Photomultiplier Research Articles

Comparison between silicon photomultiplier-based and conventional PET/CT in patients with suspected lung cancer\u2014a pilot study

BackgroundLung cancer is one of the most common cancers in the world. Early detection and correct staging are fundamental for treatment and prognosis. Positron emission tomography with computed tomography (PET/CT) is recommended clinically. Silicon (Si) photomultiplier (PM)-based PET technology and new reconstruction algorithms are hoped to increase the detection of small lesions and enable earlier detection of pathologies including metastatic spread. The aim of this study was to compare the diagnostic performance of a SiPM-based PET/CT (including a new block-sequential regularization expectation maximization (BSREM) reconstruction algorithm) with a conventional PM-based PET/CT including a conventional ordered subset expectation maximization (OSEM) reconstruction algorithm. The focus was patients admitted for 18F-fluorodeoxyglucose (FDG) PET/CT for initial diagnosis and staging of suspected lung cancer. Patients were scanned on both a SiPM-based PET/CT (Discovery MI; GE Healthcare, Milwaukee, MI, USA) and a PM-based PET/CT (Discovery 690; GE Healthcare, Milwaukee, MI, USA). Standardized uptake values (SUV) and image interpretation were compared between the two systems. Image interpretations were further compared with histopathology when available.ResultsSeventeen patients referred for suspected lung cancer were included in our single injection, dual imaging study. No statically significant differences in SUVmax of suspected malignant primary tumours were found between the two PET/CT systems. SUVmax in suspected malignant intrathoracic lymph nodes was 10% higher on the SiPM-based system (p = 0.026). Good consistency (14/17 cases) between the PET/CT systems were found when comparing simplified TNM staging. The available histology results did not find any obvious differences between the systems.ConclusionIn a clinical setting, the new SiPM-based PET/CT system with a new BSREM reconstruction algorithm provided a higher SUVmax for suspected lymph node metastases compared to the PM-based system. However, no improvement in lung cancer detection was seen.

A Compton polarimeter using scintillators read out with MPPCs through Citiroc ASIC

In recent years, a number of purpose-built scintillator-based polarimeters have studied bright astronomical sources for the first time in the hard X-ray band (tens to hundreds of keV). The addition of polarimetry can help data interpretation by resolving model-dependent degeneracies. The typical instrument approach is that incident X-rays scatter off a plastic scintillator into an adjacent scintillator cell. In all missions to date, the scintillators are read out using traditional vacuum tube photo-multipliers (PMTs). The advent of solid-state PMTs ("silicon PM" or "MPPC") is attractive for space-based instruments since the devices are compact, robust and require a low bias voltage. We have characterised the plastic scintillator, EJ-248M, optically coupled to a multi-pixel photon counter (MPPC) and read out with the Citiroc ASIC. A light-yield of 1.6 photoelectrons/keV has been obtained, with a low energy detection threshold of $\lesssim$5 keV at room temperature. We have also constructed an MPPC-based polarimeter-demonstrator in order to investigate the feasibility of such an approach for future instruments. Incident X-rays scatter from a plastic-scintillator bar to surrounding cerium-doped GAGG (Gadolinium Aluminium Gallium Garnet) scintillators yielding time-coincident signals in the scintillators. We have determined the polarimetric response of this set-up using both unpolarised and polarised $\sim$50 keV X-rays. We observe a clear asymmetry in the GAGG counting rates for the polarised beam. The low-energy detection threshold in the plastic scintillator can be further reduced using a coincidence technique. The demonstrated polarimeter design shows promise as a space-based Compton polarimeter and we discuss ways in which our polarimeter can be adapted for such a mission.

Silicon Photo-Multipliers

The measurement of single or few photons with a time resolution of 1 ns or below is an experimental technique with many applications in research, medicine and industry. Until recently, vacuum photo-multipliers (PMTs) dominated this field. In the 1990s avalanche photo-diodes came into use, and in the last decade solid-state photo-multipliers (SSPMs) have replaced PMTs in many applications. In most cases early samples, not yet optimised for the specific application, have been used. In the meantime industry and research institutes have significantly improved the performance of SSPMs.

