibrations made at the Berlin Electron Storage Ring (BESSY) thanks to collaborations: MPS & PTB (Physikalisch-Technische Bundesanstalt) and MPS & ROB
Channel configuration AXUV 20 D LYRA_Assembly_20050629. xls
About calibrations 1. Detector measurements (PTB, IMO, CSL) 2. Precision aperture measurements (PMOD) 3. LED measurements (PMOD, IMO) 4. Filter measurements n PTB, MPS, PMOD, ROB 5. LYRA calibration campaign n PMOD heliostat n PTB, March 2006
PC (previously “MSM”) response
Pi. N response
Hz & Ly-a filters
Al & Zr filters
Global LYRA calibration (1/2)
Global LYRA calibration (2/2)
LEDs n 2 LEDs per detector n 390 nm n 465 nm n Powered by LYRA Optical Box or by IIU n Pulsed regime n Data still to be analysed n. . LEDSPHead_LED_V 1_01. pdf n. . LED465 nm LED. pdf
SCSL possible contributions 1. 2. Calibration WG 1. Past campaign analysis 2. Cross-calibration preparation Solar irradiance WG 1. Solar spectrum inversion n n 2. Benefits of high cadence for Solar physics n n n 3. Dudok et al (statistical correlations) Hybrid inversion using SWAP and other instruments Temporal behaviors of flares Flare energy spectrum Signal processing Aeronomy WG 1. Absolute accuracy 2. Complementarities with other missions 3. Benefits of high cadence for Aeronomy (Occultations)
- Slides: 37