Precision measurements of the Co-60 beta-asymmetry parameter in search for tensor currents in weak interactions

0358087 - ÚJF 2011 RIV US eng J - Článek v odborném periodiku
Wauters, F. - Kraev, I. - Zákoucký, Dalibor - Beck, M. - Breitenfeldt, M. - De Leebeeck, V. - Golovko, V.V. - Kozlov, V. Yu. - Phalet, T. - Roccia, S. - Soti, G. - Tandecki, M. - Towner, I. S. - Traykov, E. - Van Gorp, S. - Severijns, N.
Precision measurements of the Co-60 beta-asymmetry parameter in search for tensor currents in weak interactions.
Physical Review. C. Roč. 82, č. 5 (2010), 055502/1-055502/14. ISSN 0556-2813
Grant CEP: GA MŠMT LA08015
Výzkumný záměr: CEZ:AV0Z10480505
Klíčová slova: NUCLEAR-MAGNETIC-RESONANCE * POSITRON DECAY * PARITY CONSERVATION
Kód oboru RIV: BG - Jaderná, atomová a mol. fyzika, urychlovače
Impakt faktor: 3.416, rok: 2010

The beta-asymmetry parameter (A) over tilde for the Gamow-Teller decay of Co-60 was measured by polarizing the radioactive nuclei with the brute-force low-temperature nuclear-orientation method. The Co-60 activity was cooled down to milliKelvin temperatures in a He-3-He-4 dilution refrigerator in an external 13-T magnetic field. The beta particles were observed by a 500-mu m-thick Si PIN diode operating at a temperature of about 10 K in a magnetic field of 0.6 T. Extensive GEANT4 Monte Carlo simulations were performed to gain control over the systematic effects. Our result, (A) over tilde = -1.014(12)(stat)(16)(syst), is in agreement with the standard-model value of -0.987(9), which includes recoil-order corrections that were addressed for the first time for this isotope. Further, it enables limits to be placed on possible tensor-type charged weak currents, as well as other physics beyond the standard model.
Trvalý link: http://hdl.handle.net/11104/0196213