Efficient design of a ∅2×2 inch NaI(Tl) scintillation detector coupled with a SiPM in an aquatic environment

Abstract After the Fukushima accident in 2011, there has been increased public concern about radioactive contamination of water resources through fallout in neighboring countries. However, there is still no available initial response system that can promptly detect radionuclides. The purpose of this research is to develop the most efficient gamma spectrometer to monitor radionuclides in an aquatic environment. We chose a thallium-doped sodium iodide (NaI(Tl)) scintillator readout with a silicon photo multiplier (SiPM) due to its compactness and low operating voltage. Three types of a scintillation detector were tested. One was composed of a scintillator and a photomultiplier tube (PMT) as a reference; another system consisted of a scintillator and an array of SiPMs with a light guide; and the other was a scintillator directly coupled with an array of SiPMs. Among the SiPM-based detectors, the direct coupling system showed the best energy resolution at all energy peaks. It achieved 9.76% energy resolution for a 662 keV gamma ray. Through additional experiments and a simulation, we proved that the light guide degraded energy resolution with increasing statistical uncertainty. The results indicated that the SiPM-based scintillation detector with no light guide is the most efficient design for monitoring radionuclides in an aquatic environment.

Study of the light response of an arch-shaped scintillator with direct coupling to a Silicon Photomultiplier readout

We report about a study of the light response of a solid polystyrene-based scintillator with an arch shaped geometry, directly coupled to Silicon Photo Multiplier sensors for the light readout. This geometry is relevant for the design of a novel borehole detector for “muography” applications in Civil Engineering, Geology or Archaeology. The scintillator response has been investigated using a dedicated experimental set-up based on the detection of cosmic ray muons. Configurations that use reflecting and diffusive materials have been tested, as well as configurations with a cover specifically designed to enclose and protect the scintillator. The results found a good compromise between the light response and an easy solution for the detector assembly.

Prospective scintillation electron detectors for S(T)EM based on garnet film scintillators.

The performance of a scintillation electron detector for a scanning electron microscope and/or a scanning transmission electron microscope (S(T)EM) based on new epitaxial garnet film scintillators was explored. The LuGAGG:Ce and LuGAGG:Ce,Mg film scintillators with chemical formula (Ce0.01 Lu0.27 Gd0.74 )3-w Mgw (Ga2.48 Al2.46 )O12 were prepared and their cathodoluminescence (CL) and optical properties were studied and compared with the properties of current standard bulk single crystal YAG:Ce and YAP:Ce scintillators. More specifically, CL decay characteristics, CL emission spectra, CL intensities, optical absorption coefficients, and the refractive indices of the mentioned scintillators were measured. Furthermore, electron interaction volumes with absorbed energy distributions, photomultiplier (PMT) photocathode matchings, modulation transfer functions (MTF), and the photon transport efficiencies of scintillation detectors with the mentioned scintillators were calculated. A CL decay time for the LuGAGG:Ce,Mg film scintillator as low as 28 ns with an afterglow of only 0.02% at 1 μs after the e-beam excitation was observed. As determined from calculated MTFs, the scintillation detectors with the new film scintillators lose contrast transfer ability above 0.6 lp/pixel, while the currently commonly used YAG:Ce single crystal scintillators already do so above 0.1 lp/pixel. It was also calculated that the new studied film scintillators have an 8% higher photon transfer efficiency, even for a simple disk shape compared with the standard bulk single crystal YAG:Ce scintillator. The studied LuGAGG:Ce,Mg epitaxial garnet film scintillators were evaluated as prospective fast scintillators for electron detectors, not only in S(T)EM but also in other e-beam devices.

The electronics of the energy plane of the NEXT-White detector

This paper describes the electronics of NEXT-White (NEW) detector PMT plane, a high pressure xenon TPC with electroluminescent amplification (HPXe-EL) currently operating at the Laboratorio Subterráneo de Canfranc (LSC) in Huesca, Spain. In NEXT-White the energy of the event is measured by a plane of photomultipliers (PMTs) located behind a transparent cathode. The PMTs are Hamamatsu R11410-10 chosen due to their low radioactivity. The electronics have been designed and implemented to fulfill strict requirements: an overall energy resolution below 1% and a radiopurity budget of 20 mBq unit−1 in the chain of 214Bi . All the components and materials have been carefully screened to assure a low radioactivity level and at the same time meet the required front-end electronics specifications. In order to reduce low frequency noise effects and enhance detector safety a grounded cathode connection has been used for the PMTs. This implies an AC-coupled readout and baseline variations in the PMT signals. A detailed description of the electronics and a novel approach based on a digital baseline restoration to obtain a linear response and handle AC coupling effects is presented. The final PMT channel design has been characterized with linearity better than 0.4% and noise below 0.4mV.

