Control of field quality for the production of the main LHC dipoles

We review the warm magnetic measurements of the first four main dipole prototypes (8 apertures) and their agreement with nominal design. We then estimate the order of magnitude of the corrections that may be needed to re-center the low-order normal harmonics around the nominal values for the forthcoming series production. Correction strategies that provide the minumum impact on production schedule and costs are analysed. For the case of b3 and b5 two possibilities are considered: a variation of the shims to optimize the azimuthal length of the two coil layers, and a variation of the copper wedges of the inner layer, leaving unchanged the azimuthal coil size. For optimizing b2 and b4, we consider modifications of the shape of the ferromagnetic insert, that is placed between the collars and the yoke. Comparison between measurements and simulations of the implemented insert modifications are given and a final design is proposed. Intrinsic limits to the control of field quality during the production are discussed

Status Report on Field Quality in the Main LHC Dipoles

We give the present status of the field quality in the main LHC dipoles. Special emphasis is given to the collared coil data: a few tens of coils have been built, allowing a first analysis of the variability between producers, and estimates of the random part. Effects of the corrective actions implemented to fine tune the systematics components of low-order multipoles are presented. Correlations of collared coil data to the magnetic field measurements in operational conditions are discussed. Comparison to specifications imposed by beam dynamics allows to pin out the most critical requirements that will have to be met during the LHC dipole production

An Estimate of Multipolar Errors in the LHC Dipoles

Magnetic measurements of 60 collared coils and of 14 cryomagnets are available for the LHC dipoles. These data are used to work out an estimate of the systematic and random components of the field harmonics, in the hypothesis of a complete mixing of the manufacturers

Optimization of the Even Normal Multipole Components in the Main Dipole of the Large Hadron Collider

In this paper we discuss even multipolar components of the Large Hadron Collider dipole in relation to the manufacturing features and target values required by beam dynamics. Due to the two-in-one collar geometry, systematic components are induced by the mutual influence of the two apertures and are strongly affected by the shape of the magnetic iron yoke. In order to optimize the normal quadrupole and octupole harmonics, a new design was chosen for the ferromagnetic insert between the iron yoke and the collars. Three different insert shapes were selected and installed in a full scale prototype. The measured dependence of the even multipoles on the insert shape shows a good agreement with simulations based on a magnetostatic code. A final design of the insert has been worked out and implemented in pre-series magnets. Data relative to even multipoles in pre-series magnets are presented, both at room temperature and at the operational temperature of 1.9 K. Comparison with target values required by beam dynamics is discussed

On the evolution of decoys in plant immune systems

The Guard-Guardee model for plant immunity describes how resistance proteins (guards) in host cells monitor host target proteins (guardees) that are manipulated by pathogen effector proteins. A recently suggested extension of this model includes decoys, which are duplicated copies of guardee proteins, and which have the sole function to attract the effector and, when modified by the effector, trigger the plant immune response. Here we present a proof-of-principle model for the functioning of decoys in plant immunity, quantitatively developing this experimentally-derived concept. Our model links the basic cellular chemistry to the outcomes of pathogen infection and resulting fitness costs for the host. In particular, the model allows identification of conditions under which it is optimal for decoys to act as triggers for the plant immune response, and of conditions under which it is optimal for decoys to act as sinks that bind the pathogen effectors but do not trigger an immune response.Comment: 15 pages, 6 figure

Impact of the First Powering Cycles on the LHC Superconducting Dipole Coil Geometry

The impact of the first powering cycles on the LHC superconducting dipoles coil geometry has been investigated. Dedicated magnetic measurements have been performed to estimate the changes in the geometric component of the harmonics, caused by the last highest Lorentz force the coil has ever experienced. Several magnets have been powered at increasing current steps while the field quality has been measured to quantify the changes in geometry. The effect of the thermal cycles has been also considered as well as the systematic differences between measurements before and after the quench training. The reconstruction of the coil geometry variations is discussed in terms of continuous modes of deformation as well as single block displacements

Analysis of Warm Magnetic Measurements in a LHC Main Dipole Prototype

The data relative to the magnetic measurements at room temperature of the MBP2N1 prototype of the LHC dipole are presented. The measured field harmonics are compared to the results of the numerical model of the dipole cross section. The contribution from different effects are evaluated and compared to experimental data. Relevant quantities on the mechanical structure and on the expected field quality are worked out

Pharmacological manipulation of L-carnitine transport into L6 cells with stable overexpression of human OCTN2

Abstract.: The high-affinity Na+-dependent carnitine transporter OCTN2 (SLC22A5) has a high renal expression and reabsorbs most filtered carnitine. To gain more insight into substrate specificity of OCTN2, we overexpressed hOCTN2 in L6 cells and characterized the structural requirements of substances acting as human OCTN2 (hOCTN2) inhibitors. A 1905-bp fragment containing the hOCTN2 complete coding sequence was introduced into the pWpiresGFP vector, and L6 cells were stably transduced using a lentiviral system. The transduced L6 cells revealed increased expression of hOCTN2 on the mRNA, protein and functional levels. Structural requirements for hOCTN2 inhibition were predicted in silico and investigated in vitro. Essential structural requirements for OCTN2 inhibition include a constantly positively charged nitrogen atom and a carboxyl, nitrile or ester group connected by a 2-4-atom linker. Our cell system is suitable for studying in vitro interactions with OCTN2, which can subsequently be investigated in viv

Optical In-Situ Measurement of Relative Deformations of the LHC Main Dipole Cold Masses

The LHC cryodipoles are composed of an evacuated cryostat and a cold mass, which is cooled by superfluid helium at 1.9 K. To obey constraints imposed by beam dynamics the particle beams must be centered within the mechanical axis of the dipole with a sub-millimeter accuracy. This requires in turn that the relative displacements between the cryostat and the cold mass must be monitored with accuracy at all times. Because of the extreme environmental conditions (the displacement must be measured in vacuum and between two points at a temperature difference of about 300 degrees), no adequate existing monitoring system was found for this application. We describe here a novel optical sensor developed for our scope and we present results of measurements made during the cold test of the dipoles

APE Results of Hadron Masses in Full QCD Simulations

We present numerical results obtained in full QCD with 2 flavors of Wilson fermions. We discuss the relation between the phase of Polyakov loops and the {\bf sea} quarks boundary conditions. We report preliminary results about the HMC autocorrelation of the hadronic masses, on a $16^3 \times 32$ lattice volume, at $\beta=5.55$ with $k_{sea}=0.1570$.Comment: 3 pages, compressed ps-file (uufiles), Contribution to Lattice 9