Photon Yield Research Articles

Development of a novel compact and fast SiPM-based RICH detector for the future ALICE 3 PID system at LHC

A dedicated R&D is ongoing for the charged particle identification system of the ALICE 3 experiment proposed for the LHC Run 5 and beyond.One of the subsystems for the high-energy charged particle identification will be a Ring-Imaging Cherenkov (RICH) detector.The possibility of integrating Cherenkov-based charged particle timing measurements is currently under study.The proposed system is based on a proximity-focusing RICH configuration including an aerogel radiator separated from a SiPM array layer by an expansion gap. A thin high-refractive index window of transparent material, acting as a second Cherenkov radiator, is glued on the SiPM array to enable time-of-flight measurements of charged particles by exploiting the yield of Cherenkov photons in the thin window.We assembled a small-scale prototype instrumented with different Hamamatsu SiPM array sensors with pitches ranging from 1 to 3 mm, readout by custom boards equipped with the front-end Petiroc 2A ASICs to measure charges and times.The primary Cherenkov radiator consisted of a 2 cm thick aerogel tile, while various window materials, including SiO2 and MgF2, were used as secondary Cherenkov radiators.The prototype was successfully tested in a campaign at the CERN PS T10 beam line with pions and protons. This paper summarizes the results achieved in the 2023 test beam campaign.

Enhancing the Photon Yield of Hydroponic Lettuce Through Stage-Wise Optimization of the Daily Light Integral in an LED Plant Factory

The widespread application of LED plant factories has been hindered by the high energy consumption and low light use efficiency. Adjustment of the daily light integral (DLI) offers a promising approach to enhance the light use efficiency in hydroponic cultivation within LED plant factories. However, most LED plant factories use a constant DLI during the cultivation process, which often leads to excessive light intensity in the early growth stage and insufficient light intensity in the later stage. To address this issue, this study aimed to improve the photon yield of hydroponic lettuce by optimizing the DLI at different growth stages. A logistic growth model was employed to segment the lettuce growth process, with variable DLI levels applied to each stage. DLIs of 11.5, 14.4, and 18.0 mol m−2·d−1 were implemented at the slow growth stage, and the DLIs were adjusted to 14.4, 17.3, and 21.2 mol m−2·d−1 at the rapid growth stage. Photoperiods of 16 h·d−1 and 20 h·d−1 were used for the two growth stages, and LED lamps with white and red chips (ratio of red to blue light was 1.5) were used as the light source. The results indicated that the photoperiod had no significant impact on the shoot fresh weight and photon yield under the constant DLI conditions at the slow growth stage (12 days after transplanting). The 14.4 mol m−2·d−1 treatment resulted in the highest photon yield due to the significant increases in the light absorption and net photosynthetic rate of the leaves compared to the 11.5 mol m−2·d−1 treatment. No significant differences in the specific leaf area (SLA) and leaf light absorption were observed between the 14.4 and 18.0 mol m−2·d−1 treatments; however, the photon yield and actual photochemical efficiency (ΦPSII) significantly decreased. Compared with the DLI of 14.4 mol m−2·d−1 at the rapid growth stage (24 days after transplanting), the 17.3 mol m−2·d−1 treatment with 20 h·d−1 increased the leaf light absorption by 5%, the net photosynthetic rate by 35%, the shoot fresh weight by 25%, and the photon yield by 19%. However, the treatments with DLIs above 17.3 mol m−2·d−1 resulted in notable decreases in the photon yield, ΦPSII, and photosynthetic potential. In conclusion, it is recommended to implement a 20 h·d−1 photoperiod coupled with a DLI of 14.4 mol m−2·d−1 for the slow growth stage and 17.2 mol m−2·d−1 for the rapid growth stage of hydroponic lettuce cultivation in an LED plant factory.

