Hall C SHMS Fringe Field AnalysisMichael Moore

Hall C Winter Meeting 2-22-2014

Outline

• The Fringe Field Problem• TOSCA model• Results of simulations• Conclusions• Work that still needs to be done

SHMS Elements

Q3 Q2 Q1 HBTarget

Dipole

How Close is too Close?

HB Yoke

Cryostat(coils inside)

Beamline

HMS Q1

The Model

MSU’s 1006 Fe 1006 Fe 1010

HB Q1

Q2Q3

Displacements

Beam Dump Window4” diameter

x

𝑥=(𝑟 −𝐷𝑥)cos (𝛼)cos (𝛾−𝛼)

3𝑜

𝜃

𝛼

𝛾

z

x 𝐷𝑥𝑟

𝐷

Target (9.21,-175.76)

49 m, target to dump distance

*Not drawn to scale

∎3𝑜 𝑖𝑠𝐻𝐵𝑏𝑒𝑛𝑑𝑖𝑛𝑔𝑎𝑛𝑔𝑙𝑒

Beamline axis

Displacement from center of beamdump window

∎𝜃 𝑖𝑠𝑆𝐻𝑀𝑆𝑠𝑐𝑎𝑡𝑡𝑒𝑟𝑖𝑛𝑔𝑎𝑛𝑔𝑙𝑒∎𝛾=𝜃+3

Beam Trajectory

“As Built” Fringe Fields

HB Q1 Q2 Q3

Integral: -126664Maximum: 1825.34Minimum: -2796.38

By Along Beampipe “As Built”, 11 GeV

By (G

)

Z (cm)

Wedges Fringe Fields

By (G

)

Z (cm)

By Along Beampipe “Extra Fe”, 11 GeV

HB Q1 Q2 Q3

Integral: -72477.1Maximum: 1427.82Minimum: -1814.02

“As Built” and Wedges Displacements

60 cm Pipe

HB

Pipe

Two meter Pipe

HB

Pipe

Two meter Pipe with Q2 Collar

Conclusions

• Run pipe and Q2 collar at more angles and energies• Optimize for smallest pipe length• Add HMS (at least Q1) to the model

Still to do

• As built, the SHMS is a >10 degree spectrometer• With extra Iron on the yoke it is a > 9 degree spectrometer• Iron pipe with wedges shows promise as a solution

Fitting the Beam in the Beamdump Window