IXPE, the first observatory dedicated to imaging x-ray polarimetry, was launched on Dec 9, 2021 and is operating successfully. A partnership between NASA and the Italian Space Agencey (ASI) IXPE features three x-ray telescopes each comprised of a mirror module assembly with a polarization sensitive detector at its focus. An extending boom was deployed on orbit to provide the necessary 4 m focal length. A three-axis-stabilized spacecraft provides power, attitude determination and control, and commanding. After one year of observation IXPE has measured statistically significant polarization from almost all the classes of celestial sources that emit X-rays. In the following we describe the IXPE mission, reporting on its performance after 1.5 year of operations. We show the main astrophysical results which are outstanding for a SMEX mission.
In this multi-messenger astronomy era, all the observational probes are improving their sensitivities and overall performance. The Focusing on Relativistic universe and Cosmic Evolution (FORCE) mission, the product of a JAXA/NASA collaboration, will reach a 10 times higher sensitivity in the hard X-ray band (E > 10 keV) in comparison with any previous hard x-ray missions, and provide simultaneous soft x-ray coverage. FORCE aims to be launched in the early 2030s, providing a perfect hard x-ray complement to the ESA flagship mission Athena. FORCE will be the most powerful x-ray probe for discovering obscured/hidden black holes and studying high energy particle acceleration in our Universe and will address how relativistic processes in the universe are realized and how these affect cosmic evolution. FORCE, which will operate over 1–79 keV, is equipped with two identical pairs of supermirrors and wideband x-ray imagers. The mirror and imager are connected by a high mechanical stiffness extensible optical bench with alignment monitor systems with a focal length of 12 m. A light-weight silicon mirror with multi-layer coating realizes a high angular resolution of < 15′′ in half-power diameter in the broad bandpass. The imager is a hybrid of a brand-new SOI-CMOS silicon-pixel detector and a CdTe detector responsible for the softer and harder energy bands, respectively. FORCE will play an essential role in the multi-messenger astronomy in the 2030s with its broadband x-ray sensitivity.
In recent years, the number of CubeSats (U-class spacecrafts) launched into space has increased exponentially marking the dawn of the nanosatellite technology. In general, these satellites have a much smaller mass budget compared to conventional scientific satellites, which limits shielding of scientific instruments against direct and indirect radiation in space. We present a simulation framework to quantify the signal in large field-of-view gamma-ray scintillation detectors of satellites induced by x-ray/gamma-ray transients, by taking into account the response of the detector. Furthermore, we quantify the signal induced by x-ray and particle background sources at a Low-Earth Orbit outside South Atlantic Anomaly and polar regions. Finally, we calculate the signal-to-noise ratio (SNR) taking into account different energy threshold levels. Our simulation can be used to optimize material composition and predict detectability of various astrophysical sources by CubeSats. We apply the developed simulation to a satellite belonging to a planned CAMELOT CubeSat constellation. This project mainly aims to detect short and long gamma-ray bursts (GRBs) and as a secondary science objective, to detect soft gamma-ray repeaters (SGRs) and terrestrial gamma-ray flashes (TGFs). The simulation includes a detailed computer-aided design model of the satellite to take into account the interaction of particles with the material of the satellite as accurately as possible. Results of our simulations predict that CubeSats can complement the large space observatories in high-energy astrophysics for observations of GRBs, SGRs, and TGFs. For the detectors planned to be on board the CAMELOT CubeSats, the simulations show that detections with SNR of at least 9 for median GRB and SGR fluxes are achievable.
This paper introduces a second-generation balloon-borne hard X-ray polarimetry mission, XL-Calibur. X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources, such as pulsars and binary black hole systems. The XL-Calibur contains a grazing incidence X-ray telescope with a focal plane detector unit that is sensitive to linear polarization. The telescope is very similar in design to the ASTRO-H HXT telescopes that has the world’s largest effective area above ~10 keV. The detector unit combines a low atomic number Compton scatterer with a CdZnTe detector assembly to measure the polarization making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation. It also contains a CdZnTe imager at the bottom. The detector assembly is surrounded by the improved anti-coincidence shielding, giving a better sensitivity. The pointing system with arcsecond accuracy will be achieved.
XL-Calibur is a balloon-borne hard X-ray polarimetry mission, the first flight of which is currently foreseen for 2021. XL-Calibur carries an X-ray telescope consists of consists of 213 Wolter I grazing-incidence mirrors which are nested in a coaxial and cofocal configuration. The optics design is nearly identical to the Hard X-ray Telescope (HXT) on board the ASTRO-H satellite. The telescope was originally fabricated for the Formation Flying Astronomical Survey Telescope (FFAST) project. However, the telescope can be used for XL-Calibur, since the FFAST project was terminated before completion. The mirror surfaces are coated with Pt/C depth-graded multilayers to reflect hard X-rays above 10 keV by Bragg reflection. The effective area of the telescope is larger than 300 cm^2 at 30 keV. The mirrors are supported by alignment bars in the housing, and each of the bars has a series of 213 grooves to hold the mirrors. To obtain the best focus of the optics, the positions of the mirrors have to be adjusted by tuning the positions of the alignment bars. The tuning of the mirror positions is conducted using the X-ray beam at the synchrotron facility SPring-8 BL20B2, and this process is called optical tuning. First the positions of the second reflectors are tuned, and then those of the first reflectors are tuned. We did the first optical tuning in Jan 2020. The second tuning will be planned between April to July, 2020. This paper reports the current status of the hard X-ray telescope for XL-Calibur.
The timing-based localization, which utilize the triangulation principle with the different arrival time of gammaray photons, with a fleet of Cubesats is a unique and powerful solution for the future all-sky gamma-ray observation, which is a key for identification of the electromagnetic counterpart of the gravitational wave sources. The Cubesats Applied for MEasuring and Localising Transients (CAMELOT) mission is now being promoted by the Hungarian and Japanese collaboration with a basic concept of the nine Cubesats constellations in low earth orbit. The simulation framework for estimation of the localization capability has been developed including orbital parameters, an algorithm to estimate the expected observed profile of gamma-ray photons, finding the peak of the cross-correlation function, and a statistical method to find a best-fit position and its uncertainty. It is revealed that a degree-scale localization uncertainty can be achieved by the CAMELOT mission concept for bright short gamma-ray bursts, which could be covered by future large field of view ground-based telescopes. The new approach utilizing machine-learning approach is also investigated to make the procedure automated for the future large scale constellations. The trained neural network with 106 simulated light curves generated by the artificial short burst templates successfully predicts the time-delay of the real light curve and achieves a comparable performance to the cross-correlation algorithm with full automated procedures.
