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Velev, Gueorgui

Publications and source records attributed to Velev, Gueorgui.

Magnetic and Mechanical Analysis of a Large Aperture 15 T Cable Test Facility Dipole Magnet

The US Department of Energy (DOE) Office of Science (SC), is funding a large bore “Cable Test Facility Magnet” for testing advanced cables and inserts in high transverse field. This is a joint effort between the Office of High Energy Physics (HEP) and the Office of Fusion Energy Sciences (FES). The background field magnet for this facility is being developed at Lawrence Berkeley National Laboratory (LBNL) while the cryostat and test facility will be located and operated by Fermi National Accelerator Laboratory (FNAL). The Nb 3 Sn dipole magnet, which will provide the transverse background field, is designed to generate a field of 15 T in a 100 × 150 mm bore at 1.9 K. The conceptual design of a block-type dipole with flared ends and a structure based on key-and-bladder technology will be introduced. The results of the magnetic and mechanical analysis will be presented.

43 PARTICLE ACCELERATORS↗

Conceptual Design of DUNE Near Detector Superconducting Magnet System

The Deep Underground Neutrino Experiment (DUNE) has formed a near detector design group (NDDG) tasked with delivering a CDR by the end of 2019. The DUNE Near Detectors will be housed in an underground hall on the Fermilab site. The two main detector systems are a liquid argon detector and a high-pressure gas time projection chamber (HPgTPC). The HPgTPC requires a magnet that generates a 0.5 T solenoidal magnetic field in a large volume of 6 m diameter, and 5 m length. Herein, we present a superconducting magnet system design. We investigated: an open air core magnet with three coils, and a five coils system having two active fringe field shielding coils. Coils positions were optimized to obtain the specified field homogeneity in the magnet good field region, while minimizing the Lorentz forces and the superconductor volume. We discuss the magnetic, mechanical, and thermal conceptual designs.

43 PARTICLE ACCELERATORS↗

The Application of Coordination to Magnetic Measurement Automation: An SSW System Example

Magnetic measurements are an integral part of the development cycle of accelerator magnets, a part which provides necessary feedback to drive design and manufacturing improvements and corrections. Automation of these measurements allows for reduction of human errors and reproducibility of measurements. Realization of automation via coordination that is separated at the architectural level from the functional code provides flexibility in defining measurement procedures and substantial extensibility. The described Single Stretched Wire (SSW) system herein is an implementation of such a solution with the use of a component-based framework designed to build a family of measurement systems.

43 PARTICLE ACCELERATORS↗

Magnetic Measurement With Single Stretched Wire Method on SuperKEKB Final Focus Quadrupoles

Superconducting-final-focus-quadrupole magnet system (QCS) were installed on an interaction region (IR) of SuperKEKB on Feb. 2017. The QCS consists of eight quadrupole magnets and four compensation solenoids; these magnets are contained in the two cryostats and are installed into Belle II detector which generates a solenoid field of 1.5 T. We determined the quadrupole centers with respect to accelerator beam lines with a single stretched wire (SSW) method. Here the results of the magnetic measurement with SSW are presented.

43 PARTICLE ACCELERATORS↗

Fermilab Superconducting Nb₃Sn High Field Magnet R&D Program

Magnets based on the modern Nb₃Sn conductor are the main candidates for future high-energy hadron colliders. Fermilab as part of the U.S. MDP executes an extensive R&D program on these high-field magnets. This program includes basic conductor and material R&D, quench per-formance studies, and building a meter-long high-field demonstrator. This paper summarizes the current status of the program including its recent results.

43 PARTICLE ACCELERATORS↗

Measurements of Decay and Snapback in Nb₃Sn Accelerator Magnets at Fermilab

In recent years, Fermilab has been executing an inten-sive R&D program on Nb₃Sn accelerator magnets. This program has included dipole and quadrupole models and demonstrators for various programs and projects, including the HL-LHC accelerator upgrade project. A systematic study of the field decay and snapback during the injection portion of a simulated accelerator cycle was executed at the Fermilab Magnet Test Facility. This paper summarizes the recent measurements of the MQXFS1 short quadrupole model and discusses the results of some previously measured Nb₃Sn magnets at CERN

43 PARTICLE ACCELERATORS↗

Measurements of Dynamic Effects in FNAL 11 T Nb 3 Sn Dipole Models

Fermilab, in collaboration with CERN, has developed a twin-aperture 11 T Nb 3 Sn dipole suitable for the high-luminosity LHC upgrade. During 2012-2014, a 2-m long single-aperture dipole demonstrator and three 1-m long single-aperture dipole models were fabricated by FNAL and tested at its Vertical Magnet Test Facility. Collared coils from two of the 1-m long models were then used to assemble the first twin-aperture dipole demonstrator. This magnet had extensive testing in 2015-2016, including quench performance, quench protection, and field quality studies. Here, this paper reports the results of measurements of persistent current effects in the single-aperture and twin-aperture 11 T Nb 3 Sn dipoles and compares them with similar measurements in previous NbTi magnets

43 PARTICLE ACCELERATORS↗

Summary of Test Results of MQXFS1—The First Short Model 150 mm Aperture Nb 3 Sn Quadrupole for the High-Luminosity LHC Upgrade

The development of Nb 3 Sn quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC interaction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb3Sn magnets boosting the LHC program of having 10-fold increase in integrated luminosity after the foreseen upgrades. Previously, LARP conducted successful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated a strong performance at Fermilab's vertical magnet test facility reaching the LHC operating limits. This paper presents the latest results from MQXFS1 tests with changed prestress levels. The overall magnet performance, including quench training and memory, ramp rate, and temperature dependence, is also summarized.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Performance of the First Short Model 150-mm-Aperture Nb3Sn Quadrupole MQXFS for the High-Luminosity LHC Upgrade

LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb 3Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-Aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 10 34 cm -2 s -1 or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-Aperture Nb3Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. Here, this paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Status of 11 T 2-in-1 Nb$_3$Sn Dipole Development for LHC

The LHC upgrade plans foresee installation of additional collimators in the LHC lattice. To provide the necessary longitudinal space for these collimators, shorter and stronger Nb3Sn dipoles compatible with the LHC lattice and main systems could be used. This paper describes the design and status of the twin-aperture Nb3Sn dipole being developed by FNAL and CERN for the LHC, and reports test results of two collared coils to be used in the first 1 m long twin-aperture dipole model.

43 PARTICLE ACCELERATORS↗

Top physics at CDF

Top quark physics is one of the most important successes of the concluding Tevatron program. In this paper, a summary of the most recent measurements of top quark properties, including the mass and its 2011 average, will be presented. Some common techniques and discussion of major systematic uncertainties for top measurements will also be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