Charged Particle Detection Research Articles

Registration of the auroral near-UV emission by the orbital detector TUS

The TUS detector is a highly sensitive orbital telescope. Due to the polar orbit of the spacecraft, the detector made observations of the UV luminosity of the atmosphere above the aurora oval. Events with intensity variations characteristic of pulsating auroras have been registered. The events are located along the equatorial boundary of the auroral oval and occur during long-term geomagnetic disturbances. Comparison with data from charged particle detectors shows the presence of an increased flux of precipitating high-energy electrons (with energies above 100 keV) simultaneously with UV pulsations.

4D-tracking with digital SiPMs

Silicon Photomultipliers (SiPMs) are the state-of-the-art technology in single-photon detection with solid-state detectors. Single Photon Avalanche Diodes (SPADs), the key element of SiPMs, can now be manufactured in CMOS processes, facilitating the integration of a SPAD array into custom monolithic ASICs. This allows implementing features such as signal digitization, masking, full hit-map readout, noise suppression, and photon counting in a monolithic CMOS chip. The complexity of the off-chip readout chain is thereby reduced.These new features allow new applications for digital SiPMs, such as 4D-tracking of charged particles, where spatial resolutions of the order of 10µm and timestamping with time resolutions of a few tens of ps are required.A prototype of a digital SiPM was designed at DESY using the LFoundry 150nm CMOS technology. Various studies were carried out in the laboratory and at the DESY II test-beam facility to evaluate the sensor performance in Minimum Ionizing Particles (MIPs) detection. The direct detection of charged particles was investigated for bare prototypes and assemblies coupling dSiPMs and thin LYSO crystals. Spatial resolution ∼20µm and a full-system time resolution of ∼50ps are measured using bare dSiPMs in direct MIP detection. Efficiency >99.5%, low noise rate and time resolution <1ns can be reached with the thin radiator coupling.

Exciton-harvesting enabled efficient charged particle detection in zero-dimensional halides

Materials for radiation detection are critically important and urgently demanded in diverse fields, starting from fundamental scientific research to medical diagnostics, homeland security, and environmental monitoring. Low-dimensional halides (LDHs) exhibiting efficient self-trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) have recently shown a great potential as scintillators. However, an overlooked issue of exciton-exciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications. Here, we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional (0D) Cs3Cu2I5:Tl halide single crystals by forming strongly localized Tl-bound excitons. Because of the suppression of non-radiative exciton-exciton interaction, an excellent α/β pulse-shape-discrimination (PSD) figure-of-merit (FoM) factor of 2.64, a superior rejection ratio of 10−9, and a high scintillation yield of 26 000 photons MeV−1 under 5.49 MeV α-ray are achieved in Cs3Cu2I5:Tl single crystals, outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications. Furthermore, a radiation detector prototype based on Cs3Cu2I5:Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications. We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.

Compact Ion Beam System for Fusion Demonstration

We demonstrate a compact ion beam device capable of accelerating H+ and D+ ions up to 75 keV energy, onto a solid target, with sufficient beam current to study fusion reactions. The ion beam system uses a microwave driven plasma source to generate ions that are accelerated to high energy with a direct current (DC) acceleration structure. The plasma source is driven by pulsed microwaves from a solid-state radiofrequency (RF) amplifier, which is impedance matched to the plasma source chamber at the S-band frequency in the range of 2.4–2.5 GHz. The plasma chamber is held at high positive DC potential and is isolated from the impedance matching structure (at ground potential) by a dielectric-filled gap. To facilitate the use of high-energy-particle detectors near the target, the plasma chamber is biased to a high positive voltage, while the target remains grounded. A target loaded with deuterium is used to study D-D fusion and a B4C or LaB6 target is used to study p-11B fusion. Detectors include solid-state charged particle detector and a scintillation fast neutron detector. The complete ion beam system can fit on a laboratory table and is a useful tool for teaching undergraduate and graduate students about the physics of fusion.

Novel indium phosphide charged particle detector characterization with a 120 GeV proton beam

Thin film detectors which incorporate semiconductor materials other than silicon have the potential to build upon their unique material properties and offer advantages such as faster response times, operation at room temperature, and radiation hardness. To explore the possibility, promising candidate materials were selected, and particle tracking detectors were fabricated. An indium phosphide detector with a metal-intrinsic-metal structure has been fabricated for particle tracking. The detector was tested using radioactive sources and a high energy proton beam at Fermi National Accelerator Laboratory. In addition to its simplistic design and fabrication process, the indium phosphide particle detector showed a very fast response time of hundreds of picoseconds for the 120 GeV protons, which are comparable to the ultra-fast silicon detectors. This fast-timing response is attributed to the high electron mobility of indium phosphide. Such material properties can be leveraged to build novel detectors with superlative performance.

