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Abstract: A prototype sampling electromagnetic calorimeter (17.1 radiation lengths) for future linear collider experiments was built, using plastic scintillator tiles and 4mm-thick lead absorber. Wavelength-shifting fibers were used to guide the scintillation light into multi-anode photo-multiplier tubes. The calorimeter was tested at the beam test facility of the High Energy Accelerator Research Organization (KEK) in 2004. In this article we present our beam test results for the tile/fiber calorimeter focusing on the linearity in energy response, the energy resolution, position resolution and uniformity across the tile front face. [Copyright &y& Elsevier]

We present a plastic scintillator, developed in collaboration with Carlit Holdings Co., Ltd., that is fabricated using a liquid parent material cured at room temperature by adding a hardener. The new scintillator can incorporate heat-labile functional materials such as gadolinium to enhance neutron sensitivity. The characteristics of the new scintillator, in particular the light yield and attenuation length, were evaluated using a 90 Sr β -ray source. The light yield was measured 7% Anthracene on the basis of a comparison with commercially available scintillator (BC-408) at a distance of 18 cm from the photodetector surface. This light yield is dependent on the distance between the luminous point and the photodetector because of light attenuation. The attenuation length of the Gd-doped scintillator was about 50 cm. [ABSTRACT FROM AUTHOR]

A radiation detector that consists of a conducting polymer derived from an organic semiconductor material was developed. The motivation behind this study was to reduce the detector costs and to find a suitable alternative to large inorganic semiconductor detectors, which are difficult to fabricate. Herein, we report an unprecedented effort made to detect γ -particles using organic semiconductor, polyaniline, sensors. In addition, the novel organic semiconductor sensors also exhibited improved detection of β -particles compared with other conventional sensors. The material density of the sensor was increased to enhance the detection sensitivity. We focused on materials with high electron density and improved the γ and β -particle sensitivity by doping the material with gadolinium oxide (Gd 2 O 3). When the Gd 2 O 3 doped material was used in a hybrid organic–inorganic radiation detector, the detection sensitivity of the detector improved for γ -particles ejected from a 60Co source. Further, an attempt was made to fabricate sensors with improved β -particle sensitivity by adopting several approaches, including doping Gd 2 O 3 , using polyaniline with fine-tuned oxidation states, and modifying electrode designs. The target detector efficiency of 20% was achieved in the environment of a university laboratory, which is necessary to commercialize the organic radiation sensor. [ABSTRACT FROM AUTHOR]

We have developed a new germanium (Ge) detector unit for hypernuclear γ-ray spectroscopy at J-PARC, which comprises a new Ge detector array Hyperball-J. A compact pulse-tube refrigerator is coupled to a coaxial Ge detector in order to achieve lower crystal temperatures as a means to increase radiation hardness. The obtained crystal temperature is 72 K, while an energy resolution is maintained at (FWHM) 3.1(1) keV for 1.33 MeV γ rays using a gate-integrated shaping amplifier (ORTEC 973U). Gain shifts with changing crystal temperature are also confirmed for the Ge detector. [ABSTRACT FROM AUTHOR]

Abstract: We have constructed a shower maximum detector (SMD) using 1-cm wide scintillating strips. The SMD measures the position of electrons and photons in the electromagnetic calorimeter, and improves the separation capability. We use avalanche photodiodes (APDs) to read out the scintillation light; they are directly attached to each end of a strip so as to construct a compact detector. We operate the SMD at room temperature. This report describes the structure of the SMD and its performance as measured in beam tests for future linear collider experiments. [Copyright &y& Elsevier]

Abstract: We are studying the performance of an electromagnetic calorimeter for the linear collider detector that uses plastic scintillator tiles as active media. To establish fabrication technique we built a thin test module. We then studied the uniformity of the module response as well as its position resolution at a test beam facility at the High-Energy Accelerator Research Organization. [Copyright &y& Elsevier]

We, in collaboration with Carlit Holdings Co., Ltd., developed a new plastic scintillator that can be cured at room temperature by mixing a base resin with a hardener solution. We evaluated the scintillator's characteristics of light yield, stability, and attenuation length using a 90Sr β -ray source. The plastic scintillator showed 40% of the light yield of the commercially available scintillator BC408, or 26% of that of the standard organic scintillator anthracene. The long-term light stabilities of the plastic scintillators, with and without the doping stabilizer agent 2,6-di- tert -butyl-4-methylphenol (BHT), were measured for 6 months. The BHT-doped sample retained 80% of the initial light yield over this period. The initial attenuation length of 0.9 m was obtained. The new plastic scintillator showed good stability against oxidative environments, although improvements in its light yield and attenuation length could be achieved by further optimizing its component materials and processing. [ABSTRACT FROM AUTHOR]