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Energy deposited in the high luminosity inner triplets of the LHC by collision debris

Description: The 14 TeV center of mass proton-proton collisions in the LHC produce not only debris interesting for physics but also showers of particles ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of this contribution to the heat, that has to be transported by the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC base-line are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the consolidation of the calculations, a dedicated comparative study of these two codes was performed for a reduced setup.
Date: June 1, 2008
Creator: Wildner, E.; /CERN; Broggi, F.; /INFN, Milan; Cerutti, F.; Ferrari, A. et al.
Partner: UNT Libraries Government Documents Department

Implementation of Double-Waist Chicane Optics in SPEAR3

Description: The SPEAR3 accelerator upgrade opened up two 7.6m racetrack straights in the magnet lattice. In one of these straights, we recently added a magnetic chicane to separate two insertion device (ID) beam lines by 10mrad. A quadrupole triplet in the center creates a ''double focus'' optics with {beta}y = 1.6m at the middle of each ID, hence the term ''double-waist chicane''. The new optics also reduced {beta}y in the four matching straights adjacent to the racetrack straights to 2.5m. In this paper, we outline design features of the optics and physical implementation of the lattice.
Date: August 16, 2006
Creator: Corbett, J.; Cornacchia, M.; Dao, T.; Dell'Orco, D.; Rafael, F.; Harrington, D. et al.
Partner: UNT Libraries Government Documents Department

Proposal to Study Dilepton Neutrino Interactions with the Triplet Quadrupole Beam, the Phase 1 EMI, and the 15' Bubble Chamber Filled with a H-Ne Mixture

Description: The authors propose to study dilepton neutrino events in the 15-foot bubble chamber using the quadrupole beam. The chamber is filled with at least 80% neon (15 ton fiducial target), the EMI is rearranged into 2 planes to give at least 7 absorption lengths for muon identification and give time coincidence, and the beam has a 1 millisecond spill. This will give about 150 dimuon events and 150 muon electron events per 100,000 pictures. They request 200,000 pictures.
Date: January 1, 1975
Creator: Harris, R.; Huson, F.R.; Kahn, S.; Murphy, T.; Smart, W.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Field Tolerances for the Triplet Quadrupoles of the LHC High Luminosity Lattice

Description: It has been proposed to implement the so-called Achromatic Telescopic Squeezing (ATS) scheme in the LHC high luminosity (HL) lattice to reduce beta functions at the Interaction Points (IP) up to a factor of 8. As a result, the nominal 4.5 km peak beta functions reached in the Inner Triplets (IT) at collision will be increased by the same factor. This, therefore, justifies the installation of new, larger aperture, superconducting IT quadrupoles. The higher beta functions will enhance the effects of the triplet quadrupole field errors leading to smaller beam dynamic aperture (DA). To maintain the acceptable DA, the effects of the triplet field errors must be re-evaluated, thus specifying new tolerances. Such a study has been performed for the so-called '4444' collision option of the HL-LHC layout version SLHCV3.01, where the IP beta functions are reduced by a factor of 4 in both planes with respect to a pre-squeezed value of 60 cm at two collision points. The dynamic aperture calculations were performed using SixTrack. The impact on the triplet field quality is presented.
Date: June 25, 2012
Creator: Nosochkov, Yuri; Cai, Y.; Jiao, Y.; Wang, M-H.; Fartoukh, S.; Giovannozzi, M. et al.
Partner: UNT Libraries Government Documents Department

Performance of a High Resolution Cavity Beam Position Monitor System

Description: It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than one nanometer. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 {mu}rad over a dynamic range of approximately {+-} 20 {mu}m.
Date: June 8, 2007
Creator: Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Joe; Frisch, Joe; Gronberg, Jeff et al.
Partner: UNT Libraries Government Documents Department

