The probability to detect a twisted photon produced by a cold relativistic particle bunch of charged particles is derived. The radiation of twisted photons by such particle bunches in stationary ...electromagnetic fields and in propagating electromagnetic waves is investigated. Several general properties of both incoherent and coherent contributions to the radiation probability of twisted photons are established. It is shown that the incoherent radiation by bunches of particles traversing normally an isotropic dispersive medium (the edge, transition, and Vavilov–Cherenkov radiations) and by bunches moving in a helical undulator does not depend on the azimuthal distribution of particles in the bunch and is the same as for round bunches. As for planar undulators, the incoherent radiation by particle bunches is the same as for the bunches symmetric under reflection with respect to the axis of a twisted photon detector. At high energies of detected twisted photons, this property is universal and holds for the forward incoherent radiation by any cold relativistic particle bunch. The coherent radiation of twisted photons by such particle bunches obeys the property that we call the addition rule. This rule provides a simple means to describe the properties of coherent radiation of twisted photons. Furthermore, the strong addition rule is established for the coherent radiation by sufficiently long helical bunches. The use of this rule allows one to elaborate superradiant pure sources of twisted photons. The coherent radiation by helical bunches is considered for the edge, transition, and Vavilov–Cherenkov processes and for particles moving in undulators and plane laser waves with circular polarization. In these cases, the sum rules are deduced for the total probability to detect a twisted photon and for the projection of the total angular momentum per photon. The explicit expressions for both incoherent and coherent interference factors are derived for several simple bunch profiles.
•Radiation of twisted photons by cold relativistic beams is studied.•Coherent and incoherent contributions are investigated.•General sum rules are established.•Addition rules for radiation from helically microbunched beams are established.•Superradiant pure sources of twisted photons are investigated.
According to quantum electrodynamics, in a strong magnetic field that is constant and spatially uniform, the vacuum becomes polarized with a refractive index greater than unity. As a result, ...ultra-relativistic charged particles travelling in such media can emit Cherenkov radiation with a power spectrum directly proportional to the photon frequency ω. Therefore, by extrapolating ω beyond the critical synchrotron frequency ωc, the Cherenkov radiation will eventually dominate over its synchrotron counterpart. However, such an extrapolation is not possible. We show that in the framework of effective field theory, the maximal attainable photon frequency ωmax is about four order of magnitude less than ωc. At ω=ωmax, given the γe-factor of an electron travelling normal to a constant and spatially uniform magnetic field B, the spectrum of Cherenkov radiation becomes dominant when γe(|B|/Gauss)≳4.32×1019. Nevertheless, detecting the Cherenkov radiation in astrophysical environments remains challenging since its spectral flux density is about three orders of magnitude less than the synchrotron radiation.
This work explores the screening technique of 137Cs concentration dissolved in water via the Cherenkov counting method on a Liquid Scintillation Counter Quantulus 1220. In the event of a nuclear ...emergency or the potential radioactive leakage from the power plants, the prompt detection of two long-lived fission products, 90Sr/90Y and 137Cs, is of the greatest radiological concern. Here we present an innovative, rapid, and simple LSC method for 137Cs content determination that enables quick evaluation of the radioactive contamination status of water samples without any sample pre-treatment. The novelty in the presented Cherenkov counting technique is the addition of ionic liquid 1-butyl-3-methylimidazolium salicylate in a sample vial. Its presence in the amount of ∼1 g increases efficiency up to ∼30% via a wavelength-shifting mechanism, thus reducing the detection limit of the method more than 4 times. Without the ionic liquid's addition, the method's main parameters were detection efficiency of 6.98(11)% and a detection limit of 2.6 Bq L−1 for 300 min of counting in a 20 mL sample volume. Interference with 90Sr/90Y, a radionuclide that can contribute to the Cherenkov radiation spectrum, was also investigated. The method of distinguishing individual radionuclides (137Cs and 90Sr/90Y) in the cumulative Cherenkov spectrum is presented as well.
•Rapid screening of 137Cs content in water via the Cherenkov counting was presented.•Measurements were carried out on Liquid Scintillation Counter Quantulus 1220.•1-butyl-3-methylimidazolium salicylate, BmimSal, was added to the counting vials.•1 g of ionic liquid BmimSal increased efficiency/reduced MDA more than 4 times.•90Sr/90Y can be distinguished from 137Cs in the cumulative Cherenkov spectrum.
