Hard X-ray Detector Research Articles

Characteristic evaluation of a novel CdTe photon counting detector for X-ray imaging

The purpose of this paper is to investigate the characteristics of a novel cadmium-telluride (CdTe) photon counting detector optimized for X-ray imaging applications. CdTe was studied as a potential detector material for hard X-ray and gamma-ray detection. In this study, we used a CdTe photon counting detector manufactured by AJAT Ltd. (PID 350, Finland) for the purposes of both X-ray and gamma-ray detection. However, it is noted that X-ray detection can be limited by the characteristics of gamma-ray detectors. For the investigation of the characteristics of a detector for X-ray imaging, the detector has been studied in terms of detector calibration, count rate, and pixel sensitivity variation by using a poly-energetic X-ray. The detector calibration was evaluated to determine the effects of offset, gain, and energy. An optimal calibration increases the accuracy of the output energy spectrum. The pixel sensitivity variation was evaluated using profiles of various rows and columns from white (with X-ray) and dark (without X-ray) images. The specific trend of each image was observed around the edges of the hybrids. These pixel variations of the CdTe sensor were corrected. The image quality was improved by using the optimal correction method based on an understanding of the pixel sensitivity variation. The maximum recorded count rate of the detector was measured in all pixels. The count rate was measured by setting the energy windows from just above the noise level to the maximum energy. The average count rate was fairly linear up to 1.6 × 106 cps/8 modules and saturated at about 2.2 × 106 cps/8 modules. In this paper, we present several characteristics of the detector and demonstrate the improved spectrum and image obtained after calibration and correction. These results show that the novel CdTe photon counting detector can be used in conventional X-ray imaging, but exhibits limitations when applied to spectral X-ray imaging.

Suzaku Follow-Up Observation of the Activated Magnetar 1E 1547.0 5408

Abstract We present broadband X-ray analyses of the magnetar 1E 1547.0$-$ 5408 observed with Suzaku on 2010 August 7, nearly one and a half years after an intense outburst in 2009 January. The 2–10 keV flux decreased to (1.06 $ \pm$ 0.01) $ \times$ 10$ ^{-11}$ erg cm$ ^{-2}$ s$ ^{-1}$ , while the hard X-ray detection was 3.5 $ \sigma$ (18–40 keV) and 2.4 $ \sigma$ (18–35 keV) significance levels, where the former includes only the 2% systematic error of the non X-ray background, and the latter further takes into account possible near-by contaminating sources, respectively. Our confirmation of both soft and hard X-ray components during the late phase of the outburst strengthened the possibility that most magnetars are composed of the two spectral components, both in burst-active and less-active states. Together with a similar decay speed between the soft and hard components, their radiation mechanisms are suggested to be tightly related to each other. The 1–40 keV broadband spectrum was successfully fitted with the same model as used in the fit just after the onset of the outburst in 2009: a surface blackbody radiation with photoelectric absorption and a hard power-law. The blackbody flux decreased to be $ \sim$ 30% of that in 2009 while keeping its temperature at $ kT$$ =$ 0.65 keV, suggesting a shrinking hotspot on the magnetar surface by a factor of 0.3. The hard power-law extended up to at least $ \sim$ 35 keV with a photon index of $ \Gamma$$ =$ 1.1 $ \pm$ 0.4, which was consistent with the 2009 value. The flux ratio, $ \xi$ , of the 1–60 keV power-law to 1–60 keV thermal component was calculated to be $ \xi$$ =$ 1.2 $ \pm$ 0.7 at the late phase of the outburst for the first time. The obtained $ \xi$ value follows the previously known negative correlation with the characteristic age, implying that the correlation holds for most of the magnetar states: no burst, onset and late phase of outbursts.

