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.
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.
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.
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.
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 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.
M. Feroci, J. W. den Herder, E. Bozzo, D. Barret, S. Brandt, M. Hernanz, M. van der Klis, M. Pohl, A. Santangelo, L. Stella, A. Watts, J. Wilms, S. Zane, 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, G. Baldazzi, S. Balman, M. Barbera, C. van Baren, S. Bhattacharyya, A. Baykal, T. Belloni, F. Bernardini, G. Bertuccio, S. Bianchi, A. Bianchini, P. Binko, P. Blay, F. Bocchino, P. Bodin, I. Bombaci, J.-M. Bonnet Bidaud, S. Boutloukos, L. Bradley, J. Braga, E. Brown, N. Bucciantini, L. Burderi, M. Burgay, M. Bursa, C. Budtz-Jørgensen, E. Cackett, F. Cadoux, P. Caïs, G. Caliandro, R. Campana, S. Campana, F. Capitanio, J. Casares, P. Casella, A. Castro-Tirado, E. Cavazzuti, P. Cerda-Duran, D. Chakrabarty, F. Château, J. Chenevez, J. Coker, R. Cole, A. Collura, R. Cornelisse, T. Courvoisier, A. Cros, A. Cumming, G. Cusumano, A. D'Ai, V. D'Elia, 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, S. Diebold, T. Di Salvo, I. Donnarumma, A. Drago, M. Durant, D. Emmanoulopoulos, M. H. Erkut, P. Esposito, Y. Evangelista, A. Fabian, M. Falanga, Y. Favre, C. Feldman, V. Ferrari, C. Ferrigno, M. Finger, G. Fraser, M. Frericks, F. Fuschino, M. Gabler, D. K. Galloway, J. L. Galvez Sanchez, E. Garcia-Berro, B. Gendre, S. Gezari, A. B. Giles, M. Gilfanov, P. Giommi, G. Giovannini, M. Giroletti, E. Gogus, A. Goldwurm, K. Goluchová, D. Götz, C. Gouiffes, M. Grassi, P. Groot, M. Gschwender, L. Gualtieri, C. Guidorzi, L. Guy, D. Haas, P. Haensel, M. Hailey, F. Hansen, D. Hartmann, C. A. Haswell, K. Hebeler, A. Heger, W. Hermsen, J. Homan, A. Hornstrup, R. Hudec, J. Huovelin, A. Ingram, J. In't Zand, G. Israel, K. Iwasawa, L. Izzo, H. Jacobs, F. Jetter, T. Johannsen, P. Jonker, J. Josè, P. Kaaret, G. Kanbach, V. Karas, D. Karelin, D. Kataria, L. Keek, T. Kennedy, D. Klochkov, W. Kluzniak, K. Kokkotas, S. Korpela, C. Kouveliotou, I. Kreykenbohm, L. Kuiper, I. Kuvvetli, C. Labanti, D. Lai, F. Lamb, P. Laubert, F. Lebrun, D. Lin, D. Linder, G. Lodato, F. Longo, N. Lund, T. J. Maccarone, D. Macera, S. Maestre, S. Mahmoodifar, D. Maier, P. Malcovati, I. Mandel, V. Mangano, A. Manousakis, M. Marisaldi, A. Markowitz, A. Martindale, G. Matt, I. McHardy, A. Melatos, M. Mendez, S. Mereghetti, M. Michalska, S. Migliari, R. Mignani, 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, A. Norton, M. Nowak, P. O'Brien, P. E. H. Olsen, M. Orienti, M. Orio, M. Orlandini, P. Orleański, J. Osborne, R. Osten, F. Ozel, L. Pacciani, M. Paolillo, A. Papitto, J. Paredes, A. Patruno, B. Paul, E. Perinati, A. Pellizzoni, A. V. Penacchioni, M. A. Perez, V. Petracek, C. Pittori, J. Pons, J. Portell, A. Possenti, J. Poutanen, M. Prakash, P. Le Provost, D. Psaltis, D. Rambaud, P. Ramon, G. Ramsay, M. Rapisarda, A. Rachevski, 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, P. Rodríguez-Gil, J. Rodriguez, R. Rohlfs, P. Romano, E. M. R. Rossi, A. Rozanska, A. Rousseau, F. Ryde, L. Sabau-Graziati, G. Sala, R. Salvaterra, A. Sanna, J. Sandberg, S. Scaringi, S. Schanne, J. Schee, C. Schmid, S. Shore, R. Schneider, A. Schwenk, A. Schwope, J.-Y. Seyler, A. Shearer, A. Smith, D. Smith, P. Smith, V. Sochora, P. Soffitta, P. Soleri, A. Spencer, B. Stappers, A. Steiner, N. Stergioulas, G. Stratta, T. Strohmayer, Z. Stuchlik, S. Suchy, V. Sulemainov, T. Takahashi, F. Tamburini, T. Tauris, C. Tenzer, L. Tolos, F. Tombesi, J. Tomsick, G. Torok, J. M. Torrejon, D. F. Torres, A. Tramacere, A. Trois, R. Turolla, S. Turriziani, P. Uter, P. Uttley, A. Vacchi, P. Varniere, S. Vaughan, S. Vercellone, V. Vrba, D. Walton, S. Watanabe, R. Wawrzaszek, N. Webb, N. Weinberg, H. Wende, P. Wheatley, R. Wijers, R. Wijnands, M. Wille, C. Wilson-Hodge, B. Winter, K. Wood, G. Zampa, N. Zampa, L. Zampieri, L. Zdunik, A. Zdziarski, B. Zhang, F. Zwart, M. Ayre, T. Boenke, C. Corral van Damme, Erik Kuulkers, D. Lumb
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° 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 status of the mission at the end of its Phase A study.
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 Soft Gamma-ray Detector (SGD) is one of observational instruments onboard the ASTRO-H, and will provide 10 times better sensitivity in 60{600 keV than the past and current observatories. The SGD utilizes similar technologies to the Hard X-ray Imager (HXI) onboard the ASTRO-H. The SGD achieves low background by constraining gamma-ray events within a narrow field-of-view by Compton kinematics, in addition to the BGO active shield. In this paper, we will present the results of various tests using engineering models and also report the flight model production and evaluations.
There is a large gap in between the Integral and Fermi spectral domains that is unobserved since the end of the CGRO mission and its Comptel experiment. There were many attempts to fill this gap but no proposal succeeded yet to convince a space agency to plan a mission. There are many reasons contributing to this situation but the most important one is that neither mirrors nor present particle tracking devices are effective at these energies. We propose here a novel design allowing particle tracking for a gamma-ray telescope in the 5–100 MeV band. The idea of this experiment is to image the ionizing tracks of charged particles using the light produced in a scintillator. The experiment operates as a pair creation telescope at high energy and as a Compton telescope with electron tracking at low energy. The telescope features a large scintillator transparent to the produced scintillation light, an ad-hoc optical system and a high resolution and highly sensitive imager. We review the requirements for each of these sub-systems and propose an experiment design taking into account the space constraints. We emphasize the numerous conceptual advantages of such a system as well as the identified difficulties.
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.
