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ACKS seminar. December 7, 2006. Metrology of type Ia supernovae for cosmology. Claire JURAMY – Supernovae Group – LPNHE/IN2P3/CNRS. Cosmology measurements with type Ia supernovae Combined « calorimetric » analysis Modeling of type Ia supernovae Simulation of radioactive products deposition
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ACKS seminar December 7, 2006 Metrology of type Ia supernovae for cosmology Claire JURAMY – Supernovae Group – LPNHE/IN2P3/CNRS
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
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
Cosmological distance measurements • Cosmological redshift : • Cosmological distances : • Angular diameter dA • Proper motion dM • Luminosity distance dL : • Comoving density Claire Juramy
Type Ia, z = 0.93, VLT Observation of SNe Ia in SNLS • Detection • Spectrum : identification, redshift • « Multiplexed » follow-up (MegaCam) Claire Juramy
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
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
Cosmological results with SNLS M = 0.271 + 0.021 (stat) + 0.007 (sys) w = -1.023 + 0.087 (stat) + 0.054 (sys) Claire Juramy
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
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
Supernova evolution • Photospheric phase, nebular phase • “Calorimetric” behavior : total energies, nebular phase SN 1990N Bmax + 255 j Claire Juramy Å
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
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
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
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
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
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
Color during Co Fe phase • “Lira” relation for unreddened SNe Ia Claire Juramy
“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
Measurement of the green ray • SNLS filters : r’/g’ restframe, i’/r’ at z = 0.35 g’r’i’z’ Claire Juramy
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
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
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
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
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
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
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
Acquisition for noise measurements • Measurements to < 1 µV • Input resistors : simulate detector noise • Fast digitizing (1 GHz), off-line analysis Claire Juramy
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
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
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
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
Cryogenic test bench • Focal plane : detector, calibrated photodiodes, readout ASIC • Isolation from EM noise • Dual cooling system • Flexibility • Temperature and pressure monitoring Claire Juramy
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
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
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
Low Current Amplifier ASIC • Prototype • Optimization of input transistor for ultra low input current : guard rings Claire Juramy
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
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
First LED test results • Irregularities at the percent level • Need to design second diaphragm hole to avoid glancing reflexions Claire Juramy
Conclusion Claire Juramy
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
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
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
Cryogénie du banc CCD • Suivi de la température et de la pression • Performances du refroidissement : 150 K au niveau du CCD Claire Juramy
Performances du banc infra-rouge • Écran froid • Refroidissement du plan focal (plaque molybdène) Claire Juramy
Acquisition CCD • Contrôleur SDSU • Lecture : SDSU, ASIC, DSA Claire Juramy
Burnt elements • Thermonuclear energy ~ 10 x decay energy • 56Ni : lowest energy/A for Z = A/2 Claire Juramy
Comparing GRATIS to observations : total • Bolometric lightcurves : SALT, absolute calibration • Agreement (50 % efficiency), dispersions • Relations between parameters (mNi, vmax) and (s,c) Claire Juramy
Comparing GRATIS to observations : power • Same efficiency (50 %) • Heavy influence of vmax • Limits of SALT for bolometry and at late times Claire Juramy