کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1823889 | 1526454 | 2012 | 5 صفحه PDF | دانلود رایگان |
In terms of energy resolution, temporal response to burst events, and thermal stability, lanthanum bromide doped with Ce is a much better choice than the traditional NaI(Tl) scintillator for hard X-ray astronomy. We present the test results of a phoswich detector with a diameter of 101.6 mm consisting of 6 mm thick LaBr3:Ce and 40 mm thick NaI(Tl), which is the largest one of this type reported so far. The measured energy resolution is 10.6% at 60 keV, varying inversely proportional to the square root of the energy, and the energy nonlinearity is found to be less than 1%, as good as those of smaller phoswiches. The coupled scintillators and phototube also show excellent uniformity across the detecting surface, with a deviation of 0.7% on the pulse amplitude produced by 60 keV gamma-rays. Thanks to the large ratio of light decay times of NaI(Tl) and LaBr3:Ce, 250 ns versus 16 ns, pulse shape discrimination is much easier for this combination than for NaI(Tl)/CsI(Na). As the light decay time of LaBr3:Ce is about 15 times faster than that of NaI(Tl), this phoswich is more suitable for detection of bright, transient sources such as gamma-ray bursts and soft gamma-ray repeaters. The internal activity of lanthanum produces a count rate of about 6 counts s−1 at 37.5 keV in the detector. This peak could be used for in-flight spectral calibration and gain correction.
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 671, 11 April 2012, Pages 24–28