Latest Advancements in Microchannel Plate Imaging Detectors John

Latest Advancements in Microchannel Plate Imaging Detectors John Vallerga Space Sciences Laboratory University of California, Berkeley MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Photon counting (x, y, t) Count Events Threshold Charge integrating Q V ± sv ADC Events ± s. Events MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Example: Centroid in presence of readout noise 1000 photons 10 photons 8 x 8 Noiseless 35% QE 8 x 8 2. 5 e- rms 90% QE - 6 x 6 2. 5 e- rms 90% QE - 4 x 4 2. 5 e- rms 90% QE - MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Microchannel Plate electron amplifier that retains position information Pore size Gain Time Jitter ~ 2 to 40µm ~ 10 to 108 ~ 30 ps MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Microchannel Plate Detector Photon counting, imaging, with event time tagging • Photocathode converts photon to electron • MCP(s) amplify electron by 104 to 107 • Rear field accelerates electrons to anode • Patterned anode measures charge centroid MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

MCP Detectors at SSL Berkeley COS FUV for Hubble (200 x 10 mm windowless) 18 mm Optical Tube GALEX 68 mm NUV Tube 200+ “detector years” in space including mission to Pluto MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Readout Anode Types (partial list) Cross Delayline (XDL) Cross Strip (XS) Medipix ASIC Intensified CCD 4 amps Gain ~ 107 Rate ~ 200 k. Hz t ~ 100 ps 2 x N amps Gain ~ 106 Rate ~ 2 MHz t ~ 100 ps N x N amps Gain ~ 104 Rate ~ 200 MHz t ~ 1 ms MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Tradeoff example (XDL) High gain Better resolution Lower power Long lifetime MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Microchannel Plate Sensor Applications M 101 Fluorescent dye decay time Biological lifetime fluorescence imaging (UCLA) Low Light Ladar - 3 D imaging Ponderosa Pine 3 D data cube - RULLI, LANL UV Astronomy (GALEX) High time resolution Astronomy 33 ms period, 250µs resolution MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

High Speed Imaging Astronomy Crab Pulsar B band light curve (1 m telescope on Moonlit night) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Meteor & Satellite Detection Meteor track in AH-Her field 5 ms to cross 6’ FOV. ~11 km/sec if at 30 km 2 ms time frames MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Meteor & Satellite Detection Satellite track in FL-Vir field ~8. 5 km/sec in low earth orbit 5 ms frames MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Photon Counting MCP Detectors Advantages Spatial resolution < 12µm FWHM Temporal resolution < 100 ps (rms) Format > 100 mm Dynamic range > 107 Radiation hard Curved focal planes Room Temperature Disadvantages Vacuum operation pumps, tubes or space Lifetime ~ Coulombs cm-2 Photoelectric QE ~ 50% to 10 -12 MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Performance examples Photocathode QE Ga. N Temporal resolution Ga. As Super. Gen. II S 20 Photocathode types for UV, visible & NIR are improving. MCP timing jitter ~100 ps FWHM measured with pulsed laser MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Time of flight at ALS Berkeley Scattered 60 e. V photons Photo-electron spectrum Tremsin et al Nuclear Instruments and Methods in Physics Research A 580 (2007) 853– 857 MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

FUSE MCP gain loss (Sahnow, SPIE 5488, 2004) Total fluence map (through 2004) Gain vs. fluence MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Cross Strip Anode Designs 22 mm round cross strip 45 mm square Cross Strip Anode with 0. 64 mm finger period. All metal and ceramic. 22 mm round cross strip showing vias and connector MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

22 mm Cross Strip, Sealed Tube with Super. Gen. II photocathode. 22 mm Cross Strip sealed tube Super. Gen. II photocathode (Photonis) Anode vias and signal connector 22 mm round cross strip tube showing vias and connector 22 mm cross strip anode MCP sealed tube in housing with RD 20 64 channel ASIC board MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Cross Strip Electronics (64 x 64 strips) Octal ADC FPGA 50 MHz Xilinx (x 16) Virtex 5 (x 2) ASIC Preshape 32 4 x 32 ch. 77 Gbps MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

