To detect tracks of charged particles close to the interaction point in high energy physics experiments of the next generation colliders, hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors as well as the BTeV detector at the Tevatron will use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh radiation environment at the LHC for its full life time and without severe compromises in performance. From these developments a number of different applications have spun off, most notably for biomedical imaging. Beyond hybrid pixels, a number of trends and possibilities with yet improved performance in some aspects have appeared and presently developed to greater maturity. Among them are monolithic or semi-monolithic pixel detectors which do not require complicated hybridization but come as single sensor/IC entities. The present state in hybrid pixel detector development for the LHC experiments as well as for some imaging applications is reviewed and new trends towards monolithic or semi-monolithic pixel devices are summarized.
The Argonne Pixel Tracking Telescope is installed at the Fermilab Test Beam Facility. The telescope consists of six planar n^{+}-in-n silicon sensors with a pixel size of 250 {\times} 50 μm^{2}. The instrumentation of the telescope is described including the electrical and mechanical setups. A 120 GeV proton beam is used to evaluate the telescope performance using criteria such as the cluster size, pixel tracking efficiency, and spatial resolution. The spatial resolution of the telescope is measured to be 72 μm {\times} 13 μm.
A prototype of the CMOS pixel sensor named SUPIX-1 has been fabricated and tested in order to investigate the feasibility of a pixelated tracker for a proposed Higgs factory, namely, the Circular Electron-Positron Collider (CEPC). The sensor, taped out with a 180 nm CMOS Image Sensor (CIS) process, consists of nine different pixel arrays varying in pixel pitches, diode sizes and geometries in order to study the particle detection performance of enlarged pixels. The test was carried out with a Fe-55 radioactive source. Two soft X-ray peaks observed were used to calibrate the charge to voltage f…
The High Luminosity upgrade of the CERN Large Hadron Collider will be able to reach a peak instantaneous luminosity of 5E34/cm2 s. The innermost detectors of the CMS and ATLAS experiments will have to cope with unprecedented requirements on radiation hardness. At the end of the operation period, radiation levels are expected to reach values above 2.6E16 neq/cm2. Sensors based on 3D pixel technology, with intrinsic radiation tolerance, are the baseline option for the innermost layers of the vertex detectors of several HL-LHC experiments. This article gives an overview of the ongoing characteriz…
Silicon tracking detectors can record the charge in each channel (analog or digitized) or have only binary readout (hit or no hit). While there is significant literature on the position resolution obtained from interpolation of charge measurements, a comprehensive study of the resolution obtainable with binary readout is lacking. It is commonly assumed that the binary resolution is $\text{pitch}/\sqrt{12}$, but this is generally a worst case upper limit. In this paper we study, using simulation, the best achievable resolution for minimum ionizing particles in binary readout pixels. A wide rang…
The physics aims at the proposed high-energy $e^+e^-$ collider CLIC pose challenging demands on the performance of the detector system. Precise hit-time tagging, an excellent spatial resolutions, and a low mass are required for the vertex and tracking detectors. To meet these requirements, an all-silicon vertex and tracking detector system is foreseen, for which a broad R&D programme on a variety of novel silicon detector technologies is being pursued. For the ultra-low mass vertex detector, different hybrid technologies with innovative sensor concepts and interconnection techniques are explor…
We present the first characterization results of Timespot1, an ASIC designed in CMOS 28 nm technology, featuring a $32 \times 32$ pixel matrix with a pitch of $55 ~ μm$. Timespot1 is the first small-size prototype, conceived to readout fine-pitch pixels with single-hit time resolution below $50 ~ ps_\text{rms}$ and input rates of several hundreds of kilohertz per pixel. Such experimental conditions will be typical of the next generation of high-luminosity collider experiments, from the LHC run5 and beyond. Each pixel of the ASIC includes a charge amplifier, a discriminator, and a Time-to-Digit…
The primary secondary particles from the spallation target of the China Spallation Neutron Source are mainly gammas and neutrons, which are related to the distribution of the incident proton. The reconstruction of proton beam spot could be implemented based on the distribution of secondary particles. The methods of pinhole imaging and Compton imaging are developed by measuring the gamma distribution based on the pixelated detector. The secondary gammas could be detected by the pixelated gamma detector directly. The neutron can be identified by detecting the characteristic (478 keV) $γ$-rays fr…
A high spatial resolution tracking system was setup with the Micro-mesh gaseous structure (Micromegas) detectors in order to study the muon tomographic imaging technique for nuclear threat detection. 6 layers of 90 mm $\times$ 90 mm one-dimensional readout Micromegas were used to construct a tracking system and the imaging test using some metallic bars was performed with cosmic ray muons. A two-dimensional imaging of the test object was presented with a newly proposed ratio algorithm.
