The large area detector of LOFT: the Large Observatory for X-ray Timing

Abstract

LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m2-class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be reproposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities

STROBE-X: a probe-class mission for x-ray spectroscopy and timing on timescales from microseconds to years

“…The concept and design of the LAD instrument is based on the same instrument proposed as part of the scientific payload of the LOFT mission concept. 57,58 The LAD's unprecedented collecting area is achieved through a modular and intrinsically highly redundant design. Each LAD Module hosts a set of 4 × 4 detectors with their front-end electronics and 4 × 4 collimators, supported by two grid-like frames.…”

STROBE-X: X-ray timing and spectroscopy on dynamical timescales from microseconds to years

“…The soft band (0.2-12 keV) is covered by the X-ray Concentrator Array (XRCA), an array of lightweight optics (3-m focal length) that concentrate incident photons onto small solid state detectors with CCD-like (85-130 eV) energy resolution, 100 ns time resolution, and low background rates. The harder band (2 to at least 30 keV) is covered by the Large Area Detector (LAD, [1]), comprising large-area silicon drift detectors (SDDs), with 200-240 eV energy resolution, collimated to a 1 • field-of-view with lead-glass micropore collimators. Each instrument would provide an order of magnitude improvement in effective area compared with its predecessor (NICER in the soft band and RXTE in the hard band).…”

The design of the wide field monitor for the LOFT mission

“…The main objectives of the LOFT mission are to study the effects of strong gravity and the properties of ultra-dense matter [13] [10]. This will be accomplished by the combined capabilities of the two instruments: the Large Area Detector (LAD) [20] and the Wide Field Monitor (WFM).…”