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High Energy, High Resolution X-Ray Spectroscopy

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Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21High Energy, High Resolution X-Ray SpectroscopyEric SilverHarvard-Smithsonian Center for AstrophysicsPhoton Energies > 10 keVMeasurements Important to Astrophysics, Atomic and/or Nuclear physicsTwo Science TopicsNuclear Line AstrophysicsQED Related Heavy Ion Spectroscopy USE MICROCALORIMETERSE E/ 1 0 0 0Nuclear Line AstrophysicsDirect probe of one of the most violent events in the universea Supernova explosion that expels the heavy elements into the ISM from the nuclear furnace in which they were created44Ti is a key diagnosticProduced deep in the stellar core60 year half-lifelonger than the few years required for the overlying strata to become optically thin at high energiessufficiently short that the 44Ti remains localized around the SN site while it emits intenselyModel calculations of nucleosynthesis yields for Type Ia and Type II SN show that conditions for 44Ti production are significant only within the central cores of massive stars or in white dwarfs following a surface detonation.Mass of 44Ti is an important diagnostic of the most extreme densities and temperatures.Vink et al. 2001Detection of the 67.9 and 78.4 keV Lines in Cas A by Phoswich Detection System aboard BeppoSAXFlux of (2.1 ±0.7) x 10-5 ph cm-2 s-1Initial 44Ti mass of (0.8 – 2.5) x 10-4 MΘ44Ti Decay Scheme1157 keV line detected by (CGRO)/COMPTEL (Iyuden et al.1994)Flux of (3.3 ±0.6) x 10-5 ph cm-2 s-1High Energy MicrocalorimeterSilver, E., et al., 2002, AIP Conference Proceedings, Volume 605, 555.Modest FocusingMultilayered OpticsLow Background MicrocalorimeterHigh Spectral ResolutionThe folded scattering curve predicts a HEW of 34 arcsec for single reflection telescope made from this plastic. Expected HEW if the telescope was built perfectly, i.e., there are no figure errorsThe telescope needs to being nothing more than a “light bucket” with a HEW ~ 4 arcmin. work with the prototype conventional optic. (Schnopper et al. 2003)Requirements can be easily met. Thin Foil Plastic OpticsTelescope Effective Area (cm2)020406080Energy (keV)20 30 40 50 60 70 80 90Counts / 10 eV Bin in 106 s051015202530354044TiSn Ka EscapeLines From 44Ti67.5 68.0 68.50510152025303550 eVFWHMMultilayer TelescopeBandpassModest focusing (<4 arc min), multilayered optics to reduce the background and enhance the effective area in a balloon-borne experimentA 20 x 20 array of microcalorimeters with 50 eV resolution3 σ narrow line sensitivity at 68 keV is 3.3 a 10-7 ph cm-2 s-1 in 106 s; 50 times more sensitive than INTEGRALSufficient spatial and spectral resolution to determine the extent and the velocity distribution of the 44Ti emitting regionNon-X-ray background is almost 3 orders of magnitude less than typically achieved in this energy regionRecent Technical AdvancesMicrocalorimetersSoft X-Ray detectors Reduced readout noise 3 eV at 6 keV (60 mK) Consistent with model calculationsAbsorberThermistorHeat SinkAluminumWires = C / GX-RayTantalizing Outlook for high energies Earlier measurement (80 mK) 50 eV 30 eVUse soft x-ray thermistor(60 mK) Larger R and dR/dT S/N increases Larger volume x-ray absorbers may improve Q.E. 4-foldThis large spiral prototype lens is wound with seven turns of W coated PET plastic. Twenty-four ribs in the front and back wheels support a 50 mm wide, single strip of plastic. The pins are 1.27 mm in diameter and the spacing between the shells is 2 mm. A 6 in scale is placed in front of the lens.Novel Conical Spiral for Astronomy Single Reflection (ε = 60%) 1.6 x Reflection efficiency of 2 reflectionsX-ray OpticsSmall Cylindrical Spiral LensesFor the LaboratoryPotential Increase in Collecting Area4-5 times (detector efficiency)1.6 times (reflection)6.4 – 8 (Total)Flight ProgramTest flight of optics in September 2005 aboard MSFC gondolaSeeking support to finish microcalorimeter array and electronicsTo be incorporated in Ball Aerospace lightweight dewarCas A 20 days Fairbanks, AlaskaQED : Basis and cornerstone of all present field theoriesEnormous success in predicting properties of electrons in weak fieldsHoweverA precise test is still pending for strong field limit where new phenomena may appearComparison of predictions and experimentally determined energy levels of strongly bound electrons provides a critical test of QEDGSI-Accelerator FacilityUNILACSISESR11.4 MeV/u U73+10 - 500 MeV/u U92+up to 1000 MeV/u U92+UNILACGAS JETGe(i)90º48º48º132º)cosθβ(1EElabprojlabγN Ion  1081 10 20 30 40 50 60 70 80 9010910101011101210131014101510161s<E> [V/cm]Nuclear Charge, Z1s-ground state: increase of the electric field strength by six orders of magnitudeAtomic Physics in Extremly Strong Coulomb FieldsZ = 92H-like UraniumEK = -132 - 103 eV<E>= 1.8 - 1016 V/cmHydrogenEK = -13.6 eV<E>= 1 - 1010 V/cmZ = 1Quantum Electro- DynamicsSelf EnergyVacuum PolarizationThe Structure of One-Electron Systems2p3/22p1/2Ly α1(E1)Ly α2(E1)QEDDirac-34.1 keV-34.2 keV-131.8 keV-132.2 keVQED Corrections∆E ~ Z4 / n3Z: nuclear charge numberN: principal quantum numberAtomic systems at high Z Large relativistic effects on energy levels and transition rates (e.g. shell and subshell splitting)Large QED correctionsTransition energies close to 100 keVCurrent Status∆E (β) ∆E (fit) ∆E (geometry) Ly α1± 2.6 eV ± 9.7 eV ± 8.5 eV 102170.7 ± 3.2Stöhlker et al. Phys. Rev, 85, 15, 2000What can the microcalorimeter add?A Self-Calibrating Measurement !Better Energy Resolution !E proj = γ ( 1 – β cos Θlab ) E lab Determined from the Balmer spectroscopy of line energies known to 0.1 eVUltimately, precision can be 1 eV or betterEnergy (keV)0102030405060Counts0510152025Energy (keV)010203040506070Counts0102030One Hour of Background Data With Jet Target On But Microcalorimeters BlockedFirst Operation of SAO Microcalorimeter at the GSI ESRAM241 Calibration With the Jet Target OnX-Ray Studies for Au 78+Commissioning of a Microcalorimeter at the ESR Storage RingSilver, E., et al., 2003, Nuclear Instruments and Methods in Physics Research A 520, 60.Spectrum obtained during parasitic beam time in March 2003Microcalorimeter + EMI shield installed at ESRAnalysisAu78+ 3d5/2 – 2p3/2 12.161 keV (rest)Microcalorimeter 7.98 ± 0.01 keVDoppler correction = 0.656 ±


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