Material Budget Research Articles

Dark Count Rate Degradation in CMOS SPADs Exposed to X-Rays and Neutrons

Single-photon avalanche diode (SPAD) arrays fabricated in a 180-nm CMOS technology with a high-voltage option have been exposed to calibrated neutron and X-ray sources to evaluate their radiation tolerance. The technology is being investigated in view of the design of low material budget detectors for charged particle tracking based on the coincidence of the signals coming from two or more overlapping layers of SPAD sensors. Each element in the array is a monolithic detector including the processing electronics together with the diode in the same substrate. Different sensor dimensions and structures have been implemented in the test chip to thoroughly explore the technology features. This paper will present and discuss the results from the characterization, in terms of dark count rate, of SPAD arrays irradiated with X-ray doses reaching 1 Mrad(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and with neutron fluences up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> 1-MeV neutron equivalent cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> .

Response of river water chemistry to changing atmospheric environment and sulfur dynamics in a forested catchment in central Japan

Reduction of atmospheric sulfur (S) deposition and recovery of terrestrial ecosystems from acidification are matters of concerns in Asia. The Lake Ijira catchment (IJR) is located in the downwind region of the Chukyo Industrial Area in central Japan and has historically experienced large-scale deposition of S and nitrogen (N) from the atmosphere. Long-term monitoring data on the river water (RW) chemistry since 1988 were assessed with intensive-survey datasets on the input–output material budgets and S isotopic analysis (δ34S). Previous studies have suggested that IJR was acidified and N-saturated, which was triggered by climatic anomalies (cold summer and drought summer) in the mid-1990s. Analysis shows that with a decline in \( {\text{NO}}_{3}^{ - } \) concentrations, RW pH recovered to its original level in the early 2000s. Reductions in atmospheric deposition, diminished effects of climatic anomalies, and forest management practices, have all contributed to RW chemistry recovery. Although the \( {\text{SO}}_{4}^{2 - } \) concentration in the RW has declined continuously after the peak in 1994, the mean \( {\text{SO}}_{4}^{2 - } \) output significantly exceeded the input; the 5-year means from 2010 to 2014 are 2.5 kmolc ha−1 year−1 and 0.86 kmolc ha−1 year−1, respectively. The mean δ34S values of \( {\text{SO}}_{4}^{2 - } \) in rainwater and soil solution at 20 cm depth were 4.3 ‰ and 3.5 ‰, respectively, and that in the RW was −13.2‰. The contributions of groundwater S to the RW S were estimated to range from 75 to 91%. Geological S with significantly low δ34S values largely contributed to the discrepancy of the input–output budget, while atmospheric S appeared to accumulate in soil as organic S. The tree-ring δ34S profile recorded historical changes in the atmospheric inputs in the region. With recovery of the RW, the relative contribution of atmospheric S became smaller. However, most of the atmospheric S is still retained in soil. Over the last few decades, RW chemistry has sensitively responded to changes in the atmospheric environment, including the atmospheric deposition of S and N and climatic anomalies, and as future changes are likely, long-term monitoring is essential.

Geochemistry and Mineralogy of Rare Earth Elements (REE) in Bauxitic Ores of the Catalan Coastal Range, NE Spain

Karst bauxite deposits are currently investigated as a new resource for rare earth elements (REE) in order to avoid present and future supply shortfalls of these critical metals. The present work focuses on the geochemistry and mineralogy of the REE in karst bauxite deposits of the Catalan Coastal Range (CCR), NE-Spain. It is revealed that the studied bauxitic ores have a dominant breccia and local ooido-pisoidic and pelitomorphic texture. The bauxitic ores are mostly composed of kaolinite and hematite, as well as of lesser amounts of boehmite, diaspore, rutile and calcite. The mineralogy and major element composition indicate incomplete bauxitization of an argillaceous precursor material possibly derived from the erosion of the Mesozoic Ebro massif paleo-high. The studied bauxites are characterized by ∑REE (including Sc, Y) between 286 and 820 ppm (av. 483 ppm) and light REE to heavy REE (LREE/HREE) ratios up to 10.6. REE are mainly concentrated in phosphate minerals, identified as monazite-(Ce) and xenotime-(Y) of detrital origin and unidentified REE-phosphates of a possible authigenic origin. REE remobilization presumably took place under acidic conditions, whereas REE entrapment in the form of precipitation of authigenic rare earth minerals from percolating solutions was related to neutral to slightly alkaline conditions. During the bauxitization process no significant REE fractionation took place and the REE distribution pattern of the bauxitic ores was governed by the REE budget of the precursor material. Finally, adsorption as a main REE scavenging mechanism in the studied CCR bauxite deposits should not be considered, since the presented data did not reveal significant REE contents in Fe-and Mn-oxyhydroxides and clay minerals.

