Building the Energy Doubler/Saver/Tevatron
Return to 1979 - 1989 - Tevatron
- Milestone: Switchyard operates refrigerator (June, 1978)
- Well done! (January, 1982)
- Noise, fog mean successful A-sector test (March, 1982)
- Tev I Antiproton Source moves ahead (March, 1982)
- No, it is not a new yellow wienermobile (October, 1982)
- E-F sector cooldown "looks good" for November (October, 1982)
- Work continues on Energy Saver (December, 1982)
- Begin Energy Saver/Doubler commission (December, 1982)
- Doubler developments (April, 1983)
- Saver reaches goal, sets energy record! (July, 1983)
Switchyard staffers have marked a milestone-the culmination of two years' work. The event was the first operation of a satellite helium refrigerator in the Switchyard. At the Switchyard, the proton beam from the Main Ring is directed to external target areas.
Project director Jeffrey Appel said, "This refrigerator is especially significant because it is the first satellite built from commercially-produced components. Equally important, elements in the system are common with elements which will be used in the Energy Doubler and Proton Laboratory satellite refrigerators."
He pointed out that the refrigerators supply -450°F cooling. This is required to make magnets in beam lines and the accelerator Main Ring superconducting.
According to Appel, the Switchyard refrigerator was producing reliquefied helium from gas a day after the start of the system's first cooldown. The Switchyard unit is intended for use in bringing 1 TeV (one trillion electron volts) proton beams to the external experimental areas when it becomes available. Its first use will be in a test of two Energy Doubler magnets to be installed in the beam line to the Meson Laboratory. Pending successful testing, the 56 conventional left bend magnets to Meson will be replaced with 22 Energy Doubler magnets.
Appel added, "The smooth beginning of operation was a result not only of the dedicated efforts of those manning the first run, but the careful work of a host of Laboratory employees." Playing key roles in the startup were engineers Richard Andrews, Jerry King, Robert Kolar and Chris Winter of the Switchyard group; Jerry Czop, Michael Hofmann, James Loskot, William Martin and Terry Savedra of Accelerator Mechanical Support Group.
In addition, the success would not have been possible without Alex Waller and Eric Getting, Controls Group; Bob Haring, Mechanical Support Group; Jack McCarthy, Robert "O.B." Oberholtzer and Sharon Lackey of Switchyard; and many others in the procurement, welding and machine shop groups.
Source: FermiNews Vol. 1 No. 5, June 8, 1978
under conventional magnets in Main Ring tunnel
...was the accolade with which Accelerator Division Head Rich Orr and Deputy Head Helen Edwards greeted the troops emerging from the Main Ring tunnel as the six-month shutdown of the accelerator came to an end. Some of the "tunnel rats" had not seen daylight for weeks, coming in early and leaving late with the entire day spent in the tunnel.
There was much to show for their efforts. Linac Group Head Cy Curtis could point to a new, sophisticated microprocessor-based control system designed by the group led by Mike Shea.
Booster Group Head Curt Owen had stolen a march on the main accelerator by doing early testing of improvements in the Booster systems and was gratified to see a new record of 4.3xl013 protons from the Booster in the equivalent of one Main Ring cycle. Improvements in the 8-GeV line from the Booster to the Main Ring should enhance the transmission between the two machines leading to improved performance of the Main Ring.
from the Main Ring and inject it into the Energy Saver
In the Main Ring, primary emphasis was on the installation of Energy Saver components under the direction of Accelerator Systems Group Head Peter Limon, ably supported by groups under Larry Sauer and Max Palmer. By the end of the shutdown they could "point with pride" to having the Al, A2, and A3 cry loops installed, vacuum tight, and ready for cooldown. Coupled with the work of the Controls Group under Dixon Bogert, the two Refrigeration Groups under Claus Rode and Dick Andrews, the Central Helium Liquefier Group under Ron Walker, and the Power Supply Group under Gerry Tool, this installation is the final major test of the Energy Saver. It involves 118 superconducting magnets, three satellite refrigerators and the Central Helium Liquefier, the 5000 amp power supply, and the full control system.
section of transfer and high pressure helium line
While all this was going on in A-sector, preparatory work was being carried out in the rest of the ring. At the E0 straight section Mike Harrison and the Conventional Devices Group under George Biallas installed the complicated system of magnets and kickers needed to inject the beam into the Saver from the Main Ring. The compressor stations at E0 and F0, with four helium compressors each, were commissioned under Dick Andrews. Ed Kessler of the Electrical Support Group directed the installation of hundreds of miles of cable around the ring. With the accelerator turned off, the Operations Group under Bob Mau turned to Saver installation. Bill Merz oversaw installation of many miles of copper control tubing needed for the full Saver. Duane Plant and Debra Baddorf saw to terminating the cabling for A, E, and F-sectors, involving 10,000 connections per sector.
