Anti-CR2 monoclonal antibody, clone MU32 [FITC]

Cosmogenic nuclides are useful for reconstructing the cosmic-ray precompaction exposure history of the chondritic components in the early solar system. Here, we present He and Ne isotope data for 22 chondrules and 4 matrix samples from Miller Range (MIL) 090657, which is the third most pristine Renazzo-type (CR) carbonaceous chondrite (CR2.7). The studied samples contain variable mixtures of galactic cosmic ray (GCR)-produced cosmogenic noble gases and trapped noble gases of presolar origin. Remarkably, all chondrules and matrix samples have within analytical uncertainty almost identical nominal Ne-21 cosmic-ray exposure (CRE) ages in the range 3.45-6.20 Ma. The nominal He-3 CRE ages are mostly discordant, possibly due to partial H-3 and He-3 losses and/or an inaccurate correction for trapped He-3. The absence of precompaction exposure effects longer than a few Ma in MIL 090657 is at variance with data for other CR chondrites. We conclude that most CR chondrules experienced the same precompaction exposure history-although the nature of the precompaction exposure differs between the chondrites-in regions of the disk that were either exposed to or shielded from GCRs but in which exposure effects due to solar wind and/or solar cosmic rays (SCRs) were negligible. The new data do not support the X-wind model of Shu and coworkers.

GaSe crystals doped with chromium selenide 0.005-0.065 wt.% (expressed for chromium) were grown by the Bridgman technique. The crystals are characterized by perfect cleavage. It was found that the chromium concentration increases along the boule (segregation coefficient >1). It was found that the introduction of chromium selenide increases the microhardness of GaSe-based crystals up to 0.122 GPa (0.065 wt.% Cr) and does not affect substantially optical properties of the crystals.