[Isotope-prod] Target update

[Kevin Jordan]

Dear All,
My wife has developed a cough & we are both scheduled for COVID rapid test Monday at 16:30, hence I was not able to be on site this weekend as I had planned. Todd gathered up the stuff I needed and delivered it to my lab at BNNT to do final assembly of the targets.

The key challenge was to take a small “BB” of 250mg gallium 71 and make a disc. The “cheap” gallium would not re-solidify even at -5˚C! I used this to develop the techniques for assembling the targets and to understand physical properties of gallium. I had concerns that the Ga71 may not melt at reasonable temperatures or refreeze. Fortunately it behaved well, as photos below show. A plug was added to the solid graphite block to assure proper contact with rear spring loaded lever lock.

There is a solid graphite block installed in the raft now, this will act as the pulsed beam dump. The block labeled G2 is slated to be installed Tuesday AM and exposed at 100 watts for 1 hour. Once this is complete there is a 1 hour Radcon cool down then the block labeled G1 will be installed, this is the solid block with rear spacer to ensure proper contact to the rear spring loaded lever lock. This one is to be exposed at 5kw of electron beam for ~20 minutes until temperatures stabilize then beam will be shut off. This will be retrieved Wednesday morning and replaced with the graphite block filled with ~60 grams of gallium. The temperature data as well as before & after photos confirming survival of the graphite block will be sent to the ERR team for authorization to proceed with the production exposure. This irradiation will be for 34 hours at 5 kWatt. The run will end no later than noon on Friday January 15, 2021. We hope that all goes well,  the run could complete as soon as Thursday PM.

Thanks for all the support!
Kevin

[cid:DE3A577A-6BA8-4925-9D73-5629BD127E22]
250 milligram Gallium 71 on hot plate at 50˚C - molten.

[cid:E9EC94D9-B918-492A-A14E-D7869D827296]
Cover placed to “flatten” Gallium 71.

[cid:21D45B95-EBA8-4A73-AF96-5D5BFE22669A]
Resulting disk after placed in freezer ~9mm x 7mm x 1mm - note that the cheap gallium did not re-solidify when placed in -5˚C.

[cid:78F754FB-8C96-477B-8344-89A0A5E9FB05]
I machined 3/8” x 1mm indent to hold Gallium in the end of the graphite block.

[cid:64F4B98B-AD94-4344-A15D-82D27509FA40]
Gallium 71 disc positioned in the graphite block.

[cid:4D9AF3E9-F641-45D9-BA7A-FF582EE3ADE9]
Completed stack of Gallium 71 (250mg), 100µ Vanadium (49.2mg), 10µ Nickel (9.1mg), each separated by 100µ graphite foil and wrapped with two layers of ~60µ Kapton tape.

[cid:F59CC477-E091-410F-A635-13EBE217A8A0]
Three required blocks + spare.



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