Main Ring berm (see aerial photograph on preceding page)
By the end of the shutdown, besides having the Main Ring ready for 400-GeV operation, the Accelerator Division, with generous assistance from many elements of the Research Division and various Laboratory support groups had 3 (of 24 total) cryoloops of the Saver ready for operation; 15,000 out of 22,000 feet of transfer and high pressure helium lines were completed on top of the berm, thanks to Don Richied and the Paramount Park crew and the leak-checking crews under Mark Leininger; all of the 24 refrigeration buildings and Service Building Controls enclosures were complete; 18,000 of 22,000 feet of helium and nitrogen collection piping were installed in the tunnel; all of the cable trays and pneumatic tubing for the entire project were in place; the cabling for half of the Ring was complete; in addition to the A-sector magnet installation, 90 additional dipoles selected by Don Edwards and Leo Michelotti were installed in the El, E2, and F4 cryoloops.
Back on the assembly front, Dick Lundy's people in Industrial Buildings 1 and 3 had reached an assembly rate of 12 dipoles per week; the Magnet Test Facility under Frank Turkot achieved a rate of 14 magnets/week; and at Lab 5 Del Miller's crew completed cryostat assembly and turned their attention to spool pieces, while the crew at Lab 2 under Al McInturff set up a spool-piece measuring facility.
Not to be outdone, Quentin Kerns' RF Group completed the first of the three radiofrequency cavities for the Saver.
Source: FermiNews, January 7, 1982
M. Hentges (at keyboard), P. Martin, G. Tool, D. Wolff,
L. Lederman (standing), and P. Limon (background)
At approximately 3:30 p.m. Friday, February 19, the denizens of the east side of Wilson Hall were treated to a dramatic demonstration of the progress of the Energy Saver project. In the first major power test of the Energy Saver, all the A-sector magnets were successfully energized to a level corresponding to operation at 500 GeV and ramped to that level for 1-½ hours at a 72-second repetition rate. Before proceeding to higher levels, a "worst-case" test was given the sophisticated systems designed to rapidly remove the stored energy from the magnets in a controlled manner and to relieve the pressure built up in the helium. This procedure involved making all 94 dipoles in the system go normal (non-superconducting) at once by firing heaters in the magnets. The energy stored in the magnets dissipates by boiling the liquid helium used to keep them cold. The noise and fog seen from Wilson Hall were caused by cold helium gas escaping from relief valves on top of the refrigerators.
This spectacular success was accomplished through weeks of around-the-clock effort on the part of Saver and support group personnel who labored through a long summer and fall to install magnets, power supplies, refrigeration, controls, and associated equipment in the Al, A2, and A3 cryoloops - 118 magnets, 25 spool pieces, 3 refrigerators, and 4 compressors - plus the Central Helium Liquefier. Behind the opportunity to install and test are years of R&D, testing, and fabrication effort by the dedicated workers of Fermilab. In addition to the efforts of the Energy Saver, many people of the Laboratory devoted much time over the past several years to get us to where we are now. Included among these are the Proton and Meson Departments, the Bubble Chamber groups, people at Paramount Warehouse who built cryogenic components, and the Neutrino Department, Research Services, Radiation Physics, and the Physics Department who helped with electronics, power supplies, and the controls effort.
The operating groups of the Accelerator Division - the Main Ring, Booster, Linac, and Switchyard Groups - and the accelerator operators were of inestimable help in assembling and operating the Saver tests. Much of the R&D and fabrication work, and many of the tests are being carried out by the Accelerator Support Groups, particularly the Controls, Electrical, and Instrumentation Groups. The magnets were put into the tunnel and made leak-tight through the dedicated work and long hours of the Mechanical Support and Conventional Mechanical Devices Groups.
