Particle Detection Efficiency Research Articles

High-Voltage Monolithic Active Pixel Sensors Based Tracker for the Mu3e Experiment

The Mu3e experiment is searching for the decay µ + → e+ e− e+ , which involves a violation of charged lepton flavor. The goal is to achieve a branching fraction sensitivity of four orders of magnitude higher than existing limits. To accurately measure the momentum and vertex position of low momentum electrons (10-53 MeV/c) produced by this rare decay, a tracking detector made from High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) has been used. The MuPix7 chip has an HV- MAPS architecture and is manufactured using 180 nm High Voltage CMOS (HV-CMOS) technology. HV-MAPS are preferred due to their ability to be thinned to 50 µm, tolerance to radiation, high time resolution, and cost-effectiveness. Additionally, to minimize the material used, the pixel readout electronics are embedded inside the sensor chip, supported by a low-mass mechanical structure built with 25 µm Kapton foil. The MuPix7 chip is the first HV-MAPS prototype that implements all functionalities of the final sensor, including a readout state machine. Based on a high-rate test beam, the it has a particle detection efficiency of 99% and meets all the requirements for a small-scale prototype.

Flexible biopolymer photodetectors based Er, Tb doped BaW[formula omitted]@CS for enhanced light-sensitive coatings

Flexible biopolymer photodetectors based Er, Tb doped BaW[formula omitted]@CS for enhanced light-sensitive coatings

Scintillation characteristics of the EJ-299-02H scintillator.

A study of the dead layer thickness and quenching factor of a plastic scintillator for use in ultracold neutron (UCN) experiments is described. Alpha spectroscopy was used to determine the thickness of a thin surface dead layer to be 630 ± 110nm. The relative light outputs from the decay of 241Am and Compton scattering of electrons were used to extract Birks' law coefficient, yielding a kB value of 0.087 ± 0.003 mm/MeV, consistent with some previous reports for other polystyrene-based scintillators. The results from these measurements are incorporated into the simulation to show that an energy threshold of (∼9keV) can be achieved for the UCNProBe experiment. This low threshold enables high beta particle detection efficiency and the indirect measurement of UCN. The ability to make the scintillator deuterated, accompanied by its relatively thin dead layer, gives rise to unique applications in a wide range of UCN experiments, where it can be used to trap UCN and detect charged particles in situ.

Development and characterization of a high-performance single-particle aerosol mass spectrometer (HP-SPAMS)

Abstract. This study describes a high-performance single-particle mass spectrometry (HP-SPAMS) design in detail. The comprehensive improvements in the injection system, optical sizing system, mass spectrometry, and data acquisition system have improved particle detection efficiency and chemical analysis. The combination of an aerodynamic particle concentrator (APC) system and a wide range of aerodynamic lenses (ADLs) enables the concentration of particles in the 100–5000 nm range. Using an APC increases the instrument inlet flow by a factor of 3–5. The ion delayed-exaction technology of bipolar time-of-flight mass spectrometry improves the mass resolution by 2–3 times, allowing the differentiation of isobaric ions of different substances. Moreover, the four-channel data acquisition technology greatly enhances the dynamic range of mass spectrometry. The improved HP-SPAMS enhances the overall capability of the instrument in terms of particle detection number and scattering efficiency. Moreover, it improves accuracy and sensitivity for component identification of individual particles. The experimental performance of HP-SPAMS shows that the scattering efficiency of polystyrene latex microspheres is almost 70 %–100 % in the range of 300–3000 nm. Compared to the previous SPAMS, HP-SPAMS has a larger inlet flow rate and scattering efficiency and a higher laser frequency, which makes HP-SPAMS increase the effective number of particles detected and improve the temporal resolution of detection. For the analysis of individual particles, HP-SPAMS achieves an average mass spectral resolution of 2500 at m/z 208, which helps distinguish between most organic fragment ions and metal ions and facilitates the analysis of complex aerosol particles. For the analysis of individual particles, the increased resolution of the HP-SPAMS contributes to the differentiation of most organic fragment ions and metal ions and facilitates the evaluation of complex aerosol particles, in the case of atmospheric lead-containing particles. The improved detection efficiency and chemical analysis capability of HP-SPAMS will be of great importance for low-concentration aerosol detection and complex aerosol component analysis.