We present the first application of a time projection chamber polarimeter to measure high energy X-ray polarization above 10 keV. The polarimeter is designed based on the PRAXyS soft X-ray polarimeter. The sealed gas is changed to a gas mixture of 60% argon and 40% dimethyl ether at 1 atm to be sensitive to high energy X-rays. The polarimeter performance is verified with linearly polarized, monochromatic X-rays at a synchrotron radiation facility, KEK Photon Factory BL-14A. The measured modulation factors are 42.4 ± 0.6%, 50.4 ± 0.6%, and 55.0 ± 0.6% at 12, 14, and 16 keV, respectively, and the measured polarization angles are consistent with the expected values at all energies.
All-sky surveys are crucial to discover transient objects. In reality, however, it is impossible to achieve high sensitivity, high cadence, wide sky coverage, and broad wavelength range at the same time. This is where observations with small telescopes can come in significant, as small telescopes often can make high cadence monitoring and flexible operations, playing a complementary role to large observatories. We plan to launch a new 6U-size CubeSat X-ray observatory, NinjaSat, in 2022 to conduct a flexible X-ray observation program. The satellite is equipped with two identical non-imaging Gas Multiplier Counters (GMCs) sensitive to X-rays in the 2–50 keV band with a total effective area of 36 cm2 at 6 keV. Coupled with X-ray collimators of a 2.1° field-of-view, NinjaSat is suitable for flexible multi-wavelength coordinated observations of bright (⪆10 mCrab) X-ray sources with particular emphasis on their time variability. An example of our targets is one of the brightest celestial X-ray objects, Scorpius X-1, which hosts a fast-spinning neutron star and is a candidate source for coherent gravitational waves. The quasi-periodic oscillation (QPO) of neutron-star systems is considered to carry important information on the neutron star’s rotational frequency, which is useful for sensitive gravitational-wave searches. Scorpius X-1, being one of the brightest, provides the best opportunity to study the QPO. Combining with coordinated simultaneous monitoring observations with recently-developed fast optical photometry, the mechanism of the mass accretion of the disk can also be studied. We plan to use NinjaSat also for space science education, particularly X-ray astronomy, for students and the general public.
The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to the 2016 Hitomi mission that ended prematurely. Like Hitomi, the primary science goals are to examine astrophysical problems with precise highresolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. XRISM carries a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly and a co-aligned X-ray CCD camera that covers the same energy band over a large field of view. XRISM utilizes Hitomi heritage, but all designs were reviewed. The attitude and orbit control system were improved in hardware and software. The number of star sensors were increased from two to three to improve coverage and robustness in onboard attitude determination and to obtain a wider field of view sun sensor. The fault detection, isolation, and reconfiguration (FDIR) system was carefully examined and reconfigured. Together with a planned increase of ground support stations, the survivability of the spacecraft is significantly improved.
HiZ-GUNDAM is a future satellite mission which will lead the time-domain astronomy and the multi-messenger astronomy through observations of high-energy transient phenomena. A mission concept of HiZ-GUNDAM was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s medium-class mission. We are in pre-phase A (before pre-project) and elaborating the mission concept, mission/system requirements for the launch in the late 2020s. The main themes of HiZ-GUNDAM mission are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy. HiZ-GUNDAM has two kinds of mission payload. The wide field X-ray monitors consist of Lobster Eye optics array and focal imaging sensor, and monitor ~1 steradian field of view in 0.5 – 4 keV energy range. The near infrared telescope has an aperture size 30 cm in diameter, and simultaneously observes four wavelength bands between 0.5 – 2.5 μm. In this paper, we introduce the mission overview of HiZ-GUNDAM.
GRBAlpha is a 1U CubeSat mission with an expected launch date in the first half of 2021. It carries a 75 × 75 × 5 mm CsI(Tl) scintillator, read out by a dual-channel multi-pixel photon counter (MPPC) setup, to detect gamma-ray bursts (GRBs). The GRB detector is an in-orbit demonstration for the detector system on the Cubesats Applied for MEasuring and LOcalising Transients (CAMELOT) mission. While GRBAlpha provides 1/8th of the expected effective area of CAMELOT, the comparison of the observed light curves with other existing GRB monitoring satellites will allow us to validate the core idea of CAMELOT, i.e. the feasibility of timing-based localization
The XRISM X-ray observatory will fly two advanced instruments, the Resolve high-resolution spectrometer and the Xtend wide-field imager. These instruments, particularly Resolve, pose calibration challenges due to the unprecedented combination of spectral resolution, spectral coverage, and effective area, combined with a need to characterize the imaging fidelity of the full instrument system to realize the mission’s ambitious science goals. We present the status of the XRISM in-flight calibration plan, building on lessons from Hitomi and other X-ray missions. We present a discussion of targets and observing strategies to address the needed calibration measurements, with a focus on developing methodologies to plan a thorough and flexible calibration campaign and provide insight on calibration systematic error. We also discuss observations that exploit Resolve’s spectral
Understanding and reducing in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard x-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic numbers: the HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of cadmium telluride (CdTe) (Z = 48, 52) detector surrounded by well-type Bi4Ge3O12 active shields. Based on the observational data, the backgrounds of the top Si layer, the three underlying Si layers, and the CdTe layer are inferred to be dominated by different components, namely, low-energy electrons, albedo neutrons, and proton-induced radioactivation, respectively. Monte Carlo simulations of the in-orbit background of the HXI reproduce the observed background spectrum of each layer well, thereby quantitatively verifying the above hypothesis. In addition, we suggest the inclusion of an electron shield to reduce the background.
We propose a concept of multiplexing lobster-eye (MuLE) optics to achieve significant reductions in the number of focal plane imagers in lobster-eye (LE) wide-field x-ray monitors. In the MuLE configuration, an LE mirror is divided into several segments and the x-rays reflected on each of these segments are focused on a single image sensor in a multiplexed configuration. If each LE segment assumes a different rotation angle, the azimuthal rotation angle of a cross-like image reconstructed from a point source by the LE optics identifies the specific segment that focuses the x-rays on the imager. With a focal length of 30 cm and LE segments with areas of 10 × 10 cm2, ∼1 sr of the sky can be covered with 36 LE segments and only four imagers (with total areas of 10 × 10 cm2). A ray tracing simulation was performed to evaluate the nine-segment MuLE configuration. The simulation showed that the flux (0.5 to 2 keV) associated with the 5σ detection limit was ∼2 × 10 − 10 erg cm − 2 s − 1 (10 mCrab) for a transient with a duration of 100 s. The simulation also showed that the direction of the transient for flux in the range of 14 to 17 mCrab at 0.6 keV was determined correctly with a 99.7% confidence limit. We conclude that the MuLE configuration can become an effective on-board device for small satellites for future x-ray wide-field transient monitoring.
