Deuterated Target Preparation

Author: Tim

Several of the cyclotron experiments have been based on its ability to generate neutrons from the D-D reaction. This paper has more details about cyclotron’s neutron production, however this page outlines the details in making the deuterated targets.

Three samples of titanium, a 1/8-inch thick piece, 0.010 thick, and portion of a 3/8 Ti bolt.

Samples line up inside a quartz tube placed within a clam-shell tube furnace.

The quartz tube is part of an UHV vacuum system that gets into the 10E-6Torr range.

The tube furnace can then heat the samples as high as 1000 celsius. Under high vacuum, adsorbed gases are driven out over 5 hours of heating at about 900 degrees C.

Then the fun part: While hot and under vacuum, introduce the deuterium gas up to a little more than one atmosphere (to ensure positive pressure and now backfill of air). I use a bubble at the end of a check valve to ensure continuous flow ~1 bubble per second or so.

Once at an atmosphere, shut off the tube furnace, open it, drop it down and back it away.

Let the samples cool while in the pure deuterium environment.

This cooling takes about five to ten minutes.

Once at an atmosphere, shut off the tube furnace, open it, drop it down and back it away.

Once at an atmosphere, shut off the tube furnace, open it, drop it down and back it away.

At first there is not much of a difference in appearance.

At a few hundred degrees C, sounds can be heard coming from the samples. The can best be described as “tink tink tinking” as they cool.

Then pretty drastic physical changes occur near the final stages. Swelling, splintering, cracking, crinkling and buckling.

The samples grow about 10% in each direction, and all gain considerable mass too, indicating about 200 atomic percent or more capture – that is for every titanium atom, there are two or more deuterium atoms captured.

Top view of the mounting of the thin target on the end of the 12-Inch Cyclotron’s radial probe.

Side view of the mounting of the thin target on the end of the 12-Inch Cyclotron’s radial probe. The titanium sheets distortion is obvious here.