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Simple delay lines have been developed for reading out active anode wire locations in multiwire proportional chambers. Anode wire positions are read out using commercial fast logic and time digitization apparatus with no special electronics required.

A new type of multiware proportional chamber with a helical cathode for delay line readout has been developed and studied in detail. It gives cathode delay line pulses nearly as large as the anode pulses, and hence is well-suited for minimum ionizing particles. Measurements on such a chamber yielded spatial resolution better than 0.33 mm fwhm for 90Sr β particles, a resolving time less than 30 ns, and maximum counting rate greater than 2 MHz. The most probable pulse height induced on the delay line by minimum ionizing particles in this chamber is approximately 8 mV.

A proportional chamber with a single wire helical cathode has been employed in the focal plane of a magnetic spectrograph for nuclear reaction studies. The spatial resolution attributable to the detector is less than 0.33 mm fwhm over its 25 cm length with particles incident at an angle of 37° to the plane of the detector. The resolution achieved with a collimated 55Fe X-ray source at normal incidence was 0.25 mm. Rates of 105 counts/s are possible before degradation of the peak shapes is observed. The d E d x resolution is 27% for protons, deuterons and tritons in the energy range of 10–16 MeV. The counter has been used with an on-line computer program to measure the 27Al(d,p)28Al and 59Co(t,d)60Co differential cross sections.

The stability of photomultiplier tube (PMT) gain for signal conditions of high pulsed anode currents requires a PMT base circuit capable of maintaining constant voltage to the last few dynodes for the pulse duration. For the experimental conditions at the Los Alamos Meson Physics Facility (LAMPF) with a macropulse duration of 500 μs at 120 Hz, conventional base circuits do not meet stability requirements. The new base circuit uses high voltage transistors to furnish pulse currents to the last four dynodes of the PMT from a single capacitor source which is recharged during the period between macropulses.

A technique employing integrating analog-to-digital converters to do pulse shape discrimination between neutron and gamma initiated scintillations in liquid scintillators is described. The technique involves a direct comparison of the fast and slow components of the light output from the scintillator.