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This work reviews the progression of chemical analysis via Cherenkov emissions, i.e., Cherenkov Photometry and Cherenkov Emission Spectroscopy, from its introduction in the literature up to modern developments. In presenting the history of this field, we aim to consolidate the literature, both for reference and contextualization. We present an argument aiming to untangle why this corner of research has seen little progress while so many other directly related aspects of Cherenkov research have flourished, as well as speak to the progress of the field in recent years and prospective direction in years to come.

Background The diagnostic yield of conventional gastrointestinal (GI) endoscopy for early cancers is low because it is mainly based on morphological changes of tumors. Molecular functional changes in tumors precede morphological changes. Cherenkov luminescence endoscopy (CLE) system can perform molecular imaging of GI cancers, achieving early diagnosis of cancers. However, previous CLE systems had only been able to detect Cherenkov luminescence (CL) from about one μCi nuclide at a minimum (in vivo), but the nuclide probe absorbed by the tumor of a patient was often much less than one μCi at a routinely administered dose. This study aims to construct a clinically usable high-sensitivity CLE for molecular imaging of GI cancers. Results The minimum resolvable radioactivity of the CLE reached 0.020 μCi within 300 s (in vivo), with a sensitivity at the nanocurie for the first time. The detection sensitivity of the CLE increased by up to nearly twenty-two times over the previous system. In tumor-bearing nude mice, CLE could effectively identify all tumors with 100% concordance with both histopathology and PET/CT, and the CL signals of tumors were much stronger than those of the surrounding normal tissues ( P  < 0.05). The quality of CLE imaging at 60 s was comparable to that at 300 s (signal-to-background ratio, 2.70 ± 0.48 versus 2.98 ± 0.69, P  = 0.56). Conclusions We constructed a high-sensitivity CLE that could detect radionuclides at the nanocurie radioactivity. The CLE could detect cancers accurately through rapid molecular imaging and had the potential for early diagnosis of GI cancers in clinical practice.

Different applications require different customizations of silicon photomultiplier (SiPM) technology. We present a review on the latest SiPM technologies developed at Fondazione Bruno Kessler (FBK, Trento), characterized by a peak detection efficiency in the near-UV and customized according to the needs of different applications. Original near-UV sensitive, high-density SiPMs (NUV-HD), optimized for Positron Emission Tomography (PET) application, feature peak photon detection efficiency (PDE) of 63% at 420 nm with a 35 um cell size and a dark count rate (DCR) of 100 kHz/mm2. Correlated noise probability is around 25% at a PDE of 50% at 420 nm. It provides a coincidence resolving time (CRT) of 100 ps FWHM (full width at half maximum) in the detection of 511 keV photons, when used for the readout of LYSO(Ce) scintillator (Cerium-doped lutetium-yttrium oxyorthosilicate) and down to 75 ps FWHM with LSO(Ce:Ca) scintillator (Cerium and Calcium-doped lutetium oxyorthosilicate). Starting from this technology, we developed three variants, optimized according to different sets of specifications. NUV-HD–LowCT features a 60% reduction of direct crosstalk probability, for applications such as Cherenkov telescope array (CTA). NUV-HD–Cryo was optimized for cryogenic operation and for large photosensitive areas. The reference application, in this case, is the readout of liquid, noble-gases scintillators, such as liquid Argon. Measurements at 77 K showed a remarkably low value of the DCR of a few mHz/mm2. Finally, vacuum-UV (VUV)-HD features an increased sensitivity to VUV light, aiming at direct detection of photons below 200 nm. PDE in excess of 20% at 175 nm was measured in liquid Xenon. In the paper, we discuss the specifications on the SiPM related to different types of applications, the SiPM design challenges and process optimizations, and the results from the experimental characterization of the different, NUV-sensitive technologies developed at FBK.

