Tomohisa Uchida

Hyper Suprime-Cam

Hyper Suprime-Cam (HSC) is an 870 Mega pixel prime focus camera for the 8.2 m Subaru telescope. The wide field corrector delivers sharp image of 0.25 arc-sec FWHM in r-band over the entire 1.5 degree (in diameter) field of view. The collimation of the camera with respect to the optical axis of the primary mirror is realized by hexapod actuators whose mechanical accuracy is few microns. As a result, we expect to have seeing limited image most of the time. Expected median seeing is 0.67 arc-sec FWHM in i-band. The sensor is a p-ch fully depleted CCD of 200 micron thickness (2048 x 4096 15 μm square pixel) and we employ 116 of them to pave the 50 cm focal plane. Minimum interval between exposures is roughly 30 seconds including reading out arrays, transferring data to the control computer and saving them to the hard drive. HSC uniquely features the combination of large primary mirror, wide field of view, sharp image and high sensitivity especially in red. This enables accurate shape measurement of faint galaxies which is critical for planned weak lensing survey to probe the nature of dark energy. The system is being assembled now and will see the first light in August 2012.

Hardware-Based TCP Processor for Gigabit Ethernet

Transmission Control Protocol (TCP) and Ethernet have been widely used in readout systems. These protocols are de facto standards and have been implemented on standard operating systems. However, some small devices, e.g., front-end devices and detectors, are not capable of employing these protocols because of hardware size limitations. This paper describes a TCP processor for Gigabit Ethernet with a circuit size suitable for implementing on a single Field Programmable Gate Array. The only peripheral device required is a single Ethernet Physical Layer Device. The hardware was implemented and its TCP throughput was measured. The throughputs in both directions simultaneously were at the upper limits of Gigabit Ethernet. The processor described here allows adoption of TCP/Ethernet in small devices that have hardware size limitations.

Hardware-based TCP processor for Gigabit Ethernet

Transmission control protocol (TCP) and Ethernet have been widely used in readout systems. These protocols are de facto standards and have been implemented on standard operating systems. However, some small devices, e.g., front-end devices and detectors, are not capable of employing these protocols because of hardware size limitations. This paper describes a TCP processor for gigabit Ethernet with a circuit size suitable for implementing on a single field programmable gate array. The only peripheral device required is a single Ethernet physical layer device. The hardware was implemented and its TCP throughput was measured. The throughputs in both directions simultaneously were at the upper limits of gigabit Ethernet. A mechanism for slow control over user datagram protocol (UDP) is also provided. The processor described here allows adoption of TCP/Ethernet in small devices that have hardware size limitations.

Development of TCP/IP processing hardware

TCP/IP/Ethernet is a widely used data transfer technology in data acquisition systems. This technology is essential to construct back-end systems. On the other hand, it has not been sufficiently adopted in front-end systems because front-end devices have constraints that are difficult to satisfy. To overcome these constraints, we have developed TCP/IP processing hardware with the following features: high-speed data transfer, small logic size, simple interface, and low power consumption. We implemented the hardware on a field programmable gate array and measured its performance. The measured user data transfer speed is 95 Mbps with 100BASE-T Ethernet, which achieves the theoretical limit. We concluded that the hardware has sufficient performance for front-end devices.

A common data acquisition system for high-intensity beam experiments

The J-PARC facility, which will be ready in 2008, is being constructed to perform a number of experiments including nuclear physics, kaon decays and neutrino oscillation. The expected data acquisition rate ranges from 500 Hz to 10 kHz, which is significantly higher than those used in the existing small experiments at KEK. We have developed a new data acquisition system that can be used in a wide range of experiments at J-PARC. The system consists of a KEK-VME crate, a readout platform module and peripheral modules. The readout platform module is highly modularized, having four slots to install daughter cards for digitization and three PCI mezzanine card (PMC) slots for on-board data processing and other purposes. The performance of the platform module and a model setup of the data acquisition system are reported

Development of an atmospheric Cherenkov imaging camera for the CANGAROO-III experiment

Abstract A Cherenkov imaging camera for the CANGAROO-III experiment has been developed for observations of gamma-ray-induced air showers at energies from 10 11 to 10 14 eV . The camera consists of 427 pixels , arranged in a hexagonal shape at 0.17° intervals, each of which is a 3 4 -in. diameter photomultiplier module with a Winston-cone-shaped light guide. The camera was designed to have a large dynamic range of signal linearity, a wider field of view, and an improvement in photon-collection efficiency compared with the CANGAROO-II camera. The camera, and a number of the calibration experiments made to test its performance, are described in detail in this paper.A Cherenkov imaging camera for the CANGAROO-III experiment has been developed for observations of gamma-ray induced air-showers at energies from 1011 to 10 eV. The camera consists of 427 pixels, arranged in a hexagonal shape at 0.17◦ intervals, each of which is a 3/4-inch diameter photomultiplier module with a Winston-cone–shaped light guide. The camera was designed to have a large dynamic range of signal linearity, a wider field of view, and an improvement in photon collection efficiency compared with the CANGAROO-II camera. The camera, and a number of the calibration experiments made to test its performance, are described in detail in this paper.

