Abstract
We present an optically-selected cluster catalog from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The HSC images are sufficiently deep to detect cluster member galaxies down to ...M* ∼ 1010.2 M⊙ even at z ∼ 1, allowing a reliable cluster detection at such high redshifts. We apply the CAMIRA algorithm to the HSC Wide S16A dataset covering ∼232 deg2 to construct a catalog of 1921 clusters at redshift 0.1 < z < 1.1 and richness ${\skew7\hat{N}}_{\rm mem}>15$ that roughly corresponds to M200m ≳ 1014 h−1 M⊙. We confirm good cluster photometric redshift performance, with the bias and the scatter in Δz/(1 + z) being better than 0.005 and 0.01, respectively, over most of the redshift range. We compare our cluster catalog with large X-ray cluster catalogs from the XXL and XMM-LSS (the XMM Large Scale Structure) surveys and find good correlation between richness and X-ray properties.We also study the mis-centering effect from the distribution of offsets between optical and X-ray cluster centers. We confirm the high (>0.9) completeness and purity for high-mass clusters by analyzing mock galaxy catalogs.
Abstract
The Hyper Suprime-Cam (HSC) is an 870 megapixel prime focus optical imaging camera for the 8.2 m Subaru telescope. The wide-field corrector delivers sharp images of 0${^{\prime\prime}_{.}}$2 ...(FWHM) in the HSC-i band over the entire 1${^{\circ}_{.}}$5 diameter field of view. The collimation of the camera with respect to the optical axis of the primary mirror is done with hexapod actuators, the mechanical accuracy of which is a few microns. Analysis of the remaining wavefront error in off-focus stellar images reveals that the collimation of the optical components meets design specifications. While there is a flexure of mechanical components, it also is within the design specification. As a result, the camera achieves its seeing-limited imaging on Maunakea during most of the time; the median seeing over several years of observing is 0${^{\prime\prime}_{.}}$67 (FWHM) in the i band. The sensors use p-channel, fully depleted CCDs of 200 μm thickness (2048 × 4176 15 μm square pixels) and we employ 116 of them to pave the 50 cm diameter focal plane. The minimum interval between exposures is 34 s, including the time to read out arrays, to transfer data to the control computer, and to save them to the hard drive. HSC on Subaru uniquely features a combination of a large aperture, a wide field of view, sharp images and a high sensitivity especially at longer wavelengths, which makes the HSC one of the most powerful observing facilities in the world.
Diamond holds promise as a potential candidate for future particle detectors owing to its remarkable electronic, mechanical, and thermal properties. However, a notable limitation is the need for a ...comprehensive model characterizing intrinsic diamond detectors. To address this, a specialized model integrated into the technology computer‐aided design simulation program is developed. The model's validation is accomplished through its application to the evaluation of an intrinsic diamond detector. Our investigation emphasizes three key attributes: charge carrier mobility, charge carrier lifetime, and the effective charge density within the bulk material. These attributes are carefully assessed using the transient current technique. Furthermore, our model serves as a valuable tool in the analysis of the quality of an high‐pressure high‐temperature diamond crystal and in the optimization of a diamond detector's design, exploiting the charge multiplication effect. This comprehensive methodology advances our grasp of diamond detector behavior and facilitates the development of even more sophisticated devices.
