The Palmas de Monte Alto meteorite: mineral chemistry and petrographic features

Several parameters have been used to classify iron meteorites, mainly mineralogy and chemical and structural properties. This paper presents these classificatory parameters, allowing a more detailed view to enlarge knowledge about the Palmas de Monte Alto meteorite. This siderite was found on the top of Monte Alto ridge, before 1955, being one of the six specimens that compose the Bahia State meteorite collection. It consists of a single mass of 97 kg which shows a highstage of oxidation in places where the crust has been removed. Its mineralogy includes kamacite, taenite, plessite, as well as secondary mineral phases such the Fe-Ni oxide akaganeite. There are also accessory minerals of common occurrence in Fe-Ni alloys of spatial origin like schreibersite, chromite and troilite, and a rare solid solution of Fe-Mn orthophosphates composed by the minerals heterosite-purpurite or sarcopside-graftonite as extreme members. The average width of its bands of kamacita (0.95 ± 0.15 mm) allows classifying it structurally as a medium octahedrite, with a medium and well-defined Windmasttaten pattern. Its contents of Ni (9.40 wt %) and Co (0.46 wt %) — compared to trace-elements Ga (22 ppm), Ir (0.70 ppm), As (16.00 ppm) and Au (1.70 ppm) — recommend the inclusion of this meteorite in the chemical group IIIAB.Diversos parâmetros têm sido utilizados para a classificação dos meteoritos de ferro, principalmente sua mineralogia e suas propriedades químicas e estruturais. Este artigo resgata e documenta o achado do meteorito férreo Palmas de Monte Alto, apresentando uma sequência de parâmetros classificatórios que amplia e detalha os dados disponíveis sobre o fragmento. Esse meteorito, um siderito, foi achado no topo da serra de Monte Alto antes de 1955 e hoje representa um dos seis espécimes que compõem a coleção de meteoritos do estado da Bahia. Ele é constituído de uma única massa de 97 kg com alto estágio de oxidação externa em locais em que a crosta de fusão foi removida. Sua mineralogia inclui kamacita, taenita e plessita, bem como fases minerais secundárias, tais como o óxido de Fe-Ni akaganeíta. Também estão presentes minerais acessórios de ocorrência comum em ligas metálicas de Fe-Ni de origem espacial, isto é, schreibersita, cromita e troilita, e foi identificada uma rara solução sólida de ortofosfatos de Fe-Mn composta dos minerais heterosita-purpurita ou sarcopsida-graftonita como membros extremos. A largura média de suas lamelas de kamacita (0,95 ± 0,15 mm) permite classificar estruturalmente o meteorito como um octaedrito médio, com padrão Widmanstätten médio e bem definido. Seus teores de Ni (9,40 wt%) e Co (0,46 wt%) comparados aos elementos-traço Ga (22 ppm), Ir (0,70 ppm), As (16,00 ppm) e Au (1,70 ppm) recomendam a inclusão desse meteorito no grupo químico IIIAB

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

Peer reviewe

CMS Data Processing Workflows during an Extended Cosmic Ray Run

Peer reviewe

Aligning the CMS Muon Chambers with the Muon Alignment System during an Extended Cosmic Ray Run

Peer reviewe

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]