Strip Detectors Research Articles

DECAL: A Reconfigurable Monolithic Active Pixel Sensor for Tracking and Calorimetry in a 180 nm Image Sensor Process.

In this paper, we describe DECAL, a prototype Monolithic Active Pixel Sensor (MAPS) device designed to demonstrate the feasibility of both digital calorimetry and reconfigurability in ASICs for particle physics. The goal of this architecture is to help reduce the development and manufacturing costs of detectors for future colliders by developing a chip that can operate both as a digital silicon calorimeter and a tracking chip. The prototype sensor consists of a matrix of 64 × 64 55 m pixels, and provides a readout at 40 MHz of the number of particles which have struck the matrix in the preceding 25 ns. It can be configured to report this as a total sum across the sensor (equivalent to the pad of an analogue calorimeter) or the sum per column (equivalent to a traditional strip detector). The design and operation of the sensor are described, and the results of chip characterisation are reported and compared to simulations.

Investigation of mixed irradiation effects in p-MCz thin silicon microstrip detector for the HL-LHC experiments

A lot of R&D work is carried out in the CERN RD 50 collaboration to find out the best material for the Si detectors that can be used in the harsh radiation environment of HL-LHC, n and p-MCz Si was identified as one of the prime candidates as a material for strip detector that can be chosen for the phase 2 upgrade plan of the new Compact Muon Solenoid Tracker detector in 2026. In this work, four level deep-trap mixed irradiation model for p-MCz Si is proposed by the comparison of experimental data on the full depletion voltage and leakage current to the Shockley Read Hall recombination statistics results on the mixed irradiated p-MCz Si PAD detector. The effective introduction rate (η eff) of shallower donor deep trap E30K is extracted using SRH theory calculations for experimental N eff and that can show the behavior of space charges and electric field distribution in the p-MCz Si strip detector and compared its value with the η eff of shallower donor deep trap E30K in the nMCz Si microstrip detector. Prediction uncertainty in the p-MCz Si radiation damage mixed irradiation model is considered in the full depletion voltage and leakage current. A very good agreement is observed in the experimental and SRH results. This radiation damage model is also used to extrapolate the value of the full depletion voltage at different mixed (proton + neutron) higher irradiation fluences for the thin p-MCz Si microstrip detector.

32-Channel silicon strip detection module for combined X-ray fluorescence spectroscopy and X-ray diffractometry analysis

A compact detection module for the simultaneous measurement of XRF and XRD in portable analytical applications, in particular in the mining sector, is presented. The detector head is based on 32 silicon strip detectors, fabricated with a low-leakage technology by FBK and readout by two 16-channel low-noise CUBE charge-sensitive amplifiers. The design of the module and its characterization are reported. Multiple configurations are experimentally compared in terms of strip length, spacing, collimation and charge sharing effects. The optimal configuration for a strip length of 6 mm and pitch 0.2 mm is thus identified. It offers an energy resolution of better than 200 eV at 5.9 keV with moderate cooling (−10°C) and peaking time of 14 μs.

Operation and readout of the CGEM inner tracker

A recently approved ten-year extension of the BESIII experiment (IHEP, Beijing) motivated an upgrade program for both the accelerator and the detector. In particular, the current inner drift chamber is suffering from aging and the proposal is to replace it with a detector based on the cylindrical GEM technology. The CGEM inner tracker (CGEM-IT) consists of three coaxial layers of triple-GEM. The tracker is expected to restore efficiency, improve z-determination and secondary vertex position reconstruction with a spatial resolution of 130μm in the xy-plane and better than 300μm along the beam direction. A dedicated readout system was developed. Signals from the detector strips are processed by TIGER, a custom-made 64-channel ASIC that provides an analog charge readout via a fully digital output up to about 50fC and less than 3ns jitter. TIGER continuously streams over-threshold data in trigger-less mode to an FPGA-based readout module, called GEM Read Out Card, that organizes the incoming data by building the event packets when the trigger arrives. Two of the three layers are in operation in Beijing since December 2019 and remotely controlled since January 2020. Due to the pandemic situation the integration activity has been continued on a small-scale prototype. Recently, a test beam has been performed at CERN with the final electronics configuration. In this presentation, the general status of the CGEM-IT project will be presented with a particular focus on the results from the test beam data acquisition.

