arXiv subjects

V. V. Kashikhin

Publications and source records attributed to V. V. Kashikhin.

At least 19 recordsLinked to original sources

arXiv2026

Critical transverse compressive stresses of straight and bent CORC$^\circledR$ wires with and without impregnation

CORC$^\circledR$ wires are a promising superconductor for accelerator magnet applications. While their excellent uniaxial tensile properties have been well established, potential degradation under transverse compression remains a significant concern for accelerator magnets, in which transverse compression is a primary stress experienced by superconductors. To evaluate the critical transverse compressive stresses of ReBCO conductors, we developed an experimental system that enables testing of samples both with and without impregnation in liquid nitrogen. Furthermore, because bending strain induced during coil winding may influence the critical compressive response of CORC$^\circledR$ wires, the apparatus was also modified to allow testing under the bending condition. In this study tests were conducted for five configurations: (1) straight wires without impregnation, (2) bent wires without impregnation, (3) straight wires with Stycast 2850 FT impregnation, (4) bent wires with Stycast 2850 FT impregnation, and (5) bent wires impregnated with paraffin wax. The transverse pressures corresponding to 3% and 5% reductions in the critical current are reported. The effects of wire bending and impregnation on the critical transverse pressure are analyzed, and the implications for transverse stress levels in accelerator magnet conductors are discussed.

physics.acc-ph↗

arXiv2024

Re-assembly and test of a COMB dipole magnet with STAR wires

Rare-Earth Barium Copper Oxide (REBCO) coated conductors are an attractive option for application in high field accelerator magnets due to their high critical field and the convenience of fabrication without heat treatment compared to some other superconductors. A small REBCO accelerator magnet was previously fabricated and tested in liquid nitrogen, demonstrating over 90% critical current retention in the coils. This paper describes the magnet re-assembly with a different support structure and its test in liquid helium at 1.8-4.5 K. The magnet quench history along with the instrumentation data is presented and discussed.

physics.acc-ph↗

arXiv2023

Accelerator Magnet Development Based on COMB Technology with STAR Wires

This paper reports progress in the development of COMB magnet technology with STAR wires. A two-layer dipole magnet with 60 mm clear bore has been recently fabricated and tested in liquid nitrogen. The purpose of the test was to determine what kind of critical current degradation occurs in the process of winding the STAR wire into the COMB structure.

physics.acc-ph↗

arXiv2023

Conceptual design of 20 T hybrid accelerator dipole magnets

Hybrid magnets are currently under consideration as an economically viable option towards 20 T dipole magnets for next generation of particle accelerators. In these magnets, High Temperature Superconducting (HTS) materials are used in the high field part of the coil with so-called insert coils, and Low Temperature Superconductors (LTS) like Nb3Sn and Nb-Ti superconductors are used in the lower field region with so-called outsert coils. The attractiveness of the hybrid option lays on the fact that, on the one hand, the 20 T field level is beyond the Nb3Sn practical limits of 15-16 T for accelerator magnets and can be achieved only via HTS materials; on the other hand, the high cost of HTS superconductors compared to LTS superconductors makes it advantageous exploring a hybrid approach, where the HTS portion of the coil is minimized. We present in this paper an overview of different design options aimed at generating 20 T field in a 50 mm clear aperture. The coil layouts investigated include the Cos-theta design (CT), with its variations to reduce the conductor peak stress, namely the Canted Cos-theta design (CCT) and the Stress Management Cos-theta design (SMCT), and, in addition, the Block-type design (BL) including a form of stress management and the Common-Coil design (CC). Results from a magnetic and mechanical analysis are discussed, with particular focus on the comparison between the different options regarding quantity of superconducting material, field quality, conductor peak stress, and quench protection.

physics.acc-ph↗

arXiv2022

Critical problems of energy frontier Muon Colliders: optics, magnets and radiation

