J.M. D'Auria

The DRAGON facility for nuclear astrophysics at TRIUMF-ISAC: design, construction and operation

A facility for measuring cross-sections (resonance strengths) for reactions of astrophysical importance involving short-lived, radioactive reactants has been designed, built and installed at the new TRIUMF-ISAC Radioactive Beams Laboratory in Canada. Named DRAGON (Detector of Recoils And Gamma-rays of Nuclear reactions), it has been successfully commissioned with stable and radioactive heavy ion beams from ISAC. This report presents the main components of the facility, namely, the windowless gas target, the surrounding g detector array, the subsequent electromagnetic recoil mass separator, the focal plane detectors for recoils, the detection system for elastics, and the modular electronics and computer software used for the data acquisition. Examples of the operation of the facility for both stable beam reactions and the first radioactive beam reaction study, 21 Naðp;gÞ 22 Mg are also presented, along with future plans for the program. r 2003 Elsevier Science B.V. All rights reserved. PACS: 29.0

21Na(p,gamma)22Mg reaction and oxygen-neon novae.

The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in oxygen-neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be E(c.m.)=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.

Combined effect of body size, season, and location on trace element levels in mussels (Mytilus edulis)

Specimens ofMytilus edulis (mussels) were collected at one-month intervals over a one-year period from two locations in Burrard Inlet, British Columbia, Canada and less frequently from other locations in the S.W. region of B.C., and analyzed for concentrations of Mn, Fe, Cu, Zn, Br, Pb, and Sr using X-ray energy spectroscopy. Size and condition of the mussels were recorded at the same time. The data were analyzed using multiple linear regression with size and season as predictor variables and trace metal contents as criterion variables. The values of the regression coefficients changed according to whether or not the mussels were collected from a polluted environment in disagreement with previously published studies. Principal component analysis of the correlation matrix of the variables yielded three principal components one of which can be used to ascertain whether or not mussels were collected from either a polluted or an unpolluted environment.

Target and ion source development at the TISOL facility at TRIUMF

Abstract This paper presents recent developments on the TISOL (test on-line isotope separator) facility at TRIUMF with details on the ongoing work with the surface ion source as well as the newly developed ECR (electron cyclotron resonance) ion source. First measurements using the ECR ion source on-line with a thick-target isotope separator are presented. Release properties of several targets for isotope production have been measured and will be reported.

Statistical approach for deciding if mussels (Mytilus edulis) have been collected from a water body polluted with trace metals.

the 1-gallon CLS system was about half that of the 1-L systems. Comparing the results from the 1-gallon CLS study to the optimized 1-L CLS study, the mean recovery efficiency (percent) and RSD were 48% (28% RSD) and 80% (9% RSD), respectively. Of the 22 compounds tested with the optimized 1-L CLS system, 10 had recoveries >90% including a hexachlorobiphenyl isomer (M, 358). This report supports previous CLS applications papers (2-4) demonstrating that CLS-capillary column GC/MS is an excellent method to measure many toxic organics in drinking water and in groundwater. For quantitative results, recovery efficiencies of individual compounds must be determined in the same matrix as the sample matrix.

Copper levels in the muscle and liver tissue of farmed chinook salmon,Oncorhynchus tshawytscha

Abstract Farmed chinook salmon, Oncorhynchus tshawytscha , were collected from pens treated with the algicide “Amercoat 675” in which the active ingredient is copper oxide, and from untreated pens, over a 3 month period (May–August 1988). The dorsal muscle and the liver of the salmon were analysed for copper by atomic absorption spectroscopy (AAS) and X-ray fluorescence spectroscopy (XRF), respectively. Results showed that the copper concentration in the muscle decreased with increasing size of the fish, while the concentration in the liver increased. There were no statistical differences in the copper levels between salmon of comparable size raised in the two types (copper-treated vs. untreated) of enclosure.

Effects of season and seawater concentrations on trace metal concentrations in organs ofMytilus edulis

Concentrations of Pb, Cu, Zn, Fe, and Mn were measured in the gills and visceral mass ofMytilus edulis (mussels) and in the surrounding seawater (as dissolved ions and suspended particulate matter) over a one-year period (at monthly intervals) from two locations in British Columbia. Higher concentrations of Pb, Zn, and Cu were observed in tissues of mussels taken from the location containing higher levels in the seawater. All elemental concentrations in the mussels, except copper, could be correlated with seawater (dissolved ion) concentrations. Seasonal variations occurred in the Pb, Zn, Cu, and Fe mussel tissue concentrations but only occurred for soluble Fe and Zn in the surrounding seawater. Significant correlations were observed between Cu concentrations in both organs and Pb and Zn concentrations in seawater, suggesting an interelemental effect, facilitating copper uptake.

The decay scheme of 112Ag

Abstract The γ -radiations following the decay of 112 Ag have been studied with Ge(Li) detectors. The 112 Ag half-life has been measured as 3.16±0.02 h; twenty gamma radiations ranging in energy from 606.7 keV to 2829.6 keV have been observed. Gamma-gamma coincidence measurements have been performed with Ge(Li) and NaI(Tl) detectors. A decay scheme consistent with the present data is proposed.

A review of radioactive beam facilities in the world

Abstract Technical advances coupled with unique scientific opportunities are propelling the establishment of a new technique for nuclear science, namely the use of energetic radioactive heavy ion beams. Facilities now exist which can produce energetic radioactive beams (RB) in intensities and energies sufficient to perform nuclear reactions. Brief summaries are given of all such energetic RB facilities in the world (operating, under construction, or proposed) which produce beams using either the projectile fragmentation method (PFM) or the isotope on-line (ISOL) approach coupled to a post-accelerator with emphasis on ISOL based systems. An indication of some of the scientific opportunities is also presented along with some of the anticipated technical difficulties with the ISOL approach.

The ECR ion source at the TRIUMF isotope separator, TISOL

Abstract The installation at the isotope separator TISOL of a single staged ECR (electron cyclotron resonance) ion source has been completed. The source can now routinely deliver radioactive species extracted from the production target when bombarded by 500 MeV protons. Among the radioactive species detected so far are isotopes of He, C, N, O, Ne, Cl, Ar, Kr, and Xe including multiply charged states and with yields exceeding in some cases those of the ISOLDE facility at CERN. The effect of varying parameters on the operation of the source are discussed.