The pNab experiment and the quest for ever better neutron beam polarization

Conference · Sun Jun 22 04:00:00 EDT 2025 · Proceedings of Science

DOI:https://doi.org/10.22323/1.472.0066· OSTI ID:2909372

Baessler, Stefan; Alarcon, Ricardo; Barrón Palos, Libertad; Broussard, Leah J.; Choi, Jin H.; Chupp, Tim; Crawford, Chris B.; Dodson, George; FOMIN, Nadia; Fry, Jason; Gonzalez, Frank; Hamblen, Josh; Hayen, Leendert; Jezghani, Aaron; Makela, Mark; Mammei, Russ; Mendelsohn, August; Mueller, Paul E.; Penttila, Seppo; Pioquinto, Jason A. ; Plaster, Brad; Pocanic, Dinko; Saunders, Andy; Schreyer, Wolfgang; Young, Albert R.

The Nab and pNAB collaborations are conducting a program of studies of free neutron beta decay, with the primary goal of testing the unitarity of the Cabbibo-Kobayashi-Maskawa matrix that describes quark mixing due to the weak interaction. For this purpose, a large, novel electromagnetic spectrometer, the Nab spectrometer, has been designed, built, and placed in use to determine the correlation coefficients in unpolarized neutron beta decay: "a", the neutrino-electron correlation coefficient; and "b", the Fierz term. The subject of this paper is pNAB, the second phase of the program, that will deploy the same spectrometer with a polarized neutron beam to determine "A", the beta asymmetry; and "B", the neutrino asymmetry coefficients. A focus of this paper will be on the strategies to provide a high and precisely known neutron beam polarization.

• Research Organization: Arizona State University, Tempe, AZ (United States)
• Sponsoring Organization: USDOE
• Contributing Organization: The pNAB Collaboration
• DOE Contract Number: SC0019309; AC05-00OR22725
• OSTI ID: 2909372
• Resource Type: Conference paper
• Conference Information: Journal Name: Proceedings of Science
• Country of Publication: United States
• Language: English