A fast and quasi non-invasive muon beam monitor working at the intensity frontier

A new and high-performance generation of detectors based on scintillating fibres coupled to silicon photomultiplier (SiPM, MPPC) is under development. We focus here on the use of this technology as a beam monitoring detector with the following characteristics: high granularity, high detection efficiency, fast timing response, accurate position resolutions, minimal material budget and insensitivity to magnetic fields. We present a scintillating fibre and silicon photomultiplier-based beam monitoring detector used in one of the most intense muon beam in the world (few × 1 0 8 μ + ∕ s ). A full detector prototype was built and successfully tested at the π E5 beam line of the Paul Scherrer Institute (PSI). Beam profile and rate measurements were made with a precision of better than 1% and together with particle identification capability, are consistent with standard techniques confirming the viability of this technology for high-rate applications.

The PANDA barrel-TOF detector at FAIR

The barrel-Time-of-Flight detector is one of the outer layers of the multi-layer design of the PANDA target spectrometer. PANDA, which is being built at the FAIR facility, will use cooled antiprotons on a fixed Hydrogen or nuclei target, to study broad topics in hadron physics. The detector is designed to achieve a time resolution below 100 ps and provides the interaction times of events as well as the particle ID. The B-TOF is designed with a minimal material budget in mind mainly consisting of 5 mm thin plastic scintillator tiles read out by a serial connection of 4 SiPMs. The signal transmission is embedded in large 16 layer PCB in micro strip lines. We will first review the detector concept which is described in the TDR then some more recent developments, with a study of different PCB layouts for signal transmission, the readout with the TOFPET2 ASIC and its performance and presenting the results of a study on the influence of the scintillator thickness on the time resolution.

Radiation tolerance characterization of Geiger-mode CMOS avalanche diodes for a dual-layer particle detector

An array of Single Photon Avalanche Diodes (SPAD), fabricated in a 180 nm CMOS technology featuring a high voltage (HV) option, has been investigated in terms of radiation tolerance, in view of the design of low material budget dual-tier detectors for charged particle tracking based on the coincidence of signals coming from pairs of vertically aligned pixels. Each pixel in the array includes both the processing electronics and the sensing element in a monolithic structure. The test vehicles were irradiated with 10 keV X-rays up to a dose of 1 Mrad (SiO 2 ) and with neutrons up to a fluence of 10 11 n e q cm −2 . A selection of the characterization results are presented together with the main features of a new large scale SPAD array to be fabricated in a 150 nm CMOS technology and ready for vertical interconnection in a dual layer structure. • Characterization of SPADs in a 180 nm CMOS technology. • Radiation tolerance evaluation involving ionizing and non-ionizing sources. • Design features of a new charged particle detector based on 150 nm CMOS SPADs in a dual-layer structure.

The silicon tracking system of the CBM experiment at FAIR

The “Compressed Baryonic Matter” Experiment (CBM) is one of the four future large experiments at the Facility for Antiproton and Ion Research in Europe (FAIR) in Darmstadt. The unique feature of CBM will be an unprecedented rate capability for heavy-ion collisions (10 MHz interaction rate) at beam energies which produce maximal baryonic densities. The detector system for momentum determination is a complex, multilayer Silicon Tracking System (STS). The key challenges of this detector system are the requirement to keep the material budget to a minimum and to be able to operate in a high radiation field.

INFN-FBK developments of 3D sensors for High-Luminosity LHC

3D type of pixel sensors is a promising option for the innermost pixel layer at the High-Luminosity LHC. However, the required very high hit-rate capabilities, finer pixel granularity, extreme radiation hardness and reduced material budget call for a downscale of the pixel size as compared to existing 3D sensors, involving smaller pitch (e.g. 50 × 50 or 25×100μm2), shorter inter-electrode spacing (∼30μm), narrower electrodes (∼6μm diameter), and reduced active thickness (∼100–150μm). Within a joint R&D effort with INFN, FBK has produced a new generation of 3D pixel sensors with these challenging features. In this talk preliminary results from the electrical and functional characterisation of the first prototypes are reported, included their behaviour after large radiation fluence, close to the ones expected in the High Luminosity LHC environment. Prospects for the next prototypes are also presented.

