Progress on the Beam Energy Monitor for the SPIRAL2 Accelerator.

WEPF29, posterInternational audienceThe first part of the SPIRAL2 project entered last year in the end of the construction phase at GANIL in France. The facility will be composed by an ion source, a deuteron/proton source, a RFQ and a superconducting linear accelerator. The driver is planned to accelerate high intensities, up to 5 mA and 40 MeV for the deuteron beams. A monitoring system was built to measure the beam energy on the BTI line (Bench of Intermediate Test) at the exit of the RFQ. As part of theMEBT commissioning, the beamenergy will be measured on the BTI with an Epics monitoring application. At the exit of the LINAC, another system will have to measure and control the beam energy. The control consists in ensuring that the beam energy stays under a limit by taking account of the measurement uncertainty. The energy is measured by a method of time of flight; the signal is captured by non-intercepting capacitive pick-ups. This paper describes the BTI monitor interface and presents the system evolution following the design review

The Minimal Supersymmetric Standard Model: Group Summary Report

CONTENTS: 1. Synopsis, 2. The MSSM Spectrum, 3. The Physical Parameters, 4. Higgs Boson Production and Decays, 5. SUSY Particle Production and Decays, 6. Experimental Bounds on SUSY Particle Masses, 7. References.Comment: 121 pages, latex + epsfig, graphicx, axodraw, Report of the MSSM working group for the Workshop "GDR-Supersym\'etrie",France. Rep. PM/98-4

Seasonal sea ice variability in eastern Fram Strait over the last 2000 years

We present a high-resolution (ca. 50 years) biomarker-based reconstruction of seasonal sea ice conditions for the West Svalbard continental margin covering the last ca. 2k years. Our reconstruction is based on the distributions of sea ice algal (IP25) and phytoplankton (brassicasterol and HBI III) lipids in marine sediment core MSM5/5-712-1 retrieved in 2007. The individual and combined (PIP25) temporal profiles, together with estimates of spring sea ice concentration [SpSIC (%)] based on a recent calibration, suggest that sea ice conditions during the interval ca. 50–1700 AD may not have been as variable as described in previous reconstructions, with SpSIC generally in the range ca. 35–45 %. A slight enhancement in SpSIC (ca. 50 %) was identified at ca. 1600 AD, contemporaneous with the Little Ice Age, before declining steadily over the subsequent ca. 400 years to near-modern values (ca. 25 %). In contrast to these spring conditions, our data suggest that surface waters during summer months were ice free for the entire record. The decline in SpSIC in recent centuries is consistent with the known retreat of the winter ice margin from documentary sea ice records. This decrease in sea ice is possibly attributed to enhanced inflow of warm water delivered by the North Atlantic Current and/or increasing air temperatures, as shown in previous marine and terrestrial records. Comparison of our biomarker-based sea ice reconstruction with one obtained previously based on dinocyst distributions in a core from a similar location reveals partial agreement in the early–mid part of the records (ca. 50–1700 AD), but a notable divergence in the most recent ca. 300 years. We hypothesise that this divergence likely reflects the individual signatures of each proxy method, especially as the biomarker-based SpSIC estimates during this interval (\u3c25 %) are much lower than the threshold level (\u3e50 % sea ice cover) used for the dinocyst approach. Alternatively, divergence between outcomes may indicate seasonality shifts in sea ice conditions, such that a combined biomarker-dinocyst approach in future studies might provide further insights into this important parameter

Quantitative reconstruction of sea-surface conditions over the last ∼150 yr in the Beaufort Sea based on dinoflagellate cyst assemblages: the role of large-scale atmospheric circulation patterns

International audienceDinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct sea-surface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a dated 36 cm-long core collected from the Mackenzie Trough in the Canadian Beau-fort Sea. Dinocyst assemblages were used to quantitatively reconstruct the evolution of sea-surface conditions (temper-ature, salinity, sea ice) and freshwater palynomorphs fluxes were used as local paleo-river discharge indicators over the last ∼ 150 yr. Dinocyst assemblages are dominated by au-totrophic taxa (68 to 96 %). Cyst of Pentapharsodinium dalei is the dominant species throughout most of the core, except at the top where the assemblages are dominated by Op-erculodinium centrocarpum. Quantitative reconstructions of sea-surface parameters display a series of relatively warm, lower sea ice and saline episodes in surface waters, alternately with relatively cool and low salinity episodes. Variations of dinocyst fluxes and reconstructed sea-surface conditions may be closely linked to large scale atmospheric circulation patterns such as the Pacific Decadal Oscillation (PDO) and to a lesser degree, the Arctic Oscillation (AO). Positive phases of the PDO correspond to increases of dinocyst fluxes, warmer and saltier surface waters, which we associate with upwelling events of warm and relatively saline water from Pacific origin. Freshwater palynomorph fluxes increased in three phases from AD 1857 until reaching maximum values in AD 1991, suggesting that the Mackenzie River discharge followed the same trend when its discharge peaked between AD 1989 and AD 1992. The PDO mode seems to dominate the climatic variations at multi-annual to decadal timescales in the western Canadian Arctic and Beaufort Sea areas