PHOTON AND PHOTONEUTRON OUTPUTS SIMULATION FROM A TANTALUM CONVERTER AT THE M-30 MICROTRON

Reliable information about the outputs of bremsstrahlung photons and secondary photoneutrons from converters on electron accelerators with mandatory consideration of their technical characteristics is necessary for optimizing the process of sample irradiation and predicting the results of experimental studies. The results of modeling the de- pendence of photon and photoneutron yields and their ratios on the thickness of the tantalum converter (thickness – 0.04; 0.4; 1.0; 4.0; 10.0 mm) are presented at fixed energies of the initial electron beam – 10.0, 12.5, 14.5, 17.5, and 20 MeV. Calculations were carried out for the electron accelerator of the National Academy of Sciences of Ukraine, the M-30 microtron, taking into account its technical characteristics (electron discharge node). The GEANT4 toolkit was used for computer simulation.

Photodegradation of Polyethersulfone (PES), Polyvinylidene Fluoride (PVDF) and Polymethyl Methacrylate (PMMA) Microplastics via a Metal Organic Framework Namely ZIF-8/ZnO/C

The aim of this study was to photodegrade the Polyethersulfone (PES), Polyvinylidene fluoride (PVDF) and Polymethyl methacrylate (PMMA) microplastics using Zeolitic imidazolate framework-8/Zinc oxide/Carbon (ZIF-8/ZnO/C) nanocomposite generated under laboratory conditions. The produced nanocomposite was analysed using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photo Spectroscopy (XPS), Scanning Electron Microscope (SEM), Diffuse reflectance UV-vis spectra (DRS) and Electron Spin Resonance (ESR) analyses. The maximum PES, PVDF and PPMA photodegradation yields were 99%, 98%, and 96%, respectively, at 1 mg/l ZIF-8/ZnO/C nanocomposites (NCs) concentration, 1000 mg/l microplastics concentration, at pH = 10.0, at a temperature and photodegradation time of 40°C and 20 min, under oxic conditions at a sunlight intensity of 80 W/m<sup>2</sup> and a photon yield of 16. The XRD analysis showed the generation of ZIF-8/ZnO/C, while the FTIR analysis indicated the ZnO, C, and ZIF-8.

Searching accretion-enhanced dark matter annihilation signals in the Galactic Centre

This study reanalyzes the detection prospects of dark matter (DM) annihilation signals in the Galactic Center, focusing on velocity-dependent dynamics within a spike density near the supermassive black hole (Sgr A⋆). We investigate three annihilation processes — p-wave, resonance, and forbidden annihilation — under semi-relativistic velocities, leveraging gamma-ray data from Fermi and DAMPE telescopes. Our analysis integrates a fermionic DM model with an electroweak axion-like particle (ALP) portal, exploring annihilation into two or four photons. Employing a comprehensive six-dimensional integration, we precisely calculate DM-induced gamma-ray fluxes near Sgr A⋆, incorporating velocity and positional dependencies in the annihilation cross-section and photon yield spectra. Our findings highlight scenarios of resonance and forbidden annihilation, where the larger ALP-DM-DM coupling constant Caχχ can affect spike density, potentially yielding detectable gamma-ray line spectra within Fermi and DAMPE energy resolution. We set upper limits for Caχχ across these scenarios, offering insights into the detectability and spectral characteristics of DM annihilation signals from the Galactic Center.

Device response principles and the impact on energy resolution of epitaxial quantum dot scintillators with monolithic photodetector integration

Epitaxial quantum dot (QD) scintillator crystals with picosecond-scale timing and high light yield have been created for medical imaging, high energy physics and national security applications. Monolithic photodetector (PD) integration enables the sensing of photons generated within the waveguiding crystal and allows a wide range of scintillator-photodetector coupling geometries. Until recently, these doubly novel devices have suffered from complex, high variance responses to monoenergetic sources which significantly reduces their precision and accuracy. The principles governing the overall device response have now been discerned and embodied by an expression derived within a geometrical optics framework which considers optical properties, surface roughness and photodetector coupling geometry. Response variation due to these factors was sufficiently reduced to obtain material-related energy resolution values of 2.4% with alpha particles. These findings place energy resolution alongside luminescence timescale, photon yield, and radiation hardness as outstanding properties of these engineered materials.

