Techniques have been developed for the synthesis of pulse shapes using fast digital schemes in place of the traditional analog methods of pulse shaping. Efficient recursive algorithms have been developed that allow real time implementation of a shaper that can produce either trapezoidal or triangular pulse shapes. Other recursive techniques are presented which allow a synthesis of finite cusp-like shapes. Preliminary experimental tests show potential advantages of using these techniques in high resolution, high count rate pulse spectroscopy .

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Recursive algorithms for real-time digital pulse shaping in pulse height measurements have been developed. The differentiated signal from the preamplifier (exponential pulse) is amplified and then digitized. Digital data are deconvolved so that the response of the high-pass network is eliminated. The deconvolved pulse is processed by a time-invariant digital filter which allows trapezoidal/ triangular or cusp-like shapes to be synthesized . A prototype of a digital trapezoidal processor was built which is capable of sampling and processing digital data in real time at clock rates up to 50 MHz.

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The gamma-ray excited, temperature dependent scintillation characteristics of CsI(Tl) are reported over the temperature range of-100 to +50°C. The modified Bollinger-Thomas and shaped square wave methods were used to measure the rise and decay times. Emission spectra were measured using a monochromator and corrected for monochromator and photocathode spectral efficiencies. The shaped square wave method was also used to determine the scintillation yield as was a current mode method. The thermoluminescence emissions of CsI(TI) were measured using the same current mode method. At room temperature, CsI(T1) was found to have two primary decay components with decay time constants of T1=679±10 ns (63.7%) and T z = 3.34±0.14 Ws (36.1%), and to have emission bands at about 400 and 560 rim. The T1 luminescent state was observed to be populated by an exponential process with a resulting rise time constant of 19 .6±1 .9 ns at room temperature. An ultra-fast decay component with a < 0.5 ns decay time was found to emit about 0.2% (about 100 photons/MeV) of the total scintillation light. Except for the ultra-fast decay time, the rise and decay time constants were observed to increase exponentially with inverse temperature. At-80°C T1 and TZ were determined to be 2.22±0.33 ws and 18.0±2.59 ws, respectively, while the 400 rim emission band was not observed below-50°C. At +50°C the decay constants were found to be 628 ns (70.5%) and 2.63 ws (29.3%) and both emission bands were present. The scintillation yield of CsI(TI) was observed to be only slightly temperature dependent between-30 and +50°C, peaking at about-30°C (about 6% above the room temperature yield) and monotonically decreasing above and below this temperature. Four different commercially available CsI(TI) crystals were used. Minimal variations in the measured scintillation characteristics were observed among these four crystals. Thermoluminescence emissions were observed to have peak yields at-90,-65,-40, +20, and possibly-55°C. The relative magnitudes and number of thermolummescence peaks were found to vary from crystal to crystal.

This article describes novel techniques to directly measure the electron mobility and mean free drift time product e e in semiconductor detectors. These methods are based on newly developed single polarity charge sensing and depth sensing techniques. Compared with conventional methods based on the Hecht relation, the new methods do not involve curve fitting, are less sensitive to the variation of pulse rise times, and allow the use of higher energy ␥ rays typical of many applications.