Detector Setup Research Articles

Development and performance studies of a real size Resistive Plate Chamber tested at GIF＋＋, CERN for CBM-MuCh at FAIR, Germany

In the year 2016, Resistive Plate Chambers (RPCs) were proposed to be used as muon detectors in the 3rd and 4th stations of the Muon Chamber (MuCh) detector set-up of the under construction Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. Since then, sincere efforts are being given to develop suitable detectors for this purpose with major challenges being the capability to handle high particle rates and perform well under harsh radiation environments. We have developed and tested a real size RPC along with its dedicated PCB and electronics read-out chain in GIF＋＋ under intense photon flux for its muon detection capability. In this manuscript, we have presented the test results of the RPC tested during November-2021 beam time in GIF＋＋, CERN, Switzerland.

High resolution 2D plastic scintillator detectors for radiotherapy departments

Abstract Introduction Plastic scintillation detectors (PSD) have been developed for over four decades and are widely used in a variety of fields, but one can find relatively few reports of their clinical use compared to other dosimetric solutions. Material and methods The inexpensive detector setup made of a Saint-Gobain BC-400 plastic scintillator and commercially available on the market CMOS-based DSLR Pentax camera was investigated. Build PSD detectors were irradiated with 6, 10 and 15 MV flattening filtered (FF) and 6 and 10 MV flattening filter free (FFF) photon beams using a clinical linear accelerator. Data were processed using Matlab software to remove background and artefacts. A comparison of the spatial resolution parameters to the Gafchromic EBT3 films was performed. Results Average dose difference between TPS and PSD was 1.1%. The measured spatial resolution was 0.29 mm, and it differed from the film by 1.1%. MTF50 for PSD was 0.57 mm higher than the Gafchromic film. Signal to dose fit function with an R-square equal to 0.999 was established. The standard deviation of mean pixels value for a series of measurements was below 0.1%, for variable dose rate dependence was below 0.6% and for different energies 1.1%. It was demonstrated that such a setup allows a satisfactory signal-to-dose dependence and provides high spatial resolution at an affordable price compared to a 2D ion chamber or a diode detector array. Moreover, PSDs are reusable and provide a simple readout compared to Gafchromic films commonly used in radiotherapy departments. Conclusions Variable parameters of the camera allow to select signal values at the optimal level. The system presented excellent signal stability, high image resolution and a simple signal-to-dose relationship which encourages further work to investigate PSDs for use in radiation therapy departments.

Evaluation of a modular all-in-one high-resolution PET detector and readout electronics setup

Objective. The all-in-one solution and modularity of the C13500 series TOF-PET detector modules (Hamamatsu Photonics K.K., Hamamatsu, Japan) make them a highly attractive candidate for the development of positron emission tomography (PET) systems. However, the commercially available portfolio targets clinical whole-body PET systems with a scintillation crystal cross area of 3.1 × 3.1 mm2. To extend the modules for high resolution (preclinical or organ specific) systems, the support for smaller scintillation crystals is required. Approach. In this work, a PET detector was developed based on the TOF-PET modules using a light sharing approach, 16 × 16 lutetium oxyorthosilicate (LSO) scintillation crystals with a size of 1.51 × 1.51 × 10.00 mm3 readout with 8 × 8 photosensor channels of size 3.0 × 3.0 mm2. In addition to hardware and software development, the optimized parameter settings for the adapted configuration were evaluated. Main Results. A factor of two in amplification of the analog signal compared to the minimum gain setting was necessary for an accurate crystal identification (peak-to-valley ratio 14.9 ± 5.9). A further increase to a factor of three was not determined as optimum as the time over threshold duration, thus pile-up probability, increased from 1032.1 ± 109.5 to 1789.5 ± 218.5 ns (photopeak position). With this amplification a full width at half maximum (FWHM) energy resolution of 14.1 ± 2.0% and a high linearity of the energy detection was obtained. A FWHM coincidence resolving time (CRT) of 313 ps was achieved by using a low timing threshold, increasing the bandwidth of the front-end circuit and using a narrow ± 1σ energy window. To approximately double the sensitivity and reduce the power consumption, the timing parameters were adjusted resulting in a FWHM CRT of 354 ps (±2σ). Significance. Based on the results obtained with the proof-of-concept detector setup, we confirm the modularity and flexibility of the all-in-one TOF-PET detector modules for the future development of application-specific high-resolution PET systems.