New beam position detectors for NA61/SHINE experiment

NA61/SHINE is a multi-purpose fixed-target experiment located at the Super Proton Synchrotron at CERN. The main goals of the experiment include studies for physics of strong interactions, neutrino physics, and cosmic-rays physics. After the upgrade of the detector system, the experiment will collect data up to 1 kHz event rate. The development of new detectors, used to measure the positions of incoming beam particles in the transverse plane, is a crucial part of the upgrade. Two new kinds of beam position detectors are prepared and tested. One of them is the scintillating fiber detector with a multi-anode photomultiplier readout. It is built of two perpendicularly arranged ribbons, each consisting of two shifted layers of green-emitting scintillating fibers with a diameter of 250 μm. The second type of detector is based on single-sided silicon strip detector (Hamamatsu S13804). The paper gives an overview of both detectors’ design and readout concepts.

Strip detector array (SDA) for beam monitoring in radiotherapy: reconstruction of MLC parameters from multiple projections of flux

Objective. In this paper we propose and investigate a new detector with multiple strip detector arrays (SDA) for monitoring MLC shaped x-ray beams for radiotherapy treatment. Approach. Each SDA measures 1D dose profiles equivalent to dose projections. The goal of such a detector is to determine individual MLC leaf positions as well as the Monitor Units (MU) per MLC segment during radiotherapy. In the present work we investigate an optimal SDA detector configuration and reconstruction algorithm. We determine the accuracy of SDA for different treatment sites (spine, pelvis, retroperitoneum, prostate, brain SRT, SRS, lung and head and neck). We perform a simulation study accounting for different type of MLC leaf positional errors: random MLC leaf, systematic for the whole leaf bank and systematic for an individual leaf. In a similar fashion, we also account for errors in Monitor Units per segment. Main results. We demonstrate that for a broad range of IMRT treatment plans a robust reconstruction of errors is achievable with only 3 projections (3 sets of SDA oriented at at 0°, 45° and 135°). The SDA is capable of capturing both systematic errors in leaf banks and individual leaves as well as random errors sufficient for practical clinical purposes. Significance. These features of the SDA detector makes it suitable for real-time Quality Control of MLC collimated linac output.

Measurements of proton beam attenuation radiographs at a clinical facility

In recent years, a proton computed tomography (pCT) demonstrator was installed and tested at the MedAustron facility in Wiener Neustadt, Austria. It consists of four double-sided silicon strip detectors (DSSDs) for particle tracking and a range telescope to obtain the residual range of the protons that passed through the object to be imaged. Besides conventional pCT, which uses the energy loss information of the single ions, the tracker of the demonstrator also allows for other imaging modalities such as beam attenuation imaging (also referred to as fluence loss imaging). When a proton beam passes through a medium, a certain fraction of the incident primary particles gets absorbed due to the inelastic scattering with the atomic nuclei of the material. Recent studies investigating proton imaging based on inelastic nuclear scattering at clinical energies with single-particle tracking used Monte Carlo simulations and lack additional experimental validation. In this work, proton radiographs based on beam attenuation were measured at clinical beam energies (100.4 MeV, 145.4 MeV) and, for the first time, at 800 MeV. As phantom, an aluminum stair profile was imaged at two different rotation angles to investigate material thicknesses between 2 mm and 10 mm. The recorded beam attenuation was compared to existing reference data from prior measurements and the inelastic nuclear cross sections as incorporated in the Geant4 database. Furthermore, the measurement at 800MeV could be compared to an existing measurement of the inelastic nuclear cross section of aluminum at a similar energy (792.9 MeV).

Performance study of dual-phase CO[formula omitted] cooling on the example of the ATLAS ITk strip end-cap detector

The technique of evaporative CO2 cooling is one of the standard cooling options for high-energy particle detectors, such as the new ATLAS Inner Tracker (ITk) for the planned high-luminosity upgrade of the LHC by 2026. The advantages of CO2 are a high latent heat transfer at reasonable flow parameters, a low viscosity which allows to use small diameter cooling pipes with a low pressure drops, a well-suited temperature range for detector cooling between ＋25 and −40 °C and being an environment friendly alternative to many other currently used coolants. When comparing with a monophase coolant, the operation in the dual-phase regime comes with several parameters influencing the cooling performance.This paper contains the results of experimental studies performed to understand these influencing factors. For this, prototype structures from the ITk strip detector end-cap were used, like bare local support structures (‘cores’) or fully loaded structures (‘petals’). Here, the design is optimized to guarantee a good heat transfer between the silicon strip modules glued on the surface and the embedded titanium cooling pipe with the CO2 coolant. Systematic investigations on the thermal performance using infrared thermography are used to study the influence of dual-phase CO2 cooling parameters such as the orientation of CO2 flow. Moreover, the dependence of the pressure drop as a key parameter for the cooling performance on the applied heat load or the selected mass flow rate is investigated.