Through January the staff of the Energy Saver struggled to understand and master for the first time the simultaneous operation of three satellite refrigerators, compressors, and the vacuum system from the Main Control Room. The remote operation of this complex, interconnected system is made possible by the use of many microprocessors and computers, working in concert because of the heroic efforts of the Accelerator Controls Group.
After about two weeks were spent attempting to fill the 2400-foot string of magnets with liquid helium using only the three satellite refrigerators, the Central Helium Liquefier was put on line. Within six hours the magnets started to fill, and ten hours later the system, about one-eighth of the complete Energy Saver, was filled with liquid helium and ready to be powered. The Central Helium Liquefier, the largest in the world, performed even better than it was designed to do.
Now it was the turn of the Power Supply Group to prepare for the crucial test of bringing the magnets up to a current of thousands of amperes as the first step toward the current of 4440 amperes that gives the magic current of 1 TeV. Enormous forces are involved at these high energies so each step must be carefully planned and its consequences studied before proceeding to the next step.
After the data from Friday's spectacular quench are all carefully evaluated, the current will be raised step by step until the planned operating mode for the Tevatron is achieved. Prosit!
Editor's Note: On Tuesday night, February 23, the A-sector test current was raised to the equivalent of 600 GeV.
Source: FermiNews, March 4, 1982
The people of the Antiproton Source Section have been very busy and productive in the last several months. Their hard work culminated in a Design Report issued just before the beginning of March, a detailed cost estimate of the entire project, and two intensive reviews of the project. Everyone in the section had a hand in these events, under the leadership of John Peoples, Don Young, and Fred Mills. Sue Grommes of the Director's Office and Teri Martin typed endless drafts, giving the CYBER word-processing system one of its tougher workouts.
In addition to the antiproton source, the Tevatron I project includes additional refrigeration, special magnets, and rf systems to make the Energy Saver into a 1-TeV (trillion electron volt) accelerator and storage ring, the Tevatron, as well as building and conventional facilities at B0 for the Collider Detector. But the centerpiece of the project is producing and accumulating antiprotons, then accelerating them to 1 TeV going the other way around the Main Ring and Tevatron, so that bunches of 1-TeV protons and bunches of 1-TeV antiprotons collide in the detector. The goal is to produce and study the elusive "intermediate bosons," the W and Z particles, that will be a large step toward a more complete picture of the elementary particles we study at Fermilab.
What is presented in the new Design Report is a completely new design making use of "stochastic" cooling to shrink the antiproton beam to a tighter size so that it will fit in the Main Ring and Saver and to make more collisions. The old design, done a year ago, needed 12 hours to collect enough antiprotons to reach the luminosity goal (lO30cm-2sec-1) the designers set for themselves. The luminosity is a measure of how many events collisions will produce. The new design does the job in less than 5 hours. It also has better ways of being expanded to higher luminosities as we learn how to use them.
The new design includes a new target station to produce 8-GeV antiprotons from 125-GeV protons. The antiprotons are injected into a Debuncher ring to be built south of the Booster. In it, the beam will be given some initial cooling, then transferred to an Accumulator ring concentric with the Debuncher. Here we will stack successive batches of antiprotons, cooling them with 6 separate stochastic systems, until there is enough beam cooled to a high enough density. Then the antiprotons will be taken out and accelerated in the Main Ring and Tevatron.
The new better performance doesn't come for nothing. The estimated cost of the Tevatron I project has gone up. But it is a better, more solid project. Two review committees have examined the design in great detail. The first, a group put together by Leon Lederman to advise him, endorsed the project as sound technically. The second, a Department of Energy Committee, led by Maury Tigner, met here all last week. Their report is not available as yet, but the Fermilab antiproton people feel we did a good job of defending our work.
The schedule calls for beginning construction work this summer at B0, to mesh with the Energy Saver schedule, then to begin building the Antiproton Source next fiscal year. It won't be easy - the schedule is tight and there are many technical components to build and assemble, but the goal of proton-antiproton collisions at 2 TeV, the highest energy in the world through at least the 1980's, keeps the Antiproton Source Section working hard to get there.
