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In 2014 the fully installed ASHIPH (Aerogel, SHifter, PHotomultiplier) system began its operation in the KEDR experiment at the VEPP-4 M e + e − -collider. The system contains 1000 liters of aerogel with refractive index n=1.05 in 160 counters that are arranged in two layers. Cherenkov light collection is preformed by means of wavelength shifters (WLS). 160 Micro-Channel Plate (MCP) PMTs with multialkali photocathode are used as photodetectors. Efficiency of relativistic particles detection was measured with e + e − → e + e − events and cosmic muons. Detection efficiency for under-threshold particles was measured with cosmic muons. From these data π / K -separation of 4 σ at the momentum 1.2 GeV/c was obtained. [ABSTRACT FROM AUTHOR]

The work concerns the development of aerogel radiators for RICH detectors. Aerogel tiles with a refractive index of 1.05 were tested with a RICH prototype on the electron beam on the VEPP-4M collider. It has been shown that polishing with silk tissue yields good surface quality, the amount of light loss at this surface being about 5–7%. The Cherenkov angle resolution was measured for a tile in two conditions: with a clean exit face and with a polished exit face. The number of photons detected was 13.3 and 12.7 for the clean and polished surfaces, respectively. The Cherenkov angle resolution for the polished surface is 55% worse, which can be explained with the forward scattering on the polished surface. A tile with a crack inside was also tested. The experimental data show that the Cherenkov angle resolution is the same for tracks crossing the crack area and in a crack-free area. [ABSTRACT FROM AUTHOR]

In June 2012 a FARICH prototype from Philips Digital Photon Counting (PDPC) based on a photon camera with dimensions of 200×200 mm has been tested at CERN. Remarkable particle separation has been achieved with a 4-layer aerogel sample: the π /K separation at a 6 GeV/ c momentum is 3.5 σ , the μ / π separation is 5.3 σ at 1 GeV/ c . The analysis of the data has shown that the main contribution to the accuracy of the ring radius measurement comes from aerogel. The development of focusing aerogels is proceeding in two main directions: tuning of production technology of multilayer blocks and development of a new production method with continuous density (refractive index) gradient along the block depth. The beam test was carried out in December 2012–January 2013 at the electron beam test facility at the VEPP-4 M e + e − collider. The goal of this test was to measure different single layer and focusing aerogel samples, both multilayer and gradient. Aerogel samples were tested with a PDPC FARICH prototype. A part of DPC SPADs in each pixel was disabled to form an active area of 1×1 mm 2 . The collected data proved that gradient aerogel samples focus Cherenkov light. [ABSTRACT FROM AUTHOR]

In June 2012 we tested a Focusing Aerogel RICH detector prototype based on Digital Photon Counters (DPC) by Philips at the CERN PS T10 beam line with a particle momentum up to 6GeV/c. The prototype comprises a 20×20cm2 photon detector with 48×48 DPC pixels. In order to reduce the dark count rate, the photon detector was cooled to −40°C in addition to disabling individual DPC's microcells. A four layer focusing aerogel radiator with 200mm focal distance was studied. We obtained a Cherenkov angle resolution of 3.61±0.04mrad. The mean number of photoelectrons in a ring is 12. Directly measured separation at 6GeV/c momentum is , separation is at 1GeV/c. A comparison with a Monte Carlo simulation is presented as well. [ABSTRACT FROM AUTHOR]

Abstract: The work is devoted to the development of the Focusing Aerogel RICH (FARICH). The option of the forward RICH for the SuperB project in Italy is presented. It features an aerogel-NaF radiator and MCP photodetectors. Monte Carlo simulation predicts the / K separation at the level better than from 0.2 to 7GeV/c, the / separation—from 0.13 to 1.3GeV/c, and the kaon momentum measurement with an accuracy of about 1% at 1GeV/c. FARICH for the Super Charm-Tau Factory project in Novosibirsk is proposed. Monte Carlo simulation predicts separation at the level better than for a momentum from 0.3 to 1.7GeV/c. A prototype will be tested on the new electron test beam facility at VEPP-4M collider. [Copyright &y& Elsevier]