Absolute mass calibration of fission product distributions measured with the E-[formula omitted] method

The mass calibration of fission product distributions measured with the energy–velocity (E-υ) method constitutes a technical challenge. The energy loss of the fission fragments in the various dead layers of the spectrometer and other sources of pulse-height defects of the energy detectors are a significant source of systematic uncertainty in the mass calculations used to determine the measured fission product yields. In this study, the absolute calibration of the fission mass distributions is accomplished by measuring prompt γ-rays in coincidence with the fission fragments. This allows for the direct calibration of the mass spectra and eliminates any dependence on potentially complicated energy corrections. The first test measurement was performed at the Los Alamos Neutron Science Center employing the SPectrometer for Ion DEtermination in fission Research (SPIDER). SPIDER is a 2E-2υ spectrometer designed for measuring independent fission product yields from neutron-induced fission. In this test, the single-arm SPIDER (E-υ) system and an array of 252Cf sources were used. The single-arm system consisted of two time pick-off detectors for measuring the time-of-flight of the fission fragments and a double-sided silicon strip detector (DSSD) for measuring the kinetic energy. Characteristic γ-rays from fission fragments were detected using three high-purity germanium (HPGe) detectors. For the mass calibration, γ–mass coincidence events from twelve product isotopes were used. The measured FPYs from 252Cf spontaneous fission were found to be in excellent agreement with the evaluated data after applying the absolute mass calibration. From the γ–mass coincidence events, the mass resolution of the system was also extracted. An average mass resolution of ∼1.4 AMU (FWHM) for the light fragments and ∼2.4 AMU (FWHM) for the heavy fragments were found. This was the first in-situ calibration and characterization of the SPIDER spectrometer, which paves the way for high-quality FPY measurements with this instrument.

Position dispersive X-ray fluorescence

A novel scanning-free wavelength dispersive X-ray fluorescence spectrometer has been developed by combining low power X-ray tubes with X-ray optics. The X-rays are focused to a single point on the sample and then dispersed onto a flat diffracting crystal where they are spread depending on their energy through Bragg's law of diffraction onto a silicon strip detector. Throughout this study, the proposed method is referred to as Position Dispersive X-ray Fluorescence (PDXRF). The X-ray emission spectra of vanadium and copper as well as, CuO, CuS2 and V2O5 were measured. In the spectrometer energy resolutions of 3.14 eV and 8.94 eV FWHM were measured for V and Cu when measuring over a range of 4.8–5.8 keV and 6.2–9.1 keV respectively. The Kβ line shapes were fitted with a series of Voigt profiles and the energies and intensities of the Kβ valence transition peak, Kβ2,5, were determined. There was also sufficient variation in the intensity ratio of Kβ2,5/Kβ1,3 that the oxygen and sulphur compounds of V and Cu could be successfully observed and measured. The result demonstrates that this experimental setup is capable of measuring the Kβ line shape at resolutions of a few eV, allowing for chemical state analysis to be performed on 3d transition metals and their compounds such as the measurement of redox reactions to aid in battery development.

Non-destructive 3D imaging method using muonic X-rays and a CdTe double-sided strip detector

Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft gamma-ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.

Flexible algorithms for background suppression in heavy ion induced nuclear reactions

A new algorithm for the analog spectrometer of the DGFRS-2 setup installed at DC-280 cyclotron is presented. The main goal of application of this algorithm is to search an optimal time correlation recoilalpha parameter directly during the acquisition C++ code execution. A new real-time flexible algorithm in addition to the conventional ER − a algorithm, which has been used for a several years at the DGFRS-1 setup installed at the U-400 FLNR cyclotron, is presented. The main parts of the spectrometer are a 48×128 strip DSSD detector (Double Side Strip Detector) and a low-pressure gaseous detector. They are presented schematically. Nuclear reactions for synthesis of element Z=119 at the DGFRS-2 are under consideration. Some attention is paid to computer simulation of the heavy recoil spectra, taking into account its pulse height defect in silicon. First beam test results are also presented. A new formula for half-life time using recent data for superheavy nuclei is obtained.

