45080627
COLLIMATEUR INTEGRATION AND INSTALLATION EXAMPLE OF ONE OBJECT TO BE INSTALLED IN THE LHC
The collimation system is a vital part of the LHC project, protecting the accelerator against unavoidable regular and irregular beam loss. About 80 collimators will be installed in the machine before the first run. Two insertion regions are dedicated to collimation and these regions will be among the most radioactive in the LHC. The space available in the collimation regions is very restricted, it was therefore important to ensure that the 3-D integration of these areas of the LHC tunnel would allow straightforward installation of collimators and also exchange of collimators under the remote handling constraints imposed by high radiation levels. The paper describes the 3D integration studies and verifications of the collimation regions combining the restricted space available, the dimensions of the different types of collimators and the space needed for transport and handling. The paper explains how installation has been planned and carried out taking into account the handling
55572949
CRITICAL HALO LOSS LOCATIONS IN THE LHC
Results of simulations with all movable elements of the LHC collimation system [1] are discussed for various operation modes. Compared to previous results, the placing of additional collimators reduced the beam losses by a factor 10 in the ideal machine case, i.e. nominal collimators settings for both 450 GeV and 7 TeV beam energies. First results for Beam 2 are also reviewed. The sensitivity of the system to free orbit oscillations is addressed. These results show that it is sufficient to use a limited number of beam loss monitors (BLMs) for the setup and optimization of the LHC Collimation System.
55454565
THE FINAL COLLIMATION SYSTEM FOR THE LHC
The LHC collimation system has been re-designed over in order to address the unprecedented challenges that are faced with the 360 MJ beams at 7 TeV. The layout of the LHC has now been frozen and a final approach for collimation and cleaning has been adopted. In total 132 pure collimator locations have been reserved in the two LHC rings and can be installed in a phased approach. Up to 88 collimators of five different types will be available for initial beam operation. The system has been fully optimized for avoiding beam-induced quenches of superconducting magnets and for sufficient survival of beamline components against radioactive dose. The phased approach for LHC collimation is described, the various collimators and their functionalities are explained, and the expected system performance is summarized. Large Hadron Collider Project
107656092
Results of the studies on energy deposition in IR6 superconducting magnets from continuous beam loss on the TCDQ system
SummaryA single sided mobile graphite diluter block TCDQ, in combination with a two-sidedsecondary collimator TCS and an iron shield TCDQM, will be installed in front of thesuperconducting quadrupole Q4 magnets in IR6, in order to protect it and other downstreamLHC machine elements from destruction in the event of a beam dump that is not synchronisedwith the abort gap. The TCDQ will be positioned close to the beam, and will intercept theparticles from the secondary halo during low beam lifetime. Previous studies [1-4] haveshown that the energy deposited in the Q4 magnet coils can be close to or above the quenchlimit. In this note the results of the latest FLUKA energy deposition simulations for Beam 2are described, including an upgrade possibility for the TCDQ system with an additionalshielding device. The results are discussed in the context of the expected performance levelsfor the different phases of LHC operation. 1. Introduction The LHC beam dumping system includes a single sided mobile diluter block TCDQ [5],consisting of two blocks namely TCDQA and TCDQB, in combination with a secondarycollimator TCS and an iron shield TCDQM [6], installed in front of the superconductingquadrupole Q4 magnet in IR6, in order to protect it and other LHC machine elements fromdestruction in the event of a beam dump that is not synchronised with the abort gap [7]. TheTCDQ element should protect the LHC from damage from swept bunches under all conditions,in particular the arc aperture at 450 GeV, the low-beta triplet aperture and the tungsten tertiarycollimators at 7 TeV. The TCDQ must also prevent quenches of Q4, arising from spuriousparticles in the abort gap during a normal beam dump, and from particles lost from the beamhalo during regular operation.The two-jawed TCS collimator is located immediately after the TCDQ to precisely definethe horizontal beam position and to achieve higher precision collimation of secondary haloparticles from both sides. The TCS will receive a potentially high load from the secondary haloin the event of low beam lifetime. The nominal settings of the TCDQ and TCS are assumed tobe 8 and 7 s
17929707
Evaluation of Beam Losses And Energy Deposition for a Possible Phase II Design for LHC Collimation
The Large Hadron Collider (LHC) beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.
2156470
Performance reach of the "phase 1" LHC collimation system
State-of-the-art tracking tools have been developed for detailed LHC collimation and beam loss studies. This includes full chromatic treatment of both beam lines and error models. This paper reviews the main results on the performance reach of the multi-stage LHC collimation system that is being installed in the LHC. Limitations on the allowed proton loss rates and the stored intensity can be derived from the comparison of local losses with estimated quench limits for the superconducting magnets. The origins of the cleaning-related performance limitations are presented and possible improvements are discussed.
123670423
A single solution to the atmospheric and solar neutrino anomalies
Abstract We reconsider ν e - ν μ mixing as a solution for the low energy atmospheric neutrino anomaly, with δm 2 in the range (0.5−1.4)× 10 −2 eV 2 and sin 2 (2 θ ) near 0.8, and point out that it may provide a solution to the solar neutrino problem as well. This two-family vacuum oscillation solution is the simplest viable explanation of both phenomena. We consider the theoretical and experimental implications of this scenario, and another simple scenario involving three flavor mixing, and note that the new round of neutrino experiments will test these hypotheses.
119095759
Searching for Dark Matter at the LHC with a Mono-Z
We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, $\chi$, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process $q\bar{q} -> \chi\chi Z$ in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that reconstruct to the invariant mass of the Z, and large amounts of missing transverse energy. Being a purely electroweak signal, QCD and other Standard Model backgrounds are relatively easily removed with modest selection cuts. We compare the signal to Standard Model backgrounds and demonstrate that, even for conservative cuts, there exist regions of parameter space where the signal may be clearly visible above background in future LHC data, allowing either new discovery potential or the possibility of supplementing information about the dark sector beyond that available from other observable channels.
124595157
AN OVERVIEW OF THE HIGGS SECTOR WITH SPECULATION
14054232
An evaluation of the exposure in nadir observation of the JEM-EUSO mission
We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth's nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. The results are based on studies of the expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of clouds and different types of background light. We show that the annual exposure is about one order of magnitude higher than those of the presently operating ground-based observatories.
119254616
Neutrino Oscillations from Cosmic Sources: A Nu Window to Cosmology
Neutrino astrophysics promises a wealth of information about neutrinos and the history of the universe through which they have traveled. In this letter, we extend the standard neutrino qoscillation discussion to neutrinos propagating through expanding curved space. This extension introduces a new cosmological parameter in the oscillation phase. The new parameter ℐ records cosmic history in much the same manner as the redshift variable z or the apparent luminosity distance DL. Measuring ℐ through neutrino oscillations may help to determine cosmological parameters and distinguish between different cosmologies.