Oral-History:Lawrence Johnston
About Lawrence Johnston
Johnston received his BA in Physics in 1940 from the University of California, Berkeley, then started to study as a Physics grad student at the same university. An acolyte of Luis Alvarez, he studied under his as an undergrad, was his lab assistant at Berkeley as a grad student, helped him work at the Berkeley cyclotron, followed him to the Rad Lab in January 1941, worked for him at the Rad Lab, particularly as project engineer for the blind-landing GCA project, followed him to Los Alamos in 1943, and followed him back to Berkeley at the end of the war. Johnston also worked on installing radar in the B-18 and A-20 bombers. His biggest contribution to the GCA system was the data handling. There was some resistance by the Rad Labbers to his leaving for Los Alamos. He noted a falling off in the Rad Lab esprit de corps when he returned for a visit in 1944. Since the war he has basically been a physics graduate student and professor.
About the Interview
LAWRENCE JOHNSTON: An Interview Conducted by Frederik Nebeker IEEE History Center, 13 June 1991
Interview # 094 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc. and Rutgers, The State University of New Jersey
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It is recommended that this oral history be cited as follows:
Lawrence Johnston, an oral history conducted in 1991 by Frederik Nebeker, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.
Interview
Interview: Lawrence Johnston
Interviewer: Frederik Nebeker
Date: 13 June 1991
Location: Boston, Massachusetts
Education and Family
Nebeker:
This is interview with Larry Johnston on the 13th of June 1991 in Boston. The interviewer is Rik Nebeker. Before asking you about Rad Lab, I'd like to ask you first about your education and experience. Where did you get your undergraduate degree?
Johnston:
I got my undergraduate degree at Berkeley.
Nebeker:
In physics?
Johnston:
In physics. But the first two years I went to Los Angeles City College, which I think worked out really very well.
Nebeker:
Were you a native of Los Angeles?
Johnston:
I was living in Los Angeles, yes. My parents had been missionaries in China, and later my father was a pastor, and we moved around to several towns in California.
Nebeker:
I see.
Johnston:
We wound up in Los Angeles, in the middle of the great depression, and we were poor as church mice. I was very happy to be able to start my education at LA City College. There was a very good physics professor there, who said, "You really ought to go to Cal because Ernest Lawrence has just invented the cyclotron up there. Nuclear physics is going gangbusters."
Nebeker:
What year was it? Oh, I can see here. It was in 1940 that you completed your degree?
Johnston:
So I completed my degree then at Berkeley. But I found that people were a lot more interested in doing a good job of teaching at the City College. What was fun at Berkeley was to hear in class "guess what happened at the radiation laboratory last night."
Nebeker:
Did you have any contact with the Berkeley Radiation Laboratory in your undergraduate days?
Johnston:
Yes. Have you heard of Luis Alvarez?
Nebeker:
Sure.
Johnston:
I took one of his classes and was immediately entranced.
Nebeker:
What was the course in?
Johnston:
I believe it was called "modern physics." In other words, everything that had happened since the turn of the century. It was mostly related to quantum mechanics.
Nebeker:
Relativity?
Johnston:
Relativity and radioactivity. He had a very exciting way of talking about things. He would mention: "Sorry I'm bleary-eyed, but we were up all night trying to get the cyclotron going." He invited me to come to the old Radiation Laboratory, which was down on the campus, a wooden building. It doesn't exist now, but I recently found a brass plaque in one of the buildings nearby saying, "This is approximately where the old Radiation Laboratory stood." I remember the first evening I opened the door a crack and looked in there, and the staff was having a meeting. Luis Alvarez motioned to me, "Come on in." There on a blackboard was a cryptic message that said: "For Sale, Cheap: One Oscillator Tube, Model Niagara." [Chuckling] They made their own vacuum tubes in those days to run the cyclotron, high-powered oscillators that were continuously pumped on a vacuum system. The grid was made of copper tubing, and it had melted through and flooded the vacuum system. So that was my introduction.
