Precise Half-Life Measurement of the β-Decays of ^34Cl and ^34Ar
Abstract
As part of our program to test CKM unitarity via superallowed β decay, we have measured the half-lives of ^34Cl and ^34Ar, the former with higher precision and the latter with a different technique than in previous measurements. The K500 cyclotron and MARS recoil spectrometer were used to produce pure secondary beams of ^34Cl and ^34Ar. Each beam was degraded and implanted in the 76-μ m-thick aluminized Mylar tape of a fast tape-transport system. After a short time, the beam was turned off and the collected activity moved in 180 ms to the center of a 4π gas proportional counter placed in a low background region, where the β signals were multi-scaled. The collect/detect times were 3 s/35 s and 0.7 s/12 s for ^34Cl and ^34Ar respectively, and the cycles were repeated continuously. A total of 24 million ^34Cl decays and 140 million parent-daughter-combined decays of ^34Cl and ^34Ar were recorded with various settings of the discriminator threshold, detector bias and dominant dead time. No indication of systematic bias was observed. Moreover, as argon is a noble gas, we tested, with 1.77-s ^35Ar, that the implanted argon nuclei do not distort the half-life by diffusing out of the tape within the detect time. Our preliminary results for the half-lives of ^34Cl and ^34Ar are 1527.1(5) ms and 847.0(37) ms, respectively.
- Publication:
-
APS April Meeting Abstracts
- Pub Date:
- April 2003
- Bibcode:
- 2003APS..APR.B8002I