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maXs : Metallic Magnetic Calorimeter Arrays for High Resolution X-Ray Spectroscopy

Explore the features and advantages of MMCs, a high-resolution X-ray spectroscopy technology providing excellent energy resolution, large bandwidth, and fast signal processing. Learn about the innovative detector design, thermodynamic properties, and applications in highly charged ion spectroscopy. Gain insights into the working principle, sensor materials, and numerical optimization for optimal performance.

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maXs : Metallic Magnetic Calorimeter Arrays for High Resolution X-Ray Spectroscopy

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  1. maXs: Metallic Magnetic Calorimeter Arrays for High Resolution X-Ray Spectroscopy D. Hengstler, J. Geist, C. Schötz, S. Allgeier, M. Friedrich, S. Kempf, L. Gastaldo, A. Fleischmann, C. Enss KIP, Heidelberg University

  2. Working principle of MMCs T t Fundamental energy resolution Advantages Sensor material • No dissipation in the sensor • No galvanic contact to the sensor • AgEr • AuEr

  3. MMC key features • Large energy bandwidth / dynamic range 0..>100 keV Nosaturation at higherenergies But quantumefficiency < 100 %

  4. MMC key features • High energy resolution • High linearity • Fast signal rise time 1.6eV @ 6keV < 100ns

  5. Planar gradiometric detector geometry • Particle/X-ray absorber • Electroplated Au • 3 µm … 200 µm high • Connected via stems • Planar temperature sensor • Sputtered AuEr/AgEr • Superconducting pickup loop • Sputtered Nb • Ic up to 200 mA • Gradiometric design • Inductive coupling to SQUID 500 µm

  6. Au:Er 300 ppm Au:Er 300 ppm Specific heat C [104 J mol1K1] Magnetization M [A/m] Inverse Temperature T1 [K 1] Temperature T [mK] Planar gradiometric detector geometry • Particle/X-ray absorber • Electroplated Au • 3µm … 200µm high • Connected via stems thermodynamical properties ofAu:Erare well understood • Planar temperature sensor • Sputtered AuEr/AgEr • Superconducting pickup loop • Sputtered Nb • Ic up to 200mA • Gradiometric design • Inductive coupling to SQUID electrons signal size can be calculated with confidence numerical optimization of detector design 500 µm

  7. Planar gradiometric detector geometry • Particle/X-ray absorber • Electroplated Au • 3 µm … 200 µm high • Connected via stems • Planar temperature sensor • Sputtered AuEr/AgEr • Superconducting pickup loop • Sputtered Nb • Ic up to 200 mA • Gradiometric design • Inductive coupling to SQUID 500 µm

  8. maXs overview • maXs-20 • maXs-30 • maXs-200 250 µm 500 µm 1 mm • High resolution X-ray spectroscopy • Spectroscopy of highly charged ions • g-spectroscopy

  9. maXs overview • maXs-20 • maXs-30 • maXs-200 250 µm 500 µm 1 mm Energy resolution DEFWHM = 1.7 eV • High resolution X-ray spectroscopy • Spectroscopy of highly charged ions • g-spectroscopy See poster Tu, 17:45 by M. Krantz (#150) Prototype fordirectread-out

  10. maXs overview • maXs-20 • maXs-30 • maXs-200 250 µm 500 µm 1 mm • High resolution X-ray spectroscopy • Spectroscopy of highly charged ions • g-spectroscopy

  11. 2d-array maXs-30 • 8x8 absorbers • Electroplated gold • 25 µm thick • Stopping power: • 97 % @ 20 keV • 73 % @ 30 keV • 45 % @ 40 keV 4 mm Read-out by 32 two-stage SQUID channels

  12. Temperature-correction 4 non-gradiometric detectors as on-chip thermometers - allow to correct for temperature fluctuations Asymmetry ~ 10-4 Reduces cross-talk, only sensitive to temperature differences

  13. Energy resolution Single pixel, few hours of measurement time @ baseline: 7.5 eV FWHM @ 60 keV: 9.8 eV FWHM → Resolving power E/DE > 6000

  14. Energy resolution Spectrum from 241Am and 233U sources See talk Fr, 10:30 by J. Geist

  15. Energy resolution After co-adding pixels over ~40 days of measurement gain instabilities intrinsic resolution Still degraded from gain instabilities in the order of 2·10-4

  16. Linearity Non-linearity only 1 % @ 60 keV As expected from thermodynamic principles

  17. Linearity Calibration based on g-lines of 241Am and 233U sources & Cu X-rays Remaining uncertainties ~ 1 eV

  18. Applications maXs-30: Isomer 229mTh maXs-IAXO: Axion search See poster Tu, 17:45 by L. Gastaldo (#331) See talk Fr, 10:30 by J. Geist

  19. Spectroscopy of highly-charged ions Atomic radius ~Z-1 Transition energies ~Z² Lamb Shift ~Z4 Fine structure splitting ~Z4 Hyperfine splitting ~Z3 H-like Uranium Precisemeasurementof Lamb shift - Study of QED in extreme E-fields

  20. maXs-30: Spectroscopy of HCIs Storage Rings EBITs ions maXs-30 e- High Z ions up to Uranium - High charge states No Doppler shift or broadening - Easier to operate

  21. maXs-30: Spectroscopy of HCIs Storage Rings EBITs High Z ions up to Uranium - High charge states No Doppler shift or broadening - Easier to operate Lyman series of Xe53+ and Xe52+

  22. maXs-30: EBIT spectroscopy Helmholtz coils Helmholtz coils Ring electrode Electron collector cathode Magnetic field Electron beam Different charge states of Fen+ Ions

  23. maXs-100: Lamb shift of U91+ • 8x8 absorbers • Electroplated gold • Area 1 cm² • 100 µm thick • Stopping power: • 71 % @ 90 keV • 53 % @ 110 keV • 40 % @ 130 keV • Expected energy resolution • ~ 25 eV 1 cm In preparation for 2020

  24. Summary • MMCsprovide • High energy resolution • Large energy bandwidth • High quantumefficiency • Excellent linearity • Fast signal rise time • maXs-30 detector • First 2d array • DEFWHM= 9.8 eV @ 60 keV • Non-linearity ~ 1 % • key technology for many applications: • X-ray spectroscopy of highly charged ions • Isomer state of 229Th • Many more …

  25. Summary • MMCsprovide • High energy resolution • Large energy bandwidth • High quantumefficiency • Excellent linearity • Fast signal rise time • maXs-30 detector • First 2d array • DEFWHM= 9.8 eV @ 60 keV • Non-linearity ~ 1 % • key technology for many applications: • X-ray spectroscopy of highly charged ions • Isomer state of 229Th • Many more … Thank you for your attention

  26. Cryogenic Setup Dry ³He/4He dilutionrefrigerator -metalshielding Coppershielding Wired for 32 two-stagedc-SQUIDs Al shielding Nbshielding X-raywindows: 41.5m Al coatedMylar 1 25m Bewindow 16 2SQUID arrays maXs-30 detector 8 4 SQUIDs

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