Target Lab

NOTICE

The Target Lab here at FoxLab has suffered significant atrophy since it was disassembled for asbestos removal. It has very limited capabilities at the moment. Planning is underway to restore it to its previous functionality. Information regarding current and future capabilities will be posted here as time permits.

General Information

Target Frames

Standard target frames used here at FoxLab. CAD files for most of these frames are available. Use the contact link below to request them.

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  Original "standard" FSU Target Frame

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  Large FSU Target Frame

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  SPS (old Yale) target frame w/ 0.375" aperture

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  SPS (old Yale) target frame w/ 0.500" aperture

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  Adapter for mounting small FSU frame on SPS(old Yale) target ladder

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  Tandem Terminal Stripper Foil Frame

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  External 2nd Stripper Foil Frame

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  CLARION chamber target frame

Current Capabilities

Pure Lithium Targets

One of the unique capabilities available here at FoxLab is the ability to produce pure pseudo-free-standing lithium targets. Lithium metal is evaporated onto a polyvinyl formal backing which burns away when placed in beam. These targets are transported under static vacuum from the evaporator to the experimental chamber.

Personnel requesting pure lithium targets should be aware of the following:

• Historically, these have only been manufactured on frames with a nominal 0.375" ( 10 mm ) aperture. Requests for larger apertures will require technique development and success is not assured.
• The chamber in which the experiment will be performed must be capable of accepting one of the two vacuum target barrels available, or a new barrel must be designed/manufactured. As of this writing (15 Sep 2023) the original Yale SPS Chamber, the TR1 Scattering Chamber, the CATRiNA chamber and the newly installed SPS "Wild CeBrAs" chamber qualify.
• It is not uncommon for the polyvinyl formal backings to break during evaporation. It is best to have multiple backings on the target ladder to increase the odds of getting a usable target.
• The polyvinyl formal backing can contribute carbon, hydrogen, and oxygen until it burns away.
• Isotopically enriched lithium is available.
• Typical lithium thickness ranges 50 to 250 ug/cm2.
• The lithium targets must be at the bottom of the target ladder.
• Multiple thicknesses are possible, but the thicker targets must be at the bottom of the target ladder.
• Production of pure lithium targets requires significant evaporator setup. For this reason, lithium targets are typically available for installation in the target chamber Tuesday - Friday, barring extraordinary circumstances.
• Post lithium target production requires significant evaporator clean up. Consequently, if the provided targets are destroyed due to vacuum accident or other misfortune, it can take a full day to recover and make another attempt.
• As long as high vacuum is maintained in the experimental chamber, experiments of over a week in duration are possible on a set of targets.

Carbon

Carbon foils are made by carbon arc evaporation. Foils of 10, 20, 30, 50, 100, 150, 200, and 250 ug/cm2 are currently available on the small, "standard" FSU target frames. 50 and 100 ug/cm2 foils are available on slides and can be mounted on any frame upon request. If your experiment will tolerate it, these can be folded over the frame to produce double thickness, achieving 200 ug/cm2 as well. Other thickness will be made in future.

Carbon stripper foils for the Tandem are also manufactured by carbon arc evaporation. These are foils of nominal 190 Angstroms thick and are coated with collodion to facilitate handling during installation. A carbon stripper foil frame has two apertures. The Tandem holds nominally 300 frames, thus providing 600 foil positions. Students are sometimes called upon to mount foils on the frames and/or install the frames in the Tandem.

Limited Low Melting Point Material Targets

Source materials with melting points below about 800 degrees C can be evaporated currently using resistive heating. Other materials with higher melting points can also be used if their vapor pressures at these temperatures are high enough. Targets made with these materials on carbon backings are relatively straightforward at the moment. Self-supporting targets made with these materials may be possible as well. Requests for these types of targets should be made early and discussed with the targetmaker before assuming they are available.

CD2 Targets

Deuterated Polyethylene targets have been made here, but the techniques used have not yet produced high quality targets. While the capability exists here, more development work is required before these can be considered routine.

Rolled Metal Targets

Very limited capabilities exist for rolled targets. Contact the targetmaker for details.

Oxygen on Ta Backing

Manufactured through electrolysis using high-purity water. Isotopically enriched water can be used.

Possible Future Capabilities

• PID controlled substrate heating
• Electron beam evaporation
• In situ reduction-distillation evaporation
• Improved Target Storage Facility
• Improved Rolling capabilities
• Improved CD2 Production

Contact

Powell Barber mailto:pbarber@fsu.edu