Confirmation of the nature of the absorber in IRAS 09104+4109

We present the first long \emph{Suzaku} observation of the hyperluminous infrared galaxy IRAS 09104+4109 which is dominated by a Type 2 AGN. The infrared to X-ray SED indicates that the source is an obscured quasar with a Compton-thin absorber. However, the 3$\sigma$ hard X-ray detection of the source with the \emph{BeppoSAX} PDS suggested a reflection-dominated, Compton-thick view. The high-energy detection was later found to be possibly contaminated by another Type 2 AGN, NGC 2785, which is only 17 arcmin away. Our new \emph{Suzaku} observation offers simultaneous soft and hard X-ray coverage and excludes contamination from NGC 2785. We find that the hard X-ray component is not detected by the \emph{Suzaku} HXD/PIN (effective energy band 14-45 keV). Both reflection and transmission models have been tested on the latest \emph{Suzaku} and \emph{Chandra} data. The 0.5-10 keV spectrum can be well modelled by the two scenarios. In addition, our analysis implied that the absorption column required in both models is $N_{\rm H} \sim 5 \times 10^{23}$ cm$^{-2}$. Unless IRAS 09104+4109 is a "changing-look" quasar, we confirm that it is a Compton-thin AGN. Although the lack of detection of X-ray emission above 10 keV seems to favour the transmission scenario, we found that the two models offer fairly similar flux predictions over the X-ray band below $\sim$ 40 keV. We also found that the strong iron line shown in the \emph{Suzaku} spectrum is in fact a blend of two emission lines, in which the 6.4 keV one is mostly contributed from the AGN and the 6.7 keV from the hot cluster gas. This implies that the neutral line is perhaps caused by disc reflection, and the reflection-dominated model is more likely the explanation. The transmission model should not be completely ruled out, but a deeper hard X-ray spectrum observation is needed to discriminate between the two scenarios.

EVIDENCE OF LIGHT-BENDING EFFECTS AND ITS IMPLICATION FOR SPECTRAL STATE TRANSITIONS

It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal changes has not yet emerged. We present results from a systematic analysis of Rossi X-ray Timing Explorer observations of the stellar mass black hole binary XTE J1650-500. All spectra with significant hard X-ray detections were fit using a self-consistent, relativistically-blurred disk reflection model suited to high ionization regimes. Importantly, we find evidence that both the spectral and timing properties of black hole states may be partially driven by the height of the X-ray corona above the disk, and related changes in how gravitational light bending affects the corona--disk interaction. Specifically, the evolution of the power-law, thermal disk, and relativistically--convolved reflection components in our spectral analysis indicate that: (1) the disk inner radius remains constant at \rin$=1.65\pm0.08 GM/c^2$ (consistent with values found for the ISCO of XTE J1650-500 in other works) throughout the transition from the \textit{brighter} phases of the low-hard state to the intermediate states (both the hard-intermediate and soft-intermediate), through to the soft state and back; (2) the ratio between the observed reflected X-ray flux and power-law continuum (the "reflection fraction", R) increases sharply at the transition between the hard-intermediate and soft-intermediate states ("ballistic" jets are sometimes launched at this transition); (3) both the frequency and coherence of the high-frequency quasi-periodic oscillations (QPOs) observed in XTE J1650-500 increase with R. We discuss our results in terms of black hole states and the nature of black hole accretion flows across the mass scale.

Spectral comparison of weak short bursts to the persistent X-rays from the magnetar 1E 1547.0-5408 in its 2009 outburst

In 2009 January, the 2.1-s anomalous X-ray pulsar 1E 1547.0−5408 evoked intense burst activity. A follow-up Suzaku observation on January 28 recorded enhanced persistent emission in both soft and hard X-rays. Through a reanalysis of the same Suzaku data, 18 short bursts were identified in the X-ray events recorded by the Hard X-ray Detector (HXD) and the X-ray Imaging Spectrometer (XIS). Their spectral peaks appear in the HXD–PIN band, and their 10–70 keV X-ray fluences range from ∼2 × 10−9 to 10−7 erg cm−2. Thus, the 18 events define a significantly weaker burst sample than has ever been obtained previously, ∼10−8–10−4 erg cm−2. In the ∼0.8 to ∼300 keV band, the spectra of the three brightest bursts can be represented successfully by a two-blackbody model, or a few alternative models. A spectrum that is constructed by stacking 13 weaker short bursts with fluences in the range (0.2–2) × 10−8 erg s−1 is less curved, and its ratio to the persistent emission spectrum becomes constant at ∼170 above ∼8 keV. As a result, the two-blackbody model was able to reproduce the stacked weaker-burst spectrum only after adding a power-law model, for which the photon index is fixed at 1.54 as measured by the persistent spectrum. These results imply that there is a possibility that the spectrum composition that employs an optically thick component and a hard power-law component can describe the wide-band spectra of both the persistent and weak-burst emissions, despite the fact that their fluxes differ by two orders of magnitude. Based on the spectral similarity, we discuss a possible connection between the unresolved short bursts and the persistent emission.

