High spatial and temporal resolution photon/electron counting detector for synchrotron radiation research
Introduction
In addition to high brightness, excellent spectral resolution, broad tunability and polarization control, synchrotron sources provide short time (<100 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 applications [1], [2], [3]. All the advances of this new generation of detectors can now be successfully implemented in synchrotron beamline instrumentation. The two-dimensional spatial resolution of these detectors can be as low as <15 μm 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 (<0.1 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.
In this paper we demonstrate the unique experimental capabilities of an MCP detection system used in a Time-of-Flight (TOF) based Angle Resolved Photoemission Spectrometer which is being built at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL).
Section snippets
Position and time sensitive event counting detector
The position sensitive detector used in the experiments has a 25 mm diameter active area and includes an MCP stack consisting of three 60:1 (L/D), 33 mm diameter MCPs with 12 μm pores and 13° pore bias, Fig. 1, Fig. 2. The event positional encoding is performed by a Cross Delay Line (XDL) anode capacitively coupled to the processing electronics (Fig. 1), allowing independent control of all the voltages on the detector. The latter fact provides the possibility to vary the potential on the detector
Results and discussion
The results of the experiments described below should only be considered as an illustration of the capabilities of the detection system rather than the ultimate performance of the ARPES system under construction and should not be used for the interpretation of physical phenomena.
As mentioned earlier, the detection system is capable of differentiation between photon and charged particle (electrons in our case) events by either event timing or by potentials applied to the detector. The two images
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Cited by (15)
Unique capabilities and applications of Microchannel Plate (MCP) detectors with Medipix/Timepix readout
2020, Radiation MeasurementsCitation Excerpt :In this paper we demonstrate few novel capabilities provided by the combination of MCP amplifier and Medipix/Timepix pixelated readout, enabling event counting of low energy particles at high input fluxes, sometimes with many of them arriving nearly simultaneously. Low noise photon counting with MCP detectors has been widely used in many applications ranging from Astrophysical instrumentation (Fraser, 2001), (Siegmund et al., 2004), to soft X-ray synchrotron instrumentation (Tremsin et al., 2007), to biological imaging (Michalet et al., 1611), (Hirvonen et al., 2017) and many others. For the detection of visible light photons microchannel plate photomultiplier tubes (MCP-PMT) are used where various types of readout are enclosed into a sealed vacuum tube.
Optimization of high count rate event counting detector with Microchannel Plates and quad Timepix readout
2015, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentCitation Excerpt :The low noise of the Timepix readout allows operation at MCP gains as low as 104–105, substantially improving its counting rate capabilities and extending the lifetime of the detector. The high resolution photon/ion/electron/neutron counting capabilities of Microchannel Plate (MCP) detectors have been demonstrated previously with several readout technologies to timing resolution of ~10 ps and spatial resolution limited by the present commercial MCP pore geometry (~5–10 µm) [2–5]. The unique feature of an MCP electron amplifier is to provide gains in excess of 107 per event while preserving the location within a single pore.
Detection efficiency, spatial and timing resolution of thermal and cold neutron counting MCP detectors
2009, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentCharacterisation of a detector based on microchannel plates for electrons in the energy range 10-20 keV
2008, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentA two-dimensional detector for pump-and-probe and time resolved experiments
2008, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentHigh-resolution detection system for time-of-flight electron spectrometry
2007, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment