Brian Pullan
University of Manchester
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Publication
Featured researches published by Brian Pullan.
Nuclear Instruments and Methods | 1975
Brian Pullan; João José Pedroso de Lima
Abstract This paper describes and discusses the performance of spark chambers which are designed to visualise the distribution of β-emitting radioactivity on chromatograms. The chambers comprise an assembly of individual detectors with spiral wire cathodes and concentric wire anodes. This design leads to ease of construction with good uniformity of sensitivity and stability of operation; sufficient for routine use in radiochromatography.
Nuclear Instruments and Methods | 1975
João José Pedroso de Lima; Brian Pullan
Abstract The main difficulty in using spark chambers in routine laboratory applications such as autoradiography is the appearance of spurious sparks which are not associated with the passage of ionisation radiation through the gas of the detectors. This paper describes an investigation of the production of initiatory electrons from the cathode surfaces of detectors by field emission effects. Electron emission rates from cathode surfaces have been measured as a function of applied electric field, cathode material and spark frequency. The results show that emission rates are high enough to account for a significant proportion of spurious sparks. Other effects leading to ionisation in the gas will also contribute to the spurious sparking rate. Conclusions are drawn as to suitable materials for spark counter cathodes.
Nuclear Instruments and Methods | 1971
J.J.P. de Lima; Brian Pullan
Abstract The position of a detected ionising particle in a Geiger counter is determined by measuring the arrival times of an avalanche at the two ends of the counter. The design of a Geiger counter and associated electronics is described. The system is capable of a position resolution of 0.4 cm and a stability of 1% in position measurement provided the voltage on the counter, the pressure and temperature are stabilised.
Physics in Medicine and Biology | 1972
J J P de Lima; Brian Pullan
The response of a spark chamber gamma camera to three-dimensional test objects has been simulated in a computer. The simulation was based on efficiency and point response function measurements for single parallel hole collimators using a Geiger counter as the detector. Measurements and simulations were also done using a NaI scintillation detector. A comparison of the two simulations shows that the product of activity in test objects and exposure time for the spark chamber system is of the order of 1000 times that for a NaI scintillation detector for the same visualization statistics. This results from the spark chambers low detection efficiency and a loss of contrast caused by an inability to discriminate against scattered radiation.
Continuity and Change | 1988
Brian Pullan
The Historical Journal | 1977
Brian Pullan
Journal of Early Modern History | 2000
Brian Pullan
The American Historical Review | 2011
Brian Pullan
The American Historical Review | 2009
Brian Pullan
The American Historical Review | 2007
Brian Pullan