切伦科夫光

For over 80 years of research, the conventional description of free-electron radiation phenomena, such as Cherenkov radiation, has remained unchanged: classical three-dimensional electromagnetic waves. Interestingly, in reduced dimensionality, the properties of free-electron radiation are predicted to fundamentally change. Here, we present the first observation of Cherenkov surface waves, wherein free electrons emit narrow-bandwidth photonic quasiparticles propagating in two-dimensions. The low dimensionality and narrow bandwidth of the effect enable to identify quantized emission events through electron energy loss spectroscopy. Our results support the recent theoretical prediction that free electrons do not always emit classical light and can instead become entangled with the photons they emit. The two-dimensional Cherenkov interaction achieves quantum coupling strengths over two orders of magnitude larger than ever reported, reaching the single-electron-single-photon interaction regime for the first time with free electrons. Our findings pave the way to previously unexplored phenomena in free-electron quantum optics, facilitating bright, free-electron-based quantum emitters of heralded Fock states.

… ``Cherenkov radiation'' in their work. Presently, the names ``Cherenkov radiation'' and ``Cherenkov effect… be termed ``Vavilov± Cherenkov radiation'' or the ``Vavilov±Cherenkov effect'' in …

A moving charged particle, such as an electron, can radiate light due to the interaction between its Coulomb field and surrounding matter. This phenomenon has spawned great interest in the fields of physics, electron microscopy, optics, biology, and materials science. Since the radiation generated by the charged particles strongly depends on the surrounding matter, artificially engineered materials with exotic electromagnetic and optic properties, including metamaterials and metasurfaces, provide an unprecedented opportunity to tailor the interaction between the charged particle and matter, and ultimately enable to manipulate the radiated light. In this review, the fundamentals of Cherenkov radiation and Smith–Purcell radiation are presented. Subsequently, the recent advances in the control of Cherenkov radiation and Smith–Purcell radiation based on metamaterials and metasurfaces are summarized. Finally, the applications using these two physical phenomena, including electron‐driven photon sources and electron accelerators, are discussed in this review.

A charged particle moving through a medium emits Cherenkov radiation when its velocity exceeds the phase velocity of light in that medium. Under the influence of a strong electromagnetic field, quantum fluctuations can become polarized, imbuing the vacuum with an effective anisotropic refractive index and allowing the possibility of Cherenkov radiation from the quantum vacuum. We analyze the properties of this vacuum Cherenkov radiation in strong laser pulses and the magnetic field around a pulsar, finding regimes in which it is the dominant radiation mechanism. This radiation process may be relevant to the excess signals of high energy photons in astrophysical observations.

Charged particles moving faster than light in a medium produce Cherenkov radiation. In traditional, positive index-of-refraction materials this radiation travels forward. Metamaterials, with negative indices of refraction, flip the radiation backward. This readily separates it from the particles, providing higher flexibility in photon manipulation and is useful for particle identification and counting. Here we review recent advances in reversed Cherenkov radiation research, including the first demonstration of backward emission. We also discuss the potential for developing new types of devices, such as ones that pierce invisibility cloaks.

Cherenkov radiation of charged particles moving with superluminal velocities in transparent media is a well-studied phenomenon with a plethora of applications. Its microscopic origins can be traced to the polarization of atomic shells, characterized by time scales in the subfemtosecond range — dynamics that eludes conventional macroscopic treatment. Here we present a theoretical framework for probing the intrinsic dynamics of Cherenkov radiation, unveiling quantum features absent in classical realm and even in a fully quantum theory in momentum space. These features include a finite formation length and spreading time of the photon, the latter becoming negative nearby the Cherenkov angle, a finite flash duration tied to the size of the electron packet, along with a shift in the photon arrival time that can be either positive or negative and necessitates going beyond the far-field approximation. The calculated time scales lie in the attosecond range for the relevant parameters, thus linking this macroscopic phenomenon back to its atomic origins. Finally, we propose that by measuring the duration of the Cherenkov flash one can in principle retrieve the length of the emitting packet, deepening our understanding of quantum coherence effects in photon emission. Charged particles moving through a medium emit Cherenkov radiation, a phenomenon widely used in physics and engineering. This work develops a quantum framework revealing attosecond-scale phenomena, including a photon spreading time that can turn negative and an attosecond delay or advance in photon arrival, offering fresh insights into the quantum nature of light emission.

… Cherenkov radiation covering λ0 ≈ 500–900nm is obtained … way to achieve thresholdless Cherenkov radiation, opens up the … Cherenkov radiation (CR) is the electromagnetic radiation …

… It was Vavilov, Cherenkov's supervisor, who proposed that the detected radiation is a distinct phenomenon. His contribution in establishing the discovery of a new radiation is …

… Cherenkov radiation is discussed in this article. The developers of the theory of the Vavilov–Cherenkov … their discovery of a new mechanism of radiation when a charged particle …

The effect of dielectric boundaries on the Cherenkov radiation (CR) produced when a fast point charge moves inside or near a material is analyzed for different shapes of the sample. Calculations are offered for a charge moving near both planar and nonplanar surfaces. CR is found to be produced even when the external charge moves outside a semi-infinite medium. For charges moving near planar boundaries, the reflected radiation interferes with the direct CR, leading to oscillations in the emission probability as a function of the impact parameter relative to the interfaces. Thin-film guided modes are excited by penetrating electrons and our calculations agree reasonably well with available experiments. The bulk limit in the emission probability is recovered for charges passing by the center of cylinders or spheres of increasingly large radius. Recent experiments of energy loss of electrons passing near dielectric spheres are explained thanks to the inclusion of retardation effects in the sphere response. These effects lead to an efficient channel of radiative energy losses. Finally, the diffraction of CR in void inclusions is proposed as a tool for providing information on otherwise inaccessible buried structures.

While spatial dose conformity delivered to a target volume has been pushed to its practical limits with advanced treatment planning and delivery, investigations in novel temporal dose delivery are unfolding new mechanisms. Recent advances in ultra-high dose radiotherapy, abbreviated as FLASH, indicate the potential for reduction in healthy tissue damage while preserving tumor control. FLASH therapy relies on very high dose rate of > 40Gy/s with sub-second temporal beam modulation, taking a seemingly opposite direction from the conventional paradigm of fractionated therapy. FLASH brings unique challenges to dosimetry, beam control, and verification, as well as complexity of radiobiological effective dose through altered tissue response. In this review, we compare the dosimetric methods capable of operating under high dose rate environments. Due to excellent dose-rate independence, superior spatial (~ <1 mm) and temporal (~ns) resolution achievable with Cherenkov and scintillation-based detectors, we show that luminescent detectors have a key role to play in the development of FLASH, as the field rapidly progresses toward clinical adaptation. Additionally, we show that the unique ability of certain luminescence-based methods to provide tumor oxygenation maps in real-time with submillimeter resolution can elucidate the radiobiological mechanisms behind the FLASH effect. In particular, such techniques will be crucial for understanding the role of oxygen in mediating the FLASH effect.

