Details of Grant 

EPSRC Reference:	EP/G068690/1
Title:	A new method for studying laser and electron interactions for a wide range of atomic targets - collision studies in an optical enhancement cavity
Principal Investigator:	Murray, Professor AJ
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Physics and Astronomy
Organisation:	University of Manchester, The
Scheme:	Standard Research
Starts:	21 September 2009	Ends:	20 March 2013	Value (£):	544,481
EPSRC Research Topic Classifications:	Light-Matter Interactions Scattering & Spectroscopy
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:
Panel History:	Panel Date Panel Name Outcome 29 Apr 2009 Physics Prioritisation Panel Meeting Announced
Summary on Grant Application Form
One of the most fundamental processes to be understood in physics is how atoms are excited by collision with different particles such as electrons. This process occurs in many areas from the production of lighting, the development of lasers, ionospheric and atmospheric processes of importance to climate change, lightning discharges, astrophysical processes as in stars and planets, the spectroscopy of atoms and molecules and in all industries using electricity. It is essential to understand these processes at a fundamental level so new technologies can be developed, and so we can apply our knowledge to further understanding of climate change and the structure of the universe.The most detailed information on these processes is obtained by experimentally determining the 'shape' of an excited atom following inelastic scattering of an electron. We can do this by studying the light emitted from the atom as it relaxes back to the ground state. The result of these studies as a function of the electron scattering angle are then compared to predictions from sophisticated quantum theories. A new technique recently developed in Manchester allows us to measure the shape of the atom over ALL scattering angles - a task that has been impossible previously. These experiments use a specially designed magnetic field to steer electrons to and from the interaction region so all angles can be accessed. A laser beam prepares the atoms in an excited state prior to the collision, and so the electrons scatter with more energy than they had prior to the collision (super-elastic scattering). We then detect these higher energy electrons as a function of properties of the laser beam. The experiments therefore effectively reverse time - instead of starting with an electron and then looking for a photon from the excited atom, we start with a laser photon and then look for the emerging electron! By doing this, the experiments produce data thousands of times faster than using standard techniques (since the laser beam is always sent in the same direction). By adopting these methods, we can very precisely determine the shape of the atom for comparison to theory (now being developed in the USA and Australia).The apparatus in Manchester is now the most sophisticated super-elastic scattering spectrometer in the world, and has produced data never seen before. We wish to significantly extend these studies here, by incorporating an optical technique which allows us to excite many more targets than is currently possible (up to 25 new targets will be accessible compared to those which can be excited at present). To facilitate this, we will place high reflectivity mirrors around the interaction region to act as a 'storage' of light inside the spectrometer. This 'optical cavity' allows the laser power between the mirrors to be increased by up to 50 times compared to that directly from the laser. We will use this new technique to prepare atoms using UV laser radiation for the first time. Super-elastically scattered electrons will then be detected from the excited atoms, which will include zinc, silver and gold targets. These are of interest for new lighting technologies (which are currently considering using zinc as a replacement for the environmentally toxic mercury in fluorescent and UV lights), and for comparison to new quantum theories being developed to describe these complex atoms.As part of this programme we will also develop a new type of external doubling cavity that can excite two laser frequencies simultaneously from the one laser beam. This is necessary for excitation of atoms with hyperfine structure (including gold and silver), where the nuclear spin splits the energy level of the ground state. The new type of doubling cavity we will develop here will have application in a wide range of different areas of laser and atomic physics, as will the development and implementation of the optical cavity enhancement inside the spectrometer.
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Organisation Website:	http://www.man.ac.uk