Helical Delay Line Research Articles

Position-sensitive counter telescope for light and heavy ions

A position-sensitive counter telescope of 600 mm length has been developed for use in an Enge split-pole spectrograph. The device has an intrinsic position resolution of less than 0.25 mm for light and heavy ions at 45° incidence. Particle identification is provided by a gridded, 22 mm high and 140 mm deep ionization chamber which yields a total energy ( E) readout from the cathode plate. Also provided are ΔE signals and a veto signal from a segmented anode. The total energy resolution for 60 MeV 16O ions is 1%, the ΔE resolution 4.4%. The ionization chamber is backed by a fast scinillator which stops penetrating ions. Electrons from short sections of the ion trajectories are selected for position sensing by a drift field, which is perpendicular to the trajectory and to the cathode of the ionization chamber, and by two ⩽ 1 mm gaps in its anode. Proportional counter anode wires are mounted just below these collimation gaps, within 3 mm of the bare wires of a helical delay line. The helix transmits the fast pulses induced by the electron avalanches to conventional timing electronics. The detector derives its first position signal from the anode wire in the spectrograph focal plane and the second one from an anode about 70 mm downstream the ion trajectory. (The two related position measurements are complete in about 4 μs.) An angular resolution of 0.3° referred to the reaction angle was obtained. The detector has operated without loss in resolution at up 20 000 counts per second.

Helical focal plane detectors

A general description is given of the theory, design and construction of helical delay line proportional counters for position determination along the focal plane of magnetic spectrometers. A discussion of the numerous designs now in use at various facilities is also presented together with their advantages and disadvantages. Spatial resolutions of 0.3–0.5 mm appear typical of this type of position sensitive detector. The energy loss information in the proportional region is also used for particle identification in many applications. The use of helical delay lines in hybrid heavy ion detectors is also discussed.

Detection of induced pulses in proportional wire devices with resistive cathodes

If the cathode of a proportional wire device is made out of a suitably resistive material, it is possible to detect induced pulses using pick-up electrodes outside the device itself. Tests have been made on proportional tubes with helical delay lines, strips, or plates as pick-up electrodes. This method simplifies design and construction of pick-up electrodes, and furthermore allows unusual electrode arrangements.

Flat Helical Delay Lines for Position Readout along the Anode Wire in MWPC and Drift Chambers

Simple, flat helical delay lines were developed for avalanche position determination along each anode wire, for unambiguous readout of multiparticle events in multiwire drift or proportional chambers. Lines of various propagation delay and dimensions were tested with x-rays and s-rays in several gas mixtures. Avalanche position resolutions of 0.2 mm and 0.6 mm FWHM, respectively, were obtained with a line 30 cm long in non electron-attaching gases.

Two-dimensional readout of a multiwire proportional chamber using a helical delay line

It has been shown that, by using simple helical delay lines for the readout of the two outer planes of a multiwire proportional chamber, two-dimensional images can be obtained with X-rays. Spatial resolution along the direction of the sense wires of better than 400 μm has been achieved as well as data rates of 10 kHz. Rates as high as 100 kHz are possible.

Pulsed Beam Chopper for LAMPF

A pulsed beam chopper has been designed and tested for use on the 750 keV proton injector transport l ine of LAMPF. The deflection structure, which is 1 m long, is similar to the traveling wave beam deflector in a high speed oscilloscope. The proton beam travels between two deflection plates each consisting of the closely spaced turns of a helical delay line. A 5 ns long positive pulse on one helix with a simultaneous negative pulse on the other helix creates a transverse electric field in the beam region which travels with the beam. The longitudinal velocity of the electric field is matched to the proton beam velocity (~1 cm/ns) by the pitch of the helices. This scheme allows the 5 ns (5 cm) long of LAMPF to be chopped into or out of the linac with 1 ns transition times. This method avoids the constraints of resonant chopping systems and will permit completely arbitrary patterns of LAMPF micropulses to be selected and accelerated. One exotic application is the generation of pseudorandom pulse sequences for neutron time-of-flight measurements.

Proportional chambers with monofilar helical cathodes for high spatial resolution

Multiware proportional chambers with monofilar helical delay line cathodes have been developed. Spatial resolutions better than 0.33 mm fwhm have been achieved. Such chambers are easily constructed and read out and can be adapted to a large variety of geometries. The properties of monofilar helical delay lines are analyzed in detail.

Diffraction on helical acoustic-surface-wave delay lines and the concept of an anisotropic edge lens

It is shown experimentally that the straight edge between two intersecting planes on Bi12 GeO20 acts, in accordance with the diffraction scaling theorem, as an acoustic-surface-wave lens. A helical delay line can be treated as a repetitive stack of edge lenses. Under certain conditions, the ‘beam waveguide’ may be metastable.

Synthesis Of The Meander Micro Strip And HelicalDelay Lines

The mathematical models of the meander microstrip line and helical line as a four-layered printed board were applied to expose the connection between the electrical properties and the constructional parameters of the above mentioned lines. The algorithm and the programme in PASCAL for synthesis of the constructions of the multitapped meander microstrip and helical delay lines with preset electrical characteristics were worked out. The algorithm of the synthesis implies that the transmission band of the delay line is predicted by its phasefrequency response. The programme enabled us to analyse the properties of the microstrip meander and the helical delay lines.