Solid Magnet

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magnet candidate



talk and note

there are more talks at collaboration meeting page

study from 2016

Jay Benesch's note

study by 2012

  • Zhiwen's update on base on Eugen's study. it leads to CLEOv8 pptx pdf

SoLID magnet design

Comparing Magnet

Integral to the SoLID spectrometer design is a large solenoid. Several existing solenoids are under consideration by the collaboration. These include the magnets from Babar, Cleo, CDF and ZEUS

Babar CLEO CDF ZEUS Custom
Cryostat Inner Radius 150 cm 150 cm 150 cm 86 cm 100 cm
Length 345 cm 350 cm 500 cm 245 cm 230 cm
Central Field 1.49 T 1.5 T 1.47 T 1.8 T 2.68 T
Compact Flux Return Yes Yes No No Custom
Current density variation (current/length) Up and Downstream ends (25%) of coil have 2x current of central 50% Up and Downstream ends (25%) of coil have 1.04x current of central 50% No 25% more current at ends 50% more current at ends
Magnet Map Update Date 2011/4/6 2012/7/27 2011/4/6 2011/2/4 2011/6/21
Poisson input deck CLEOv8.fce
Poisson SF7 output BABARv4.sf7 CLEOv8.sf7 CDFv4.sf7 ZEUSv1.sf7 SolCustv1.sf7
grid info grid size: 1cm, Rmin 0 Zmin -400, Rmax 400 Zmax 600, R and Z increments: 400 1000 grid size: 1cm, Rmin 0 Zmin -600, Rmax 500 Zmax 600, R and Z increments: 500 1200 grid size: 1cm, Rmin 0 Zmin -400, Rmax 400 Zmax 600, R and Z increments: 400 1000 grid size: 1cm, Rmin 0 Zmin -300, Rmax 300 Zmax 475, R and Z increments: 300 775 grid size: 1cm, Rmin 0 Zmin -400, Rmax 400 Zmax 600, R and Z increments: 400 1000
PDVIS target "designed" Location z=+10 z=+10 z=+50 z=0 z=0
plot by Possion
plot by SF7toGEMCmap.C
BABARv4 SF7map.png
CLEOv5 SF7map.png
CDFv4 SF7map.png
ZEUSv1 SF7map.png
SolCustv1 SF7map.png
Notes: (1) the center of the magnet is taken as the orgin. The target offset for the CDF magnet makes up for the fact that the magnet is longer than the Babar magnet. (2) The upstream pole pieces of the CDF and ZEUS magnets can be angles for SIDIS acceptance needs
Excel File to help make poisson input magnets.xlsx older magnets.xlsx older version

version history

CLEOv8 update with realistic CLEO-II design and same magnet for both PVDIS and SIDIS

CLEOv6_PVDIS and CLEOv6_SIDIS update with CLEO separated yoke

CLEOv5 The CLEO yoke has been updated with more shielding at front end cup for fringe field and tweak end cup with a triangle piece to minimize fields in end cup.

BABARv4 has SIDIS endcap, PVDIS can fit but not optimized because the endcap nose doesn't extend long enough to the coil region.

Field Integrals for Baffles


Fields at fixed radius

Solidfieldint.png Solidfieldintratio.png

Field integrals and ratios for the various magnets are shown above. The integrals assume a trajectory of 28° beginning at the center of the target. The efficiencies for the baffle designs scale with the field integral shown here.

Poisson Superfish Howto

How to produce the filed map

use program "Poisson Superfish" from LANL (home page), get it from  direct link or local copy      
  • It's a windows program and need installation, it can run with wine in linux or winXP/win7
  • see including manuals and examples for detailed help.
  • We have been using v7.18, the latest v7.19 came out in 2013, but the change doesn't affect the program we are using, refer to changelog
Here is a quick summary of howto.
  • input file ".am" is a text file with regions defined by ploycons.
  • produce mesh by AUTOMESH.EXE with input from a ".am" file, output file will be ".T35" with only geometry and material
  • use WSFPLOT.EXE to view the ".T35" file to verify the setup.
  • then run POISSON.EXE with the ".T35" file which will be added with field.
  • use WSFPLOT.EXE to view the ".T35" file with field
  • then run SF7.EXE on the ".T35" file, do the field extrapolation for grid with desired ranges and steps, the result is in a txt file "OUTSF7.TXT" which includes a 2D field map.
  • run SF7.EXE on the ".T35" file, do the field extrapolation for a line, arc or curve, besides "OUTSF7.TXT", a ".TBL" file is produced and can be directly viewed by TABLPLOT.EXE
  • run FORCE.exe with input ".fce" which gives points in a region, the resulting "OUTFOR.TXT" gives the force on the region.

Field map input files

all files are at svn "database_io/solid/field/"

  • "" BaBar_magnet from_Eugene with center of solenoid at 600cm
  • "" BaBar magnet files created by Zhiwen, based on Eugene's file but moved to the center of solenoid to origin
  • "BABARv*.am" BaBar magnet
  • "CLEOv*.am" CLEO magnet
  • "CDFv*.am" CDF magnet
  • "ZEUSv*.am" ZEUS magnet

Field map output files

located at Solid website

  • sf7 files are direct output from poissonsuperfish program
  • dat files are conversion from sf7 to GEMC format

refer to Magnetic_Field_Map

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