Metrology of type Ia supernovae for cosmology

1. ACKS seminar December 7, 2006 Metrology of type Ia supernovae for cosmology Claire JURAMY – Supernovae Group – LPNHE/IN2P3/CNRS

2. Cosmology measurements with type Ia supernovae • Combined « calorimetric » analysis • Modeling of type Ia supernovae • Simulation of radioactive products deposition • Analysis of late time spectra • « Green ray » estimator • Instrumentation for a large focal plane camera • ASIC for CCD readout in large mosaic detectors • Cryogenic test bench • Calibration bydirect illumination with LEDs Claire Juramy

3. Expansion and content of the universe • Homogenous, isotropic universe + general relativity • Friedman equations : • R : scale factor, H : expansion rate, k : curvature • Accelerated expansion : • Cosmological constant  : w = -1, w’(z) = 0 • Dark energy : equation of state wX = pX / X < - 1/3 Claire Juramy

4. Cosmological distance measurements • Cosmological redshift : • Cosmological distances : • Angular diameter dA • Proper motion dM • Luminosity distance dL : • Comoving density Claire Juramy

5. Type Ia, z = 0.93, VLT Observation of SNe Ia in SNLS • Detection • Spectrum : identification, redshift • « Multiplexed » follow-up (MegaCam) Claire Juramy

6. Measurements of dL with SNe Ia (1) • Measurement of flux in several filters (u*g’r’i’z’) • « Flat fields » for detector calibration • Point Spread Function fitting • Calibration with standard stars, atmospheric extinction • Corrections due to differences in filters (UBVRI) and spectra Claire Juramy

7. Measurements of dL with SNe Ia (2) • Nearby and distant supernovae : flux in restframe filters, cross-filter calibration • SuperNova Factory : SNe Ia spectrophotometry at low z • Empirical relations to reduce the dispersion of instrinsic luminosities (Pem) : « stretch » and « color » • SNLS : SALT (Spectral Adaptative Lightcurve Template) : fits measured lightcurves to get mB*, s, c Distance modulus : B = mB* - MB = 5 log(dL/10pc) Absolute magnitude : MB = M -  (s-1) + c Claire Juramy

8. Cosmological results with SNLS M = 0.271 + 0.021 (stat) + 0.007 (sys) w = -1.023 + 0.087 (stat) + 0.054 (sys) Claire Juramy

9. Cosmology measurements with type Ia supernovae • Combined « calorimetric » analysis • Modeling of type Ia supernovae • Simulation of radioactive products deposition • Analysis of late time spectra • « Green ray » estimator • Instrumentation for a large focal plane camera • ASIC for CCD readout in large mosaic detectors • Cryogenic test bench • Calibration bydirect illumination with LEDs Claire Juramy

10. Type Ia supernovae • White dwarf C+O, companion, Chandrasekhar mass (1.38 M) • Thermonuclear explosion : intermediate mass elements (Si, Mg, Ca), 56Ni, iron peak elements • Ejecta speed ~10,000 km/s • Decay of radioactive elements : 56Ni ( = 8.8 j) →56Co ( = 111 j) →56Fe • Lightcurves Claire Juramy

11. Supernova evolution • Photospheric phase, nebular phase • “Calorimetric” behavior : total energies, nebular phase SN 1990N Bmax + 255 j Claire Juramy Å

12. Model for gamma ray escape • Simulation of the decay of radioactive elements and of the absorption of the products (, +) in the expanding supernova • Physical parameters : 56Ni mass, kinetic energy (density profile, maximal speed), stratification • Photoelectric effect, Compton scattering (E  < 4 MeV) Claire Juramy

13. GRATIS (Gamma Ray Absorption in Type Ia Supernovae) • Monte-Carlo • Propagation along a fixed axis : computing speed, decorrelates direction and energy after Compton scattering Direct Monte Carlo Decay total Absorbed total Absorbed in Ni Absorbed in Fe Absorbed in Si Claire Juramy

14. Results from GRATIS • Deposited power depending on nickel mass mNi and ejecta speed vmax • Simulation based only on physical parameters Vmax = 11,000 to 19,000 km/s mNi = 0.3 to 1.0 M Claire Juramy

