4-Channel Digital Positron Lifetime Spectrometer for Studying Biological Samples
In this work a novel detector setup for PALS-studies on biomolecular materials is presented. When pursuing optimal detecting efficiency and lifetime component resolution one must make compromises when using only one detector pair. With smaller scintillation heads the resolution is higher, but the detecting efficiency decreases and vice versa. When measuring biological materials that do not withstand long measurement periods, sacrifices are made for gaining efficiency. The price of this optimization is low resolution of the lifetime components, namely separating the always present water’s lifetime component of ~1.8 ns from the actual material’s lifetime component, typically >2 ns. A solution to this problem is measuring the annihilation spectra with two individual detector pairs simultaneously. Using analog setup, it would require duplicate ADC-hardware that are both expensive and degrade by time. With a fully digital setup, the need for hardware is smaller and the precision of the setup is constant during its service life.
S. J. Wang, Z. Q. Chen, B. Wang and Y. C. Jean
P. Sane et al., "4-Channel Digital Positron Lifetime Spectrometer for Studying Biological Samples", Materials Science Forum, Vol. 607, pp. 254-256, 2009