Abstract: Lately aerogel samples of refractive index as high as 1.13 were synthesized in Novosibirsk. Light scattering length for some samples approaches 12cm. We performed a Geant4 simulation for a FARICH with aerogel of 1.10 index of refraction. Two photodetector options were considered: Burle MCP PMT and a novel photodetector—Hamamatsu MPPC. It is shown that FARICH with MPPC photodetector is able to separate at level pions and kaons up to 8GeV/c, muons and pions up to 1.5GeV/c momentum. The project of Forward RICH for SuperB factory based on focusing aerogel radiator is presented. It is demonstrated that using a FARICH detector for the momentum measurement the momentum precision can be significantly improved. [Copyright &y& Elsevier]

Abstract: The method of improvement of Cherenkov angle resolution in RICH detectors using ‘focusing’ aerogel radiators (FARICH) is under investigation. The ‘focusing’ three-layer aerogel radiator was investigated using a digital radiographic device. The Monte Carlo calculations of velocity resolution based on measured variations of the refractive index in aerogel tile are presented. With the observed variations, - and K-mesons can be separated up to 8.4GeV/c, - and -mesons can be separated up to . We studied the use of sodium fluoride radiator in a RICH detector. NaF radiator extends the working momentum region for the identification down to 0.6GeV/c. It has been shown that a RICH detector with NaF radiator can achieve a competitive velocity resolution up to 5GeV/c as compared to single-layer aerogel RICH. [Copyright &y& Elsevier]

Abstract: Our group produces silica aerogels with refractive indices of 1.006–1.13 with good optical transparency. The particle identification systems for the KEDR and the SND detectors based on threshold aerogel counters are described. Cosmic test results for the SND counters are presented. The possibility of employing a RICH with a sodium fluoride crystal radiator for separation up to momentum is explored. The combined NaF-aerogel radiator is proposed to decrease the minimum working momentum of the RICH below the Cherenkov threshold in aerogel. [Copyright &y& Elsevier]

Abstract: The work on aerogel Cherenkov counters was started in Novosibirsk in 1986. Production of aerogels with refractive indices of 1.006–1.13 and thicknesses of blocks up to 50mm was developed. The light absorption length at 400nm is 5–7m, the scattering length is 4–5cm. By these parameters, the Novosibirsk aerogel is one of the best in the world. The ASHIPH Cherenkov counters with light collection on wavelength shifters have been developed. The ASHIPH system of the KEDR detector contains 1000l of aerogel. The separation is . A project of ASHIPH counters for the SND detector has been developed. Aerogel RICH for LHCb gives a possibility to identify hadrons in the momentum range of 2–10GeV/c. The Novosibirsk group is developing an aerogel RICH for the endcap for the SuperBaBar project. Calculations performed by a group of physicists from Novosibirsk and DESY-Zeuthen have shown that aerogel radiators enable to achieve time resolution up to 20fs. [Copyright &y& Elsevier]

Abstract: The development of aerogel Cherenkov counters with the light collection using a wavelength shifter is described. 80 counters of this type are working in the KEDR detector. A project of similar counters for the SND detector based on “heavy” aerogel with has been developed. Aerogel with a refractive index of 1.006–1.13 and dimensions of blocks up to is produced by the Novosibirsk group for use in Cherenkov counters of different types. The Novosibirsk group is participating in the development of LHCb RICH as well as a beam diagnostics for a photo-injector test facility at DESY–Zeuthen. Recently we started development of RICH based on focusing aerogel (FARICH) for the endcap of the SuperBaBar. For the first time in the world the focusing aerogel with layers of different refractive indices has been produced. [Copyright &y& Elsevier]

Abstract: In this work we investigate a Ring Imaging Cherenkov detector based on “focusing” aerogel (FARICH). In the proximity focusing RICH, one of the main factors determining precision of ring radius measurements is a finite thickness of a radiator. FARICH development aims at the reduction of this effect by means of using multilayer aerogel. Two options have been considered. Single ring: refraction index and thickness of each layer are adjusted in such a way that Cherenkov rings from different layers are superimposed on each other. Multi-ring: refraction index and thickness of each layer are adjusted so that ring images from different layers have different radii and are clearly separated from each other. For the first time in the world we have developed a technique for production of multilayer aerogels (SAN-MULTI). A few samples consisting of four aerogel layers with indices from 1.022 to 1.030 have been produced. A GEANT4 based simulation program has been developed. Velocity resolution was investigated for different momenta and particle incidence angles. It was shown that velocity resolution of is achievable. This permits us to have separation at the level of more than up to momentum separation up to momentum . [Copyright &y& Elsevier]