WPOL (Wide field camera with POLarimetry) is a wide field camera which aims to monitor the X-ray/low gamma-ray sources and measures their polarimetric properties. This camera will be operated in space to trigger a main instrument in case of transient events (gamma-ray bursts, black hole binaries state transition, supernovae, …) and to map the Xray/ gamma-ray polarized sources of the Galaxy, which has never been done up to now. It will be proposed, as an accompanying instrument, in the context of the next medium mission ESA call (M4). The concept of the instrument is based upon a coded mask imaging with a detector unit composed of two planes of Silicon double sided stripped detectors (DSSD), a passive collimator and a tungsten mask. Mapping is done on the first plane through mask imaging and polarization is measured by studying Compton scattering events between the two planes. The source direction in the sky being known through the mask pattern projected on the detector plane, and the scattered photon direction being measured between the two planes, only the determination of the first energy deposit is needed to compute the whole Compton scattering kinetics and in particular, to determine the source photon energy
M. Feroci, J. den Herder, E. Bozzo, D. Barret, S. Brandt, M. Hernanz, M. van der Klis, M. Pohl, A. Santangelo, L. Stella, A. Watts, J. Wilms, S. Zane, M. Ahangarianabhari, A. Alpar, D. Altamirano, L. Alvarez, L. Amati, C. Amoros, N. Andersson, A. Antonelli, A. Argan, R. Artigue, P. Azzarello, G. Baldazzi, S. Balman, M. Barbera, T. Belloni, G. Bertuccio, S. Bianchi, A. Bianchini, P. Bodin, J.-M. Bonnet Bidaud, S. Boutloukos, J. Braga, E. Brown, N. Bucciantini, L. Burderi, M. Bursa, C. Budtz-Jørgensen, E. Cackett, F. Cadoux, P. Cais, G. Caliandro, R. Campana, S. Campana, P. Casella, D. Chakrabarty, J. Chenevez, J. Coker, R. Cole, A. Collura, T. Courvoisier, A. Cros, A. Cumming, G. Cusumano, A. D'Ai, V. D'Elia, E. Del Monte, D. de Martino, A. De Rosa, S. Di Cosimo, S. Diebold, T. Di Salvo, I. Donnarumma, A. Drago, M. Durant, D. Emmanoulopoulos, Y. Evangelista, A. Fabian, M. Falanga, Y. Favre, C. Feldman, C. Ferrigno, M. Finger, G. Fraser, F. Fuschino, D. Galloway, J. Galvez Sanchez, E. Garcia-Berro, B. Gendre, S. Gezari, A. Giles, M. Gilfanov, P. Giommi, G. Giovannini, M. Giroletti, A. Goldwurm, D. Götz, C. Gouiffes, M. Grassi, P. Groot, C. Guidorzi, D. Haas, F. Hansen, D. Hartmann, C. A. Haswell, A. Heger, J. Homan, A. Hornstrup, R. Hudec, J. Huovelin, A. Ingram, J. J. In't Zand, J. Isern, G. Israel, L. Izzo, P. Jonker, P. Kaaret, V. Karas, D. Karelin, D. Kataria, L. Keek, T. Kennedy, D. Klochkov, W. Kluzniak, K. Kokkotas, S. Korpela, C. Kouveliotou, I. Kreykenbohm, L. Kuiper, I. Kuvvetli, C. Labanti, D. Lai, F. Lamb, F. Lebrun, D. Lin, D. Linder, G. Lodato, F. Longo, N. Lund, T. Maccarone, D. Macera, D. Maier, P. Malcovati, V. Mangano, A. Manousakis, M. Marisaldi, A. Markowitz, A. Martindale, G. Matt, I. McHardy, A. Melatos, M. Mendez, S. Migliari, R. Mignani, M. Miller, J. Miller, T. Mineo, G. Miniutti, S. Morsink, C. Motch, S. Motta, M. Mouchet, F. Muleri, A. Norton, M. Nowak, P. O'Brien, M. Orienti, M. Orio, M. Orlandini, P. Orleanski, J. Osborne, R. Osten, F. Ozel, L. Pacciani, A. Papitto, B. Paul, E. Perinati, V. Petracek, J. Portell, J. Poutanen, D. Psaltis, D. Rambaud, G. Ramsay, M. Rapisarda, A. Rachevski, P. Ray, N. Rea, S. Reddy, P. Reig, M. Reina Aranda, R. Remillard, C. Reynolds, P. Rodríguez-Gil, J. Rodriguez, P. Romano, E. M. Rossi, F. Ryde, L. Sabau-Graziati, G. Sala, R. Salvaterra, A. Sanna, S. Schanne, J. Schee, C. Schmid, A. Schwenk, A. Schwope, J.-Y. Seyler, A. Shearer, A. Smith, D. Smith, P. Smith, V. Sochora, P. Soffitta, P. Soleri, B. Stappers, B. Steltzer, N. Stergioulas, G. Stratta, T. Strohmayer, Z. Stuchlik, S. Suchy, V. Sulemainov, T. Takahashi, F. Tamburini, C. Tenzer, L. Tolos, G. Torok, J. Torrejon, D. Torres, A. Tramacere, A. Trois, S. Turriziani, P. Uter, P. Uttley, A. Vacchi, P. Varniere, S. Vaughan, S. Vercellone, V. Vrba, D. Walton, S. Watanabe, R. Wawrzaszek, N. Webb, N. Weinberg, H. Wende, P. Wheatley, R. Wijers, R. Wijnands, M. Wille, C. Wilson-Hodge, B. Winter, K. Wood, G. Zampa, N. Zampa, L. Zampieri, A. Zdziarski, B. Zhang
The LOFT mission concept is one of four candidates selected by ESA for the M3 launch opportunity as Medium Size missions of the Cosmic Vision programme. The launch window is currently planned for between 2022 and 2024. LOFT is designed to exploit the diagnostics of rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars, as well as the physical state of ultradense matter. These primary science goals will be addressed by a payload composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a collimated (<1 degree field of view) experiment operating in the energy range 2-50 keV, with a 10 m2 peak effective area and an energy resolution of 260 eV at 6 keV. The WFM will operate in the same energy range as the LAD, enabling simultaneous monitoring of a few-steradian wide field of view, with an angular resolution of <5 arcmin. The LAD and WFM experiments will allow us to investigate variability from submillisecond QPO’s to yearlong transient outbursts. In this paper we report the current status of the project.