Cherenkov emission induced by external beam radiation from a clinical linear accelerator (LINAC) has been shown in preclinical molecular imaging and clinical imaging. The broad spectrum Cherenkov emission should have a short wavelength infrared (SWIR, 1000–1700 nm) component, as predicted theoretically. This report is the first experimental observation of this SWIR Cherenkov emission, induced by external beam radiation. The measured spectrum of SWIR Cherenkov emission matches the theoretical prediction, with a fluence rate near 1/3 of the visible and near infrared red emissions (Vis-NIR, 400-900 nm). Imaging in water based phantoms and biological tissues indicates that there is sufficient fluence rate for radiotherapy dosimetry applications. The spatial resolution is improved approximately 5.3 times with SWIR Cherenkov emission detection versus Vis-NIR Cherenkov emission, which provides some improvement in the potential for higher resolution Cherenkov emission dosimetry and molecular sensing during clinical radiotherapy by imaging with SWIR wavelengths.

… with the Cherenkov probe were correlated with hard x-ray emission, … the Cherenkov probe were correlated with data from several other diagnostics, including electron cyclotron emission …

… Cherenkov radiation is emitted when the condition that electron velocity is larger than c=n is satisfied, it is no longer emitted … electrons contribute to Cherenkov emission by knowing the …

For relativistic Cherenkov devices, we investigate the process of high-power microwave pulse generation with its phase correlating to the sharp edge of an e-beam current pulse. Our …

Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter impart spectral changes. These changes can be quantified by diffuse spectral fitting of the signal. Thus Cherenkov emission spectroscopy is demonstrated for the first time quantitatively in vitro and qualitatively in vivo, and has potential for real-time online tracking of tissue oxygen during radiation therapy when fully characterized and developed.

… The result is an emitted Cherenkov signal that is … Cherenkov emission from tissue is not a strong function of beam energy, despite the known strong correlation between Cherenkov inten…

… for the enhancement of the Cherenkov emission, and that is … possible to boost the Cherenkov emission by several orders of … II we study the Cherenkov emission when a linear array of …

… vacuum curvature emission and Cherenkov emission and … rise to the synergetic Cherenkov-curvature emission process. We –… in the plasma, Cherenkov-curvature and …

PURPOSE Cherenkov emission (CE)-based external beam dosimetry is envisioned to involve the detection of CE directly in water with placement of a high-resolution detector out of the field, avoiding perturbations encountered with traditional dosimeters. In this work, we lay out the groundwork for its implementation in the clinic and motivate CE-based dosimeter design efforts. To that end, we examine a formalism for broad-beam in-water CE-based dosimetry of external radiotherapy beams, design and test a Monte Carlo (MC) simulation framework for the calculation of CE-to-dose conversion factors used by the formalism, and demonstrate the experimental feasibility of this method. METHODS The formalism is conceptually analogous to ionization-based dosimetry and employs CE-to-dose conversion factors, k C θ ± δ θ , including only and all CE generated within polar angles θ ± δθ on beam axis. The EGSnrc user code SPRRZnrc is modified to calculate k C θ ± δ θ , as well as CE spectral and angular distributions. The modified code is tested with monoenergetic parallel electrons on a thin water slab. Detector configurations are examined for broad 6-22 MeV electron beams from a BEAMnrc TrueBeam model, with a focus on θ ± δ θ = 90 ∘ ± 90 ∘ (4π detection), 90 ∘ ± 5 ∘ , and 42 ∘ ± 5 ∘ ( θ = 42 ∘ is the CE angle of relativistic electrons in water). We perform a relative experimental validation at 90 ∘ with electron beams, using a simple detector design with spherical optics and geometrical optics approximation of the sensitive volume, which spans the water tank. Due to transient charged particle equilibrium, broad photon beams are generally less sensitive to beam quality, depth, and angle. RESULTS For 0.1-50 MeV electrons on a thin water slab, the code outputs CE photon spectral density per unit mass (calculated from dose and k C θ ± δ θ ) and angle in agreement with theory within ±0.03% and ± 0 . 01 ∘ , respectively, corresponding to the output precision. The 42 ∘ configuration was found impractical due to detection considerations. Detection at 90 ∘ ± δ θ for small δθ exhibited beam quality dependence of the same order as well as strong superficial depth dependence. A 4π configuration ameliorates these effects. A more practical approach may employ a large numerical aperture. In comparing with literature, we find that these effects are less pronounced for broad photon beams in water, as expected. Measured relative k C 90 ∘ ± δ θ at small δθ were within 1% of simulated factors (relative to their local average) for percent-depth CE (PDC) >50%. At other depths, deviations were in accordance with signal-to-noise, known detector limitations, and approximations. It was found that the CE spectrum is beam quality and depth invariant, while for electron beams the CE angular distribution is strongly dependent on beam quality and depth. However, the uncertainty of CE and PDC measurement at 90 ∘ ± δ θ detection for small δθ due to ± 0 . 1 ∘ deviations around δθ was shown to be ≤1% and <0.1% (k = 1), respectively. The robustness to expected detector setup variations was found to result in ≤1% (k = 1) local uncertainty contribution for PDC >50%. CONCLUSIONS Based on our MC and experimental studies, we conclude that the CE-based method is promising for high-resolution, perturbation-free, three-dimensional dosimetry in water, with specific applications contingent on comprehensive detector development and characterization.

We demonstrate that, in the presence of an external magnetic field, an uncharged classical Schwarzschild black hole moving superluminally in a dielectric with permittivity ε>1 produces Cherenkov emission. This is a new physical effect: classical (nonquantum) emission of electromagnetic waves by a completely charge-neutral “particle.” The governing equations (involving general relativity, electromagnetism, and the physics of continuous media) have no external electromagnetic source—it is the distortion of the initial electromagnetic fields by the gravity of the black hole that plays the role of a superluminally moving source. The effect relies on nonzero values of both the magnetic field and the gravitational radius, as well as on the usual Cherenkov condition on the velocity, v/c>1/ε. Unlike Cherenkov emission by a point charge, the effective source in this case is spatially distributed, with emission generated along the single Cherenkov emission cone. The emitted spectrum is red dominated, with power ∝dkz/|kz| for wave numbers |kz|≤1/RG, where RG is the Schwarzschild radius. We comment on possible observability of this process during black hole–neutron star mergers. Published by the American Physical Society 2025

External radiotherapy beams have been shown to be able to emit Cherenkov radiation. Traditionally, continuous wavelength (CW) acquisition method is adopted to measure the Cherenkov emission. In this work, a time-gated-acquisition method is introduced to measure the Cherenkov emission generated by external radiation beams from linear accelerator (LINAC) in a tissue mimic phantom. The results by the gating method are compared with the results by traditional continuous wavelength acquisition method. The presented time-gated-acquisition method is shown to be an effective way to enhance the intensity of the Cherenkov emission over the ambient light. The potential application of this acquisition method is discussed.

