Prompt gamma-ray analysis (PGA) of meteorite samples, with emphasis on the determination of Si

Abstract

Neutron-induced prompt gamma-ray analysis (PGA) was applied to seven meteorite samples (Allende, Zagami, Acfer 209, ALH77005, ALH84001, EET79001 and Neagari). Samples were irradiated in both the thermal neutron and the cold neutron guided beams of JRR-3M at JAERI. Multiple samples of an Allende standard powder were analyzed for Si using two different methods: (1) the comparison method, using a Si standard, and (2) the mono-standard method, using Fe as an internal reference element. The Si concentrations determined by these two methods are in good agreement with literature values. The analytical sensitivity for Si using the cold neutron guided beam is -14.3• higher than that for the thermal neutron guided beam. Other elements determined (B, Ca, Ti and S) also showed higher sensitivities using the cold neutron beam. The other meteorites studied showed some anomalous B and S values likely due to the effects of terrestrial weathering/contamination.

An anomalous eucrite, Dhofar 007, and a possible genetic relationship with mesosiderites

“…Approximately 10 mg of the powder was used for determining REEs, whereas about 200 mg sample was used for PGE in consideration of the heterogeneity of PGE. These analytical procedures were described in Latif et al (1999), Shirai et al (2003), Shinotuska and Ebihara (1997), and for PGA, INAA, ICP-MS of REE, and ICP-MS of PGE, respectively.…”

Chemical composition of the Kobe meteorite; Neutron-induced prompt gamma ray analysis study.

“…As residual activities in irradiated samples become negligible after an appropriate cooling interval, analyzed samples can be studied using other techniques (Ebihara and Oura, 2001). When applied to meteorite samples, we reported that PGA is a very useful analytical method for the determination of Si and S in addition to other major and trace elements (Latif et al, 1999). When compared with other analytical methods for rock samples, including chondritic meteorites, such as X-ray fluorescence, electronprobe microanalysis and secondary ion mass spectrometry, PGA is unique in being both a chemically and physically non-destructive analytical method for determining the chemical composition of geochemical and cosmochemical samples.…”

Chemical characterization of the extraterrestrial material returned by future space mission: an application of nuclear activation methods

“…This is understandable in consideration of much lower neutron flux in PGA (10 7 -10 8 cm À2 s À1 ) compared with that in INAA (10 13 -10 14 cm À2 s À1 ). Nevertheless, analytical sensitivity is satisfactorily high; most major and minor elements can be determined for geological and cosmochemical samples (Latif et al, 1999).…”