983 research outputs found

    Proposal for the installation of three additional OTR monitors in the TT2 line

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    The location of a set of three MTV monitors equipped with OTR (Optical Transition Radiation)screens in the line TT2 is proposed, in order to measure emittance and Twiss parameters of beams ejected from the PS when they are not sent to TT10/SPS and as a complement of downstream measurements. The monitors will be installed during the 2008-2009 machine shutdown

    Investigations into the assembly behaviour of a 'rigidified': P-carboxylatocalix[4]arene

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    The p-carboxylatocalix[4]arenes have been shown to be versatile supramolecular building blocks capable of forming a range of bi-layers, capsules and nanoscale tubules in the solid state. Here we report the synthesis of a new 'rigidified' analogue, as well as investigations into its self-assembly and related coordination chemistry. These behaviours are reminiscent of other p-carboxylatocalix[4]arenes despite the presence of rigidifying groups at the lower-rim, suggesting that this building block may be further exploited in the assembly of a range of new metal-organic cages and coordination polymers

    Tracking Study of the Effect of BPM Impedances in the SPS

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    Following the observation of a Transverse Mode Coupling Instability (TMCI) in the SPS [1, 2], a systematic estimate of the impedance of the various pieces of equipment installed in the machine has started. In this report the contribution of the Beam Position Monitor trapped modes to the global transverse impedance is considered. The trapped modes have been thus calculated with MAFIA and characterized with their resonator parameters. These impedances have been subsequently fed into the MOSES and HEADTAIL codes in order to evaluate the expected TMCI threshold in the SPS and compare it with the experimental observations

    Alternative bunch filling schemes for the LHC

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    The standard batches transfered from the PS to the SPS consist of 72 bunches each (in 3.6 s PS cycle). Alternative schemes with 48 bunches per batch (in 2.4 s PS cycle) have been investigated as backup solutions or in case of problems. The implications for the performance and the injector chain have been studied and are presented. Only filling schemes for proton operation are considered. Other filling schemes such as the bunch disposition for ion operation are not changed

    Optics Measurements and Matching of TT2-TT10 Line for Injection of the LHC Beam in the SPS

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    A well matched injection in the SPS is very important for preserving the emittance of the LHC beam. The paper presents the algorithms used for the analysis and the results of the optics measurements done in the transfer line TT2-TT10 and in the SPS. The dispersion is computed by varying the beam momentum and recording the offsets at the BPMs, while the Twiss parameters and emittance measurements in TT2-TT10 are performed with beam profile monitors equipped with OTR screens. These results are completed by those obtained with a matching monitor installed in the SPS as a prototype for the LHC. This device makes use of an OTR screen and a fast acquisition system, to get the turn by turn beam profiles right at injection in the ring, from which the beam mismatch is computed and compared with the results obtained in the line. Finally, on the basis of such measurements, a betatron and dispersion matching of TT2-TT10 for injection in the SPS has been performed and successfully put in operation

    Baseline LHC machine parameters and configuration of the 2015 proton run

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    This paper shows the baseline LHC machine parameters for the 2015 start-up. Many systems have been upgraded during LS1 and in 2015 the LHC will operate at a higher energy than before and with a tighter filling scheme. Therefore, the 2015 commissioning phase risks to be less smooth than in 2012. The proposed starting configuration puts the focus on feasibility rather than peak performance and includes margins for operational uncertainties. Instead, once beam experience and a better machine knowledge has been obtained, a push in β\beta^* and performance can be envisaged. In this paper, the focus is on collimation settings and reach in β\beta^*---other parameters are covered in greater depth by other papers in these proceedings.Comment: submitted for publication in a CERN yellow report (Proceedings of the LHC Performance Workshop - Chamonix 2014

    Considerations on the Transverse Emittance of the Fixed-Target Beam in the SPS in the PS2 Era

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    The range of the acceptable transverse emittances the Fixed-Target beams delivered to the SPS in the PS2 era is determined based on acceptance and other beam dynamics considerations in the SPS

    Earth feature identification for onboard multispectral data editing: Computational experiments

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    A computational model of the processes involved in multispectral remote sensing and data classification is developed as a tool for designing smart sensors which can process, edit, and classify the data that they acquire. An evaluation of sensor system performance and design tradeoffs involves classification rates and errors as a function of number and location of spectral channels, radiometric sensitivity and calibration accuracy, target discrimination assignments, and accuracy and frequency of compensation for imaging conditions. This model provides a link between the radiometric and statistical properties of the signals to be classified and the performance characteristics of electro-optical sensors and data processing devices. Preliminary computational results are presented which illustrate the editing performance of several remote sensing approaches

    Field inoculation of bread wheat with Rhizophagus irregularis under organic farming: variability in growth response and nutritional uptake of eleven old genotypes and a modern variety.

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    Arbuscular mycorrhizal fungi (AMF) promote crop growth and yield by increasing N and P uptake and disease resistance, but the role of field AMF inoculation on the uptake of micronutrients, such as Fe and Zn, and accumulation in plant edible portions is still not clarified. Therefore, we studied the eect of field inoculation with Rhizophagus irregularis in an organic system on 11 old genotypes and a modern variety of bread wheat. Inoculation increased root colonization, root biomass and shoot Zn concentration at early stage and grain Fe concentration at harvest, while it did not modify yield. Genotypes widely varied for shoot Zn concentration at early stage, and for plant height, grain yield, Zn and protein concentration at harvest. Inoculation dierentially modified root AMF community of the genotypes Autonomia B, Frassineto and Bologna. A higher abundance of Rhizophagus sp., putatively corresponding to the inoculated isolate, was only proved in Frassineto. The increase of plant growth and grain Zn content in Frassineto is likely linked to the higher R. irregularis abundance. The AMF role in increasing micronutrient uptake in grain was proved. This supports the introduction of inoculation in cereal farming, if the variable response of wheat genotypes to inoculation is considered

    Uterine artery Doppler evaluation in twin pregnancies at 11+0 TO 13+6 weeks of gestation

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