Construction and performance test of charged particle detector array for MATE

Construction and performance test of charged particle detector array for MATE

Physical properties of InxSey and CuInSe2 thin films with potential application in radiation detectors

A study of InxSey and CuInSe2 thin films processed by the thermal co-evaporation technique by evaluating its physical properties is carried out. Both InxSey as well as CuInSe2 thin films were synthesized by multi-source thermal co-evaporation technique, using Knudsen-type effusion cells. The optical, structural, electrical, and morphological properties of each film were analyzed in order to determine the feasibility at the formation of a p-CuInSe2/n-InxSey heterojunction. InxSey films exhibited bandgap values in the range of 2.4–2.7 eV which was determined by UV–vis spectroscopic analysis. Vibrational modes associated to In2Se3 as well as Se are presented in the InxSey films according to Raman studies. The irregular morphology of the grains on the InxSey surface, with an average size of 380 nm are related to both In2Se3 and Se materials according to Raman spectroscopy and Scanning Electron Microscopy analysis. The InxSey thin films showed resistivity vales around 10–3 Ω·cm. The Hackee´s figure of Merit (FOMH) analysis supported the physical assumption that InxSey thin films are feasible to be used as window layer in a photovoltaic device because of the high values of FOMH obtained for samples processed at 300 °C. On the other hand, an influence on the morphology of the CuInSe2 films was observed when the films were synthetized at different substrate temperature. Uniform CuInSe2 films with agglomerated cauliflower-like grains with an average size of 1.8 μm were observed by SEM. The presence of binary phases within the CuInSe2 compound were detected through Raman and x-ray characterization. Average crystallite size of 61 nm and microstrain around 2.5 × 10–3 were estimated for the CuInSe2 films through x-ray analysis. According to the physical properties analyzed the InxSey/CuInSe2 semiconductor bilayer can be a suitable candidate for application in photovoltaic devices as well as charged particle detector.

Interstellar Neutral Hydrogen in the Heliosphere: New Horizons Observations in the Context of Models

Interstellar neutral (ISN) hydrogen is the most abundant species in the outer heliosheath and the very local interstellar medium (VLISM). Charge-exchange collisions in the outer heliosheath result in filtration, reducing the ISN hydrogen density inside the heliosphere. Additionally, these atoms are intensively ionized close to the Sun, resulting in a substantial reduction of their density within a few astronomical units from the Sun. The products of this ionization—pickup ions (PUIs)—are detected by charged particle detectors. The Solar Wind Around Pluto instrument on New Horizons provides, for the first time, PUI observations from the distant heliosphere. We analyze the observations collected between 22 and 52 au from the Sun to find the ISN hydrogen density profile and compare the results with predictions from global heliosphere models. We conclude that the density profile derived from the observations is inconsistent with steady-state model predictions. This discrepancy is not explained by time variations close to the Sun and thus may be related to the temporal evolution of the outer boundaries or VLISM conditions. Furthermore, we show that the cold and hot models of ISN hydrogen distribution are not a good approximation closer to the termination shock. Therefore, we recommend a new fiduciary point based on the available New Horizons observations at 40 au from the Sun, at ecliptic direction (285.°62, 1.°94), where the ISN hydrogen density is 0.11 cm−3. The continued operation of New Horizons should give better insight into the source of the discussed discrepancy.

HETEROSTRUCTURED SCINTILLATORS BASED ON ORGANIC SINGLE CRYSTAL GRAINS FOR A HIGH PULSE SHAPE DISCRIMINATION

This article is related to studying the properties and improving the characteristics of the new types of organic heterostructured scintillators as detectors of fast neutrons and short-range charged particles. This research is aimed to find the opportunities to improve the characteristics of the detector, based on a heterostructured scintillation material, and to expand the possibilities of its practical applications, in particular, for the tasks of separate detection of ionizing radiations of different types.