Informing solar blind radioluminescence imaging through a calibrated spectrum

While direct radiation detection methods offer great insight into the origin of ionizing particles and photons, their use to locate contaminated areas or concealed radioactive sources can lead to undue exposure of personnel and equipment to ionizing radiation or the potential for contamination. These same sources induce ultraviolet (UV) optical photon fluorescence in air – a process referred to as radioluminescence – that may be imaged from low dose regions over larger attenuation lengths than ionizing radiation. However, most optical detection methods are limited to low lighting conditions to image the more abundant ultraviolet-A (UV-A) photons. To extend this capability to room light or daytime conditions, the solar blind region (Ultraviolet-C (UV–C), <280 nm) can be tapped. Though the emission yield of UV-C photons is roughly two orders of magnitude lower than that in the UV-A regime, the UV-C offers dramatic improvements in signal-to-noise ratios under bright lighting conditions due to decreased background interferences. The yield of specific UV-C lines, if present in the literature at all, varies widely, which has a large impact in modeling and analyzing standoff UV-C measurement scenarios. Thus, we have captured improved radioluminescence spectra over 250–400 nm and identified observed emission peaks in ambient air. Many of the UV-C photons produced by ionizing radiation excitation result from high-energy, molecular nitrogen Gaydon-Herman transitions which have had limited study to date for this application. Relating these findings to published UV-A yields, we estimate emissions between 0.15 and 0.19 photons/MeV over 250–280 nm. We also use a commercial corona-discharge imaging camera to demonstrate outdoor UV-C radiation mapping of alpha and gamma emitters from 50 to 75 m standoffs, respectively. The imaged “counts” are compared to optically modeled values and show the same trend over distance.

Analytical formula for signal optimization in stimulated photon-photon scattering setup with three laser pulses

We consider a setup to detect stimulated photon-photon scattering using high-power lasers. Signal photons are emitted from an overlap of the incoming intense laser pulses focused in vacuum from three sides. We derive and justify a general approximate analytical formula for the angular distribution and total yield of such signal photons in terms of the parameters of the incoming pulses, including their intensity, carrier frequencies, durations, focusing, polarizations, mutual orientation and overlap. Using the obtained formula a parametric study of the signal is carried out and optimization is performed. Published by the American Physical Society 2024

Temporal Separation of Red and Blue Photons Does Not Increase Photon Capture or Yield of Lettuce

Temporal separation of red (R) and blue (B) (alternating R/B) photons has been reported to increase leaf area, photon capture, and yield of lettuce compared with delivering both colors together (concurrent R+B). We grew three diverse lettuce cultivars (Grand Rapids, Rex, and Red Sails) under concurrent R+B photons (9/1 ratio) and alternating R/B photons (9/1 ratio) under an equal daily light integral (DLI) of either 8.6 or 23 mol⋅m−2⋅d−1. Contrary to five previous studies, we found no increase in either leaf area or fresh mass and dry mass in any of the alternating R/B photon treatments compared with concurrent R+B photons. In fact, at a DLI at 8.6 mol⋅m−2⋅d−1, alternating R/B photons decreased the dry mass of ‘Grand Rapids’ and ‘Rex’ lettuce by 38% and 17%, respectively. Two previous studies reported that photosynthetic rates increased with alternating R/B photons; however, we found that the net assimilation rate was generally decreased by alternating R/B photons. An analysis of images obtained from automated digital photography revealed that the relative expansion rate of leaves was 61% higher during intervals of pure B rather than intervals of pure R photons at the same photosynthetic photon flux density; however, this did not result in a higher leaf area compared with concurrent R+B photons. Overall, our studies do not indicate that alternating R/B photons increase lettuce leaf area or yield compared with concurrent R+B photons.

Growth physiology and chlorophyll fluorescence analysis of two moss species under different LED light qualities