NASA's Neutron star Interior Composition Explorer (NICER) progressed smoothly through its final ground-test activities in 2016 and early 2017, in preparation for a spectacular launch and installation on the International Space Station in June 2017. Activation of the payload and initial calibration of its systems followed, rounding out Phase D, Testing and Commissioning, of the mission's development cycle. We describe the final ground verification measurements of NICER's key performance parameters, such as the X-ray Timing Instrument's photon energy resolution and time-stamping accuracy, as well as in-flight effective collecting area, pointing, background, and other calibration efforts. The payload meets all of its design requirements and is poised to deliver new insights in soft X-ray astrophysics; briefly, we touch on early science returns that showcase NICER's unique capabilities.
A fleet of nanosatellites using precise timing synchronization provided by the Global Positioning System is a new concept for monitoring the gamma-ray sky that can achieve both all-sky coverage and good localization accuracy. We are proposing this new concept for the mission CubeSats Applied for MEasuring and LOcalising Transients (CAMELOT). The differences in photon arrival times at each satellite are to be used for source localization. Detectors with good photon statistics and the development of a localization algorithm capable of handling a large number of satellites are both essential for this mission. Large, thin CsI scintillator plates are the current candidates for the detectors because of their high light yields. It is challenging to maximize the light-collection efficiency and to understand the position dependence of such thin plates. We have found a multi-channel readout that uses the coincidence technique to be very effective in increasing the light output while keeping a similar noise level to that of a single channel readout. Based on such a detector design, we have developed a localization algorithm for this mission and have found that we can achieve a localization accuracy better than 20 arc minutes and a rate of about 10 short gamma-ray bursts per year.
We propose a fleet of nanosatellites to perform an all-sky monitoring and timing based localisation of gamma-ray transients. The fleet of at least nine 3U cubesats shall be equipped with large and thin CsI(Tl) scintillator based soft gamma-ray detectors read out by multi-pixel photon counters. For bright short gamma-ray bursts (GRBs), by cross-correlating their light curves, the fleet shall be able to determine the time difference of the arriving GRB signal between the satellites and thus determine the source position with an accuracy of ∼ 100 . This requirement demands precise time synchronization and accurate time stamping of the detected gamma-ray photons, which will be achieved by using on-board GPS receivers. Rapid follow up observations at other wavelengths require the capability for fast, nearly simultaneous downlink of data using a global inter-satellite communication network. In terms of all-sky coverage, the proposed fleet will outperform all GRB monitoring missions.
The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi,“Resolving astrophysical problems by precise high-resolution X-ray spectroscopy”.1 This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission’s initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020’s and 2030’s. Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: “Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects”. To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 × 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.
Hitomi (ASTRO-H) was the sixth Japanese x-ray satellite that carried instruments with exquisite energy resolution of <7 eV and broad energy coverage of 0.3 to 600 keV. The Soft Gamma-ray Detector (SGD) was the Hitomi instrument that observed the highest energy band (60 to 600 keV). The SGD design achieves a low background level by combining active shields and Compton cameras where Compton kinematics is utilized to reject backgrounds coming from outside of the field of view. A compact and highly efficient Compton camera is realized using a combination of silicon and cadmium telluride semiconductor sensors with a good energy resolution. Compton kinematics also carries information for gamma-ray polarization, making the SGD an excellent polarimeter. Following several years of development, the satellite was successfully launched on February 17, 2016. After proper functionality of the SGD components were verified, the nominal observation mode was initiated on March 24, 2016. The SGD observed the Crab Nebula for approximately two hours before the spacecraft ceased to function on March 26, 2016. We present concepts of the SGD design followed by detailed description of the instrument and its performance measured on ground and in orbit.
The hard x-ray imaging spectroscopy system of “Hitomi” x-ray observatory is composed of two sets of hard x-ray imagers (HXI) coupled with hard x-ray telescopes (HXT). With a 12-m focal length, the system provides fine (1 ′ . 7 half-power diameter) imaging spectroscopy covering about 5 to 80 keV. The HXI sensor consists of a camera, which is composed of four layers of Si and one layer of CdTe semiconductor imagers, and an active shield composed of nine Bi4Ge3O12 scintillators to provide low background. The two HXIs started observation on March 8 and 14, 2016 and were operational until 26 March. Using a Crab observation, 5 to 80 keV energy coverage and good detection efficiency were confirmed. The detector background level of 1 to 3 × 10 − 4 counts s − 1 keV − 1 cm − 2 (in detector geometrical area) at 5 to 80 keV was achieved, by cutting the high-background time-intervals, adopting sophisticated energy-dependent imager layer selection, and baffling of the cosmic x-ray background and active-shielding. This level is among the lowest of detectors working in this energy band. By comparing the effective area and the background, it was shown that the HXI had a sensitivity that is same to that of NuSTAR for point sources and 3 to 4 times better for largely extended diffuse sources.
The Hard X-ray Imager (HXI) onboard Hitomi (ASTRO-H) is an imaging spectrometer covering hard x-ray energies of 5 to 80 keV. Combined with the Hard X-ray Telescope, it enables imaging spectroscopy with an angular resolution of 1′.7 half-power diameter, in a field of view of 9′ × 9′. The main imager is composed of four layers of Si detectors and one layer of CdTe detector, stacked to cover a wide energy band up to 80 keV, surrounded by an active shield made of Bi4Ge3O12 scintillator to reduce the background. The HXI started observations 12 days before the Hitomi loss and successfully obtained data from G21.5–0.9, Crab, and blank sky. Utilizing these data, we calibrate the detector response and study properties of in-orbit background. The observed Crab spectra agree well with a powerlaw model convolved with the detector response, within 5% accuracy. We find that albedo electrons in specified orbit strongly affect the background of the Si top layer and establish a screening method to reduce it. The background level over the full field of view after all the processing and screening is as low as the preflight requirement of 1 − 3 × 10−4 counts s−1 cm−2 keV−1.