15. Comparing GRATIS to observations • Bolometric lightcurves : SALT, absolute calibration • Agreement (50 % efficiency), dispersions • Relations between parameters (mNi, vmax) and (s,c) • Limits of SALT for bolometry and at late times Claire Juramy

16. Late-time spectra decomposition • Publicly available SNe Ia spectra : low signal, few spectra, quality of data • Normalized in flux on common interval • Very late-time vector (>+200 d) + orthonormal vector (60 to 200 d) Claire Juramy

17. 60 j 200 j Co and Fe components • Projection, linear with %Fe in 56Co →56Fe • Templates for “Co” and “Fe” • Not enough data for “calorimetry” : cannot determine relative scintillation efficiency of Co and Fe Claire Juramy

18. Color during Co  Fe phase • “Lira” relation for unreddened SNe Ia Claire Juramy

19. “Green ray” • Fast change in color, transition towards emission spectrum • Optimal estimator : selected peaks, practical : two sharp filters below and above ~5350 Å • Quantities : speed, phase and height of the color jump Flux ratio between filters / same around Bmax Claire Juramy

20. Measurement of the green ray • SNLS filters : r’/g’ restframe, i’/r’ at z = 0.35 g’r’i’z’ Claire Juramy

21. Green ray time and stretch parameter • i’/r’ correlates with stretch within redshift range around 0.35 • Common physical origin • Better evaluation of the “stretch” parameter Claire Juramy

22. Cosmology measurements with type Ia supernovae • Combined « calorimetric » analysis • Modeling of type Ia supernovae • Simulation of radioactive products deposition • Analysis of late time spectra • « Green ray » estimator • Instrumentation for a large focal plane camera • ASIC for CCD readout in large mosaic detectors • Cryogenic test bench • Calibration by direct illumination with LEDs Claire Juramy

23. Large mosaic detectors projects • Possible improvements for cosmology with supernovae : increase number, higher redshifts, decrease systematic errors • Large focal plane • Optical (CCDs) and/or IR detectors • Dedicated campaigns • Projects : • In space : SNAP (~ 700 Mpixel, 0.7deg², CCDs and IR up to 1.7 m), others : JDEM, DUNE • On the ground : LSST (> 3 Gpixel, 10 deg²), others MegaCam (CFHT) SNAP Claire Juramy

24. Readout electronics for large mosaics • Constraints on front-end electronics : temperature, power, irradiation (in space) • Integrated electronics : compact, low power, adapted to low temperatures, radiation hardness / extra noise, limited voltage • « Video » chip : analogic functions, ADC • First ASIC : testing of analogic functions - AMS 0.35µ Claire Juramy

25. CCD readout • Readout capacitor ~ 40 fF, 4 µV/e- • Reset noise • Correction strategies : • Clamp and Sample : reset to reference voltage • Dual Slope Integrator : measure of reference and signal, subtraction Claire Juramy

26. DGCS (Dual Gain Clamp and Sample) ASIC • 17-bit dynamic : 2 e- (CCD noise) to 250,000 e- (CCD well capacity) – 4 µV/ e- • Voltage range : +1.5 / - 3.5 V or + 2.5 V • Readout speed (~1MS/s) : ADC comparator limits dynamic to ~14 bits • Dual gain solution (x 3 et x 96) + 2x 12-bit ADCs • Clamp / DC restore Claire Juramy

27. parasitic R DGCS ASIC : functional testing • Offset and gain problem on high gain channel : x 60, - 600 mV • Identification and measurement of parasitic resistors • Linearity up to specifications LSB 12 bits Low gain High gain

28. Acquisition for noise measurements • Measurements to < 1 µV • Input resistors : simulate detector noise • Fast digitizing (1 GHz), off-line analysis Claire Juramy

29. ASIC DGCS : low noise analysis Low gain High gain 1 MΩ 20 kΩ 2 kΩ 500 Ω 50 Ω • Noise spectra • Thermal noise of input resistors • Intrinsic noise at optimal readout time (80 µs) : • x 60 : 1.1 µV • x 3 : 1.8 µV • Simulation package validated Measures parasitic C parasitic R Simulation Claire Juramy