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.
A. Goldwurm, P. Ferrando, D. Götz, P. Laurent, F. Lebrun, O. Limousin, S. Basa, W. Bertoli, Eric Delagnes, Y. Dolgorouky, O. Gevin, A. Gros, C. Gouiffes, F. Jeanneau, C. Lachaud, M. Llored, C. Olivetto, G. Prevot, D. Renaud, J. Rodriguez, C. Rossin, S. Schanne, S. Soldi, P. Varniere
The main objective of the Wide Field Monitor (WFM) on the LOFT mission is to provide unambiguous detection of the high-energy sources in a large field of view, in order to support science operations of the LOFT primary instrument, the LAD. The monitor will also provide by itself a large number of results on the timing and spectral behavior of hundreds of galactic compact objects, Active Galactic Nuclei and Gamma-Ray Bursts. The WFM is based on the coded aperture concept where a position sensitive detector records the shadow of a mask projected by the celestial sources. The proposed WFM detector plane, based on Double Sided micro-Strip Silicon Detectors (DSSD), will allow proper 2-dimensional recording of the projected shadows. Indeed the positioning of the photon interaction in the detector with equivalent fine resolution in both directions insures the best imaging capability compatible with the allocated budgets for this telescope on LOFT. We will describe here the overall configuration of this 2D-WFM and the design and characteristics of the DSSD detector plane including its imaging and spectral performances. We will also present a number of simulated results discussing the advantages that this configuration offers to LOFT. A DSSD-based WFM will in particular reduce significantly the source confusion experienced by the WFM in crowded regions of the sky like the Galactic Center and will in general increase the observatory science capability of the mission.
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.
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 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.
KEYWORDS: Space operations, Sensors, Mirrors, Spatial resolution, Physics, Space telescopes, Telescopes, Collimators, Particles, High energy astrophysics
Simbol-X is a hard X-ray mission, operating in the ~ 0.5-80 keV range, proposed as a collaboration between the French
and Italian space agencies with participation of German laboratories for a launch in 2013. Relying on two spacecraft in a
formation flying configuration, Simbol-X uses for the first time a 20-30 m focal length X-ray mirror to focus X-rays
with energy above 10 keV, resulting in over two orders of magnitude improvement in angular resolution and sensitivity
in the hard X-ray range with respect to non-focusing techniques. The Simbol-X revolutionary instrumental capabilities
will allow us to elucidate outstanding questions in high energy astrophysics such as those related to black-holes accretion
physics and census, and to particle acceleration mechanisms, which are the prime science objectives of the mission.
After having undergone a thorough assessment study performed by CNES in the context of a selection of a formation
flight scientific mission, Simbol-X has been selected for a phase A study to be jointly conducted by CNES and ASI. The
mission science objectives, the current status of the instrumentation and mission design are presented in this paper.
