Fast Timing Signals Research Articles

Correlated Energy and Time-of-Flight Measurements of Fission Fragments with Semiconductor Detectors: System Design and Performance

A system for the measurement of correlated energies and times-of-flight of fission fragments has been developed. This system, adaptable for use with other charged particles as well, includes a fast-response transformer coupling scheme in which the charge originating in a solid-state detector passes through the transformer primary to a low noise charge-sensitive amplifier; the fast timing signal is obtained from the transformer secondary. Noise thereby added to the linear energy signal is negligible. The measured time resolution of the system for particles in a narrow band of energies was ≲0.4 nsec, full-width at half-maximum. The design of the system is described, and the detailed results of performance tests, including tests with coincident 252Cf spontaneous fission fragments and energy-time correlation measurements for bromine and iodine ions (artificial fission fragments), are given.

Instrumentation at the ETH

After a brief outline of applications of scintillation counters to nuclear studies at ETH (Eidgenoessische Technische Hochschule), some topics in electronic circuit developments are selected for a more detailed discussion. 1) A linear overload-protected amplifier is described in which pulse shape parameters can be adjusted independently. 2) In the linear amplifier double rectangular pulse shaping is produced by a ferrite core delay line of novel design. Higher order phase corrections are obtained by a combination of inductive and capacitive couplings. 3) Fast timing signals are derived from slow scintillation pulses using a nonlinear amplifier circuit. Amplitude-dependent time jitter is reduced by a special design of interstage couplings. 4) Requirements to be met by pulse stretchers are listed, and a corresponding circuit diagram is presented. 5) Ultrasonic delay lines can be used for the storage of channel counts in a pulse spectrometer. A new type of magnetostrictive transducer has been developed in order to improve the reliability of such a memory. Increased signal amplitude is obtained along with a suppression of unwanted reflections. 6) Straightforward decimal coding, as used in ultrasonic storage and in electrostatic storage type pulse spectrometers, will be explained briefly. Automatic data recording from the CRT display of the ultrasonic memory spectrometer is demonstrated. The electrostatic memory spectrometer is presently operative with four decimals on each of 32 columns in the storage tube. 7) A possible way of using a pulse spectrometer for automatic computing in the analysis of complex scintillation spectra is suggested.