Design of the Front-End Electronics for Silicon Beam Profilometer Prototype for Light Ions at the BM@N Experiment

Baryonic matter at nuclotron (BM@N) is the fixed-target experiment at the Nuclotron based Ion Collider fAcility (NICA) complex [the Joint Institute for Nuclear Research (JINR), Dubna]. Two beam profilometer planes will be placed inside the beam pipe and used for a beam tuning during the initial stage in the BM@N experiment. According to the physics program of the experiment, beam ions are foreseen from carbon to gold. Due to the wide input charge range, two versions of front-end electronics (FEEs) for the beam profilometer will be used—for light and heavy ions. The article presents the first stage of a beam profilometer development—the design of a prototype for light ions based on a double-sided silicon strip detector and FEE application-specific integrated circuits (ASICs).

Automated visual inspection and defect detection of large-scale silicon strip sensors

For the Phase-II Upgrade of the ATLAS Detector, the Inner Detector will be replaced with the Inner Tracker (ITk), consisting of a pixel and a strip tracker. The 17,888 silicon strip detector modules comprising the ITk strip tracker will be assembled from silicon strip sensors and flexes with readout chips in a manual assembly process performed at 20 module assembly sites in a complex distribution chain, which requires quality control steps to be performed after each distribution and assembly step. Sensor quality control requires a visual inspection of the full sensor area (about 100 cm2) of each sensor to detect and log any defects (e.g. scratches, breakdown areas or chipped corners) or contamination. Since manual surveys of full sensor areas for several thousand sensors are both time-consuming and prone to errors, alternative methods were investigated to automate the process and improve its reliability. This paper presents a setup developed to take high-resolution images of full silicon strip sensors with high repeatability quickly and an algorithm developed for the automated detection of defects, built using functions and filters from popular open-source visual processing packages OpenCV and Scikit-image. Methods were developed both for small-scale high-resolution images and full-size sensor images with lower resolution — both are presented here.

Potentialities of High-Resolution 3-D CZT Drift Strip Detectors for Prompt Gamma-Ray Measurements in BNCT.

Recently, new high-resolution cadmium–zinc–telluride (CZT) drift strip detectors for room temperature gamma-ray spectroscopic imaging were developed by our group. The CZT detectors equipped with orthogonal anode/cathode collecting strips, drift strips and dedicated pulse processing allow a detection area of 6 × 20 mm2 and excellent room temperature spectroscopic performance (0.82% FWHM at 661.7 keV). In this work, we investigated the potentialities of these detectors for prompt gamma-ray spectroscopy (PGS) in boron neutron capture therapy (BNCT). The detectors, exploiting the measurement of the 478 keV prompt gamma rays emitted by 94% 7Li nuclides from the 10B(n, α)7Li reaction, are very appealing for the development of single-photon emission computed tomography (SPECT) systems and Compton cameras in BNCT. High-resolution gamma-ray spectra from 10B samples under thermal neutrons were measured at the T.R.I.G.A. Mark II research nuclear reactor of the University of Pavia (Italy).

Track recognition for the [formula omitted] telescopes with silicon strip detectors

For the high granularity and high energy resolution, Silicon Strip Detector (SSD) is widely applied in assembling telescopes to measure the charged particles in heavy ion reactions. In this paper, we present a novel method to achieve track recognition in the SSD telescopes of the Compact Spectrometer for Heavy Ion Experiment (CSHINE). Each telescope consists of a single-sided silicon strip detector (SSSSD) and a double-sided silicon strip detector (DSSSD) backed by 3 × 3 CsI(Tl) crystals. Detector calibration and track reconstruction are implemented. Special decoding algorithm is developed for the multi-track recognition procedure to deal with the multi-hit effect convoluted by charge sharing and the missing signals with certain probability. It is demonstrated that the track recognition efficiency of the method is approximately 90% and 80% for the DSSSD-CsI and SSSSD–DSSSD events, respectively.