… Cherenkov emission from a free electron in a medium. Among such are the single-particle and collective stimulated Cherenkov … for the power of the Cherenkov emission of longitudinal …

… In this study, a fundamental comparison between the Cherenkov emission and absorbed … with Cherenkov emission, it was concluded that for x-ray photons the light emission would be …

With advances in high-dose-rate (HDR) brachytherapy, the importance of quality assurance (QA) is increasing to ensure safe delivery of the treatment by measuring dose distribution and positioning the source with much closer intervals for highly active sources. However, conventional QA is time-consuming, involving the use of several different measurement tools. Here, we developed simple QA method for HDR brachytherapy based on the imaging of Cherenkov emission and evaluated its performance. Light emission from pure water irradiated by an 192Ir γ-ray source was captured using a charge-coupled device camera. Monte Carlo calculations showed that the observed light was primarily Cherenkov emissions produced by Compton-scattered electrons from the γ-rays. The uncorrected Cherenkov light distribution, which was 5% on average except near the source (within 7 mm from the centre), agreed with the dose distribution calculated using the treatment planning system. The accuracy was attributed to isotropic radiation and short-range Compton electrons. The source positional interval, as measured from the light images, was comparable to the expected intervals, yielding spatial resolution similar to that permitted by conventional film measurements. The method should be highly suitable for quick and easy QA investigations of HDR brachytherapy as it allows simultaneous measurements of dose distribution, source strength, and source position using a single image.

Bismuth germanate (BGO) was the preferred crystal for positron emission tomography (PET) scanners, but was substituted with the emergence of faster crystals. Improvements in silicon photomultipliers (SiPMs) and the use of fast high frequency readout make it possible to use the prompt Cherenkov emission in BGO in order to boost the achievable coincidence time resolution (CTR) significantly. The large fluctuations in the detected Cherenkov photon yield are causing time or amplitude walk effects in the leading edge time discrimination, which are corrected by measuring the initial signal rise time via a double threshold system. Further a classification of “fast” and “slow” timing events is shown to make best use of all the information and upgrades the CTR for most of the 511-keV events. In order to assess the practicability of this novel approach various crystal geometries and state-of-the-art SiPMs from HPK, Ketek, Broadcom, and FBK have been evaluated with the focus on the applicability in total body PET systems. For typical PET sized crystals (3 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 3 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 20 mm³) coupled to area matching 3 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 3-mm² Broadcom SiPMs a time resolution of 261 ± 8 ps full width at half maximum (FWHM) was measured when applying time walk corrections, while the CTR of individual types of events with different Cherenkov yield range from 205 to 302-ps FWHM. A further thorough discussion and prospects of TOF-PET with BGO are given, especially in view of timing event classification of all detected 511-keV events, corresponding to various time of flight kernels ranging from high to low time resolution.

Cherenkov radiation is generally believed to be threshold‐free in hyperbolic metamaterials owing to the extremely large photonic density of states in classical local framework. Although recent advances in nonlocal and quantum plasmonics extend our understanding of light‐matter interactions in metamaterials, how such effects influence Cherenkov radiation in hyperbolic metamaterials still remains unknown. Here, it is demonstrated that effects of nonlocality add a new degree of freedom to engineer Cherenkov thresholds in hyperbolic metamaterials. The interplay between finite structural dimensions and nonlocal nature of metallic electrons results in a nonzero Cherenkov threshold. Counterintuitively, such nonlocality‐induced Cherenkov threshold can be significantly smaller than the classically predicted one if the metamaterial is designed to work around the epsilon‐near‐zero frequency. This phenomenon is attributed to the excitation of longitudinal plasmon modes which are absent in classical electromagnetic framework. These findings apply to a general class of hyperbolic materials, including metallodielectric layered structures, nanorod/nanoribbon arrays, hyperbolic van der Waals crystals, etc.

New tools for quantum electrodynamics predict surprising new behavior in the Cherenkov effect and lay the groundwork for a better understanding of quantum electrodynamics at attosecond timescales.

… Often, the Cherenkov effect is associated with the blue glow of the water … In fact, traditionally, the Cherenkov effect has various … For example, the Cherenkov threshold energy in water is …

… Light is emitted via the Cherenkov effect when the speed of a charged particle, v , exceeds the speed of light, c , in the material it passes through with refractive index n : (1) β n > 1 …

… More importantly, our results indicate that a given Cherenkov angle is connected not with one, but with two particle speeds (one below and one above the light threshold). For a point …

… and used the Cherenkov effect to convert neutron-… of the Cherenkov effect requires glasses with a high index of refraction (to lower the threshold and increase the number of Cherenkov …

… The lower threshold of RCTR is the Cherenkov threshold for the medium. The upper threshold is explained by the total internal reflection. It should be noticed that the upper threshold …

… light because the Cherenkov light threshold for protons is 482 MeV, while that for the … protons was lower than the Cherenkov light thresholds, Cherenkov light was not produced except …

… gamma source with energy above the threshold of Cherenkov radiation emission in water. … energy above the effect threshold. An attempt to estimate the number of Cherenkov photons …

In this paper, different Silicon PhotoMultiplier (SiPM) sensors have been tested with charged particles to characterize the Cherenkov light produced in the sensor protection layer. A careful position scan of the SiPM response has been performed with different prototypes, confirming the large number of firing cells and proving almost full efficiency, with the SiPM filling factor essentially negligible. This study also allowed us to study the time resolution of such devices as a function of the number of firing cells, reaching values below 20 ps. These measurements provide significant insight into the capabilities of SiPM sensors in direct detection of charged particles and their potential for several applications.

… This criterion is nearly met if we choose the gas Cherenkov threshold /8th = 1/n above the … refractive index to maximize the yield of Cherenkov light. Additional criteria, which determined …

… In this work Cherenkov light spectra were determined in experiments using a commercial … of Cherenkov radiation. The authors used this method for measuring multiply labelled samples. …

… rate of emitted Cherenkov light in the presence of water, lipids, and hemoglobin was the strongest beyond 600 nm. Changes to the spectrum of Cherenkov light emitted from tissue have …

… spectral profile of Cherenkov and ambient room light were utilized to improve Cherenkov image … set up was done, where the spectrum and illuminance of the ambient light source and …

… In ordinary cases, Cherenkov radiation is a broad and continuous spectrum radiation, and the maximum radiation frequency depends on the highest response frequency of the medium […

Color vision is used throughout medicine to interpret the health and status of tissue. Ionizing radiation used in radiation therapy produces broadband white light inside tissue through the Cherenkov effect, and this light is attenuated by tissue features as it leaves the body. In this study, a novel time-gated three-channel camera was developed for the first time and was used to image color Cherenkov emission coming from patients during treatment. The spectral content was interpreted by comparison with imaging calibrated tissue phantoms. Color shades of Cherenkov emission in radiotherapy can be used to interpret tissue blood volume, oxygen saturation and major vessels within the body. A novel three-channel intensified camera capable of imaging Cherenkov emission in full color was developed, allowing for sensitivity to in vivo biological tissue information during radiotherapy.