This White Paper brings together our previous studies on a Muon Collider (MC) and presents a design concept of the 6 TeV MC optics, the superconducting (SC) magnets, and a preliminary analysis of the protection system to reduce magnet radiation loads as well as particle backgrounds in the detector. The SC magnets and detector protection considerations impose strict limitations on the lattice choice, hence the design of the collider optics, magnets and Machine Detector Interface (MDI) are closely intertwined. As a first approximation we use the Interaction Region (IR) design with beta-star=3 mm, whereas for the arcs we re-scale the arc cell design of the 3 TeV MC. Traditional cos-theta coil geometry and Nb3Sn superconductor were used to provide field maps for the analysis and optimization of the arc lattice and IR design, as well as for studies of beam dynamics and magnet protection against radiation. The stress management in the coil will be needed to avoid large degradation or even damage of the brittle SC coils. In the assumed IR designs, the dipoles close to the Interaction Point (IP) and tungsten masks in each IR (to protect magnets) help reducing background particle fluxes in the detector by a substantial factor. The tungsten nozzles in the 6 to 600 cm region from the IP, assisted by the detector solenoid field, trap most of the decay electrons created close to the IP as well as most of the incoherent electron-positron pairs generated in the IP. With sophisticated tungsten, iron, concrete and borated polyethylene shielding in the MDI region, the total reduction of background loads by more than three orders of magnitude can be achieved.

physics.acc-ph↗

arXiv2022

Solving Critical Problems of the Muon Collider Higgs Factory: Optics, Magnets and their Protection, Detector Backgrounds

A low-energy medium-luminosity Muon Collider (MC) is being studied as a possible Higgs Factory (HF). Electrons from muon decays will deposit more than 300 kW in superconducting magnets of the HF collider ring. This imposes significant challenges to superconducting (SC) magnets used in the MC storage ring (SR) and interaction regions (IR). Magnet designs are proposed which provide high operating gradient and magnetic field in a large aperture to accommodate the large size of muon beams (due to low beta*), as well as a cooling system to intercept the large heat deposition from the showers induced by decay electrons. The distribution of heat deposition in the MC SR lattice elements requires large-aperture magnets in order to accommodate thick high-Z absorbers to protect the SC coils. Based on the developed MARS15 model and intensive simulations, a sophisticated radiation protection system was designed for the collider SR and IR to bring the peak power density in the superconducting coils below the quench limit and reduce the dynamic heat deposition in the cold mass by a factor of 100. The system consists of tight tungsten masks in the magnet interconnect regions and elliptical tungsten liners in the magnet aperture optimized individually for each magnet. These also reduce the background particle fluxes in the collider detector.

physics.acc-ph↗

arXiv2022

White Paper on Leading-Edge technology And Feasibility-directed (LEAF) Program aimed at readiness demonstration for Energy Frontier Circular Colliders by the next decade

In this White Paper for the Snowmass 2021 Process, we propose the establishment of a magnet Leading-Edge technology And Feasibility-directed Program (LEAF Program) to achieve readiness for a future collider decision on the timescale of the next decade. The LEAF Program would rely on, and be synergetic with, generic R&D efforts presently covered - in the US - by the Magnet Development Program (MDP), the Conductor Procurement and R&D (CPRD) Program and other activities in the Office of HEP supported by Early Career Awards (ECA) or Lab Directed R&D (LDRD) funds. Where possible, ties to synergetic efforts in other Offices of DOE or NSF are highlighted and suggested as wider Collaborative efforts on the National scale. International efforts are also mentioned as potential partners in the LEAF Program. We envision the LEAF Program to concentrate on demonstrating the feasibility of magnets for muon colliders as well as next generation high energy hadron colliders, pursuing, where necessary and warranted by the nature of the application, the transition from R&D models to long models/prototypes. The LEAF Program will naturally drive accelerator-quality and experiment-interface design considerations. LEAF will also concentrate, where necessary, on cost reduction and/or industrialization steps.

physics.acc-ph↗

arXiv2018

The Higgs Factory Muon Collider Superconducting Magnets and Their Protection Against Beam Decay Radiation

