Development of EM-CCD-based X-ray detector for synchrotron applications

A high speed, low noise camera system for crystallography and X-ray imaging applications is developed and successfully demonstrated. By coupling an electron-multiplying (EM)-CCD to a 3:1 fibre-optic taper and a CsI(Tl) scintillator, it was possible to detect hard X-rays. This novel approach to hard X-ray imaging takes advantage of sub-electron equivalent readout noise performance at high pixel readout frequencies of EM-CCD detectors with the increase in the imaging area that is offered through the use of a fibre-optic taper. Compared with the industry state of the art, based on CCD camera systems, a high frame rate for a full-frame readout (50 ms) and a lower readout noise (<1 electron root mean square) across a range of X-ray energies (6–18 keV) were achieved

Ageing and proton irradiation damage of a low voltage EMCCD in a CMOS process

Electron Multiplying Charge Coupled Devices (EMCCDs) have revolutionised low light level imaging, providing highly sensitive detection capabilities. Implementing Electron Multiplication (EM) in Charge Coupled Devices (CCDs) can increase the Signal to Noise Ratio (SNR) and lead to further developments in low light level applications such as improvements in image contrast and single photon imaging. Demand has grown for EMCCD devices with properties traditionally restricted to Complementary Metal-Oxide-Semiconductor (CMOS) image sensors, such as lower power consumption and higher radiation tolerance. However, EMCCDs are known to experience an ageing effect, such that the gain gradually decreases with time. This paper presents results detailing EM ageing in an Electron Multiplying Complementary Metal-Oxide-Semiconductor (EMCMOS) device and its effect on several device characteristics such as Charge Transfer Inefficiency (CTI) and thermal dark signal. When operated at room temperature an average decrease in gain of over 20% after an operational period of 175 hours was detected. With many image sensors deployed in harsh radiation environments, the radiation hardness of the device following proton irradiation was also tested. This paper presents the results of a proton irradiation completed at the Paul Scherrer Institut (PSI) at a 10 MeV equivalent fluence of 4.15 × 1010 protons/cm2. The pre-irradiation characterisation, irradiation methodology and post-irradiation results are detailed, demonstrating an increase in dark current and a decrease in its activation energy. Finally, this paper presents a comparison of the damage caused by EM gain ageing and proton irradiation

Novel method for identifying the cause of inherent ageing in Electron Multiplying Charge Coupled Devices

The charge multiplication process used in the Electron Multiplying CCD (EMCCD) is subject to an ageing effect in which the gain achieved at particular avalanche potentials, gradually decreases during operation. To utilise these devices for both space and terrestrial applications where recalibration of the gain is not feasible, a comprehensive understanding of the ageing process is required. A custom automated test equipment (ATE) has been produced and used to develop the techniques required for investigating the ageing process alongside the verification of simulation work on the subject. Simulation work carried out by e2v technologies has suggested hole build-up at the Si/Si02 interface below one of the transfer gates. This build up of holes has now been linked with a reduction in avalanche potential in the device. A novel experimental technique has therefore been developed to determine the actual potentials within the device and thereby determine the validity of this prediction. The initial results tend to support simulation as an increase in the potential beneath one of the phases is observed

Comparison of EM-CCD and scientific CMOS based camera systems for high resolution X-ray imaging and tomography applications

We have developed an Electron Multiplying (EM) CCD based, high frame rate camera system using an optical lens system for X-ray imaging and tomography. The current state of the art systems generally use scientific CMOS sensors that have a readout noise of a few electrons and operate at high frame rates. Through the use of electron multiplication, the EM-CCD camera is able to operate with a sub-electron equivalent readout noise and a frame rate of up to 50 HZ (full-frame). The EM-CCD-based camera system has a major advantage over existing technology in that it has a high signal-to-noise ratio even at very low signal levels. This allows radiation-sensitive samples to be analysed with low flux X-ray beams which greatly reduces the beam damage. This paper shows that under the conditions of this experiment the EM-CCD camera system has a comparable spatial resolution performance to the scientific CMOS based imaging system and has a superior signal-to-noise ratio

LUVMI-X: A Versatile Platform for Resource Prospecting on the Moon

Our current knowledge about the Moon's resource potential is limited to remote-sensing measurements and the analysis of Apollo-era samples. Even though there are persistent indications for substantial deposits of water and other volatiles-especially in the lunar polar regions-high-resolution mapping and in-situ measurements are required to assess the technical feasibility and economic viability of exploiting them. The LUVMI-X mission will use a 50-kg rover equipped with complementary instrumentation to prospect illuminated and shadowed areas in the Moon's polar regions through the use of laser spectroscopy, neutron spectroscopy, and direct sampling in combination with mass spectroscopy. It will also analyze the regolith composition and characterize the surface radiation environment

How Fragmentation Can Improve Co-ordination: Setting Standards in International Telecommunications

There is a stark contrast between the way industrial economics asks us to think about standard setting in telecommunications and the way standard-setting is actually organized. On the one hand, leading scholars maintain that standard setting is a natural monopoly. On the other hand, the number of standards organizations for telecommunications is quite large and there is no indication that this number will decrease. The paper analyzes how to resolve this discrep ancy. It argues that there are reasons to believe that the natural monopoly hypothesis is wrong. Under a certain set of conditions which are prevalent in international telecommunications, the distribution of standard setting to a multitude of competing standards organizations is both stable and efficient