Purpose: Humans have reported sensations of seeing light flashes during radiotherapy, even with their eyes closed. These observations have been attributed to either direct excitation of retinal pigments or generation of Cherenkov light inside the eye. Both in vivo human and ex vivo animal eye imaging was utilized to confirm light intensity and spectra to determine its origin and overall observability. Methods & Materials: A time-gated and intensified camera was used to capture light exiting the eye of a stereotactic radiosurgery patient in real-time, thereby verifying the detectability of light through the pupil. These data were compared with follow-up mechanistic imaging of ex vivo animal eyes with thin radiation beams to evaluate emission spectra and signal intensity variation with anatomical depth. Angular dependency of light emission from the eye was also measured. Results: Patient imaging showed that light generation in the eye during radiotherapy can be captured with a signal-to-noise ratio of 68. Irradiation of ex vivo eye samples confirmed that the spectrum matched that of Cherenkov emission and signal intensity was largely homogeneous throughout the entire eye, from the cornea to the retina, with a slight maximum near 10 mm depth. Observation of the signal external to the eye was possible through the pupil from 0° – 90°, with a detected emission near 2,500 photons per millisecond (during peak emission of the ON cycle of the pulsed delivery), which is over two order of magnitude higher than the visible detection threshold. Conclusions: By quantifying the spectra and magnitude of the signal, we now have direct experimental observations that Cherenkov light is generated in the eye during radiotherapy and can contribute to perceived light flashes. Furthermore, this technique can be used to further study and measure phosphenes in the radiotherapy clinic.

… To model the spectral fluence of Cherenkov radiation in a generic tissue, the lookup table of … Cherenkov light emission from these radiation sources is a suitable source for phototherapy. …

… Squares indicate the laboratory spectrum with the light background equal to that in the … When passing from this spectrum to the energy spectrum of cosmic particles, the simulation …

… spectrum of cosmic rays in the range E ∼ 1015 eV to 6×1019 eV is studied in this paper using air Cherenkov light … of cosmic rays that describe well the energy spectrum measured. …

Recent advances in engineered material technologies (e.g., photonic crystals, metamaterials, plasmonics, etc.) provide valuable tools to control Cherenkov radiation. In all these approaches, however, the particle velocity is a key parameter to affect Cherenkov radiation in the designed material, while the influence of the particle trajectory is generally negligible. Here, we report on surface Dyakonov–Cherenkov radiation, i.e. the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal. This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory, e.g. we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction. Moreover, close to the Cherenkov threshold, such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors. These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform. The surface Dyakonov–Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification, but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.

… of a velocity threshold for radiation; and the dependence of the Cherenkov cone half-angle … detectors, Cherenkov radiation is nearly always observed using a sensitive photon detector …

… crystal face, providing the Cherenkov photon arrival time and detection coordinates at the … a Cherenkov radiation-based three-dimensional (3D) position-sensitive detector consists of …

The monitoring of near-Earth space radiation has been a key component of space agencies' strategies since their inception. The changes in these radiation fluxes, part of the broader space weather environment, originate from various sources, including high-energy protons emitted in solar particle events. These protons, with energies higher than 300 MeV, are a source of damage to satellites, space station infrastructure and personnel, and also have effects that are observed in aircraft and at ground level. Increasing the number of instruments monitoring the flux of these high-energy protons is vital for the next generation of space-based infrastructure. We present the development and characterisation of a compact Cherenkov radiation detector system for use on CubeSat missions: the high-energy proton instrument, HEPI. This detector displays particle species discrimination and has an inherent energy threshold via the Cherenkov radiation emission mechanism, enabling the system to monitor baseline levels of these high-energy protons and detect surges in the flux. The design of the detector as an instrument to be implemented in a multitude of small-volume satellite missions is presented, alongside the response of HEPI to electrons, galactic cosmic ray muons and protons produced at a beam facility.

A new design uses advanced technology to produce an efficient, high-bandwidth Cherenkov detector for relativistic charged particles. The detector consists of a diamond-lathe machined ultraviolet-grade Lucite radiator, a parabolic focusing mirror, and a photodiode with an S-20 cathode. This article discusses some details of the detector design and describes preliminary measurements of its response characteristics. The data show the detector to have an overall gain of ≊76 signal electrons per incident electron and a photodiode-limited response time of ≊450 ps.

Abstract With the upgradation of detector components, such as scintillators and photodetectors, the PET-image signal-to-noise ratio of time-of-flight positron emission tomography (TOF-PET) systems has been improved, compared to those of ordinary nonTOF-PET systems. A TOF-PET with an ultrahigh time resolution, for example a coincidence time resolution (CTR) better than few tens of picoseconds, can not only improve the image quality, but also remove the image reconstruction process, significantly impacting medical imaging. Therefore, it is crucial to develop a high-time resolution PET detector. We focus on the prompt emission of Cherenkov radiation, owing to the instantaneousness of which, a high time resolution can be expected. One of the candidates for the Cherenkov radiator is lead fluoride (PbF2) due it has excellent properties, including transparency toward the ultraviolet region, high refractive index (n = 1.82), and high density (7.77 g/cm3). Moreover, it does not contain radioisotopes, unlike lutetium-based scintillators, which are commonly used in the currently available TOF-PET detectors. In this work, we experimentally investigate the timing performance of PbF2-based Cherenkov detectors, breaking down the timing performance into physical components. 3 × 3 × 5 mm3 and 9.6 × 9 . 6 × 5 mm3 PbF2 crystals are used as Cherenkov radiators; both are attached to a microchannel plate photomultiplier tube (MCP-PMT) because the single channel MCP-PMT is one of the best photodetectors in terms of the SPTR, which is 25 ps full width at half maximum (FWHM). All the surfaces, except the end surface where the MCP-PMT is connected, are wrapped in black tape to suppress the reflections of the Cherenkov photons in the crystal. The CTR is measured by placing a detector pair face-to-face, using an 22Na point source, and an oscilloscope at 20 GS/s with a set bandwidth of 4.2 GHz. A CTR of 46.9 ps FWHM, corresponding to a position resolution of 7.0 mm, is obtained, consistent with our simulation results.

… detector based on Cherenkov radiation. We consider various materials as a basis for the detector, … The resonant nature of the small metal particles allows producing Cherenkov photons …

In time-of-flight positron emission tomography (TOF-PET), the timing capabilities of the scintillation-based detector play an important role. An approach for fast timing is using the so-called metascintillators, which combine two materials leading to the synergistic blending of their favorable characteristics. An added effect for BGO-based metascintillators is taking advantage of better transportation of Cherenkov photons through UV-transparent materials such as plastic (type EJ232). To prove this, we use an optimized Coincidence Time Resolution (CTR) setup based on electronic boards with two output signals (timing and energy) and near-ultraviolet (NUV) and vacuum-ultraviolet (VUV) silicon photomultipliers (SiPMs) from Fondazione Bruno Kessler (FBK), along with different coupling materials. As a reference detector, we employed a $3\times 3\times 5$ -mm3 LYSO:Ce,Ca crystal pixel coupled with optical grease to an NUV-HD SiPM. The evaluation is based on low-threshold rise time, energy and time of arrival of event datasets. Timing results of a BGO/EJ $232\,\,3\times 3\times 15$ -mm3 metapixel show detector time resolutions (DTRs) of 159 ps for the full photopeak. We demonstrate the possibility of event discrimination using subsets with different DTR from the rise time distributions (RTDs). Finally, we present the synergistic capability of metascintillators to enhance Cherenkov photons detection when used along with VUV-sensitive SiPMs.