Square superlattice pattern by interaction of surface discharge in gas discharge

We report on a square super-lattice pattern by interaction of surface discharge with the applied voltage increasing in a dielectric barrier discharge system. The pattern consists of bright spots, bright lines, and dim spots. The spatio-temporal dynamics of the pattern is studied by photomultiplier (PMT), high speed video camera and normal camera. Results show that the bright spots discharge several times during each half cycle and they are formed by volume discharge (VD), bright line was formed by superposition of the surface discharges (SDs) over a long period of time, and the dim spots are consist of four small spots. The dim spots are formed by the repulsion of SDs. The light intensity of the bright and dim spots of the patch was compared and it was found that the ratio of the light intensity of the bright spot to the dark spot was about 10. The measurement of the emission spectroscopy show the parameters of the bright spots are different from that of the bright lines and dim spots, the discharge type of bright spots an dim spots is different, and reflects that the dim spots are formed by the interaction of SDs. The formation of the pattern is explained by the wall charge theory.

Selecting and designing the front-end amplifier for high-gain photomultiplier detectors with optimal timing performance

High-gain photomultiplier detectors are employed in an increasing number of applications in different fields to evaluate with great accuracy the occurrence time of light flashes composed by few or even single photons. Examples of these application fields are medical imaging, astroparticle and high energy physics, laser spectroscopy and LIDAR. To fulfill a good single photon timing accuracy, in the range of few hundreds of picoseconds, not only detectors with intrinsic excellent timing resolution (photomultiplier tubes, microchannel plated detectors, silicon photo multipliers, etc.) must be used, but the very first front-end amplifier (FEA) stage, used to read-out the detector, must also be carefully chosen and designed. We compare here three commonly used solutions for the FEA, from the point of view of the best achievable timing resolution: the charge sensitive amplifier (CSA), the voltage amplifier (VA) and the current buffer (CB). The results show that the CSA solution is limited in terms of frequency response by the usually large equivalent capacitance of the detector and that, surprisingly, the presence of the parasitic inductance L , due to interconnection detector–FEA, has a noise shaping effect which favorably affects the timing accuracy of the CB over the VA configuration. To support this study, simulations of simple implementations of the compared FEA solutions have been performed, under the same conditions. Moreover, with reference to a given detector and to a particular value of L , we show how the best timing accuracy of the CB is obtained by selecting an appropriate combination of input resistance and bandwidth of the FEA. • Design issues of the Front-end amplifier of photomultipliers for best timing accuracy. • Comparative study of three classical architectures for the Front-end amplifier. • Effect of the interconnection parasitic inductance L on the maximum timing resolution. • An optimal combination of Front-end parameters can be found for best timing accuracy.

On the design of experiments based on plastic scintillators using GEANT4 simulations

Plastic scintillators are widely used as particle detectors in many fields, mainly, medicine, particle physics and astrophysics. Traditionally, they are coupled to a photo-multiplier (PMT) but now silicon photo-multipliers (SiPM) are evolving as a promising robust alternative, specially in space born experiments since plastic scintillators may be a light option for low Earth orbit missions. Therefore it is timely to make a new analysis of the optimal design for experiments based on plastic scintillators in realistic conditions in such a configuration.We analyze here their response to an isotropic flux of electron and proton primaries in the energy range from 1 MeV to 1 GeV, a typical scenario for cosmic ray or space weather experiments, through detailed GEANT4 simulations. First, we focus on the effect of increasing the ratio between the plastic volume and the area of the photo-detector itself and, second, on the benefits of using a reflective coating around the plastic, the most common technique to increase light collection efficiency. In order to achieve a general approach, it is necessary to consider several detector setups. Therefore, we have performed a full set of simulations using the highly tested GEANT4 simulation tool: several parameters have been analyzed such as the energy lost in the coating, the deposited energy in the scintillator, the optical absorption, the fraction of scintillation photons that are not detected, the light collection at the photo-detector, the pulse shape and its time parameters and finally, other design parameters as the surface roughness, the coating reflectivity and the case of a scintillator with two decay components. This work could serve as a guide on the design of future experiments based on the use of plastic scintillators.

