Kyo Tsukada

Study of a threshold Cherenkov counter based on silica aerogels with low refractive indices

Abstract To identify π ± and K ± in the region of 1.0−2.5 GeV/ c , a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and checked its properties in a test beam. The results obtained demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to π K separation up to a few GeV/ c with an efficiency greater than 90% was considered.To identify π ± and K ± in the region of 1.0 ∼ 2.5 GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to π/K separation up to a few GeV/c with an efficiency greater than 90 % was considered. 1 Introduction Recently, asymmetric e + e − colliders with high luminosities to explore CP violation in B meson system(B-factory) have been proposed[1, 2]. In a B-factory detector, an identification of the particle species is an important issue. In particular, the separation of π ± and K ± in the momentum region of 1.0 ∼ 2.5 GeV/c is indispensable for studying many B meson decay channels[1]. For this purpose, Cherenkov counter equipped with silica aerogels having a low refractive index is one of the most promising devices since it has been widely used in high energy experiments[3]. Furthermore, the use of an aerogel Cherenkov counter enables us to reduce the material for a particle identification device which is located in front of an electromagnetic calorimter. The requirements imposed on our aerogel Cherenkov counter are: (i) The refractive index of aerogel(n) should be in the 1.010 ∼ 1.015 range in order to to achieve a π/K separation capability in the region of 1.0 ∼ 2.5 GeV/c. (ii) The optical transparency of the aerogel should be high. Notice that Cherenkov photons emitted by an injected particle becomes significantly small in our case because the Cherenkov light yields are proportional to 1 − 1/n 2. Therefore, the loss of photons in the aerogel due to absorptions and scatterings should be minimized. (iii) Efficient photon collection and detection under a

STUDY ON FINE-MESH PMTS FOR DETECTION OF AEROGEL CHERENKOV LIGHT

Abstract Most recent fine-mesh photomultipliers (FM-PMTs), with 19 dynode stages, have been tested for application to a threshold aerogel Cherenkov counter. Two properties, the gain and the pulse height resolution, have been particularly studied in a magnetic field of up to 1.5 T. The obtained results show that a FM-PMT is a suitable device for detection of aerogel Cherenkov light.

Photo-production of neutral kaons on 12C in the threshold region

Abstract The kaon photo-production process on 12C has been studied by measuring neutral kaons in the photon energy range of 0.8–1.1 GeV. Neutral kaons were identified by the invariant mass constructed from two charged pions emitted in the K S 0 → π + π − decay channel. The differential and integrated cross sections in the threshold photon energy region were obtained. The obtained momentum spectra were compared with a Spectator model calculation using elementary amplitudes of kaon photo-production given by recent isobar models. The present results provide the first information on the n ( γ , K 0 ) Λ reaction, which is expected to play an important role in constructing models of strangeness production by electromagnetic interactions. The experimental results show that the cross section of C 12 ( γ , K 0 ) is of the same order as that of C 12 ( γ , K + ) and suggest that a slightly backward K 0 angular distribution is favored in the γ n → K 0 Λ process.

Aerogel Cherenkov counter for the BELLE experiment

In the BELLE experiment at KEKB, a threshold Cherenkov counter system based on silica aerogels will be used to provide πK separation in the momentum region from 0.8 to 3.5 GeV/c. The detector design, recent progress in R&D and results of beam tests are reviewed.

The K1.8BR spectrometer system at J-PARC

A new spectrometer system was designed and constructed at the secondary beam line K1.8BR in the hadron hall of J-PARC to investigate

Photoproduction of neutral kaons on C in the threshold region

\bar K N

Radiation damage of silicon microstrip detectors by high doses of 200-MeV electrons

interactions and

The SCRIT electron scattering facility project at RIKEN RI beam factory

\bar K

Energy calibration of tagged photons by the d(γ,π−pp) reaction

-nuclear bound systems. The spectrometer consists of a high precision beam line spectrometer, a liquid

NEUTRAL KAON PHOTOPRODUCTION AT LNS, TOHOKU UNIVERSITY

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