Machine protection systems in high power particle accelerators are crucial. They can detect, prevent, and respond to events which would otherwise cause damage and significant downtime to accelerator infrastructure. Current systems are often resource heavy and operationally expensive, reacting after an event has begun to cause damage; this leads to facilities only covering certain operational modes and setting lower limits on machine performance. Presented here is a new type of machine protection system based upon optical fibres, which would be complementary to existing systems, elevating existing performance. These fibres are laid along an accelerator beam line in lengths of ∼100 m, providing continuous coverage over this distance. When relativistic particles pass through these fibres, they generate Cherenkov radiation in the optical spectrum. This radiation propagates in both directions along the fibre and can be detected at both ends. A calibration based technique allows the location of the Cherenkov radiation source to be pinpointed to within 0.5 m with a resolution of 1 m. This measurement mechanism, from a single device, has multiple applications within an accelerator facility. These include beam loss location monitoring, RF breakdown prediction, and quench prevention. Detailed here are the application processes and results from measurements, which provide proof of concept for this device for both beam loss monitoring and RF breakdown detection. Furthermore, highlighted are the current challenges for future innovation.

… The application of alternative, more intense radiation … comparing the characteristics of Cherenkov radiation (ChR) with … Radiation detection was performed at an angle of 90 relative …

Reversed Cherenkov radiation is the exotic electromagnetic radiation that is emitted in the opposite direction of moving charged particles in a left-handed material. Reversed Cherenkov radiation has not previously been observed, mainly due to the absence of both suitable all-metal left-handed materials for beam transport and suitable couplers for extracting the reversed Cherenkov radiation signal. In this paper, we develop an all-metal metamaterial, consisting of a square waveguide loaded with complementary electric split ring resonators. We demonstrate that this metamaterial exhibits a left-handed behaviour, and we directly observe the Cherenkov radiation emitted predominantly near the opposite direction to the movement of a single sheet electron beam bunch in the experiment. These observations confirm the reversed behaviour of Cherenkov radiation. The reversed Cherenkov radiation has many possible applications, such as novel vacuum electronic devices, particle detectors, accelerators and new types of plasmonic couplers. Reversed Cherenkov radiation has not been observed due to the absence of suitable all-metal left-handed materials for beam transport and suitable couplers for extracting the signal. Here, Duanet al. develop a metamaterial to observe reversed Cherenkov radiation using real charged particles.

… , the detection of UV radiation from EASs by telescopes of the CTA [13] Cherenkov gamma-… For estimating the fraction of UV radiation in the EAS Cherenkov radiation spectrum, we can …

… In this survey we discuss the development of Ring Imaging Cherenkov (RICH) counters for particle identification. Since 1977, it has been based on the use of gaseous photosensors in …

… of the Cherenkov angle via the direct imaging of the emitted … [4] made the Cherenkov ring imaging technique a well-… therefore applies also to Cherenkov imaging devices used in …

Abstract A ring imaging Cherenkov (RICH) detector has been installed in the CLAS12 spectrometer at Jefferson Laboratory (JLab) to provide kaon identification in the momentum range between 3 GeV/c and 8 GeV/c. The detector adopts a hybrid optics solution with aerogel radiator, light planar and spherical mirrors, and highly segmented photon detectors. We report here on the design, construction, and initial performance of the RICH during the commissioning of the detector and the first physics data taking period.

The general concepts used to form images in Ring Imaging Cherenkov (RICH) counters are described and their performance properties compared. Particular attention is paid to issues associated with imaging in the time dimension, especially in Detectors of Internally Reflected Cherenkov light (DIRC).

… So saddened by the loss of Tom Ypsilantis , it was unfortunately the time at Pylos to express our gratitude for the tremendous boost he gave to the Cherenkov Ring Imaging field. …

… of ring imaging Cherenkov (RICH) and time-of-flight detectors. A modular aerogel RICH (mRICH) detector is proposed to provide PID in the momentum range from 3 to 10 GeV/c in the …

… The ring image Cherenkov (RICH) technique has evolved into a powerful experimental tool since the publication of the first, seminal paper [1]. The field is still vigorously …

… A second set of multipaneled planar mirrors directs the Cherenkov light to matching sets of … Cones of Cherenkov light are emitted and after reflection converge to sharp rings at the focal …

… Belle II spectrometer, a proximity focusing Ring Imaging Cherenkov counter with an aerogel … each will be used to read out single Cherenkov photons with high efficiency. More than …

… other experiments at the HERA storage ring. An average interaction rate of up to 40 MHz can be achieved [1]. The main function of the ring imaging Cherenkov counter (RICH) in HERA-…

… At lower momenta the track bends more and the ring image is significant,ly blurred. Here, however, the difference in Cherenkov angle between r‘s (IC’s) and IC’s (p’s)is quite large, and …

… With the introduction of Cherenkov imaging technology on the Halcyon O-ring linear … demonstrate the imaging feasibility and optimize camera placement. Approach. Imaging parameters …

We perform a new, detailed calculation of the flux and energy spectrum of Earth-emerging τ-leptons generated from the interactions of tau neutrinos and antineutrinos in the Earth. A layered model of the Earth is used to describe the variable density profile of the Earth. Different assumptions regarding the neutrino charged- and neutral-current cross sections as well as the τ-lepton energy loss models are used to quantify their contributions to the systematic uncertainty. A baseline simulation is then used to generate the optical Cherenkov signal from upward-moving extensive air showers generated by the τ-lepton decay in the atmosphere, applicable to a range of space-based instruments. We use this simulation to determine the neutrino sensitivity for E ν ≳ 10 PeV for a space-based experiment with performance similar to that for the Probe of Extreme Multi-Messenger Astrophysics (POEMMA) mission currently under study.

… neutrino detection by Cherenkov optical radiation from muons and cascades from muons and neutrinos … The prospects for creating radio muon and neutrino detector "hearing through" a …

… The IceCube neutrino detector has recently marked the start of neutrino astronomy by … detector medium and sample Cherenkov light from tracks of muons produced by muon neutrinos, …

… in conventional liquid scintillation neutrino detectors, but also … Cherenkov neutrino detector. The first approach is to use a fast, high-light-yield liquid scintillator and fast photon detectors. …

CHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with details of the implementation and deployment of the prototype. While issues during and after the deployment of the detector prevented data taking, a number of key concepts and designs were successfully demonstrated.

… inferior to the absorption length of Cherenkov radiation in highly purified water. In the case of neutrino detectors, lattice structures are more convenient, since it is possible to construct …

This talk will describe sensitivity of past, current and future water Cherenkov detectors to a burst of supernova neutrinos.