Nebeker:
Did you then get steered toward nuclear physics?
Johnston:
Yes. That's what was going on. I think artificial radioactivity had just been discovered. They were feeling embarrassed that it had been discovered in Europe using very rudimentary equipment. Their whole laboratory was just buzzing with radioactivity, and they had missed it.
The Radiation Laboratory
Arrival
Nebeker:
So you graduated in 1940. What did you do then?
Johnston:
I graduated in the middle of 1940, and then I started graduate work at Berkeley. Luis Alvarez chose me as a lab assistant in the modern physics laboratory course. In November he went to this famous meeting at MIT. Ernest Lawrence had called all the nuclear physicists that he knew to come to this meeting. He asked me to take charge of his laboratory while he was gone. Then in December he phoned me from MIT, saying "we need you here on a very important war-related project."
Nebeker:
According to this you came in January of '41 to the Rad Lab, is that right?
Johnston:
Yes. What kind of a source do you have?
Nebeker:
This is just the page from the Radiation Laboratory Directory that was put out just after the war.
Johnston:
Yes. That is the most knowledgeable list that exists, I think.
Nebeker:
Well, it's very good in giving the assignments at Rad Lab. What did Alvarez tell you about this position that he was offering you?
Johnston:
When he left, he said this was going to be "something big." He didn't say what it was going to be.
Nebeker:
Did you know about radar, the possibility of radar?
Johnston:
No. I thought that it was going to be a nuclear energy project.
Nebeker:
And it was called Radiation Laboratory at that time?
Johnston:
Yes, but I didn't even know that at the time. I just knew that when I got to MIT, I should look for Room 4-133.
Nebeker:
There was no question in your mind of accepting this rather than continuing your graduate work?
Johnston:
That's right. I really appreciated Luis Alvarez. He spoke for God as far as my career choices were concerned. So if he and Ed McMillan and some of those people were going to be there, that's where I wanted to be.
Nebeker:
You made the move fairly quickly out here in January?
Johnston:
I drove Luis Alvarez's car out. He had thought he was just going to go there temporarily. So now he said, "As long as you're coming, you can drive my car out."
Nebeker:
Do you remember how long that took you to get across the country?
Johnston:
About a week. A few hundred miles a day.
Nebeker:
That must have been an experience then, a cross-country trip. Were you traveling alone?
Johnston:
I was traveling alone, yes.
Nebeker:
Tell me what you recall of your arrival at Rad Lab. I know it was just some offices at that point, but how did your first days go.
Johnston:
I pulled up in front of MIT and couldn't tell where to put the car.
Nebeker:
Maybe it wasn't such a problem then.
Johnston:
I guess not. I walked in these very pretentious doors at the front underneath the dome, and there were some photoelectrically operated doors. My goodness! Of course every grocery store has them now. [Chuckling] But that was automation, at least for me. I asked somebody where Room 4-133 is. Oh, just follow those people down the corridor. There was a sign saying "Building 4 This Way," but the hallway was blocked off, and there was a door and a desk outside and a guard. So I said, "I'm looking for Luis Alvarez." He said, "Sit down." He was a very friendly sort of a fellow. His name was Haller. Soon Alvarez appeared and started showing me around.
Nebeker:
Were you immediately briefed on what was going on and what was planned?
Johnston:
Yes. We had two floors there. On the ground floor, we walked down the hallway and into a lab. In the lab there was a spiral staircase that went up into an upper lab. There wasn't much space to sit down, but we found a corner, and he started telling me about what was going on.
Power Supply for Klystron Beacon System
Nebeker:
What was your initial assignment?
Johnston:
The first thing he asked me to do was to work on some beacons. He was putting together a klystron beacon system. So he said, "We've been running all this equipment on batteries. Would you make an a.c. power supply for this thing?" I went to the stockroom and found everything I needed to make an a.c.-operated power supply.
Nebeker:
Did you have much experience with electronics?