First measurements with monolithic active pixel test structures produced in a 65 nm CMOS process

The Inner Tracking System (ITS) of the ALICE experiment at CERN will undergo an upgrade during the LHC long shutdown 3, in which the three innermost tracking layers will be replaced. This upgrade, named the Inner Tracking System 3 (ITS3), employs stitched wafer-scale Monolithic Active Pixel Sensors fabricated in a 65 nm CMOS process. The sensors are 260 mm in length and thinned to less than 50 μm then bent to form truly half-cylindrical half-barrels. The feasibility of this process for the ITS3 was explored with the first test production run (MLR1) in 2021, whose goal was to evaluate the charged particle detection efficiency and the sensor performance under non-ionising and ionising radiation up to the expected levels for ALICE ITS3 of 1013 1 MeV neq cm-2 (NIEL) and 10 kGy (TID). Three sensor flavours were produced to investigate this process: Analog Pixel Test Structure (APTS), Circuit Exploratoire 65 (CE65) and Digital Pixel Test Structure (DPTS).This contribution gives an overview of the MLR1 submission and test results, describing the different sensor flavours and presenting the results of the performance measurements done with particle beams for various chip variants and irradiation levels.

Digital coincidence counting with 4πβ(PPC)-γ for the standardization of 60Co

A 4πβ(PPC)-γ coincidence system has been made at KRISS based on a digital DAQ. 60Co sources were measured to verify the system. The maximum detection efficiency for beta particles was estimated to be 96.7 %. Massic activities for sample sources had 0.005 % of the sample variability error, which was well within the expanded standard uncertainty of 0.54 % (k=2).

Design, Optimization, and Application of a 3D-Printed Polymer Sample Introduction System for the ICP-MS Analysis of Nanoparticles and Cells

Commonly used sample introduction systems for inductively coupled plasma mass spectrometry (ICP-MS) are generally not well-suited for single particle ICP-MS (spICP-MS) applications due to their high sample requirements and low efficiency. In this study, the first completely 3D-printed, polymer SIS was developed to facilitate spICP-MS analysis. The system is based on a microconcentric pneumatic nebulizer and a single-pass spray chamber with an additional sheath gas flow to further facilitate the transport of larger droplets or particles. The geometry of the system was optimized using numerical simulations. Its aerosol characteristics and operational conditions were studied via optical particle counting and a course of spICP-MS measurements, involving nanodispersions and cell suspensions. In a comparison of the performance of the new and the standard (quartz microconcentric nebulizer plus a double-pass spray chamber) systems, it was found that the new sample introduction system has four times higher particle detection efficiency, significantly better signal-to-noise ratio, provides ca. 20% lower size detection limit, and allows an extension of the upper limit of transportable particle diameters to about 25 µm.

MALTA-Cz: a radiation hard full-size monolithic CMOS sensor with small electrodes on high-resistivity Czochralski substrate

Depleted Monolithic Active Pixel Sensor (DMAPS) sensors developed in the Tower Semiconductor 180 nm CMOS imaging process have been designed in the context of the ATLAS ITk upgrade Phase-II at the HL-LHC and for future collider experiments. The “MALTA-Czochralski (MALTA-Cz)” full size DMAPS sensor has been developed with the goal to demonstrate a radiation hard, thin CMOS sensor with high granularity, high hit-rate capability, fast response time and superior radiation tolerance. The design targets radiation hardness of > 1015 (1 MeV) neq/cm2 and 100 Mrad TID. The sensor shall operate as tracking sensor with a spatial resolution of ≈ 10 μm and be able to cope with hit rates in excess of 100 MHz/cm2 at the LHC bunch crossing frequency of 40 MHz. The 512 × 512 pixel sensor uses small collection electrodes (3.5 μm) to minimize capacitance. The small pixel size (36.4 × 36.4 μm2) provides high spatial resolution. Its asynchronous readout architecture is designed for high hit-rates and fast time response in triggered and trigger-less detector applications. The readout architecture is designed to stream all hit data to the multi-channel output which allows an off-sensor trigger formation and the use of hit-time information for event tagging.The sensor manufacturing has been optimised through process adaptation and special implant designs to allow the manufacturing of small electrode DMAPS on thick high-resistivity p-type Czochralski substrate. The special processing ensures excellent charge collection and charge particle detection efficiency even after a high level of radiation. Furthermore the special implant design and use of a Czochralski substrate improves the sensor's time resolution. This paper presents a summary of sensor design optimisation through process and implant choices and TCAD simulation to model the signal response. Beam and laboratory test results on unirradiated and irradiated sensors have shown excellent detection efficiency after a dose of 2 × 1015 1 MeV neq/cm2. The time resolution of the sensor is measured to be σ = 2 ns.