Malignant tumors rank as a leading cause of death worldwide. Accurate diagnosis and advanced treatment options are crucial to win battle against tumors. In recent years, Cherenkov luminescence (CL) has shown its technical advantages and clinical transformation potential in many important fields, particularly in tumor diagnosis and treatment, such as tumor detection in vivo, surgical navigation, radiotherapy, photodynamic therapy, and the evaluation of therapeutic effect. In this review, we summarize the advances in CL for tumor diagnosis and treatment. We first describe the physical principles of CL and discuss the imaging techniques used in tumor diagnosis, including CL imaging, CL endoscope, and CL tomography. Then we present a broad overview of the current status of surgical resection, radiotherapy, photodynamic therapy, and tumor microenvironment monitoring using CL. Finally, we shed light on the challenges and possible solutions for tumor diagnosis and therapy using CL.

… signals from depths < 15mm is reasonable for Cherenkov light, and depths < 3mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of …

… , Cherenkov excited luminescence imaging (CELI) can be achieved using a phosphor and timegated detection to isolate the luminescence signal from the Cherenkov … (pO2) imaging of …

Light scattering leads to a severe loss of axial and transverse resolution with depth into tissue, limiting accuracy and value of biomedical luminescence imaging techniques. High-resolution imaging beyond a few-millimeter depth is prohibited because diffusive transport dominates beyond a few scattering distances. In this study, light sheet imaging through scattering media is demonstrated using a radiotherapy linear accelerator to deliver well-defined thin scanned sheets of X-rays. These sheets produce Cherenkov light within the medium, which in turn excites luminescence of an optical probe across the sheet plane. This luminescence can then be imaged by an intensified camera positioned perpendicularly to the sheet plane. The precise knowledge of the light sheet position within the medium allowed efficient correction for attenuation of the signal with depth as well as spatial deconvolution of the excitation light. Together these methods allowed for the first time a high-resolution imaging of tissue-equivalent phantoms up to 3 cm thick, yielding the precise position and shape of luminescent lesions located deep in tissue without the need for non-linear image reconstruction.

Purpose: The purpose of this study was to demonstrate high resolution optical luminescence sensing, referred to as Cherenkov excited luminescence scanning imaging (CELSI), could be achieved during a standard dynamic treatment plan for a whole breast radiotherapy geometry. Methods: The treatment plan beams induce Cherenkov light within tissue, and this excitation projects through the beam trajectory across the medium, inducing luminescence where there can be molecular reporter. Broad beams generally produce higher signal but low spatial resolution, yet for dynamic plans the scanning of the multi-leaf collimator allows for a beam-narrowing strategy by recursively temporal differencing each of the Cherenkov images and associated luminescence images. Then reconstruction from each of these size-reduced beamlets defined by the differenced Cherenkov images provides a well-conditioned matrix inversion, where the spatial frequencies are limited by the higher SNR beamlets. A built-in stepwise convergence relies on stepwise beam size reduction, which is associated with a widening of the bandwidth of Cherenkov spatial frequency and resultant increase in spatial resolution. For the phantom experiments, europium nanoparticles were used as luminescent probes and embedded at depths ranging from 3mm to 8mm. An intensity modulated radiotherapy (IMRT) plan was used to test this. Results: The Cherenkov images spatially guided where the luminescence was measured from, providing high lateral resolution, and iterative reconstruction convergence showed that optimization of the initial and stopping beamlet widths could be achieved with 15mm and 4.5mm, respectively, using a luminescence imaging frame rate of 5 per second. With the IMRT breast plan, the original lateral resolution was improved 2X, i.e. 0.08–0.24mm for target depths of 3–8mm. In comparison, a dynamic wedge (DW) plan showed an inferior image fidelity, with relative contrast recovery decreasing from 0.86 to 0.79. The methodology was applied to a 3D data set to reconstruct Cherenkov excited luminescence intensity distributions showing volumetric recovery of a 0.5mm diameter object composed of 0.5μM luminescent microbeads. Conclusions: High resolution CELSI was achieved with a clinical breast external beam radiotherapy (EBRT) plan. It is anticipated that this method can allow visualization and localization for luminescence/fluorescence tagged vasculature, lymph nodes, or superficial tagged regions with most dynamic treatment plans.

… In recent years, the ability to image this emission from tissue with Cherenkov light excitation … , termed Cherenkov-Excited Luminescence Imaging (CELI) is in its ability to image values of …

Cherenkov Radiation (CR), the blue light seen in nuclear reactors is emitted by some radiopharmaceuticals. This study showed that 1) a portion of CR could be transferred in the region of the optical spectrum where biological tissues are most transparent: as a result, upon radiance amplification in the NIR window, the detection of light could occur twice deeper in tissues than during classical Cherenkov Luminescence Imaging (CLI). 2) Cherenkov-Photodynamic Therapy (CR-PDT) on cells could be achieved under conditions mimicking unlimited depth using CR embarked light source, which is unlike standard Photodynamic Therapy (PDT) where light penetration depth is limited in biological tissues. Both results are of utmost importance for simultaneous applications in tumor resection and post-resection treatment of remaining un-resected margins, thanks to a molecular construct designed to raise its light collection efficiency (i.e. CR Energy Transfer (CRET)) by conjugation with multiple CR-absorbing (water-soluble) antenna followed by intramolecular-FRET/TBET energy transfers.

BackgroundA feasibility study was done to assess the capability of digital silicon photomultipliers to measure the Cherenkov luminescence emitted by a β source. Cherenkov luminescence imaging (CLI) is possible with a charge coupled device (CCD) based technology, but a stand-alone technique for quantitative activity measurements based on Cherenkov luminescence has not yet been developed. Silicon photomultipliers (SiPMs) are photon counting devices with a fast impulse response and can potentially be used to quantify β-emitting radiotracer distributions by CLI.MethodsIn this study, a Philips digital photon counting (PDPC) silicon photomultiplier detector was evaluated for measuring Cherenkov luminescence. The PDPC detector is a matrix of avalanche photodiodes, which were read one at a time in a dark count map (DCM) measurement mode (much like a CCD). This reduces the device active area but allows the information from a single avalanche photodiode to be preserved, which is not possible with analog SiPMs. An algorithm to reject the noisiest photodiodes and to correct the measured count rate for the dark current was developed.ResultsThe results show that, in DCM mode and at (10–13) °C, the PDPC has a dynamic response to different levels of Cherenkov luminescence emitted by a β source and transmitted through an opaque medium. This suggests the potential for this approach to provide quantitative activity measurements. Interestingly, the potential use of the PDPC in DCM mode for direct imaging of Cherenkov luminescence, as a opposed to a scalar measurement device, was also apparent.ConclusionsWe showed that a PDPC tile in DCM mode is able to detect and image a β source through its Cherenkov radiation emission. The detector’s dynamic response to different levels of radiation suggests its potential quantitative capabilities, and the DCM mode allows imaging with a better spatial resolution than the conventional event-triggered mode. Finally, the same acquisition procedure and data processing could be employed also for other low light levels applications, such as bioluminescence.

