Background Characterization for Thermal Ion Release Experiments with 224Ra

Kwong, H. ; /Stanford U., Phys. Dept. ; Rowson, P. ; /SLAC

Stanford Linear Accelerator Center

关键词: Testing Instrumentation,Other;    46 Instrumentation Related To Nuclear Science And Technology;    Barium 136;    Double Beta Decay;    Ionization;   

DOI  :  10.2172/877473
RP-ID  :  SLAC-TN-05-069
RP-ID  :  AC02-76SF00515
RP-ID  :  877473

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Enriched Xenon Observatory for neutrinoless double beta decay uses {sup 136}Ba identification as a means for verifying the decay's occurrence in {sup 136}Xe. A current challenge is the release of Ba ions from the Ba extraction probe, and one possible solution is to heat the probe to high temperatures to release the ions. The investigation of this method requires a characterization of the alpha decay background in our test apparatus, which uses a {sup 228}Th source that produces {sup 224}Ra daughters, the ionization energies of which are similar to those of Ba. For this purpose, we ran a background count with our apparatus maintained at a vacuum, and then three counts with the apparatus filled with Xe gas. We were able to match up our alpha spectrum in vacuum with the known decay scheme of {sup 228}Th, while the spectrum in xenon gas had too many unresolved ambiguities for an accurate characterization. We also found that the alpha decays occurred at a near-zero rate both in vacuum and in xenon gas, which indicates that the rate was determined by {sup 228}Th decays. With these background measurements, we can in the future make a more accurate measurement of the temperature dependency of the ratio of ions to neutral atoms released from the hot surface of the probe, which may lead to a successful method of Ba ion release.