The present article summarizes the results of a study of optical Cherenkov radiation (ChR) spectral properties both theoretically and experimentally. This type of radiation has a continuous spectral ...distribution which allows to use it in different fields of physics as for charged particle identification or generation of intense THz radiation. By exploiting the frequency dependency of the target permittivity it is possible to observe quasi–monochromatic radiation. A theoretical model based on a surface current approach is presented which allows to predict angular and spectral properties of ChR. In order to test the model predictions, an experiment was carried out using 855 MeV electrons and a 0.2 mm thick quartz target as radiator which could be rotated with respect to the beam axis. Quasi–monochromatic ChR was observed with a spectrometer placed at a fix observation angle, and tilting the radiator crystal offered the possibility to tune the radiation wavelength. The monochromatization effect is attributed to the frequency dependency of the quartz permittivity, and taking into account the refraction law for emitted ChR crossing the boundary between radiator target and vacuum it is possible to deduce a dispersion relation which connects ChR wavelength and outgoing photon angle - or in an alternative way ChR wavelength and target tilt angle for fixed observation angle. The dispersion relation is clearly confirmed in the experiment, and the model predictions show a satisfactory agreement with the measurements. Exploiting the ChR monochromatization mechanism might offer versatile tools which can find applications for example in beam diagnostics at modern particle accelerators.
•Cherenkov radiation model based on the polarization currents approach.•Beam divergence and beam profile measurements based on Cherenkov radiation.•Cherenkov radiation spectrum.
We present a method to separate coherent and incoherent contributions of cathodoluminescence (CL) by using a time-resolved coincidence detection scheme. For a proof-of-concept experiment, we generate ...CL by irradiating an optical multimode fiber with relativistic electrons in a transmission electron microscope. A temporal analysis of the CL reveals a large peak in coincidence counts for small time delays, also known as photon bunching. Additional measurements allow us to attribute the bunching peak to the temporal correlations of coherent CL (Cherenkov radiation) created by individual electrons. Thereby, we show that coincidence measurements can be employed to discriminate coherent from incoherent CL and to quantify their contribution to the detected CL signal. This method provides additional information for the correct interpretation of CL, which is essential for material characterization. Furthermore, it might facilitate the study of coherent electron–matter interaction.
•Method to separate coherent and incoherent cathodoluminescence.•Time-resolved coincidence detection for cathodoluminescence in transmission electron microscopy.•Temporal correlations of coherent cathodoluminescence yield strong photon bunching.
ABSTRACT We present the results and methodology of a search for neutrinos produced in the decay of charged pions created in interactions between protons and gamma-rays during the prompt emission of ...807 gamma-ray bursts (GRBs) over the entire sky. This three-year search is the first in IceCube for shower-like Cherenkov light patterns from electron, muon, and tau neutrinos correlated with GRBs. We detect five low-significance events correlated with five GRBs. These events are consistent with the background expectation from atmospheric muons and neutrinos. The results of this search in combination with those of IceCube's four years of searches for track-like Cherenkov light patterns from muon neutrinos correlated with Northern-Hemisphere GRBs produce limits that tightly constrain current models of neutrino and ultra high energy cosmic ray production in GRB fireballs.
Recent nuclear emergencies have indicated a need for fast and reliable screening techniques for the detection of one of the most hazardous fission products 137Cs. In this work fast and efficient LSC ...method was used to detect and measure the activity of 137Cs in colored water samples doped with ionic liquid 1-butyl-3-methylimidazolium salicylate, BmimSal which increases detection efficiency via wavelength-shift of Cherenkov photons. The color quench correction curve was obtained and corrected by the Cherenkov counting technique that relies on the shift of the muonic peak channel. The method described in this work is fast and simple, its accuracy is not dependent on sample activity or energies of the emitted beta spectrum. Measured 137Cs activities do not exceed a relative deviation of 30%, which is acceptable for screening purposes in case of nuclear accidents.
•Fast and efficient LSC method for 137Cs determination by Cherenkov radiation is presented•Color quench has been monitored and corrected via muonic peak channel•Ionic liquid 1-butyl-3-methylimidazolium salicylate increased detection efficiency•Quantulus 1220TMwas used for the counting of Cherenkov radiation events.•Measured 137Cs activities do not exceed limits for screening purposes in case of nuclear accidents.
A powerful new electron-ion collider (EIC) has been recommended in the 2015 Long Range Plan for Nuclear Science for probing the partonic structure inside nucleons and nuclei with unprecedented ...precision and versatility 1. EIC detectors are currently under development 2, all of which require hadron identification over a broad kinematic range. A prototype ring imaging Cherenkov detector has been developed for hadron identification in the momentum range from 3 GeV/c to 10 GeV/c. The key feature of this new detector is a compact and modular design, achieved by using aerogel as radiator and a Fresnel lens for ring focusing. In this paper, the results from a beam test of a prototype device at Fermilab are reported.