Johnston:
Yes, I had a great deal of interest in radio early on. And at the [Berkeley] Radiation Lab, when they built a new 60-inch cyclotron for medical purposes pretty close to the old wooden Radiation Lab. It was on a very low budget, and each of the professors and staff members working there took on some aspect of this. Wynn Salisbury built the oscillators. He's the guy that built the model Niagara vacuum tubes. Luis Alvarez was responsible for the controllers for the ion-type vacuum gauges. There were many vacuum systems there. He asked me to build the electronic units that ran the ionization gauges. It was by far the most complex thing I had ever undertaken.
Nebeker:
He knew that you could do work of that sort.
Johnston:
He must have asked me if I had had any experience with radios. It worked out just fine.
Nebeker:
How did that first work go? You built the power supply for those beacons?
Johnston:
Yes, I built the power supplies, and I later built a modulator to turn the beacons on and off, to make some dots and dashes to identify which beacon station it was, using vacuum tubes. I never did hear what happened to that system.
Radar for B-18 and A-20 Planes
Nebeker:
What was that B-18, that system that you worked on? I'm just looking at this notation here from January to March '41. It's got "Installation of B-18"?
Johnston:
Yes, I think I helped to put together the hardware for the B-18 system.
Nebeker:
What is the B-18?
Johnston:
The B-18 is a bomber, one of the major two-engine bombers of World War II. Ed McMillan was in charge of that radar. I was soon asked to take on a project of my own, installing a radar in an A-20 attack bomber. That was essentially my project.
Nebeker:
The resume says from March until August of '41 is "Installation and development of the A-20."
Johnston:
Yes, that was a major job on the A-20.
Nebeker:
What were you doing with this?
Johnston:
One of the early jobs taken on by the Rad Lab was the night fighter. They got a dozen sets of equipment. They got various companies to build the magnetrons, the modulators, and receivers for a dozen sets. So I got one of these sets of equipment and built a mock-up of the cockpit of an A-20 plane up on the roof in the upper story of Building 6, perhaps. One of the plywood buildings. I would find places to hang the components within the plywood mock-up.
Nebeker:
You knew the exact dimensions of the cockpit and what space was available in it?
Johnston:
Yes. We had the blueprints for the plane. I just made sections like frames in the fuselage of a plane. That project never did amount to very much, because about then the British Battle of Britain was pretty much won with their own radar. So I took this equipment to Wright Field, where an A-20 was supposed to be waiting for me to install it. But they kept putting it off and diverting the planes to other purposes.
Nebeker:
Where is Wright Field?
Johnston:
It's at Dayton, Ohio. It's now Wright-Patterson Air Development Center, I think.
Nebeker:
And you were out there for a month?
Johnston:
I was out there for a month. I requisitioned equipment, for example a set of storage batteries. Everything ran on storage batteries for the plane systems. So I put the thing together there and ran it and saw that I could see signals. Every day I would go out there, and if anyone was interested, I'd show them what it would do. Finally I left because it was obvious the A-20 was not going to be delivered for a while.
Nebeker:
What's the explanation? They decided they didn't want to install those units in the A-20s after all?
Johnston:
I think the priority just went way, way down. I've heard that the system did later get installed in an A-20. This is told in one of the radar books; this is the way I learned about it. [Chuckling] Nobody ever told me. They had tried it out to see if it worked and apparently it worked.
Nebeker:
Were you showing the system to Air Corps people there?
Johnston:
Yes. There was a Colonel Yeager there who I was supposed to report to. He was pretty hard to see.
Nebeker:
Not Chuck Yeager?
Johnston:
No, not Chuck Yeager. [Chuckling] He might be a relative. He came and saw it once.
Nebeker:
Were you showing these people in hopes that they would then be more interested in getting it installed?
Johnston:
No, just as a matter of curiosity, because I had a definite mission to install it in the plane.
Nebeker:
The plane just didn't come.