Low-energy medium-luminosity Muon Collider (MC) is being studied as a possible Higgs Factory (HF). Electrons from muon decays will deposit more than 300 kW in superconducting magnets of the HF collider ring. This imposes significant challenges to superconducting (SC) magnets used in the MC storage ring (SR) and interaction regions (IR). The magnet designs are proposed which provide high operating gradient and magnetic field in a large aperture to accommodate the large size of muon beams due to low \b{eta}* as well as the cooling system to intercept the large heat deposition from the showers induced by decay electrons. Specific distribution of heat deposition in the lattice elements MC SR requires large aperture magnets to accommodate thick high-Z absorbers to protect the SC coils. Based on the developed MARS15 model and intense simulations, a sophisticated radiation protection system was designed for the collider SR and IR to bring the peak power density in the superconducting coils below the quench limit and reduce the dynamic heat deposition in the cold mass by a factor of 100. The system consists of tight tungsten masks in the magnet interconnect regions and elliptical tungsten liners in magnet aperture optimized for each magnet. It also reduces the background particle fluxes in the collider detector.

physics.acc-ph↗

arXiv2015

Mu2e Technical Design Report

The Mu2e experiment at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the preliminary design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-2 approval.

physics.ins-det↗

arXiv2014

Storage Ring And Interaction Region Magnets For A μ+μ- Higgs Factory

A low-energy Muon Collider (MC) offers unique opportunities to study the recently found Higgs boson. However, due to a relatively large beam emittance with moderate cooling in this machine, large-aperture high- field superconducting (SC) magnets are required. The magnets need also an adequate margin to operate at a large radiation load from the muon decay showers. General specifications of the SC dipoles and quadrupoles for the 125 GeV c.o.m. Higgs Factory with an average luminosity of ~2x10**31 cm-2s-1 are formulated. Magnet conceptual designs and parameters are reported. The impact of the magnet fringe fields on the beam dynamics as well as the IR and lattice magnet protection from radiation are also reported and discussed.

physics.acc-ph↗

arXiv2012

Mu2e Conceptual Design Report

Mu2e at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the conceptual design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-1 approval, which was granted July 11, 2012.

physics.ins-det↗

arXiv2012

Muon collider interaction region design

Design of a muon collider interaction region (IR) presents a number of challenges arising from low β* < 1 cm, correspondingly large beta-function values and beam sizes at IR magnets, as well as the necessity to protect superconducting magnets and collider detectors from muon decay products. As a consequence, the designs of the IR optics, magnets and machine-detector interface are strongly interlaced and iterative. A consistent solution for the 1.5 TeV c.o.m. muon collider IR is presented. It can provide an average luminosity of 1034 cm-2s-1 with an adequate protection of magnet and detector components.

physics.acc-ph↗

arXiv2012

Radiation effects in a muon collider ring and dipole magnet protection

The requirements and operating conditions for a Muon Collider Storage Ring (MCSR) pose significant challenges to superconducting magnets. The dipole magnets should provide a high magnetic field to reduce the ring circumference and thus maximize the number of muon collisions during their lifetime. One third of the beam energy is continuously deposited along the lattice by the decay electrons at the rate of 0.5 kW/m for a 1.5-TeV c.o.m. and a luminosity of 1034 cm-2s-1. Unlike dipoles in proton machines, the MCSR dipoles should allow this dynamic heat load to escape the magnet helium volume in the horizontal plane, predominantly towards the ring center. This paper presents the analysis and comparison of radiation effects in MCSR based on two dipole magnets designs. Tungsten masks in the interconnect regions are used in both cases to mitigate the unprecedented dynamic heat deposition and radiation in the magnet coils.

physics.acc-ph↗

arXiv2012

Radiation and thermal analysis of production solenoid for Mu2e experimental setup

