Historical Content Note: The following material is reprinted from publications from throughout Fermilab's history. It should be read in its original historical context.

First 200 BeV Tracks in 30-inch Bubble Chamber!

The fifth anniversary of the National Accelerator Laboratory on June 15, 1972, was highlighted by the display of the first photos of 200 BeV tracks in the 30-inch Bubble Chamber. Announcement of the successful run of the beam, which occurred about 5:45 a.m. on June 15, was made by NAL Director Robert R. Wilson at a meeting for the 950 employees of the Laboratory. "It means that we're in business," he told the group. "The whole Laboratory is now being exercised."

Ernest Malamud. head of NAL's Internal Target Section, announced that one million elastic scattering events had already been observed at the internal target positioned in the Main Ring vacuum chamber at Building C-0 as part of Experiment No. 36. "We are doing very significant experimenting now," Dr. Wilson commented. "This is becoming a physics laboratory and we can talk about the discoveries that will be made here."

Dr. Wilson also outlined the immediate goals in the continuing NAL development program, such as increasing beam intensity by a factor of 1,000 and bringing all experimental areas into operation. "Our success from here on will be measured by our efforts in these directions," he said.

The Bubble Chamber success came after a week of sustained efforts that began June 8, 1972 when the first 200 BeV beam was handed off to the Neutrino Laboratory from the Switchyard. (On May 29, 72 BeV particles went through the Neutrino Line in an initial test.)

With the main accelerator operation consistently reliable at 200 BeV, the tuning of the Neutrino line at the higher energy became the highest priority assignment at NAL. For the Neutrino Laboratory staff, day and night hours became one thing. Deeply engrossed in the intense efforts, many found it difficult to break off even for sleep; twenty-two hour shifts were not uncommon among the physicists. One reported finding a fellow physicist parked along Butterfield Road after one of these long stints, who commented simply, "My car ran out of gas and so did I."

The NAL Neutrino Line is 1.5 miles long. Adjustments will be necessary, at all of the ten buildings on the Line. Systematic, patient analysis of progress and problems was the key to success. The sport of the job was reflected in the simple jubilation of the entry in the log book at 0545 on June 15, 1972: "Got him!"

By Monday, June 19, after a period of several days of "cleaning up" the tracks, staff members were able to record in the log: "Looks Good," as they accumulated the first complete roll of film of photographs of the 200 BeV beam passing through the liquid hydrogen in the Bubble Chamber.

As described in the December 2, 1971 issue of The Village Crier, the Chamber was moved to NAL from Argonne during 1971. Studies of the interactions of particles that were recorded on the first test pictures began. Researchers from approximately thirty laboratories were involved in the ten approved experiments which were planned for this area. The first of these, Experiment Number 141, got underway with pictures of 200 BeV proton - proton collisions being measured on a round-the-clock basis at the Argonne National Laboratory as the experiment at NAL.

According to Louis Voyvodic, physicist in charge of the 30" Chamber and a participant in the first experiment, "The tracks and interactions seen in the chamber on the morning of June 15 were a beautiful sight, both scientifically exciting and aesthetically striking."

He added, "It was also satisfying to watch the enthusiasm and feeling of fulfillment, after years of effort, as physicists, engineers and technicians from the accelerator, from the beam lines and from the Bubble Chamber areas took turns viewing the tracks flashing away in the Chamber."

One of the first photographs taken with the 30-inch Bubble Chamber at NAL June 15, 1972. A 200 BeV proton enters the Chamber and interacts with the liquid hydrogen; resulting collision produces a spectacular event with ten visible nuclear fragments emerging; tracks were nearly 30 inches long (1 of 2)
NAL employees gathered outside the Curia on Thursday, June 15, 1972 for Directors meetingr (2 of 2)