The ALICE Experiment has replaced its Inner Tracking System with a 7-layer pixel-only tracker made out of more than 24000 monolithic active pixel sensor chips, in order to fulfill the requirements of the physics program of the LHC Run 3. The upgraded Inner Tracking System (ITS2) has been installed in the ALICE experiment during the LHC long shutdown 2 and has started to take data with the beginning of Run 3 in July 2022, with proton-proton collisions at $\sqrt{s}$ = 13.6 TeV. With its 12.5 billion pixels it is the largest pixel detector installed in a high energy physics experiment to date. To…
We developed a beam telescope system comprising five layers of 300-$μ$m-thick INTPIX4NA monolithic pixel sensors with each pixel size of 17 $μ$m square. The sensors were fabricated using silicon-on-insulator (SOI) technology. The signal-to-noise ratio of 140--230 is realized at a bias voltage of 20~V. The tracker system was tested using a positron beam of 200--822 MeV/c, and various tracking methods are examined to optimize spatial precision achievable at these energies. The best tracking precision including the precision of the sensor under test itself is 11.04 $\pm$ 0.10 $μ$m for 822-MeV/c p…
Single Photon Counting X-ray Imaging with Si and CdTe Single Chip Pixel Detectors and Multichip Pixel Modules
多芯片模块（MCM）与4个单光子计数MPEC 2.3芯片凸块键合到1.3厘米× 1.3厘米的大碲化镉和硅半导体传感器，以及单芯片像素探测器已成功地建立和运行。MPEC 2.3芯片提供高达1 MHz的像素计数速率、18位的大动态范围、2个计数器和具有连续可调阈值的能量窗口。每个MPEC具有200 um x 200 um像素大小的32 x 32像素。对于MCM，4个芯片被布置在2 x 2阵列中，这导致64 x 64传感器像素几何形状。的MCM结构进行了描述，并显示了不同的探测器的成像性能。作为读出系统，一个新开发的USB系统已被使用。
We have developed a neutron imaging sensor based on an INTPIX4-SOI pixelated silicon device. Neutron irradiation tests are performed at several neutron facilities to investigate sensor's responses for neutrons. Detection efficiency is measured to be around $1.5$\% for thermal neutrons. Upper bound of spatial resolution is evaluated to be $4.1 \pm 0.2 ~μ$m in terms of a standard deviation of the line spread function.
A hard x-ray, high-speed, high dynamic range scientific x-ray imager is described. The imager is based on the mixed-mode pixel array detector (MM-PAD) readout chip coupled to a 750 micron thick cadmium telluride (CdTe) sensor. The full imager is a 2 x 3 tiled array of MM-PAD sensor/readout chip hybrids. CdTe improves detection for high energy x-rays as compared to silicon sensors, enabling efficient x-ray imaging to extend to >100 keV. The detector is capable of 1 kHz imaging and in-pixel circuitry has been designed to allow for well depths of greater than 4 x 10^{6} 80 keV x-rays. A charge in…
Chromatic X-Ray imaging with a fine pitch CdTe sensor coupled to a large area photon counting pixel ASIC
提出了一种具有数字特性的新型X射线成像传感器。它基于彩色光子计数技术。探测器能够单独计数入射的X射线光子，并根据它们的能量将它们分离（每次曝光两个“彩色”图像）。能量选择以射线照相成像速度（GHz全局计数率）实时进行。光子计数、彩色模式和极高的空间分辨率（超过10 l. p./ mm，MTF 50）允许获得图像质量和吸收剂量之间的最佳比率。成像系统的单独块是由薄像素化CdTe晶体（传感器）耦合到大面积VLSI CMOS像素ASIC制成的双面可对接半导体辐射检测器。已建成1、2、4、8个瓦片单元。8块单元具有25 cm x 2.5cm的敏感区域。结果和图像从深入测试的几种配置的系统。X射线成像系统是PIXIRAD成像计数器s.r.l.的技术平台，最近成立的INFN分拆公司。
High-rate, high-resolution single photon X-ray imaging: Medipix4, a large 4-side buttable pixel readout chip with high granularity and spectroscopic capabilities
介绍了一种基于$200~nm$ SOI CMOS工艺的新型单片SOI像素传感器的设计。所提出的像素探测器的主要应用是光谱学，但它也可以用于粒子物理实验中的最小电离粒子（MIP）跟踪。出于这个原因，开发了几种不同版本的像素单元：基于源极跟随器的像素用于跟踪，具有用于光谱的低噪声像素，以及用于时间和幅度测量的自触发像素。此外，本文还介绍了一种逐次逼近型模数转换器（SARADC）的设计。一个10位SAR ADC被开发用于光谱测量，一个较低分辨率的6位SAR ADC被集成在像素矩阵中作为列ADC，用于跟踪应用。
Proton Computed Tomography (CT) is a prototype imaging modality for the reconstruction of the Relative Stopping Power of a patient, for more accurate calculations of the dose distributions in proton therapy dose planning. The measurements needed for the reconstruction of a proton CT image are: i) each initial proton vector incident on the imaged object, ii) each proton vector incident on the front face of the detector and iii) the stopping depth of each proton in the detector. In this study, a track reconstruction algorithm is adapted for a planned pixel-based particle-tracking range telescope…
A CMOS pixel sensor, named Supix-1, is developed for a pixelated silicon tracker for the Circular Electron-Positron Collider (CEPC) project. The sensor, consisted of nine sectors varying in pixel sizes, diode sizes and geometries, is fabricated with a 180 nm CMOS Image Sensor (CIS) process to study the particle detection performance of enlarged pixels. In this work, the radiation-induced effects on the charge collection of the sensor under the fluence of 1 $\times$ 10^13 1 MeV neq/cm^2 are studied by the measurements with the radioactive source of Fe-55 and the Technology Computer Aided Design…
The Topmetal-M is a large area pixel sensor (18 mm * 23 mm) prototype fabricated in a new 130 nm high-resistivity CMOS process in 2019. It contains 400 rows * 512 columns square pixels with the pitch of 40 μm. In Topmetal-M, a novel charge collection method combing the Monolithic Active Pixel Sensor (MAPS) and the Topmetal sensor has been proposed for the first time. Both the ionized charge deposited by the particle in the sensor and along the track over the sensor can be collected. The in-pixel circuit mainly consists of a low-noise charge sensitive amplifier to establish the signal for the e…
