Initial performance of the EXITE2 imaging phoswich detector/telescope for hard X-ray astronomy

Development of an xspec-based spectral analysis system for the coded-aperture hard X-ray balloon payload EXITE2

“…A detailed discussion of the PSD efficiencies and the actual sensitivity versus energy are given in a separate paper [13]. (We note that a previously-published calculation of the EXITE2 effective area [7] used overly-optimistic values of the imaging factors and did not include the effects of PSD rejection efficiency.) Figure 3 provides a vivid illustration of the difficulties inherent in performing sensitive imaging observations in the hard X-ray band.…”

“…(Another imaging phoswich balloon payload is the GRIP-2 telescope built by Caltech [5].) The EXITE2 payload has been described in detail previously [6][7][8][9]. Briefly, the main detector is a 36 cm × 36 cm × 1 cm NaI(Tl) crystal surrounded on five sides by 2 cm of CsI(Na).…”

Observations of Cygnus X‐1 with the EXITE2 Hard X‐Ray Balloon Payload

“…In recent years, we have designed and developed a hard X-ray imaging coded aperture telescope with the secondgeneration Energetic X-ray Imaging Telescope Experiment (EXITE2, Lum et al 1994;Manandhar 1995;Chou et al 1998;Bloser et al 2002;Chou 2001). The telescope detects and images cosmic X-ray sources in the hard X-ray band from a high-altitude balloon.…”

Simulations and measurements of the background encountered by a high-altitude balloon-borne experiment for hard X-ray astronomy

“…Full details of the original EXITE2 detector configuration, as used to obtain the flight background data discussed here ( §5), are given in [2], and only a brief summary is mentioned here. The detector itself is located between the collimator and the photomultiplier tube -4 -(PMT) array and consists of a 36 cm × 36 cm × 1 cm thick NaI(Tl) crystal surrounded on five sides by 2 cm of CsI(Na), with a 0.25 mm thick aluminum entrance window and a 1.905 cm thick glass exit window.…”

“…Because detection sensitivities are strongly dependent on this background, it must be carefully considered in the design of these instruments and interpretation of data. As part of the process of optimizing the design of the second Energetic X-ray Imaging Telescope Experiment (EXITE2) [1,2], we developed a MonteCarlo simulation code which calculates the expected in-flight background. The program propagates incident photons through the payload, determines the spectral and spatial distributions of photons which enter the detector, incorporates the detector response, and produces the energy spectrum of detected photon-induced background events.…”