Status and perspectives of vacuum-based photon detectors

Status and perspectives of vacuum-based photon detectors

High Sensitivity Extended Nano-Coulter Counter for Detection of Viral Particles and Extracellular Vesicles.

We present a chip-based extended nano-Coulter counter (XnCC) that can detect nanoparticles affinity-selected from biological samples with low concentration limit-of-detection that surpasses existing resistive pulse sensors by 2-3 orders of magnitude. The XnCC was engineered to contain 5 in-plane pores each with an effective diameter of 350 nm placed in parallel and can provide high detection efficiency for single particles translocating both hydrodynamically and electrokinetically through these pores. The XnCC was fabricated in cyclic olefin polymer (COP) via nanoinjection molding to allow for high-scale production. The concentration limit-of-detection of the XnCC was 5.5 × 103 particles/mL, which was a 1,100-fold improvement compared to a single in-plane pore device. The application examples of the XnCC included counting affinity selected SARS-CoV-2 viral particles from saliva samples using an aptamer and pillared microchip; the selection/XnCC assay could distinguish the COVID-19(+) saliva samples from those that were COVID-19(-). In the second example, ovarian cancer extracellular vesicles (EVs) were affinity selected using a pillared chip modified with a MUC16 monoclonal antibody. The affinity selection chip coupled with the XnCC was successful in discriminating between patients with high grade serous ovarian cancer and healthy donors using blood plasma as the input sample.

Virus-Host Dynamics in Archaeal Groundwater Biofilms and the Associated Bacterial Community Composition.

Spatial and temporal distribution of lytic viruses in deep groundwater remains unexplored so far. Here, we tackle this gap of knowledge by studying viral infections of Altivir_1_MSI in biofilms dominated by the uncultivated host Candidatus Altiarchaeum hamiconexum sampled from deep anoxic groundwater over a period of four years. Using virus-targeted direct-geneFISH (virusFISH) whose detection efficiency for individual viral particles was 15%, we show a significant and steady increase of virus infections from 2019 to 2022. Based on fluorescence micrographs of individual biofilm flocks, we determined different stages of viral infections in biofilms for single sampling events, demonstrating the progression of infection of biofilms in deep groundwater. Biofilms associated with many host cells undergoing lysis showed a substantial accumulation of filamentous microbes around infected cells probably feeding off host cell debris. Using 16S rRNA gene sequencing across ten individual biofilm flocks from one sampling event, we determined that the associated bacterial community remains relatively constant and was dominated by sulfate-reducing members affiliated with Desulfobacterota. Given the stability of the virus-host interaction in these deep groundwater samples, we postulate that the uncultivated virus-host system described herein represents a suitable model system for studying deep biosphere virus-host interactions in future research endeavors.

The scanning light ion microprobe in Uppsala – Status in 2022

The Scanning Light Ion Microprobe in Uppsala (SLIM-UP) was originally installed during 1989/90. Since then, the microprobe has undergone several minor and major modifications. The present configuration is a re-build of the SLIM-UP, that is now connected to the 5 MV tandem Pelletron® accelerator of the Tandem Laboratory, Uppsala University. We give an overview of the present status of the Uppsala microprobe facility, including a detailed description of the components and a recent resolution test. In addition, we present the most recent technical developments whereby, the system is able to quickly image large area samples, to reliably identify individual microparticles, and to analyse them separately. Optimal parameters for a certain system can be found by simple test measurements on dummy samples. Our test scenario comprises of Fe particles embedded in a light matrix, representing human tissue. We found a good compromise between the required analysis time and particle detection efficiency.

