The cosmic microwave background (CMB) radiation is an afterglow of the Big Bang. It contains the crucial keys to understand the beginning of the universe. In particular, the odd-parity patterns of CMB polarization, B-modes, at more than degree-scale, are the best probe to detect primordial gravitational waves at the cosmic inflation. The GroundBIRD experiment aims to detect this large angular scale patterns from the ground. The experiment employs novel techniques; a high-speed rotational scanning system (20 revolution-per-minutes) with cold optics below 4K, and microwave kinetic inductance detectors (MKIDs) as the focal plane detectors. The fast scanning modulation is a crucial characteristic in our observation strategy to mitigate effects of the atmospheric fluctuation. The telescope rotates and scans the sky along the azimuth at the elevation angle of 60 degrees at Teide observatory in the Canary Islands. It allows us to measure CMB polarization patterns at a wide multipole range, 6 < \ell < 300, i.e.
aiming to catch the reionization bump. We have developed a telescope mount with 3-axis rotation mechanism (azimuth, elevation, and boresight). We are evaluating the vibration at the focal plane position with rotating the telescope mount. The focal plane consists of seven hexagonal corrugated horn coupled MKIDs array: six hexagon units are for 145 GHz band (55 pixels/unit), and one unit is for 220 GHz band (112 pixels). Each pixel consists of a corrugated horn, a planner OMT, millimeter wave circuits for transmission of dual-polarization signals with the suppression of crosstalk modes, and two MKIDs for each polarization. Magnetic shields are also mounted so as to suppress the external magnetic fields. Trapped magnetic fields inside of the superconducting materials decrease the performance of the MKID. The geomagnetism is the static and large magnetic fields. The telescope motion makes modulation of the geomagnetism as well as the modulation of CMB signals. Therefore, we need careful evaluation associating with the telescope rotation. By using a small evaluation system with modulated magnetic fields, we understand impacts the magnetic shield as well as responses of the MKID for the modulated magnetic field. We
design the shield based on them. In this presentation, we will report an evaluation of detector responses on the high-speed rotating system along the azimuth. We will also show demonstrations of our own readout electronics which is well matching with the rapid scan modulation strategy.
We present a conceptual design to implement wide-field focal plane assembly with InGaAs image sensors which are being tested intensively and reveled to be promising for astronomical use. InGaAs image sensors are sensitive up to 1.7 microns and would open a new window for the wide-field near-infrared (NIR) imaging survey once large format sensors are developed. The sensors are not necessarily cooled down to below 100 K, which is the case for prevailing NIR image sensors such as HgCdTe, enabling us to develop the NIR camera based on the technique developed for the CCD camera in optical wavelength. The major technical challenges to employ InGaAS image sensors for wide-field NIR camera are implementation of focal plane assembly and thermal design. In this article, we discuss these difficulties and show how we can conquer based on our experience to build Hyper Suprime-Cam, which is a wide-field imager with 116 2k4k CCDs attached to Subaru Telescope.
We report the evaluation results of a commercially available InGaAs image sensor manufactured by Hamamatsu
Photonics K. K., which has sensitivity between 0.95μm and 1.7μm at a room temperature. The sensor format was
128×128 pixels with 20 μm pitch. It was tested with our original readout electronics and cooled down to 80 K by a
mechanical cooler to minimize the dark current. Although the readout noise and dark current were 200 e<sup>-</sup> and 20 e<sup>-</sup>
/sec/pixel, respectively, we found no serious problems for the linearity, wavelength response, and intra-pixel response.
Polarized patterns in the cosmic microwave background (CMB) radiation contains rich knowledge for early stage of the universe. In particular their odd-parity patterns at large angular scale (> 1°), primordial B-modes, are smoking-gun evidence for the cosmic inflation. The GroundBIRD experiment aims to detect these B-modes with a ground-based apparatus that includes several novel devices: a high-speed rotational scan system, cold optics, and microwave kinetic inductance detectors (MKIDs). We plan to start observations in the Canary Islands in 2017. In this paper, we present the status of the development of our instruments. We established an environment that allows operation of our MKIDs in an optical configuration, in which the MKIDs observe radiations from the outside of the telescope aperture. We have also constructed MKID prototypes, and we are testing them in the optical configuration.
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.
In order to explore MeV gamma-ray astronomy, we have developed the Electron Tracking Compton Camera (ETCC)
consisting of a Time projection Chamber based on the micro pixel gas counter and pixel array scintillators. By measuring the track of a recoil electron in the TPC event by event, the ETCC measures the direction of each gamma-ray, and provides both good background rejection and an angular resolution over ~1 degree. A 1m-cubic size ETCC in satellite would be a good candidate for an All sky MeV gamma-ray survey of a wide band energy region of 0.1-100MeV with several ten times better sensitivity than COMPTEL. Already we carried out a balloon experiment with a small ETCC
(Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment: SMILE-I) in 2006, and measured diffuse cosmic and
atmosphere gamma rays. We are now constructing a 30cm-cube ETCC to catch gamma-rays from the Crab and
terrestrial gamma-ray bursts at the North Pole from 2013 (SMILE-II project). Terrestrial gamma-ray bursts are generated
by relativistic electron precipitation in the Pole region. Recently performance of tracking a recoil electron has been
dramatically improved, which may enable us to reach the ideal efficiency expected for the detector. In addition, we
mention about the unique capability to find a high-z Gamma-Ray Bursts beyond z>10 by ETCC, in particular long
duration GRBs over 1000 sec, which are expected to be due to POP-III stars.