Field quality measurements and abalysis of the LARP technology quadrupole models

Description: One of the US-LHC accelerator research program goals is to develop and prove the design and technology of Nb{sub 3}Sn quadrupoles for an upgrade of the LHC Interaction Region (IR) inner triplets. Four 1-m long technology quadrupole models with a 90 mm bore and field gradient of 200 T/m based on similar coils and different mechanical structures have been developed. In this paper, we present the field quality measurements of the first several models performed at room temperature as well as at superfluid helium temperature in a wide field range. The measured field harmonics are compared to the calculated ones. The field quality of Nb{sub 3}Sn quadrupole models is compared with the NbTi quadrupoles recently produced at Fermilab for the first generation LHC IRs.
Date: August 1, 2007
Creator: Bossert, R.; Chlachidze, G.; DiMarco, J.; Kashikhin, V.V.; Lamm, M.; Schlabach, P. et al.
Partner: UNT Libraries Government Documents Department

Magnetic field measurements of LHC inner triplet quadrupoles fabricated at Fermilab

Description: Fermilab, as part of the US-LHC Accelerator Project, is producing superconducting low-beta quadrupole magnets for the Large Hadron Collider (LHC). These 5.5 m long magnets are designed to operate in superfluid helium at 1.9 K with a nominal gradient of 205 T/m in the 70 mm bore. Two quadrupoles separated by a dipole orbit corrector in a single cryogenic assembly comprise the Q2 optical elements of the final focus triplets in the LHC interaction regions. The field quality of the quadrupoles is measured at room temperature during construction of the cold masses as well as during cold testing of the cryogenic assembly. We summarize data from the series measurements of the magnets and discuss various topics of interest.
Date: August 1, 2006
Creator: Velev, G.V.; Bossert, R.; Carcagno, R.; DiMarco, J.; Feher, S.; Kashikhin, V.V. et al.
Partner: UNT Libraries Government Documents Department

Production and installation of the LHC low-beta triplets

Description: The LHC performance depends critically on the low-{beta}, triplets, located on either side of the four interaction points. Each triplet consists of four superconducting quadrupole magnets, which must operate reliably at up to 215 T/m, sustain extremely high heat loads and have an excellent field quality. A collaboration of CERN, Fermilab and KEK was formed in 1996 to design and build the triplet systems, and after nine years of joint effort the production has been completed in 2005. We retrace the main events of the project and present the design features and performance of the low-{beta} quadrupoles, built by KEK and Fermilab, as well as of other vital elements of the triplet. The tunnel installation of the first triplet and plans for commissioning in the LHC are also presented. Apart from the excellent technical results, the construction of the LHC low-{beta} triplets has been a highly enriching experience combining harmoniously the different competences and approaches to engineering in a style reminiscent of high energy physics experiment collaborations, and rarely before achieved in construction of an accelerator.
Date: September 1, 2005
Creator: Feher, S.; Bossert, R.; DiMarco, J.; Karppinen, M.; Kerby, J.; Kimura, N. et al.
Partner: UNT Libraries Government Documents Department

Search for New Phenomena Associated with High Energy Neutrinos Using the Quadrupole Triplet Beam

Description: The authors propose to take one million pictures of high energy neutrinos in an approximately 20% mixture of Neon and Helium using the FNAL 15 foot bubble chamber exposed to the quadrupole triplet focused neutrino beam with the EMI. Their experience in E-28A has shown that the capability of recording and analyzing high multiplicity, multiple gamma conversions, secondary neutron interactions, and high energy electrons makes this instrument uniquely useful in searching for new phenomena in neutrino interactions.
Date: January 1, 1975
Creator: Camerini, U.; Cline, D.; Fry, W.F.; von Krogh, J.; Loveless, R.; Mapp, J. et al.
Partner: UNT Libraries Government Documents Department