The tracking system for the IDEA detector at future lepton colliders

While most requirements for detectors at the International Linear Collider (ILC) are very similar to those for the future circular e + e − -colliders FCC–ee ( e + e − Future Circular Collider at CERN) or CEPC (Circular Electron–Positron Collider at IHEP, China), the luminosity is expected to be one or two orders of magnitude larger, with a much shorter bunch spacing, placing severe constraints on the tracking system, favouring an intrinsically fast main tracker to fully exploit the cleanliness of the e + e − environment. Moreover, limits on the maximum magnetic field of the tracker solenoid represent a problem for a large volume TPC, because of the resolution degradation, and for a Si tracker, since it would require a larger radius. The proposed ultra-light He based Drift Chamber is 4 m long, starting at a radius of ∼ 30 c m and extending up to 2 m , with ≲ 1 . 5 c m drift cells, arranged in a fully stereo configuration ( ( 50 – 250 ) m r a d ) and instrumented with readout electronics implementing the Cluster Counting/Timing technique. The total material budget is approximately 0 . 016 X 0 for tracks in the barrel region and 0 . 05 X 0 for forward tracks, providing a momentum resolution of ∼ 5 × 1 0 − 4 for < 10 G e V ∕ c and of < 4 × 1 0 − 3 for 100 G e V ∕ c tracks. Moreover, the use of the Cluster Counting technique will allow for a particle identification (PID) resolution < 3 % , a factor two better than the resolution attainable with dE/dx technique. We will illustrate the tracking system performance obtained with detailed simulations. The hardware features and the construction procedures of the proposed Drift Chamber, making use of the assembly technique developed for MEG2, will also be presented. • Drift chamber proposal for the next generation of electron–positron accelerators. • Ultra-light helium based, fully stereo (no axial layers) drift chamber. • High spatial resolution obtained thanks to the cluster timing technique. • High particle identification capabilities thanks to the cluster counting technique.

Outcome of the KLOE-2 experiment after the conclusion of the data-taking period

The KLOE-2 experiment at the INFN-LNF has concluded the data taking campaign at DA Φ NE collider with more than 5 fb −1 of integrated luminosity collected. The KLOE detector received several upgrades to improve the performance and enlarge the physics reach: two new low angle calorimeters , a lepton tagging system for γ γ physics, and near the interaction point a state-of-the-art cylindrical triple-GEM detector has been installed as Inner Tracker. Performances of the detectors, preliminary results obtained including the Inner Tracker in the reconstruction and data quality monitoring are here discussed. • KLOE-2 first HEP experiment that build/operated ultra-light/compact tracking systems. • The biggest transparent Drift Chamber in 5.2 kGauss field of a superconductor coil. • Carbon fiber walls, 55000 stereo wires, 2 m radius, 4 m long, He/iC 4 H 10 gas mixture. • First multi-layer cylindrical triple-GEM detector for fine vertex reconstruction. • Total material budget below 2% of the radiation length X 0 .

Development of an ultra thin beam profiler for charged particle beams

Abstract Beam profiling during patient treatment in protontherapy requires ultra-thin monitors to preserve the high beam quality. For detectors upstream in the line, a material budget as low as ∼ 15 μ m water-equivalent is needed. In addition, the current trend of dose escalation to treat highly resistant tumors implies challenging requirements on monitor radiation hardness and dynamic range. We propose a new type of beam profiler, PEPITES, using secondary electron emission (SEE) and built with thin-film techniques. The beam is profiled by crossing a pattern or a series of patterns which emit the SEE signal and can be made ultra-thin as SEE originates from the few nanometers next to the surface. The patterns are deposited on membranes, which, in contrast with common systems like ionization chambers , are free from mechanical constraints and can then afford higher absorbed doses and be as thin as achievable. A simple demonstrator prototype has been built and successfully operated with a proton beam at the ARRONAX cyclotron at St Herblain in a wide range of currents (100 fA to 10 nA) and several energies (30 - 68 MeV). Beam profiling results from these tests are presented, and our plans for the next prototypes are mentioned.