The mission concept MAX is a space borne crystal diffraction telescope, featuring a broad-band Laue lens optimized for the observation of compact sources in two wide energy bands of high astrophysical relevance. For the first time in this domain, gamma-rays will be focused from the large collecting area of a crystal diffraction lens onto a very small detector volume. As a consequence, the background noise is extremely low, making possible unprecedented sensitivities. The primary scientific objective of MAX is the study of type Ia supernovae by measuring intensities, shifts and shapes of their nuclear gamma-ray lines. When finally understood and calibrated, these profoundly radioactive events will be crucial in measuring the size, shape, and age of the Universe. Observing the radioactivities from a substantial sample of supernovae and novae will significantly improve our understanding of explosive nucleosynthesis. Moreover, the sensitive gamma-ray line spectroscopy performed with MAX is expected to clarify the nature of galactic microquasars (e+e- annihilation radiation from the jets), neutrons stars and pulsars, X-ray Binaries, AGN, solar flares and, last but not least, gamma-ray afterglow from gamma-burst counterparts.
IBIS, the INTEGRAL gamma-ray telescope designed to produce high-resolution images (12') over a wide field of view, covers the energy range 15 keV - 10 MeV. Its high sensitivity (mCrab level) and accurate timing (0.1 ms) are particularly well adapted to the study of the galactic and extragalactic accretion powered sources. Weekly scans of the galactic disc will allow for the detection of transient sources (e.g. X-ray novae) that may be considered as targets of opportunity. The spectral performance of IBIS (10% at 60 keV) will allow for the study of line emission from supernova remnants (44Ti), pulsars (cyclotron lines) and X-ray novae. The wide field of view will permit the detection of many serendipitous sources such as AGNs and gamma-ray bursts. The polarimetric capabilities of the telescope may also give new insights into the gamma-ray burst phenomenon.
The INTEGRAL soft gamma-ray imager (ISGRI) is a large and thin CdTe array. Operating at room temperature, this gamma camera covers the lower part (below 200 keV) of the energy domain (20 keV - 10 MeV) of the imager on board the INTEGRAL Satellite (IBIS). The ASIC's front-end electronics features particularly a low noise preamplifier, allowing a threshold below 20 keV and a pulse rise-time measurement which permits a charge loss correction. The charge loss correction and its performances are presented as well as the results of various studies on CdTe thermal behavior and radiation hardness. At higher energy (above 200 keV) ISGRI will operate in conjunction with PICsIT, the IBIS CsI gamma camera. A selection among the events in coincidence performed on the basis of the Compton scattering properties reduces strongly the background. This allows an improvement of the sensitivity and permits short term imaging and spectral studies (high energy pulsars) which otherwise would not have fit within the IBIS telemetry allocation.
To follow up on the remarkable discoveries of the Compton Gamma Ray Observatory and GRANAT, the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission was selected by ESA as part of the agency's 'HORIZON 2000' strategic plan. It is scheduled to begin detailed gamma ray spectral and imaging studies, of unprecedented resolution, in the year 2001. One of the two main INTEGRAL instruments is a high performance imager. It features a coded aperture mask and a novel large area multilayer detector which utilizes both cadmium telluride and cesium iodide elements to deliver the fine angular-resolution approximately 12 arcmin, wide spectral response (15 keV to 10 MeV) and high resolution spectroscopy (6% at 100 keV) required to satisfy the mission's imaging objectives.
The hard X-ray/soft gamma-ray telescope SIGMA has been successfully operating for more than two years aboard the soviet spacecraft GRANAT. This paper is intended to give a report of the most important technical as well as astrophysical inferences which have been obtained from this mission. From these, the mandatory capabilities of a future mission with their relative priorities can be drawn. The most important ones are (1) simultaneous spectral and imaging capabilities, (2) a wide field of view, and (3) a better sensitivity at 0.5 MeV. A sketch of a possible future satellite experiment fulfilling these requirements is given. It is a spectral imager in the sense that priority is given to the angular resolution in comparison with the spectral resolution. Its field of view (360 degree(s) X 10 degree(s)) enables continuous monitoring of the galactic plane emission, involving no cooling, no mechanics, and a coarse stabilization, it should be very reliable, thus allowing a long duration mission. A highly eccentric orbit of the same type as that of GRANAT would be the most efficient.
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