Johnston:
I don't remember any security problems. What I wondered was, "Do I just show it to anybody that comes along?" Because I don't believe it was a secure area.
Nebeker:
Did you feel much constrained by security regulations in your work at Rad Lab?
Johnston:
Quite a bit, yes. Luis impressed that on all of our people very strongly.
Nebeker:
Did that constrain conversations within Rad Lab? Could you talk with anyone in Rad Lab about what you were doing?
Johnston:
Oh, yes. It was just a complete diffusion of knowledge within this group of people. They ate together and did everything together. There was a weekly meeting at which Lee DuBridge would give us a summary of the progress of the week and what was needed for next week. You really had a sense of the ongoing nature of things and a sense of purpose I hardly ever experienced anywhere else.
Growth of Rad Lab
Nebeker:
You were one of the early employees. What was the size of Rad Lab when you arrived? Do you have an impression of that?
Johnston:
I would guess about 50 people.
Nebeker:
Of course, it continued to grow, and grew very rapidly in '42.
Johnston:
Yes. Everybody was recruiting their old colleagues back at their colleges. I remember when we started GCA. Am I getting to far out of sequence?
Nebeker:
I was actually just going to ask you if we had then completed this A-20 work by August of '41. Does that seem right?
Johnston:
Yes.
Blind-Landing Project
Nebeker:
And then you started on GCA?
Johnston:
Yes. Let's see. Alvarez had a gallbladder operation that took him out of business for quite a while, while I was at Wright Field. Tom Bonner, another nuclear physicist, took over the administration of his group. When I came back to Rad Lab, I forget exactly what I was doing, but Alvarez came back very shortly and was excited about blind landing.
Nebeker:
Was it taken for granted that you would work on the project that Alvarez was working on?
Johnston:
Yes. None of us questioned that.
Nebeker:
And you had no problem with that, I take it.
Johnston:
Not at all. He was a very inspiring person to be around.
Nebeker:
Were you project engineer for the GCA blind landing system?
Johnston:
Yes. He immediately put me in charge of this blind-landing project. It was difficult for me because he then started recruiting his former colleagues from the University of Chicago and people that he had known as graduate students who had later gone to other places. These guys that I was supposed to direct were all Ph.D.'s, and here I was just a beginning graduate student, and five to ten years younger than they. Luis said "Oh, you'll have no trouble, they will all pitch in, and I'll back you up." All these predictions turned out to be true, and it was a great experience.
Alvarez had several other projects going, but GCA and MEW were the most successful. He kept a very active interest in the details of the system as it went together. My biggest contribution to the design was the data-handling of the system. This involved creating a theoretical glidepath trajectory for planes landing at that particular runway, and then comparing the plane's present (radar) position to the ideal. The difference was then presented to the Controller person as an error signal, which he used to give vocal correction information to the pilot, over the radio.
Nebeker:
How was that actually done?
Johnston:
Luis Alvarez's original plan for making a blind landing system assumed that there already existed a radar set which would accurately give 3-d coordinates on the plane coming in for a landing. This radar was the famous 584 gun-laying set. We expected to simply park a 584 radar beside an airport runway and use it to track an incoming friendly plane, so that we could give the pilot precise corrections to his trajectory and he could make a safe landing. All we would need to add to the 584 would be a data-handling system to accomplish blind landing.
The system I developed for doing this used two large mechanical cams to hold the 3-d information for the ideal glide path. Range information made the cams turn on their shaft, and azimuth information was represented by the radius of one cam, at each cam angle. The other cam displayed range versus elevation angle, for the ideal glide path.
Nebeker:
The cam controls one of those angles?
Johnston:
Yes. Each cam controlled one of the angles. The cam then was turned by the range of the plane coming in, and that told the azimuth or elevation angle of the ideal glide path. We compared that with the actual location of the plane, and that gave us an error signal. That signal appeared on error meters watched by the person talking to the plane, whom we called the Controller. Here's a needle that goes up and down, and here's a needle that goes right and left. Let's say you're 50 feet too far to the left or the right, up or down, he would call out the corrections.