Source: FermiNews, March 18, 1982
In case you are wondering about the large yellow objects lurking behind the Main Ring shielding berm near the Central Helium Liquefier, they are not Oscar Mayer wieners (although some of Claus Rode's people were apprehended making a stealthy approach along the Main Ring Road in possession of an "Oscar Mayer" stencil). The 13 tanks will store the entire inventory of helium gas for the Energy Saver, the equivalent of 13,000 gallons of liquid helium. The delivery of the tanks after an eventful journey(s) from Texas meant one more major piece had fallen into place in preparation for the next exercise in bringing the Energy Saver into operation.
While the helium tanks are a very visible sign of progress towards the goal of a half-ring test, enormous progress has also been made out of sight in the Main Ring tunnel and the service and refrigerator buildings. Over 60% of the full complement of superconducting dipoles and quadrupoles have been installed in the tunnel and surveyed in place within a few thousandths of an inch. In E and F sectors 4 (of 8) cryoloops, consisting of 40 magnets each, are vacuum tight. The goal is to have all 8 cryoloops in E and F sectors ready to cool down to superconducting temperatures in November.
While much effort and attention focuses on the superconducting magnets, they are only one ingredient in making a superconducting accelerator. A helium transfer line delivers the liquid helium and liquid nitrogen from the Central Helium Liquefier (CHL) to the 24 refrigerator stations around the circumference of the Main Ring; 4-½ miles of transfer line from CHL around the entire ring and back to CHL are now complete and will be delivering liquid helium at 450°F below zero and liquid nitrogen at -330°F before the November target.
Bruce Kling purges the pneumatic control system in the Main Ring tunnel
A contract electrician installs control cable at E4
Dave Augustine adjusts a leak detector used to test Energy Saver magnets
Hundreds of miles of cables have been installed and carefully checked for monitoring and controlling the myriad critical points of the system. One of the 8 refrigerator systems involved in the E and F sectors sends back as many data points as the entire 500-GeV conventional accelerator did. Ultimately there will be 24 such refrigeration systems. Only the expansion engines themselves, being given last minute adjustment in the Cross Gallery, remain to be installed by the target date.
To control all of this, the new VAX computer systems are being brought online. The VAX is more powerful and sophisticated than the Xerox XDS530 computers used for the accelerator control and monitoring until now. This increased power is bought at the price of a vastly more complicated programming effort. One of the major efforts in the start up of the two sectors is the programming readiness.
Finally, the November tests will involve the preliminary tests of the final power-supply configuration. Massive 2 in. x 2 in. copper bus salvaged from the Chicago Cyclotron magnet is used to bus the power supplies to the magnets. A major effort is installation of 4 complete power supply systems at E2, E3, F2, F3 service buildings. By the time the supermagnets are cold and superconducting, these systems will be ready to power the magnets. Meanwhile the injection system to transfer the proton beam from the Main Ring to the Energy Saver has been installed at E0 and successfully tested.
The Accelerator Division has been heavily supported by the Technical Division and the Research Division in all of these efforts. Once the two sector tests begin the system will be further strained as personnel struggle to master the very complicated operational systems at the same time installation work continues in B, C, D sectors to complete the entire Energy Saver complex.
It is an exciting period for the Laboratory as nearly eight years of sustained effort now moves swiftly to fruition, moving towards the goal of 1 TeV.
Source: FermiNews, October 14, 1982
E, F SECTOR INSTALLATION COMPLETE
in the Main Ring tunnel. This photograph
shows the often cramped conditions that
are typical of many jobs performed in the
close confines of the tunnel.
(Click on the drawing for a larger view)
...the Saver must take first priority. This establishes the superconducting ring of magnets and is the key to the future of the Laboratory. L. Lederman
by Thornton Murphy
At 5:45 p.m. Friday, November 19, Sectors E and F of the Energy Saver, one-third of the ring, switched from "installation mode" to "operation mode." The event which so clearly marked this transition was the changing of the locks on all the doors leading to E and F Sectors. Since June, several hundred people have held keys to these doors to permit rapid entry to the large installation team. On November 19, the locks were changed back to safety system locks. At the same time, responsibility for coordination of activities in this part of the ring passed from the Accelerator Systems Department to the Accelerator Operations Group.
This event was met with jubilation by the couple hundred people who have labored under pressure since June to finish the installation. Now the Accelerator Operations Group, the Cryogenic Systems Group, the Central Helium Liquefier, and the Electrical Support and Controls Group are in the "hot seat," as they work around the clock to complete safety checkouts and cool the two sectors to liquid helium temperature. They are scrambling to meet a late December goal to power E and F sectors to full current. On the following pages are photographs by the Fermilab Photo Unit documenting myriad installation tasks which have so happily concluded in one-third of the ring.