22 mm Cross Strip Open Face Imaging Detector Tests Uniformly illuminated image for the open face 22 mm cross strip detector showing a grid mask (1. 25 mm period) placed on the surface of the MCPs. Close up image showing the 40µm grid wires, a grid defect, and the MCP multifiber hexagonal pattern. MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Imaging tests - resolution Zoomed - 20 m FWHM avg. 40 mm - 0. 5 x 0. 5 mm pinhole grid MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

18 mm Cross Strip Sealed Tube Imaging vs. Event Rate Global counting rate Local area charge depletion Counting rate performance for a sealed tube 22 mm cross strip detector and PXS system showing the effects of the ~130 ns dead time of the electronics. Measured event rate in a 100 µm spot area as a function of the relative input rate for two MCP stacks with resistances of 170 MΩ. (Tube 1) and 105 MΩ (Tube 2). MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Proposed 8 ch. XS ASIC (with Gary Varner, U. Hawaii) Features: GHz front end amp sampling 2048 analog samples (2µs) Wilkinson ADC 4 Gbps LVDS outputs FPGA control and sparsification Potential for 30 MHz event rate (64 x 64) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

MCP Local Rate limitations Local output event rate limited by the time it takes for microchannel outputs to recharge from previous pulse High local rate in many 100µm spots Function of event gain, plate resistance and spot size Gain map of above image showing local loss of gain and saturation of local count rate at a gain of 500, 000. MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Medipix/Timepix x-ray imager MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Medipix/Timepix ASIC readout • 256 x 256 array of 55 µm pixels • Integrates counts, not charge • 100 k. Hz/pxl • Frame rate: 1 k. Hz • Low noise (100 e-) = low gain operation (2 ke-) • GHz global count rate • ~1 W watt/chip, abuttable ~ 500 transistors/pixel • Developed at CERN MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Vacuum Tube Design MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Vacuum Tube Design MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Vacuum Tube Design MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Vacuum Tube Design MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Second tube process Success! Qualification: poor optical QE MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Old WWII watch movie 66 MHz input rate MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Old WWII watch movie 2 Bkgd. 002 ct/pxl/s Room Temp (radium dial) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

City Movie - 1 Cycle Line Frequency Log greyscale 40 s shutter 3 phase evident MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Centroiding Algorithm using Timpix amplitude information For each Frame § Find local event peaks in 3 x 3 “boxcar” smoothed image For each event § Calculate simple 5 x 5 “center of gravity” § Threshold on event sum and size § Apply distortion correction § Histogram centroids into high resolution 2 D image Charge cloud from single photon event MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Original Medipix mode readout 256 x 256 (14 mm) UV image limited by 55 m pixel MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Zoomed UV image of pattern in Medipix mode Pattern 3 -2 (= 9 lp/mm) barely resolved MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Timepix centroided mode Factor of 8 improved resolution! 256 x 256 converted to 8192 x 8192 pixels (1. 7µm pixels) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

MCP pores resolved (10 on 12 micron) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Evolution of MCP detectors Count rate (cps) 1985 2010 Improvement 5000 5 x 106 1000 10 10 Spatial Resolution (µm) 100 Lifetime (cts/mm) 109 1012 1000 Optical QE (%) ~15 ~30 2 Limited by MCP technology! Size (mm) 100 1 Pore diameter (µm) 12 6 2 Lifetime (C/mm) . 01 1 MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Atomic layer deposition (ALD) Allows engineering of surfaces after MCP pores are fabricated – Optimize secondary electron coefficient for gain – Optimize resistivity Separates microchannel fabrication from surface preparation – MCPs can be made from any glass, alumina, plastic – Lithographic techniques for larger arrays of pores Photocathodes deposited on MCP(? ) – Passivated (Al 2 O 3) surfaces – Higher QE of opaque photocathodes MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Borosilicate glass MCP 33 mm substrate from INCOM Resistive, SEC, and conductive coatings by Arradiance Microscope image showing 40 µm holes in hexagonal array with L/d ratio of 40 MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Results from ALD coated Incom glass Gain vs. extracted charge Gain vs. voltage ALD coating done by Arradiance Inc. (www. arradiance. com) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