This study investigated the responses of Didymodon constrictus and Hypnum plumaeforme to different light qualities emitted by light-emitting diodes (LEDs), including white light (WL), red light (RL), blue light (BL), yellow light (YL), green light (GL), and a combination of red and blue light (R1B1L). The research analyzed the fluorescence imaging, photosynthetic pigments, coloration, and growth characteristics related to antioxidant enzymes in these two moss species. The results indicated that R1B1L significantly enhanced the content of photosynthetic pigments, maximum relative electron transport rate (rETRmax), saturation light intensity (IK), and the greenness of the moss. RL improved the maximum quantum yield (Fv/Fm), the light energy efficiency of H. plumaeforme and effective quantum yield in both moss species. In contrast, BL notably increased non-photochemical quenching (NPQ), photochemical quenching (qp), and the steady-state fluorescence decrease ratio (RFD) in H. plumaeforme. The application of GL significantly increases the maximum photon yield (Fv/Fm) in D. constrictus, as well as the light energy efficiency and elongation length, resulting in a shift in the color composition of both moss species towards yellow. Among the light treatments, R1B1L had the highest induction rate and promotional effect on the growth of both moss species. These mosses absorbed GL and RL effectively, while BL played a crucial role in the dissipation of heat and electron transfer in H. plumaeforme. This research provides valuable insights for the regulation of LED light environments and the physiological adaptability of moss in artificial cultivation.

Picosecond laser-driven coded-source radiography with high resolution and contrast

The X-ray sources for Compton radiography of ICF experiments are generated by using intense picosecond lasers to irradiate wire targets. The wire diameter must be designed thin enough, for example ∼ 10 µm in many published works, to comply a high spatial resolution. This results in a low laser-target interception, which limits the photon yield. We investigated a technique of coded-source radiography based on laser-driven annular sources via Monte Carlo and PIC simulations. The annular X-ray source is formed by laser irradiating tube target in which the effect of electron recirculation plays an important role. We proved that this technique has an increased spatial resolution and contrast than that using the Gaussian source produced by wire targets. Therefore, the diameter of the backlighter target can be significantly increased to uplift laser-target interception without compromising on spatial resolution. This contributes towards a reconciliation between the spatial resolution and photon yield for Compton radiography. The results predict the possibility of improving source photon yield by several times in future experiments.

High-Power Terahertz Free Electron Laser via Tapering-Enhanced Superradiance

A superradiant FEL in the THz (3 THz) region is currently operating at Ariel University. It is based on the novel ORGAD accelerator, which is a hybrid linear RF photo-cathode 6 MeV electron gun. The hybrid term stands for its unique standing wave (SW)—traveling wave (TW) structure. The undulator generates spontaneous superradiance, which corresponds to spontaneous emission when the electron bunch duration is shorter than the radiated frequency, resulting in a much higher photon yield. However, the efficiency of this scheme is still quite low. In order to achieve higher emission (by improved efficiency), we intend to implement a new and promising radiative interaction scheme: tapering-enhanced superradiance (TES). This particular undulator design employs a tapered (amplitude) undulator in the zero-slippage condition to obtain a significantly more powerful and efficient THz radiation source. At the current stage, the scheme is designed for emission at approximately 0.5 THz. The design and start-to-end simulations demonstrate significant enhancement of superradiant energy and extraction efficiency using this method compared to a reference uniform case.

Ion acceleration from golden mylar film irradiated by visible ns pulsed laser

AbstractA Pulsed ns laser operating at 532 nm wavelength with 150 mJ pulse energy was employed to irradiate micrometric thick mylar films, from 1 to 100 μm thick, covered by 0.05 μm Au in the back face. Protons and light ions have been accelerated by the electric field developed in the non‐equilibrium plasma by the laser pulse in a vacuum at an intensity of the order of 1010 W/cm2. Time‐of‐flight technique, obtained using a Faraday cup and a fast storage oscilloscope, is employed to measure the ion velocity, energy, and yield emitted in backward and forward directions. The yield of the emitted plasma photons is also evaluated. Two ion collectors are used in opposite directions to measure the plasma radiations emitted in backward and forward directions. Data analysis is based on the Coulomb‐Boltzmann‐shifted (CBS) distribution function. The target ablation yield is evaluated in the order of 3.5 μm per laser shot.

Quantitative investigation of gamma radiation in accelerator produced ISO neutron fields

In standard monoenergetic ISO neutron fields, the neutron yield of neutron-producing reactions was measured in combination with the prompt photon yield, including photon energies up to 10 MeV, for the purpose of comparing the two yields. Separating the photons produced by the target (direct photons) from those generated by secondary neutron reactions was achieved using the time-of-flight method. Photon and neutron ambient dose equivalent values were calculated from measured spectral energy distributions. Quasi monoenergetic neutron fields are needed to systematically test the response of measuring instruments to neutron radiation. For this reason, ISO has defined a number of reference neutron radiation fields covering a wide energy range up to 19 MeV. Because neutron detectors may also be affected by photon radiation, the photon fluence in the ISO neutron fields has to be known. This work focuses on quasi monoenergetic accelerator-produced neutron fields in the energy range of 24 keV to 19 MeV.