Hyper Suprime-Cam (HSC) employs 116 pieces of 2k×4k fully-depleted CCD with a total of 464 signal outputs to cover
the 1.5 degrees diameter field of view. The readout electronics was designed to achieve ~5 e of the readout noise and
150000 e of the fullwell capacity with 20 seconds readout time. Although the image size exceeds 2G Bytes, the readout
electronics supports the 10 seconds readout time for the entire CCDs continuously. All of the readout electronics and the
CCDs have already been installed in the camera dewar. The camera has been built with equipment such as coolers and an
ion pump. We report the readout performance of all channels of the electronics extracted from the recent test data.
Hyper Suprime-Cam (HSC) is the next generation wide-field imager for the prime focus of Subaru Telescope,
which is scheduled to receive its first light in 2011. Combined with a newly built wide-field corrector, HSC
covers 1.5 degree diameter field of view with 116 fully-depleted CCDs. In this presentation, we summarize the
details of the camera design: the wide-field corrector, the prime focus unit, the CCD dewar and the peripheral
devices. The wide-field corrector consists of 5 lenses with lateral shift type doublet ADC element. The novel
design guarantees the excellent image quality (D<sub>80</sub> <0".3) over the field of view. On the focal plane, 116 CCDs
are tiled on the cold plate which is made of Silicon Carbide (SiC) and cooled down to -100 degrees by two pulse
tube coolers. The system is supported by the prime focus unit which provides a precise motion of the system to
align the wide-field corrector and the CCD dewar to the optical axis of the telescope.
We develop a prototype of data analysis system for the wide-field camera Hyper Suprime-Cam (HSC) at Subaru Telescope. The current prototype is optimized for data of the current Subaru prime-focus camera Suprime-Cam, which is a precursor instrument of HSC, to study the on-site data evaluation for wide-field imaging.
The system conducts realtime data evaluation for every data frame obtaining statistical information including seeing, sky-background level, astrometric solution, and photometric zeropoint when available.
Variations in time of the derived values are shown on a web-based status monitor. The on-demand analysis such as mosaicing analysis is performed using the data evaluation results.
This system consists of analysis pipelines responsible for data processing, and the analysis organizing software for controlling analysis tasks and data flow and the database.
The XML-based database maintains all the analysis results and analysis histories. Improvement of the analysis speed by parallel data processing is achieved with the aid of the organizing software.
This system has started operation in general observations since March 2010, and will be extended to process the 104 CCD's of HSC.
The system may be used for observing support and also possible to apply to another imaging-mode instruments in the future.
Hyper Suprime-Cam (HSC) employs 116 of 2k×4k CCDs with 464 signal outputs in total. The image size
exceeds 2 GBytes, and the data can be readout every 10 seconds which results in the data rate of 210 Mbytes /
sec. The data is digitized to 16-bit. The readout noise of the electronics at the readout time of 20 seconds is
~0.9 ADU, and the one with CCD is ~1.5 ADU which corresponds to ~4.5 e. The linearity error fits within ±
0.5 % up to 150,000 e. The CCD readout electronics for HSC was newly developed based on the electronics
for Suprime-Cam. The frontend electronics (FEE) is placed in the vacuum dewar, and the backend electronics
(BEE) is mounted on the outside of the dewar on the prime focus unit. The FEE boards were designed to
minimize the outgas and to maximize the heat transfer efficiency to keep the vacuum of the dewar. The BEE
boards were designed to be simple and small as long as to achieve the readout time within 10 seconds. The
production of the system has been finished, and the full set of the boards are being tested with several CCDs
installed in the HSC dewar. We will show the system design, performance, and the current status of the
We report our activity on development of data analysis system dedicated for the Hyper Suprime-Cam (HSC),
which is a future wide-field camera at Subaru Telescope. The data analysis system (HSC-ANA) is intended for
the following achievements: (1) automated processing of an unprecedentedly huge amount of data frames without
frequent human interactions to achieve required depth and area of the key survey projects (2) immediate release
of best-effort object catalogs together with calibration information to user communities to maximize scientific
outputs. The system also enables general users to efficiently use archive data by providing appropriate meta data
describing data quality. We start with constructing a prototype data analysis system which involves minimal
functions to process data for the current prime-focus camera (Suprime-Cam). The prototype system is developed
based on combination of newly developed and existing software packages for imaging data and the framework
middleware which communicates with databases. This system is planned to help observers to perform their
observations with Suprime-Cam. Once the prototype system is evaluated, it will be scaled up to the full HSCANA
Hyper Suprime-Cam is planned to employ about 120 2k×4k fully-depleted CCDs with 4 signal outputs for each. The
data size of an image becomes larger than 2Gbytes. All of the CCDs are designed to be readout parallel within 20
seconds, and the readout noise is expected to be 5e. The frontend electronics will be mounted in a vacuumed cryostat,
and connected to the backend electronics mounted on the outside of the cryostat. The frontend electronics includes entire
analog circuits for CCD including CCD drivers, preamplifiers and ADC. The backend electronics consists of newly
developed gigabit Ethernet modules combined with 2Gbytes memory modules, and several supporting boards. We will
present the current status of the CCD readout electronics developments for HSC.
The development status of a prototype readout module for Hyper Suprime-Cam, a next-generation prime-focus camera
for the 8.2 m Subaru Telescope, is presented. The camera has a field of view 1.5° in diameter, and produces 2.1 Gbyte of
data per exposure. The module transfers the data to computers of a data acquisition system using TCP/IP and Gigabit
Ethernet. We have measured the performance of data processing and data transfer of the developed module. The results
indicated sufficient performance to read data from all CCDs within the required readout time.