3D position sensing on UltraPeRL CdZnTe detectors
Experimental results of depth and lateral position sensing on UltraPeRL pixellated CdZnTe detectors using signal ratios are presented. Each detector employs one CdZnTe crystal of 20 mm times 20 mm times 5 mm with 8 times 8 pixel electrodes fabricated on the anode surface. The anode pixel pitch is 2.4 mm. The signal ratios are calculated using the signals induced on the collecting pixel and the eight neighboring pixels. The signal on each collecting pixel is then corrected for depth of interaction using the signal ratios. We obtained 7.6%, 4.2% and 2.5% FWHM energy resolution at 122 keV, 356 keV and 662 keV, respectively.
CZT imaging detectors for ProtoEXIST
We describe the detector development for a balloon-borne wide-field hard X-ray (20-600 keV) telescope, ProtoEXIST. ProtoEXIST is a pathfinder for both technology and science of the proposed implementation of the Black Hole Finder Probe, Energetic X-ray Imaging Survey telescope (EXIST). The principal technology challenge is the development of large area, close-tiled modules of imaging CZT detectors (1000 cm2 for ProtoEXIST1). We review the updates of the detector design and package concept for ProtoEXIST1 and report the current development status of the CZT detectors, using calibration results of our basic detector unit - 2 x 2 x 0.5 cm CZT crystals with 2.5 mm pixels (8 x 8 array). The current prototype (Rev1) of our detector crystal unit (DCU) shows ~4.5 keV electronics noise (FWHM), and the radiation measurements show the energy resolution (FWHM) of the units is 4.7 keV (7.9%) at 59.5 keV, 5.6 keV (4.6%) at 122 keV, and 7.6 keV (2.1%) at 356 keV. The new (Rev2) DCU with revised design is expected to improve the resolution by ~30%.
The colonial ethnological line: Timor and the racial geography of the Malay Archipelago
This article examines the connected histories of racial science and colonial geography in Island Southeast Asia. By focusing on the island of Timor, it explores colonial boundaries as modes of arranging racial classifications, and racial typologies as forms of articulating political geography. Portuguese physical anthropologist António Mendes Correia's work on the ethnology of East Timor is examined as expressive of these productive connections. Correia's classificatory work ingeniously blended political geography and racial taxonomy. Between 1916 and 1945, mainly based on data from the Portuguese enclave of Oecussi and Ambeno, he claimed a distinct Malayan racial type for the whole colony of ‘Portuguese Timor’. Over the years he developed an anthropogeographical theory that simultaneously aimed to reclassify East Timor and to revise the racial cartography of the Malay Archipelago, including Wallace's famous ethnological line.