Purpose The rapid expansion of radiopharmaceutical therapy (RPT) development demands scalable preclinical dosimetry methods. While PET and SPECT remain the gold standards, their low throughput and high cost limit large-cohort studies. Cherenkov luminescence imaging (CLI) offers a high-throughput alternative but suffers from depth-dependent attenuation and photon scatter that compromise quantitative accuracy. This work develops and validates a quantitative CLI methodology incorporating attenuation and scatter corrections to enable accurate preclinical dosimetry. Methods Depth-dependent attenuation was characterized using a tissue-mimicking phantom to derive calibration coefficients. Photon scatter was modeled using GEANT4-generated Cherenkov spread functions (CSFs), applied in a depth-weighted iterative Richardson–Lucy deconvolution/reconvolution framework. The method was evaluated in NU/NU mice (n = 4) bearing MC38 tumors after injection of 86Y-NM600, an isotope suitable for both PET and CLI. Liver and tumor activities were quantified at four timepoints using PET and the proposed CLI method. Voxelized Monte Carlo dosimetry was performed for both modalities. Results CLI–PET activity quantification yielded mean errors of 15.4% (liver) and 10.3% (tumor) over the first three timepoints. Tumor absorbed doses from CLI-derived synthetic PET images (3.4 ± 0.3 Gy/MBq) were statistically indistinguishable from PET-based estimates (3.2 ± 0.2 Gy/MBq, p = 0.31). Discrepancies increased at late timepoints due to low activity and background auto-luminescence. Conclusions With appropriate depth-dependent optical attenuation calibration and Monte Carlo–derived ionizing scatter correction, CLI can provide quantitative biodistribution and dosimetry estimates comparable to PET. This approach enables high-throughput, low-cost in vivo dosimetry, expanding the feasibility of large-scale preclinical RPT studies and supporting translational radiopharmaceutical development.

… algorithm for Cherenkov-excited luminescence scanned imaging (CELSI) is … of luminescent source. Coupled continuous wave (CW) diffusion equations are used to model luminescent …

… This study demonstrates remote imaging for in vivo detection of radiation-induced tumor … ink using Cherenkov-excited luminescence imaging (CELI). Micro-liter quantities of luminescent …

… to produce Cherenkov photons, to excite luminescence of … thin sheet, images of Cherenkov-excited luminescence from a … , a series of luminescence images can be taken at …

PurposeMolecular imaging techniques visualise biomarkers for both drug development and personalised medicine. In this field, Cherenkov luminescence imaging (CLI) seems to be very attractive by allowing imaging with clinical PET radiotracers with high-throughput capabilities. In this context, we developed a fast CLI method to detect tumour hypoxia with 18F-fluoromisonidazole (FMISO) for drug development purposes.MethodsColon cancer model was induced in mice by subcutaneous injection of 1 × 106 CT-26 cells. FMISO was injected, and simultaneous PET-blood oxygen level dependent (BOLD)-MRI followed by CLI were performed along with immunohistochemistry staining with pimonidazole.ResultsThere was a significant correlation between FMISO PET and CLI tumour uptakes, consistent with the BOLD-MRI mapping. Tumour-to-background ratio was significantly higher for CLI compared with PET and MRI. Immunohistochemistry confirmed tumour hypoxia. The imaging workflow with CLI was about eight times faster than the PET-MRI procedure.ConclusionCLI is a fast and relevant tool to assess tumour hypoxia. This approach could be particularly interesting for hypoxia-targeting drug development.

Cherenkov-excited luminescence scanned imaging (CELSI) is achieved with external beam radiotherapy to map out molecular luminescence intensity or lifetime in tissue. Just as in fluorescence microscopy, the choice of excitation geometry can affect the imaging time, spatial resolution and contrast recovered. In this study, the use of spatially patterned illumination was systematically studied comparing scan shapes, starting with line scan and block patterns and increasing from single beams to multiple parallel beams and then to clinically used treatment plans for radiation therapy. The image recovery was improved by a spatial-temporal modulation-demodulation method, which used the ability to capture simultaneous images of the excitation Cherenkov beam shape to deconvolve the CELSI images. Experimental studies used the multi-leaf collimator on a clinical linear accelerator (LINAC) to create the scanning patterns, and image resolution and contrast recovery were tested at different depths of tissue phantom material. As hypothesized, the smallest illumination squares achieved optimal resolution, but at the cost of lower signal and slower imaging time. Having larger excitation blocks provided superior signal but at the cost of increased radiation dose and lower resolution. Increasing the scan beams to multiple block patterns improved the performance in terms of image fidelity, lower radiation dose and faster acquisition. The spatial resolution was mostly dependent upon pixel area with an optimized side length near 38mm and a beam scan pitch of P = 0.33, and the achievable imaging depth was increased from 14mm to 18mm with sufficient resolving power for 1mm sized test objects. As a proof-of-concept, in-vivo tumor mouse imaging was performed to show 3D rendering and quantification of tissue pO2 with values of 5.6mmHg in a tumor and 77mmHg in normal tissue.

… In this study, imaging of surface dosimetry with Cherenkov emission and scintillation dosimeters was … Luminescence images and photographs of orange (B), purple (C), and white (D) …

Scintillation detectors with excellent timing resolution enable more precise localization of radiation sources in positron emission tomography, leading to substantial improvements in diagnostic capability for diseases such as cancer and dementia. At the extreme timing precision required for such applications at the picosecond scale, detector performance is governed by the microscopic dynamics of scintillation photons generated within the detector and their subsequent detection processes. However, detector signals have conventionally been treated only as collective responses of many photons due to structural constraints inherent to photodetectors. In this study, we overcome this fundamental limitation using deep learning, enabling direct access to the timing information of individual photons. The proposed method estimates photon-by-photon arrival times directly from detector waveforms without requiring any modification to the detector structure; the method operates on an event-by-event basis without ground-truth labels by integrating an unsupervised learning framework with a physically informed detector-response model. Through comprehensive validation combining Monte Carlo simulation and experimental measurements across various detector configurations, we experimentally demonstrate improved timing resolution, visualized depth-of-interaction-dependent photon transport, and classified Cherenkov and scintillation photons based on the estimated photon-level timing information using a unified deep learning-based framework. These results provide experimental access to photon dynamics, bridging the gap between theoretical modeling and experimental observation, and they open a new data-driven pathway for discovery in detector physics and optimization.

Cherenkov imaging enables real-time visualization of megavoltage X-ray or electron beam delivery to the patient during Radiation Therapy (RT). Bio-morphological features, such as vasculature, seen in these images are patient-specific signatures that can be used for verification of positioning and motion management that are essential to precise RT treatment. However until now, no concerted analysis of this biological feature-based tracking was utilized because of the slow speed and accuracy of conventional image processing for feature segmentation. This study demonstrated the first deep learning framework for such an application, achieving video frame rate processing. To address the challenge of limited annotation of these features in Cherenkov images, a transfer learning strategy was applied. A fundus photography dataset including 20,529 patch retina images with ground-truth vessel annotation was used to pre-train a ResNet segmentation framework. Subsequently, a small Cherenkov dataset (1,483 images from 212 treatment fractions of 19 breast cancer patients) with known annotated vasculature masks was used to fine-tune the model for accurate segmentation prediction. This deep learning framework achieved consistent and rapid segmentation of Cherenkov-imaged bio-morphological features on another 19 patients, including subcutaneous veins, scars, and pigmented skin. Average segmentation by the model achieved Dice score of 0.85 and required less than 0.7 milliseconds processing time per instance. The model demonstrated outstanding consistency against input image variances and speed compared to conventional manual segmentation methods, laying the foundation for online segmentation in real-time monitoring in a prospective setting.