Modular pipeline readout electronics for the SuperBelle drift chamber

In order to explore new physics in B-meson decays we plan to upgrade the KEK B-factory to a luminosity of 5/spl times/10/sup 35/ cm/sup -2/ s/sup -1/. In parallel we are developing a new pipelined data acquisition system for the Belle detector to cope with higher trigger rates of up to 30 kHz and severe background conditions. In order to reduce development and maintenance costs, we have adopted a modular design for these new readout electronics. The chosen architecture consists of a common readout platform, upon which are mounted subdetector specific parts, customized to meet the readout requirements of each sub detector component. As an example of this new architecture, we present in this paper the design of drift chamber electronics. The drift chamber readout utilizes the AMT-3 time-to-digital converter chip, originally developed for the ATLAS experiment, which satisfies the performance requirement for current and future Belle drift chamber readout. A data transfer performance test with emulation modules, mounted on the common platform, shows that the new readout electronics works well at a more than 30 kHz input trigger rate.

Detection of diffuse TeV gamma-ray emission from the neaby starburst galaxy NGC 253

Department of Physics, Osaka City University, Osaka, Osaka 558-8585, JapanA&A 396, L1-L4(2002). A&A402, 443-455(2003)ABSTRACTContext.Aims. The CANGAROO-II telescope observed sub-TeV gamma-ray emission from the nearby starburst galaxy NGC 253. The emission regionwas extended with a radial size of 0.3-0.6 degree. On the contrary, H.E.S.S could not confirm this emission and gave upper l imits at the levelof the CANGAROO-II flux. In order to resolve this discrepancy, we analyzed new observational results for NGC 253 by CANGAROO-III andalso assessed the results by CANGAROO-II.Methods. Observation was made with three telescopes of the CANGAROO-III in October 2004. We analyzed three-fold coincidence data bythe robust Fisher Discriminant method to discriminate gamma ray events from hadron events.Results. The result by the CANGAROO-III was negative. The upper limit of gamma ray flux was 5.8% Crab at 0.58 TeV for po int-sourceassumption. In addition, the significance of the excess flux o f gamma-rays by the CANGAROO-II was lowered to less than 4 sigma afterassessing treatment of malfunction of photomultiplier tubes.Key words. gamma rays: observation – galaxies: starburst – galaxies: i ndividual: NGC 253 – galaxies: halos: cosmic rays

Commissioning of the new electronics and online system for the Super-Kamiokande experiment

The Super-Kamiokande (SK) detector is a ring imaging Cherenkov detector for neutrino physics and proton-decay search and consists of 50000 tons of pure water equipped with about 13000 photo-multipliers (PMTs). The old front-end electronics and online system running for more than one decade were all upgraded in September, 2008 and the data acquisition was started successfully. The new front-end electronics is based on a charge to time converter (QTC) and a multi-hit TDC. TCP/IP based readout channel is implemented to handle large amounts of data. In the new data acquisition (DAQ) scheme, the hardware event-trigger for the data reduction is replaced by processing all the hits in the online farm, so that we are able to lower the threshold of the detection energy for solar neutrino and analyze consecutive events whose time interval is too long to detect in the previous system. To make the new online system to be capable of processing larger dataflow of up to 470MB/s, we utilize Gigabit and 10Gigabit Ethernet techniques and distribute the load over Linux PCs to handle a large amount of data. In this paper, we will describe the design and performance of the new system in the commissioning.

Prototype of a Compact Imaging System for GEM Detectors

We have developed a prototype of a compact imaging system for gas electron multiplier (GEM) detectors, which we applied to thermal neutron imaging. The developed system consists of three devices: a detector, an Ethernet hub, and a PC. The readout electronics are integrated into the detector. Ethernet is used to communicate between the detector and the PC. The detector is directly connected to the PC with Ethernet. This system is simple and cost-effective, and provides high flexibility for system design. We have measured system performance and tested the system with a thermal neutron beam. This system enables use of an imaging system in various fields where it has not previously been possible to use such systems.