Ion acceleration from aluminised mylar film irradiated by visible ns-pulsed laser

A ns-pulsed laser operating at 532 nm wavelength has been employed to irradiate micrometric mylar films (1–100 μm) with an attached 0.1 μm Al film on its back face. Protons and light ions have been accelerated by the electric field developed in the non-equilibrium plasma generated by the laser pulse in a vacuum at an intensity of the order of 1010 W/cm2. The Time-of-flight (TOF) technique, using a Faraday cup (ion collector) coupled to a fast storage oscilloscope, has been employed to measure the ion velocity, energy and yield. The yield of plasma-emitted photons has been also evaluated. Two ion collectors have been used in opposite directions to measure the maximum ion acceleration by the TOF data acquired in backward and forward directions and the photon yield as a function of the target thickness. The evaluation of the ion energy distribution has been based on the Coulomb-Boltzmann-Shifted (CBS) distribution function.

Characterization of Cl-doped two-dimensional (PEA)2PbBr4 perovskite single crystals for fast neutron and gamma ray detection.

In this paper, a high-quality Cl-doped two-dimensional halide perovskite (PEA)2Pb(Br0.95Cl0.05)4 crystal was prepared using a seed-induced volatile solvent method. On optimizing the Cl- doping concentration, we found that 5% Cl-doping results in (PEA)2PbBr4 with the highest optical and photon yield. Based on the Cl-doped (PEA)2PbBr4 single crystal, the response characterization of the (PEA)2Pb(Br0.95Cl0.05)4 crystal in the mixed field of neutrons and gamma rays (n/γ) has been verified. Using the time-of-flight method and the linear relationship between integral charge and neutron yield, it was proved that (PEA)2Pb(Br0.95Cl0.05)4 crystal can be used for n/γ screening. The time difference between the fast neutron released by a single nuclear reaction and the γ photon arriving at the detector was 130 ns, and the arrival time of the γ photon is earlier than that of the fast neutron. This work has a broad application prospect in the study of nuclear reaction kinetics, the monitoring of the neutron yield of fusion devices and the total energy released by nuclear reactions.

Ultrasound-Induced Cascade Amplification in a Mechanoluminescent Nanotransducer for Enhanced Sono-Optogenetic Deep Brain Stimulation.

Remote and genetically targeted neuromodulation in the deep brain is important for understanding and treatment of neurological diseases. Ultrasound-triggered mechanoluminescent technology offers a promising approach for achieving remote and genetically targeted brain modulation. However, its application has thus far been limited to shallow brain depths due to challenges related to low sonochemical reaction efficiency and restricted photon yields. Here we report a cascaded mechanoluminescent nanotransducer to achieve efficient light emission upon ultrasound stimulation. As a result, blue light was generated under ultrasound stimulation with a subsecond response latency. Leveraging the high energy transfer efficiency of focused ultrasound in brain tissue and the high sensitivity to ultrasound of these mechanoluminescent nanotransducers, we are able to show efficient photon delivery and activation of ChR2-expressing neurons in both the superficial motor cortex and deep ventral tegmental area after intracranial injection. Our liposome nanotransducers enable minimally invasive deep brain stimulation for behavioral control in animals via a flexible, mechanoluminescent sono-optogenetic system.

A newly developed and verified transport capacity of Monte Carlo photon particles in RMC

