Ultra Cold Neutrons
The "A" Correlation Experiment

Location of Research Facility:
Los Alamos National Laboratory, Los Alamos, New Mexico.

VT Research Personnel:
Dr. Bruce Vogelaar
Dr. Mark Pitt

Degrees Awarded:
Mark Makela (Ph.D. 2005)
Russell Mammei (Ph.D. 2010)

Description of Research & Links:

The well known left-handed asymmetry in the weak interaction is about the only way to let someone in a distant galaxy know what we mean by right and left. However, the energy dependence of this asymmetry is fertile ground to explore new physical phenomena, since the Standard Model makes quite firm predictions, but measurements are not quite there yet.

This experiment utilizes ultra-cold neutrons (UCN's). UCN's scatter elastically off nuclei and can thus be contained just like a ball in a box. In this experiment the box is non-magnetic so if the UCN's are put into the box polarized, they tend to stay polarized. Once in the box a UCN bounces around until it decays into a proton, neutrino, and electron; the electron is then captured by the detectors in the box and its energy and position are logged. The A-correlation is the energy dependence of asymmetry in the electron's direction relative to the neutron's polarization.

Ultra-cold neutrons source at Los Alamos confirmed as world's most intense
VT UCN Group Homepage
Los Alamos National Laboratory

Los Alamos National Lab
Los Alamos National Lab (in 1995)


beta decay
The neutron decay process.


UCNA detector
The design of the UCNA detector.

Russel Mammei

The device for applying the diamond-like coating to the neutron transfer tubes resides in the basement of Robeson Hall.


Test Chamber

Prof. Vogelaar (right) constructing the Neutron Guide Test Chamber.


The UCNA effort at Virginia Tech is, and has been, supported by the Nuclear Physics Program of the NSF, grants PHY-0099448, PHY-0401526, PHYS-0700491.

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