Fermilab History and Archives Project

Accelerator History - Beam Controls

NAL GROUP BUILDS SUCCESSFUL BEAM MONITOR SYSTEM

Eddie Fuentes, trainee, and Steve Bjerklie with the SWIC and scanner they helped to build to monitor the proton beam in the Neutrino and Meson Laboratories
Eddie Fuentes, trainee, and Steve Bjerklie with the SWIC
and scanner they helped to build to monitor the proton beam
in the Neutrino and Meson Laboratories


Photo by Tim Fielding, NAL

The proton beam, for all its intensity and power, has often proved elusive, evading the clutches of even the most sophisticated control systems at the precise moment when it is to be studied. Largely unnoticed, in a corner of the Laboratory, a small group of people worked feverishly designing and constructing systems that measured quantitatively the size, position, and intensity of the beam produced by the NAL accelerator as it entered the various experimental areas. Their work was rewarded with a demonstration of their "beam profile monitoring and display system" in conjunction with proportional wire chambers and wire ionization chambers.

The group was under the direction of Fred Hornstra, electronics engineer in Research Services who later moved to the controls group of the Accelerator Section. Hornstra came to NAL in 1970 to head this development, following service as chief of operations at the ZGS external proton beam line at Argonne National Laboratory and at Los Alamos. The systems were built under the supervision of Technical Specialist Merle Haldeman, together with Maurice Harland, trainee. Greg Chartrand, technician, and Eddie Fuentes, another trainee, assisted in construction of the electronics. Marilyn Paul, secretary for the group, also helped in the lab.

"I was particularly impressed with the progress of our trainees," notes Hornstra. "Our group seems to have enjoyed the challenge of our project." Harland and Fuentes were members of the 1970 TAT class at NAL that received technical training at Oak Ridge, Tennessee.

Basically, the system worked as follows: Every time a particle went through the chamber, a wire received a pulse of charge. A counter and amplifier existed for each wire. The charge was amplified and sent to the miniature counter to be registered. After many counts, the contents of the counters were interrogated and displayed in a systematic manner. The wire which had the most counts appeared as the peak of a display on a screen, indicating the most intense portion of the beam. At each accelerator cycle, a new profile was generated and an analysis of the beam properties was displayed enabling operators to diagnose and alter the beam as desired.

Going one step further, an electronics engineer in the group, Ron Martin, designed an electronics system to link the proportional chambers to the computer control system in the beam line, so that the readings from the system could be viewed on a screen in the main control room in the Cross Gallery. In order to keep demand on the central computer to a minimum, Martin conceived and constructed a control which allows the detection system to operate without a computer. This he called CAMSAC, "Camac Stand Alone Controller."

Ron Martin exercising CAMSAC, for read out
Ron Martin exercising CAMSAC, for read out

Photo by Tim Fielding, NAL

This technically creative group also produced a system to monitor and display extracted proton beams as they were directed into experimental areas, a beam so intense that individual particles could not be counted. A somewhat simpler system was used to monitor such intense beams. Called SWIC (for segmented wire ion chamber), it collected the charge created by incidental beams without any amplification. The charge from each wire was stored on a corresponding capacitor and periodically the contents of the capacitor were interrogated and displayed on a screen.

Working on SWIC were Fuentes and J. Bondurant, with electronics designed by M. Haldeman and constructed by technician Steve Bjerklie.

All in all, this small group of people accomplished a lot in the past year.

Source: The Village Crier Vol. 3 No. 49, December 16, 1971

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MEET THE NAL ACCELERATOR OPERATORS

Keith Meisner monitoring Booster parameters
Keith Meisner monitoring Booster parameters
PROGRESS ON ACCELERATOR STUDIES, JANUARY 24 - 28, 1972
Modifications were underway to achieve better acceleration based on operating experience. These included operating the quadrupoles and bends on the same power supply system to provide better regulation. Some beam tests were conducted. Beam studies resumed Thursday, January 27th.


"The backbone of our operation...they're the reason we've been able to get so much done... they've got to know everything...they're an aggressive and enthusiastic bunch.." and similar laudatory expressions were used by their leaders to describe the daily doings of the 17-man group of Accelerator Operators. Probably the highest compliment was the cry, "We need more just like them!"

An Accelerator Operator's main job is to tune and control the NAL accelerators from a centralized Main Control Room to ensure continuous and peak performance. He must have a detailed knowledge of the operation, maintenance and repair of the Cockcroft-Walton machine, the linear accelerator, the booster synchrotron, the beam transfer system, the main ring synchrotron and many other components - no small task!