PROSPECT OF STUDYING HARD X- AND GAMMA-RAYS FROM TYPE Ia SUPERNOVAE

We perform multi-dimensional, time-dependent radiation transfer simulations for hard X-ray and gamma-ray emissions, following radioactive decays of 56Ni and 56Co, for two-dimensional delayed detonation models of Type Ia supernovae (SNe Ia). The synthetic spectra and light curves are compared with the sensitivities of current and future observatories for an exposure time of 10^6 seconds. The non-detection of the gamma-ray signal from SN 2011fe at 6.4 Mpc by SPI on board INTEGRAL places an upper limit for the mass of 56Ni of \lesssim 1.0 Msun, independently from observations in any other wavelengths. Signals from the newly formed radioactive species have not been convincingly measured yet from any SN Ia, but the future X-ray and gamma-ray missions are expected to deepen the observable horizon to provide the high energy emission data for a significant SN Ia sample. We predict that the hard X-ray detectors on board NuStar (launched in 2012) or ASTRO-H (scheduled for launch in 2014) will reach to SNe Ia at \sim15 Mpc, i.e., one SN every few years. Furthermore, according to the present results, the soft gamma-ray detector on board ASTRO-H will be able to detect the 158 keV line emission up to \sim25 Mpc, i.e., a few SNe Ia per year. Proposed next generation gamma-ray missions, e.g., GRIPS, could reach to SNe Ia at \sim20 - 35 Mpc by MeV observations. Those would provide new diagnostics and strong constraints on explosion models, detecting rather directly the main energy source of supernova light.

Suzaku X-Ray Observation of the Dwarf Nova Z Camelopardalis at the Onset of an Optical Outburst

Abstract We present the result of a Suzaku X-ray spectroscopic observation of the dwarf nova Z Cam, which was conducted by chance at the onset of an optical outburst. We used the X-ray Imaging Spectrometer (a 38 ks exposure) and the Hard X-ray Detector (34 ks) to obtain a 0.35–40 keV spectrum simultaneously. Spectral characteristics suggest that the source was in the X-ray quiescent state, despite being in the rising phase of an outburst in the optical band. The spectrum shows a clear signature of circumstellar absorption in excess of interstellar absorption and the reprocessed-emission features of Fe fluorescence and Compton scattering. The extra absorption is explained as being due to partial covering by either neutral or ionized matter. We found a spectral change during the observation, which is attributable only to a change in the circumstellar absorption. Such an X-ray spectral variation was reported for the first time in the case of dwarf novae. We speculate that the variation in the circumstellar absorption is interpreted as a time-varying disk wind, or geometrically flaring disk around the white dwarf during the propagation of a heat wave along inward the accretion disk at the beginning of the outburst, in which optical outburst and X-ray quiescent states co-exist.

POSSIBLE DETECTION OF AN EMISSION CYCLOTRON RESONANCE SCATTERING FEATURE FROM THE ACCRETION-POWERED PULSAR 4U 1626–67

We present analysis of 4U 1626-67, a 7.7 s pulsar in a low-mass X-ray binary system, observed with the hard X-ray detector of the Japanese X-ray satellite Suzaku in March 2006 for a net exposure of \sim88 ks. The source was detected at an average 10-60 keV flux of \sim4 x10^-10 erg cm^-2 s^-1. The phase-averaged spectrum is reproduced well by combining a negative and positive power-law times exponential cutoff (NPEX) model modified at \sim 37 keV by a cyclotron resonance scattering feature (CRSF). The phase-resolved analysis shows that the spectra at the bright phases are well fit by the NPEX with CRSF model. On the other hand, the spectrum in the dim phase lacks the NPEX high-energy cutoff component, and the CRSF can be reproduced by either an emission or an absorption profile. When fitting the dim phase spectrum with the NPEX plus Gaussian model, we find that the feature is better described in terms of an emission rather than an absorption profile. The statistical significance of this result, evaluated by means of an F-test, is between 2.91 x 10^-3 and 1.53 x 10^-5, taking into account the systematic errors in the background evaluation of HXD-PIN. We find that, the emission profile is more feasible than the absorption one for comparing the physical parameters in other phases. Therefore, we have possibly detected an emission line at the cyclotron resonance energy in the dim phase.

