High energy X-γ ray spectrometer on the Chandrayaan-1 mission to the Moon

The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX) for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the²³⁸U and²³²Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on the lunar surface by detection of the 46.5 keV line from radioactive²¹⁰Pb, a decay product of the gaseous²²²Rn, both of which are members of the²³⁸U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride (CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload configuration and plans for its realization     

On the exact evaluation of displacements within a semi-infinite solid due to a buried line source

Garvin’s variant of the Cagniard technique has been used to evaluate exactly the displacements at points within a homogeneous, isotropic, perfectly elastic, solid half space due to a buried explosive line source. The disturbance at any given time is confined to a region bounded by the free surface of the half space and theP wave front within it. The disturbance associated with the Rayleigh pulse affects a smaller region bounded by the free surface and the PP wave front.     

Isotopic and related studies of Antarctic ice samples

The ice samples obtained from Dakshin Gangotri, Antarctica show the presence of nuclear debris, attributed mainly to French nuclear explosions. Cosmogenic⁷Be occurs at levels of 30 dpm/L. The vertical profile ofδD in 6 m long drill core ranges between ?130 and ?180‰ compared to Standard Mean Ocean Water (SMOW). No systematic change with depth is seen. Small amounts of dust obtained by filtering melt water show presence of metallic spherules. Absence of elements characteristic of meteoritic or cometary debris suggests that most of them are of volcanic or industrial origin.     

http://www.sciencedirect.com/science/article/pii/S1674987113001084

We report here for the first time the composition and mineralogical studies on a new meteorite,which fell in Dhayala ki Chappar(24°58'N,73°48'27"E) 5 km NW of Nathdwara in south Rajasthan,India,on Dec.25 th,2012.Mineralogical and compositional studies were carried out on a representative piece of the Nathdwara meteorite sample.The mineralogical composition of the meteorite has been found to be olivine(42-45 vol.%),feldspar(10-15 vol.%),orthopyroxene(23-25 vol.%),troilite(6-8 vol.%),and titanium bearing minerals(6-8 vol.%).Our investigations show that the Nathdwara meteorite belongs to H6 group of ordinary chondrites.