Gerry Ortlieb at the Booster console

Gerry Ortlieb at the Booster console

It was almost impossible to find "experienced" operators for NAL's one-of-a-kind machine. The size of the mammoth machine was matched only by the enormous complexities that arose in its operation. And, as one senior physicist expressed it, "We're all still learning how to tame the beast!" So where does one get experience for such a job?

An Accelerator Operator is, typically, a person who with technical training or equivalent experience with a heavy emphasis upon electronics. But for every "typical" operator, there are several exceptions, both in training and education. Two of the early operators held B.S. degrees in physics; another attended Northern Illinois University. Jim Hogan, the operator's group leader, made every possible effort to adjust work schedules to accommodate the education plans of his crew.

A new operator learns by sitting at the control panel with an experienced operator; he observes, he asks questions, then tries by himself...pressing buttons and adjusting knobs at the console, watching for the results on the screens above. He must be able to interpret the data displayed on the console and to make continuous decisions for further adjustments. But when he doesn't obtain the results he's after, he would be expected to know alternative approaches. And, he should know where to go to correct a malfunction and, in many cases, how to fix it. He not only becomes sensitive to the operating idiosyncrasies of the machines, but becomes versatile in his ability to diagnose a problem and take appropriate action.

NAL Accelerator Operators

Jeff Gannon
Jeff Gannon

Greg Urban
Greg Urban

Harland Gerzevske
Harland Gerzevske

Terry Hendricks
Terry Hendricks

The personal qualities of the operators really determine their success. They need to demonstrate intellectual curiosity about everything technical in their path. An operator must have the interest, the confidence, and the drive to make electronic and mechanical systems work as they should. Also, they have a desire to make suggestions to improve the system and follow them through to completion. In short, "energetic dedication" describes the typical operator.

In 1972 three operators were needed on each of three shifts - one each on the Linac, the Booster, and the Main Ring consoles. When the system was completed and refined, one person would control the entire installation. To provide a change and to keep the men abreast of development work, they were rotated every five weeks through a "tech area" where they did bench work involving laboratory and systems equipment.

NAL leaders pointed out to prospective operators that a physics laboratory such as NAL is always pushing the limits of technical knowledge. Equipment is used at NAL was far ahead of what most industry usied and, as a result, the scope of the knowledge a person can learn in such an environment was almost unlimited. As a result, a well-motivated person working in the operator's group could be given a lot of responsibility and turned loose on a system that will give him a lot of challenge. If he responds to the challenge, he becomes a good operator.

Accelerator Operators in 1972 included: Barry Barnes, Michael Froehike, Jeff Gannon, Harland Gerzevske, Terry Hendricks, Robert Hively, David Kindelberger, Mark Koenig, Bill Lee, Ewald Macheel, Bob Mau, Keith Meisner, John Nelson, Gerry Ortlieb, Byron Rodewalt, Greg Urban, and Roy Wickenberg.

For the young student or ex-student with a bent for electronics and for being where the action is, the assignment as an NAL Accelerator Operator offered a 21st Century opportunity. Young female electronic wizards were also welcome for this challenging work.

(Photos in this article were taken by Tony Frelo and Tim Fielding, NAL Photographers.)

Source: The Village Crier Vol. 4 No. 5, February 3, 1972




NAL BEAM HEADED TOWARD EXPERIMENTAL AREAS

PROGRESS REPORT - APRIL 17 THROUGH APRIL 22, 1972
An 80 BeV beam was extracted from the Main Ring and was detected in the Neutrino Target Hall at 9:50 p.m. on Friday, April 21. The accelerator was set on a 200 BeV ramp on Saturday, April 22, and extraction studies continued.

With accelerated beam circulating in the NAL Main Ring, the spotlight turned to the Switchyard section. It was this group's equipment that reached out and grabed the proton beam as it flew around the Ring 50,000 times per second and sent it to the experimental targets where the protons interact with target material.

Following the achievement of 200 BeV acceleration in the Main Ring on March 1, 1972 efforts immediately turned to extracting the beam from the Main Ring and guiding it to the experimental areas. On March 6th, about 5% of the circulating beam was extracted. On March 10, a beam spot was located further down in the Transfer Hall; on April 14, a beam of 3 x 109 protons was detected in Enclosure B. Then, on April 16, beam was obtained still farther down the line in the Beam Dump opposite the Meson line switch at Enclosure C. Finally, on Friday, April 21, a beam of 1 x 1010 protons was detected in the New Hall of the Neutrino Laboratory, some 3,200 feet from the Transfer Hall. The next step was to direct beam to the 30" Bubble Chamber located beyond the end of the Neutrino Laboratory area, approximately two miles from the Transfer Hall.