In reactor shielding designs, deep-penetration shielding issues, and direct photon heating, photon transport physics is crucial. In the Reactor Monte Carlo (RMC) code, a state-of-the-art photon transport capacity is implemented in this research. For criticality and fixed-source calculations, pure photon and coupled neutron-photon transport are now simulated for four photon-atomic interactions, including Rayleigh scattering, Compton scattering, Photoelectric effect, and Pair production, as well as three major processes of the secondary photons generation (Atomic relaxation, Electron-positron annihilation, and Bremsstrahlung by electrons and positrons). In order to properly balance energy release and deposition during neutron-induced photon production, the yield of photons by neutrons is scaled by a correction factor to account for the delayed gamma radiation, and the effective multiplication factor keff is used in an uncritical system. Using an Automatic Library Generator (ALG) code, a new database for photon transport is processed with the ENDF/B evaluated nuclear data library. Numerous cases, such as a point source in an infinite geometry, a photon beam source in a cylinder geometry, and a fuel assembly in the VERA benchmark, are verified against the Monte Carlo (MC) code OpenMC. Despite some notable differences in the comparison of the photon flux at certain energy ranges, which are caused by differences in the database and also the physics implementation, the results of the energy and spatial distributions of photon flux, and the photon heating show generally good agreement and relative errors are nearly within a triple statistical standard deviation. RMC now offers advanced photon transport capacity for reaction core and shielding applications.

Timing Estimation and Limits in TOF-PET Detectors Producing Prompt Photons.

The production of prompt photons providing high photon time densities is a promising avenue to reach ultrahigh coincidence time resolution (CTR) in time-of-flight PET. Detectors producing prompt photons are receiving high interest experimentally, ignited by past exploratory theoretical studies that have anchored some guiding principles. Here, we aim to consolidate and extend the foundations for the analytical modeling of prompt generating detectors. We extend the current models to a larger range of prompt emission kinetics where more stringent requirements on the prompt photon yield rapidly emerge as a limiting factor. Lower bound and estimator evaluations are investigated with different underlying models, notably by merging or keeping separate the prompt and scintillation photon populations. We further show the potential benefits of knowing the proportion of prompt photons within a detection set to improve the CTR by mitigating the detrimental effect of population (prompt vs scintillation) mixing. Taking into account the fluctuations on the average number of detected prompt photons in the model reveals a limited influence when prompt photons are accompanied by fast scintillation (e.g., LSO:Ce:Ca) but a more significant effect when accompanied by slower scintillation (e.g., BGO). Establishing performance characteristics and limitations of prompt generating detectors is paramount to gauging and targeting the best possible timing capabilities they can offer.

Toxicity, physiological, and morphological alterations of Indian camphorweed (Pluchea indica) in response to excess copper.

Indian camphorweed (Pluchea indica (L.) Less.) is used as herbal tea due to the presence of volatile aromatic oils and several phytochemical compounds. The aim of this study was to assess the impact of copper (Cu) contamination on the physiology and morphology of P. indica, and the health risks associated with its consumption as tea. The cuttings of P. indica were subjected to 0mM (control), 5mM (low Cu), and 20mM (excess Cu) of CuSO4 treatments for 1, 2, and 4weeks. Thereafter, Cu contamination as well as physiological and morphological parameters were assessed. Cu accumulation was higher in the root tissues of plants (25.8 folds higher as compared to the leaves) grown under 20mM CuSO4 for 4weeks. This increased Cu accumulation resulted in the inhibition of root length, root fresh weight, and root dry weight. Cu concentration was found maximum (1.36μgg-1 DW) in the leaf tissues under 20mM Cu exposure for 4weeks, with the highest target hazard quotient (THQ = 1.85), whereas Cu was not detected in control. Under exposure to 20mM Cu treatment for 4weeks, leaf greenness, maximum quantum yield of photosystem II, and photon yield of photosystem II diminished by 21.4%, 16.1%, and 22.4%, respectively, as compared to the control. Leaf temperature was increased by 2.5°C, and the crop stress index (CSI) exceeded 0.6 when exposed to 20mM Cu treatment for 2 and 4weeks; however, the control had a CSI below 0.5. This led to a reduced transpiration rate and stomatal conductance. In addition, the net photosynthetic rate was also found sensitive to Cu treatment, which resulted in decreased shoot and root growth. Based on the key results, it can be suggested that P. indica herbal tea derived from the foliage of plants grown under a 5mM Cu level (0.75μgg-1 DW) with a target hazard quotient below one aligns with the recommended dietary intake of Cu in leafy vegetables. The study recommends choosing cuttings from plants with a small canopy as plant material in the greenhouse microclimates to validate the growth performance in the Cu-contaminated soil and simulate the natural shrub architecture and life cycle.