Focal Plane Alignment and Detector Characterization for the Subaru Prime Focus Spectrograph

We describe the infrastructure being developed to align and characterize the detectors for the Subaru Measurement of Images and Redshifts (SuMIRe) Prime Focus Spectrograph (PFS). PFS will employ four three-channel spectrographs with an operating wavelength range of 3800 $AA$ to 12600 $AA$. Each spectrograph will be comprised of two visible channels and one near infrared (NIR) channel, where each channel will use a separate Schmidt camera to image the captured spectra onto their respective detectors. In the visible channels, Hamamatsu 2k x 4k CCDs will be mounted in pairs to create a single 4k x 4k detector, while the NIR channel will use a single Teledyne 4k x 4k H4RG HgCdTe device.

Detectors and cryostat design for the SuMIRe Prime Focus Spectrograph (PFS)

We describe the conceptual design of the camera cryostats, detectors, and detector readout electronics for the SuMIRe Prime Focus Spectrograph (PFS) being developed for the Subaru telescope. The SuMIRe PFS will consist of four identical spectrographs, each receiving 600 fibers from a 2400 fiber robotic positioner at the prime focus. Each spectrograph will have three channels covering wavelength ranges 3800 {AA} - 6700 {AA}, 6500 {AA} - 10000 {AA}, and 9700 {AA} - 13000 {AA}, with the dispersed light being imaged in each channel by a f/1.10 vacuum Schmidt camera. In the blue and red channels a pair of Hamamatsu 2K x 4K edge-buttable CCDs with 15 um pixels are used to form a 4K x 4K array. For the IR channel, the new Teledyne 4K x 4K, 15 um pixel, mercury-cadmium-telluride sensor with substrate removed for short-wavelength response and a 1.7 um cutoff will be used. Identical detector geometry and a nearly identical optical design allow for a common cryostat design with the only notable difference being the need for a cold radiation shield in the IR camera to mitigate thermal background. This paper describes the details of the cryostat design and cooling scheme, relevant thermal considerations and analysis, and discusses the detectors and detector readout electronics.

Pseudograph associahedra

Given a simple graph G, the graph associahedron KG is a simple polytope whose face poset is based on the connected subgraphs of G. This paper defines and constructs graph associahedra in a general context, for pseudographs with loops and multiple edges, which are also allowed to be disconnected. We then consider deformations of pseudograph associahedra as their underlying graphs are altered by edge contractions and edge deletions.