The electrostatic septum which pulls the proton beam out of the Main Ring so that it can be directed to experimental areas
The electrostatic septum which pulls the proton
beam out of the Main Ring so that it can be directed
to experimental areas

When full machine intensity is reached, efficiency of extraction must be greater than 99% in order to avoid the radioactivity that would result from beam lost at the extraction point. Extraction begins in an electrostatic septum 100 feet upstream of a long straight section of the Main Ring that also contains the injection system for the 8 BeV beam from the Booster into the Main Ring. The 20 ft. septum consists mainly of tungsten wires spaced .040 inches apart, resembling a thousand piano strings. The septum device is the most delicate element of the extraction system. It must provide enough bending to allow the beam it grasps to clear the Main Ring components at the straight section; the septum's field cannot affect the Main Ring during acceleration, and it must be thin enough so that it does not intercept any significant fraction of the beam. The electrostatic septum deflects the beam horizontally outward from the Main Ring. After drifting about 100 feet, it enters a Lambertson septum magnet which bends the beam downward. A series of specially-designed magnets, designated as "C" and "H" magnets, then guide the beam to a pipe in the tunnel wall that leads to the Switchyard. Beam transport from then on is much the same as in the Main Ring - by means of a series of dipoles and quadrupoles that send the beam to the desired experimental area.

Schematic of NAL Beam Switchyard. Beam travels from left to right
Schematic of NAL Beam Switchyard. Beam travels from left to right

Photo by Tim Fielding, NAL

The NAL extraction system was originally designed for "slow" extraction. In order to simplify the adjustments needed to bring the beam through the system for the first time, it was decided to provide for "fast extraction" at the present time. Fast extraction was also useful for bubble chamber experiments such as those which will occur shortly in NAL's 30" bubble chamber. Slow extraction required additional work on the system and was needed for many experiments whose detectors would be swamped by high intensities under fast spill conditions.

During the spring, 1972 accelerator shut-down period, the Switchyard Section incorporated a number of changes necessary to initiate the fast extraction. One-meter dipoles originally bumped the beam slowly into the wires of the electrostatic septum. While this technique was fairly efficient for extraction (maybe 80%), it required that the bumped beam be very parallel to the carefully-aligned wires.

According to physicist Richard Mobley, "It was decided to install a 'super-pinger' to give the circulating bunch of protons a .8 inch displacement at the electrostatic septum in a single Main Ring turn. The coils of the pinger were timed to reach their peak just as the 1.5 microsecond Main Ring bunch passed through them."

Mobley also reported, "A further refinement was the installation of another dipole bump system, placed to control the angle of the bumped beam at the electrostatic septum. Scintillator flags, ferrite core intensity monitors, and segmented wire ion chambers were also installed for beam detection."

The present Switchyard Section evolved from the former Beam Transfer Section that was headed by Al Maschke. Ed Bleser headed Switchyard commissioning. Group organization was defined by the nature of the elements of the system. For example, Richard Andrews, Dick Krull and Butch Bianci were associated with the electrostatic septum; Claus Rode and Bob McCracken worked on the magnetic channel. Aage Visser was responsible for power supplies. Rode also developed controls with Ken Sowinski, Jack McCarthy and Leon Bartelson. McCarthy and Bob Oberholtzer produced the pinger.

The design and installation of the Transport system was under Dick Mobley, Ron Currier and Al Guthke while John Grimson was responsible for the Beam dump. Rudy Nissen and Al Guthke developed the vacuum system while Dick Biwer, Les Oleksiuk, Fred Hornstra and Jon Sauer gave their attention to detectors. Helen Edwards helped with the tuning.

In addition to Maschke, design of the Switchyard system was performed by Les Oleksiuk, Dick Mobley, Bob Daniels, Claus Rode, John Simon and Herman Stredde. Bob Scherr, Ed Tilles, and Joe Otavka supervised construction of the many specially-designed magnets and control equipment needed for this highly-complicated system. Bill Vallas of DUSAF was the architect. The group, numbering 70 in peak periods, also included many other technicians and design personnel. They "delivered" the proton beam that experimenters were waiting for.