The basic principle of operation of silicon sensors with resistive read-out is built-in charge sharing. Resistive Silicon Detectors (RSD, also known as AC-LGAD), exploiting the signals seen on the electrodes surrounding the impact point, achieve excellent space and time resolutions even with very large pixels. In this paper, a TCT system using a 1064 nm picosecond laser is used to characterize sensors from the second RSD production at the Fondazione Bruno Kessler. The paper first introduces the parametrization of the errors in the determination of the position and time coordinates in RSD, then…
The entire tracking system of the ATLAS experiment will be replaced during the LHC Phase-II shutdown. A new silicon Inner Tracker (ITk) will contain five pixel layers equipped with new sensors and readout electronics capable to improve the tracking performance, cope with the high particle multiplicity and work in a high-luminosity environment. In order to standardize modules of the Inner Tracker, the idea of a common hybrid pixel module was introduced to be used in all regions of the detector. The common hybrid module assembly and testing techniques will be presented. The module construction, …
This is part of a document, which is devoted to the developments of pixel detectors in the context of the International Linear Collider. From the early developments of the MIMOSAs to the proposed DotPix I recall some of the major progresses. The need for very precise vertex reconstruction is the reason for the Research and Development of new pixel detectors, first derived from the CMOS sensors and in further steps with new semiconductors structures. The problem of radiation effects was investigated and this is the case for the noise level with emphasis of the benefits of downscaling. Specific …
The phase 1 upgrade of the CMS pixel detector has been designed to maintain the tracking performance at instantaneous luminosities of $2 \times 10^{34} \mathrm{~cm}^{-2} \mathrm{~s}^{-1}$. Both barrel and endcap disk systems now feature one extra layer (4 barrel layers and 3 endcap disks), and a digital readout that provides a large enough bandwidth to read out its 124M pixel channels (87.7 percent more pixels compared to the previous system). The backend control and readout systems have been upgraded accordingly from VME-based to micro-TCA-based ones. The detector is now also equipped with a …
Single-pixel imaging is suitable for low light level scenarios because a bucket detector is employed to maximally collect the light from an object. However, one of the challenges is its slow imaging speed, mainly due to the slow light modulation technique. We here demonstrate 1.4MHz video imaging based on computational ghost imaging with a RGB LED array having a full-range frame rate up to 100MHz. With this method, the motion of a high speed propeller is observed. Moreover, by exploiting single-photon detectors to increase the detection efficiency, this method is developed for ultra-high-speed…
With the proliferation of inexpensive CMOS cameras, medical imaging experiences a noticeable influx of new technologies. While anatomical imaging is based on well-established principles of photography, physiological optical imaging is a relatively novel range of technologies that requires considering a new set of technical and physiological aspects. We discuss several factors (binning, spatial frequency sampling, and distance to the target area) indispensable to getting quantifiable and reproducible results, which are the essence of physiological imaging. We also discussed their implications f…
An extensive comparison of the path uncertainty in single particle tracking systems for ion imaging was carried out based on Monte Carlo simulations. The spatial resolution as function of system parameters such as geometry, detector properties and the energy of proton and helium beams was investigated to serve as a guideline for hardware developments. Primary particle paths were sampled within a water volume and compared to the most likely path estimate obtained from detector measurements, yielding a depth-dependent uncertainty envelope. The maximum uncertainty along this curve was converted t…
We have been developing monolithic active pixel sensors, named ``XRPIX'', based on the silicon-on-insulator (SOI) pixel technology for future X-ray astronomy satellites. XRPIX has the function of event trigger and hit address outputs. This function allows us to read out analog signals only of hit pixels on trigger timing, which is referred to as the event-driven readout mode. Recently, we processed ``XRPIX5b'' with the largest imaging area of 21.9~mm $\times$ 13.8~mm in the XRPIX series. X-ray spectra are successfully obtained from all the pixels, and the readout noise is 46~e$^-$~(rms) in the…