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
P. Soffitta, R. Bellazzini, E. Bozzo, V. Burwitz, A. Castro-Tirado, E. Costa, T. Courvoisier, H. Feng, S. Gburek, R. Goosmann, V. Karas, G. Matt, F. Muleri, K. Nandra, M. Pearce, J. Poutanen, V. Reglero, D. Sabau Maria, A. Santangelo, G. Tagliaferri, C. Tenzer, J. Vink, M. Weisskopf, S. Zane, I. Agudo, A. Antonelli, P. Attina, L. Baldini, A. Bykov, R. Carpentiero, E. Cavazzuti, E. Churazov, E. Del Monte, D. De Martino, I. Donnarumma, V. Doroshenko, Y. Evangelista, I. Ferreira, E. Gallo, N. Grosso, P. Kaaret, E. Kuulkers, J. Laranaga, L. Latronico, D. Lumb, J. Macian, J. Malzac, F. Marin, E. Massaro, M. Minuti, C. Mundell, J. U. Ness, T. Oosterbroek, S. Paltani, G. Pareschi, R. Perna, P.-O. Petrucci, H. B. Pinazo, M. Pinchera, J. P. Rodriguez, M. Roncadelli, A. Santovincenzo, S. Sazonov, C. Sgro, D. Spiga, J. Svoboda, C. Theobald, T. Theodorou, R. Turolla, E. Wilhelmi de Ona, B. Winter, A. M. Akbar, H. Allan, R. Aloisio, D. Altamirano, L. Amati, E. Amato, E. Angelakis, J. Arezu, J.-L. Atteia, M. Axelsson, M. Bachetti, L. Ballo, S. Balman, R. Bandiera, X. Barcons, S. Basso, A. Baykal, W. Becker, E. Behar, B. Beheshtipour, R. Belmont, E. Berger, F. Bernardini, S. Bianchi, G. Bisnovatyi-Kogan, P. Blasi, P. Blay, A. Bodaghee, M. Boer, M. Boettcher, S. Bogdanov, I. Bombaci, R. Bonino, J. Braga, W. Brandt, A. Brez, N. Bucciantini, L. Burderi, I. Caiazzo, R. Campana, S. Campana, F. Capitanio, M. Cappi, M. Cardillo, P. Casella, O. Catmabacak, B. Cenko, P. Cerda-Duran, C. Cerruti, S. Chaty, M. Chauvin, Y. Chen, J. Chenevez, M. Chernyakova, C. C. Cheung, D. Christodoulou, P. Connell, R. Corbet, F. Coti Zelati, S. Covino, W. Cui, G. Cusumano, A. D’Ai, F. D’Ammando, M. Dadina, Z. Dai, A. De Rosa, L. de Ruvo, N. Degenaar, M. Del Santo, L. Del Zanna, G. Dewangan, S. Di Cosimo, N. Di Lalla, G. Di Persio, T. Di Salvo, T. Dias, C. Done, M. Dovciak, G. Doyle, L. Ducci, R. Elsner, T. Enoto, J. Escada, P. Esposito, C. Eyles, S. Fabiani, M. Falanga, S. Falocco, Y. Fan, R. Fender, M. Feroci, C. Ferrigno, W. Forman, L. Foschini, C. Fragile, F. Fuerst, Y. Fujita, J. L. Gasent-Blesa, J. Gelfand, B. Gendre, G. Ghirlanda, G. Ghisellini, M. Giroletti, D. Goetz, E. Gogus, J.-L. Gomez, D. Gonzalez, R. Gonzalez-Riestra, E. Gotthelf, L. Gou, P. Grandi, V. Grinberg, F. Grise, C. Guidorzi, N. Gurlebeck, T. Guver, D. Haggard, M. Hardcastle, D. Hartmann, C. Haswell, A. Heger, M. Hernanz, J. Heyl, L. Ho, J. Hoormann, J. Horak, J. Huovelin, D. Huppenkothen, R. Iaria, C. Inam Sitki, A. Ingram, G. Israel, L. Izzo, M. Burgess, M. Jackson, L. Ji, J. Jiang, T. Johannsen, C. Jones, S. Jorstad, J. J. E. Kajava, M. Kalamkar, E. Kalemci, T. Kallman, A. Kamble, F. Kislat, M. Kiss, D. Klochkov, E. Koerding, M. Kolehmainen, K. Koljonen, S. Komossa, A. Kong, S. Korpela, M. Kowalinski, H. Krawczynski, I. Kreykenbohm, M. Kuss, D. Lai, M. Lan, J. Larsson, S. Laycock, D. Lazzati, D. Leahy, H. Li, J. Li, L.-X. Li, T. Li, Z. Li, M. Linares, M. Lister, H. Liu, G. Lodato, A. Lohfink, F. Longo, G. Luna, A. Lutovinov, S. Mahmoodifar, J. Maia, V. Mainieri, C. Maitra, D. Maitra, A. Majczyna, S. Maldera, D. Malyshev, A. Manfreda, A. Manousakis, R. Manuel, R. Margutti, A. Marinucci, S. Markoff, A. Marscher, H. Marshall, F. Massaro, M. McLaughlin, G. Medina-Tanco, M. Mehdipour, M. Middleton, R. Mignani, P. Mimica, T. Mineo, B. Mingo, G. Miniutti, S. M. Mirac, G. Morlino, A. Motlagh, S. Motta, A. Mushtukov, S. Nagataki, F. Nardini, J. Nattila, G. Navarro, B. Negri, Matteo Negro, S. Nenonen, V. Neustroev, F. Nicastro, A. Norton, A. Nucita, P. O’Brien, S. O’Dell, H. Odaka, B. Olmi, N. Omodei, M. Orienti, M. Orlandini, J. Osborne, L. Pacciani, V. Paliya, I. Papadakis, A. Papitto, Z. Paragi, P. Pascal, B. Paul, L. Pavan, A. Pellizzoni, E. Perinati, M. Pesce-Rollins, E. Piconcelli, A. Pili, M. Pilia, M. Pohl, G. Ponti, D. Porquet, A. Possenti, K. Postnov, I. Prandoni, N. Produit, G. Puehlhofer, B. Ramsey, M. Razzano, N. Rea, P. Reig, K. Reinsch, T. Reiprich, M. Reynolds, G. Risaliti, T. Roberts, J. Rodriguez, M. Rossi, S. Rosswog, A. Rozanska, A. Rubini, B. Rudak, D. Russell, F. Ryde, S. Sabatini, G. Sala, M. Salvati, M. Sasaki, T. Savolainen, R. Saxton, S. Scaringi, K. Schawinski, N. Schulz, A. Schwope, P. Severgnini, M. Sharon, A Shaw, A. Shearer, X. Shesheng, I. -C. Shih, K. Silva, R. Silva, E. Silver, A. Smale, F. Spada, G. Spandre, A. Stamerra, B. Stappers, S. Starrfield, L. Stawarz, N. Stergioulas, A. Stevens, H. Stiele, V. Suleimanov, R. Sunyaev, A. Slowikowska, F. Tamborra, F. Tavecchio, R. Taverna, A. Tiengo, L. Tolos, F. Tombesi, J. Tomsick, H. Tong, G. Torok, D. Torres, A. Tortosa, A. Tramacere, V. Trimble, G. Trinchieri, S. Tsygankov, M. Tuerler, S. Turriziani, F. Ursini, P. Uttley, P. Varniere, F. Vincent, E. Vurgun, C. Wang, Z. Wang, A. Watts, J. Wheeler, K. Wiersema, R. Wijnands, J. Wilms, A. Wolter, K. Wood, K. Wu, X. Wu, W. Xiangyu, F. Xie, R. Xu, S.-P. Yan, J. Yang, W. Yu, F. Yuan, A. Zajczyk, D. Zanetti, R. Zanin, C. Zanni, L. Zappacosta, A. Zdziarski, A. Zech, H. Zhang, S. Zhang, W. Zhang, A. Zoghbi
XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of
writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the
polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently
exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially-
resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics.
Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective
area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega
launcher. XIPE is designed as an observatory for X-ray astronomers with 75 % of the time dedicated to a Guest
Observer competitive program and it is organized as a consortium across Europe with main contributions from
Italy, Germany, Spain, United Kingdom, Poland, Sweden.
Hitomi X-ray observatory launched in 17 February 2016 had a hard X-ray imaging spectroscopy system made of two hard X-ray imagers (HXIs) coupled with two hard X-ray telescopes (HXTs). With 12 m focal length, they provide fine (2' half-power diameter; HPD) imaging spectroscopy at 5 to 80 keV. The HXI main imagers are made of 4 layers of Si and a CdTe semiconductor double-sided strip detectors, stacked to enhance detection efficiency as well as to enable photon interaction-depth sensing. Active shield made of 9 BGO scintillators surrounds the imager to provide with low background. Following the deployment of the Extensible Optical Bench (EOB) on 28 February, the HXI was gradually turned on. Two imagers successfully started observation on 14 March, and was operational till the incident lead to Hitomo loss, on 26 March. All detector channels, 1280 ch of imager and 11 channel of active shields and others each, worked well and showed performance consistent with those seen on ground. From the first light observation of G21.5-0.9 and the following Crab observations, 5-80 keV energy coverage and good detection efficiency were confirmed. With blank sky observations, we checked our background level. In some geomagnetic region, strong background continuum, presumably caused by trapped electron with energy ~100 keV, is seen. But by cutting the high-background time-intervals, the background became significantly lower, typically with 1-3 x 10-4 counts s-1 keV-1 cm-2 (here cm2 is shown with detector geometrical area). Above 30 keV, line and continuum emission originating from activation of CdTe was significantly seen, though the level of 1-4 x 10-4 counts s-1 keV-1 cm-2 is still comparable to those seen in NuSTAR. By comparing the effective area and background rate, preliminary analysis shows that the HXI had a statistical sensitivity similar to NuSTAR for point sources, and more than twice better for largely extended sources.
KEYWORDS: X-rays, Solar concentrators, Sensors, X-ray detectors, Aerospace engineering, Analog electronics, Mathematical modeling, Device simulation, Signal detection, Space telescopes
Neutron star Interior Composition ExploreR (NICER) is a NASA instrument to be onboard International Space Station, which is equipped with 56 pairs of an X-ray concentrator (XRC) and a silicon drift detector for high timing observations. The XRC is based on an epoxy replicated thin aluminum foil X-ray mirror, similar to those of Suzaku and ASTRO-H (Hitomi), but only a single stage parabolic grazing incidence optic. Each has a focal length of 1.085m and a diameter of 105 mm, with 24 confocally aligned parabolic shells. Grazing incident angles to individual shells range from 0.4 to 1.4 deg. The flight 56 XRCs have been completed and successfully delivered to the payload integration. All the XRC was characterized at the NASA/GSFC 100-m X-ray beamline using 1.5 keV X-rays (some of them are also at 4.5 keV). The XRC performance, effective area and point spread function, was measured by a CCD camera and a proportional counter. The average effective area is about 44 cm2 at 1.5 keV and about 18 cm2 at 4.5 keV, which is consistent with a micro-roughness of 0.5nm from individual shell reflectivity measurements. The XRC focuses about 91% of X-rays into a 2mm aperture at the focal plane, which is the NICER detector window size. Each XRC weighs only 325 g. These performance met the project requirement. In this paper, we will present summary of the flight XRC performance as well as co-alignment results of the 56 XRCs on the flight payload as it is important to estimate the total effective for astronomical observations.
M. Feroci, E. Bozzo, S. Brandt, M. Hernanz, M. van der Klis, L.-P. Liu, P. Orleanski, M. Pohl, A. Santangelo, S. Schanne, L. Stella, T. Takahashi, H. Tamura, A. Watts, J. Wilms, S. Zane, S.-N. Zhang, S. Bhattacharyya, I. Agudo, M. Ahangarianabhari, C. Albertus, M. Alford, A. Alpar, D. Altamirano, L. Alvarez, L. Amati, C. Amoros, N. Andersson, A. Antonelli, A. Argan, R. Artigue, B. Artigues, J.-L. Atteia, P. Azzarello, P. Bakala, D. Ballantyne, G. Baldazzi, M. Baldo, S. Balman, M. Barbera, C. van Baren, D. Barret, A. Baykal, M. Begelman, E. Behar, O. Behar, T. Belloni, F. Bernardini, G. Bertuccio, S. Bianchi, A. Bianchini, P. Binko, P. Blay, F. Bocchino, M. Bode, P. Bodin, I. Bombaci, J.