R. Andrews
R. Andrews
L. Bartelson
L. Bartelson
R. Biwer
R. Biwer
E. Bleser
E. Bleser
R. Currier
R. Currier
R. Daniels
R. Daniels
H. Edwards
H. Edwards
J. Grimson
J. Grimson
A. Guthke
A. Guthke
F. Hornstra
F. Hornstra
R. Krull
R. Krull
J. McCarthy
J. McCarthy
R. McCracken
R. McCracken
R. Mobley
R. Mobley
R. Nissen
R. Nissen
R. Oberholtzer
R. Oberholtzer
L. Oleksiuk
L. Oleksiuk
J. Otavka
J. Otavka
C. Rode
C. Rode
J. Sauer
J. Sauer
R. Scherr
R. Scherr
G. Simon
G. Simon
K. Sowinski
K. Sowinski
H. Stredde
H. Stredde
E. Tilles
E. Tilles
A. Visser
A. Visser
   

Source: The Village Crier Vol. 4 No. 17, April 27, 1972



SWITCHYARD GROUP READIES 3-WAY SPLIT

PROGRESS REPORT FOR JANUARY, 1973
During the month of January, in the course of a successful high energy physics run, an integrated exposure of 1017 protons was reached. The first beam splitting station was initially tested on Saturday, January 6. Injection of twelve Booster pulses for each Main Ring pulse became a regular mode of operation. The accelerator ran consistently at 1.8 X 1012 protons per pulse at 300 BeV.


The Switchyard group in NAL's Accelerator Section was never satisfied with the status. The modifications to improve operations of the accelerator, which were this group's responsibility, were tested on January 6, 1973. The first "splitting station" in the beam transport line successfully "sliced" the beam coming from the accelerator, sending 25% of it to the Proton experimental area and 75% to the neutrino experimental area, at the same time. The test run activated the first of two new splitting stations. The second station was installed during the week of January 28, 150 feet farther from the accelerator on the transport line, adding the Meson Area to the new arrangement and resulting now in a 3-way split capability. Station #2 was tested for operations. Further tuning of the new apparatus, together with related alignment work, continued for several weeks.

"We must still try for perfect splitting," said Les Oleksiuk, who led the January effort in the Switchyard group, "so as to not disturb beam trajectory. We want to cut the beam neatly and cleanly without affecting the beam spot."

Many Switchyard staff members were involved in the splitting station work. Claus Rode and Leon Bartelson handled cabling and control electronics; Les Oleksiuk was responsible for layout and beam optical design. Gene Fisk and Fred Hornstra worked on beam diagnostics and loss monitor. Design parameters of the Lambertson magnets were the results of a collaboration of Rode and Oleksiuk; Ed Bleser and Dick Andrews supervised the wire septum modules. Under Andrews' direction, Richard Krull and Butch Bianchi built, tested, and assembled the wire splitter.

This device in the beam transport line, was vital to the new beam splitting technique. It was built by NAL's Magnet Fabrication group
This device in the beam transport line, was vital to the new beam
splitting technique. It was built by NAL's Magnet Fabrication group
A close-up of the new Lambertson Septum which accomplishes beam splitting
A close-up of the new Lambertson Septum which accomplishes beam splitting

Two basic components accomplished the splitting action. The first was an electrostatic wire septum, composed of a 10 ft. array of parallel, hair-like, stretched tungsten wires surrounded on each side by strong electric fields. When the beam encountered this device, an effect similar to the peeling of an orange resulted - the tiny 2/1000" wires act like a knife edge, and the diverging electric fields provided the necessary wedging action to separate the beam into two distinct portions. Four-10 ft. wire septa were installed in the Switchyard complex, two in each of the splitting stations.

Once the beam was split into two portions, each portion goes in a different direction. Further splitting was accomplished by a special "Lambertson Septum" magnet, designed and built by the NAL Magnet Fabrication group under Will Hansen. This device provided a magnetic deflecting kick to one of the split portions of the beam, while simultaneously shielding the second portion from this deflecting force. In this way, a very strong "parting of the ways" occured between the two beams; about 1/2 degree in angle. From then on, each split portion acted like a distinct beam handled with the -usual type of bending and focusing magnets.

A special array of small bending magnets was used to "bump" the original beam on to the wire splitters; varying this "bump" allowed varying the splitting ratio between any two experimental areas. The needs of different experiments vary greatly. Some need many protons (high intensity with high energy, such as neutrino experiments. Others need less intensity of less energy. The more experiments that can be accommodated at one time, the more experimental work can be accomplished. In a sense, the duty factor of the machine was increased by 200% with the activation of the beam splitting feature since three experiment lines could operate at once, instead of one at a time.

Future splitting stations were designed for the Proton Experimental Area, and also for the Neutrino targeting areas.

Source: The Village Crier Vol. 5 No. 6, February 8, 1973