The SFiNx Detector System

A new detector system for investigating the properties of spontaneous fission of short-lived transuranium nuclei has been created. This system consists of an assembly of double-sided silicon strip detectors surrounded by 116 proportional neutrons counters filled with 3He. The neutron registration efficiency is 54.7 ± 0.1%. The detector system is tested in an experiment investigating the characteristics of spontaneous fission of the 252No isotope. The experimental data on neutron yields are compared with previously published results. The average number of neutrons per fission act ( $$\bar {\nu }$$ = 4.25 $$ \pm $$ 0.09) and the multiplicity distribution of prompt neutrons are obtained. The true form of the neutron distribution is reconstructed via a statistical regularization.

Stopping power measurement for proton therapy by combining proton radiography and X-ray CT

Exact information on the relative stopping power (RSP) of the high-energy proton in the human body is necessary to precisely control radiation dose and position in proton beam therapy. RSP has been estimated by converting the X-ray computed tomography (CT) information. However, it causes up to 5% uncertainty in the RSP measurements because of the fundamental difference between the X-ray and proton interaction. Therefore, this study investigates a scheme of the RSP distribution measurement in the human body with a combination of X-ray CT and proton radiography with beam injection to a single direction. We studied the accuracy of the RSP measurement using GEANT4 simulation with silicon trackers, crystal calorimeter, and proton beam. The RSP accuracy has been generally measured below 1% from the reference values for simple objects with multi cylindrical shapes. The simulation results present the requirements of a proton tracking system on the spatial resolution and the acquisition rate. We developed a tracking detector prototype consisting of double-sided silicon strip detectors and amplifier–shaper–discriminator LSI chips. We evaluated the performance with an 80 MeV proton beam in Cyclotron and Radioisotope Center, Tohoku University. It succeeded in reconstructing a proton trajectory with 160 kHz and fulfilled the requirements to realize the proposed scheme. Furthermore, this study describes the detailed study of the scheme of the RSP measurement and the beam test of the tracking system prototype.

Evaluation of silicon strip detectors in transmission mode for online beam monitoring in microbeam radiation therapy at the Australian Synchrotron.

Successful transition of synchrotron-based microbeam radiation therapy (MRT) from pre-clinical animal studies to human trials is dependent upon ensuring that there are sufficient and adequate measures in place for quality assurance purposes. Transmission detectors provide researchers and clinicians with a real-time quality assurance and beam-monitoring instrument to ensure safe and accurate dose delivery. In this work, the effect of transmission detectors of different thicknesses (10 and 375 µm) upon the photon energy spectra and dose deposition of spatially fractionated synchrotron radiation is quantified experimentally and by means of a dedicated Geant4 simulation study. The simulation and experimental results confirm that the presence of the 375 µm thick transmission detector results in an approximately 1-6% decrease in broad-beam and microbeam peak dose. The capability to account for the reduction in dose and change to the peak-to-valley dose ratio justifies the use of transmission detectors as thick as 375 µm in MRT provided that treatment planning systems are able to account for their presence. The simulation and experimental results confirm that the presence of the 10 µm thick transmission detector shows a negligible impact (<0.5%) on the photon energy spectra, dose delivery and microbeam structure for both broad-beam and microbeam cases. Whilst the use of 375 µm thick detectors would certainly be appropriate, based upon the idea of best practice the authors recommend that 10 µm thick transmission detectors of this sort be utilized as a real-time quality assurance and beam-monitoring tool during MRT.

The Test Bench for BM@N Forward Silicon Tracker Front-End Electronics and Silicon Modules

The forward silicon tracker (FST) is an integral part of the central tracker located in the analyzing magnet of the Baryonic Matter at Nuclotron (BM@N) experiment setup to improve the efficiency and accuracy of the particle tracks and primary vertex reconstructions. The FST consists of three planes based on 42 double-sided silicon strip detector modules. To meet the experiment requirements, each front-end electronics (FEE) printed circuit board (PCB) and the silicon module should be effectively tested before installation to the FST subsystem. This task was solved by designing and producing a test bench. The test bench consists of special testing boxes for FEE PCBs, silicon modules, power supply, slow controls, and data acquisition subsystems. The data acquisition subsystem uses an field-programmable gate array (FPGA)-based control unit, and data storage and analysis subsystems to control the data flows in the test bench during measurements. All measurements are managed, stored, and analyzed automatically. The test bench provides a user-friendly web interface inside the local network for the raw and analyzed data and individual test reports for each device. The test bench structure, testing procedures, data analysis algorithms, and test results are described in detail.