Nuclear Instruments and Methods in Physics Research A 580 (2007) 853–857 High spatial and temporal resolution photon/electron counting detector for synchrotron radiation research A.S. Tremsin a,Ã , G.V. Lebedev b , O.H.W. Siegmund a , J.V. Vallerga a , J.S. Hull a , J.B. McPhate a , C. Jozwiak b , Y. Chen b , J.H. Guo b , Z.X. Shen c , Z. Hussain b a Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA 94720, USA b Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA c Applied Physics and Stanford Synchrotron Radiation Laboratory, Department of Physics, Stanford University, Stanford, CA 94305, USA Available online 5 July 2007 Abstract This paper reports on the development of a high resolution electron/photon/ion imaging system which detects events with a timing accuracy of o160 ps FWHM and a two-dimensional spatial accuracy of 50 mm FWHM. The event counting detector uses microchannel plates for signal amplification and can sustain counting rates exceeding 1.5 MHz for evenly distributed events (0.4 MHz with 10% dead time for randomly distributed events). The detector combined with a time-of-flight angular resolved photoelectron energy analyzer was tested at a synchrotron beamline. The results of these measurements illustrate the unique capabilities of the analytical system, allowing simultaneous imaging of photoelectrons in momentum space and measurement of the energy spectrum, as well as filtering the data in user defined temporal and/or spatial windows. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.n; 07.85.Qe; 07.77.n Keywords: Event counting detectors; High spatial and temporal resolution; Synchrotron instrumentation 1. Introduction In addition to high brightness, excellent spectral resolu- tion, broad tunability and polarization control, synchro- tron sources provide short time (o100 ps) pulsed radiation, enabling a number of unique experimental techniques. The ability to register simultaneously not only timing but also spatial information for synchrotron excited photons, electrons, or ions allows new studies to be done that were not previously feasible. One of the key elements of such an experimental system is a high temporal (sub-nanosecond) and spatial resolution detector. Recently, there has been rapid progress in development of position sensitive event counting devices based on microchannel plate (MCP) technology, primarily developed for astrophysical applica- tions [1–3]. All the advances of this new generation of detectors can now be successfully implemented in synchro- tron beamline instrumentation. The two-dimensional spatial resolution of these detectors can be as low as o15 mm FWHM [4] with a timing accuracy of photon/ electron/ion detection less than 150 ps. Another attractive feature of MCP detectors is their very low dark count rate (o0.1 counts cm 2 s 1 ). These devices can be built with active areas exceeding 6 cm in diameter and can have high detection efficiencies to X-ray and UV photons and especially to charged particles. The detection can be configured to be insensitive to positive or negative particles by the application of retarding meshes, allowing signal differentiation at the plane of the detector. One of the previous limitations of MCP technology was relatively low counting rate capabilities, not exceeding 100 kHz. The rapid developments in event encoding electronics have led to substantial improvement in the speed of signal processing, allowing event detection with counting rates exceeding 1 MHz. ARTICLE IN PRESS www.elsevier.com/locate/nima 0168-9002/$ - see front matter r 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2007.06.085 Ã Corresponding author. E-mail address: ast@ssl.berkeley.edu (A.S. Tremsin).