Investigation of triaxial cables and microdetectors in small field dosimetry

Background. Small field dosimetry presents unique challenges with source occlusion, lateral charged particle equilibrium and detector size. As detector volume decreases, signal strength declines while noise increases, deteriorating the signal-to-noise ratio (SNR). This issue may be compounded by triaxial cables connecting detectors to electrometers. However, effects of cables, critical for precision dosimetry, are often overlooked. There is a need to evaluate triaxial cable and detector impacts on SNR in small fields. The purpose of this study is to evaluate the influence of triaxial cables and microdetectors on signal-to-noise ratios in small-field dosimetry. This study also aims to establish the importance of cable quality assurance for measurement accuracy. Methods. Six 9.1 m length triaxial cables from different manufacturers were tested with six microdetectors (microDiamond, PinPoint, EDGE, Plastic scintillator, microSilicon, SRS-Diode). A 6 MV photon beam (TrueBeam) was used, with a water phantom at 5 cm depth with 0.5 × 0.5 cm2 to 10 × 10 cm2 fields at 600 MU min−1. Readings were acquired using cable-detector permutations with a dedicated electrometer (except the scintillator which has its own). Cables had differing connector types, conductor materials, insulation, and diameters. Detectors had various sensitive volumes, materials, typical signals, and bias voltages. Results. Normalized field output correction factors (FOFs) relative differences of 13.4% and 4.6% between the highest and lowest values across triaxial cables for 0.5 × 0.5 cm2 and 1 × 1 cm2 fields, respectively. The maximum difference in FOF between any cable-detector combinations was 0.2% for the smallest field size. No consistent FOF trend was observed across all detectors when increasing cable diameter. Additionally, the non-normalized FOF differences of 0.9% and 0.3% were observed between cables for 0.5 × 0.5 cm2 and 1 × 1 cm2 fields, respectively. Conclusions. Regular triaxial cable quality assurance is critical for precision small field dosimetry. A national protocol is needed to standardize cable evaluations/calibrations, particularly for small signals (<pC) from modern detectors. This could enhance measurement accuracy and treatment delivery with advanced small-field radiotherapy techniques that promise improved patient outcomes. Further studies should expand detector and cable models tested across institutions to establish robust quality control guidelines.

The Charged Particle Detection System of the SRD Module onboard the China Space Station

The radiation field environment outside the Earth varies greatly with space location and the cycle of solar activity, and the radiation environment near the space station’s orbit is much more complex than that on the Earth’s surface. Various high-energy cosmic ray particles and secondary particles produced by them and the bulkhead of the space station greatly impact the health of astronauts and the working conditions of instruments. Each aircraft is always equipped with some dedicated radiation monitoring instruments to assess the exposure risk for astronauts, and to analyze the causes of instrument failures. The Space Radiation Detector Module (SRDM) is working in the China Space Station (CSS) to measure the radiation environment inside, including two parts: the Charged Particle Detection System (CPDS) and the Neutron Detection System (NDS). The CPDS, which is the main content of this paper, contains a detector unit, that consists of three silicon detectors a BGO calorimeter, and the corresponding readout electronics unit of the detector unit. Ground test results show that the detection system can detect various charged particles from hydrogen to nitrogen ions with an energy resolution of less than 15%. The actual measurement results for a period in orbit show that the main types of charged particles in the cabin are protons and α particles, with measured energies ranging from 0.8 to 265.2 MeV for protons and from 1.0 to 61.6 MeV/A for α particles(where A is the mass number), and linear energy density (LET) range mainly from 1.0 to 612.4 keV/μm. The radiation environment data measured in CSS can provide an important reference value for the exposure risk, life science experiments, and the status of instruments on board.

Off-resonance electronic detection and cooling of ions in a Penning trap

We present a non-destructive electronic detector for stored charged particles in a Penning trap that uses a symmetric electrode arrangement for signal pickup and a resonator without tap. This system has advantageous off-resonance features which are demonstrated by means of detection and cooling measurements with highly charged ions in a cryogenic Penning trap. In particular, it allows for particle detection across a wide range of frequencies that is not concomitant with cooling and offers a novel way to tune a trap with the help of non-destructive measurements on large particle ensembles.

Experimental characterization of discrimination capabilities of EJ-276 and EJ-276G read by SiPM by pulse-shape analysis techniques

This work aims at the investigation of the Pulse Shape Discrimination (PSD) capabilities of two very compact detection systems composed of a 3x3x3 cm3 EJ 276 and a 3x3x3 cm3 EJ 276G (the latter green shifted version) plastic scintillators, both coupled to Silicon Photomultiplier (SiPM). The studied systems are supposed to be the basic elementary cell of a new multi-detector for simultaneous detection of neutrons and light charged particles called NArCoS (Neutron Array for Correlation Studies) having both high angular and energy resolution. In this perspective, the results of the experimental qualification of two prototypes with gamma and alpha radioactive sources and in beam tests are reported, in order to characterize the optimum choice for the new device.