SSL-UCB, ALD/Incom MCP Test It works! UV illuminated image, 33 mm ALD/borosilicate MCP pair, 20 micron pore, 60: 1 L/d, gain 4 x 106 Gain map, 33 mm ALD/borosilicate MCP pair, 20 micron pore, 60: 1 L/d, gain 4 x 106 MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Psec Timing Project (P. I. Henry Frisch, U. Chicago, Argonne - psec. uchicago. edu) Large area (200 x 200 mm) MCP image tubes for Cherenkov arrays and PET detectors Delayline readout, specialized ASICs Sub 10 ps time stamping (multiple photon) Sub mm imaging Thousands of tubes Inexpensive design MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

200 mm image tube Window with semitransparent photocathode Pair of microchannel plates Ceramic body with In seal Supports Stripline anode with signal pins MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Neutron MCPs (10 B or Gd doped) Absorption of Neutron Secondary(s) reach surface of pore Emission of photoelectron Electron gain above electronic threshold Similar to UV resolution MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Recent neutron imaging campaigns Paul Scherer Institute (PSI) Nuetra beam (thermal, 14% QE) ICON beam (cold, 43% QE) Oak Ridge National Laboratory Spallation Neutron Source (SNS) Ge. V Proton Linac into Hg target Pulsed source of neutrons at ~ 30 Hz Beamline 15 m long Time of Flight allows imaging neutron energy spectroscopy MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Portable MCP vacuum housing MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Gd Mask (thermal) Timepix TOT mode and event centroiding allows imaging with resolution down to the microchannel spacing of 11 m MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Neutron Radiography Optical Camera Thermal neutrons Cold neutrons MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Bullet neutron tomagraphy MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Strain analysis with Timepix Collect neutron events in Timing mode Shutter phased to initial pulse Record single event times and locations (X, Y, T) Covert time to energy (or wavelength) Save list of events Create data cube (3 D histogram) Fit Bragg edge to determine wavelength Plot edge location vs. position MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Bent steel screw Transmission (all energies) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Fe Bragg edge spectrum 2. 5 s bins and ~100 s edge width due to Hg target size. Green line is analytical fit MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Data cube (X, Y, E) Y E X MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Bragg edge mapping to measure strain MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Dynamic imaging of magnetic field with neutrons In collaboration with N. Kardjilov, M. Dawson, I. Manke, M. Strobl, HZB Berlin Magnetic field produced by 3 KHz AC current in a coil imaged 2 s time images stacked into a movie MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Concluding Remarks MCP detectors “in the field” demonstrate what can be done with an imaging photon/particle counting detectors. They are prevalent in the UV because of their historical QE advantage. Modern electronic techniques are expanding their niche applications, e. g. high rate TOF spectrometers/LIDAR New developments in optical/near IR photocathodes are pushing this technology to longer wavelengths. Other know weaknesses (lifetime, cost, etc. ) are being addressed with new materials and methods. There is still life in this old war-horse! MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Thank You I would like to acknowledge the support of the National Science Foundation National Institutes of Health National Institutes of Standards and Technology National Aeronautics and Space Administration under various contract and grant numbers. MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu

Aside: Timepix readout of APD arrays? Require gains of > 1000 but < 200000 Input pitch is 55µm 256 x 256 array Can cool CMOS chip to 77 K (but 1 W per chip is a high load) Cannot bias pixels separately Input takes holes or electrons, (can sink up to 10 n. A/pxl) MCP Detectors - DESY, Hamburg, June 2010 - John Vallerga, jvv@ssl. berkeley. edu