PHYS40422: Applied Nuclear Physics Paul Campbell Room Interaction of Radiation with Matter 2.Radiation Detection 3.Biological Effects of Radiation 4.Applications of Nuclear Techniques 5.Nuclear Fission 6.Nuclear Fusion

Applications of Nuclear Physics 1) Medical diagnosis: X-ray imaging Radioactive tracers to examine organ function and locate tumours Radioactive isotopes in pharmaceuticals to follow their action Positron emission tomography Nuclear magnetic resonance imaging 2) Therapy Electron and photon radiotherapy Therapy using protons and other heavy charged particles Local use of radioactive sources to treat tumours Heart pacemakers powered by α-particle sources 3) Industrial and other uses Sterilisation by strong sources Thickness monitoring in manufacture of thin materials Looking for leaks in underground pipes Testing welds in installed pipework 4) The use of long-lived isotopes produced by cosmic rays Dating of artefacts ( 14 C) Study of ancient groundwaters ( 36 Cl) Study of aluminium toxicity ( 26 Al)

Single beam irradiation with photons or electrons

Comparison with four beam irradiation

The benefits of fractionation of dose (several hours between dose fractions)

Effect of putting patient into an oxygen chamber no change in sensitivity increase in sensitivity

Effect of local oxygen starvation decrease in sensitivity no change

The Waikato Laboratory in New Zealand determines 14 C activity through the measurement of beta particles. Samples are converted to benzene. Residual radiocarbon activity is measured using ten Liquid Scintillation (LS) low-background spectrometers. The spectrometers have extensive shielding designed to reduce the effects of background radiation, enabling both older and smaller samples to be dated more accurately. The instrument also contains twin analysers which provide information on both sample and background spectra, necessary for quality control. A rat gnawed seed A feather Linen wrapping from a mummy

Linen cloth with image in negative Burial shroud of Christ? No apparent signs of forgery Kept in Royal Chapel in the Cathedral of St. John, Turin. Small piece sent for Carbon dating.

Nature, Vol. 337, No. 6208, pp , 16th February, 1989 Dating of the Turin Shroud A piece of the shroud was divided amongst and measured independently by laboratories in Arizona, Oxford and Zurich. The final weighted mean result was that the tested samples dated from 690 (16) BP, where “present” is conventionally defined as Note the precision of the dating. This apparent age has to be converted to calendar date by calibrating with tree ring data.

Calibration curve using dendrochronological dating which can reveal the effects of natural variations in atmospheric 14 C

Published calendar date: AD at 68% confidence level ; at 95% confidence level – double valued from calibration curve Therefore date is Note “accuracy” compared to “precision” of measurement.

This date caused quite a furore. Following chemical and other tests, it is now being suggested that a mediaeval “patch” was dated! i.e. the published date is correct, but the test sample was not from the original linen of the shroud.

The layout of an accelerator-based mass spectrometry system

t is time elapsed t 1/2 is the half-life of 40 K K f is the amount of 40 K remaining in the sample Ar f is the amount of 40 Ar found in the sample. Geological dating (example): Rock originally containing potassium but no argon (molten lava formation). Over time 40 K will decay to 40 Ar, 10.9% of the time…