The Gigatracker detector of the NA62 experiment at CERN SPS

Abstract The NA62 experiment at the CERN SPS is a fixed target experiment designed to measure the branching ratio of the ultra-rare Kaon decay K + → π + ν ν . The experiment uses an high-momentum K + decay in-flight technique to increase the rejection power of the main background: K + → π + π 0 . The Gigatracker is a hybrid silicon pixel detector, exposed to a 750 MHz high-energy charged hadron beam, built to give an accurate measurement of K + momentum and direction together with an high precision measurement of the beam particle arrival time (115 ps RMS resolution per plane). It comprises three stations placed right before the K + decay region and inserted around two achromats. The detector works in vacuum ( ∼ 1 0 − 6 mbar ) at about − 10 ° C . Each station is made of a 200 μ m thick silicon sensor readout by 10 TDCPix, custom 100 μ m thick ASICs, and cooled by an innovative double circuit silicon micro-channel cooling system. All these parts are designed to minimize the total material budget which, in the final detector, amounts to less than 1.5% X 0 for the three stations. In order to sustain the high rate of incoming particles, each TDCPix, operating in a self triggered mode, is equipped with four 3.2 Gb/s serializers sending data to the detector DAQ system based on a read-out card per TDCPix chip sending trigger-matched hits to 6 PC servers. I will describe the whole detector and present some of the results from data collected during the 2016 NA62 runs.

Study of vertex optimization at the CEPC

The CEPC is a planned future collider targeting precise Higgs property measurements. Its core physics program includes the determination of Br(H→ bb), Br(H→ cc), and Br(H→ τ+τ−), whose accuracies are sensitive to the vertex (VTX) design and the performance. This study is performed on Higgsstrahlung events e+e−→ ZH at √s = 240 GeV, with subsequent Higgs decay to bb, cc and ττ. Using full simulation, we quantified the dependency between these physics performances and the main VTX geometry parameters: the inner radius, the material budget, and the spatial resolution. We select three benchmark VTX designs, a conservative design according to the upgraded ALICE Inner Tracker System (ITS) geometry, a baseline detector design that is roughly two times better than the upgraded ALICE ITS, and an aggressive design that is roughly four times better. Comparing the physics performance at the aggressive design to the baseline one, we found the Br(H→ cc) measurement is extremely sensitive and the relative accuracy could change up to 40%. The relative accuracy on Br(H→ τ+τ−) changes by 8%. The Br(H→ bb) is not really sensitive to the VTX parameters and the relative accuracy only changes by 1%. Our analyses also show that the reduction of the inner radius is the most efficient way to improve the performance on Br(H→ cc) measurements.

Technologies for future vertex and tracking detectors at CLIC

CLIC is a proposed linear $e^{+}e^{-}$ collider with center-of-mass energies of up to $3\,\textrm{TeV}$. Its main objectives are precise top quark and Higgs boson measurements, as well as searches for Beyond Standard Model physics. To meet the physics goals, the vertex and tracking detectors require not only a spatial resolution of a few micrometers and a very low material budget, but also timing capabilities with a precision of a few nanoseconds to allow suppression of beam-induced backgrounds. Different technologies using hybrid silicon detectors are explored for the vertex detectors, such as dedicated readout ASICs, small-pitch active edge sensors as well as capacitively coupled High-Voltage CMOS sensors. Monolithic sensors are considered as an option for the tracking detector, and a prototype using a CMOS process with a high-resistivity epitaxial layer is being designed. Different designs using a silicon-on-insulator process are under investigation for both vertex and tracking detector. All prototypes are evaluated in laboratory and beam tests, and newly developed simulation tools combining Geant4 and TCAD are used to assess and optimize their performance. This contribution gives an overview of the R&D program for the CLIC vertex and tracking detectors, highlighting new results from the prototypes.

