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Abstract The global challenge of on-site detection of highly enriched uranium (HEU), a substance with considerable potential for unauthorized use in nuclear security, is a critical concern. Traditional passive nondestructive assay (NDA) techniques, such as gamma-ray spectroscopy with high-purity germanium detectors, face significant challenges in detecting HEU when it is shielded by heavy metals. Addressing this critical security need, we introduce an on-site detection method for lead-shielded HEU employing a transportable NDA system that utilizes the 252Cf rotation method with a water Cherenkov neutron detector. This cost-effective NDA system is capable of detecting 4.17 g of 235U within a 12 min measurement period using a 252Cf source of 3.7 MBq. Integrating this system into border control measures can enhance the prevention of HEU proliferation significantly and offer robust deterrence against nuclear terrorism.

The global challenge of on-site detection of highly enriched uranium (HEU), a substance with considerable potential for unauthorized use in nuclear security, is a critical concern. Traditional passive nondestructive assay (NDA) techniques, such as gamma-ray spectroscopy with high-purity germanium detectors, face significant challenges in detecting HEU when it is shielded by heavy metals. Addressing this critical security need, we introduce an on-site detection method for lead-shielded HEU employing a transportable NDA system that utilizes the 252Cf rotation method with a water Cherenkov neutron detector. This cost-effective NDA system is capable of detecting 4.17 g of 235U within a 12 min measurement period using a 252Cf source of 3.7 MBq. Integrating this system into border control measures can enhance the prevention of HEU proliferation significantly and offer robust deterrence against nuclear terrorism. [ABSTRACT FROM AUTHOR]

The JEM-EUSO program aims to study ultra-high energy cosmic rays from space. To achieve this goal, it has realized a series of experiments installed on the ground (EUSO-TA), various on stratospheric balloons (with the most recent one EUSO-SPB2), and inside the International Space Station (Mini-EUSO), in light of future missions such as K-EUSO and POEMMA. At nighttime, these instruments aim to monitor the Earth's atmosphere measuring fluorescence and Cherenkov light produced by extensive air showers generated both by very high-energy cosmic rays from outside the atmosphere and by neutrino decays. As the two light components differ in duration (order of microseconds for fluorescence light and a few nanoseconds for Cherenkov light) they each require specialized sensors and acquisition electronics. So far, the sensors used for the fluorescence camera are the Multi-Anode Photomultiplier Tubes (MAPMTs), while for the Cherenkov one, new systems based on Silicon PhotoMultipliers (SiPMs) have been developed. In this contribution, a brief review of the experiments is followed by a discussion of the tests performed on the optical sensors. Particular attention is paid to the development, test, and calibration conducted on SiPMs, also in view to optimize the geometry, mass, and weight in light of the installation of mass-critical applications such as balloon- and space-borne instrumentation. [ABSTRACT FROM AUTHOR]

The JEM-EUSO program aims to study ultra-high energy cosmic rays from space. To achieve this goal, it has realized a series of experiments installed on the ground (EUSO-TA), various on stratospheric balloons (with the most recent one EUSO-SPB2), and inside the International Space Station (Mini-EUSO), in light of future missions such as K-EUSO and POEMMA. At nighttime, these instruments aim to monitor the Earth’s atmosphere measuring fluorescence and Cherenkov light produced by extensive air showers generated both by very high-energy cosmic rays from outside the atmosphere and by neutrino decays. As the two light components differ in duration (order of microseconds for fluorescence light and a few nanoseconds for Cherenkov light) they each require specialized sensors and acquisition electronics. So far, the sensors used for the fluorescence camera are the Multi-Anode Photomultiplier Tubes (MAPMTs), while for the Cherenkov one, new systems based on Silicon PhotoMultipliers (SiPMs) have been developed. In this contribution, a brief review of the experiments is followed by a discussion of the tests performed on the optical sensors. Particular attention is paid to the development, test, and calibration conducted on SiPMs, also in view to optimize the geometry, mass, and weight in light of the installation of mass-critical applications such as balloon- and space-borne instrumentation.

