Trajectory Correction of the LHC Injection Transfer Lines TI 2 and TI 8

The LHC injection transfer lines TI 2 and TI 8 will transport very intense high-energy small-emittance proton beams over considerable distances. The relatively tight aperture requires a precise control of the trajectory. A detailed analysis of the trajectory excursions to be expected in the presence of various imperfections has been carried out. To stay within the given aperture a correction scheme is proposed in which two adjacent short straight sections out of every four are equipped with correctors. For both lines together this scheme requires 110 corrector elements. The maximum deflection per corrector remains below 65Ýmrad. Corrector magnets and power supplies will be recuperated from LEP and adapted to their new function. The beam position monitors will use button-type electrodes which can also be recovered from LEP

Time-dependent local Green's operator and its applications to manganites

An algorithm is presented to calculate the electronic local time-dependent Green's operator for manganites-related hamiltonians. This algorithm is proved to scale with the number of states $N$ in the Hilbert-space to the 1.55 power, is able of parallel implementation, and outperforms computationally the Exact Diagonalization (ED) method for clusters larger than 64 sites (using parallelization). This method together with the Monte Carlo (MC) technique is used to derive new results for the manganites phase diagram for the spatial dimension D=3 and half-filling on a 12x12x12 cluster (3456 orbitals). We obtain as a function of an insulating parameter, the sequence of ground states given by: ferromagnetic (FM), antiferromagnetic AF-type A, AF-type CE, dimer and AF-type G, which are in remarkable agreement with experimental results.Comment: 9 pages, 11 figure

Beam transfer to and Injection into LHC

Transfer of 450 GeV protons from SPS to LHC will be carried out through two new beam transfer lines with a length of about 2.8-km per line. One beam will use the existing SPS west extraction in LSS6 from where a new line will lead to the LHC injection near intersection 2. A new fast extraction facility in SPS LSS4 is needed for the other beam line which will lead to LHC intersection 8. Economy considerations have led to the decision to use classical magnets of compact design. A lot of components will be recuperated from closed down installations. The injection systems consist of horizontally deflecting Lambertson type septum magnets and vertically deflecting kickers. A careful control of the trajectory and the preservation of the very small emittance during transfer and injection are of key importance. Construction for the transfer lines will start in 1998 to allow first injection tests in 2003. The report describes the layout and optics design and the required performance of the main components

A new concept in the design of the LHC beam dump

Recent Monte Carlo cascade simulations have shown that a reduction in the maximum of deposited energy density can be obtained by applying a uniform magnetic field over a front part of the graphite core of the LHC dump. This paper shows the effect of field strength on spatial distributions of absorbed energy and temperatures, and discusses problems to be solved when designing a suitable magnet

Protecting LHC Components Against Radiation Resulting From an Unsynchronized Beam Abort

The effect of possible accidental beam loss in the LHC on the IP5 and IP6 insertion elements is studied via realistic Monte Carlo simulations. The scenario studied is beam loss due to unsynchronized abort at an accidental prefire of one of the abort kicker modules. Simulations show that this beam loss would result in severe heating of the IP5 and IP6 superconducting (SC) quadrupoles. Contrary to the previous considerations with a stationary set of collimators in IP5, collimators in IP6 close to the cause are proposed: a movable collimator upstream of the Q4 quadrupole and a stationary one upstream of the extraction septum MSD. The calculated temperature rise in the optimal set of collimators is quite acceptable. All SC magnets are protected by these collimators against damage

Gene Expression from the ORF50/K8 Region of Kaposi's Sarcoma-Associated Herpesvirus

The ORF50 gene of Kaposi's sarcoma (KS)-associated herpesvirus, or human herpesvirus 8 (KSHV), activates viral replication and is weakly homologous to the herpesvirus family of R transactivators; therefore, the transcription and translation events from this region of KSHV are key events in viral reactivation. We demonstrate that ORF50 is expressed in a bicistronic message after induction of the viral lytic cycle. ORF50 migrated as a series of polypeptides: the major ones as 119 and 101 kDa, respectively. Using 3' rapid amplification of cDNA ends, RT-PCR, and cDNA library screening, we demonstrate that the major ORF50 transcript also encodes K8. The ORF50/K8 transcript was resistant to cyclohexamide, whereas the K8 transcript was only partially resistant to cyclohexamide at early timepoints. Both transcripts showed partial resistance after 12 h of phorbol ester induction. Using a GAL4-ORF50 fusion protein expression vector, we demonstrate that the transactivation domain of ORF50 resides within a 160-amino-acid region of the carboxyl portion of the ORF. Upstream regions of both ORF50 and K8 have basal promoter activity in KSHV-infected cells. K8, which had sequence homology to Bzip proteins, did not activate either promoter. However, both promoters were activated after cotransfection of ORF50 in BCBL-1 cells

Optical absorption and activated transport in polaronic systems

We present exact results for the optical response in the one-dimensional Holstein model. In particular, by means of a refined kernel polynomial method, we calculate the ac and dc electrical conductivities at finite temperatures for a wide parameter range of electron phonon interaction. We analyze the deviations from the results of standard small polaron theory in the intermediate coupling regime and discuss non-adiabaticity effects in detail.Comment: 7 pages, 8 figure

What did we learn from the extraction experiments with bent crystals at the CERN SPS?

The feasibility and properties of particle extraction from an accelerator by means of a bent crystal were studied extensively at the CERN SPS. The main results of the experiments are presented. This includes the evidence for multipass extraction of heavy ions. These results are compared with theoretical expectations and computer simulations

On the dynamics of coupled S=1/2 antiferromagnetic zig-zag chains

We investigate the elementary excitations of quasi one-dimensional S=1/2 systems built up from zig-zag chains with general isotropic exchange constants, using exact (Lanczos) diagonalization for 24 spins and series expansions starting from the decoupled dimer limit. For the ideal one-dimensional zig-zag chain we discuss the systematic variation of the basic (magnon) triplet excitation with general exchange parameters and in particular the presence of practically flat dispersions in certain regions of phase space. We extend the dimer expansion in order to include the effects of 3D interactions on the spectra of weakly interacting zig-zag chains. In an application to KCuCl_3 we show that this approach allows to determine the exchange interactions between individual pairs of spins from the spectra as determined in recent neutron scattering experiments.Comment: 8 pages, 9 figures; some changes, figure added; final versio