Coexistence of single-particle and collective excitation in Ni61

The high spin states in 61 Ni have been studied using the fusion evaporation reaction, Ti( $^{14}$C,3n) $^{61}$Ni at an incident beam energy of 40 MeV. A Compton suppressed multi-HPGe detector setup, consisting of six Clover detectors and three single crystal HPGe detectors was used to detect the de-exciting $\gamma$ rays from the excited states. The level scheme has been extended up to an excitation energy of 12.8 MeV and a tentative J$_{\pi}$ = 35/2$^+$ . The low-lying negative parity levels are found to be generated by single particle excitation within the f p shell and also excitations to the g$_{9/2}$ orbitals as explained well with shell model calculations using the GXPF1Br+V M U (modified) interaction. Two rotational structure of regular E2 sequences with small to moderate axial deformation have been established at higher excitation energy. Most interestingly, two sequences of M1 transitions are reported for the first time and described as magnetic rotational bands. The shears mechanism for both the bands can be described satisfactorily by the geometrical model. The shell model calculation involving the cross shell excitation beyond the fp shell well reproduce the M1 and E2 sequences. The shell model predicted B(M1) values for the magnetic rotational band B1 show the decreasing trend with spin as expected with closing of the shears.

Very-high- and ultrahigh-frequency electric-field detection using high angular momentum Rydberg states

We demonstrate resonant detection of rf electric fields from 240 to 900 MHz (very high frequency to ultrahigh frequency) using electromagnetically induced transparency to measure orbital angular momentum $L=3\ensuremath{\rightarrow}{L}^{\ensuremath{'}}=4$ Rydberg transitions. These Rydberg states are accessible with three-photon infrared optical excitation. By resonantly detecting rf in the electrically small regime, these states enable a new class of atomic receivers. We find good agreement between measured spectra and predictions of quantum defect theory for principal quantum numbers $n=45$ to 70. Using a superhetrodyne detection setup, we measure the noise floor at $n=50$ to be $13\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{V}/(\mathrm{m}\sqrt{\mathrm{Hz}})$. Additionally, we utilize data and a numerical model incorporating a five-level master equation solution to estimate the fundamental sensitivity limits of our system.

In-flight recoil separators RITU and MARA and the standard detector setups

In-flight recoil separators RITU and MARA at Jyväskylä Accelerator Laboratory are complementary devices to separate the fusion-evaporation residues from the primary beam and other reaction products. The nuclear-structure-research program at Jyväskylä utilizes these separators and the detector setups shared between the separators to identify weak reaction channels and extract nuclear-structure information via decay experiments and in-beam spectroscopic studies. For example the very weak N∼Z nuclei are studied in-beam by using β-decay tagging method (Tuike scintillator) enhanced with the mass selection (MARA) and charge particle-evaporation veto (JYTube).

Quantifying the Simulation–Reality Gap for Deep Learning-Based Drone Detection

The detection of drones or unmanned aerial vehicles is a crucial component in protecting safety-critical infrastructures and maintaining privacy for individuals and organizations. The widespread use of optical sensors for perimeter surveillance has made optical sensors a popular choice for data collection in the context of drone detection. However, efficiently processing the obtained sensor data poses a significant challenge. Even though deep learning-based object detection models have shown promising results, their effectiveness depends on large amounts of annotated training data, which is time consuming and resource intensive to acquire. Therefore, this work investigates the applicability of synthetically generated data obtained through physically realistic simulations based on three-dimensional environments for deep learning-based drone detection. Specifically, we introduce a novel three-dimensional simulation approach built on Unreal Engine and Microsoft AirSim for generating synthetic drone data. Furthermore, we quantify the respective simulation–reality gap and evaluate established techniques for mitigating this gap by systematically exploring different compositions of real and synthetic data. Additionally, we analyze the adaptation of the simulation setup as part of a feedback loop-based training strategy and highlight the benefits of a simulation-based training setup for image-based drone detection, compared to a training strategy relying exclusively on real-world data.