Nebeker:
That's fascinating to hear about those cams. Of course, these days everything would be done electronically.
Johnston:
And with a database, yes. But it was a very down-to-earth system. Anybody could look at it and see how it worked. That original 584 was very much in demand and we didn't get to use it all until much later, finally we were given it for a week to try landing planes. Up until that point, we had done a lot of experimental work just using an optical theodolite to get azimuth and elevation angles on a plane as it came in, and simple radar for range. So we built a system on that, assuming that we would eventually get the same coordinate information from the gunlaying system. It was a terrible shock when we finally got our hands on the gunlaying system to find that if you aimed it close to the ground, it went crazy.
Nebeker:
Too much reflection?
Johnston:
Yes, there was too much reflection from ground objects. And reflection from the ground plane. So there was a virtual image of the plane underground. The poor servo system, the thing would bob the dish up and down and go crazy. It was a terrible shock when we realized that this radar system wasn't going to work for us.
Radar Innovation
Nebeker:
Do you remember roughly when that was?
Johnston:
That must have been early in '42 that we finally got our hands on the 584 radar. Alvarez was always ready, though. He had already dreamed up a special kind of an antenna with a very narrow beam angle that was used with Eagle and with MEW that would not cast radiation on the ground. So within a couple of days he had talked to Alfred Loomis, whom he always went to when he needed encouragement. They laid plans then and there to build these special antennas and a whole new radar system to go with them.
Nebeker:
That, of course, changed just about everything that you'd done up to that point.
Johnston:
Yes. We had to start from zero. But these antennas were a spectacular success, a brand-new idea of making a linear dipole array feeding a cylindrical paraboloid. A long waveguide was used to feed these dipoles every half wavelength along it.
Nebeker:
You were project engineer for all of that?
Johnston:
Yes.
Nebeker:
How did it all go?
Johnston:
It went fabulously well. Here's this big tall narrow antenna about 12 feet high, and it had a tremendous moment of inertia, and the thing was rocking up and down for elevation information. If you looked at the scope that it was connected to, you could see the reflections, under the ground plane but you knew they were a reflection. You knew the plane wasn't under the ground there. So here's a plane above the ground and one below the ground. [Chuckling] But there was no temptation to confuse the two. So the problem was really solved that way.
Testing Ground Controlled Approach (GCA) System
Nebeker:
So you got to the stage where you had the whole system put together. How did the testing go?
Johnston:
We took the Mark I GCA to various Naval Air stations on the Atlantic Coast for tests. The Navy was very helpful to us in supplying test planes and pilots, and of course those pilots wanted to use Navy landing fields familiar to them. The Air Force showed very little interest in our project.
Nebeker:
Was it mainly Alvarez who would be talking to the military leaders to try to get their interest in blind landing?
Johnston:
I think so. I didn't operate at that level. But Luis was very much at home talking to important people. The Lab, of course, had military liaison people who would have been his natural starting point. It helped immensely, of course, that Luis was an enthusiastic flyer of small planes. Whenever he got hold of someone who was a flyer, they had instant rapport.
Nebeker:
What Naval Air Station did you use?
Johnston:
Quonset Point Naval Air Station was where we did most of our work. We started out at Logan Airport in East Boston. But the security wasn't very convenient there, and our Navy pilots were much more at home at their naval bases.
Nebeker:
Were they sold on it after the initial tests?
Johnston:
The aviators themselves were very much sold on it, and they probably talked to their superiors. But I don't think that the proposition to sell them one was put to them until a subsequent big set of tests. We had some very exciting experiences. At Quonset Point we were in a heavy snowstorm working with the radar set out on the airfield doing routine maintenance on it. We had a phone to the control tower and the commander called. He must have known what we were up to, because he said, "We have a flight of PBYs that are lost and low on fuel. Can you guys find them and bring them down?" So we talked to them and brought them down.