SCORES SPEND LABORIOUS MONTHS IN MAIN RING TUNNEL TO BUILD ENERGY SAVER/DOUBLER
Harry Krider, a Belding employee, stacks magnets at D0 prior to being lowered into the tunnel for installation
Rodney Shores sprays helium on a magnet interface to check for leaks
Gary Capola (kneeling) and Terry Guthke use surveying techniques to align a Doubler magnet to within a few thousandths of an inch
Russ Harrison connects cryogenic lines between magnets
Merill Albertus (standing), Ken Meissner (foreground), Rine DeKing, and Gene Witt install a superconducting dipole magnet under a Main Ring magnet by gently sliding it into place
Using a chart recorder, Roger Thomas reads output from six leak detectors placed 100 feet apart
"The Saver is our key to a solid future. It is essential for both scientific and energy saving reasons...1983 is the light at the end of our tunnel!"
"People with skill and expertise in diverse groups will be asked to take on Saver-related projects and to carry these out with the same love and dedication as they put on their own specialties. This is because the future of Fermilab hinges on this plan. If we survive the dangers of schizophrenia and carry it off we will be the pre-eminent laboratory in the world."
Source: FermiNews, December 2, 1982
November 19, 1982 marked the beginning of efforts to cool down and operate the E and F Sectors of the new Saver superconducting accelerator. This test is the beginning of the Saver commissioning.
Last winter and spring one-eighth of the Saver ring was tested. Included in the test were 2 compressor buildings (A0 and B0), 3 refrigerators (Al, A2, and A3), 2 miles of transfer line, and 2700 feet of superconducting magnets. By comparison, the E and F Sector test is a one-third ring test consisting of 3 compressor buildings, 8 refrigerators, the complete 4-mile transfer line, and 7200 feet of the accelerator. The two sectors include 258 dipoles, 80 quadrupoles, and about 100 other tunnel components.
The goals of this test are well defined. Successful operation of the controls system, refrigerator and compressor reliability, power supply performance, and the quench protection monitoring system communication are complex tasks that have added to the excitement around the Main Control Room during the last few weeks.
(Click on the drawing for a larger view)
During November the F0, E0, and A0 compressor buildings were started up, liquid nitrogen transfer from the Central Helium Liquefier was begun, and the VAX/PDP-11 computers were integrated into the controls system. By December 1 the system was operating on pure helium and on December 3 cool down of both E and F Sectors was begun.
This test is crucial for the controls system. With the knowledge obtained from the A-Sector test several improvements in the algorithms to control the refrigerators and compressors have been made and will now be fully tested. One goal is to have a fully automatic system by the end of the test. The task is far from easy; with two sectors working and three compressor buildings and the Central Helium Liquefier in operation, 53 feedback control loops must work in harmony. This number will steadily increase as the rest of the ring becomes operational. Upon completion of the Saver commissioning, there will be 353 control loops in operation.
A second goal for the controls system is to have a "system" approach to the controls of the compressors to avoid possible oscillations in the transfer line. The compressor controls will be centralized using the VAX system instead of only using distributed intelligence residing in the microprocessors that control each of the compressor houses.
Manuel Martin at the Saver control console recalculating parameters
for loop controls for compressors
The power supply and quench protection tests in E and F Sectors will take on a considerably different flavor than they had during the A-Sector test earlier this year. The A-Sector test included attempts to stress the components to their worst-case conditions. This winter, the approach is one of kid gloves, not a sledge hammer. Any spectacular, large-scale quenches will be unscheduled.
The system has grown considerably in complexity in moving to one-third ring testing. There are four 1 kV power supplies in use, and 8 quench protection monitors communicating through a new link that is in place around the ring. There was much activity both in the service buildings readying the hardware and in the software development. The magnets are full of liquid helium and have successfully been hipotted, and the cables between the superconducting bus and the quench protection hardware have been connected. The plans include controlled tests of failure modes, a few detailed studies of certain aspects of the quench protection system, and attempts at extended periods of ramping.
It's the beginning of new and exciting things for Fermilab. We're breaking new ground every day.
Source: FermiNews, December 16, 1982
Fermilab takes possession of the Collider Detector Pit!