Abstract
We present the luminosity function of z ∼ 4 quasars based on the Hyper Suprime-Cam Subaru Strategic Program Wide layer imaging data in the g, r, i, z, and y bands covering 339.8 deg2. From ...stellar objects, 1666 z ∼ 4 quasar candidates are selected via the g-dropout selection down to i = 24.0 mag. Their photometric redshifts cover the redshift range between 3.6 and 4.3, with an average of 3.9. In combination with the quasar sample from the Sloan Digital Sky Survey in the same redshift range, a quasar luminosity function covering the wide luminosity range of M1450 = −22 to −29 mag is constructed. The quasar luminosity function is well described by a double power-law model with a knee at M1450 = −25.36 ± 0.13 mag and a flat faint-end slope with a power-law index of −1.30 ± 0.05. The knee and faint-end slope show no clear evidence of redshift evolution from those seen at z ∼ 2. The flat slope implies that the UV luminosity density of the quasar population is dominated by the quasars around the knee, and does not support the steeper faint-end slope at higher redshifts reported at z > 5. If we convert the M1450 luminosity function to the hard X-ray 2–10 keV luminosity function using the relation between the UV and X-ray luminosity of quasars and its scatter, the number density of UV-selected quasars matches well with that of the X-ray-selected active galactic nuclei (AGNs) above the knee of the luminosity function. Below the knee, the UV-selected quasars show a deficiency compared to the hard X-ray luminosity function. The deficiency can be explained by the lack of obscured AGNs among the UV-selected quasars.
A membrane, pseudo-vertical p-i-n diamond detector Kishishita, Tetsuichi; Ichikawa, Kimiyoshi; Tauchi, Kazuya ...
Journal of nuclear science and technology,
10/2023, Letnik:
60, Številka:
10
Journal Article
Recenzirano
Odprti dostop
We report on the membrane diamond detector, which consists of 5 µm-thick p-i-n diodes and a dedicated front-end ASIC, fabricated in a 65-nm CMOS technology. The p-i-n diode has an attractive feature ...for low
-ray sensitivities due to its extremely thin drift layer, which is difficult to form by etching of bulk diamond with a Metal−Insulator−Metal structure. The pseudo-vertical p-i-n diode structure was formed on the single crystal diamond {111} substrate by MPCVD and dry-etching process. The readout electronics was designed to meet specifications for real-time neutron monitoring in harsh
-ray environments. The prototype system was evaluated in charge distribution measurements induced by
-particles from
Am. The charge spectra were successfully obtained from multi-channels, each of which has a diameter of 250 µm aligning in a pixel matrix. By combining with neutron converters, e.g.
B or
Li, we expect the detector system as a good candidate for detecting spontaneous fission neutrons, emitted from submerged fuel debris at the Fukushima Daiichi Nuclear Power Plant in Japan.
We report on the hybrid SiC pixel detector for charged-particle beam monitors in high-energy physics experiments. To demonstrate comparable performances of the state-of-the-art Si pixel detectors, ...SiC pixel sensors with a die size of 25 mm 2 were fabricated based on the p-n diode structure. We combined 12 × 12 diodes of a pixel size of 160 μm and 270 μm pitch with the dedicated readout ASIC by In/Au stud-bump technology. The front-end chip was designed in 0.35 μm CMOS technology, with consideration of a hybrid configuration. Each pixel circuit consists of a charge-sensitive amplifier and band-pass filter, optimized for the SiC sensor. The low noise performance achieved an equivalent noise charge of 55 ± 5e - (rms). The spectrum of 241 Am shows an energy resolution of 1.72 keV (FWHM) at 17.8 keV γ-rays at room temperature. The obtained image with 90 Sr is a proof of a single MIP detection capability with all pixels. Those results prospect a future application of the SiC pixel sensors to high-intensity proton extinction monitors in the COMET muon experiment at Japan Proton Accelerator Research Complex.