-M. Bonnet Bidaud, S. Boutloukos, F. Bouyjou, L. Bradley, J. Braga, M. Briggs, E. Brown, M. Buballa, N. Bucciantini, L. Burderi, M. Burgay, M. Bursa, C. Budtz-Jørgensen, E. Cackett, F. Cadoux, P. Cais, G. Caliandro, R. Campana, S. Campana, X. Cao, F. Capitanio, J. Casares, P. Casella, A. Castro-Tirado, E. Cavazzuti, Y. Cavechi, S. Celestin, P. Cerda-Duran, D. Chakrabarty, N. Chamel, F. Château, C. Chen, Y. Chen, J. Chenevez, M. Chernyakova, J. Coker, R. Cole, A. Collura, M. Coriat, R. Cornelisse, L. Costamante, A. Cros, W. Cui, A. Cumming, G. Cusumano, B. Czerny, A. D'Aì, F. D'Ammando, V. D'Elia, Z. Dai, E. Del Monte, A. De Luca, D. De Martino, J. P. C. Dercksen, M. De Pasquale, A. De Rosa, M. Del Santo, S. Di Cosimo, N. Degenaar, J. W. den Herder, S. Diebold, T. Di Salvo, Y. Dong, I. Donnarumma, V. Doroshenko, G. Doyle, S. Drake, M. Durant, D. Emmanoulopoulos, T. Enoto, M. H. Erkut, P. Esposito, Y. Evangelista, A. Fabian, M. Falanga, Y. Favre, C. Feldman, R. Fender, H. Feng, V. Ferrari, C. Ferrigno, M. Finger, G. Fraser, M. Frericks, M. Fullekrug, F. Fuschino, M. Gabler, D. K. Galloway, J. L. Gálvez Sanchez, P. Gandhi, Z. Gao, E. Garcia-Berro, B. Gendre, O. Gevin, S. Gezari, A. B. Giles, M. Gilfanov, P. Giommi, G. Giovannini, M. Giroletti, E. Gogus, A. Goldwurm, K. Goluchová, D. Götz, L. Gou, C. Gouiffes, P. Grandi, M. Grassi, J. Greiner, V. Grinberg, P. Groot, M. Gschwender, L. Gualtieri, M. Guedel, C. Guidorzi, L. Guy, D. Haas, P. Haensel, M. Hailey, K. Hamuguchi, F. Hansen, D. Hartmann, C. A. Haswell, K. Hebeler, A. Heger, M. Hempel, W. Hermsen, J. Homan, A. Hornstrup, R. Hudec, J. Huovelin, D. Huppenkothen, S. Inam, A. Ingram, J. In't Zand, G. Israel, K. Iwasawa, L. Izzo, H. Jacobs, F. Jetter, T. Johannsen, P. Jenke, P. Jonker, J. Josè, P. Kaaret, K. Kalamkar, E. Kalemci, G. Kanbach, V. Karas, D. Karelin, D. Kataria, L. Keek, T. Kennedy, D. Klochkov, W. Kluzniak, E. Koerding, K. Kokkotas, S. Komossa, S. Korpela, C. Kouveliotou, A. Kowalski, I. Kreykenbohm, L. Kuiper, D. Kunneriath, A. Kurkela, I. Kuvvetli, F. La Franca, C. Labanti, D. Lai, F. Lamb, C. Lachaud, P. Laubert, F. Lebrun, X. Li, E. Liang, O. Limousin, D. Lin, M. Linares, D. Linder, G. Lodato, F. Longo, F. Lu, N. Lund, T. Maccarone, D. Macera, S. Maestre, S. Mahmoodifar, D. Maier, P. Malcovati, J. Malzac, C. Malone, I. Mandel, V. Mangano, A. Manousakis, M. Marelli, J. Margueron, M. Marisaldi, S. Markoff, A. Markowitz, A. Marinucci, A. Martindale, G. Martínez, I. McHardy, G. Medina-Tanco, M. Mehdipour, A. Melatos, M. Mendez, S. Mereghetti, S. Migliari, R. Mignani, M. Michalska, T. Mihara, M. C. Miller, J. M. Miller, T. Mineo, G. Miniutti, S. Morsink, C. Motch, S. Motta, M. Mouchet, G. Mouret, J. Mulačová, F. Muleri, T. Muñoz-Darias, I. Negueruela, J. Neilsen, T. Neubert, A. Norton, M. Nowak, A. Nucita, P. O'Brien, M. Oertel, P. E. H. Olsen, M. Orienti, M. Orio, M. Orlandini, J. Osborne, R. Osten, F. Ozel, L. Pacciani, F. Paerels, S. Paltani, M. Paolillo, I. Papadakis, A. Papitto, Z. Paragi, J. Paredes, A. Patruno, B. Paul, F. Pederiva, E. Perinati, A. Pellizzoni, A. V. Penacchioni, U. Peretz, M. Perez, M. Perez-Torres, B. Peterson, V. Petracek, C. Pittori, J. Pons, J. Portell, A. Possenti, K. Postnov, J. Poutanen, M. Prakash, I. Prandoni, H. Le Provost, D. Psaltis, J. Pye, J. Qu, D. Rambaud, P. Ramon, G. Ramsay, M. Rapisarda, A. Rashevski, I. Rashevskaya, P. Ray, N. Rea, S. Reddy, P. Reig, M. Reina Aranda, R. Remillard, C. Reynolds, L. Rezzolla, M. Ribo, R. de la Rie, A. Riggio, A. Rios, D. Rischke, P. Rodríguez-Gil, J. Rodriguez, R. Rohlfs, P. Romano, E. M. Rossi, A. Rozanska, A. Rousseau, B. Rudak, D. Russell, F. Ryde, L. Sabau-Graziati, T. Sakamoto, G. Sala, R. Salvaterra, D. Salvetti, A. Sanna, J. Sandberg, T. Savolainen, S. Scaringi, J. Schaffner-Bielich, H. Schatz, J. Schee, C. Schmid, M. Serino, N. Shakura, S. Shore, J. Schnittman, R. Schneider, A. Schwenk, A. Schwope, A. Sedrakian, J.-Y. Seyler, A. Shearer, A. Slowikowska, M. Sims, A. Smith, D. Smith, P. Smith, M. Sobolewska, V. Sochora, P. Soffitta, P. Soleri, L. Song, A. Spencer, A. Stamerra, B. Stappers, R. Staubert, A. Steiner, N. Stergioulas, A. Stevens, G. Stratta, T. Strohmayer, Z. Stuchlik, S. Suchy, V. Suleimanov, F. Tamburini, T. Tauris, F. Tavecchio, C. Tenzer, F. Thielemann, A. Tiengo, L. Tolos, F. Tombesi, J. Tomsick, G. Torok, J. M. Torrejon, D. F. Torres, E. Torresi, A. Tramacere, I. Traulsen, A. Trois, R. Turolla, S. Turriziani, S. Typel, P. Uter, P. Uttley, A. Vacchi, P. Varniere, S. Vaughan, S. Vercellone, M. Vietri, F. Vincent, V. Vrba, D. Walton, J. Wang, Z. Wang, S. Watanabe, R. Wawrzaszek, N. Webb, N. Weinberg, H. Wende, P. Wheatley, R. Wijers, R. Wijnands, M. Wille, C. Wilson-Hodge, B. Winter, S. Walk, K. Wood, S. Woosley, X. Wu, R. Xu, W. Yu, F. Yuan, W. Yuan, Y. Yuan, G. Zampa, N. Zampa, L. Zampieri, L. Zdunik, A. Zdziarski, A. Zech, B. Zhang, C. Zhang, S. Zhang, M. Zingale, F. Zwart
The Large Observatory For x-ray Timing (LOFT) is a mission concept which was proposed to ESA as M3 and M4 candidate in the framework of the Cosmic Vision 2015-2025 program. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument and the uniquely large field of view of its wide field monitor, LOFT will be able to study the behaviour of matter in extreme conditions such as the strong gravitational field in the innermost regions close to black holes and neutron stars and the supra-nuclear densities in the interiors of neutron stars. The science payload is based on a Large Area Detector (LAD, >8m2 effective area, 2-30 keV, 240 eV spectral resolution, 1 degree collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g., GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the current technical and programmatic status of the mission.
