David Gelphman's Blog


Moving the Crystal Ball

I never expected that my graduate school experience would include a ride in a C-5A military transport airplane, much less the opportunity to be in its cockpit during a mid-air refueling. But amazingly it did.

In April of 1982 I was part of a team that moved the Crystal Ball, a detector used for particle physics experiments, from Stanford Linear Accelerator Center (SLAC) in Menlo Park, California to Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany. The Crystal Ball was unique among detectors used in particle physics in that it consisted almost completely of a spherical array of sodium iodide crystals and was an excellent tool for measuring the energy of gamma ray photons that can be produced in collisions of high energy particles. The success of the Crystal Ball at SPEAR resulted in an invitation from DESY to move it to the newly upgraded DORIS storage ring in Hamburg. (Some additional detail about the detector itself can be found in my PhD dissertation, starting on page 23 of the linked PDF file.)

Because the Crystal Ball was largely made up of sodium iodide, it needed to continually exist in a temperature and humidity controlled environment. Without this special handling, the crystals themselves would corrode and be worthless for experimental purposes. In addition there were concerns about it encountering excessive g-forces (i.e. sharp jolts) that might crack one or more crystals. Ultimately it was decided that instead of sending the most delicate portion via cargo ship, it would be transported by a C-5A military transport plane.

C5A overview

The heart of the detector was carefully packaged into special boxes constructed with a styrofoam cushion against shock and which allowed the flow of dry nitrogen to control the humidity. These boxes were loaded into a specially outfitted US shipping trailer and trucked to Travis Air Force Base northeast of San Francisco. The trailer itself was loaded into the C-5A and detached from the truck which stayed behind.

The cargo area of a C-5A is massive tube. Here’s a photo prior to the trailer being loaded.

Down the Plane Barrel

Prior to the flight we got a tour of the cockpit and I got to take some photos. This was as close as I ever expected to get.

Cockpit before flying

There were a couple of unusual aspects to flying in the passenger portion of the C-5A. For improved safety, the seat backs are in the direction of travel. At first this seemed odd but once you could no longer see out it really didn’t make any difference. And the windows themselves were either non-existent or were so high up that you couldn’t see out of them while seated. The biggest issue while flying was that it was LOUD. We all were given earplugs to wear during the flight but even with them it was loud. No doubt it was the most claustrophobic and uncomfortable flight I’ve every taken. But also the most incredible.

We took off and after a few hours there was going to be a mid-air refueling. I don’t know if that was strictly necessary or was done so that they could practice the process. Either way it was incredibly exciting because our team from SLAC was invited to the cockpit in groups so we could watch!

When I got to the cockpit, this was the scene I saw.

Cockpit During Refueling

After a short while I got to locate myself just behind the pilot’s seat, to the left of his left shoulder. And what I saw startled me at first. Flying at our speed, just above and in front of us, was another airplane. The photo below was taken through the left side of the windshield in the cockpit and you can clearly see the boom that was already attached to our plane, providing fuel. I don’t know the distance between the two planes but it could have been as close as 20 feet and almost certainly wasn’t more than 50. Let’s just say it was close.

Midair Refueling A

Below the boom is a window where the boom operator in the other plane can see our plane and properly guide the boom. I was able to take a photo where you can see the boom operator’s face through that window.

The Fueling Operator

Once the refueling was complete, the boom was withdrawn and the other plane slowly flew away from us.

Midair Refueling C

Once it got a sufficient distance away, the fins on the boom became visible.

Midair Refueling E

Midair Refueling G

What an amazing opportunity! It was an unforgettable experience to be in that cockpit. And I can’t believe that I got to take photos.

Once we’d taken off, the landing was the next risk point in the journey. Because large g-forces could be damaging to our cargo, we’d equipped the trailer with recording accelerometers so we could monitor the conditions. I’m not exaggerating when I say that it was the smoothest landing I’ve ever experienced while flying. We landed safely and encountered no problems with the detector.

Here’s a photo of the trailer being safely unloaded from the C-5A. That’s me with the red backpack on the right side of the photo.

Arriving in Frankfurt

They took a group photo of the flight crew plus our team. The civilian team was led by Dr. Ian Kirkbride from Stanford and Dr. Don Coyne from Princeton. Chad Edwards (now at JPL) was a Cal Tech graduate student at the time and is the redhead at the bottom-left in front. I’m at the back with my hair flying, sandwiched between two air force men. Other members of our team were Jim Nolan, John Hawley, Bob Parks, and Sal Fazzino. (Apologies to anyone I left out or whose name I got wrong. It was almost 32 years ago!)

Flight Crew

Now all we had to do was drive from where we’d landed at Rhein-Main Air Force Base in Frankfurt to our final destination in Hamburg. But there was a surprise in store for us.

During the drive from Frankfurt to Hamburg we took turns traveling inside the trailer, riding with the crates holding the Crystal Ball hemispheres. The idea was to ensure that the environment was being maintained during the trip. At some point along the drive I was in the windowless trailer when the truck unexpectedly slowed down and stopped. The truck had blown out a gasket or thrown a rod and that was going to require a major overhaul. That didn’t seem like too big a deal until we found out that there was only one other truck in Germany that could pull our trailer. Apparently the coupling needed for pulling an American trailer was rarely available. It’s safe to say that there was a lot of confusion when the breakdown occurred. I think this photo captures that.

Frankfurt to Hamburg

In truth, the remainder of the trip went smoothly. The replacement truck arrived the following day and we were able to transport the trailer containing the Crystal Ball safely to its new home at DESY. Here’s a photo of the trailer after the Crystal Ball was unloaded from it at DESY.

Crystal Ball Trailer

And the Crystal Ball was installed inside the radiation area where the beams collide.

Experiment Pit

It was all quite an adventure. And one of my fondest memories from graduate school.