Presentation on theme: "High resolution imaging with MCP detectors using delay line anodes Ottmar Jagutzki, Uwe Spillmann, Achim Czasch Horst Schmidt-Böcking, Reinhard Dörner,"— Presentation transcript:
High resolution imaging with MCP detectors using delay line anodes Ottmar Jagutzki, Uwe Spillmann, Achim Czasch Horst Schmidt-Böcking, Reinhard Dörner, … In collaboration with Volker Dangendorf fromPTB Braunschweig, Neutron Radiography group
The helical wire delay-line anode Fast timing electronics high rate, multi-hit 5(7) electronic channels only easy read-out Center-of-mass averaging high position resolution time resolution: < 1 ns Sobottka and Williams 1988 DLD40 80 mm “Hexanode” delay-line detector (patented) Our typical resolution: 40-50 μm rms
Time-to-Digital-Converter: - (old) Wilkinson-type analog-digital conversion (like a TAC): high resolution but a slow digital conversion - “counter”-typefast (no!) conversion: resolution limited by clock rate Pretty high resolution and fast read-out TDC8HP: PC-controlled multi-hit TDC with 8 channels, 25 psec LSB, stable read-out speed: 400 kHz now, up to 2 MHz planned (< 10 ns dead-time between hits) “TDCHP” chip developed by CERN
How to detect visible/near-UV photons with that ?
Photek 75 mm image intensifier with RoentDek DL80 anode NASA test mask 0.15 mm FWHM 0.075 mm pixel (rms) Now: < 40 micron rms 5 mm grid constant, 1 mm obstacle
Counting/Imaging near-UV and visible photons with delay-line read-out DL40-PMT Quartz window Photo cathode MCP stack DL40 anode (or bigger) works fine, but - difficult to build - not very robust (?) - size up to 150 mm possible?
Counting/Imaging near-UV and visible photons with delay-line read-out via image charge pick-up: the RS-PMT Quartz window Photo cathode MCP stack Resistive screen pickup electrode (e.g. delay-line) Patented technique - easy, robust design of detector head - size up to 40 mm, may be bigger - standard (multi-layer) PCB pickup electrodes Image charge read-out: Battistoni et al. 1982
Counting/Imaging near-UV and visible photons with reconfigurable read-out Quartz window Photo cathode MCP stack Resistive screen other pickup electrodes: Wedge&Strip, Pixel,… Patented technique Read-out technique can easily be reconfigured using the same detector head.
Counting/Imaging VUV photons or particles with reconfigurable read-out “open RS-PMT” MCP stack Resistive screen pickup electrodes: Delay-line, Wedge&Strip, Pixel, … Patented technique Image charge read-out has some advantages over charge collection for some anodes: Beneficial even for open-face detectors
Delay-line read-out of RS-PMT: Multilayer PCB Front and rear side “antennas” (Eland 1994) connected to delay-line: (Berkeley group)LC-delay-line
LC-DL50 on open RS-PMT40, irradiated with α – particles, mesh obstacle 80 micron
LC-DL50 on open RS-PMT40, irradiated by ions with 500 kHz, mesh obstacle 80 micron
50 mm LC Hex-DL on a 4-layer PCB Hexanode for RS-PMT: - multi-hit (simultaneous photon pair detection is possible): Compton telescope? - intrinsic linearity correction (no test mask necessary): 3 combination for determining x- and y-coordinates from u, v, w coordinate system Example for x-layer: x = u = - (v + w) (over-determination) (vector addition) u vw x = u y = ( w - v ) /√3 But how can this help correcting non-linearity ?
Linearity correction of LC-delay-line: (no mask needed) of RS-PMT: 2,0 mm
Summary: - Large (open-face) MCP delay-line detector with up to 3000x3000 pixel - Resistive screen PMT or open MCP detector for counting photons (might qualify for space) - redundant triple-layer delay-line anode read-out with intrinsic linearity correction - read-out anodes can easily by swapped work to be done: - position resolution needs to be improved for the 40 mm and 25 mm formats - no experience with flight mission - not much experience with photon counting at all !
Applications: - FLIM (fluorescence life-time microscopy) - NEURRAD (element sensitive neutron radiography) in cooperation with Volker Dangendorf, PTB Braunschweig Thanks to Jürgen Barnstedt from Tübingen for borrowing us his RS-PMT! Object
Projection of grid mask 70/600micron, resolution 35 micron (1:700) Results of Barnstedt et al. (1998) 25mm RS-PMT (Proxitronic) - bi-alkali photo-cathode - 4-jaw Wedge&Strip anode