Keith Gendreau, Zaven Arzoumanian, Phillip Adkins, Cheryl Albert, John Anders, Andrew Aylward, Charles Baker, Erin Balsamo, William Bamford, Suyog Benegalrao, Daniel Berry, Shiraz Bhalwani, J. Kevin Black, Carl Blaurock, Ginger Bronke, Gary Brown, Jason Budinoff, Jeffrey Cantwell, Thoniel Cazeau, Philip Chen, Thomas Clement, Andrew Colangelo, Jerry Coleman, Jonathan Coopersmith, William Dehaven, John Doty, Mark Egan, Teruaki Enoto, Terry Fan, Deneen Ferro, Richard Foster, Nicholas Galassi, Luis Gallo, Chris Green, Dave Grosh, Kong Ha, Monther Hasouneh, Kristofer Heefner, Phyllis Hestnes, Lisa Hoge, Tawanda Jacobs, John Jørgensen, Michael Kaiser, James Kellogg, Steven Kenyon, Richard Koenecke, Robert Kozon, Beverly LaMarr, Mike Lambertson, Anne Larson, Steven Lentine, Jesse Lewis, Michael Lilly, Kuochia Alice Liu, Andrew Malonis, Sridhar Manthripragada, Craig Markwardt, Bryan Matonak, Isaac Mcginnis, Roger Miller, Alissa Mitchell, Jason Mitchell, Jelila Mohammed, Charles Monroe, Kristina Montt de Garcia, Peter Mulé, Louis Nagao, Son Ngo, Eric Norris, Dwight Norwood, Joseph Novotka, Takashi Okajima, Lawrence Olsen, Chimaobi Onyeachu, Henry Orosco, Jacqualine Peterson, Kristina Pevear, Karen Pham, Sue Pollard, John Pope, Daniel Powers, Charles Powers, Samuel Price, Gregory Prigozhin, Julian Ramirez, Winston Reid, Ronald Remillard, Eric Rogstad, Glenn Rosecrans, John Rowe, Jennifer Sager, Claude Sanders, Bruce Savadkin, Maxine Saylor, Alexander Schaeffer, Nancy Schweiss, Sean Semper, Peter Serlemitsos, Larry Shackelford, Yang Soong, Jonathan Struebel, Michael Vezie, Joel Villasenor, Luke Winternitz, George Wofford, Michael Wright, Mike Yang, Wayne Yu
During 2014 and 2015, NASA's Neutron star Interior Composition Explorer (NICER) mission proceeded success- fully through Phase C, Design and Development. An X-ray (0.2-12 keV) astrophysics payload destined for the International Space Station, NICER is manifested for launch in early 2017 on the Commercial Resupply Services SpaceX-11 flight. Its scientific objectives are to investigate the internal structure, dynamics, and energetics of neutron stars, the densest objects in the universe. During Phase C, flight components including optics, detectors, the optical bench, pointing actuators, electronics, and others were subjected to environmental testing and integrated to form the flight payload. A custom-built facility was used to co-align and integrate the X-ray "con- centrator" optics and silicon-drift detectors. Ground calibration provided robust performance measures of the optical (at NASA's Goddard Space Flight Center) and detector (at the Massachusetts Institute of Technology) subsystems, while comprehensive functional tests prior to payload-level environmental testing met all instrument performance requirements. We describe here the implementation of NICER's major subsystems, summarize their performance and calibration, and outline the component-level testing that was successfully applied.
The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
The Soft Gamma-ray Detector (SGD) is one of science instruments onboard ASTRO-H (Hitomi) and features a wide energy band of 60{600 keV with low backgrounds. SGD is an instrument with a novel concept of "Narrow field-of-view" Compton camera where Compton kinematics is utilized to reject backgrounds which are inconsistent with the field-of-view defined by the active shield. After several years of developments, the flight hardware was fabricated and subjected to subsystem tests and satellite system tests. After a successful ASTRO-H (Hitomi) launch on February 17, 2016 and a critical phase operation of satellite and SGD in-orbit commissioning, the SGD operation was moved to the nominal observation mode on March 24, 2016. The Compton cameras and BGO-APD shields of SGD worked properly as designed. On March 25, 2016, the Crab nebula observation was performed, and, the observation data was successfully obtained.
The 6th Japanese X-ray satellite, ASTRO-H, is scheduled for launch in 2015. The hard X-ray focusing imaging system will observe astronomical objects with the sensitivity for detecting point sources with a brightness of 1/100,000 times fainter than the Crab nebula at > 10 keV. The Hard X-ray Imager (HXI) is a focal plane detector 12 m below the hard X-ray telescope (HXT) covering the energy range from 5 to 80 keV. The HXI is composed of a stacked Si/CdTe semiconductor detector module and surrounding BGO scintillators. The latter work as active shields for efficient reduction of background events caused by cosmic-ray particles, cosmic X-ray background, and in-orbit radiation activation. In this paper, we describe the detector system, and present current status of flight model development, and performance of HXI using an engineering model of HXI.
The design of the Time-Projection Chamber (TPC) Polarimeter for the Gravity and Extreme Magnetism Small Explorer (GEMS) was demonstrated to Technology Readiness Level 6 (TRL-6)3 and the flight detectors fabricated, assembled and performance tested. A single flight detector was characterized at the Brookhaven National Laboratory Synchrotron Light Source with polarized X-rays at 10 energies from 2.3–8.0 keV at five detector positions. The detector met all of the GEMS performance requirements. Lifetime measurements have shown that the existing flight design has 23 years of lifetime4, opening up the possibility of relaxing material requirements, in particular the consideration of the use of epoxy, to reduce risk elsewhere. We report on design improvements to the GEMS detector to enable a narrower transfer gap that, when operated with a lower transfer field, reduces asymmetries in the detector response. In addition, the new design reduces cost and risk by simplifying the assembly and reducing production time. Finally, we report on the performance of the narrow-gap detector in response to polarized and unpolarized X-rays.
We report a Monte-Carlo estimation of the in-orbit performance of a cosmic X-ray polarimeter designed to be installed on the focal plane of a small satellite. The simulation uses GEANT for the transport of photons and energetic particles and results from Magboltz for the transport of secondary electrons in the detector gas. We validated the simulation by comparing spectra and modulation curves with actual data taken with radioactive sources and an X-ray generator. We also estimated the in-orbit background induced by cosmic radiation in low Earth orbit.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.
We present the gain properties of the gas electron multiplier (GEM) foil in pure dimethyl ether (DME) at 190 Torr. The GEM is one of the micro pattern gas detectors and it is adopted as a key part of the X-ray polarimeter for the GEMS mission. The X-ray polarimeter is a time projection chamber operating in pure DME gas at 190 Torr. We describe experimental results of (1) the maximum gain the GEM can achieve without any discharges, (2) the linearity of the energy scale for the GEM operation, and (3) the two-dimensional gain variation of the active area. First, our experiment with 6.4 keV X-ray irradiation of the whole GEM area demonstrates that the maximum effective gain is 2 x 104 with the applied voltage of 580 V. Second, the measured energy scale is linear among three energies of 4.5, 6.4, and 8.0 keV. Third, the two-dimensional gain mapping test derives the standard deviation of the gain variability of 7% across the active area.
