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 m<sup>2</sup> 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 <sup>56</sup>Co. 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<sup>-6</sup> ph/s/cm<sup>2</sup> for a 3% broadened line in 10<sup>5</sup> 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<sup>-6</sup> ph/s/cm<sup>2</sup> in 10<sup>4</sup> 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