The interaction of light with the quantum-vacuum is predicted to give rise to some of the most fundamental and exotic processes in modern physics, which remain untested in the laboratory to date. Electron–positron pair production from a pure vacuum target, which has yet to be observed experimentally, is possibly the most iconic. The advent of ultra-intense lasers and laser accelerated GeV electron beams provide an ideal platform for the experimental realisation. Collisions of high energy γ-ray photons derived from the GeV electrons and intense laser fields result in detectable pair production rates at field strengths that approach and exceed the Schwinger limit in the centre-of-momentum frame. A detailed experiment has been designed to be implemented at the ATLAS laser at the centre of advanced laser applications. We show full calculations of the expected backgrounds and beam parameters which suggest that single pair events can be reliably generated and detected.

X-ray Cherenkov-luminescence tomography (XCLT) produces fast emission data from megavoltage (MV) x-ray scanning, in which the excitation location of molecules within tissue is reconstructed. However standard filtered backprojection (FBP) algorithms for XCLT sinogram reconstruction can suffer from insufficient data due to dose limitations, so there are limits in the reconstruction quality with some artifacts. We report a deep learning algorithm for XCLT with high image quality and improved quantitative accuracy. To directly reconstruct the distribution of emission quantum yield for x-ray Cherenkov-luminescence tomography, we proposed a three-component deep learning algorithm that includes a Swin transformer, convolution neural network, and locality module model. A data-to-image model x-ray Cherenkov-luminescence tomography is developed based on a Swin transformer, which is used to extract pixel-level prior information from the sinogram domain. Meanwhile, a convolutional neural network structure is deployed to transform the extracted pixel information from the sinogram domain to the image domain. Finally, a locality module is designed between the encoder and decoder connection structures for delivering features. Its performance was validated with simulation, physical phantom, and experiments. This approach can better deal with the limits to data than conventional FBP methods. The method was validated with numerical and physical phantom experiments, with results showing that it improved the reconstruction performance mean square error ( ), peak signal-to-noise ratio ( ), and Pearson correlation ( ) compared with the FBP algorithm. The Swin-CNN also achieved a 32.1% improvement in PSNR over the deep learning method AUTOMAP. This study shows that the three-component deep learning algorithm provides an effective reconstruction method for x-ray Cherenkov-luminescence tomography.

Purpose This study evaluates methods for removing Cherenkov radiation (CR) from plastic scintillation detectors (PSDs), focusing on constraints specific to a 0.35 T MR‐Linac system. Methods Five CR‐removal methods were examined: cross calibration, fiber alone, multiloop, collimator rotation, and couch rotation. The first three (cross calibration, fiber alone, and multiloop) were tested on a 0.35 T MR‐Linac (ViewRay Inc., USA) using the BluePhysics PSD (Blue Physics LLC, USA). These methods do not require collimator or couch rotation. The remaining two methods (collimator rotation and couch rotation) were tested on a Varian TrueBeam (Varian Medical Systems, USA) for comparison. Measurements were performed under various setup configurations, and Cherenkov radiation extraction (CRE) values were calculated to determine each method's effectiveness. Results The multiloop approach yielded a CRE of 0.7288, making it the most practical and robust for MR‐Linac constraints because it requires neither collimator nor couch rotation. The cross calibration and fiber alone methods produced CRE values of 0.7318 and 0.7569, respectively. Collimator rotation gave 0.7255, comparable to multiloop. In contrast, couch rotation resulted in 0.7489 but exhibited more variability, suggesting lower reliability. Conclusion The multiloop method emerged as the most practical and robust technique for CR removal in 0.35 T MR‐Linac systems. Its simplicity and compatibility with MR‐Linac design constraints make it a highly effective approach for CR removal in PSD‐based radiotherapy applications.

Measuring signatures of strong-field quantum electrodynamics (SF-QED) processes in an intense laser field is an experimental challenge: it requires detectors to be highly sensitive to single electrons and positrons in the presence of the typically very strong x-ray and γ -photon background levels. In this paper, we describe a particle detector capable of diagnosing single leptons from SF-QED interactions and discuss the background level simulations for the upcoming Experiment-320 at FACET-II (SLAC National Accelerator Laboratory). The single particle detection system described here combines pixelated scintillation LYSO screens and a Cherenkov calorimeter. We detail the performance of the system using simulations and a calibration of the Cherenkov detector at the ELBE accelerator. Single 3 GeV leptons are expected to produce approximately 537 detectable photons in a single calorimeter channel. This signal is compared to Monte-Carlo simulations of the experiment. A signal-to-noise ratio of 18 in a single Cherenkov calorimeter detector is expected and a spectral resolution of 2% is achieved using the pixelated LYSO screens.