Polarimetry is a powerful tool for astrophysical observations that has yet to be exploited in the X-ray band. For satellite-borne and sounding rocket experiments, we have developed a photoelectric gas polarimeter to measure X-ray polarization in the 2–10 keV range utilizing a time projection chamber (TPC) and advanced micro-pattern gas electron multiplier (GEM) techniques. We carried out performance verification of a flight equivalent unit (1/4 model) which was planned to be launched on the NASA Gravity and Extreme Magnetism Small Explorer (GEMS) satellite. The test was performed at Brookhaven National Laboratory, National Synchrotron Light Source (NSLS) facility in April 2013. The polarimeter was irradiated with linearly-polarized monochromatic X-rays between 2.3 and 10.0 keV and scanned with a collimated beam at 5 different detector positions. After a systematic investigation of the detector response, a modulation factor ≥35% above 4 keV was obtained with the expected polarization angle. At energies below 4 keV where the photoelectron track becomes short, diffusion in the region between the GEM and readout strips leaves an asymmetric photoelectron image. A correction method retrieves an expected modulation angle, and the expected modulation factor, ~20% at 2.7 keV. Folding the measured values of modulation through an instrument model gives sensitivity, parameterized by minimum detectable polarization (MDP), nearly identical to that assumed at the preliminary design review (PDR).
Recent progress in wide field of view or all-sky observations such as Swift/BAT hard X-ray monitor and Fermi GeV gamma-ray observatory has opened up a new era of time-domain high energy astro-physics addressing new insight in, e.g., particle acceleration in the universe. MeV coverage with comparable sensitivity, i.e. 1 ~ 10 mCrab is missing and a new MeV all-sky observatory is needed. These new MeV mission tend to be large, power- consuming and hence expensive, and its realization is yet to come. A compact sub-MeV (0.2-2 MeV) all-sky mission is proposed as a path finder for such mission. It is based on a Si/CdTe semiconductor Compton telescope technology employed in the soft gamma-ray detector onboard ASTRO-H, to be launched in to orbit on late 2015. The mission is kept as small as 0:5 X 0:5 X 0:4 m3, 150 kg in weight and 200 W in power in place of the band coverage above a few MeV, in favor of early realization as a sub-payload to other large platforms, such as the international space station.
We performed a series of measurements using X-rays to assess the current performance of the Neutron star Interior Composition ExploreR (NICER) X-ray concentrators during the mission's concept study stage. NICER will use 56 grazing-incidence X-ray concentrators in the optical system with each module focusing the incoming photons to co-aligned silicon drift detectors with 2 mm apertures. Successful X-ray timing and navigation studies require optimal signal to noise, thus by optimizing high throughput concentrators with a large collecting area we can minimize the PSF and reduce the detector aperture size, reducing background. The performance measurements were conducted in a 600 meter X-ray beamline which collimated photons from a soft X-ray source to an X-ray CCD which was used as the detector. Several engineering test units were used to perform these studies by measuring the effective area, on and off-axis resolution, and to assess the effects of a vibration test on the module's optical performance. We have shown that the concentrators have made significant progress towards exceeding NICER's final goals.
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (60–600 keV) at a background level 10 times better than the current instruments on orbit. The SGD is complimentary to ASTRO-H’s Hard X-ray Imager covering the energy range of 5–80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes. In this paper, we will present the detailed design of the SGD and the results of the final prototype developments and evaluations. Moreover, we will also present expected performance based on the measurements with prototypes.
The Hard X-ray Imager (HXI) is one of the four detectors on board the ASTRO-H mission (6th Japanese X-ray satellite), which is scheduled to be launched in 2014. Using the hybrid structure composed of double-sided silicon strip detectors and a cadmium telluride double-sided strip detector, both with a high spatial resolution of 250 μm. Combined with the hard X-ray telescope (HXT), it consists a hard X-ray imaging spectroscopic instrument covering the energy range from 5 to 80 keV with an effective area of <300 cm2 in total at 30 keV. An energy resolution of 1–2 keV (FWHM) and lower threshold of 5 keV are both achieved with using a low noise front-end ASICs. In addition, the thick BGO active shields surrounding the main detector package is a heritage of the successful performance of the Hard X-ray Detector on board the Suzaku satellite. This feature enables the instrument to achieve an extremely good reduction of background caused by cosmic-ray particles, cosmic X-ray background, and in-orbit radiation activation. In this paper, we present the detector concept, design, latest results of the detector development, and the current status of the hardware.
The scientific objective of the X-ray Advanced Concepts Testbed (XACT) is to measure the X-ray polarization
properties of the Crab Nebula, the Crab pulsar, and the accreting binary Her X-1. Polarimetry is a powerful tool for
astrophysical investigation that has yet to be exploited in the X-ray band, where it promises unique insights into neutron
stars, black holes, and other extreme-physics environments. With powerful new enabling technologies, XACT will
demonstrate X-ray polarimetry as a practical and flight-ready astronomical technique. Additional technologies that
XACT will bring to flight readiness will also provide new X-ray optics and calibration capabilities for NASA missions
that pursue space-based X-ray spectroscopy, timing, and photometry.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy
universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV.
These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3–12 keV with
high spectral resolution of ΔE ≦ 7 eV, enabled by a micro-calorimeter array located in the focal plane of
thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5–80 keV, located in the focal plane of
multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4–12 keV,
with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera
type soft gamma-ray detector, sensitive in the 40–600 keV band. The simultaneous broad bandpass, coupled
with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
pursued.
The Hard X-ray Imager (HXI) is one of four detectors on board the ASTRO-H mission (6th Japanese X-ray
satellite), which is scheduled to be launched in 2014. Using the hybrid structure composed of double-sided silicon
strip detectors and a cadmium telluride double-sided strip detector, the instrument fully covers the energy range
of photons collected with the hard X-ray telescope up to 80 keV with a high quantum efficiency. High spatial
resolution of 250 μm and an energy resolution of 1-2 keV (FWHM) are both achieved with low noise front-end
ASICs. In addition, the thick BGO active shields surrounding the main detector package is a heritage of the
successful performance of the Hard X-ray Detector on board the Suzaku satellite. This feature enables the
instrument to achieve an extremely high background reduction caused by cosmic-ray particles, cosmic X-ray
background, and in-orbit radiation activation. In this paper, we present the detector concept, design, latest
results of the detector development, and the current status of the hardware.
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage
and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will
feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on
orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The
SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield
where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as
a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good
energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due
to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive
to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes.
The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected
launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed
description of the instrument and expected performance.
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