Applied Nuclear Physics at the NUS Physics Department

Transcription

1 Applied Nuclear Physics at the NUS Physics Department Thomas Osipowicz, Department of Physics Faculty of Science, NUS

2 A few words on the history of Nuclear Physics Early 20 st century: Various types (,, ) of radiation are discovered, and the existence of nuclei is demonstrated by Rutherford s scattering experiments Quantum Mechanics revolutionizes atomic physics, quantitatively explains atomic spectra by quantization of the well known Coulomb force, thereby Chemistry becomes intelligible Nuclei were recognized as clusters of protons and neutrons, so there is clear evidence for a new force, much stronger than Coulomb force Therefore it was immediately clear that large energies are involved (typically a million times larger than chemical) Led to both military (fission & fusion bomb) and civil (power plant and others) developments WWII and the arms race drove massive investment in both experimental and theoretical nuclear physics

3 The empirical basis: 92 natural elements 1440 known isotopes Very large research effort led to extensive data on spins, parities, decay modes, g factors, quadrupole moments, lifetimes, T 1/2 (s) proton number neutron number

4 surface vibrations proton-neutron system nucleon, quark-structure Theory: rather sophisticated models available (large scale shell model, collective model, interacting boson approximation) that give insight to nuclear structure. Protons and neutrons have quark structure: the strong force is seen in terms of their interactions Since the 1980ties, nuclear physics funding was somewhat reduced, partly a reaction to political pressure over association with military and radiation fears, partly as physics research shifted focus. Large effort currently under construction: Facility for Antiproton and Ion Research (FAIR), international accelerator facility in Darmstadt, Germany, cost around (US$2 billion).

5 There is a wide range of important applications of nuclear physics, eg: Medical Radiography Computerized Tomography (CT) Positron emission tomography (PET) Magnetic Resonance Imaging (MRI) (was Nuclear Magnetic Resonance, NMR) Photon therapy Proton Therapy Art and Archaeology Authentication Nuclear dating Materials Analysis Activation analysis Accelerator mass spectrometry Secondary ion mass spectroscopy Proton induced x ray emission Rutherfold backscattering Energy Production Nuclear reactors Oil well logging R&D for next generation nuclear reactors Nuclear batteries Materials Testing and Modification Trace isotope analysis Ion implantation Surface modifications Flux pinning in high Tc superconductors Cold and ultra cold neutrons Environmental Applications Climate change monitoring Pollution control Groundwater monitoring Ocean current monitoring Radioactive waste burning Blue done at the Department of Physics, NUS Why? Radiation (ions, electrons, positrons, photons) can penetrate matter and deposit energy allows imaging and modification Nuclear decay constants are largely independent on pressure, temperature and chemical environment they can act as clocks for dating techniques. Large energies involved power generation

6 Psychology of nuclear issues difficult: Military connotations clearly not helpful Associated with radiation, which is invisible and considered dangerous Power reactor accidents somewhat more prevalent than expected Unfortunate consequences: A space probe (Philae) ran out of power after landing on the comet 67P/Churyumov Gerasimenko, because it ended up in the shade, so the solar panels cannot generate power. A Radioisotope Thermoelectric Generator (RTG), known as nuclear battery, would have avoided this. Q: Why hasn't Philae got a nuclear battery? A: Ah! Hahaha! Good question!!!. they usually contain Plutonium, which is a highly toxic material, which has a lot of safety, but also political implications.. In addition, the technology to use or build RTGs has not been developed in Europe, to a large extent for political reasons. Stephan Ulamec Philae Lander Manager, ESA at minute 50

7 Applied Nuclear Physics at the Physics Dept, NUS High resolution RBS facility Nuclear microscope Proton beam writer prototype Cell and tissue imaging beam line Next generation proton beam writing facility CIBA Layout

8 Ion Beam Technology at CIBA, NUS: Lithography, Microscopy and Ion Beam Analysis Frank Watt: Thomas Osipowicz: Proton microscopy in biomedicine High resolution RBS Mark Breese: Jeroen van Kan: Proton modification of silicon Proton beam writing Andrew Bettiol: Chammika Udalagama: Micro and Nano photonics Ion transport simulation Chan Taw Kuei: Medical Physics, Environmental Radioactivity We are setting up a new radiobiology beamline in CIBA in collaboration with the National Cancer Center Singapore (NCCS), to study fundamental particlecell interactions and to look at radiation effects on cancer cells (Proton Therapy).

9 Introduction of a Minor in Medical Physics Hospitals and other parts of the medical sector needs medical physicists: for example, aging society and lifestyle changes lead to projected increase in cancer prevalence by 300% (in 2030). Diagnostic and therapeutic systems are often based on radiation applications, so Medical Physics is, to a large extent, based on nuclear physics. No programmes exist in this field in Singapore as yet. Skills are required in many specific areas, e.g. Radiation Oncology, Proton Beam Therapy, Medical Imaging (MRI/CT/PET) and Medical Technology. PC3294 Radiation Laboratory The module provides hands on experience with modern detectors, electronics, data acquisition systems, radiation sources and other nuclear physics equipment that forms the basis for the applications of nuclear physics to Medical Physics, radiation protection and other fields. PC3232B Applied Nuclear Physics This module explores elements of nuclear physics and its applications for students who are not physics majors, it introduces the relevant nuclear physics for medical physics and other applications