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Title: Nonuniform radiation damage in permanent magnet quadrupoles

Abstract

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Authors:
; ; ;  [1]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
Publication Date:
OSTI Identifier:
22314418
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 36 MATERIALS SCIENCE; COLLIMATORS; LANL; LENSES; MAGNETIZATION; NEUTRONS; PERMANENT MAGNETS; PROTON BEAMS; PROTON RADIOGRAPHY; QUADRUPOLES; RADIATION EFFECTS; SPALLATION; TUNGSTEN

Citation Formats

Danly, C. R., Merrill, F. E., Barlow, D., and Mariam, F. G.. Nonuniform radiation damage in permanent magnet quadrupoles. United States: N. p., 2014. Web. doi:10.1063/1.4892803.
Danly, C. R., Merrill, F. E., Barlow, D., & Mariam, F. G.. Nonuniform radiation damage in permanent magnet quadrupoles. United States. doi:10.1063/1.4892803.
Danly, C. R., Merrill, F. E., Barlow, D., and Mariam, F. G.. Fri . "Nonuniform radiation damage in permanent magnet quadrupoles". United States. doi:10.1063/1.4892803.
@article{osti_22314418,
title = {Nonuniform radiation damage in permanent magnet quadrupoles},
author = {Danly, C. R. and Merrill, F. E. and Barlow, D. and Mariam, F. G.},
abstractNote = {We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.},
doi = {10.1063/1.4892803},
journal = {Review of Scientific Instruments},
number = 8,
volume = 85,
place = {United States},
year = {Fri Aug 15 00:00:00 EDT 2014},
month = {Fri Aug 15 00:00:00 EDT 2014}
}
  • Recently there has been some concern about possible radiation damage due to ionizing particles present in high energy storage rings such as multi-GeV electrons, fast neutrons, or hard photons. Partial demagnetization has been observed on undulators after mis-steering of the injected electron beam. Our interest was focused to possible radiation damage of a permanent magnet insertion device during routine operation of a storage ring. Therefore, we repeated the magnetic measurements on one of the three 4.0 m long x-ray wigglers used at place [number sign]2 in DORIS III. This device is in operation since 1991. The results were compared tomore » the data taken before installation. The total dose was determined from measurements with thermoluminescence dosimeters and the known number of stored ampere hours. The results which show no significant degradation of the magnetic performance are presented and discussed.« less
  • No abstract prepared.
  • Most of radiation damages in materials are structural changes (radiation-induced defects), but the origins of radiation-induced demagnetization of permanent magnets can be explained by a magnetization reversal caused by a thermal process. We propose a model for the mechanism of radiation-induced demagnetization and suggest some protections strategies.
  • The Beamline 9 Wiggler was designed by Intermagnetics to produce a 16 milliradian fan of high energy x-rays into three experimental stations. The device has a 26 cm period and contains 7.5 full-strength periods. The minimum air gap is 2.1 cm. At minimum gap, a peak field of 1.9 Tesla and a half-period integrated field strength of {ge}16.646 T-cm were specified by the Stanford Synchrotron Radiation Laboratory (SSRL). A combination of analytical, PANDIRA, and scale models were used to develop a novel {open_quote}{open_quote}compact pole{close_quote}{close_quote} magnetic design. This design achieved 2.04 T peak field while maintaining a minimum of 17.816 T-cmmore » half-period integrated field strength. Magnetic performance of the device was confirmed through the use of an Intermagnetics-designed Hall Probe scanning system as well as by long and short coil measurements. {copyright} {ital 1996 American Institute of Physics.}« less
  • A radioactive radiation source in which the carrier absorbing the radioactive material or the material itself forms a permanent magnet or permanent magnet system is described. In this way the radiation source could be fasiened temporarily in the desired place on ferromagnetic parts, stands, or plates without using any mechanical clamp devices. Also, not too heavy ferromagnetic objects, which are to be irradiated or investigated, could be brought to adhere to the source itself. According to the claims the radioactive material could be embedded in the permanent magnet during its fabrication. It is also possible to construct the magnet frommore » activated materials. The preparation of the radiation source is described in detail. (J.S.R.)« less