Nebeker:
That system didn't require any special apparatus in the airplane.
Johnston:
That was the genius of this system, I think.
Nebeker:
And those people hadn't been trained?
Johnston:
They did not even know about radar. It was the best example of faith that I have ever seen. We vectored them around for a while. We had a search system that went around 360o, and in addition to this our precision system that covered the glide path region. Luis Alvarez talked to them and said, "We have a system where we can see where you are."
Nebeker:
Alvarez himself?
Johnston:
Alvarez himself did most of the controlling whenever he was available. He loved to do it.
Nebeker:
Did you do that as well?
Johnston:
Only a few times. I was usually running other parts of the system.
Nebeker:
That must have been a rather tense time for all. I mean, you'd done a lot of tests with it before, but these were people who'd had no experience with it.
Johnston:
Yes, this was for keeps. Luis was a very convincing sort of a person. He said, "We can see you." So he vectored them around for a while, and he criticized their flying: "You lost 50 feet in that turn." [Laughter] I'm not sure whether he actually saw that or assumed that they were, because he was an amateur flyer himself.
Nebeker:
He gained their confidence and then brought them in.
Johnston:
Yes. There were three PBYs. He talked to the leading one, and the other two followed him right down the runway. They landed one right after another, a couple hundred feet apart on the runway.
Nebeker:
It says that you stayed at the Rad Lab until May of '43.
Johnston:
Yes.
Nebeker:
Does that sound right?
Johnston:
Yes, that's when I left for Los Alamos. They don't indicate there that I left the Lab and where I went. There was some bitterness about my leaving.
Nebeker:
Was that the time that Alvarez was moving to Los Alamos? Or had he already gone out there?
Johnston:
I left shortly after he left. Maybe we should finish up about GCA while we're at it. Because the climax was that after we were pretty confident that we knew what we were doing, they arranged for a major test at the National Airport in Washington. There must have been a number of people that were convinced that this was something worthwhile. So they brought in big admirals and generals. To see how it worked.
Nebeker:
I'm recalling what Alvarez wrote in his book about these tests now. There were repeated failures. I'm sure you were doing all you could to get things going again?
Johnston:
Yes. But I felt personally responsible for one of the major things. Our big power tubes that drove the magnetrons were failing on us. The bumpy ride from Boston to Washington had weakened the filaments.
Nebeker:
Do you think that was what it was?
Johnston:
I think there's no doubt about it. We got there several days before the test, and we had a number of spares. They kept using up these spares. I could have made a call to the Lab and said, put some of those 304 TLs on a plane and send it down here. But I was optimistic that we had some good tubes left there. That was a hair-breadth thing, that we finally got it going in time.
Nebeker:
I'd forgotten that account of his.
Johnston:
He was briefing these boffins, that's the British word that they used for big shots.
Nebeker:
What is the name?
Johnston:
Boffins. He picked up quite a few British slang expressions from Taffy Bowen. He expected to give the boffins about a half hour's briefing and then say, Let's go on out to see the system. But he had to keep it up for a couple of hours until I came in and told him that things were running. The generals and admirals just had a field day. They were all flying people. They insisted on flying the tests themselves, and they made repeated landing runs. Alvarez was controlling, and he criticized them freely on their flying techniques. [Laughter] Some of them were fairly rusty, I guess. They were really sold. We set up the loudspeakers for the communication outside the radar truck, and the guys that were waiting to try their hand at flying a plane were listening to this. They were impressed with the feedback they got back from the general who was flying the plane.
Nebeker:
That was a good idea! They could hear both sides of the conversation.
Johnston:
Yes. Alvarez had great instincts for PR, in a day when it wasn't emphasized as much as it is today.
Nebeker:
Was that the major selling that that got?
Johnston:
It was the selling of the GCA. We had a dozen sets on order then, and they all wanted them, and we could have sold 50 of them right there.
