Development of Radiation-Tolerant HTS Magnet for Muon Production Solenoid

Toru Ogitsu,Masami Iio,Makoto Yoshida,Naritoshi Kawamura

doi:10.3390/instruments4040030

Toru Ogitsu, Masami Iio + Show 2 more

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https://doi.org/10.3390/instruments4040030

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Journal: Instruments	Publication Date: Oct 12, 2020
Citations: 1	License type: CC BY 4.0

Affiliation: High Energy Accelerator Research Organization

Abstract

Superconducting magnets are widely used in accelerator science applications. Muon production solenoids are applications that have recently attracted considerable public attention, after the approval of muon-related physics projects such as coherent muon to electron transition or muon-to-electron-conversion experiments. Based on its characteristics, muon production solenoids tend to be subjected to high radiation exposure, which results in a high heat load being applied to the solenoid magnet, thus limiting the superconducting magnet operation, especially for low-temperature superconductors such as niobium titanium alloy. However, the use of high-temperature superconductors may extend the operation capabilities owing to their functionality at higher temperatures. This study reviews the characteristics of high temperature superconductor magnets in high-radiation environments and their potential for application to muon production solenoids.

Highlights

A muon production solenoid magnet generates a magnetic field that captures charged secondary particles, such as pions or muons, which are produced by a production target
The most extreme case is the production solenoids planned for muon rare decay experiments such as the coherent muon to electron transition (COMET) [1] experiment at the Japan
The high-temperature superconductors (HTS) version is proposed as an option for the NbTi cable in conduit design developed at National Superconducting Cyclotron Laboratory (NSCL) [20] to reduce the cryogenic operation cost by increasing the operation temperature to approximately 50 K instead of 4 K

Summary

Introduction

A muon production solenoid magnet generates a magnetic field that captures charged secondary particles, such as pions or muons, which are produced by a production target. In order to achieve high-efficiency muon production, the solenoid should be placed near the target, resulting in high radiation exposure. The most extreme case is the production solenoids planned for muon rare decay experiments such as the coherent muon to electron transition (COMET) [1] experiment at the Japan. Proton Accelerator Research Complex (J-PARC) Japan, or the muon-to-electron-conversion (Mu2e) experiment [2] at the Fermi National Accelerator Laboratory (FNAL) U.S.A. Proton Accelerator Research Complex (J-PARC) Japan, or the muon-to-electron-conversion (Mu2e) experiment [2] at the Fermi National Accelerator Laboratory (FNAL) U.S.A Both the production solenoids, which are wound from the low-temperature superconductors (LTS), instrument the production target inside its aperture, resulting in a large aperture with thick radiation shielding. The power of the primary proton beam that hits the target is limited to 56 kW [5]

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