Spectrum difference was used to study the dependence of Cherenkov light yields of complex and simple substances added to liquid radiators on their concentration. The radiation was generated by cosmic muons and 194-MeV positrons produced at the S-25R electron synchrotron. Dependence of the characteristics of Cherenkov radiation spectra of simple substances on their position in the periodic system of elements has been studied. Cherenkov light yields as a function of the ratio of atomic numbers Z and the volume of atoms of these substances have been estimated. Based on the results of the study, use of Cherenkov radiation is suggested as a method for determining the type of substances (Cherenkov spectrometry). [ABSTRACT FROM AUTHOR]

EUSO-TA is a ground-based fluorescence telescope built to validate the design of ultra-high energy cosmic ray fluorescence detectors to be operated in space with the technology developed within the Joint Exploratory Missions for Extreme Universe Space Observatory (JEM-EUSO) program. It operates at the Telescope Array (TA) site in Utah, USA. With an external trigger provided by the Black Rock Mesa fluorescence detectors of the Telescope Array experiment, with EUSO-TA we observed air-showers from ultra-high energy cosmic rays, as well as laser events from the Central Laser Facility at the TA site and from portable lasers like the JEM-EUSO Global Light System prototype. Since the Black Rock Mesa fluorescence detectors have a ∼ 30 times larger field of view than EUSO-TA, they allow a primary energy reconstruction based on the observation of a large part of the shower evolution, including the shower maximum, while EUSO-TA observes only a part of it, usually far away from the maximum. To estimate the detection limits of EUSO-TA in energy and distance, a method was developed to re-scale their energy, taking into account that EUSO-TA observes only a portion of the air-showers. The method was applied on simulation sets with showers with different primaries, energy, direction, and impact point on the ground, as well as taking into account the experimental environment. EUSO-TA was simulated with an internal trigger and different elevation angles and electronics. The same method was then applied also to real measurements and compared to the simulations. In addition, the method can also be used to estimate the detection limits for experiments that are operated at high altitudes and in most cases can see the maximum of the showers. This was done for EUSO-SPB1, an instrument installed on a super-pressure balloon. Finally, the expected detection rates for EUSO-TA were also assessed using the prepared simulated event sets. The rates correspond to a few detections per recording session of 30 h of observation, depending on the background level and the configuration of the detector. [ABSTRACT FROM AUTHOR]

In this study, a new type of photonic crystal (PC) designed as a transmitter. The transmittance spectra of the one-dimensional (1D) photonic crystal which are consist of silicon dioxide/magnesium fluoride (SiO2/MgF2). We are simulated the results using different incident angles, and the results showed a high transmittance (99.5%) within the wavelength range of (200–700 nm). Simulations of two-dimensional (2D) photonic crystals were studied, as well as the transmittance values were investigated. As a transmitter, photonic crystals in a one-dimensional array of SiO2 and MgF2 with periodicities N = 5 were employed around the wall of the Cherenkov counter vial. The high transmittance of the SiO2/MgF2 PC allows Cherenkov light to pass without any losing in its initial incident intensity which improves the Cherenkov counting efficiency, which is utilized in a wide range of applications. By replacing the traditional polyethylene (generally used to fabricate the walls of the counter vial) with the high transmittance photonic crystal SiO2/MgF2 which is allow to the most of the emitted Cherenkov radiation to reach the photomultiplier tube without any losing in its way to the tube. Subsequently, the efficiency of the Cherenkov counter was improved. Comparing the counting efficiency for both the polyethylene and the SiO2/MgF2 photonic crystal, it was found that the counting efficiency will be increased by 15% in one-dimension and 9.5% in two-dimensions if the polyethylene walls of the vial were replaced by SiO2/MgF2. [ABSTRACT FROM AUTHOR]

We present the results of the Hamamatsu R5912 photomultiplier tube modelling and simulating. The model can be adapted to any photomultiplier architecture by changing the number of electrodes, voltage distribution, and intrinsic PMT parameters. Our approach solves the use of tapered voltage dividers and allows photomultiplier simulations under stimulation conditions. The model implementation is not limited to SPICE-based software but also be used with compiled and interpreted programming languages. The modeled pulse charge of a vertical muon differs about 4% from the data. The resistive divider model tested reproduces the voltage distribution along the dynodes with a variance of ~3.5%. We compare the photomultiplier model linearity with the data from the operating LAGO’s (Latin American Giant Observatory) water Cherenkov detectors installed at Bucaramanga-Colombia and Bariloche-Argentina. [ABSTRACT FROM AUTHOR]

