1. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga John Vallerga, Barry Welsh, Anton Tremsin, Jason McPhate and Oswald Siegmund Experimental Astrophysics Group Space Sciences Laboratory University of California, Berkeley Photon counting detectors for sub-millisecond astronomy

2. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Over 20 UV detectors in space Active R&D program Expanding to ground based applications –Astronomy –Biology –Physics EAG specializes in photon counting MCP Detectors 25 mm Optical Tube GALEX NUV Tube 68 mm FUSE and COS FUV for HST (2007??) 200 mm

3. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Imaging, Photon Counting Detectors Photocathode converts photon to electron MCP(s) amplify electron by 10 4 to 10 8 Rear field accelerates electrons to anode Patterned anode measures charge centroid

4. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Why would you want one? No readout noise penalty –Use as many pixels as you wish Continuous temporal sampling to ~ nsecs –Choose integration period(s) after the fact or on the fly Other advantages –Selectable bandpass from soft xray to optical –Large area, curved focal planes –Cosmic ray = 1 count –LN 2 not required –Low dark current (0.16 attoamps cm -2 )

5. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga GaAs Photocathodes (GenIII) Developed for night vision tubes Can be enhanced for Blue and near IR Slight cooling required (10 4 cps at room temp)

6. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Readout Anodes Delay LineMedipix ASICCross Strip

7. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Readout Anode Performance Type Format (resels) Spatial resolution Temporal resolution Event rate Delay Line 2048 2 20µm FWHM 50 ps2 MHz Cross Strip 10k 2 9 µm FWHM 50 ps5 MHz Pixelated ASIC 256 2 55 µm pixels 1 ms2 GHz

8. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Photon Counters over CCDs Where read noise dominates sky-noise –High speed spectro-photometry When CCD readout time is longer than integration time of interest –Pulsars –Flare Stars and CVs –Short Transients Wavefront sensors for adaptive optics –Kilohertz rates supporting many actuators

9. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Current projects GaAs optical image tube for high speed imaging/polarimetry of pulsars (NSF) Optical wavefront sensor detector (NOAO) On-going analysis of GALEX transient data (NASA) Detection of space debris with LANL Biological fluorescence lifetime imaging (NIH)

10. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Detector for High Speed Polarimeter Redfren and Shearer, National Univ. of Ireland, Galway Goal is to measure all 4 Stokes parameters per pulse of the Crab simultaneously at 100 µs temporal resolution Imaging required to optimize aperture and properly subtract background

11. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Wavefront Sensors for Large Telescopes GaAs image tube Medipix readout 1000 frames/sec 5000 centroids/frame 1000 events/centroid 5 GHz ct rate

12. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga GALEX Transient Survey NUV and FUV detectors, 45 cm telescope 1.5  FOV 5 millisec. resolution 84 objects found in 1st year –RR Lyrae, dMe flares, SXRTs –GJ 3685 dM4e had a 12 mag increase in 200 sec. Satellites and space debris

13. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Flares NUV FUV

14. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Debris and satellite movies

15. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Summary Imaging, photon counting detectors have a place in ground based astronomy, especially for fast transients As the QE increases, so do the niche applications Our new vacuum tube is designed to easily integrate into an industrial production line “Application Specific” detectors

16. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga

17. 2nd Zwicky Informal Workshop - Berkeley 2005 May 26, 2005John Vallerga Spatial Resolution (cont’d) 12 µm pore glass MCPs7 µm pore glass MCPs Cross Strip readout of Glass MCPs