B.A. Logan

A polarimeter constructed with two Si(Li) detectors

Abstract A polarimeter has been constructed using two Si(Li) detectors. The polarization sensitivity is an order of magnitude higher than that of a single Si(Li) detector of approximately the same physical dimensions. The detection efficiency of the polarimeter is much less than that of a single detector but the large increase in the polarization sensitivity is sufficient to allow the polarimeter to be superior to the single detector polarimeter.

A figure of merit for gamma-ray polarimeters

Abstract A figure of merit for gamma-ray polarimeters is proposed. Various polarimeters are analysed on the basis of the proposed figure of merit.

DETECTION OF THE PLANE OF POLARIZATION OF LINEARLY POLARIZED PHOTONS WITH A RECTANGULAR GEOMETRY Si(Li) DETECTOR.

Abstract The polarization sensitivities of some rectangular geometry lithium drifted silicon detectors have been calculated assuming 100 keV and 300 keV linearly polarized photons. The calculations show that silicon detectors are suitable for determining the plane of polarization of low energy photons. The relative merits of several commercially available detectors are discussed.

The polarisation sensitivity of a rectangular lithium drifted silicon detector

Abstract The polarisation sensitivity of a rectangular silicon detector has been investigated with linearly polarized 121 keV photons. It is shown that the detector can determine the polarisation plane of low energy polarised photons.

Improved quality of some sources of linearly polarized photons

Abstract The qualities of the reactions 24 Mg(p, p′γ) 24 Mg and 56 Fe (p, p′γ) 56 Fe, when used as sources of linearly polarized photons, have been investigated. The advantage of protons of energies higher than those commonly used is pointed out.

A polarimeter based on the photoelectric effect

Abstract A polarimeter based on the photoelectric effect has been constructed. The polarisation sensitivity results from the photoelectrons ejected from the K-shell by linearly polarised photons being emitted predominantly in the polarisation plane of the photons. A polarised photon beam obtained by the Compton scattering of a 60 Co beam was used to investigate the polarisation sensitivity and the sensitivity was found to be high. The polarimeter is capable of good energy resolution and, although the detection efficiency is low, the high polarisation sensitivity may allow a relatively low statistical accuracy to be tolerated.

A Compton spectrometer constructed with Si(Li) and Ge(Li) detectors

Abstract A Compton spectrometer has been constructed with Si(Li) and Ge(Li) detectors. The spectrometer is capable of giving a strong suppression of Compton events from high energy gamma-rays and allows weak, lower energy gamma-rays to give clear peaks in complex spectra.

A technique for investigating continuous photon distributions

Abstract A technique which is suitable for investigating photons with a continuous energy distribution is described. The experimental arrangement involves a Compton spectrometer with the two detectors of the spectrometer operated in a two dimensional pulse height analysis system. The technique is applicable to photon energy regions above 50 keV.

The optimisation of possible tests of the validity of time-reversal

Abstract Measurements of the angular correlation of cascade gamma rays from the decay of an oriented nuclear state can be used to test the validity of time-reversal invariance. Reactions induced by polarized proton beams can be used to orient suitable nuclear levels. The characteristics of some possible reactions are discussed and the relative merits of several suitable cascades are analyzed.

A source of circularly polarised photons

Abstract The inelastic scattering of a low energy polarised proton is suggested as a source of circularly polarised photons.