32 research outputs found
2-mm-Thick Large-Area CdTe Double-sided Strip Detectors for High-Resolution Spectroscopic Imaging of X-ray and Gamma-ray with Depth-Of-Interaction Sensing
We developed a 2-mm-thick CdTe double-sided strip detector (CdTe-DSD) with a
250 um strip pitch, which has high spatial resolution with a uniform large
imaging area of 10 cm and high energy resolution with high detection
efficiency in tens to hundreds keV. The detector can be employed in a wide
variety of fields for quantitative observations of hard X-ray and soft
gamma-ray with spectroscopic imaging, for example, space observation, nuclear
medicine, and non-destructive elemental analysis. This detector is thicker than
the 0.75-mm-thick one previously developed by a factor of 2.7, thus
providing better detection efficiency for hard X-rays and soft gamma rays. The
increased thickness could potentially enhance bias-induced polarization if we
do not apply sufficient bias and if we do not operate at a low temperature, but
the polarization is not evident in our detector when a high voltage of 500 V is
applied to the CdTe diode and the temperature is maintained at -20 C
during one-day experiments. The ''Depth Of Interaction'' (DOI) dependence due
to the CdTe diode's poor carrier-transport property is also more significant,
resulting in much DOI information while complicated detector responses such as
charge sharings or low-energy tails that exacerbate the loss in the energy
resolution.
In this paper, we developed 2-mm-thick CdTe-DSDs, studied their response, and
evaluated their energy resolution, spatial resolution, and uniformity. We also
constructed a theoretical model to understand the detector response
theoretically, resulting in reconstructing the DOI with an accuracy of 100 um
while estimating the carrier-transport property. We realized the detector that
has high energy resolution and high 3D spatial resolution with a uniform large
imaging area.Comment: 13 pages, 11 figures, 1 table, Accepted for publication in NIM
The Infrared Imaging Spectrograph (IRIS) for TMT: optical design of IRIS imager with "Co-axis double TMA"
IRIS (InfraRed Imaging Spectrograph) is one of the first-generation
instruments for the Thirty Meter Telescope (TMT). IRIS is composed of a
combination of near-infrared (0.84--2.4 m) diffraction limited imager and
integral field spectrograph. To achieve near-diffraction limited resolutions in
the near-infrared wavelength region, IRIS uses the advanced adaptive optics
system NFIRAOS (Narrow Field Infrared Adaptive Optics System) and integrated
on-instrument wavefront sensors (OIWFS). However, IRIS itself has challenging
specifications. First, the overall system wavefront error should be less than
40 nm in Y, z, J, and H-band and 42 nm in K-band over a 34.0 34.0
arcsecond field of view. Second, the throughput of the imager components should
be more than 42 percent. To achieve the extremely low wavefront error and high
throughput, all reflective design has been newly proposed. We have adopted a
new design policy called "Co-Axis double-TMA", which cancels the asymmetric
aberrations generated by "collimator/TMA" and "camera/TMA" efficiently. The
latest imager design meets all specifications, and, in particular, the
wavefront error is less than 17.3 nm and throughput is more than 50.8 percent.