Cherenkov counters based on Aerogel, wavelength SHIfter, and PHotomultipliers (ASHIPH) for the KEDR detector are described. As compared with the direct light collection on PMT, the ASHIPH method allows us to diminish the number of PMTs essentially. The quality of the particle identification with the ASHIPH counters was tested. The π/K separation is 4.5σ for the momentum 1.2 GeV/c. The mass production of the ASHIPH counters was organized in Budker Institute of Nuclear Physics (Novosibirsk, Russia). 80 counters filled with 500 ls of aerogel have been produced and tested with cosmic muons. These counters were installed into the KEDR detector in 2003. The stability of the micro-channel PMTs without protecting layer was studied. The first results on a long-term stability of the ASHIPH counters filled with the hygroscopic aerogel are presented. [Copyright &y& Elsevier]

The status of the ASHIPH (Aerogel, wavelength SHIfter, and PHotomultipliers) system of the KEDR detector is described. The measurement of the quality of the particle identification with the ASHIPH counters was performed. The π/K separation is 4.5σ for the momentum 1.2 GeV/c and 4.7σ for the momentum 0.86 GeV/c. Timing properties of the ASHIPH counter are measured. The time resolution for pions is 2 ns, and the BBQ decay time is 15 ns. The advantages and disadvantages of Cherenkov counters filled with aerogel crumb are discussed. The process of the mass counter production for the KEDR detector is described. [Copyright &y& Elsevier]

The project of Cherenkov counters based on Aerogel, wavelength SHIfter, and PHotomultipliers (ASHIPH) for the KEDR detector is described. The quality of particle identification with the ASHIPH counters has been measured for the first time. Tests have been carried out at the Dubna accelerator. For a momentum of 1.2 GeV/c, the π/K separation is 4.5σ. In comparison with direct light collection on PMTs, the ASHIPH method allows to diminish the number of PMTs essentially. [Copyright &y& Elsevier]

Abstract: A threshold Cherenkov counter based on dense aerogel with refraction index n=1.13 is described. This counter is used for kaon identification at momenta below 1GeV/c in the SND detector, which takes data at the VEPP-2000 e+e− collider. The results of measurements of the counter efficiency using electrons, muons, pions, and kaons produced in e+e− annihilation are presented. [Copyright &y& Elsevier]

Abstract: The paper is devoted to the cosmic muon tests of particle identification system for the SND detector at the new VEPP-2000 e+e− collider. The goal of the tests is to measure average signal for the relativistic particles. The measurements of the average signal were done at five different points of the counter. Obtained values of the signal are close to 10 photoelectrons. Preliminary results for misidentification probability for and K mesons with the energy of 1000MeV are presented. [ABSTRACT FROM AUTHOR]

Abstract: The paper is devoted to the cosmic tests of particle identification system for the SND detector at VEPP-2000. The goal of the tests is to measure main parameters of the system: average signal for the relativistic particles, nonuniformity of the light collection, and time resolution. The measurements of the average signal were done in five points of the counter. The obtained value of the signal is about 10 photoelectrons. The time resolution is about 2ns. The time dependence of the average amplitude was measured also. It was shown that average amplitude of the signal decreases with characteristic time of about two years. The cause of the signal decrease is discussed. [Copyright &y& Elsevier]

The Super Charm–Tau (SCT) Factory is a proposed electron–positron collider in Novosibirsk with a peak luminosity of 1 0 35 cm − 1 s − 1 operating in the energy range between 2and 6 GeV. The interaction region should be equipped by an excellent universal particle detector meeting the requirements of broad physics program of the experiment. Research and development for all detector subsystems is currently underway. Particle identification (PID) system of the detector is required to provide the state-of-the-art level of μ / π separation for the particle momenta up to 1. 2 GeV∕c. The following options for the PID system are considered in this paper: focusing aerogel ring imaging Cherenkov (FARICH) detector composed of 4-layer aerogel tiles, threshold Cherenkov counters based on aerogel shifter photomultiplier (ASHIPH), and time-of-flight (ToF) detector combined with the time-of-propagation (ToP) approach providing a time resolution better than 30 ps. Assessment of the charged particle separation performance for these options based on simulation and prototype tests results is presented. [ABSTRACT FROM AUTHOR]

