4th april 20061 mice – magnetic shield configuration h witte, j cobb oxford university university...

4th April 2006 1

MICEMICE – –

Magnetic Shield ConfigurationMagnetic Shield Configuration

H Witte, J Cobb

Oxford University

University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK

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MICE – Magnetic Shields

• Dimensions– 1st shield:

ID=500mm, OD=1500mm, t=100mm

– 2nd shield: 120 mm downstream from 1st shield, ID=600mm, OD=1800mm, t=20mm

– 3rd shield: 100mm downstream from 2nd shield, ID = 660mm, OD=1800mm, t=10mm

• Inner radius of shields– John Cobb’s estimate

End

Coi

l 2

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Magnetic Shields – Inner Radius

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Forces on Shields

Force [N] Force [N]10 mm shift

Force [N]20 mm shift

Force [N]rinner, 1st shield = 220 mm

1st shield 6e4 6.45e4 6.9e4 6.61e4

2nd shield 6.9e3 6.77e3 7.2e3 7e3

3rd shield -80 -220 -200 -94

The forces are not a concern

Note: Shifts refer to all coils being moved towards end coil no. 2

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Nomenclature

• Z: Symmetry axis of MICE

• R: direction orthogonal to Z (radius)

• dz: used in the plots for different points in z between two shields. Point of reference is always the shield closest to the middle of MICE (i.e. z=0). – Example: plot of field between 1st and 2nd shield

dz=20 means 20 mm downstream from 1st shield

• Units: SI (T, m, N), unless stated otherwise

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Fields between 1st and 2nd shield

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Fields between 1st and 2nd shield

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Fields between 2nd and 3rd shield

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Fields between 2nd and 3rd shield

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Fields after 3rd shield

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Fields after 3rd shield

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4th Shield?

• 100 mm downstream from 3rd shield

• ID=0.72, OD=1.8, t=0.01

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Field between 3rd and 4th Shield

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Field after 4th Shield

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Field after 4th Shield

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1st Shield with smaller inner radius

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1st Shield with smaller inner radius – Comparison

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(Some) Conclusions

• Good field region for TOF2 starts at r=38 cm (40 mm from shield 1)

• Field between 2nd and 3rd shield looks good

• Reducing the inner radius of 1st shield may help to increase good field region for TOF2 – Works if PMT’s really close to 1st shield

• Open questions:– Minimum inner radius 1st/2nd/3rd shield?