Purpose: Unlike fluorescence imaging utilizing an external excitation source, Cherenkov emissions and Cherenkov-excited luminescence occur within a medium when irradiated with high-energy x-rays. Methods to improve the understanding of the lateral spread and axial depth distribution of these emissions are needed as an initial step to improve the overall system resolution. Methods: Monte Carlo simulations were developed to investigate the lateral spread of thin sheets of high-energy sources and compared to experimental measurements of similar sources in water. Additional simulations of a multilayer skin model were used to investigate the limits of detection using both 6- and 18-MV x-ray sources with fluorescence excitation for inclusion depths up to 1 cm. Results: Simulations comparing the lateral spread of high-energy sources show approximately 100  ×   higher optical yield from electrons than photons, although electrons showed a larger penumbra in both the simulations and experimental measurements. Cherenkov excitation has a roughly inverse wavelength squared dependence in intensity but is largely redshifted in excitation through any distance of tissue. The calculated emission spectra in tissue were convolved with a database of luminescent compounds to produce a computational ranking of potential Cherenkov-excited luminescence molecular contrast agents. Conclusions: Models of thin x-ray and electron sources were compared with experimental measurements, showing similar trends in energy and source type. Surface detection of Cherenkov-excited luminescence appears to be limited by the mean free path of the luminescence emission, where for the given simulation only 2% of the inclusion emissions reached the surface from a depth of 7 mm in a multilayer tissue model.

During the last 20 years, TeV astronomy has turned from a fledgling field, with only a handful of sources, into a fully-developed astronomy discipline, broadening our knowledge on a variety of types of TeV gamma-ray sources. This progress has been mainly achieved due to the currently operating instruments: imaging atmospheric Cherenkov telescopes, surface arrays and water Cherenkov detectors. Moreover, we are at the brink of a next generation of instruments, with a considerable leap in performance parameters. This review summarizes the current status of the TeV astronomy instrumentation, mainly focusing on the comparison of the different types of instruments and analysis challenges, as well as providing an outlook into the future installations. The capabilities and limitations of different techniques of observations of TeV gamma rays are discussed, as well as synergies to other bands and messengers.

This work examines atmospheric effects on cosmic ray counts observed by a Water‐Cherenkov detector at the Argentine Antarctic Marambio Station. We analyze the influence of ground‐level barometric pressure and geopotential height at various pressure levels on daily particle rates, finding the strongest association at 100 hPa, linked to effective muon production. This relationship persists across low and high frequencies relative to the annual wave. Using barometric pressure and 100 hPa geopotential height, we developed a multiple linear regression model to describe atmospheric variations in cosmic ray flux, adjusted by meteorological seasons. By inverting the model, we estimate 100 hPa geopotential height from surface observations and validate against ERA5 reanalysis. The model performs best in spring, with reduced precision in other seasons. Further improvements in the signal‐to‐noise ratio could enhance model performance. Even with these considerations, this approach offers a practical and cost‐effective method to track 100 hPa geopotential height variability in Antarctica through daily surface observations from Water‐Cherenkov detectors, providing an important resource for Antarctic atmospheric studies. Plain Language Summary In this study, we used a detector in Antarctica to measure cosmic rays and investigate how they relate to atmospheric changes. We observed a strong connection between cosmic ray levels and the atmospheric pressure around 15 km above the surface. Based on this, we developed a model to estimate this variable using ground‐level data. This approach potentially provides a practical and cost‐effective method for monitoring the lower stratosphere in Antarctica, a region of particular interest due to its unique and dynamic behavior, which plays a critical role in global atmospheric processes. Key Points Atmospheric effects on cosmic ray counting in Antarctica Water‐Cherenkov detector enables multidisciplinary research, studying cosmic rays in relation to space weather and atmospheric dynamics Monitoring geopotential height variability at 100 hPa using ground‐level cosmic ray data