Robustness studies of the photomultipliers reading out TileCal, the central hadron calorimeter of the ATLAS experiment

Abstract TileCal, the hadron calorimeter of the ATLAS experiment at LHC, is a 10000 channel detector readout by photomultipliers (PMTs). A challenging goal is to understand whether the full sample of PMTs installed at the beginning of the ATLAS detector operation can be used until completion of the High-Luminosity Large Hadron Collider (HL-LHC) program or not. For this reason, a reliable study of the PMT robustness against ageing is required. Detailed studies modelling the PMT response variation as a function of the integrated anode charge were done.

Deep Learning for Signal and Background Discrimination in Liquid based Neutrino Experiment

In high energy physics experiments, efficient data analysis tools are required to extract interesting information from the massive data. For large-scale liquid-based neutrino experiments, neutrino signals are usually overwhelmed in huge backgrounds. By constructing a liquid neutrino detector toy model, we generate simulation data in Geant4 [1] and run reconstruction for signal background discrimination. The low-level Photo Multipliers (PMT) hits are also projected to a 2D plane to create visualization outputs for classification. With the 2D images as input, we use the Convolutional Neural Network (CNN) as a specific application, which has shown remarkable performance in signal and background discrimination and outperforms those with high-level reconstruction outputs. The method is expected to be used in the neutrino experiments such as JUNO with further study.

Radiation Damage Tests on Diamond and Scintillation Detector Components for the ITER Radial Neutron Camera

During the International Thermonuclear Experimental Reactor (ITER) reactor operation time, the plasma will give rise to high energy neutron and gamma flux, and this intense radiation field will result in serious radiation damage and activation effects on various detectors components. In this paper, neutron detector candidates for the ITER radial neutron camera (RNC), i.e., scintillator components [crystal and plastic scintillators, optical windows, and photomultipliers (PMTs)] and single-crystal diamond detectors, were investigated to establish their radiation hardness and stability under gamma irradiation. Radiation test was carried out at the Italian National Agency for New Technologies, Energy and Sustainable Economic Development Calliope plant (Casaccia R.C., Rome, Italy). The facility is a pool-type irradiation plant equipped with a 60Co source (energy = 1.25 MeV). Gamma radiation tests were performed in the dark and at room temperature for different total absorbed doses, as required for the application in ITER RNC. Scintillators, PMTs, and optical windows were irradiated up to around 100-kGy absorbed dose, while single-crystal diamond detectors up to around 5 MGy. Scintillators and optical windows transmittance measurements were performed in the UV-VIS range (300–700 nm), paying particular attention to the behavior at 390 and 420 nm (scintillating emission wavelengths). Samples were measured in the dark before and after irradiation and their performances were monitored at room temperature for some weeks in order to study the damage recovery in different conditions. For plastic scintillators, photobleaching and optical bleaching followed by thermal annealing processes in air were made to reduce the radiation damage. Quantum efficiency measurements were performed on the PMTs, and the pulse-height spectra and pulse shape capability of the scintillators were investigated by using gamma and neutron sources. The most relevant results of this paper concern the radiation damage observed in scintillators and diamond detectors. The crystalline scintillator sample showed much less radiation resistance than plastic scintillators. A strong damage to the silver deposition of the diamond contacts was observed already at 1.0 MGy, almost leading to contact destruction at 4.7 MGy.

Position-sensitive plastic scintillator detector with WLS-fiber readout

In this paper, the design, construction, simulation, and performance of a position-sensitive plastic scintillator detector are presented. The readout of the detector uses wavelength-shifting fibers coupled with multi-anode photomultipliers (PMTs) for the x- and y-dimensions. After calibrating the multi-anode PMTs, a two-dimensional projection image of the square scintillator telescope hit by cosmic muons is demonstrated. By performing a cosmic test with the Micromegas telescope, the position resolution of the detector was determined to reach approximately 8.6 mm, which is close to the value obtained in physical simulation.