The particle identification system ASHIPH (Aerogel, SHifter, PHotomultiplier) has been working in the KEDR experiment at VEPP-4M collider (Budker INP, Novosibirsk) since 2014. The system consists of 160 counters arranged in two layers and covers the 96% of the solid angle. Two layer system permits to use different approaches for π /K separation. Three such approaches are described. The status of the system is presented. Main system parameters such as BhaBha suppression factor, π /K separation power, relativistic particle detection efficiency were measured with help of cosmic particles and experimental data collected at the peak of J/ ψ -meson. π /K separation in the momentum range from 0.95 to 1.45 GeV/ c is better than 4 σ. Monte-Carlo simulation procedures are described and results are presented as well. [ABSTRACT FROM AUTHOR]

A high performance particle identification (PID) system is essential for the successful realization of the broad physics program at the future Super C- τ Factory in Novosibirsk. The main requirements for the PID system are as follows: good π / K -separation in the entire operational momentum range and good μ ∕ π -separation in the momentum range from 0.3 to 1.2 GeV/ c. The RICH detector based on focusing aerogel radiator (FARICH) and position-sensitive photon detector meets all these requirements. The FARICH method is described, and the beam test results are presented. The FARICH system design outline for the Super C- τ Factory project is presented. Most promising photon detector options are considered. [ABSTRACT FROM AUTHOR]

Aerogel for different types of Cherenkov detectors is produced by a collaboration of Budker Institute of Nuclear Physics and Boreskov Institute of Catalysis during more than two decades. So far only the production of two sizes was possible in large numbers: 50 × 50 and 115 × 115 mm 2. This work is devoted to the development of the production technology of large scale aerogel radiators for use in the Ring-imaging Cherenkov (RICH) detectors. These detectors require additional parameters to be controlled for each aerogel tile during production. Procedures of measurement of the aerogel tiles refractive index, the light scattering length, the upper surface flatness are described. [ABSTRACT FROM AUTHOR]

Particle identification power of modern aerogel RICH detectors strongly depends on optical quality of radiators. It was shown that wavelength dependence of aerogel tile transparency after polishing cannot be described by the standard Hunt formula. The Hunt formula has been modified to describe scattering in a thin layer of silica dust on the surface of aerogel tile. Several procedures of polishing of aerogel tile have been tested. The best result has been achieved while using natural silk tissue. The resulting block has optical smooth surfaces. The measured decrease of aerogel transparency due to surface scattering is about few percent. This result could be used for production of radiators for the Focusing Aerogel RICH detectors. [ABSTRACT FROM AUTHOR]

We present our current experience in preparation of focusing aerogels for the Focusing Aerogel RICH detector. Multilayer focusing aerogel tiles have been produced in Novosibirsk by a collaboration of the Budker Institute of Nuclear Physics and Boreskov Institute of Catalysis since 2004. We have obtained 2–3–4-layer blocks with the thickness of 30–45 mm. In 2012, the first samples of focusing blocks with continuous density (refractive index) gradient along thickness were produced. This technology can significantly reduce the contribution from the geometric factor of the radiator thickness to the resolution of the measured Cherenkov angle in the FARICH detector. The special installation was used for automatic control of reagents ratio during the synthesis process. The first samples were tested using the digital radiography method and on the electron beam with the FARICH prototype. [ABSTRACT FROM AUTHOR]

Abstract: Silica aerogel blocks are being produced for use in Cherenkov detectors by a collaboration of Boreskov Institute of Catalysis and Budker Institute of Nuclear Physics since 1986. Novosibirsk aerogel is used in several detectors; among them are KEDR, SND (BINP, Novosibirsk), LHCb (CERN, Geneva), AMS (for International Space Station mission) and others. Currently our investigations are going on in two directions: multilayer aerogels for Focusing Aerogel RICH and aerogels with high index of refraction. We have synthesized two-, three- and four-layer aerogel tiles with dimensions of 115mm×115mm. We have modernized the method of pinhole drying for preparation of aerogels with refractive index in the range of 1.07–1.20. [Copyright &y& Elsevier]

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]