sbs magnet

John J. LeRoseHall A Collaboration Meeting, June 2010

SBS Magnet

SBS: a “large” acceptance, small angle, moderate resolution device

48D48 Basic Geometry

Have had contact with the contact engineer at

BNL. The magnet isn’t going anywhere.

Present Status of the Magnet(s)and Power Supplies

• Have made contact with the engineer at BNL who will be our contact for the property transfer.

• The magnets are “not going anywhere”.• Power supplies are also available, but old:

– Refurbished in the 80’s– Customized controls

• Anticipating having funding to move the magnets in October at the earliest, have tentatively planned a trip to Brookhaven in August to check things out in person and start arrangements for the transfer.

Needed Modifications to the Magnet

• For small angles at short distance– Cut opening in Yoke– Modify coils

• For Polarized Target & background control– Add field clamp to reduce field at target

• For beam transport to the dump– Field clamp (again)– Add magnetically shielded beam pipe– Add solenoid

Shielded Beam pipe

Field Clamp

Layout of system with part of yoke removed

Modified Coils

B at target < 2 Gauss

With magnetically shielded pipe with 1kA/cm current density solenoid

Calculations by Stepan MikhailovUsing “Mermaid” (units are kG, cm)

Nice clean magnetic field

5105.369.360013.0

69.3611

B

Bdl

mTBcGeVP

mTdlBy3

' 103.1

yy’

x

x’

θ

1 mm @ 30mEffect on beamline by transverse field is effectively eliminated

Various Views of the Modified Magnet

TOSCA modeling update

• Spring 2010: Robin Wines was assigned the task of doing detailed TOSCA modeling of the SBS magnet and the proposed modifications

• She is still creating/correcting the TOSCA model• Expect 1st results next week!

Optics

It’s really very simple!

This is what it looks like to me!

SNAKE P = 7-9 GeV/c

δ (%) (Momentum) 0.48

θtar (mrad) 0.16

ytar (mm) 0.9

φtar (mrad) 0.30

Expected Performance

Conclusion

• Magnet and power supply exist and are available• Magnet will work nicely

– with proposed modifications– TOSCA modeling of modifications is ongoing

• Will start to actively try to acquire the magnet(s) and power supply(ies) when funding is clearer

• Optics are very simple