Compact Monoenergetic Proton Generator in MeV Region Using NANOGAN

For simple applications, such as the calibration of a charged particle detector, a multi-MeV proton generator may be preferable to cyclotrons or electrostatic accelerators such as Van de Graaff. Thus, a compact proton generating system, consisting of 10Ghz ECR ion source NANOGAN and a deuteron target, was developed at the Research Center for Nuclear Physics at Osaka University. A 3He2+ beam was generated by the NANOGAN with the acceleration voltage of 20∼45 kV in an experiment that utilized the fusion reaction 3He + deuteron (d) → proton(p) + 4He. The monochromatic protons with energies of 14.67 MeV were successfully obtained at the atmosphere side of the target in the experimental setup, when a novel target base with a thin metal foil and Polyimide film window are used.

Self-powered 4 H-SiC charged particle detector with 1 cm2 sensitive area and 0.63% energy resolution

Silicon carbide (SiC) detector, one of important charged particle detectors with good endurance in high-temperature and harsh-radiation environment, is highly demanded for high energy resolution and large sensitive area, but is hardly to acquire for decades. In this paper, a SiC charged particle detector was fabricated using high-quality homogenous epitaxial 4 H-SiC wafer with thickness of 150 μm and in vertical PIN diode structure; high-performance of low dark current (0.60 nA/cm2 within reverse bias of 600 V), large sensitive area (1 cm2) and high energy resolution (0.63%) were successfully achieved; furthermore, the detector was proven as self-powered charged particle detector for high charge collection efficiency of 95.96% and proper energy resolution at a bias voltage of 0 V. We envision that SiC charged particle detector would promote further development of radiation detection and charged particle spectrometer.

Heavy-to-light electron transition enabling real-time spectra detection of charged particles by a biocompatible semiconductor

The current challenge of wearable/implantable personal dosimeters for medical diagnosis and radiotherapy applications is lack of suitable detector materials possessing both excellent detection performance and biocompatibility. Here, we report a solution-grown biocompatible organic single crystalline semiconductor (OSCS), 4-Hydroxyphenylacetic acid (4HPA), achieving real-time spectral detection of charged particles with single-particle sensitivity. Along in-plane direction, two-dimensional anisotropic 4HPA exhibits a large electron drift velocity of 5 × 105 cm s−1 at “radiation-mode” while maintaining a high resistivity of (1.28 ± 0.003) × 1012 Ω·cm at “dark-mode” due to influence of dense π-π overlaps and high-energy L1 level. Therefore, 4HPA detectors exhibit the record spectra detection of charged particles among their organic counterparts, with energy resolution of 36%, (μt)e of (4.91 ± 0.07) × 10−5 cm2 V−1, and detection time down to 3 ms. These detectors also show high X-ray detection sensitivity of 16,612 μC Gyabs−1 cm−3, detection of limit of 20 nGyair s−1, and long-term stability after 690 Gyair irradiation.

Attosecond absorption and reflection spectroscopy of solids

Since their introduction, all-optical spectroscopy techniques based on attosecond radiation have gained the attention of the scientific community because of their energy and time resolution, combined with an easier experimental implementation with respect to other approaches based on charged particle detection. At the present time, almost ten years after the first application to a solid sample, attosecond transient absorption spectroscopy (ATAS) and attosecond transient reflection spectroscopy (ATRS) have established as powerful tools to investigate how electrons can be excited and accelerated in matter with short light pulses, a key requisite to establish ultrafast switches in quantum electronics and overcome the current rate of data processing and information encoding. In this work, we start with a historical overview of the first pioneering experiments to then introduce the fundamentals of both techniques. We conclude by discussing the current challenges and the possible future developments that are expected to bring ATAS and ATRS beyond their state of the art.

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.

Design and performance of the front-end electronics of the charged particle detectors of PADME experiment

The PADME experiment at LNF-INFN employs positron-on-target-annihilationto search for new light particles. Crucial parts of the experiment are the chargedparticle detectors, composed of plastic scintillator bars with light transmittedby wavelength shifting fibers to silicon photomultipliers (SiPMs). The location ofthe detector — close to a turbomolecular pump, inside a vacuum tank, and exposedto 0.5 T magnetic field — has driven the design of custom modular SiPM front-endand power supply electronics. The design of the system and its performance, confirmingthe desired sub-ns resolution on the reconstructed particle flying times, is shownand discussed.

Development of a mosaic-type array formed by Si photodiodes for charged-particle detection in heavy-ion collisions

Silicon (Si) detectors find widespread application in heavy-ion collisions. In order to achieve a position-sensitive charged-particle detection with a relatively low cost, we have developed a mosaic-type array based on off-the-shelf Si photodiodes (Hamamatsu S13955-01). Its high modularity allows one to modify the geometric configuration of the array according to specific experimental requirements. In this contribution, characteristics of the photodiode tested with α source and experimental results of the α-decay spectroscopy are presented.