Method for Rapid Detection of Bacteria Using Magnetic Nanoparticle Aggregates

A novel method for the rapid detection of bacteria in the liquid phase for point-of-care testing was developed using magnetic nanoparticles (MNPs) conjugated with antibodies. We utilized the magnetic characteristic that the magnetic susceptibility decreases when the magnetism of MNP aggregate changes from ferromagnetism to superparamagnetism after bacteria bind to MNPs through an antigen-antibody reaction (Nanomag-D, 500 nmφ, 0.2 μl/sample). The magnetic susceptibility of Fusobacterium nucleatum samples was measured using a lab-made detection setup. We found that the susceptibility depends on the concentration of Fusobacterium nucleatum with optical density (OD) values ranging from 10-4 to 1 (i.e. 8 × 104 ~ 8 × 108 CFU/ml). In addition, the detection time was only about 49 seconds, which shows promise for point-of-care testing.

Apparatus development for detecting the freshness of chicken meat using TCS 3200, PH-98108, and MOS gas sensors

Meat can be determined as a muscle that has entered a rigour mortis state. Due to its high nutritional content, the quality of chicken meat quickly decreased. The changes in meat colour, pH, and metabolite gas production, especially ammonia and hydrogen sulfide, are the typical indicators for meat degradation. This research aimed to design and build an apparatus to evaluate the freshness of the chicken meat displayed for sale or storage. In the following study, four different sensors, including TCS 3200 colour sensor, Metal Oxide Semiconductor (MOS) gas sensors (MQ 136, MQ 137), and PH-98108 sensors, were assembled with the aid of a microcontroller and personal computer to become a meat freshness detection apparatus. After being calibrated, the apparatus was then used to evaluate the freshness of the chicken meat sample. The results indicated that the apparatus showed satisfactory performance in detecting the freshness of the chicken meat sample. This apparatus was movable, simple, cheap, easy to operate, and suitable to be used by meat sellers or related institutions. The sensors used were capable of detecting the changes in colour, pH, NH3 gas, and H2S of the sample. The parameters of L*, b*, pH, H2S, and NH3 gas effectively detected the freshness of chicken meat. After 12 hrs of storage, the values of L*, b*, pH, H2S, and NH3 gas of the sample were 50.34, 17.26, 6.59, 134.08 ppm, and 42.34 ppm, respectively.

A spatially resolved elemental nanodomain organization within acidocalcisomes in Trypanosoma cruzi

How are ions distributed in the three-dimensional (3D) volume confined in a nanoscale compartment? Regulation of ionic flow in the intracellular milieu has been explained by different theoretical models and experimentally demonstrated for several compartments with microscale dimensions. Most of these models predict a homogeneous distribution of ions seconds or milliseconds after an initial diffusion step formed at the ion translocation site, leaving open questions when it comes to ion/element distribution in spaces/compartments with nanoscale dimensions. Due to the influence of compartment size on the regulation of ionic flow, theoretical variations of classical models have been proposed, suggesting heterogeneous distributions of ions/elements within nanoscale compartments. Nonetheless, such assumptions have not been fully proven for the 3D volume of an organelle. In this work, we used a combination of cutting-edge electron microscopy techniques to map the 3D distribution of diffusible elements within the whole volume of acidocalcisomes in trypanosomes. Cryofixed cells were analyzed by scanning transmission electron microscopy tomography combined with elemental mapping using a high-performance setup of X-ray detectors. Results showed the existence of elemental nanodomains within the acidocalcisomes, where cationic elements display a self-excluding pattern. These were validated by Pearson correlation analysis and in silico molecular dynamic simulations. Formation of element domains within the 3D space of an organelle is demonstrated. Distribution patterns that support the electrodiffusion theory proposed for nanophysiology models have been found. The experimental pipeline shown here can be applied to a variety of models where ion mobilization plays a crucial role in physiological processes.