However, to meet the specification of wavefront error and throughput as built
performance, the IRIS imager requires both mirrors with low surface
irregularity after high-reflection coating in cryogenic and high-level Assembly
Integration and Verification (AIV). To deal with these technical challenges, we
have done the tolerance analysis and found that total pass rate is almost 99
percent in the case of gauss distribution and more than 90 percent in the case
of parabolic distribution using four compensators. We also have made an AIV
plan and feasibility check of the optical elements. In this paper, we will
present the details of this optical system.Comment: 18 pages, 14 figures, Proceeding 9908-386 of the SPIE Astronomical
Telescopes + Instrumentation 201
The Infrared Imaging Spectrograph (IRIS) for TMT: the ADC optical design
We present the current optical design for the IRIS Atmospheric Dispersion Corrector (ADC). The ADC is designed for residual dispersions less than ~1 mas across a given passband at elevations of 25 degrees. Since the last report, the area of the IRIS Imager has increased by a factor of four, and the pupil size has increased from 75 to 90mm, both of which contribute to challenges with the design. Several considerations have led to the current design: residual dispersion, amount of introduced distortion, glass transmission, glass availability, and pupil displacement. In particular, it was found that there are significant distortions that appear (two different components) that can lead to image blur over long exposures. Also, pupil displacement increases the wave front error at the imager focus. We discuss these considerations, discuss the compromises, and present the final design choice and expected performance
The Infrared Imaging Spectrograph (IRIS) for TMT: Optical design of IRIS imager with "co-axis double TMA"
IRIS (InfraRed Imaging Spectrograph) is one of the first-generation instruments for the Thirty Meter Telescope (TMT). IRIS is composed of a combination of near-infrared (0.84-2.4 μm) diffraction limited imager and integral field spectrograph. To achieve near-diffraction limited resolutions in the near-infrared wavelength region, IRIS uses the advanced adaptive optics system NFIRAOS (Narrow Field Infrared Adaptive Optics System) and integrated on-instrument wavefront sensors (OIWFS). However, IRIS itself has challenging specifications. First, the overall system wavefront error should be less than 40 nm in Y, z, J, and H-band and 42 nm in K-band over a 34.0 × 34.0 arcsecond field of view. Second, the throughput of the imager components should be more than 42 percent. To achieve the extremely low wavefront error and high throughput, all reflective design has been newly proposed. We have adopted a new design policy called "Co-Axis double-TMA", which cancels the asymmetric aberrations generated by "collimator/TMA" and "camera/TMA" efficiently. The latest imager design meets all specifications, and, in particular, the wavefront error is less than 17.3 nm and throughput is more than 50.8 percent. However, to meet the specification of wavefront error and throughput as built performance, the IRIS imager requires both mirrors with low surface irregularity after high-reflection coating in cryogenic and high-level Assembly Integration and Verification (AIV). To deal with these technical challenges, we have done the tolerance analysis and found that total pass rate is almost 99 percent in the case of gauss distribution and more than 90 percent in the case of parabolic distribution using four compensators. We also have made an AIV plan and feasibility check of the optical elements. In this paper, we will present the details of this optical syste
The Infrared Imaging Spectrograph (IRIS) for TMT: the ADC optical design
We present the current optical design for the IRIS Atmospheric Dispersion Corrector (ADC). The ADC is designed for residual dispersions less than ~1 mas across a given passband at elevations of 25 degrees. Since the last report, the area of the IRIS Imager has increased by a factor of four, and the pupil size has increased from 75 to 90mm, both of which contribute to challenges with the design. Several considerations have led to the current design: residual dispersion, amount of introduced distortion, glass transmission, glass availability, and pupil displacement. In particular, it was found that there are significant distortions that appear (two different components) that can lead to image blur over long exposures. Also, pupil displacement increases the wave front error at the imager focus. We discuss these considerations, discuss the compromises, and present the final design choice and expected performance
Insights into Land Plant Evolution Garnered from the Marchantia polymorpha Genome.
The evolution of land flora transformed the terrestrial environment. Land plants evolved from an ancestral charophycean alga from which they inherited developmental, biochemical, and cell biological attributes. Additional biochemical and physiological adaptations to land, and a life cycle with an alternation between multicellular haploid and diploid generations that facilitated efficient dispersal of desiccation tolerant spores, evolved in the ancestral land plant. We analyzed the genome of the liverwort Marchantia polymorpha, a member of a basal land plant lineage. Relative to charophycean algae, land plant genomes are characterized by genes encoding novel biochemical pathways, new phytohormone signaling pathways (notably auxin), expanded repertoires of signaling pathways, and increased diversity in some transcription factor families. Compared with other sequenced land plants, M. polymorpha exhibits low genetic redundancy in most regulatory pathways, with this portion of its genome resembling that predicted for the ancestral land plant. PAPERCLIP
熱方程式とNavier-Stokes方程式の連立系の可解性
東京理科大学201