The Muon-to-Electron (Mu2e) experiment at Fermilab, will seek the evidence of direct muon to electron conversion at the sensitivity level where it cannot be explained by the Standard Model. An 8-GeV 25-kW proton beam will be directed onto a tilted gold target inside a large-bore superconducting Production Solenoid (PS) with the peak field on the axis of ~5T. The negative muons resulting from the pion decay will be captured in the PS aperture and directed by an S-shaped Transport Solenoid towards the stopping target inside the Detector Solenoid. In order for the superconducting magnets to operate reliably and with a sufficient safety margin, the peak neutron flux entering the coils must be reduced by 3 orders of magnitude that is achieved by means of a sophisticated absorber placed in the magnet aperture. The proposed absorber, consisting of W- and Cu-based alloy parts, is optimized for the performance and cost. Results of MARS15 simulations of energy deposition and radiation are reported. The results of the PS magnet thermal analysis, coordinated with the coil cooling scheme, are reported as well for the selected absorber design.

physics.acc-ph↗

arXiv2012

Muon Collider interaction region and machine-detector interface design

One of the key systems of a Muon Collider (MC) - seen as the most exciting option for the energy frontier machine in the post-LHC era - is its interaction region (IR). Designs of its optics, magnets and machine-detector interface are strongly interlaced and iterative. As a result of recent comprehensive studies, consistent solutions for the 1.5-TeV c.o.m. MC IR have been found and are described here. To provide the required momentum acceptance, dynamic aperture and chromaticity, an innovative approach was used for the IR optics. Conceptual designs of large-aperture high-field dipole and high-gradient quadrupole magnets based on Nb3Sn superconductor were developed and analyzed in terms of the operating margin, field quality, mechanics, coil cooling and quench protection. Shadow masks in the interconnect regions and liners inside the magnets are used to mitigate the unprecedented dynamic heat deposition due to muon decays (~0.5 kW/m). It is shown that an appropriately designed machine-detector interface (MDI) with sophisticated shielding in the detector has a potential to substantially suppress the background rates in the MC detector.

physics.acc-ph↗

arXiv2012

Conceptual designs of dipole magnet for muon collider ring

Conceptual designs of a superconducting dipole magnet for a Storage Ring of a Muon Collider with a 1.5 TeV center of mass (c.o.m.) energy and an average luminosity of 10 34 cm-2s-1 are presented. In contrast to proton machines, the dipoles for the Muon Collider should be able to handle ~0.5 kW/m of dynamic heat load from the muon beam decays. The magnets are based on Nb3Sn superconductor and designed to provide an operating field of 10 T in the 20-mm aperture with the critical current margin required for reliable machine operation. The magnet cross-sections were optimized to achieve the best possible field quality in the aperture occupied by beams. The developed mechanical structures provide adequate coil prestress and support at the maximum level of Lorentz forces in the coil. Magnet parameters are reported and compared with the requirements.

physics.acc-ph↗

arXiv2012

Muon collider interaction region design

Design of a muon collider interaction region (IR) presents a number of challenges arising from low β * < 1 cm, correspondingly large beta-function values and beam sizes at IR magnets, as well as the necessity to protect superconducting magnets and collider detectors from muon decay products. As a consequence, the designs of the IR optics, magnets and machine-detector interface are strongly interlaced and iterative. A consistent solution for the 1.5 TeV c.o.m. muon collider IR is presented. It can provide an average luminosity of 1034 cm-2s-1 with an adequate protection of magnet and detector components.

physics.acc-ph↗

arXiv2012

Magnet designs for muon collider ring and interactions regions

Conceptual designs of superconducting magnets for the storage ring of a Muon Collider with a 1.5 TeV c.o.m. energy and an average luminosity of 10 34 cm-2s-1 are presented. All magnets are based on Nb3Sn superconductor and designed to provide an adequate operating field/field gradient in the aperture with the critical current margin required for reliable magnet operation in the machine. Magnet cross-sections were optimized to achieve the accelerator field quality in the magnet aperture occupied with beams. The magnets and corresponding protective measures are designed to handle about 0.5 kW/m of dynamic heat load from the muon beam decays. Magnet parameters are reported and compared with the requirements.

physics.acc-ph↗