Johnie M. Sperinde

ELECTROMAGNETIC DELAY LINE READOUT FOR PROPORTIONAL WIRE CHAMBERS.

Abstract We describe the use of electromagnetic delay lines to read out the position of ionizing events in multi-wire proportional chambers. The delay line used is a ceramic core (non-magnetic) type with a delay of 80 nsec/cm. The readout accuracy achieved depends on the wire plane which is read out: for the positive plane which forms the electron avalanche, the accuracy is ±1 m (half the wire spacing). For the negative plane, which records the induced signal produced on a number of adjacent wires by the positive ions, the interpolation property of the delay line permits an accuracy of ±0.15 mm.

Evidence for a low-energy resonance in the three-neutron system

Abstract A study of the double charge-exchange reaction π − + 3 He π − π + + 3 n indicates resonant behavior in the three-neutron system within a few MeV of threshold. The three-neutron data from this experiment are in good agreement with the resonant behavior obtained in the three-proton system in another reaction.

Techniques for mapping the spatial distribution of stopping π− mesons in tissue

Abstract A number of processes leading to the emission of photons and neutrons in π − capture reactions are discussed for potential use in radiation therapy to determine the stopping π − region. It is concluded that the scheme of detecting collimated medium energy γ -rays is the most effective.

A method for mapping the spatial distribution of stopping pi-mesons in tissue.

A method is discussed for locating the stopping position of pi - mesons in tissue. The gamma -rays emitted following the capture process are collimated and converted to electrons. They are detected with a plastic scintillator and their position is determined with a magnetostrictive wire spark chamber. The sensitivity and resolution of the system are measured.

π− -helium inelastic interactions at 140 MeV

Abstract Excited and multineutron final states have been studied in the reaction π − + 4 He . An excited state of helium is detected at 32 ± 1 MeV. Upper limits on the existence of bound trineutrons and tetraneutrons are established. Large distortions from phase-space predictions are observed in the 3-n spectrum.

Lithium-Drifted Silicon Detector Used as a Pulse Dosimeter

A lithium-drifted silicon detector used as a pulse radiation dosimeter is described. It is used to measure the depth-dose distribution of pion beams in water. The fractional dose due to energy depositions above a particular energy in the detector can also be measured. Such measurements yield information on the distribution of ionization density. Preliminary results of the pion-beam dosimetry using this pulse dosimeter are given.

ANALYZING POWER AND PHASE-SHIFT ANALYSIS OF PROTON--HELIUM ELASTIC SCATTERING AT 70 AND 80 MeV.

Abstract A helium-filled streamer chamber was used to measure the analyzing power of proton-helium elastic scattering at 70 and 80 MeV incident proton energy. Phase-shift analyses of data at 63, 70, 80 and 94 MeV yielded solutions which vary smoothly with energy and are consistent with results at lower energies.

Self-Triggered Wipe Chambers for Radiation Imaging Purposes

Spark chambers with digitized readouts offer distinct advantages in spatial resolution and coverage over other gamma-ray imaging devices. While these chambers usually require external logic signals for triggering, in this paper we describe a method that provides self-triggering spark chambers. We also describe initial tests of a 45 × 45 cm spark chamber with 60Co and 198Au samples.