In-site electrophoretic elution of excessive fluorescein isothiocyanate from fluorescent particles in gel for image analysis

去除荧光标记后残余荧光染料可以提高荧光颗粒检测的灵敏度、准确度和效率。该文发展了一种原位电泳洗脱(electrophoretic elution, EE)模型,用于在荧光标记后快速去除多余的荧光探针,实现荧光颗粒的灵敏检测。将牛血清蛋白(BSA)和磁珠(MBs)作为模式蛋白和微颗粒,混合孵育获得MBs-BSA,用异硫氰酸荧光素(FITC)对MBs-BSA标记,得到MBs-BSAFITC复合物。将含有多余FITC的MBs-BSAFITC溶液与低凝聚温度琼脂糖凝胶溶液按1:5的体积比混合,并将混合物凝胶和纯琼脂糖凝胶分段填充到电泳通道中。电泳过程中,利用颗粒尺寸与凝胶孔径的差异来保留MBs-BSAFITC,同时将游离的FITC洗脱。经过30 min的电泳洗脱,通道内多余的FITC清除率达到97.6%,同时目标颗粒荧光信号保留了27.8%。成像系统曝光时间为1.35 s时,电泳洗脱将颗粒与背景的荧光信号比(P/B ratio, PBr)从1.08增加到12.2。CCD相机的曝光时间增加到2.35 s,可以将PBr提高到15.5,可进一步实现对微弱荧光亮点的高灵敏检测。该模型有以下优点:(1)能对颗粒表面非特异性吸附的FITC实现有效洗脱,提高了检测的特异性;(2)能够将97%以上的游离FITC清除;(3) 30 min内能够使凝胶内的背景荧光大幅降低,提高了PBr和检测灵敏度。因此,该方法具有在凝胶中进行基于磁珠/荧光颗粒点的免疫检测、在免疫电泳或凝胶电泳中对蛋白质/核酸条带进行荧光染色等领域的应用潜力。

Improving time and position resolutions of RPC detectors using time over threshold information

INO-ICAL is a proposed underground experiment to study the oscillation parameters of neutrinos by detecting those produced in the atmospheric air showers. The Iron CALorimeter (ICAL) is to have 151 layers of iron plates stacked vertically corresponding to a height of ∼14.5 m, with active detector elements inserted between the iron layers. The iron layers will be magnetized with a maximum magnetic field of 1.5 T to enable the measurement of the charge and momentum of the μ - (or μ +) produced by ν μ (or ν̅ μ ) interactions inside the detector throughout the operation. Resistive Plate Chambers (RPCs) have been chosen as the active detector elements as they are amenable to large area coverage, as well as due to their high particle detection efficiency, long-term performance and low cost of production. The major factors that weigh in on the physics potential of the ICAL detector are the efficiency, position resolution and time resolution of the large area RPCs. A prototype detector called mini-ICAL (with 11 iron layers) was commissioned in order to understand the engineering challenges in building the large-scale electromagnet and its ancillary systems, and also to study the performance of the RPC detectors and readout electronics developed by the INO collaboration. As part of the performance study of the RPC detectors, an attempt is made to improve their position and time resolutions. The designed position resolution for the ICAL detector is of the order of 1 cm and the required time resolution is ∼1 ns. Even a small improvement in the position and time resolution will help to improve the measurements of momentum and directionality of the neutrinos in the ICAL detector. In ICAL detector simulation, where muons traverse in all directions with on average 20 RPC layers, a 30 % improvement in position resolution results in ∼10 % improvement in the momentum resolution at 3 GeV. Due to large iron materials in between two RPCs, the resolution is dominated by the effect of multiple scattering at this momentum. Also for a muon with 10 layer hit, the charge ambiguity reduces from 0.04 % to 0.001 % when the time resolution improves from 1 ns to 0.7 ns. The Time-over-Threshold (ToT) of the RPC pulses is recorded by the readout electronics. ToT is a measure of the pulse width and consequently the pulse amplitude. This information is used to improve the time and position resolution of RPCs and consequently INO's physics potential.

Salt Gradient Control of Translocation Dynamics in a Solid-State Nanopore.

Tuning capture rates and translocation time of analytes in solid-state nanopores are one of the major challenges for their use in detecting and analyzing individual nanoscale objects via ionic current measurements. Here, we report on the use of salt gradient for the fine control of capture-to-translocation dynamics in 300 nm sized SiNx nanopores. We demonstrated a decrease up to a factor of 3 in the electrophoretic speed of nanoparticles at the pore exit along with an over 3-fold increase in particle detection efficiency by subjecting a 5-fold ion concentration difference across the dielectric membrane. The improvement in the sensor performance was elucidated to be a result of the salt-gradient-mediated electric field and electroosmotic flow asymmetry at nanochannel orifices. The present findings can be used to enhance nanopore sensing capability for detecting biomolecules such as amyloids and proteins.

