I. Adachi

Hydrophobic silica aerogel production at KEK

Abstract We present herein a characterization of a standard method used at the High Energy Accelerator Research Organization (KEK) to produce hydrophobic silica aerogels and expand this method to obtain a wide range of refractive index ( n =1.006–1.14). We describe in detail the entire production process and explain the methods used to measure the characteristic parameters of aerogels, namely the refractive index, transmittance, and density. We use a small-angle X-ray scattering (SAXS) technique to relate the transparency to the fine structure of aerogels.

Silica aerogel radiator for use in the A-RICH system utilized in the Belle II experiment

Abstract This paper presents recent progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter, which will be installed in the forward end cap of the Belle II detector. The proximity-focusing A-RICH system is especially designed to identify charged kaons and pions. The refractive index of the installed aerogel Cherenkov radiators is approximately 1.05, and we aim for a separation capability exceeding 4σ at momenta up to 4xa0GeV/c. Large-area aerogel tiles (over 18×18×2xa0cm3) were first fabricated in test productions by pin drying in addition to conventional methods. We proposed to fill the large end-cap region (area 3.5xa0m2) with 124 water-jet-trimmed fan-shaped dual-layer-focusing aerogel combinations of different refractive indices (1.045 and 1.055). Guided by the test production results, we decided to manufacture aerogels by the conventional method and are currently proceeding with mass production. In an electron beam test undertaken at the DESY, we confirmed that the K/π separation capability of a prototype A-RICH counter exceeded 4σ at 4xa0GeV/c.

Large-area silica aerogel for use as Cherenkov radiators with high refractive index, developed by supercritical carbon dioxide drying

Abstract This study presents the development of large-area (18xa0cmxa0×xa018xa0cmxa0×xa02xa0cm), high refractive index ( n xa0∼xa01.05) hydrophobic silica aerogel tiles for use as Cherenkov radiators. These transparent aerogel tiles will be installed in a Cherenkov detector for the next-generation accelerator-based particle physics experiment Belle II, to be performed at the High Energy Accelerator Research Organization (KEK) in Japan. Cracking has been eliminated from the prototype aerogel tiles by improving the supercritical carbon dioxide (scCO 2 ) extraction procedure when drying the wet gel tiles. Finally, a method of mass-producing aerogel tiles for the actual detector was established. It was confirmed that the experimentally manufactured aerogel tiles meet the required optical and hydrophobic characteristics and have a uniform tile density.

Particle identification performance of the prototype aerogel RICH counter for the Belle II experiment

We have developed a new type of particle identification device, called an aerogel ring imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov radiators. For detection of Cherenkov photons, hybrid avalanche photo-detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron and

Recent progress in the development of large area silica aerogel for use as RICH radiator in the Belle II experiment

gamma

Study of 144 Channel Multi-Anode Hybrid Avalanche Photo-Detector for the Belle II RICH Counter

-ray radiation that exceeds the levels expected in the 10-year Belle II operation. In order to confirm the basic performance of the ARICH counter system, we carried out a beam test at the using a prototype of the ARICH counter with six HAPD modules. The results are in agreement with our expectations and confirm the suitability of the ARICH counter for the Belle II experiment. Based on the in-beam performance of the device, we expect that the identification efficiency at

Aerogel RICH for the Belle II forward PID

3.5,{rm GeV}/c

Readout ASIC and electronics for the 144ch HAPD for Aerogel RICH at Belle II

is 97.4% and 4.9% for pions and kaons, respectively. This paper summarizes the development of the HAPD for the ARICH and the evaluation of the performance of the prototype ARICH counter built with the final design components.

Aerogel RICH for forward PID at Belle II

We report recent progress in the development of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter to be installed in the forward end cap of the Belle II detector, which is currently being upgraded at the High Energy Accelerator Research Organization (KEK), Japan. The production of approximately 450 aerogel tiles with refractive indices of either 1.045 or 1.055 was completed in May, 2014, and the tiles are now undergoing optical characterization. Installation of the aerogels was tested by installing them into a partial mock-up of the support structure.

Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

I. Adachi∗a, R Dolenecb, K. Haraa, M. Higuchic, T. Iijimad, S. Iwatae, H. Kakunoe, H. Kawai f , T. Kawasakig, S. Korparb,h, P. Križanb,i, T. Kumitae, S. Nishidaa, W. Mori j, S. Ogawa j, R. Pestotnikb, Y. Sakashitae, L. Santeljb, A. Seljakb, T. Sumiyoshie, H. Takagakie, M. Tabata f ,k, Y. Yusag, R. Verheydenb a) IPNS, High Energy Accelerator Research Organization (KEK), Tsukuba, Japan b) Jožef Stefan Institute, Ljubljana, Slovenia c) Tokyo University of Science, Noda, Japan d) Nagoya University, Nagoya, Japan e) Tokyo Metropolitan University, Hachioji, Japan f ) Chiba University, Chiba, Japan g) Niigata University, Niigata, Japan h) University of Maribor, Maribor, Slovenia i) University of Ljubljana, Ljubljana, Slovenia j) Toho University, Funabashi, Japan k) Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan E-mail: ichiro.adachi@kek.jp