IB coil filling material

[Batonas]

Hy. I am building a DD coil for IB detector. The question is about the filling material. Usually in DIY projects epoxy is used, but it it both heavy and expensive. In ITMD it is suggested to use plastic paste dissolved in solvent or foam. Is there enough structural strength with these methods? (had instability issues due to movement before when making previous coil). What are your preferences and materials are used in commercial coil designs?

[waltr]

I mix a lot of micro-ballons into the epoxy to reduce weight.

[ionut_mtb]

Like Waltr said micro balloons mixed with epoxy and some xps foam pieces glued (because will float into the epoxy mix otherwise) on the coil housing where is to much space left.

[waltr]

A hint on filling DD coil shells:
The coil NULL is very, very sensitive and the epoxy curing can move the coils resulting in the null going out.

Put some dams where the coils overlap and not fill completely with epoxy on first pour.
After epoxy cures did check/adjust null then put a few drops of epoxy to hold coils in place.
Check adjust before finial encasing with epoxy.

[Batonas]

Thank you for the suggestions. Is it good idea to use fiberglass reinforcement? (loose cuttings and strands)

[waltr]

Thank you for the suggestions. Is it good idea to use fiberglass reinforcement? (loose cuttings and strands)

Not really. That adds strength but probably not needed.

[Gwil]

Has anyone tried using expanded polystyrene beads mixed into epoxy? No doubt not as strong a result as with glass microballoons but I don't know how important this is.

[MartinB]

I think polystyrene beads will be too big. They are also quite soft. I doubt that you will get sufficient epoxy penetration around your coil and it will be weak. Stick with glass microballoons.

[getsa]

Fill with mounting foam and then cut out the unnecessary with a paper cutter. After that chamfer some milimеters depth in the hardened foam with sandpaper for the final epoxy layer.