We report on silicon carbide (SiC) p-n junction diodes with a high blocking voltage over 3 kV. Although SiC radiation sensors have been developed with a Schottky barrier type due to a simple ...fabrication process in the early stages, p-n junction structures are advantageous due to lower sensitivity of the surface defects. Thus, this system provides an ideal condition to investigate the effect of bulk crystal defects on the characteristics of the radiation sensor. The p-n diodes were designed with a device simulator and fabricated with a 4-in 4H-SiC wafer. The epitaxial layer was grown on an n-type substrate with sufficiently low doping concentration of <inline-formula> <tex-math notation="LaTeX">{N_{\mathrm{ d}}} - {N_{\mathrm{ a}}}=\sim 5\times 10^{14} {\mathrm{ cm}}^{-3} </tex-math></inline-formula> and an average thickness of <inline-formula> <tex-math notation="LaTeX">52 ~\mu {\mathrm{ m}} </tex-math></inline-formula>. Fabricated p-n diodes with a relatively large leakage current still show a clear peak of the Landau distribution in the charge spectrum, suggesting their practical availability as minimum ionizing particle (MIP) detectors. The estimated electron-hole pair creation energy is consistent with the published studies and we expect good radiation tolerance. Feasibility based on the wafer processing indicates that the prototype devices are a good candidate for the muon beam monitor application in the COherent Muon-to-Electron Transition (COMET) experiment at Japan Proton Accelerator Research Complex (J-PARC).
We have developed an analog front-end electronics, called LTARS20181, for TPC-applications, targeted at dual-phase liquid argon TPCs for neutrino experiments and negative-ion
μ
- TPCs for directional ...dark matter searches. This electronics have a wide dynamic range for input charge up to 1600 fC and a function to output a signal with an appropriate time constant for signals having various peaking times, these unique properties may make the LTARS2018 multi-purpose. In this paper we will report results of the LTARS2018 performance check at room temperature and liquid argon temperature. In addition, we discuss the design concept and characteristics of a new electronics (LTARS2020) that been modified to improve performance in liquid argon.
We present the photometric properties of a sample of infrared (IR) bright dust-obscured galaxies (DOGs). Combining wide and deep optical images obtained with the Hyper Suprime-Cam on the Subaru ...Telescope and all-sky mid-IR (MIR) images taken with Wide-Field Infrared Survey Explorer, we discovered 48 DOGs with i − K
s > 1.2 and i − 22 > 7.0, where i, K
s, and 22 represent AB magnitude in the i-band, K
s-band, and 22 μm, respectively, in the GAMA 14 hr field (∼ 9 deg2). Among these objects, 31 (∼ 65%) show power-law spectral energy distributions (SEDs) in the near-IR (NIR) and MIR regime, while the remainder show an NIR bump in their SEDs. Assuming that the redshift distribution for our DOGs sample is Gaussian, with mean and sigma z = 1.99 ± 0.45, we calculated their total IR luminosity using an empirical relation between 22 μm luminosity and total IR luminosity. The average value of the total IR luminosity is (3.5 ± 1.1) × 1013 L⊙, which classifies them as hyper-luminous infrared galaxies. We also derived the total IR luminosity function (LF) and IR luminosity density (LD) for a flux-limited subsample of 18 DOGs with 22 μm flux greater than 3.0 mJy and with i-band magnitude brighter than 24 AB magnitude. The derived space density for this subsample is log ϕ = −6.59 ± 0.11 Mpc−3. The IR LF for DOGs including data obtained from the literature is fitted well by a double-power law. The derived lower limit for the IR LD for our sample is ρIR ∼ 3.8 × 107 L⊙ Mpc−3 and its contributions to the total IR LD, IR LD of all ultra-luminous infrared galaxies, and that of all DOGs are > 3%, > 9%, and > 15%, respectively.
Neutron imaging is one of the most powerful tools for nondestructive inspection owing to the unique characteristics of neutron beams, such as high permeability for many heavy metals, high sensitivity ...for certain light elements, and isotope selectivity owing to a specific nuclear reaction between an isotope and neutrons. In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method for the pulsed neutron source. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl<inline-formula><tex-math notation="LaTeX">_3</tex-math></inline-formula> were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the <inline-formula><tex-math notation="LaTeX">^{155}</tex-math></inline-formula>Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m × 12 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m. Gd selective imaging was performed using the resonance dip of <inline-formula><tex-math notation="LaTeX">^{155}</tex-math></inline-formula>Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.
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