Note: Measurement of the runaway electrons in the J-TEXT tokamak

The runaway electrons have been measured by hard x-ray detectors and soft x-ray array in the J-TEXT tokamak. The hard x-ray radiations in the energy ranges of 0.5-5 MeV are measured by two NaI detectors. The flux of lost runaway electrons can be obtained routinely. The soft x-ray array diagnostics are used to monitor the runaway beam generated in disruptions since the soft x-ray is dominated by the interaction between runaway electrons and metallic impurities inside the plasma. With the aid of soft x-ray array, runaway electron beam has been detected directly during the formation of runaway current plateau following the disruptions.

Improvements in Calibration of GSO Scintillators in the Suzaku Hard X-Ray Detector

Abstract Improvements of the in-orbit calibration of GSO scintillators in the Hard X-ray Detector aboard Suzaku are reported. To resolve an apparent change in the energy scale of GSO, which appeared across the launch for unknown reasons, consistent and thorough re-analyses of both pre-launch and in-orbit data have been performed. With laboratory experiments using spare hardware, the pulse-height offset, corresponding to zero energy input, was found to change by $\sim\ $ 0.5% of the full analog voltage scale, depending on the power supply. Furthermore, by carefully calculating all of the light outputs of secondaries from activation lines used in the in-orbit gain determination, their energy deposits in GSO were found to be effectively lower, by several percent, than their nominal energies. Taking both of these effects into account, the in-orbit data agree with the on-ground measurements within $\sim\ $ 5%, without employing the artificial correction introduced in previous work (Kokubun et al. 2007, PASJ, 59, S53). With this knowledge, we updated the data processing, the response, and the auxiliary files of GSO, and reproduced the HXD-PIN and HXD-GSO spectra of the Crab Nebula over 12–300 keV by a broken power-law with a break energy of $\sim\ $ 110 keV.

Onboard performance of the RT-2 detectors

The RT-2 Experiment onboard the CORONAS-PHOTON satellite is designed to study the spectral, temporal, and spatial details of solar hard X-ray flares in the 15–150 keV range. Above this energy (and upto 1000 keV), it also acts as an omni-directional gamma-ray detector with a capability to study gamma-ray bursts (GRB), bright solar flares, and X-ray pulsars. With an ensemble of hard X-ray detectors with different fields of view and coding devices, it also has the capability to investigate the spectrum of Cosmic Diffuse X-ray Background. The performance of the detectors from 2009 February to November is described in this paper. Results obtained on a few GRBs and solar flares are also briefly discussed.

Current sheath behavior and its velocity enhancement in a low energy Mather-type plasma focus device

The dynamics of the plasma sheath layer and its velocity enhancement have been studied in a low energy (4.9 kJ) Mather-type plasma focus device. Experiments were performed to study the effect of the Lorentz force variation on the current sheath expansion and movement, as well as the existence of traction between all parts of the sheath layer. Two different shape of anodes (cylindrical and step) along with an axial magnetic probe were used to investigate the effects of various experimental conditions, namely different charging voltages and gas pressures. In order to explore the upper limit of the current sheath velocity, a comparison has been made between the experimental data gathered by the probe and the Lee’s computational model. The limitations governing the enhancement of the current sheath velocity that can lead to the deterioration of a good focusing phenomenon were also investigated. The increase of the current sheath velocity due to the usage of the step anode on ion generation and hard x-ray emissions have been demonstrated by means of an ion collector and a hard x-ray detector.

THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THESWIFTBURST ALERT TELESCOPE'S EYE VIEW

The Coma Cluster of galaxies hosts the brightest radio halo known and has therefore been the target of numerous searches for associated inverse Compton (IC) emission, particularly at hard X-ray energies where the IC signal must eventually dominate over thermal emission. The most recent search with the Suzaku Hard X-ray Detector failed to confirm previous IC detections with RXTE and BeppoSAX, instead setting an upper limit 2.5 times below their non-thermal flux. However, this discrepancy can be resolved if the IC emission is very extended, beyond the scale of the cluster radio halo. Using reconstructed sky images from the 58-month Swift Burst Alert Telescope (BAT) all-sky survey, the feasibility of such a solution is investigated. Building on Renaud et al., we test and implement a method for extracting the fluxes of extended sources, assuming specified spatial distributions. BAT spectra are jointly fit with an XMM-Newton EPIC-pn spectrum derived from mosaic observations. We find no evidence for large-scale IC emission at the level expected from the previously detected non-thermal fluxes. For all non-thermal spatial distributions considered, which span the gamut of physically reasonable IC models, we determine upper limits for which the largest (most conservative) limit is ≲4.2 × 10−12 erg s−1 cm−2 (20–80 keV), which corresponds to a lower limit on the magnetic field B > 0.2 μ G. A nominal flux upper limit of <2.7 × 10−12 erg s−1 cm−2, with corresponding B > 0.25 μ G, is derived for the most probable IC distribution given the size of the radio halo and likely magnetic field radial profile.

Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation IV: background simulations using GEANT-4 toolkit

Hard X-ray detectors in space are prone to background signals due to the ubiquitous cosmic rays and cosmic diffuse background radiation that continuously bombards the satellites which carry the detectors. In general, the background intensity depends on the space environment as well as the material surrounding the detectors. Understanding the behavior of the background noise in the detector is very important to extract the precise source information from the detector data. In this paper, we carry out Monte Carlo simulations using the GEANT-4 toolkit to estimate the prompt background noise measured with the detectors of the RT-2 Experiment onboard the CORONAS-PHOTON satellite.

Low-Noise Analog ASIC for Silicon and CdTe Sensors

We report on the recent development of a 32-channel low-noise analog front-end ASIC "KW03" for hard X-ray and gamma-ray detectors. The ASIC aims for the readout of strip or pixel (pad) detectors utilizing silicon and cadmium telluride (CdTe) as detector materials. Each readout channel includes a charge-sensitive amplifier, bandpass filters and a sample-and-hold circuit. It also includes a leakage current compensation and pole-zero cancellation circuits to meet the various detector requirements. The equivalent noise level of a typical channel reaches 89 e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> @ 0 pF (rms) and shows an input-capacitance characteristic of 7.5 e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> /pF between 0 pF and 10 pF with a power consumption of 3 mW per channel. We mounted the ASIC on a low-temperature co-fired ceramic (LTCC) package and evaluated the spectral performance by combining with a CdTe diode detector. As a result, the gamma-ray spectrum of radioactive source 241 Am was obtained with a good energy resolution of 2.23 keV (FWHM) for gamma rays of 59.5 keV at -20°C.

The longest observation of a low-intensity state from a supergiant fast X-ray transient: Suzaku observes IGR J08408−4503

We report here on the longest deep X-ray observation of a SFXT outside outburst, with an average luminosity level of 1E33 erg/s (assuming 3 kpc distance). This observation was performed with Suzaku in December 2009 and was targeted on IGRJ08408-4503, with a net exposure with the X-ray imaging spectrometer (XIS, 0.4-10 keV) and the hard X-ray detector (HXD, 15-100 keV) of 67.4 ks and 64.7 ks, respectively, spanning about three days. The source was caught in a low intensity state characterized by an initially average X-ray luminosity level of 4E32 erg/s (0.5-10 keV) during the first 120 ks, followed by two long flares (about 45 ks each) peaking at a flux a factor of about 3 higher than the initial pre-flare emission. Both XIS spectra (initial emission and the two subsequent long flares) can be fitted with a double component spectrum, with a soft thermal plasma model together with a power law, differently absorbed. The spectral characteristics suggest that the source is accreting matter even at this very low intensity level. From the HXD observation we place an upper limit of 6E33 erg/s (15-40 keV; 3 kpc distance) to the hard X-ray emission, which is the most stringent constrain to the hard X-ray emission during a low intensity state in a SFXT, to date. The timescale observed for the two low intensity long flares is indicative of an orbital separation of the order of 1E13 cm in IGRJ08408-4503.

