Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated

M-039 Geologic map of the Hungry Jack Lake quadrangle, Cook County, Minnesota

Scale 1:24,000

Platinum-group elements and chalcophile elements content in sulphide droplets from MORB glass

Most models of how PGE deposits form suggest that a sulphide liquid collects the PGE and concentrates them in a zone sufficiently rich in PGE to be exploited. If this were the case then one might expect the PGE to be present in solid solution in magmatic base metal sulphides (BMS) such as pyrrhotite (po), pentlandite (pn) and chalcopyrite (ccp). However, in most ores studied to date PGM account for a large part of the PGE budget. The origin of these PGM could be: exsolution from the BMS, crystallization from the sulphide liquid, or precipitation from a deuteric fluid. Sulphide droplets from MORB represent natural examples of rapidly quenched sulphide liquid. Thus, it is possible that exsolution did not occur and that deuteric processes were not important. Furthermore, the sulphide liquid would not have fractionated sufficiently to crystallize PGM. To test these ideas we are determining PGE and chalcophile element contents of sulphide droplets in MORB glasses

Platinum-group elements and chalcophile elements content in sulphide droplets from MORB glass

Most models of how PGE deposits form suggest that a sulphide liquid collects the PGE and concentrates them in a zone sufficiently rich in PGE to be exploited. If this were the case then one might expect the PGE to be present in solid solution in magmatic base metal sulphides (BMS) such as pyrrhotite (po), pentlandite (pn) and chalcopyrite (ccp). However, in most ores studied to date PGM account for a large part of the PGE budget. The origin of these PGM could be: exsolution from the BMS, crystallization from the sulphide liquid, or precipitation from a deuteric fluid. Sulphide droplets from MORB represent natural examples of rapidly quenched sulphide liquid. Thus, it is possible that exsolution did not occur and that deuteric processes were not important. Furthermore, the sulphide liquid would not have fractionated sufficiently to crystallize PGM. To test these ideas we are determining PGE and chalcophile element contents of sulphide droplets in MORB glasses

The zircon bearing chromitites of the phlogopite peridotite of Finero (Ivrea zone, Southern Alps): evidence and geochronology of a metasomatized mantle slab

The phlogopite peridotite unit of the Finero Complex is a restitic harzburgite that records two metasomatic events. The first event is related to the intrusion of basaltic magma, which reacted with the pyroxene of the host harzburgite to produce chromitite pods with dunite haloes. It also produced secondary clinopyroxene and amphibole in the harzburgite in Na and the light rare earth elements. The second metasomatic event is related to the later intrusion of clinopyroxenitic dykes. During this event, water-rich vapour penetrated the harzburgite along fractures and reacted with it to form phlogopite thus enriching the rock in K. Chromitites host zircons that yield an age for the first metasomatic event of 207.9 +1.7/-1.3 Ma, during which time extensional tectonics prevailed in the Southern Alps