Rich Orr (left), John Peoples, and Tim Toohig (center) raise
the flag in front of the giant sliding door that is an essential
feature of the Pit
The recommissioning of the Main Ring and start-up of the Energy Saver/Doubler are proceeding exactly on schedule. On Saturday, April 16, 1983, Sectors E and F of the Saver (1/3 of the ring) were powered to 2200 amps, equivalent to 500 GeV. On the following day, beam in the Main Ring was accelerated to 150 GeV, the energy necessary for injection into the Saver.
On Friday, April 22, beam was injected from the Main Ring into the Energy Saver at the E0 straight section. After 19 hours of tuning, a low-intensity beam in the Saver was transported 1/3 of the way around the ring to a beam dump in A0. Although fine-tuning will continue in both rings every weekend, the next major milestone will be completion of the Saver installation so that complete revolutions with beam can be attempted.
The new beam position monitoring (BPM) and beam loss monitoring (BLM) systems were tested with beam for the first time and performed beautifully. Dramatic computer-generated color displays showed the location of the beam in the Energy Saver vacuum pipe to a precision of 1 mm over the 2 km distance. The digital information from the BLM's was used to automatically adjust the correction dipoles to smooth the orbit.
Source: FermiNews, April 28, 1983
by Thornton Murphy
The Energy Saver has reached its primary design goal: accelerating protons to 500 GeV in a ring of superconducting magnets. In fact, the energy was 512 GeV--a new world record for accelerators. The record was set at 3:37 p.m., Sunday, July 3, only 13 hours after the first serious attempt to accelerate beam above the injection energy of 150 GeV.
News of this historic achievement spread rapidly-by telephone and telex to all quarters of the world. The Control Room rapidly filled with off-shift workers and other well-wishers as the champagne was broken out.
The events leading up to this milestone followed the usual pattern of a long pause while a blockade to progress was diagnosed, followed by sudden leaps forward. Difficulties in achieving coasting beam at 150 GeV, reported two weeks ago, were finally tracked to a misdesigned flange in the C0 straight section and a Kimwipe left in the bore tube in A0. After the Kimwipe was removed on June 25, coasting beam was rapidly achieved. The rf cavities were proven capable of maintaining the bunching at 150 GeV and even accelerated the beam slightly.
Director Leon Lederman pours champagne for Linda Klamp as she
"spreads the news" on Sunday, July 3
There followed a two-day down period for necessary repairs with the expectation that acceleration towards 500 GeV would begin soon after startup on June 30. Unfortunately, the weather did not cooperate. A lightning bolt struck service building E0 at 3 a.m. on Friday, July 1, damaging enough sensitive electronics to cause six hours of diagnosis and repairs, followed immediately by more lightning-induced trips around 9:30 a.m. The next night torrential rains found their way all the way to electronics racks.
When all was finally ready to attempt acceleration, beam reached the top of the 250 GeV ramp on the very first pulse at 3:12 a.m., Sunday, July 3. After a shift of studies at that energy, the current ramp in the magnets was reset to 400 GeV and beam accelerated to that energy at 1:38 p.m. A "go for the record" spirit then prevailed; after readjusting the ramp again, the energy goal was exceeded amidst jubilation at 3:37 p.m.
As this issue goes to press, the Doubler is holding at 512 GeV and low intensity to make systematic measurements of beam characteristics. The energy is already more than needed for the 400-GeV run for physics experiments scheduled for October of this year. The next important tasks for the Doubler are to increase the intensity and master extraction of a high intensity beam to the Experimental Areas. Rich Orr commented, "We are sweating blood to make our end work. I hope the experimenters will be ready in the fall - although we still have a long way to go.
At its Friday, June 17, meeting at Fermilab, the Universities Research Association (URA) Board of Trustees voted by acclamation the following expression of recognition of the Laboratory's attainment of an initial beam in the superconducting ring:
"Be it resolved that the Board of Trustees of the Universities Research Association congratulates the Director and staff of the Fermi National Accelerator Laboratory for reaching an impressive milestone of the Saver project in record time. In particular we wish to acknowledge the singular accomplishments of Dr. Rich Orr and Dr. Helen T. Edwards in leading this distinguished effort."
This was submitted to Leon Lederman by Dr. H. Guyford Stever, president of URA, in a letter dated June 23.
Source: FermiNews, July 7, 1983