Award Abstract #0079767
Acquisition of a Spectrometer and Detectors for Precision Nuclear Physics Measurements of Neutron Beta Decay

NSF Org:	PHY Division of Physics
Initial Amendment Date:	July 27, 2001
Latest Amendment Date:	July 8, 2002
Award Number:	0079767
Award Instrument:	Continuing grant
Program Manager:	Bradley D. Keister PHY Division of Physics MPS Directorate for Mathematical & Physical Sciences
Start Date:	July 1, 2001
Expires:	June 30, 2003 (Estimated)
Awarded Amount to Date:	$525000
Investigator(s):	Bradley Filippone brad@krl.caltech.edu (Principal Investigator)
Sponsor:	California Institute of Technology 1200 E California Blvd PASADENA, CA 91125 626/395-6219
NSF Program(s):	NUCLEAR PRECISION MEASUREMENTS
Field Application(s):
Program Reference Code(s):	OTHR, 0000
Program Element Code(s):	1234

ABSTRACT

A superconducting solenoidal spectrometer and state-of-the-art detectors

for low energy electrons will be used for a series of high precision

measurements of neutron beta-decay using, for the first time,

Ultra-Cold Neutrons (UCN). In particular the angular correlation (A)

between the neutron spin direction and the electron momentum will be

measured with a statistical precision of < 0.2% and substantially

smaller systematic errors. This represents nearly a factor of five

improvement over the present best measurements in an experiment with

significantly different and considerably smaller systematic uncertainties.

High-precision measurements of the A-correlation in neutron beta-decay

can be combined with measurements of the neutron and muon lifetimes to

extract the u-quark/d-quark weak mixing also known as V_ud -

a key component of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Improved

measurements of V_ud can provide access to physics beyond the

Standard Model by testing the unitarity of this matrix.

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