When various materials are used as radiators for Cherenkov detectors registering electron fluxes with energies of tens to hundreds of keV, cathodoluminescence negatively affects the useful signal. Therefore, in the process of creating Cherenkov detectors, the search for materials with a low level of the cathodoluminescence is important. In this paper, the spectral and amplitude-time characteristics of the yttrium sesquioxide ceramics glow under irradiation with an electron beam with electron energy up to ~ 350 keV are experimentally studied. The experimental spectrum of the ceramics glow is compared with the calculated spectrum of Cherenkov radiation. It is shown that the main part of the ceramics radiation energy belongs to Cherenkov radiation, and the cathodoluminescence level is low. The conclusion on the suitability of yttrium sesquioxide ceramics as a material for radiators of Cherenkov detectors is made. [ABSTRACT FROM AUTHOR]

Neutrino telescopes are designed to search for neutrino sources in the Universe, exploiting the Cherenkov light emitted along the path of the charged particles produced in interactions occurring close to the detector volume. Their huge size and the shield offered by large water or ice overburden make them excellent tools to search for exotic and rare particles in the cosmic radiation. In particular, they are sensitive to particles not predicted by the Standard Model that could be messenger of new physics. An overview of the experimental scenario and the relevant results obtained looking for magnetic monopoles, dark matter candidates and other exotic relic particles with neutrino telescopes is given, together with the description of possible new perspectives. [ABSTRACT FROM AUTHOR]

The ALICE High Momentum Particle IDentification (HMPID) is a Ring Imaging Cherenkov detector that identifies π, k and p in the transverse momentum interval 1 < p T < 5 GeV/ c. The HMPID consists of seven proximity focusing RICH modules, 1.3 × 1.3 m2 each. They are based on liquid C 6 F 14 as Cherenkov radiator, and on MWPCs equipped with CsI pad segmented photocathodes as photon detector. During the LHC Long Shutdown 2 (LS2, 2019–2021) the HMPID underwent upgrading activities that increased the event read out rate up to ∼20 kHz, 10 times faster than in Run 2. The performance of the read-out electronics and the MWPCs status after a stop of 4 years, using the first Run 3 data (2022), are presented. The HMPID will also constraint the measurement of the inelastic (anti-)deuteron inelastic cross section in the momentum interval 0.2–2 GeV/ c. For such aim during LS2 two aluminium absorbers 1.3 × 1.3 m2, one with a thickness of 8 cm, half interaction length, and the other with a thickness of 4 cm, were installed in front of two RICH modules. Preliminary Monte Carlo results on the expected uncertainties on the cross section measurement are given. Finally, the projection of the CsI photocathodes stability at the end of Run 3 after the absorption of a charge dose ten times higher than in Run 2, is discussed. [ABSTRACT FROM AUTHOR]

The Time Of Propagation (TOP) counter is a novel particle identification detector which relies on the precise detection time of Cherenkov photons produced by charged particles traversing a quartz bar. The TOP counter is constituted by 16 modules that cover the barrel region of the Belle II detector. Each module is instrumented with 32 Micro-Channel-Plate Photo-Multiplier-Tube (MCP-PMT) detectors, which are read out by dedicated fast waveform-sampling front-end electronics. After recalling the performance goals and stringent design requirements of the TOP counter, a comprehensive overview of its calibration strategies will be given. The status of the integration with the other Belle II sub-detectors and the performance during the commissioning phase with cosmic ray data will be presented, along with a preliminary study of the first SuperKEKB collision events. [ABSTRACT FROM AUTHOR]

A combined time projection chamber-Cherenkov (TPCC) prototype detector has been developed as part of the detector research and development program for a future electron–ion collider (EIC). The prototype was tested at the Fermilab test beam facility (FTBF) to provide a proof of the principle to demonstrate the ability to measure particle tracks and provide particle identification (PID) information within a common detector volume. The time projection chamber (TPC) portion consists of a $10 \times 10 \times 10$ cm3 field cage, which delivers charge from tracks to a quadruple gas electron multiplier (GEM) with zigzag-shaped charge collection anodes. The Cherenkov portion consists of a photosensitive quadruple GEM detector with a CsI photocathode. As tracks pass through the drift volume of the TPC, the generated Cherenkov light is able to escape through sparsely arranged wires making up one side of the field cage, facing the CsI photocathode. The Cherenkov detector is thus operated in a windowless, proximity focused configuration for high efficiency. Pure CF4 is used as the working gas for both detector components, mainly due to its transparency into the deep UV, as well as its high N0. Results from the beam test, including the position resolution as well as the particle id capabilities of the detector, are discussed in this paper. [ABSTRACT FROM AUTHOR]

