K. Wamba

Systematic study of trace radioactive impurities in candidate construction materials for EXO-200

The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.

A Linear RFQ Ion Trap for the Enriched Xenon Observatory

The design, construction, and performance of a linear radio-frequency ion trap (RFQ) intended for use in the Enriched Xenon Observatory (EXO) are described. EXO aims to detect the neutrinoless double-beta decay of {sup 136}Xe to {sup 136}Ba. To suppress possible backgrounds EXO will complement the measurement of decay energy and, to some extent, topology of candidate events in a Xe filled detector with the identification of the daughter nucleus ({sup 136}Ba). The ion trap described here is capable of accepting, cooling, and confining individual Ba ions extracted from the site of the candidate double-beta decay event. A single trapped ion can then be identified, with a large signal-to-noise ratio, via laser spectroscopy.

A Liquid Xenon Ionization Chamber in an All-fluoropolymer Vessel

A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.

Sounding rocket mission to study the solar soft x-ray and EUV emission using transition-edge sensor technology

We are developing a new sounding rocket payload, the Advanced Technology Solar Spectroscopic Imager (ATSSI), that will use an 8 X 8 array of transition edge sensors (TES) to obtain true spectroheliograms in a spectral bandpass spanning approximately 50 eV to approximately 3 keV. The TES array will be flown at the focus of a Wolter I telescope, where it will image as 3 arc-min by 3 arc-min field of view with a pixel resolution of approximately 6 arc-sec. In this way, it will obtain approximately 1000 individual spectra with an expected average energy resolution of approximately 3 eV FWHM. In addition to the TES array, the ATSSI will employ six multilayer telescopes with bandpasses centered on atomic lines at 17.1 angstrom (Fe XVII), 195.1 angstrom (Fe XII), 171.1 angstrom (Fe IX), 57.9 angstrom (Mg X), 98.3 angstrom (Ne VIII), and 150.1 angstrom (O VI). Two additional telescopes with bandpasses centered at 1550 angstrom (C IV) and 1216 angstrom (H I) will also be used. The eight narrowband telescopes will provide high spatial resolution (<EQ 1 arc- sec), full-disk solar images and will be complemented by two grating slit spectroheliographs. One grating will obtain high resolution spectroheliograms between 2750 angstrom and 2850 angstrom (for Mg II h- and k-line studies), and the other will be multilayer-based and will probe the Fe IX/X - O V/VI complex around 171 Angstrom (73 eV). With this set of instruments, we expect to explore more fully the nature of the energy flow between small-scale coronal, chromospheric and transition region structures, as well as to address the issue of what mechanisms are responsible for heating the quiescent solar atmosphere.