田端 誠

地球生命の誕生に，地球外有機物が重要な役割を果たした可能性が議論されている。特に宇宙塵（惑星間塵）は有機物の運び手として重要であると考えられる。たんぽぽ計画は，国際宇宙ステーション曝露部でエアロゲルを用いて高速で飛来する宇宙塵等を捕集し，分析することや，宇宙塵中の有機物の宇宙での安定性を評価するためにアミノ酸関連分子の宇宙曝露を行うこと等を含む日本初のアストロバイオロジー実験であり，2015年5月に実験が開始された。本講演では，その現状と，2016年以降に予定されている帰還後の分析準備について報告する。

A proximity focusing RICH will be installed in the forward direction of the Belle II spectrometer, inside a super conducting solenoid coil with the magnetic field of 1.5 T. Photons emitted in the sequence of two different aerogel radiator layers will be registered by the Hybrid Avalanche Photo Diodes. By detecting more than 11 photons per incident 4 GeV/c pion, with 15 mrad single photon Cherenkov angle resolution, the designed detector should enable an efficient separation of kaons from pions in the wide range of particle momenta from 0.5 GeV/c up to 4 GeV/c, The particle separation will be based on a two-dimensional extended maximum likelihood analysis. The position dependence of the efficiencies for identification of pions and kaons shows a very homogeneous response over the detector area. The performance on the edge of the detector is improved by employing planar mirrors to reflect the Cherenkov photons on the detector plane. The results show that by using a designed detector configuration the kaon pion separation efficiency of more than 95% can be achieved at a very low pion misidentification probability of 1%. In the low momentum region (0.5 GeV/c-0.8 GeV/c) the variation of detected number of photons due to matching of aerogel refractive index and the gaps between the sensitive areas on the detector plane results in a slightly decreased separation efficiency. (C) 2014 Elsevier B.V. All rights reserved.

The Belle II spectrometer, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron-positron collider at KEK in Japan. For the PlD system in the forward region of the spectrometer, a proximity focusing ring-imaging Cherenkov (RICH) counter with an aerogel radiator is being developed. The counter will provide a 4G separation of pions and kaons up to momenta of 4 GeV/c. For the position sensitive photon sensor, a 144 channel Hybrid Avalanche Photo Detector (HAPD) has been developed with Hamamatsu Photonics K.K. The readout electronics is based on the custom developed ASIC. The design of the components is currently being finalized and part of their mass production have already started. Herein, we report the final design of the counter and a prototype test conducted with test beams at DESY. (C) 2014 Elsevier B.V. All rights reserved.

A hybrid photo detector (HARD) has been developed for the aerogel RICH (ARICH) of the Belle II experiment. In the present contribution we report the performance tests in magnetic fields, results of the neutron and gamma irradiation studies, and of aging tests. We also review the production status and plans. (C) 2014 Elsevier B.V. All rights reserved.

This study presents the recent progress made in developing a spiral fiber<br /> tracker (SFT) for use in the experiment TREK/E36 planned at the Japan Proton<br /> Accelerator Research Complex. This kaon decay experiment uses a stopped<br /> positive kaon beam to search for physics beyond the Standard Model through<br /> precision measurements of lepton universality and through searches for a heavy<br /> sterile neutrino and a dark photon. Detecting and tracking positrons and<br /> positive muons from kaon decays are of importance in achieving high-precision<br /> measurements; therefore, we designed and are developing the new tracking<br /> detector using a scintillating fiber. The SFT was completely assembled, and in<br /> a bench test, no dead channel was determined.

This paper reports the recent progress made in developing a spiral fiber<br /> tracker (SFT) for use in the E36 experiment scheduled at the Japan Proton<br /> Accelerator Research Complex (J-PARC). The primary goal of this positive kaon<br /> decay experiment, which uses a stopped kaon beam, is to test lepton flavor<br /> universality to search for physics beyond the Standard Model of particle<br /> physics. For this experiment, we are currently upgrading the E246 apparatus,<br /> which consists of the superconducting toroidal spectrometer previously used at<br /> the High Energy Accelerator Research Organization (KEK), Japan. Conducting<br /> high-precision measurements will rely on efficiently detecting and tracking<br /> charged particles (i.e., positive muons and positrons) from kaon decays.<br /> Combined with the three existing layers of multiwire proportional chambers, the<br /> SFT comprises four layers of ribbons, with each layer containing 1-mm-diameter<br /> double-clad plastic scintillating fibers; the ribbons are spirally wound in two<br /> helicities around the kaon stopping target at the center of the detector<br /> system. Scintillation photons are read out by multipixel photon counters<br /> connected to the scintillating fibers by clear optical fiber extensions. A<br /> preliminary bench test shows that a prototype two-layer fiber ribbon exhibits<br /> 99.6% detection efficiency at the 1-photoelectron threshold. Finally, the SFT<br /> was successfully assembled around the target holder.

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

This study presents the advancement in hydrophobic silica aerogel development<br /> for use as Cherenkov radiators and muonium production targets. These devices<br /> are scheduled for use in several particle- and nuclear-physics experiments that<br /> are planned in the near future at the Japan Proton Accelerator Research<br /> Complex. Our conventional method to produce aerogel tiles with an intermediate<br /> index of refraction of approximately 1.05 is extended so that we can now<br /> produce aerogel tiles with lower indices of refraction (i.e., 1.03-1.04) and<br /> higher indices of refraction (i.e., 1.075-1.08); each with excellent<br /> transparency. A new production method, called pin drying, was optimized to<br /> produce larger area aerogels consistently with an ultrahigh index of refraction<br /> (&gt;1.10). In addition, for use as a thermal-muonium-emitting material at room<br /> temperature, dedicated low-density aerogels were fabricated using the<br /> conventional method.

© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. For the Belle II experiment at the superKEKB accelerator, we have been developing a proximity focusing ring imaging Cherenkov detector using a silica aerogel as a radiator (A-RICH). This counter is designed to be used at the forward end-cap region and to have pion/kaon separation with more than 4-sigma deviations at momenta up to 4 GeV/c. 144-channel Hybrid Avalanche Photo-Detector (HAPD) modules developed with Hamamatsu Photonics K.K. have been adopted as the photon detectors for the A-RICH. We started the mass production of the HAPD since 2013, and we are testing quality of the manufactured HAPDs. As for the readout of about 60,000 channels from the A-RICH, we developed an ASIC for the amplification and digitization of the signals from HAPDs. We had finished the mass production of the ASIC chips. Then we are testing all the ASIC chips before mounting them on the front-end boards attached to HAPDs. The data from several front-end boards will be merged into one board, and are sent to the Belle II central DAQ system. For this purpose, modules called &quot;merger board&quot; located inside the detector are under development. We are developing the firmware for the FPGA and testing it. In this report, current status of the development of HAPDs and readout electronics for the A-RICH are described.

� Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. Radioisotopes have been emitted around Japan due to a nuclear accident at the Fukushima daiichi nuclear power station in March 2011. A problem is the contaminated water including the atomic nucleus which relatively has a long half-life time such as90Sr,137Cs generated from235U used for nuclear fuel. Internal exposures by90Sr are more dangerous than137Cs&#039;s because it has a long biological half-life (49 years). Therefore, real-time90Sr counter has been required. It is relatively easy to identify a nucleus emitting gamma ray, but it is more difficult to identify a nucleus emitting pure beta ray such as90Sr. Typically, measurement of a radioactivity absolute value of90Sr takes a month at least to give a result. At first, we aim to identify90Sr/137Cs by threshold type Cherenkov detection. It needs radiator which has less than 1.0492 of refractive index for identification of β-ray with maximum energy of 2.28 MeV from90Sr and 1.17 MeV from137Cs. Recently, The material satisfying this condition does not exist expect the silica aerogel. We produced a prototype counter and evaluated performance. The sensitivity is observed (5.49 � 0.06) � 10-3Hz/Bq and (1.12 �0.66) � 10-5Hz/Bq of90Sr and137Cs, respectively. And the counter achieved (2.0 � 1.2) � 10-3of sensitivity ratio between90Sr and137Cs.

We propose a positron detector with 8 layers of scintillation fibers whose length is 1 m and whose diameter is 0.2 mm. The shape of this detector is like as endoscope but one layer of fibers is spirally rolled clockwise, and another layer is counter-clockwise. The pitch of inner and outer spiral fibers are 85 and 75mm, respectively. This detector can be installed into the intestines from the anus, and positrons emitted from PET agents can be directly measured. The azimuth angle and z-coordinate of incident positrons are determined from the 4 types of hit fibers. This inspection can be performed at the same time as the standard PET examination.

国際アストロバイオロジーワークショップ2013（第6回日本アストロバイオロジーネットワーク年次研究会）（2013年11月28日-30日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)（ISAS)）, 相模原市, 神奈川県著者人数: 16名資料番号: SA6000008024

The depth of interaction (DOI) PET detector is one way to achieve high resolution image by determining the depth where most of gamma ray energy is deposited in a scintillator. Because a 2D or 3D profile is obtained for each element, the large amount of data makes the image reconstruction difficult. In this study, we propose a new type of DOI PET detector and estimate a photon yield of a channel and the cost of the materials for manufacturing. An element block of the detector consists of 16 slices of inorganic scintillators, one flat panel PMT, wave length shifting fibers and 256 ch position sensitive (PS) PMT per six element blocks. The main principals of this detector are the condition of total reflection and wave length shifter material. We can see the position where photoelectric effect occurred using the scintillation light not satisfying the condition of total reflection. The photons from the position are transmitted to a channel of PS PMT by wave length shifting fibers. With this detector it is expected to achieve ±1.3 mm resolution for x direction, ±1.5 mm resolution for y and z direction. Ideally we can get the information of the position out of a 50×50×24 mm3 element from only 40 bits signal. Unfortunately we could not perform experimented evaluation owing to delay of delivery of the GSO slices from a company. © 2013 IEEE.

We are developing a multi-purpose aerogel Cherenkov counter (M-ACC). M-ACC is a particle identification (PID) device which works in a narrow space and can cover large area with arbitrary shapes. It can also function in a magnetic field. M-ACC has a light guide comprising wavelength shifting fibers (WLSF), and its application is π/Κ identification in high-energy physics experiments, β-ray detection from radioisotope, and so on. We concretely propose a design of M-ACC for LEPS II project. We produced a prototype M-ACC, and measured the performance of it in the LEPS beam line. © 2013 IEEE.

For the Belle II experiment at the superKEKB, we have been developing a proximity focusing ring imaging Cherenkov detector using a silica aerogel as a radiator. A 144-channel Hybrid Avalanche Photo-Detector which is developed with Hamamatsu Photonics K.K. was adopted as the photon detector for the Aerogel RICH counter. We have conducted beam tests in order to evaluate the particle identification performance for the A-RICH system. One of our current concern for the system is a radiation hardness of the HAPD. In order to realize the neutron hardness for 10-year Belle II operation, we have tried to make APDs with a thinner P-layer which is expected to help in reducing the leakage current. As a result, we actually confirmed effects of the improved APD. In this paper, we would alike to report the status of the A-RICH development, especially about the improvement of the HAPD.

第27回宇宙利用シンポジウム (2011年1月24日-25日, 宇宙航空研究開発機構宇宙科学研究所相模原キャンパス), 相模原市, 神奈川県著者人数: 21人資料番号: AA0065129069