SEQUOIA Overview

1

• SEQUOIA Overview
• Garrett Granroth (Instrument Scientist)
• David Vandergriff (Lead Engineer)
• ARCS/SEQUOIA IDT meeting
• March 20, 2005

2
Outline

• Overview
• Progress
• Procurement Status
• Installation Status
• Specific items
• T0 chopper
• Sample Area
• Magnetic shielding issues
• Summary

3
SEQUOIA Overview
Beam Stop
Core Vessel insert
Shutter insert
Front End shielding
Beamline shielding
Get Lost Tube
Detectors
Fermi Chopper
Detector Vessel
To Chopper
Guide
Poured In-Place Shielding
Sample Vessel
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Instrument Parameters

• minimum Dw/Ei lt 1.2
• Ei 10 2000 meV
• Lengths
• Moderator to Fermi chopper 18.0 m
• Fermi Chopper to sample 2 m
• Sample to Detector 5.5 m
• 43m2 of detectors covering 1.2 Sr
• Span -30o -3o, 3o 60o horizontal, -30o
  -3o, 3o 30o vertical.
• 138,000 pixels

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Instrument Performance
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Location
SEQUOIA
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SEQUOIA and ARCS
Beam Stop
Detector Array
Get-Lost Tube
Sample Vessel
Detector Vessel
5.5 m
Fermi Choppers
2 m
ARCS Beamstop
T0 Chopper
8 m
Shutter Insert
10 m
CVI
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System Overview

• Beamline 17/18 Pit Area

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SEQUOIA Dates

• Conceptual Design Review March 04
• Shutter Insert Guide on Order with CILAS April
  04
• Critical Decision - 1 (Alternative Selection and
  Cost Range) approved by DOE (CD-1) April 04
• Preliminary Design Review May 04
• Core Vessel Insert Installed July 04
• Guide Design Review August 04
• Post Doc Matthew Stone arrives at HFIR August
  04
• IDT meeting October 04
• CD-2A and CD-3A (long lead procurements) approved
  October 04
• Shutter Inset Guide Installed December 04
• Engineer Mark Overbay joins the SEQUOIA team to
  work on Choppers January 05
• Detector Vessel and Sample Vessel Design Review
  February 05
• Shutter installed February 05
• IPR and CD-3 Review (all procurements) March 05
• Guide vendor selected March 05
• Joint ARCS /SEQUOIA IDT meeting March 05
• Early procurement permitted because these
  items are time critical

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Instrument Procurement Progress
Legend Awarded Vendor chosen Out for bid In next
6 months BOA component
Beam Stop
Front End shielding
Beamline shielding
Get Lost Tube
Detectors
Fermi Chopper
Detector Vessel
To Chopper
Guide
Poured in Place shielding
Sample Vessel
11
In-Monolith Component Installation

• Shutter Insert(Feb 2005)
• Core Vessel Insert (Aug 2004)
• Shutter Insert guide (Nov 2004)

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Core Vessel Insert Installed
Aug. 2004
Apr. 2004
Beamline 17
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Shutter Guide and Insert Installation
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T0 Chopper

• Vertical axis narrow band width design.
• Background reduction
• Max Ei 2 eV
• Up to 180 Hz operation.
• Constant 31 cm Inconel X-750 to block beam.
• Ultimate 160 ksi.
• Yield 100 ksi.
• Eliminates need for bandwidth chopper.
• Working closely with ARCS team
• Simplifies shielding design
• Approximate spin up times
• 5 min per increment of 30 Hz
• Magnetic Bearings reduce maintenance frequency
• Initial rotor analysis completed
• Specification under preparation.

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Crystal alignment with T0 chopper

• 4 steps in phase to match white beam
• operate at 31Hz to sweep profile 1/s

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Sample Area Design

• Vacuum Isolation during sample change out
• Standard Flange with Rotary options
• 1 Ton max weight for sample environment
  equipment
• Non magnetic material
• Ease of access for
• Sample Change
• Fermi Chopper Change
• Cryogen Fills
• Shielding for
• Personnel protection
• Background reduction
• Reduction of stray magnetic fields

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Sample area
Top access port
Sliding top cover
Quench vent
Magnetic shielding
Jib crane
Equipment shelf
Enclosure door
Sample Stick (oxford Magnet sized)
Sample equipment
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Sample Area looking up
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Sample Area

• Enclosure dimensions
• 108 w x 120 d
• 96 inside height
• 72 x 108 shelf
• Jib crane to lift sample environment equipment,
  Fermi choppers.
• Sliding door for access.
• Sliding top access port for top loading and
  long sample sticks.
• Mezzanine access on the ARCS side.
• Equipment lift to raise and lower sample
  environment equipment.
• Considerable coordination with the ARCS team!

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Magnetic field Policy

• General principal
• Dont generate stray fields that mess with other
  beamlines
• Multiple Approaches
• Meet low limit (50 mGauss proposed limit)
• Negotiate with affected neighbors for a different
  limit
• Spin Echo is affected neighbor. They have
  calculations to show they need 50 mGauss.
• We have calculations that show we cant meet 50
  mGauss with a15 T unshielded magnet.
• Management decides on an experiment by experiment
  basis if you can temporarily violate above points
• Self shielding compensated magnets are under
  development

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Magnetic shielding - top
Incident beam
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Magnetic shielding Front
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Cut from closest interference

• Plate on ARCS side makes matters worse
• Rounded edges dont help in far field
• 5cm is 200 layers of electric steel
• Need IDTs opinion on the need for fields

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Summary

• Progressing on SEQUOIA
• Guide vendor selected
• Detector Vessel and Sample Vessel out for bid
• Shielding, Fermi chopper, and T0 chopper to go
  out for bid in the next 6 months
• In monolith components installed
• A workable sample area has been proposed
• T0 chopper allows crystal alignment
• Magnetic shielding We need your input