A 3 TeV Muon Collider Lattice Design

Description: A new lattice for 3 TeV c.o.m. energy with {beta}* = 5mm was developed which follows the basic concept of the earlier 1.5 TeV design but uses quad triplets for the final focus in order to keep the maximum magnet strength and aperture close to those in 1.5 TeV case. Another difference is employment of combined-function magnets with the goal to lower heat deposition in magnet cold mass and to eliminate bending field free regions which produce 'hot spots' of neutrino radiation that can be an issue at higher energy. The proposed lattice is shown to satisfy the requirements on luminosity, dynamic aperture and momentum acceptance.
Date: May 1, 2012
Creator: Alexahin, Y. & Gianfelice-Wendt, E.
Partner: UNT Libraries Government Documents Department

Coil Creep and Skew-Quadrupole Field Components in the Tevatron

Description: During the start-up of Run II of the Tevatron Collider program, several issues surfaced which were not present, or not seen as detrimental, during Run I. These included the repeated deterioration of the closed orbit requiring orbit smoothing every two weeks or so, the inability to correct the closed orbit to desired positions due to various correctors running at maximum limits, regions of systematically strong vertical dipole corrections, and the identification of very strong coupling between the two transverse degrees-of-freedom. It became apparent that many of the problems being experienced operationally were connected to a deterioration of the main dipole magnet alignment, and remedial actions were undertaken. However, the alignment alone was not enough to explain the corrector strengths required to handle transverse coupling. With one exception, strong coupling had generally not been an issue in the Tevatron during Run I. Based on experience with the Main Ring, the Tevatron was designed with a very strong skew quadrupole circuit to compensate any quadrupole alignment and skew quadrupole field errors that might present themselves. The circuit was composed of 48 correctors placed evenly throughout the arcs, 8 per sector, evenly placed in every other cell. Other smaller circuits were installed but not initially needed or commissioned. These smaller circuits were composed of individual skew quadrupole correctors on either side of the long straight sections. These circuits were tuned by first bringing the horizontal and vertical tunes near each other. The skew quadrupoles were then adjusted to minimize tune split, usually to less than 0.003. Initially, the main skew quad circuit (designated T:SQ) could accomplish this global decoupling with only 4% of its possible current, and the smaller circuits were not required at all. The start-up of Run Ib was complicated by what was later discovered to be a rolled triplet quadrupole ...
Date: July 11, 2011
Creator: Annala, G.; Harding, D.J.; Syphers, M.J. & /Fermilab
Partner: UNT Libraries Government Documents Department

Instrumentation status of the low-b magnet systems at the Large Hadron Collider (LHC)

Description: The low-{beta} magnet systems are located in the Large Hadron Collider (LHC) insertion regions around the four interaction points. They are the key elements in the beams focusing/defocusing process allowing proton collisions at luminosity up to 10{sup 34}cm{sup -2}s{sup -1}. Those systems are a contribution of the US-LHC Accelerator project. The systems are mainly composed of the quadrupole magnets (triplets), the separation dipoles and their respective electrical feed-boxes (DFBX). The low-{beta} magnet systems operate in an environment of extreme radiation, high gradient magnetic field and high heat load to the cryogenic system due to the beam dynamic effect. Due to the severe environment, the robustness of the diagnostics is primordial for the operation of the triplets. The hardware commissioning phase of the LHC was completed in February 2010. In the sake of a safer and more user-friendly operation, several consolidations and instrumentation modifications were implemented during this commissioning phase. This paper presents the instrumentation used to optimize the engineering process and operation of the final focusing/defocusing quadrupole magnets for the first years of operation.
Date: May 1, 2011
Creator: Darve, C.; /Fermilab; Balle, C.; Casas-Cubillos, J.; Perin, A.; Vauthier, N. et al.
Partner: UNT Libraries Government Documents Department

