Journal Article

PUBDB-2016-02977

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Measurement and tricubic interpolation of the magnetic field for the OLYMPUS experiment

Bernauer, J.Extern* ; Diefenbach, J.Extern* ; Elbakian, G. ; Gavrilov, G.Extern* ; Goerrissen, N.Extern* ; Hasell, D.Extern* ; Henderson, B. (Corresponding author)Extern* ; Holler, Y.DESY* ; Karyan, G.DESY* ; Ludwig, J.DESY* ; Marukyan, H.DESY* ; Naryshkin, Y. ; O'Connor, C.Extern* ; Russell, R.Extern* ; Schmidt, A.Extern* ; Schneekloth, U.DESY* ; Suvorov, K.Extern* ; Veretennikov, D.DESY*

2016
North-Holland Publ. Co. Amsterdam

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Please use a persistent id in citations: doi:10.1016/j.nima.2016.03.115

Abstract: The OLYMPUS experiment used a 0.3T toroidal magnetic spectrometer to measure the momenta of outgoing charged particles. In order to accurately determine particle trajectories, knowledge of the magnetic field was needed throughout the spectrometer volume. For that purpose, the magnetic field was measured at over 36,000 positions using a three-dimensional Hall probe actuated by a system oftranslation tables. We used these field data to fit a numerical magnetic field model, which could be employed to calculate the magnetic field at any point in the spectrometer volume. Calculations with this model were computationally intensive; for analysis applications where speed was crucial, we pre-computed the magnetic field and its derivatives on an evenly spaced grid so that the field could be interpolated between grid points. We developed a spline-based interpolation scheme suitable for SIMD implementations, with a memory layout chosen to minimize space and optimize the cache behavior to quickly calculate field values.This scheme requires only one-eighth of the memory needed to storenecessary coefficients compared with a previous scheme (Lekien and Marsden, 2005 [1]). This method was accurate for the vast majority of the spectrometer volume, though special fits and representations were needed to improve the accuracy close to the magnet coils and along the toroidal axis.

Note: (c) Elsevier B.V. The arxiv v1 version matches with the post referee version.

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Contributing Institute(s):

1. OLYMPUS Kollaboration (OLYMP)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF3-611) (POF3-611)

Experiment(s):

1. DORIS: OLYMPUS

Appears in the scientific report 2016

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Database coverage:
; ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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