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Introduction - Group Research Activities

Dr. Korsch's main research interests are understanding the fundamental structure of quantum-chromo dynamics and the violation of discrete symmetries in nature. One of his recent activities is related to the lifetime of the neutron. The neutron is a fundamental building block of Nature since it is responsible, together with protons, for the existence of different nuclei. A neutron, when not bound to a nucleus, lives only about 880 s. Unfortunately the lifetime of the neutron is only known to a few seconds and a reduction of this uncertainty is of crucial importance. The lifetime is an important parameter in the process of Big Bang nuclear synthesis. When protons and neutrons emerged after the Big Bang, they could form deuterons, which again could form helium-4 nuclei, and so on. This process is believed to be responsible for the creation of our visible baryonic (atomic) matter. However, since free neutrons decay, this whole production chain depends on the total number of neutrons at a certain point in pace-time. A shorter lifetime would yield a lower number of neutrons whereas a longer lifetime would increase the number of neutrons. Either direction will have an impact on the visible matter of our universe. In addition, Dr. Korsch is involved in studies of neutron spin structure at Jeferson Lab and the search for a permanent electric dipole moment of the neutron at the SNS (Oak Ridge National Laboratory). His group typically consists or up to three graduate students and several undergraduate students.

Precision Determination of the Neutron Lifetime:

The precise knowledge of the lifetime of a free neutron is important in many aspects of physics. It is a fundamental property of the neutron such as the mass or its magnetic moment. At present, the lifetime has been determined with a accuracy of about 1%. A new 1 experiment to measure this quantity with a relative precision of better than 10^3 is being conceived. In order to accomplish this goal, cold neutrons in one of the beamlines at NIST will pass through a solenoidal magnet where some of them can decay. The emerging protons will be trapped in a combination of the strong magnetic_eld (_ 3 T) and an electric _eld. From there they will be guided to a silicon based charged particle detector where they are counted. It is very important to understand proton transport and detection in great detail. Monte Carlo simulations of charged particle tracking in electric and magnetic _elds at low energies have to be performed. This will be done using Geant4 as a framework. In order to achieve the needed precision large_elds have to be stored on memory and the paths of the protons have to be integrated very accurately. This experiment is a collaborative e_ort with Hampton College, NIST, ORNL, Tulane University, University of Indiana, and University of Tennessee.

Participants:

People who will work on the DLX cluster:
_ W. Korsch (PI)
_ UK graduate student: Bryan Llgier

Computational Methods:

Describe the computational methods to be used, and note whether the methods are currently available at UK, commercially available, or in development The simulations will be performed using Geant4 which is a C++ based software package freely available from CERN. Some new classes will be developed and added by the PI. The graphics display will be based on Qt. The analysis will be performed using the ROOT package from CERN. All software used in this project is free. Since of order 10 Million protons will have to be tracked multithreading is essential. Geant4 supports multithreaded mode where the numbers of nodes can be speci_ed at run time.

Software:

List all the software's each individual project will be using.
Geant4 (CERN):
A toolkit for the simulation of the passage of particles through matter and _elds
ROOT (CERN):
Data Analysis Framework _ Qt (free version) 2
Some free GNU libraries such as gsl.

Collaborators:

For now only the PI will perform the MC simulations. It the intermediate future
(2017?) another graduate student might join this e_ort. No non-UK collaborators
are expected to run any simulations on the cluster.

Funding:

Department of Energy, O_ce of Nuclear Physics 3

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