Cherenkov gamma telescope observes high energy gamma rays, taking advantage of the radiation emitted by charged particles produced inside the electromagnetic showers initiated by the gammas, and developing in the atmosphere. The detector records and allows for the reconstruction of the shower parameters. The reconstruction of the parameter values was achieved using a Monte Carlo simulation algorithm called CORSIKA. The present study developed multiple machine-learning-based classification models and evaluated their performance. Different data transformation and feature extraction techniques were applied to the dataset to assess the impact on two separate performance metrics. The results of the proposed application reveal that the different data transformations did not significantly impact (p = 0.3165) the performance of the models. A pairwise comparison indicates that the performance from each transformed data was not significantly different from the performance of the raw data. Additionally, the SVM algorithm produced the highest performance score on the standardized dataset. In conclusion, this study suggests that high-energy gamma particles can be predicted with sufficient accuracy using SVM on a standardized dataset than the other algorithms with the various data transformations.

The IceCube South Pole Neutrino Observatory is a Cherenkov detector instrumented in a cubic kilometer of ice at the South Pole. IceCube's primary scientific goal is the detection of TeV neutrino emissions from astrophysical sources. At the lower center of the IceCube array, there is a subdetector called DeepCore, which has a denser configuration that makes it possible to lower the energy threshold of IceCube and observe GeV-scale neutrinos, opening the window to atmospheric neutrino oscillations studies. Advances in physics sensitivity have recently been achieved by employing Convolutional Neural Networks to reconstruct neutrino interactions in the DeepCore detector. In this contribution, the recent IceCube result from the atmospheric muon neutrino disappearance analysis using the CNN-reconstructed neutrino sample is presented and compared to the existing worldwide measurements.

New deep learning techniques present promising new analysis methods for Imaging Atmospheric Cherenkov Telescopes (IACTs) such as the upcoming Cherenkov Telescope Array (CTA). In particular, the use of Convolutional Neural Networks (CNNs) could provide a direct event classification method that uses the entire information contained within the Cherenkov shower image, bypassing the need to Hillas parameterise the image and allowing fast processing of the data. Existing work in this field has utilised images of the integrated charge from IACT camera photomultipliers, however the majority of current and upcoming generation IACT cameras have the capacity to read out the entire photosensor waveform following a trigger. As the arrival times of Cherenkov photons from Extensive Air Showers (EAS) at the camera plane are dependent upon the altitude of their emission and the impact distance from the telescope, these waveforms contain information potentially useful for IACT event classification. In this test-of-concept simulation study, we investigate the potential for using these camera pixel waveforms with new deep learning techniques as a background rejection method, against both proton and electron induced EAS. We find that a means of utilising their information is to create a set Preprint submitted to Astroparticle Physics March 11, 2021 ar X iv :2 10 3. 06 05 4v 1 [ as tr oph .I M ] 1 0 M ar 2 02 1 of seven additional 2-dimensional pixel maps of waveform parameters, to be fed into the machine learning algorithm along with the integrated charge image. Whilst we ultimately find that the only classification power against electrons is based upon event direction, methods based upon timing information appear to out-perform similar charge based methods for gamma/hadron separation. We also review existing methods of event classifications using a combination of deep learning and timing information in other astroparticle physics experiments.

A fast simulation of the detector response is a vital task in high-energy physics (HEP). Traditional Monte-Carlo methods form the backbone of modern particle physics simulation software but are computationally expensive. We present a machine-learning-based approach to fast simulation of the Focusing Aerogel Ring Imaging Cherenkov (FARICH) detector response. Given a particle track and momentum, the goal is to generate realistic samples of photon hits on the detector matrix. We propose a conditional Generative Adversarial Network (cGAN) with a lightweight convolutional architecture that reproduces the projected detector response conditioned on particle parameters. We compare the cGAN against a linear statistical baseline using metrics applied to probability maps and to the reconstructed velocity distributions. The cGAN produces realistic samples and provides a significant speed-up over Monte-Carlo simulation.

Modern machine learning techniques have become increasingly important in particle physics because of their powerful pattern-recognition capabilities, including in real-time data acquisition where stringent runtime constraints apply. This paper details the performance of deep-learning-based trigger algorithms for a large water Cherenkov detector such as Hyper-Kamiokande aimed at low-energy neutrino events (below 7 MeV). The performance of custom neural-network supervised classifiers is shown alongside two anomaly-detection approaches trained solely on detector noise: a pure autoencoder and an energy-based model based on Manifold Projection--Diffusion Recovery (MPDR). The supervised model shows signal identification efficiencies of 76.7% for single electrons of 3 MeV kinetic energy, significantly exceeding signal efficiencies obtained from a traditional hit-count-based trigger of 26.4%, as does the MPDR approach with 31.8%. Runtime evaluations on GPU yield per-window inference latencies well below the millisecond scale, indicating that real-time operation is feasible.

Large-scale homogeneous detectors with optical readouts are widely used in particle detection, with Cherenkov and scintillator neutrino detectors as prominent examples. Analyses in experimental physics rely on high-fidelity simulators to translate sensor-level information into physical quantities of interest. This task critically depends on accurate calibration, which aligns simulation behavior with real detector data, and on tracking, which infers particle properties from optical signals. We present the first end-to-end differentiable optical particle detector simulator, enabling simultaneous calibration and reconstruction through gradient-based optimization. Our approach unifies simulation, calibration, and tracking, which are traditionally treated as separate problems, within a single differentiable framework. We demonstrate that it achieves smooth and physically meaningful gradients across all key stages of light generation, propagation, and detection while maintaining computational efficiency. We show that gradient-based calibration and reconstruction greatly simplify existing analysis pipelines while matching or surpassing the performance of conventional non-differentiable methods in both accuracy and speed. Moreover, the framework's modularity allows straightforward adaptation to diverse detector geometries and target materials, providing a flexible foundation for experiment design and optimization. The results demonstrate the readiness of this technique for adoption in current and future optical detector experiments, establishing a new paradigm for simulation and reconstruction in particle physics.

Matter-antimatter asymmetry is one of the major unsolved problems in physics that can be probed through precision measurements of charge-parity symmetry violation at current and next-generation neutrino oscillation experiments. In this work, we demonstrate the capability of variational autoencoders and normalizing flows to approximate the generative distribution of simulated data for water Cherenkov detectors commonly used in these experiments. We study the performance of these methods and their applicability for semi-supervised learning and synthetic data generation.