[en] Highlights: • Fully depleted and non-fully depleted photodiodes were designed and fabricated. • The FD sensor has the advantage of a large active volume and low capacitance. • The NFD sensor has a lower power consumption and is cost effective. • The fabricated photodiodes can be used for x-ray detector in cargo system. • Electrical characteristics, quantum efficiencies and energy resolutions are measured. In this study, we manufactured silicon PIN photodiodes coupled with a scintillator for X-ray detection in cargo inspections. The classification of photodiodes is made based on their depletion characteristics into two categories: fully depleted (FD) sensor and non-fully depleted (NFD) sensor. We manufactured the photodiodes on an n-type silicon wafer of diameter 6-in., a high resistivity ($>5\mathrm{k}\mathrm{\Omega }\mathrm{cm}$) and low resistivity ($>100\mathrm{\Omega }\mathrm{cm}$) for the FD and NFD sensors, respectively. The light entrance windows for the scintillation light were designed on the ohmic and junction sides of the FD and NFD sensors, respectively. Since the NFD sensor is not fully depleted, it can be operated at a lower bias voltage, and therefore has a lower leakage current. We measured the electrical characteristics, quantum efficiencies, and energy resolutions of the fabricated FD and NFD photodiodes coupled with or without a CsI(Tl) crystal using alpha particles from a ²⁴¹Am radioactive source. We present results of the comparison between the FD and NFD sensors.

[en] Highlights: • Single-sided silicon photostrip sensors are designed and fabricated. • The fabricated photostrip sensors are sufficient enough to provide 2D position information. • Signal ratios between two photostrip sensors are well-separated. • 2D position and depth of interaction are measured using photostrip sensors and a scintillator. • The depth of interaction by gamma irradiation in the scintillator is simulated by using Geant4. The photoelectric absorption of gamma rays in silicon occurs with such low probability that scintillation material is employed in the photostrip detector. We fabricate single-sided photostrip sensors which are sensitive to visible light. Two photodetectors in a photon counting mode are optically coupled with the scintillator with a sandwich structure. The photostrip sensors have 128 strips, a $200\mathrm{\mu }\mathrm{m}$ strip pitch and a size of $3.8\times 2.8{\mathrm{cm}}^2$. Sensor signals are read by a 128-channel VA1TA3 readout chip. A CsI(Tl) crystal is then optically combined to measure both of depths of interaction (DOI) and 2-D images, while the position of the LED are varied. We also performed a simulation of gamma ray irradiation at different locations inside the scintillator using the GEANT4 Monte Carlo simulation tool. We measured the 2-D position of incoming light with two photostrip sensors, and also measured the DOI and 2-D position of scintillating light by placing a scintillator between the photostrip sensors. The DOI measurement results and the GEANT4 simulation results were compared.

[en] The Cosmic Ray Energetics And Mass (CREAM) mission is planned for launch in 2015 to the International Space Station (ISS) to research high-energy cosmic rays. Its aim is to understand the acceleration and propagation mechanism of high-energy cosmic rays by measuring their compositions. The Top Counting Detector and Bottom Counting Detector (T/BCD) were built to discriminate electrons from protons by using the difference in cascade shapes between electromagnetic and hadronic showers. The T/BCD provides a redundant instrument trigger in flight as well as a low-energy calibration trigger for ground testing. Each detector consists of a plastic scintillator and two-dimensional silicon photodiode array with readout electronics. The TCD is located between the carbon target and the calorimeter, and the BCD is located below the calorimeter. In this paper, we present the design, assembly, and performance of the T/BCD

[en] The Cosmic Ray Energetics and Mass (CREAM) experiment at the International Space Station (ISS) aims to elucidate the source and acceleration mechanisms of high-energy cosmic rays by measuring the energy spectra from protons to iron. The instrument is planned for launch in 2015 at the ISS, and it comprises a silicon charge detector, a carbon target, top and bottom counting detectors, a calorimeter, and a boronated scintillator detector. The top and bottom counting detectors are developed for separating the electrons from the protons, and each of them comprises a plastic scintillator and a 20×20 silicon photodiode array. Each photodiode is 2.3 cm×2.3 cm in size and exhibits good electrical characteristics. The leakage current is measured to be less than 20 nA/cm"2 at an operating voltage. The signal-to-noise ratio is measured to be better than 70 using commercial electronics, and the radiation hardness is tested using a proton beam. A signal from the photodiode is amplified by VLSI (very-large-scale integration) charge amp/hold circuits, the VA-TA viking chip. Environmental tests are performed using whole assembled photodiode detectors of a flight version. Herein, we present the characteristics of the developed photodiode along with the results of the environmental tests