Cherenkov radiation (CR) derived from the decay of diagnostic and therapeutic radionuclides is currently being studied by the scientific community to determine if these emissions can be harnessed for ...cancer detection and therapy. While Cherenkov luminescence imaging (CLI) has been studied in the preclinical and clinical settings, Cherenkov radiation-induced cancer therapy (CRICT) is a relatively new area of research that harnesses the emitted photons to kill cancer cells through free radical generation and DNA damage. Nanoparticles seem well suited for developing a theranostic platform that would allow researchers to visualize therapy delivery and also generate the reactive oxygen species necessary to kill cancer cells. Herein, we report the preparation of an 89Zr–TiO2–MnO2 nanocomposite that incorporates transferrin onto the nanoparticle surface to enhance cancer cell growth inhibition. The incorporation of the positron emission tomography (PET) radioisotope 89Zr (half-life: 3.3 days) allowed for the detection of the nanoparticle using PET and for the creation of Cherenkov emissions that interacted with the nanoparticle surface to generate free radicals for therapy delivery. After preparation, these systems were observed to be stable in various media and provided excellent tumor growth control after being intratumorally injected into mice bearing CT-26 tumors. These results demonstrate that a therapeutically efficient CRICT platform can be generated using commercially available and affordable materials.
Beam diagnostics are crucial for smooth accelerator operations. Many techniques rely on instrumentation in which the beam properties are significantly affected by the measurement. Novel approaches ...aim to use Cherenkov Diffraction Radiation (ChDR) for non-invasive diagnostics. Unlike regular Cherenkov Radiation, the charged particles do not have to move inside of the medium, but it is sufficient for them to move in its vicinity as long as they are faster than the speed of light in the medium. Changes to the beam properties due to ChDR measurements are consequently negligible. To examine ChDR emission under different conditions, we placed a fused silica radiator in the DESY II Test Beam. We observed increases in ChDR intensity for electron and positron momenta between 1GeVc−1 and 5GeVc−1. Additionally, we found a larger photon yield for electrons than positrons for increasing particle momenta. However, the significance of these measurements is strongly limited by the accuracy of the conversion from the measured signal to absolute photon numbers. The results suggest a need for further research into the ChDR generation by electrons and positrons and may find application in the design of future beam diagnostic devices.
We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position ...only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, (3) and it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath.
We tested this new technique with a 16 cm2 Ge light detector with thermistor readout sitting on the surface of a large TeO2 bolometer. The light collection efficiency was increased by greater than 50% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20 eV RMS that, together with increased light collection, enabled us to obtain the best α vs β∕γ discrimination ever obtained with massive TeO2 crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE.
The Cherenkov radiation induced by megavolt X-ray beams of a medical linear accelerator is highly intense in blue and ultraviolet lights. This poses a challenge for in vivo imaging, which favors ...longer wavelengths. However, using quantum dots with a large Stokes shift, we converted the Cherenkov photons to fluorescent photons in the second near-infrared (NIR-II) window. A system was designed to provide shielding for the NIR-II camera, and high quality NIR-II CELI signal was acquired. The NIR-II CELI of X-ray beams was shown at various depths, and the condition to trigger it was also studied. Animal experiments showed this technique could visualize the delivery of X-ray radiation in mice qualitatively. We concluded that CELI induced by megavolt X-ray beams in the NIR-II window possesses a great potential as a quality control tool in radiotherapy.
Using a high-intensity terahertz (THz) pulse to accelerate particles holds a promising approach for the miniaturization of particle accelerators. Here, we propose a novel THz-driven particle ...acceleration scheme, which utilizes a Cherenkov THz pulse generated by an electron bunch to accelerate particles within the bunch, without resorting to any externally driven sources. A high-intensity Cherenkov THz pulse is first generated, as a high-charge electron bunch moves through the bunch channel in a dielectric axicon and is then reflected by the lateral face of the axicon, forming a focused THz pulse in another dielectric axicon downstream, whereby part of the original electron bunch catches the THz pulse and is accelerated for a relatively large length via the inverse Cherenkov (ICR) effect. The acceleration gradient is determined by the initial bunch charge, which can be higher than 40 MV/m, as the bunch charge is greater than 10 nC. This is an all-dielectric accelerator with simplified equipment, which affords a promising option for the development of compact and even table-top accelerators.
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