Pixelated LGADs have been established as the baseline technology for timing detectors for the High Granularity Timing Detector (HGTD) and the Endcap Timing Layer (ETL) of the ATLAS and CMS experiments, respectively. The drawback of segmenting an LGAD is the non-gain area present between pixels and the consequent reduction in the fill factor. To overcome this issue, the inverse LGAD (iLGAD) technology has been proposed by IMB-CNM to enhance the fill factor and provide excellent tracking capabilities. In this work, we explore the use of iLGAD sensors for surface damage irradiation by developing a new generation of iLGADs, the periphery of which is optimized to improve the performance of irradiated sensors. The fabricated iLGAD sensors exhibit good electrical performances before and after X-ray irradiation.

The design of pixel-based tracking detectors for a Low Q2 Tagger in the Far Backward region of the ePIC detector at EIC is presented. The physics case is outlined, together with estimates of rates and resolutions, and the current design based on Timepix4 technology is introduced.

In the last few years, Low Gain Avalanche Detectors (LGAD) have demonstrated their outstanding performance when detecting high-energy charged particles. However, due to the difference in the multiplication mechanism for holes and electrons, the detection performance for low penetrating particles (e.g low-energy protons or soft x-rays) is significantly reduced. A novel design of an LGAD detector, the NLGAD, was designed and fabricated at CNM to overcome this drawback. A qualitative description of the NLGAD concept is presented in this work, along with gain response measurements of the first prototypes under visible light of 660 nm and 15 keV x-rays. Additionally, a review of the gain response under visible light of 404 nm and IR light of 1064 nm, previously studied, is also evaluated in this work. The results demonstrate that the NLGAD concept has the potential to detect low penetrating particles.

Hybrid pixel detectors (HPDs) have been shown to be highly effective for diffraction-based and time-resolved studies in transmission electron microscopy, but their performance is limited by the fact that high-energy electrons scatter over long distances in their thick Si sensors. An advantage of HPDs compared to monolithic active pixel sensors (MAPS) is that their sensor does not need to be fabricated from Si. We have compared the performance of the Medipix3 HPD with a Si sensor and with a GaAs:Cr sensor using primary electrons in the energy range of 60 - 300keV. We describe the measurement and calculation of the detectors' modulation transfer function (MTF) and detective quantum efficiency (DQE), which show that the performance of the GaAs:Cr device is markedly superior to that of the Si device for high-energy electrons.

We present the design and application of a 64 x 64 pixel SPAD array to portable colorimetric sensing, and fluorescence and x-ray imaging. The device was fabricated on an unmodified 180 nm CMOS process and is based on a square p+/n active junction SPAD geometry suitable for detecting green fluorescence emission. The stand-alone SPAD shows a photodetection probability greater than 60% at 5 V excess bias, with a dark count rate of less than 4 cps/mu m(2) and sub-ns timing jitter performance. It has a global shutter with an in-pixel 8-hit counter; four 5-bit decoders and two 64-to-1 multiplexer blocks allow the data to be read-out. The array of sensors was able to detect fluorescence from a fluorescein isothiocyanate (FITC) solution down to a concentration of 900 pM with an SNR of 9.8 dB. A colorimetric assay was performed on top of the sensor array with a limit of quantification of 3.1 mu m. X-rays images, using energies ranging from 10 kVp to 100 kVp, of a lead grating mask were acquired without using a scintillation crystal.

A square shaped, low noise and high photo-response single photon avalanche diode suitable for circuit integration, implemented in a standard CMOS 180 nm high voltage technology, is presented. In this work, a p+ to shallow n-well junction was engineered with a very smooth electric field profile guard ring to attain a photo detection probability peak higher than 50% with a median dark count rate lower than 2 Hz/μm 2 when operated at an excess bias of 4 V. The reported timing jitter full width at half maximum is below 300 ps for 640 nm laser pulses.

Monolithic CMOS sensors are being proposed for the upgrade of the ATLAS inner tracker. Sensors fabricated in a new TowerJazz 180nm process, feature full depletion of the sensitive layer and radiation tolerance up to 10(15) n(eq)/cm(2).

We demonstrate the use of the miniaturised Medipix positron sensor for detection of the clinical PET radiotracer, [(68)Ga]gallium-citrate, on a silica-based monolith, towards microfluidic quality control. The system achieved a far superior signal-to-noise ratio compared to conventional sodium iodide-based radio-HPLC detection and allowed real-time visualisation of positrons in the monolith.

The application of differential phase contrast imaging to the study of polycrystalline magnetic thin films and nanostructures has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In this paper we demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected scanning transmission electron microscopy (STEM) and subsequent processing of the acquired data allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. We show that this allows subpixel measurement of the beam deflection due to the magnetic induction. While the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging.