A Cherenkov detector based on an array of five lead fluoride (β -PbF 2) crystals of size 30 mm × 30 mm × 160 mm read out by reverse-type avalanche photodiodes (APD's) of active area 10 mm × 10 mm was used to measure the flux of secondary particles emerging from the annihilation of pulsed beams of antiprotons at the Antiproton Decelerator of CERN. We compared the relative photon yields of radiators made of β -Pb F 2 , fused silica, UV-transparent acrylic, lead glass, and a lead-free, high-refractive-index glass. Some p-i-n photodiodes were also used for the readout, but the output signals were dominated by the nuclear counter effect (NCE) of secondary particles traversing the 300 μ m thick depletion regions of the photodiodes. Smaller NCE were observed with the APD's, as the maximum electronic gain in them occurred predominately for electron–ion pairs that were generated in the thin p -type semiconductor layer that preceded the p-n junction of high electric field where amplification took place. [ABSTRACT FROM AUTHOR]

Abstract We have developed a new threshold Cherenkov detector for online triggering in the H-dibaryon search experiment at the K1.8 beam line at J-PARC. Silica aerogel radiators with a refractive index of n = 1. 04 will cover an effective area of 550 × 220 mm 2. The Cherenkov detector will be placed in a high magnetic field between two spectrometer magnets. Three prototypes and a real-size mockup module have been tested using pions and protons from photoproduction at SPring-8. For momentum ranging from 1.0 to 1.1 GeV ∕ c , a suppression factor of 1 0 3 could be achieved for pions, with a factor of 1 0 − 2 for proton misidentification. [ABSTRACT FROM AUTHOR]

Abstract Aiming to develop a Time-of-Flight (TOF) detector with a precision down to about 50 ps (σ) in time, radiation hard and operating with a high radiation rate of relativistic heavy ions of up to 107 per spill of 1 to 10 s., we have constructed a new Time-of-Flight Cherenkov detector based on an Iodine-Naphthalene liquid radiator. This fluid with high refractive index (n=1.7003) was chosen to cover the corresponding velocities of the ions β ∼ 0.59-0.92 at the future Super-FRS at FAIR. The application of a liquid radiator allows to circulate the material and therefore greatly reduce the effects of a degradation of the optical performance during exposure to the high ion rates and radiation dose at the focal planes of the Super-FRS. The key properties of the prototype of a TOF-Cherenkov detector have been investigated in measurements with nickel ions at GSI in 2014. More recently, TOF measurements were performed with xenon ions at 600 MeV/u at GSI in 2016 and a timing resolution of 63 ps (standard deviation σ) was achieved. [ABSTRACT FROM AUTHOR]

The Belle II experiment is a high luminosity electron and positron collider experiment at SuperKEKB in Japan. The Time-Of-Propagation counter is a detector for particle identification in the barrel region. Micro-channel-plate photomultipliers are used as photodetectors and measure photon timing with a resolution of 30 ps; this leads to excellent particle identification performance. One of the issues is the photocathode lifetime of the photomultiplier tubes. Monitoring tools have been developed to measure the tube gain, accumulated output charge density and quantum efficiency during physics data taking. The gain was seen to decrease by about 10%. Although the accumulated output charge density is small compared to the tube expected lifetime, a quantum efficiency degradation was found larger than expected for 5% of the tubes after threshold efficiency calibration. Several causes for this degradation are being investigated. They can possibly be related to tube production and noise from the read-out system. [ABSTRACT FROM AUTHOR]

Dichlorodifluoromethane (R-12) has been widely used as a radiator gas in pressure threshold Cherenkov detectors for high-energy particle physics. However, that compound is becoming unavailable due to the Montreal Protocol. To find a replacement with suitably high refractive index, we use a combination of theory and experiment to examine the polarizability and refractivity of several non-ozone-depleting compounds. Our measurements show that the fourth-generation refrigerants R-1234yf (2,3,3,3-tetrafluoropropene) and R-1234ze(E) ( trans -1,3,3,3-tetrafluoropropene) have sufficient refractivity to replace R-12 in this application. If the slight flammability of these compounds is a problem, two nonflammable alternatives are R-218 (octafluoropropane), which has a high Global Warming Potential, and R-13I1 (trifluoroiodomethane), which has low Ozone Depletion Potential and Global Warming Potential but may not be sufficiently inert. [ABSTRACT FROM AUTHOR]