SUZAKUOBSERVATIONS OF HARD X-RAY-SELECTED SEYFERT 2 GALAXIES

We present Suzaku observations of five hard X-ray selected nearby Seyfert 2 galaxies. All the sources were clearly detected with the pin Hard X-ray Detector up to several tens of keV, allowing for a fairly good characterization of the broad-band X-ray continuum. We find that a unique model, even including multiple components, fails to represent the spectra of all the sources. Heavy obscuration manifests itself in different flavours. For two sources there is evidence for a reflection dominated continuum; among the other three, one is "mildly" Compton thick (N_H ~ 10^24 cm-2), while the remaining two are heavily obscured (N_H ~ 10^23.5 cm-2), but Compton thin. Strong, narrow, iron Kalpha lines (EW ~ 1-2 keV) due to neutral or mildly ionized gas, are detected in Compton thick AGN. In all of them the Kalpha line is accompanied by the Kbeta. The intensity and shape of the soft X-ray spectrum are different from object to object. Soft X--rays may originate from a nuclear component scattered off, or leaking through, the X-ray absorber, plus thermal X-rays from the host galaxy. Emission from circumnuclear gas photoionized by the active nucleus, parameterized with a power law plus individual narrow Gaussian lines, also provides an acceptable description of the soft X-ray spectra. The limited Suzaku XIS CCD energy resolution does not allow us to draw firm conclusions on the origin of the soft X--ray emission. We briefly discuss our findings in the light of AGN Unified model and the geometry of the obscuring gas.

WIDE-BANDSUZAKUANALYSIS OF THE PERSISTENT EMISSION FROM SGR 0501+4516 DURING THE 2008 OUTBURST

We observed the soft gamma repeater SGR 0501+4516 with Suzaku for ~51 ks on 2008 August 26-27, about 4 days after its discovery. Following the first paper, which reported on the persistent soft X-ray emission and the wide-band spectrum of an intense short burst, this paper presents an analysis of the persistent broadband (1-70 keV) spectra of this source in outburst, taken with the X-ray Imaging Spectrometer (XIS) and the Hard X-ray Detector (HXD). Pulse-phase folding in the 12-35 keV HXD-PIN data on an ephemeris based on multi-satellite timing measurements at soft X-rays revealed the pulsed signals at 99% confidence in the hard X-ray band. The wide-band spectrum clearly consists of a soft component and a separate hard component, crossing over at ~7 keV. When the soft component is modeled by a blackbody plus a Comptonized blackbody, the hard component exhibits a 20-100 keV flux of 4.8+0.8 –0.6(stat.)+0.8 –0.4(sys.) × 10–11 erg s–1 cm–2 and a photon index of Γ = 0.79+0.20 –0.18(stat.)+0.01 –0.06(sys.). The hard X-ray data are compared with those obtained by INTEGRAL about 1 day later. Combining the present results with those on other magnetars, we discuss a possible correlation between the spectral hardness of magnetars and their characteristic age and magnetic field strengths.

Hard X-ray and gamma-ray detector for ASTRO-H based on Si and CdTe imaging sensors

We have been developing a hard X-ray imager and soft gamma-ray detector as on board instruments of the ASTRO-H mission. The Hard X-ray Imager (HXI) is one of the three focal plane detectors of ASTRO-H, which is aimed to realize the focusing imaging of hard X-ray photons in combination with hard X-ray telescopes. By use of the hybrid structure composed of double-sided silicon strip detectors and a cadmium telluride strip detector, it fully covers the energy range up to 80keV with a high quantum efficiency. High spatial resolutions of 250μm pitch and energy resolutions of 1–2keV (FWMH) are at the same time achieved with low noise front-end ASICs. The Soft Gamma-ray Detector (SGD) is a novel and unique detector which is characterized by semiconductor Compton cameras surrounded by narrow field-of-view active shields, and covers a higher energy range (30–600keV) than that of HXI. It consists of four Compton Cameras constructed with many layers of Silicon and CdTe pad detectors. With its multi-layer structure and Compton reconstruction capability, in addition to the BGO active shields read by Avalanche photo-diodes, this detector will achieve an extremely high background rejection efficiency in the orbit. We report the current status of hardware development including the design requirement, expected performance, and technical readinesses of key technologies.

Study of the Large-Scale Temperature Structure of the Perseus Cluster with Suzaku

We report on a study of the large-scale temperature structure of the Perseus cluster with Suzaku, using observational data of four pointings of the 30$^{\prime}$ offset regions, together with data from the central region. Thanks to the Hard X-ray Detector (HXD-PIN: 10–60 keV), Suzaku can determine the temperature of hot galaxy clusters. We performed a spectral analysis by considering the temperature structure and the collimator response of the PIN correctly. As a result, we found that the upper limit of the temperature in the outer region is $\sim$14 keV, and an extremely hot gas, which was reported for RX J1347.5$-$1145 and Abell 3667, was not found in the Perseus cluster. This indicates that the Perseus cluster has not recently experienced a major merger.