Quadruple UV LED Array for Facile, Portable, and Online Intrinsic Fluorescent Imaging of Protein in a Whole Gel Electrophoresis Chip.

Intrinsic fluorescence imaging (IFI) has been used for the stain-free detection of proteins in slab gel. However, complicated detection setups and small irradiation area limited the development of facile, online, and portable imaging of the whole slab gel. We here designed a quadruple UV LED array to produce even and powerful area light for direct irradiation of gel electrophoresis chip (GEC) at 275 nm. In addition, we only used a filter of 365 nm, a UV camera lens, and a CCD for IFI detection. We integrated the simple detection setup with the small GEC to construct the IFI-GEC device with a portable size of 15 × 15 × 38 cm. We detected three model proteins to demonstrate the good evenness of the LED array and the online imaging of the whole GEC. Furthermore, the reproducible IFI-GEC detection was completed within 10 min and the LOD was as low as 40 ng for lysozyme detection. All results indicated the potential of the IFI-GEC device for online and portable detection of proteins without staining.

Advances in radiative capture studies at LUNA with a segmented BGO detector

Studies of charged-particle reactions for low-energy nuclear astrophysics require high sensitivity, which can be achieved by means of detection setups with high efficiency and low backgrounds, to obtain precise measurements in the energy region of interest for stellar scenarios. High-efficiency total absorption spectroscopy is an established and powerful tool for studying radiative capture reactions, particularly if combined with the cosmic background reduction by several orders of magnitude obtained at the Laboratory for Underground Nuclear Astrophysics (LUNA). We present recent improvements in the detection setup with the Bismuth Germanium Oxide (BGO) detector at LUNA, aiming to reduce high-energy backgrounds and increase the summing detection efficiency. The new design results in enhanced sensitivity of the BGO setup, as we demonstrate and discuss in the context of the first direct measurement of the 65 keV resonance (E x = 5672 keV) of the 17O(p,γ)18F reaction. Moreover, we show two applications of the BGO detector, which exploit its segmentation. In the case of complex γ-ray cascades, e.g. the de-excitation of E x = 5672 keV in 18F, the BGO segmentation allows to identify and suppress the beam-induced background signals that mimic the sum peak of interest. We demonstrate another new application for such a detector in form of in situ activation measurements of a reaction with β + unstable product nuclei, e.g. the 14N(p,γ)15O reaction.

The new INFN-CHNet neutron imaging facility

In this paper, NICHE (Neutron Imaging for Cultural HEritage), the new neutron imaging facility of the Italian National Institute of Nuclear Physics (INFN) is shortly presented. We report on the main features of the beamline, the specifications of the detection set-up, and the performances of the imaging system. NICHE is installed at the TRIGA reactor of LENA (Laboratorio Energia Nucleare Applicata) Pavia University laboratory (Italy). The imaging facility was designed during 2020, installed in the spring 2021, and has been in operation since May 2021. NICHE is the first Italian neutron imaging station open to national external users through the INFN-CHNet network application system. NICHE allows users to obtain neutron radiographies and tomographies, thus allowing for morphological characterisation of samples. First results to highlight the potential of the facility are reported. In particular, we show the first results about spatial resolution measurement and 3D reconstruction to provide morphological analysis capabilities.

A Demonstrator for Threat Detection in Volumetric CT Scans

The detection of threat items and prohibited items inside closed containers is an active field of research and an even more important real-world application. While conventional systems use X-ray projections for inspection, they lack true three-dimensional information which is crucial for a reliable detection. In this work, we introduce a demonstrator setup for three-dimensional threat detection within a 3D printed miniature container. We created a data processing pipeline that automatically integrates CT scanning, volumetric reconstruction and the actual detection of threat objects by means of a neural network. The achieved results are very promising and could be obtained using very few annotated training samples which is a realistic assumption in this application.

