Precision measurement of the neutron's beta asymmetry using ultra-cold neutrons Conference Paper uri icon


  • A measurement of A, the correlation between the electron momentum and neutron (n) spin (the beta asymmetry) in n beta-decay, together with the n lifetime, provides a method for extracting fundamental parameters for the charged-current weak interaction of the nucleon. In particular when combined with decay measurements, one can extract the Vud element of the CKM matrix, a critical element in CKM unitarity tests. By using a new SD2 super-thermal source at LANSCE, large fluxes of UCN (ultra-cold neutrons) are expected for the UCNA project. These UCN will be 100% polarized using a 7 T magnetic field, and directed into the spectrometer. This approach, together with an expected large reduction in backgrounds, will result in an order of magnitude reduction in the critical systematic corrections associated with current n -asymmetry measurements. This paper will give an overview of the UCNA A measurement as well as an update on the status of the experiment. 2006 American Institute of Physics.

name of conference

  • PARTICLES AND NUCLEI: Seventeenth Internatinal Conference on Particles and Nuclei

published proceedings


author list (cited authors)

  • Makela, M., Back, H. O., Melconian, D., & Plaster, B.

citation count

  • 0

complete list of authors

  • Makela, M||Back, HO||Melconian, D||Plaster, B

publication date

  • July 2006


  • AIP  Publisher