[en] A silicon vertex detector (SVD) for the Belle-II experiment comprises four layers of double-sided silicon strip detectors (DSSDs), assembled in a ladder-like structure. Each ladder module of the outermost SVD layer has four rectangular and one trapezoidal DSSDs supported by two carbon-fiber ribs. In order to achieve a good signal-to-noise ratio and minimize material budget, a novel chip-on-sensor “Origami” method has been employed for the three rectangular sensors that are sandwiched between the backward rectangular and forward (slanted) trapezoidal sensors. This paper describes the bonding procedures developed for making electrical connections between sensors and signal fan-out flex circuits (i.e., pitch adapters), and between pitch adapters and readout chips as well as the results in terms of the achieved bonding quality and pull force. - Highlights: • Gluing and wire binding for Belle-II SVD are studied. • Gluing robot and Origami module are used. • QA are satisfied in terms of the achieved bonding throughput and the pull force. • Result will be applied for L6 ladder assembly.

[en] This paper describes an investigation into gluing and wire bonding for assembling the Silicon Vertex Detector (SVD) for the Belle II experiment at KEK in Japan. Optimizing the gluing of the silicon microstrip sensors, the support frame, and the readout flex cables is important for achieving the required mechanical precision. The wire bonding between the sensors and the readout electronic chips also needs special care to maximize the physics capability of the SVD. The silicon sensors and signal fan out flex circuits (pitch adapters) are glued and connected using wire bonding. We determine that gluing quality is important for achieving good bonding efficiency. The standard deviation in the glue thickness for the best result is measured to be 3.11 μm. Optimal machine parameters for wire bonding are determined to be 70 mW power, 20 gf force, and 20 ms for the pitch adapter and 60 mW power, 20 gf force, and 20 ms for the silicon strip sensors; these parameters provide a pull force of (10.92±0.72) gf. With these settings, 75% of the pitch adapters and 25% of the strip sensors experience the neck-broken type of break

[en] We study bottomonium production in association with an η meson in e⁺e^- annihilations near the Υ(5S), at a centre-of-mass energy of √(s) = 10.866 GeV. The results are based on the 121.4 fb^-1 data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the η meson is reconstructed and the missing-mass spectrum of η candidates is investigated. We observe the e⁺e^- → ηΥ_J(1D) process and find evidence for the e⁺e^- → ηΥ(2S) process, while no significant signals of Υ(1S), h_b(1P), nor h_b(2P) are found. Cross sections for the studied processes are reported. (orig.)

[en] We report evidence for the charged charmed-strange baryon Ξ_c(2930)⁺ with a signal significance of 3.9σ with systematic errors included. The charged Ξ_c(2930)⁺ is found in its decay to K_S⁰Λ_c⁺ in the substructure of anti B⁰ → K⁰_SΛ_c⁺ anti Λ_c^- decays. The measured mass and width are [2942.3 ± 4.4(stat.) ± 1.5(syst.)] MeV/c² and [14.8 ± 8.8(stat.) ± 2.5(syst.)] MeV, respectively, and the product branching fraction is B(anti B⁰ → Ξ_c(2930)⁺ anti Λ_c^-) B(Ξ_c(2930)⁺ → anti K⁰Λ_c⁺) = [2.37 ± 0.51(stat.) ± 0.31(syst.)] x 10^-4. We also measure B(anti B⁰ → anti K⁰Λ_c⁺ anti Λ_c^-) = [3.99 ± 0.76(stat.) ± 0.51(syst.)] x 10^-4 with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, Y_η, in the Λ_c⁺ anti Λ_c^- invariant mass spectrum. No clear signals of the Y(4660) or Y_η are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. Thesemeasurements are obtained from a sample of (772 ± 11) x 10⁶ B anti B pairs collected at the Υ(4S) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider. (orig.)