Educational high school physics demonstration apparatus for acoustic landmine simulant resonance detection

This landmine “simulant” resonance detection demo was created in conjunction with a high school physics mentorship, using a variety of easily-accessibleequipment in order to demonstrate an important application of fundamental concepts of sound and vibration. A plastic tray (4 in. deep) contained a 3-in. diameter drum-like circular landmine simulant (1.5 in. high) with a thin acrylic top plate buried (1 in. deep) in a 3 in. layer of dry sifted masonry sand. A small accelerometer was place on the surface over the simulant. Airborne sound, a loud speaker chirp, with frequency slowly increasing over time, was created using a Mathematica® generated wav file played by the Raspberry Pi® computer. Sound excited the sand vibration that coupled to the top plate. The accelerometer generated a frequency response voltage, related to the sweep time. The Raspberry Pi® also played a role in implementing the A to D conversion, so that the frequency response near resonance was displayed as a voltage in a readable format. With this demo apparatus high school students will be excited by the fundamentals of wave propagation and concepts about resonance with regards to its real-life applications. [Specially inspired by James M. Sabatier’s research on acoustic landmine detection.]

Determination of absolute Np L x-ray emission intensities from 241Am decay using a metallic magnetic calorimeter

Photon emission intensities of radionuclides, i.e. the number of emitted photons per decay, are the single most important decay data when the photon spectrometry technique is employed in ionizing radiation metrology. However, their precise measurement is problematic because they are usually determined by photon spectrometry with spectrometers having a detection efficiency calibrated with x-ray and γ-ray emission intensities from other radionuclides. Therefore, these intensities are ultimately interdependent and correlated to some extent. A novel method was applied to determine the photon intensities of α-emitting radionuclides by measuring the ratio between the rate of photons in the full energy peaks and the rate of detected α-particles with the same detection set-up. Thus, there is no need to calibrate the detection efficiency and to standardize calibration sources by primary methods. The main condition to reach low uncertainties is to have a spectrometer with an intrinsic detection efficiency close to unity for the measured photons and α-particles. This condition was fulfilled by a metallic magnetic calorimeter (MMC) with an intrinsic efficiency of around 99% between 5 keV and 25 keV. In addition, the MMC provides an ultra-high energy resolution of 28 eV (full width at half maximum), facilitating the processing of the spectrum. The method was applied to determine L x-ray emission intensities from the decay of 241Am(α) → 237Np emitted between 11.9 keV and 22.4 keV. A total L x-ray emission intensity of 37.90 (12) per 100 disintegrations was obtained; the value agrees well with previous measurements and has a lower uncertainty. The uncertainties of the L x-ray groups Lα, Lηβ and Lγ were improved by a factor of two. Moreover, due to the high-energy resolution of 28 eV, a detailed set of 33 L x-ray emission intensities are provided.

Dual-panel polyvinyl toluene scintillator application as a radiation portal monitor device for gamma and neutron detection

Detection techniques for radiation portal monitors (RPMs) are being developed at Canadian Nuclear Laboratories. One of the purposes of RPM systems at the border ports of entry is to detect illegal transportation of special nuclear material (SNM), which can be used for radiation dispersal devices or nuclear weapons production.One of the most widely used detection technologies considered for RPMs is the polyvinyl toluene (PVT) scintillator. PVT is the most widely used material due to its low cost and its capability to be formed into different shapes and sizes. However, the primary limitation of PVT scintillators is their poor energy spectrum resolution, which limits the discrimination between neutron and gamma radiation.In the present work, a method that allows for the discrimination of fast neutron events from gamma events in a PVT-based RPM was investigated. This method uses two sets of plastic scintillators separated by an air gap. The gap increases the travel distances between scattering events to more easily distinguish pulses produced by neutron interactions in the scintillator from those produced by gamma rays. The time-of-flight (TOF) values between the coincident events in these two sets of scintillators were measured. The TOF for neutrons is significantly longer than the TOF for gamma rays. Another distinguishing characteristic of neutrons is that the flight time between these two scintillator panels will vary according to their energy.The results show that TOF measurements can distinguish neutron sources with sufficiently different energies. Therefore, this method is capable of identifying radioactive material based on neutron energy.In addition to the experimental work, Monte Carlo simulations were carried out using MCNP6.2. The simulation showed that the detector setup had an efficiency (which is the ratio of the number of counts recorded by the detector to the number of neutrons that are incident on the detector) of approximately 12%. Also, the MCNP results showed that the thickness of the second panel had a minimal effect on the signal and no effect on the gamma/neutron peak separation, and therefore could be any conveniently available thickness. However, increasing the air gap between panels increased the peak separation distance but reduced the signal, with a gap distance between 50 cm and 100 cm producing acceptable results.