Beam test results of silicon sensor module prototypes for the Phase-2 Upgrade of the CMS Outer Tracker

The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment.

Intermittency analysis of proton numbers in heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider

Local density fluctuations near the QCD critical point has been suggested to exhibit a power-law behavior which can be probed by an intermittency analysis on scaled factorial moment (SFM) in relativistic heavy-ion collisions. The collision energy and centrality dependence of the second-order SFMs are systematically investigated in Au $+$ Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV within the UrQMD model. We estimate the noncritical background in the measurement of intermittency and propose a cumulative variable method to effectively remove the background contributions. We further study the effect of particle detection efficiency by implementing the RHIC (STAR) experimental tracking efficiencies in the UrQMD events. A cell-by-cell method is proposed for experimental application of efficiency corrections on SFM. This work can provide a guidance of background subtraction and efficiency correction for the experimental measurement of intermittency in the search of the QCD critical point in heavy-ion collisions.

A novel high dynamic-range SiPM for scintillator-based hadronic calorimetry

The Analog Hadronic Calorimeter (AHCAL) is one option of highly granular calorimeters optimised with the Particle Flow Algorithm (PFA) and considered for experiments at future lepton colliders. It consists of dense steel plates as absorber interleaved with plastic scintillator tiles, individually read out by Silicon Photomultipliers (SiPMs). A novel SiPM developed by the Novel Device Laboratory (NDL) with an active area of 1 mm2 and a pixel pitch of 12.5 micron[NDL-SiPM-12.5] has been mainly investigated. The characterisation studies include single photon calibration, dynamic range and performance of crosstalk as well as Minimum Ionising Particle (MIP) detection efficiency of a detector unit. Combined tests with a dedicated ASIC (SPIROC2E) for multi-channel SiPMs show that single photon spectra can be obtained, given the relatively small SiPM gain (∼2 × 105). The linearity of the SiPMs in response to incident photons of less than 10,000 (500 MIPs) is within 5% from measurements. Meanwhile, the dark count rate (DCR) is around 2×10-3 Hz at a threshold 0.5 MIP (10 p.e.) and the MIP detection efficiency of a detector unit can be near 95% from the MIP spectrum. These studies indicate the NDL-SiPM-12.5 can be a photosensor candidate for the future scintillator-based hadronic calorimeters.

Measurement of sub-3 nm flame-generated particles using butanol CPCs in boosted conditions

While condensation particle counters (CPCs) are routinely used to measure particle number concentrations in the size range from 3 to 1000 nm, the detection efficiency for sub-3 nm particles remains...

Evaluation of an airborne alpha and beta particle detection capability using an environmental continuous air monitor system

We evaluate the ability of the Canberra Alpha Beta Environmental Continuous Air Monitor (ECAM) to detect and quantify airborne radiological contamination. The ECAM essentially consists of a passively-implanted planar silicon (PIPS) detector near a particulate filter through which outside air is pulled. Three years' worth of background measurements on three different systems were assessed and calibrated to compensate for changing conditions and develop an average background response for the systems. The ECAM was also exposed to several radionuclides of interest, including 235U and 239Pu, to measure the response to alpha and beta particle sources. Both standard calibration sources and custom sources consisting of aqueous radioisotope solutions absorbed into clean filters. The ECAM responses to these sources were then scaled to quantities of interest and injected on the averaged background. Various alarm algorithms were evaluated on the source-injected spectra for minimum detectable air concentration for a given false alarm rate. Even in the worst case, the ECAM was able to detect radionuclides of interest at 10% of the Derived Response Level (DRL) for each isotope based on early-phase Protective Action Guides (PAG). Quantification of the radionuclides was also evaluated for the various algorithms, with mixed results, but overall clearly indicating the optimal algorithms for alpha and beta particle alarm and quantification. Finally, a limited evaluation of the beta particle detection efficiency points to a detection energy threshold of approximately 290keV.