IMPACT: An Innovative Tracker and Calorimeter for Proton Computed Tomography

This contribution describes the first results obtained within the iMPACT project, which aims to build a novel proton computed-tomography (pCT) scanner for protons of energy up to 230 MeV, as used in hadron therapy. The iMPACT pCT scanner will improve the current state-of-the-art in proton tracking at all levels: speed, spatial resolution, material budget, and cost. We will first describe the design of the iMPACT scanner, which is composed by a tracker and a range calorimeter. We will then illustrate the results of a test with the ALPIDE sensor, a monolithic active pixels sensor, developed by the ALICE collaboration, which will equip the iMPACT tracker in this first phase. We finally detail the characterization building elements of the prototype of the range calorimeter, which is composed of segmented scintillator fingers readout by SiPMs. Reported beam-test data will highlight how the technological choices we made well address the performances of a state-of-the-art pCT system.

Monolithic CMOS sensors for high energy physics

Monolithic active pixel sensors manufactured in commercial CMOS technologies revolutionized imaging for consumer applications and are now moving into high energy physics: they have been adopted in the STAR and the ALICE experiments, and are being considered for the most demanding applications like the upgrade of the ATLAS pixel detector. These devices offer integration of sensor and readout in a single chip and low material budget. Deep submicron commercial CMOS technologies offer high speed and density, leading to high bandwidth capability and good spatial resolution for monolithic sensors, and volume production capability at low cost, important for large systems. This paper tries to give an overview.

Characterization of a depleted monolithic pixel sensors in 150 nm CMOS technology for the ATLAS Inner Tracker upgrade

This work presents a depleted monolithic active pixel sensor (DMAPS) prototype manufactured in the LFoundry 150\,nm CMOS process. DMAPS exploit high voltage and/or high resistivity inclusion of modern CMOS technologies to achieve substantial depletion in the sensing volume. The described device, named LF-Monopix, was designed as a proof of concept of a fully monolithic sensor capable of operating in the environment of outer layers of the ATLAS Inner Tracker upgrade in 2025 for the High Luminosity Large Hadron Collider (HL-LHC). This type of devices has a lower production cost and lower material budget compared to presently used hybrid designs. In this work, the chip architecture will be described followed by the characterization of the different pre-amplifier and discriminator flavors with an external injection signal and an iron source (5.9\,keV x-rays).

Pressure stabilized straw tube modules for the PANDA Forward Tracker

The design of straw tube detector modules developed for the PANDA Forward Tracker is presented. One module consists of 32 straws with 10 mm diameter, arranged in two staggered layers, and has a very low material budget of only 8.8⋅10−4X0. The overpressure of the working gas mixture of 1 bar makes the module self-supporting and enables the use of lightweight and compact support frames. Detection planes in the Forward Tracker consist of modules mounted closely, without gaps, next to each other on a support frame. A module can be mounted and dismounted from the frame without the need to remove the neighboring modules, enabling fast repairs. Technical details of the detector design and the assembly procedure of the straw tubes and the straw modules as well as results of performed tests of the modules are given.

Using a Workflow to Reduce Database Costs without Affecting Collection Needs

A small university with limited staff and resources created a workflow to help streamline decision making during renewal of subject databases. A literature review of common assessment methods found cost per use, content overlap analysis, and relevance to the curriculum to be the most common metrics. However, each individually provided an incomplete portrait of usage. A flowchart documented the decision process and incorporated multiple metrics. Implementing this workflow reduced the library’s materials budget by 3% for the following fiscal year. This process may be implemented at other libraries to lower overall budget spending, while still providing content aligned with the local curriculum.

Feasibility of track-based multiple scattering tomography

We present a tomographic technique making use of a gigaelectronvolt electron beam for the determination of the material budget distribution of centimeter-sized objects by means of simulations and measurements. In both cases, the trajectory of electrons traversing a sample under test is reconstructed using a pixel beam-telescope. The width of the deflection angle distribution of electrons undergoing multiple Coulomb scattering at the sample is estimated. Basing the sinogram on position-resolved estimators enables the reconstruction of the original sample using an inverse radon transform. We exemplify the feasibility of this tomographic technique via simulations of two structured cubes—made of aluminium and lead—and via an in-beam measured coaxial adapter. The simulations yield images with FWHM edge resolutions of (177 ± 13) μm and a contrast-to-noise ratio of 5.6 ± 0.2 (7.8 ± 0.3) for aluminium (lead) compared to air. The tomographic reconstruction of a coaxial adapter serves as experimental evidence of the technique and yields a contrast-to-noise ratio of 15.3 ± 1.0 and a FWHM edge resolution of (117 ± 4) μm.