Measurement of remanent magnetic moment using a torsion pendulum with single frequency modulation method

In TianQin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment m r of 1.1 kg dummy copper test mass, and the measurement result is (6.45±0.04(stat)±0.07(syst)) × 10−8 A⋅m2. The measurement precision of the m r is about 0.9 nA⋅m2, well below the present measurement requirement of TianQin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.

Comparison of Two Methods for SARS-CoV-2 Detection in Wastewater: A Case Study from Sofia, Bulgaria

Wastewater surveillance for monitoring the spread of SARS-CoV-2 remains important even in the current endemic stage of the COVID-19 outbreak. This approach has already demonstrated its value by providing early warnings of coronavirus spread in different communities. The aim of the present publication is to share relevant experience from the Center of Competence “Clean&Circle”, obtained in the development of an effective strategy for SARS-CoV-2 detection in the wastewater of Sofia, Bulgaria. Using four different RNA concentration/extraction methods, we revealed that the key hindering factor for successful viral detection was the presence of PCR inhibitors in the wastewater. The most efficient way to overcome their presence turned out to be the application of a specialized polymerase in the RT-PCR detection setup. Our data showed that using such an enzyme increases the detection efficiency from 1.9% to 70.5% in samples with a spiked control virus. We also evaluated the recovery rates of viral particles by using silica columns (71%), PEG precipitation (23%), ultrafiltration (15%), and MCE filtration (10%). These results support the international effort to unify and standardize the various techniques used for SARS-CoV-2 monitoring in wastewater.

Gas recirculation systems for RPC detectors: From LHC experiments to laboratory set-ups

The Resistive Plate Chamber (RPC) detectors are extensively used worldwide and at CERN LHC experiments thanks to their excellent time resolution and low cost. RPCs are often operated with a humidified gas mixture made of C2H2F4, SF6 and i-C4H10. Unfortunately, C2H2F4 and SF6 are greenhouse gases (GHGs) with a global warming potential (GWP) of 1430 and 22800 respectively and they are subject to a phase-down policy in Europe (EU F-gas regulation). It is therefore foreseeable that F-gases availability would be uncertain for the future and their price could raise possibly making gas detectors operation very costly. The reduction of GHG emissions is an objective of paramount importance for CERN and four different strategies have been identified to achieve it. One of these strategies is based on the use of gas recirculation systems. This solution is already implemented in all gas systems supplying gaseous mixtures to the CERN LHC detectors. These recirculation systems are complex and sophisticated apparatus for big detector volumes (tens to hundreds of m3) that extend from surface to underground cavern and they are controlled through an industrial Programmable Logic Controller (PLC). Their cost is considerable and therefore they are used for large detector apparatus. In order to cope with the increase of small experiments and detector facilities, the CERN gas team has developed two new portable gas recirculation systems at affordable cost. The first gas recirculation unit can be used for several detectors connected in series or parallel flushed with hundreds of liters per hour. It is controlled though a small PLC and it can regulate detector pressure at the level of the mbar. Some of these gas recirculation systems are already in use since several years at CERN GIF++ facility for CSC, GEM and RPC detectors. A second gas recirculation unit has been developed for laboratory purpose where one or two detectors are flushed with few liters per hour. In this case, the unit has to be very cheap and user-friendly in order to allow an easy operation from the final user. Both portable gas recirculation systems can be easily adapted for the different types of detector systems and set-ups thanks to their low price, flexibility and user-friendly operation. An overview of the LHC, medium and small gas recirculation systems will be given in this contribution.