A slow control system (SCS) for the Aerogel Ring Imaging Cherenkov (ARICH) counter in the Belle II experiment was newly developed and coded in the development frameworks of the Belle II DAQ software. The ARICH is based on 420 Hybrid Avalanche Photo-Detectors (HAPDs). Each HAPD has 144 pixels to be readout and requires 6 power supply (PS) channels, therefore a total number of 2520 PS channels and 60,480 pixels have to be configured and controlled. Graphical User Interfaces (GUIs) with detector oriented view and device oriented view, were also implemented to ease the detector operation. The ARICH SCS is in operation for detector construction and cosmic rays tests. The paper describes the detailed features of the SCS and preliminary results of operation of a reduced set of hardware which confirm the scalability to the full detector. [ABSTRACT FROM AUTHOR]

The Endcap Disc DIRC (EDD) for PANDA has been designed to identify traversing pions, kaons and protons in the future PANDA experiment. Its central part is a 2 cm thick fused silica plate. Focussing optics are attached to the outer rim of the plate, outside of the acceptance of the experiment. Fast, high-resolution MCP-PMTs, designed to register single Cherenkov photons, have been tested in magnetic field. Filters limit the spectral acceptance of the sensors to reduce dispersion effects and to extend their lifetime. A compact and fast readout is realized with ASICs. Analytical reconstruction algorithms allow for fast particle identification. The angular resolution of a DIRC prototype has been simulated in Monte Carlo and confirmed in a test beam. The final detector will be able to provide a 4 σ π / K separation up to a momentum of 4 GeV / c . [ABSTRACT FROM AUTHOR]

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capabilities in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the Jefferson Lab upgraded 12 GeV continuous electron beam accelerator facility. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely-packed and highly-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The status of the aerogel mass-production and the assessment studies of the aerogel optical performance are here reported. [ABSTRACT FROM AUTHOR]

Novel Cherenkov detector upgrades favour GEM and ThickGEM (THGEM) based MPGD systems. These detectors have reduced ion backflow, fast signal formation, high gain, and could suppress the MIP signals as well. Sources of concern are the possible inefficiencies of the photo-electron collection from the top of the THGEM and the local variation of the gain related to geometrical non-uniformity. The developed high resolution scanner using a focused UV light gave the possibility to study single photo-electron response of MPGDs in the submillimeter scale. Revealing the microstructure of photo-efficiency and local gain provides a new tool to quantitatively compare different THGEM geometries and field-configurations, and thus optimize the detector parameters. The presentation described the key elements of the scanning system and focus, in particular, on the microstructure evolution of different Thick-GEM configurations providing optimization recipes. [ABSTRACT FROM AUTHOR]

The Time-of-Propagation (TOP) detector is a new type of ring-imaging Cherenkov detector developed for particle identification in the barrel region of the Belle II spectrometer. In the assembly and installation, it is crucial for the detector performance to achieve precision alignment and secure gluing of the optical components as well as to mechanically support them managing the stress, attitude, optical and electrical contacts, and limited installation space. Various efforts were made to develop the procedures and jigs along with the development of the mechanical structure. Such efforts accomplished the assembly and installation in April and May 2016, respectively, without a significant incident. [ABSTRACT FROM AUTHOR]

Imaging Atmospheric Cherenkov Telescopes (IACTs) represent a class of instruments which are dedicated to the ground-based observation of cosmic VHE gamma ray emission based on the detection of the Cherenkov radiation produced in the interaction of gamma rays with the Earth atmosphere. One of the key elements of such instruments is a pixelized focal-plane camera consisting of photodetectors. To date, photomultiplier tubes (PMTs) have been the common choice given their high photon detection efficiency (PDE) and fast time response. Recently, silicon photomultipliers (SiPMs) are emerging as an alternative. This rapidly evolving technology has strong potential to become superior to that based on PMTs in terms of PDE, which would further improve the sensitivity of IACTs, and see a price reduction per square millimeter of detector area. We are working to develop a SiPM-based module for the focal-plane cameras of the MAGIC telescopes to probe this technology for IACTs with large focal plane cameras of an area of few square meters. We will describe the solutions we are exploring in order to balance a competitive performance with a minimal impact on the overall MAGIC camera design using ray tracing simulations. We further present a comparative study of the overall light throughput based on Monte Carlo simulations and considering the properties of the major hardware elements of an IACT. [ABSTRACT FROM AUTHOR]