Beam Coupling to Optical Scale Accelerating Structures

Description: Current research efforts into structure based laser acceleration of electrons utilize beams from standard RF linacs. These beams must be coupled into very small structures with transverse dimensions comparable to the laser wavelength. To obtain decent transmission, a permanent magnet quadrupole (PMQ) triplet with a focusing gradient of 560 T/m is used to focus into the structure. Also of interest is the induced wakefield from the structure, useful for diagnosing potential accelerator structures or as novel radiation sources.
Date: March 27, 2007
Creator: Sears, C.M.; Byer, R.L.; Colby, E.R.; Cowan, B.M.; Ischebeck, R.; Lincoln, M.R. et al.
Partner: UNT Libraries Government Documents Department

Performance of a Nanometer Resolution BPM System

Description: International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on variable-length struts which allow movement in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a calibration algorithm which is immune to beam jitter. To date, we have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of +/- 20 microns. We report on the progress of these ongoing tests.
Date: April 24, 2007
Creator: Walston, S.; Chung, C.; Fitsos, P.; Gronberg, J.; /LLNL, Livermore; Meller, R. et al.
Partner: UNT Libraries Government Documents Department

Resolution of a High Performance Cavity Beam Positron Monitor System

Description: International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved--ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of +/- 20 microns.
Date: July 6, 2007
Creator: Walston, S.; Chung, C.; Fitsos, P.; Gronberg, J.; /LLNL, Livermore; Ross, M. et al.
Partner: UNT Libraries Government Documents Department

The Magnet Fiducialization Problem

Description: Magnets in accelerator beamlines have, for the most part, been made with ferromagnetic poles and traditionally these pole surfaces have been used as the references for external alignment aids, tooling balls, CERN sockets and so on. This practice assumes that the magnetic field is well-defined by the poles (which fails in the presence of saturation). It also fails in the case of superconducting magnets, which have no tangible poles. Other difficulties are well-known to those working in the field: the poles of an iron dipole magnet are never perfectly flat, or perfectly parallel. Where, then, is the magnetic mid-plane? The corresponding problem for iron quadrupoles, sextupoles etc, is that there is no unique inscribed circle that is tangent to more than three of these poles. The magnetic axis is then difficult to define. The greater the precision that is sought in the alignment, the more apparent these problems become. The answer, I believe, is to use magnetic field measurements to establish the references. Most magnets undergo some magnetic measurement before use--they certainly should--and so the opportunity is there to combine fiducialization with magnetic field definition. A substantial part of the Final Focus Test Beam program at SLAC will address this problem. Meanwhile I would like to use the work of some other SLAC colleagues to illustrate one approach. As part of the installation of the new SLD detector at the Linear Collider, a pair of superconducting triplet quadrupoles will be added as the final focusing elements before the detector. Fiducials (tooling balls) on the outside of the cryostats are referenced to the magnetic axis of the quads in a set-up as shown in Fig. 1. The probe P is a small rotating coil in a warm-bore insert in the quadrupole. Its center of rotation, X{sub p}, Y{sub p}, can be ...
Date: August 12, 2005
Creator: Harvey, A.
Partner: UNT Libraries Government Documents Department

Steady State Heat Deposits Modeling in the Nb3Sn Quadrupole Magnets for the Upgrade of the LHC Inner Triplet

Description: In hadron colliders such as the LHC, the energy deposited in the superconductors by the particles lost from the beams or coming from the collision debris may provoke quenches detrimental to the accelerator operation. In previous papers, a Network Model has been used to study the thermodynamic behavior of magnet coils and to calculate the quench levels in the LHC magnets for expected beam loss profiles. This model was subsequently used for thermal analysis and design optimization of Nb{sub 3}Sn quadrupole magnets, which LARP (US LHC Accelerator Research Program) is developing for possible use in the LHC luminosity upgrade. For these new magnets, the heat transport efficiency from the coil to the helium bath needs to be determined and optimized. In this paper the study of helium cooling channels and the heat evacuation scheme are presented and discussed.
Date: September 1, 2011
Creator: Bocian, D.; Ambrosio, G.; Felice, H.; Barzi, E.; Bossert, R.; Caspi, S. et al.
Partner: UNT Libraries Government Documents Department