High-Precision Measurement of Na-21 Beta-Branching
Abstract
Our research effort seeks to determine the Gamow-Teller transition strength of 21Na decay through a measurement of the decay's beta-branching ratio for the 351 keV excited state. Efforts will be made to improve the most recent figure of 5.0 (1.0) percent (H.S. Wilson et al, Phys. Rev. C, 22, 1696 (1980)) to roughly .5 percent accuracy, which will reduce a sizable source of systematic error in measurements of other properties of 21Na decay with the LBL 88" Cyclotron's laser ion trapping facility. The measurement is to be accomplished using a 21Na source generated from the 88"'s proton beam via the 24Mg(p,a) reaction. High-resolution spectroscopy will be performed on this source with a pair of approx. 800 cm3 HPGe detectors borrowed from the GAMMASPHERE experiment. The system's efficiency at 351 keV will be calibrated twice, first by 21F generated in the same source with an alpha beam by the 18O(a,p) reaction.High-precision calibration at 350 keV can then be accomplished by analysis of the 1440-351 keV cascade in 21F decay; a second measurement will then be made by the 356-81 keV cascade of a 133Ba sealed source. At present, source exposure is scheduled to begin no earlier than October, but this summer's preliminary studies of the physics and equipment involved in the experiment have not uncovered any insurmountable obstacles to our stated goal of .5 percent absolute accuracy.
- Publication:
-
APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- October 2002
- Bibcode:
- 2002APS..DNP5P1070C