PH4105 Physics Laboratory 2

Further information on which modules are specific to your programme.

Module description

The aims of the module are (i) to familiarise students with a wide variety of experimental techniques and equipment, and (ii) to instil an appreciation of the significance of experiments and their results. The module consists of sub-modules on topics such as low temperature measurement techniques, solid state physics, optics, x-ray crystallography, and biophotonics.

Additional information from school

Overview

This experimental laboratory-based module builds on the Physics Laboratory 1 module, although it may also be taken as a stand-alone module where there is a programme requirement. This module is also made up of a set of sub-modules, each one lasting for four timetabled lab sessions with students undertaking five sub-modules in the course of the semester. Sub-modules presently on offer include Optics and Spectroscopy, Semiconductor Bandgap or Phase Transitions in Nickel Powders, X-ray Crystallography, Low Temperature Measurement Techniques and Biophotonics. These may change, for example as new experiments are introduced. Descriptions of the present sub-modules are given below. The class is divided into groups, usually of eight persons, which then circulate around the sub-modules sequentially. The structure of the sub-modules differs from one to another. In some, students work on the same set of experiments, at times in pairs. In others, there are a number of experiments based on a common theme; following an introductory overview, students work singly or in pairs on specific experiments. Other sub-modules aim at building basic skills such as in computer-based data handling and cryogenic handling. All the experiments are up-to-date and relevant to the training of a practising physicist, with a number of the experiments closely related to those found in contemporary research laboratories. The variety of approaches offered ensures that you will find this laboratory both enjoyable and stimulating. In addition to the experimental work, we also ask that you prepare one journal style paper on one of the sub-modules.  As practising physicists, in both academia and also often in industry, the dissemination of your research outcomes through journals is an important part of your work; this task builds experience in such style of writing.

Aims & Objectives

To give you practical experience of some pervasive experimental techniques relevant to a practising physicist, e.g. computer-based data handling, optical spectroscopy, x-ray crystallography, cryogenic techniques. To introduce you to important contemporary developments in experimental physics, e.g. low temperature material physics, lasers, Fourier transform spectroscopy, holography, optical tweezing. To strengthen your understanding of important physical concepts, e.g. phase transitions, semiconductor physics, superconductivity, scattering. To develop sound practice in a number of important generic skills such as planning of experiments, risk assessment, record keeping, data handling and evaluation, error analysis, drawing evidence-based conclusions, identifying future work. To enhance manual and mental dexterity at performing experiments. To develop transferable skills with regard to the presentation of research outcomes through both written work and oral presentations. To gain experience of carrying out experimental work while working alone, in partnership, and in small groups.

Learning Outcomes

You will have acquired: familiarity with a range of important and pervasive experimental techniques, practical experience of contemporary experimental equipment, including some used in present-day research laboratories, a fuller understanding of a range of important physical concepts through exploring them in experimental situations, key generic skills required by an experimentalist in the physical sciences, encompassing documentation, assessment, deduction, and presentation, ability to work both on your own and collaboratively.

Synopsis

Phase Transitions in Nickel Powders (PT): The experiment is to investigate the dynamics and cooperative effects of a fine ferromagnetic powder when agitated by electric and/or magnetic fields. A team of four will be expected to divide up the tasks needed to understand the electrostatic and magnetic forces involved in moving the grains; investigate the appropriateness of the design of the cell containing the powder and the coils for producing the magnetic field and of interfacing a video camera and instrumentation using LabView. The cooperative effects between the grains depend on the level of excitation in a way that loosely corresponds to phase transitions as a function of temperature. Success would be a 'phase diagram' for the system.

Optics and Spectroscopy (O&S) : This aims to give practical experience of important techniques in modern optics, particularly in spectroscopy. The first two afternoons are spent on work in pairs and small groups involving spectroscopy with prisms, gratings, Fabry-Perot interferometers, and a Fourier transform spectrometer. One experiment measures the splitting of spectral lines in neon in a magnetic field (the Zemmen Effect). A tunable coherent optical source is demonstrated. The final two afternoons are spent on an experiment of the student's choice in the area of optics and spectroscopy. These final two afternoons aim to develop experimental planning and design skills as well as the investigation techniques and exploring of science that are practised in the first three afternoons.

Semiconductors/SQUIDS (SC):

Germanium doped with gold is an extrinsic semiconductor.  By varying the temperature of the sample from 90 K to 360 K and by simultaneously monitoring its effect on the conductivity, three regions of the thermal excitation of carriers to the conduction and valence bands can be identified – the extrinsic, exhaustion and intrinsic ranges.  From the temperature variation in conductivity, the acceptor ionization energy and the main Germanium band gap will be determined.  You will also investigate the importance of four terminal measurements for metal semi-conductor junctions.

Outcomes of the experiment will

• reinforce ideas about band structures, band gaps and doping in crystalline solids,
• provide experience in the use of cryogenic fluids,
• test experimental capability on dynamic thermal experiments.

Superconducting Quantum Interference Devices- SQUIDS. This experiment serves as an introduction to superconductors and in particular to high temperature SQUIDS. These allow us to measure very small levels of magnetic flux and a variety of related quantities such as voltage. The actual measurements are very simple, but the background theory and understanding are not!

X-Ray Crystallography (X): X-Ray crystallography is among the most important methods to identify the atomic lattice structure of synthesized crystalline materials and is commonly employed in everyday research in our university. Thanks to a recent major investment in this Junior Honours experiment, you now have the chance to work with the most modern, computer controlled x-ray diffractometer available for undergraduate teaching.

On the first day of the experiment you will concentrate on becoming familiar with the experimental apparatus and the fundamental techniques in x-ray crystallography such as Laue and Debye-Scherrer diffraction as well as how to analyse the data that you obtain. However, the main focus will be the second part of the lab, which is much closer to real life research. The task here is to use the methods you have learned to analyse an unknown substance and determine its lattice structure as well as inter atomic spacings. Overall this laboratory aims at creating the opportunity for you to experience part of the everyday detective work one is confronted with in condensed matter physics research.

Low Temperature Measurement: Small cryostats with base temperatures of either 77K (using liquid nitrogen) or ~4K using liquid helium will be used for basic training in making measurements at low temperatures.  This will include handling cryogens and using temperature controllers.  Electrical resistance or magnetic susceptibility vs temperature will be used to probe the physics of materials at these very low temperatures.  This sub-module will also develop reporting skills in the preparation of a short technical report for assessment, rather than lab notebook submission.

Biophotonics: Biophotonics involves the research, development and application of existing and new optical techniques in the study of biological molecules, i.e. cells and tissues. The application of biophotonics is now widespread and where related to human biology the terms biomedical- and medical photonics have come to be used synonymously. In this biomedical field the application of biophotonic techniques may be exploited for such diverse purposes as the investigation of cell function at the most fundamental levels of cell biology, in medical diagnosis and monitoring of