life at the cyclotron

[nibot]

In this experiment we place copper foil in the beamline and intend to measure the rate at which alpha particles transmutate the copper into a certain isotope of gallium.

In the control room, Ray Thatcher tunes the beam. This is 'mission control' for the cyclotron, with all the settings controlled by switches, buttons, and knobs. One wall sprouts BNC connectors, a patchboard for signals from the cyclotron.

The beam emerges from the cyclotron and is diverted via magnets into one of several "caves," radiation-shielded rooms where the experiments are located. This is the end of the beam in Cave 3. The caves are surrounded by concrete blocks. There's an escape hatch on the floor in case, for some unprecidented reason, you get stuck inside. Moreover, there are "guillotines," explosive doors that seal off an area to prevent the spread of radioactive materials in an emergency.

The beam is tuned, but just to be sure, we stick a piece of graph paper on the beamline target. Ray's tuned the beam to a nice colimnated stream of 8 MeV alpha particles — the cross section of the beam is burned into the paper.

Unfortunately the copper foil ruptured during the run. We think it was because of gas pockets between the copper foils which expanded while we pumped the beamline down to vacuum.

To avoid spreading fragments of various radioactive materials, we work in a fume hood, wear a lab coat. Rick places the samples into containers.

Our samples.

Michelle prepares new sample holders, with a larger air gap to vent during vacuum pumping.

The samples were ruptured but we try to take data anyway. The samples placed in a gamma-ray spectrometer and data is recorded.

I leave at midnight. Michelle says for the next two runs — the final one was successful — and leaves after four.