Focal plane detector optical readout

A preliminary study of an alternative solution for the optical detection and tracking of the ions in the MAGNEX focal plane detector for the NUMEN project is presented. The tracks of the ions are sampled by means of the light that they produce through a scintillating gas, which is collected by arrays of Silicon Photo Multiplier suitably arranged. A complete Geant4 simulation is under development in order to correlate detector geometry, characteristics of the gas and light collection efficiency. Fast timing performance could be achieved through a completely digital (on-off) read-out system of the light sensors and a position reconstruction algorithm.

A Quantum Random Number Generator Based on the 100-Mbit/s Poisson Photocount Statistics

A quantum random number generator is experimentally realized. The initial randomness source is a sequence of photocounts from quasi-single-photon radiation detected with a SiPM (Silicon Photo Multiplier) silicon avalanche detector array. The use of a SiPM provides a reliable control of the quantum nature of the Poisson photocount statistics. A special algorithm with nonexponential complexity allows one to extract from the Poisson process all the randomness contained in it, namely, a random uniform sequence of 0 and 1.

English

This research presents the design of a simple and compact yet sensitive gamma detection system which finds optimal utility in student research and demonstration purposes. The design is based on an Avalanche Photodiode (APD), a compact solid-state device. It was argued that, by the virtue of its concise size, simplicity and lower cost, an APD based gamma detection system is a better alternative in these applications as compared to the high-cost and complex Photomultiplier (PMT) based detector systems. This paper provides the basic working details of our design and preliminary test results. Key words: Avalanche photodiode (APD), gamma spectroscopy, scintillator. &nbsp

A compact and low-cost laser induced fluorescence detector with silicon based photodetector assembly for capillary flow systems

A compact and low-cost laser induced fluorescence (LIF) detector based on confocal structure for capillary flow systems was developed and applied for analysis of Her2 protein on single Hela cells. A low-power and low-cost 450 nm laser diode (LD) instead of a high quality laser was used as excitation light source. A compact optical design together with shortened optical path length improved the optical efficiency and detection sensitivity. A superior silicon based photodetector assembly was used for fluorescence detection instead of a photomultiplier (PMT). The limit of detection (LOD) for fluorescein sodium was 3 × 10–12 M or 165 fluorescein molecules in detection volume measured on a homemade capillary electroosmotic driven (EOD)-LIF system, which was similar to commercial LIFs. Compared to commercial LIFs, the whole volume of our LIF was reduced to 1/2–1/3, and the cost was less than 1/3 of them.

The MONDO Detector Prototype Development and Test: Steps Toward an SPAD-CMOS-Based Integrated Readout (SBAM Sensor)

The MOnitor for Neutron Dose in hadrOntherapy (MONDO) project addresses the technical challenges posed by a neutron tracker detector aiming for a high detection efficiency and a good backtracking precision. The project aims to develop a tracking device capable of fully reconstructing the four momentum of fast and ultrafast secondary neutrons produced, e.g., in particle therapy (PT) treatments or in other physical processes. The MONDO tracker uses, as active material, squared scintillating fibers readout by dedicated CMOS-based digital single-photon avalanche diode (SPAD) array sensors. The expected light output, when operating in neutron monitoring applications, was experimentally evaluated in order to optimize the design of the MONDO detector readout. A small detector prototype ( $4 \times 4 \times 4.8$ cm) has been built and tested at a test beam facility. The detection capabilities have been measured using a traditional photomultiplier (PMT) and a particle beam of 450-MeV electrons crossing a single layer of fibers. The observed number of photoelectrons in this case is (7.2 ± 1.4). A detector prototype was also tested with an SPAD-based SBAM (SPAD-Based Acquisition readout for MONDO experiment) sensor ( SPADnet-I ) to study the tracking performances. SBAM is a novel sensor developed to match the need of high single-photon detection efficiency and high spatial resolution and compactness. The sensor expected performance is discussed in view of an operation tailored for PT applications. In this contribution, we also report the results of a simulation performed to optimize the full MONDO detector layout.

Operation of Inertial Electrostatic Confinement Fusion (IECF) Device Using Different Gases

An optical signal of IEC plasma using different gases has been registered by means of an optical fiber and photomultiplier (PMT). The light passing through the fiber is directed to the entrance window of a photomultiplier (PMT, Hamamatsu R955), connected to the digital scope. The discharge current of plasma discharge has been recorded using current probe. The X-ray emission in IEC plasma device was investigated by employing time-resolved detector.