The Photo-detachment region is where our ion beam is crossed with a laser beam.
We use a 1.4 kW diode laser, at 975 nm. The laser crosses the ion beam inside a floating cell.
The floating cell is a rectangular tube that is electrically isolated from the rest of the apparatus.
We can put an arbitrary potential on the cell, this will control our center of mass ion-neutral collision
energy.

When the Ion beam leaves the source it has the intial kinetic energy given by the source.

1. E_Ion = E_Source

When the Ion beam enters the floating cell, the potential of floating cell will alter the Ion energy.

2. E_Ion = E_Source + E_{Float Cell}

Neutrals made by the laser inside of the floating cell will be locked in at this energy.

3. E_Neut = E_Source + E_{Float Cell}

When the Ions leave the floating cell they will return to the original energy, and we can control the collision energy between Ions and Neutrals this way.

4. E_Ion = E_Source