1. Page 1 Science Payload and Advanced Concepts Office STJs as Photon Detectors

2. Page 2 Science Payload and Advanced Concepts Office STJs: principle of operation photon with energy E breaks Cooper pairs  quasiparticles for Ta:  ~0.7 meV  N 0 ~ 850 / eV multiple tunneling  detected charge: resolving power limited by statistics of QP generation and tunneling: Ta:  E ~ 2.0 eV @ E=500eV Additional resolution degradation: - electronics noise, infrared background - non-uniform detector response

3. Page 3 Science Payload and Advanced Concepts Office STJs: energy resolving power

4. Page 4 Science Payload and Advanced Concepts Office Ta-based STJs (for UV/visible) Ta layers: 100 nm Base: epitaxial (RRR~45) Al layers: 30 nm Nb wiring (QP out diffusion) AlOx barrier: ~1 nm  tunnel time ~ 0.5-1  s low leakage: <0.1 pA/  m 2 detector area: 10x10 - 100x100  m 2 Al Ta Sapphire substrate SiOx Nb Back-illumination Front-illumination

5. Page 5 Science Payload and Advanced Concepts Office S-Cam 3 Detector: 10x12 Ta/Al STJs 371  m = 8.9” 446  m = 10.7” S-Cam 3: 10x12 pixels ; 33x33  m 2 FOV = 9x11 arcsec 170  m = 4” S-Cam 2:

6. Page 6 Science Payload and Advanced Concepts Office S-Cam 3 Detector 120 pixels ALL subgap currents ~100 pA  low noise operation Uniform responsivity across array Fiske modes Residual Jc Bias region

7. Page 7 Science Payload and Advanced Concepts Office S-Cam 3 image (9”x11”)

8. Page 8 Science Payload and Advanced Concepts Office S-Cam 6: improved spectral resolution Aluminium STJs: Tc=1.2K  T<100mK (ADR) expected resolution 2x better than Ta Measured resolution ~ Ta (mechanism and solution under investigation) Next step: molybdenum STJs: Tc=0.9K better efficiency than Al

9. Page 9 Science Payload and Advanced Concepts Office Distributed Read Out Imaging Devices (DROIDs) absorber with 2 STJs for readout: Position sensitivity: S1 - S2 Photon energy:S1 + S2 sapphire substrate SiOx Al (65 nm) AlOx Nb contacts Ta top electrode 200  m 50  m - - - - - - - - Ta absorber

10. Page 10 Science Payload and Advanced Concepts Office 100x20  m 2 absorber with 20x20  m 2 STJs  E=2.4 eV (FWHM) at E=500 eV DROIDs as X-ray detectors

11. Page 11 Science Payload and Advanced Concepts Office 100x100  m 2 absorber with 20x20  m 2 STJs 2D DROIDs as X-ray detectors 10 keV diffraction pattern from 5  m pinhole with 2-D DROID

12. Page 12 Science Payload and Advanced Concepts Office Detection efficiency for 500nm thick DROIDs Ta Mo

13. Page 13 Science Payload and Advanced Concepts Office Possible detector layout for NFI1 on XEUS Array of DROIDs 0.5x1.7 arcmin FL=30m  4.4x15mm 750x75 micron DROIDs  6x200 DROIDs 1.7’ = 15mm = 200 DROIDs 0.5’ = 4.4mm = 6 DROIDs

14. Page 14 Science Payload and Advanced Concepts Office Latest Ta/Al STJs for optical Ta layers: 100 nm Base: epitaxial (RRR~30) Al layers: 30 nm Nb wiring (QP out diffusion) AlOx barrier: ~1 nm  tunnel time ~ 0.5-1  s low leakage: <0.1 pA/  m 2 detector area: 10x10 - 100x100  m 2

15. Page 15 Science Payload and Advanced Concepts Office Latest Ta/Al STJs for optical

16. Page 16 Science Payload and Advanced Concepts Office Latest Ta/Al STJs for optical: resolving power