The EAS Cherenkov light array Tunka-133, with ~ 3 km2 geometric area, is taking data since 2009.The array permits a detailed study of energy spectrum and mass composition of cosmic rays in the ...energy range from 6 · 1015 to 1018 eV. We describe the methods of time and amplitude calibration of the array and the methods of EAS parameters reconstruction. We present the all-particle energy spectrum, based on 7 seasons of operation.
► Recounts what guided the development of ground based gamma ray astronomy. ► Logic of different instrumental approaches outlined. ► Power of current Cherenkov observatories compared with other ...techniques. ► SNR spectra starting to appear with detail presenting challenge for theory. ► Importance of overlap of spacecraft and IACT energy ranges in testing processes.
Most of what we know of cosmic gamma rays has come from spacecraft, but at energies above tens of GeV it has become possible to make observations with ground-based detectors of enormously greater collecting area. In recent years one such detector type, the cluster of imaging air Cherenkov telescopes, has reached a very productive state, whilst several alternative approaches have been explored, including converted solar power collectors and novel high-altitude particle shower detectors which promised to extend the energy range covered. Key examples of development from 1952 to 2011 are followed, noting the problems and discoveries that stimulated the current work, explaining the logic of the alternative approaches that were taken. The merits of the current major Cherenkov observatories and of other viable detectors are examined and compared, with examples of the astrophysical information they are beginning to provide. The detectors are still evolving, as we still do not understand the processes onto which the gamma rays provide a window. These include the acceleration of Galactic cosmic rays (in particular, the wide-band spectra of radiation from some individual supernova remnants are still hard to interpret), the highly relativistic and variable jets from active galactic nuclei, and aspects of the electrodynamics of pulsars. Larger groups of Cherenkov telescopes still offer the possibility of an increase in power of the technique for resolvable Galactic sources especially.
The use of time-of-flight (TOF) technology in positron emission tomography (PET) is expected to enhance the performance of clinical tasks such as lesion detection and disease staging. One critical ...requirement for TOF-PET is achieving lower Coincidence Time Resolution (CTR). In this manuscript, we developed a kind of multi-anode micro channel plate photomultiplier tube (MCP-PMT) specifically designed for TOF-PET applications. The direct use of Cherenkov radiator as the optical window eliminate the optical interface between the radiator and the detector, and the multi-anode structure enables a great positional resolution. Using the fast analog-to-digital converters (FADCs) technology to record the entire waveforms of the signals, the CTR measured by a pair of MCP-PMTs was analyzed offline, and the best CTR of 40.9±12.9 ps Full Width at Half Maximum (FWHM), which is equivalent to a position resolution of 6.1±1.9mm line of response (LOR) was obtained.
Old-generation photosensitizers are minimally used in current photodynamic therapy (PDT) because they absorb in the UV/blue/green region of the spectrum where biological tissues are generally highly ...absorbing. The UV/blue light of Cherenkov Radiation (CR) from nuclear disintegration of beta-emitter radionuclides shows promise as an internal light source to activate these photosensitizers within tissue. Outline of the study: 1) radionuclide choice and Cherenkov Radiation, 2) Photosensitizer choice, synthesis and radiolabeling, 3) CR-induced fluorescence, 4) Verification of ROS formation, 5) CR-induced PDT with either free eosine and free CR emitter, or with radiolabelled eosin.
Cherenkov Radiation Energy Transfer (CRET) from therapeutic radionuclides (
Y) and PET imaging radionuclides (
F,
Ga) to eosin was shown by spectrofluorimetry and in vitro, and was shown to result in a PDT process. The feasibility of CR-induced PDT (CR-PDT) was demonstrated in vitro on B16F10 murine melanoma cells mixing free eosin (λ
= 524 nm, Φ
0.67) with free CR-emitter
F-FDG under their respective intrinsic toxicity levels (0.5 mM/8 MBq) and by trapping singlet oxygen with diphenylisobenzofuran (DPBF). An eosin-DOTAGA-chelate conjugate 1 was synthesized and radiometallated with CR-emitter
Ga allowed to reach 25 % cell toxicity at 0.125 mM/2 MBq, i.e. below the toxicity threshold of each component measured on controls. Incubation time was carefully examined, especially for CR emitters, in light of its toxicity, and its CR-emitting yield expected to be 3 times as much for
Ga than
F (considering their β particle energy) per radionuclide decay, while its half-life is about twice as small.
This study showed that in complete darkness, as it is at depth in tissues, PDT could proceed relying on CR emission from radionuclides only. Interestingly, this study also repurposed PET imaging radionuclides, such as
Ga, to trigger a therapeutic event (PDT), albeit in a modest extent. Moreover, although it remains modest, such a PDT approach may be used to achieve additional tumoricidal effect to RIT treatment, where radionuclides, such as
Y, are strong CR emitters, i.e. very potent light source for photosensitizer activation.
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