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A prototype particle tracking telescope was constructed using Timepix and Medipix ASIC hybrid pixel assemblies as the six sensing planes. Each telescope plane consisted of one 1.4cm2 assembly, providing a 256 ×256 array of 55μm square pixels. The telescope achieved a pointing resolution of 2.4μm at the position of the device under test. During a beam test in 2009 the telescope was used to evaluate in detail the performance of two Timepix hybrid pixel assemblies; a standard planar 300μm thick sensor, and 285μm thick double sided 3D sensor. This paper describes a charge calibration study of the pixel devices, which allows the true charge to be extracted, and reports on measurements of the charge collection characteristics and Landau distributions. The planar sensor achieved a best resolution of 4.0±0.1μm for angled tracks, and resolutions of between 4.4 and 11μm for perpendicular tracks, depending on the applied bias voltage. The double sided 3D sensor, which has significantly less charge sharing, was found to have an optimal resolution of 9.0±0.1μm for angled tracks, and a resolution of 16.0±0.2μm for perpendicular tracks. Based on these studies it is concluded that the Timepix ASIC shows an excellent performance when used as a device for charged particle tracking.

Alpha particles can be used as a test stimulus offering several advantages for probing materials of micrometre thicknesses. In this work a silicon CMOS Active Pixel Sensor (APS) is evaluated for alpha particle detection and imaging. These devices can replace traditionally used solid-state track detectors, giving advantages of increased sensitivity, improved linearity and higher dynamic range. CMOS APSs offer high detection efficiency, low noise and digital readout. Qualitative and quantitative analysis of the back-illuminated back-thinned (BT) and standard sensor response to 5.5MeV alpha particles is presented. Alpha particle detection efficiency was estimated and energy resolution was measured. Imaging capabilities were assessed and quantified. Cluster centroiding algorithms were implemented for image quality improvement.

The radiation produced when an intense laser interacts with a solid target could provide a cheaper source of X-rays to synchrotrons and free-electron lasers. But they can also produce short bursts of gamma rays, whereas synchrotrons do not. An intense laser pulse in a plasma can accelerate electrons1,2,3,4 to GeV energies in centimetres5,6,7. Transverse betatron motion8,9 in the plasma wake results in X-ray photons with an energy that depends on the electron energy, oscillation amplitude and frequency of the betatron motion10,11,12. Betatron X-rays from laser-accelerator electrons have hitherto been limited to spectra peaking between 1 and 10 keV (ref. 13). Here we show that the betatron amplitude is resonantly enhanced when electrons interact with the rear of the laser pulse14,15. At high electron energy, resonance occurs when the laser frequency is a harmonic of the betatron frequency, leading to a significant increase in the photon energy. 108 gamma-ray photons, with spectra peaking between 20 and 150 keV, and a peak brilliance >1023 photons s−1 mrad−2 mm−2 per 0.1% bandwidth, are measured for 700 MeV beams, with 107 photons emitted between 1 and 7 MeV. Femtosecond duration gamma-rays may find uses in imaging, isotope production, probing dense matter, homeland security and nuclear physics16.

A need exists for high-speed single-photon counting optical imaging detectors. Single-photon counting high-speed detection of x rays is possible by using Medipix2 with pixelated silicon photodiodes. In this article, we report on a device that exploits the Medipix2 chip for optical imaging. The fabricated device is capable of imaging at >3000 frames/s over a 256×256 pixel matrix. The imaging performance of the detector device via the modulation transfer function is measured, and the presence of ion feedback and its degradation of the imaging properties are discussed.

A series of tests in CERN’s North Area beam facility have been used to demonstrate the suitability of the Timepix chip, combined with a silicon sensor, as a particle tracking device. Specifically of interest is the potential of a successor to the current chip to be used in the context of an LHCb VELO upgrade. The 55mm square pixels, large active fraction and analogue information make the chip very attractive for forward, high precision tracking systems such as the VELO. In this contribution preliminary results are presented showing the resolution achieved by a Timepix assembly in a 120GeV p beam, over a wide range of incident angles. At the optimum angle the detector was able to provide an unbiased track residual of 5.5mm. The telescope constructed for these measurements contributed a track extrapolation error of 2.5mm. The plans for a future development of this telescope, also based on Timepix assemblies are discussed, with proposals for upgrading its spatial and timing resolution.

We present a novel complementary metal-oxide-semiconductor (CMOS) active-pixel sensor imager that incorporates different reset schemes to achieve lower reset noise levels. The sensor, eLeNA, features a 448 x 512 array with a pixel pitch of 15 mu m, fabricated using a 0.18-mu m CMOS process. Fourteen sections and five different reset methods were employed. Without using pinned diodes, we implanted structures for correlated double sampling. A noise of 6 e- is measured with a conversion gain of 49 mu V/e-. We will discuss various applications for the reset method that achieved the best overall performance, considering leakage current and read noise.

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) Collaboration has been developing Column-Parallel CCDs for the vertex detector of a future Linear Collider which can be read out many times faster than standard CCDs. The most recent studies are of devices designed to reduce both the CCD's intergate capacitance and the clock voltages necessary to drive it. A comparative study of measured Charge Transfer Inefficiency values between our previous and new results for a range of operating temperatures is presented.

Progress in the development of neutron imaging facilities requires more sophisticated and advanced tools for high resolution and efficient neutron detection. This paper reports on the evaluation of CMOS Monolithic Active Pixel Sensor (MAPS) technology as a neutron detector. The sensor HEPAPS4, which was originally designed for high energy physics applications, was coated with two types of conversion material. The 6LiF converter is suitable for the detecting thermal neutrons, while the polyethylene converter is used for the tracking fast neutrons. The results showed that such a technology is suitable for the detection of both fast and thermal neutrons.