For the first time in the history of ground-based x-ray astronomy, the on-axis performance of the dual mirror, aspheric, aplanatic Schwarzschild-Couder optical system has been demonstrated in a 9:7-m aperture imaging atmospheric Cherenkov telescope. The novel design of the prototype Schwarzschild-Couder Telescope (pSCT) is motivated by the need of the next-generation Cherenkov Telescope Array (CTA) observatory to have the ability to perform wide (≥8°) field-of-view observations simultaneously with superior imaging of atmospheric cascades (resolution of 0:067 per pixel or better). The pSCT design, if implemented in the CTA installation, has the potential to improve significantly both the x-ray angular resolution and the off-axis sensitivity of the observatory, reaching nearly the theoretical limit of the technique and thereby making a major impact on the CTA observatory sky survey programs, follow-up observations of multi-messenger transients with poorly known initial localization, as well as on the spatially resolved spectroscopic studies of extended x-ray sources. This contribution reports on the initial alignment procedures and point-spread-function results for the challenging segmented aspheric primary and secondary mirrors of the pSCT.
The first prototype of the Schwarzschild Couder Medium Size Telescope (pSCT) proposed for the CTA observatory has been installed in 2018 at the Fred Lawrence Whipple Observatory. The pSCT camera is composed of 25 modules with 64 channels each, covering only a small portion of the full focal plane of the telescope. The Italian Institute of Nuclear Physics (INFN) has developed and characterized in collaboration with Fondazione Bruno Kessler (FBK) a new generation of Silicon Photomultipliers (SiPMs) sensitive to the Near Ultraviolet wavelengths, based on the High Density technology (NUV-HD devices). The latest generation of 6×6 mm2 SiPMs (called NUV-HD3) have been used to equip a subsection of 9 out of 25 modules of the pSCT camera. An upgrade of this camera is foreseen between 2019 and 2020 using the same sensors, aiming to equip the full focal plane with 177 modules, for a total of more than 11000 pixels. We will present a full characterization of the performance of these devices, highlighting why they are suitable for Cherenkov light detection. An overview on the overall behavior of the installed sensors will be also given, providing information on the uniformity of the sensors and of the performance of the camera.
PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~ 1.6-2.7Å. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project recently started undertaking the commissioning process of a subsystem at the Subaru Telescope side, with the integration and test processes of the other subsystems ongoing in parallel. We are aiming to start engineering night-sky operations in 2019, and observations for scientific use in 2021. This article gives an overview of the instrument, current project status and future paths forward.
The construction of a prototype Schwarzschild-Couder telescope (pSCT) started in early June 2015 at the Fred Lawrence Whipple Observatory in Southern Arizona, as a candidate medium-sized telescope for the Cherenkov Telescope Array (CTA). Compared to current Davies-Cotton telescopes, this novel instrument with an aplanatic two-mirror optical system will offer a wider field-of-view and improved angular resolution. In addition, the reduced plate scale of the camera allows the use of highly-integrated photon detectors such as silicon photo multipliers. As part of CTA, this design has the potential to greatly improve the performance of the next generation ground-based observatory for very high-energy (E>60 GeV) gamma-ray astronomy. In this contribution we present the design and performance of both optical and alignment systems of the pSCT.
The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory for very high-energy (E>100 GeV) gamma-ray astronomy. It will integrate several tens of imaging atmospheric Cherenkov telescopes (IACTs) with different apertures into a single astronomical instrument. The US part of the CTA collaboration has proposed and is developing a novel IACT design with a Schwarzschild-Couder (SC) aplanatic two-mirror optical system. In comparison with the traditional single mirror Davies-Cotton IACT the SC telescope, by design, can accommodate a wider field-of-view, with significantly improved imaging resolution. In addition, the reduced plate scale of an SC telescope makes it compatible with highly integrated cameras assembled from silicon photo multipliers. In this submission we report on the status of the development of the SC optical system, which is part of the e ort to construct a full-scale prototype telescope of this type at the Fred Lawrence Whipple Observatory in southern Arizona.
The Cherenkov Telescope Array (CTA) is the next generation very high-energy gamma-ray observatory, with at least 10
times higher sensitivity than current instruments. CTA will comprise several tens of Imaging Atmospheric Cherenkov
Telescopes (IACTs) operated in array-mode and divided into three size classes: large, medium and small telescopes. The
total reflective surface could be up to 10,000 m2 requiring unprecedented technological efforts. The properties of the
reflector directly influence the telescope performance and thus constitute a fundamental ingredient to improve and
maintain the sensitivity. The R&D status of lightweight, reliable and cost-effective mirror facets for the CTA telescope
reflectors for the different classes of telescopes is reviewed in this paper.
Laue lenses are an emerging technology allowing the concentration of soft gamma rays in the ~ 100 keV -
1.5 MeV energy range. Two lens designs based on recently measured crystals are presented in this paper. A
lens dedicated to the understanding of the progenitors and explosion physics of Type Ia supernovae through
the observation of the 847 keV line produced by the decay chain of the radionuclide 56Co. With a Compton
camera at the focus (as proposed for the DUAL mission), we find that a space-borne telescope could reach a 3-σ
sensitivity of 1.5×10-6 ph/s/cm2 for a 3% broadened line in 105 s, enabling the detection of several events per
year with enough significance to strongly constrain the models. On the other hand, a second generation prototype
is proposed. Made to realize a balloon-borne telescope focusing around the electron-positron annihilation line
(511 keV), this lens would primarily be a technological demonstrator. However with an estimated sensitivity of
5×10-6 ph/s/cm2 in 104 s observation time, this Laue lens telescope could bring new hints in the search of the
origin of the Galactic positrons. To build this prototype, a dedicated X-ray beamline has been built at the Space
Laue lenses are an emerging technology based on diffraction in crystals that allows the concentration of soft
gamma rays. This kind of optics that works in the 100 keV - 1.5 MeV band can be used to realize an highsensitivity
and high-angular resolution telescope (in a narrow field of view). This paper reviews the recent
progresses that have been done in the development of efficient crystals, in the design study and in the modelisation
of the answer of Laue lenses. Through the example of a new concept of 20 m focal length lens focusing in the 100
keV - 600 keV band, the performance of a telescope based on a Laue lens is presented. This lens, uses the most
efficient mosaic crystals in each sub-energy range in order to yield the maximum reflectivity. Imaging capabilities
are investigated and shows promising results.
In a Laue lens a large number of crystals are disposed on concentric rings such as they diffract via Braggdiffraction
the incident gamma-rays onto a common focal spot. Compact structured high-Z mosaic-crystals are
among the most efficient diffraction media for the domain of nuclear astrophysics (i.e. 300 keV ≤ E ≤ 1.5 MeV).
We have studied the potential of various high-Z crystals such as Ir, W, Au, Ag, Pt, Rh and AsGa for a Laue
lens application. The diffraction performance of gold, silver and platinum crystals have been measured during
runs at the European Synchrotron Radiation Facility and in a reactor-beamline at the Institut Laue Langevin,
Grenoble in France. Several of the tested high-Z materials show outstanding performances with reflectivities
reaching the theoretical limits for mosaic-crystals, and hence open the way towards efficient focusing optics at