30. 1/f noise Simulation R = 500 k and 2 k Measurements R = 50  to 1 M • 1/f noise dominant at low frequencies (20 kHz) • Conforms to simulation Claire Juramy

31. Clamp and Sample vs. Dual Slope Integrator Readout noise Clamp noise DSI 2 kΩ DSI 500 Ω DSI 500 Ω (no aliasing) C&S 500 Ω 1 e- ½ e- • C&S : longer integration time for equal pixel time, single clock, clamp noise • DSI : low frequency noise suppression, need DC restore function, need precision on timing Claire Juramy

32. Cold and irradiation tests • Functioning down to 130 K • Irradiation with cobalt 60 source (180 krad) • Viable solution for mosaic readout in ground and space projects • Future developments : adding ADCs, Low Current Amplifier Claire Juramy

33. Cryogenic test bench • Focal plane : detector, calibrated photodiodes, readout ASIC • Isolation from EM noise • Dual cooling system • Flexibility • Temperature and pressure monitoring Claire Juramy

34. Cryogenic commissioning • Cold screen ~ 100 K • Cryogenerator : focal plane ~ 70 K • Available for future electronic tests ASIC cold screen 145 K N2 entrance 95 K Claire Juramy

35. SNDICE : SuperNova Direct Illumination Calibration Experiment • Photometric calibration for SNLS : instrumental calibration • LED properties • Direct illumination setup : • Less stray light • Controlled flux • Alignment • Wavelength range : ~20 LEDs • Precision, accuracy : • Calibrated source • Feedback for stability • Additional check Claire Juramy

36. LED source DACs FPGA x 20 computer T ADC LCAs Mux x 20 CLAP Proposed system architecture Camera support beam Out of the light path (Cooled Large Area Photodiode) MegaCam Focal plane (Low Current Amplifier) Claire Juramy

37. Low Current Amplifier ASIC • Prototype • Optimization of input transistor for ultra low input current : guard rings Claire Juramy

38. Developments and tests • Preliminary calibration work on test bench : • Calibration of LEDs : X, Y, T, spectrum, stability with feedback • Cross-calibration of CLAP with NIST standard 70 fA x 20 s Claire Juramy

39. First LED test results • Oversampling of the beam (photodiode: 2.4 mm) • Subtraction of dark current, comparison of flux to reference at regular intervals Claire Juramy

40. First LED test results • Irregularities at the percent level • Need to design second diaphragm hole to avoid glancing reflexions Claire Juramy

41. Conclusion Claire Juramy

42. Détecteurs : CCD du LBNL • CCD épais haute résistivité du LBNL : « back-illuminated », sensibilité de l’UV au proche infra-rouge, pas de « fringing » • Forte tension de biais, polarité inversée Claire Juramy

43. Active Pixel Sensor infra-rouge Mesuré Attendu Objectif • Substrat photosensible HgCdTe ou InGaAs • Matrice de lecture : « BareMux » • H2RG (Rockwell) : pixels de référence, fenêtres • Bruit « extra noise » : supprimé par nouveau procédé Claire Juramy

44. Banc de test CCD • Refroidissement à l’azote liquide • Suivi de la température et de la pression • Plan focal : photodiodes calibrées • Lecture CCD : contrôleur SDSU, intégration système LPNHE • Éléments optiques Claire Juramy

45. Cryogénie du banc CCD • Suivi de la température et de la pression • Performances du refroidissement : 150 K au niveau du CCD Claire Juramy

46. Performances du banc infra-rouge • Écran froid • Refroidissement du plan focal (plaque molybdène) Claire Juramy

47. Acquisition CCD • Contrôleur SDSU • Lecture : SDSU, ASIC, DSA Claire Juramy

48. Burnt elements • Thermonuclear energy ~ 10 x decay energy • 56Ni : lowest energy/A for Z = A/2 Claire Juramy

49. Comparing GRATIS to observations : total • Bolometric lightcurves : SALT, absolute calibration • Agreement (50 % efficiency), dispersions • Relations between parameters (mNi, vmax) and (s,c) Claire Juramy

50. Comparing GRATIS to observations : power • Same efficiency (50 %) • Heavy influence of vmax • Limits of SALT for bolometry and at late times Claire Juramy