Nebeker:
These dozen sets, were they produced at Rad Lab?
Producing GCA
Johnston:
Those were produced by the Gilfillan Radio Company that I mentioned. Luis Alvarez's memoirs would probably tell you about Gilfillan Radio. It was a small radio manufacturing outfit in Los Angeles that made household radio receivers.
Nebeker:
What did you on that GCA project do at that point? Did you then need to get into large-scale production?
Johnston:
This initial production of twelve was enough, we felt, to make a large-scale test of it. There was a transition office. Roland Gaither, I think, was in charge of that. There were so many high-class people that were used to handling millions of bucks, such as Alfred Loomis. These were people that thought big and foresaw things. They got a contract with Gilfillan Radio for the twelve as soon as our plans for the Mark II GCA were set. In Mark II GCA we used Alvarez's electrical scanning antennas, so the whole antenna system didn't have to move. They just squeezed the waveguide, and that made the beam sweep back and forth. There was a brand new system of oscilloscopes that made a display that you could interpret easily. They brought several engineers from Gilfillan Radio right into the Rad Lab. They worked right with us in developing the equipment, and they made lists of materials and diagrams. By the time we had Mark I working, they had the complete specs documented. They had orders in for all the electronic components, and they kept changing their orders as we kept changing our minds.
Homer Tasker was the principal person that lived with us at the Rad Lab. He was a very high-flying person. He took part in the discussions of how it should work and contributed some ideas to it. After the war there was a patent argument. He thought maybe he had invented the ideas of Mark II GCA. We took out the patents in the name of myself and of Chalmers Sherwin, who developed the indicators and the scopes for it. They were all ready to go into production on Mark II as soon as we ran through those tests on Mark I. Then my job was to go to Gilfillan in Los Angeles and help them with production problems.
Nebeker:
It wasn't that changes were made in design, but just the actual manufacture of it?
Johnston:
Yes. To make something producible in larger quantities, they had to repackage things to some degree. But they checked all those changes out with me or the expert on a particular electronic box. At that time I went to Gilfillan to help them get it into manufacture, and Luis and the rest of the crew went to England to get the Mark I GCA into the Battle of Britain. They did a fair amount of landing of planes in Britain under battle conditions. They kept sending back certain suggestions about how the thing might be modified, and some we adopted. Others we said, that'll be Mark III, I guess.
Nebeker:
Such communications, how did they take place? If you heard from Alvarez in England.
Johnston:
They were just personal letters.
Nebeker:
Letters. Not encoded or anything?
Johnston:
No. In those days we sent registered letters, anything that was secure. We'd seal it in several envelopes and register it. I didn't know why that was supposed to be a lot more secure, [Chuckling] but that's the way things were done.
Nebeker:
Is there anything more you'd like to say about GCA?
Johnston:
No, I don't think so. It's well known that it worked pretty well in wartime, and it did an essential job during the Berlin Airlift. They managed to keep the planes flying in bad weather into Berlin using GCA.
Nebeker:
What was your own involvement in it after this period at Gilfillan?
Johnston:
After the war I was involved in a few tests of it, and I was a paid consultant with the Gilfillan Company while I continued my graduate work in California.
Los Alamos
Controversy at Rad Lab
Nebeker:
Does that take us up to the move to Los Alamos?
Johnston:
Yes. The transfer to Los Alamos was a bit traumatic because Alvarez just assumed that everybody at MIT would see that the Los Alamos project was a lot more important at that time. He told me, "Talk to Wheeler Loomis, the Rad Lab personnel director, and if he doesn't want to let you go, talk to Conant at Harvard." He just left me on my own to do that. So I went to Wheeler Loomis and said, "Well, I think it's time to go. Luis wants me to come to Los Alamos, and this is what I want to do." Wheeler Loomis was very cool, but he said, "Are you sure you want to do this? You've been doing great things for us, and we want you to go to the British Liaison Office and help get GCA going over there. We have all sorts of good things in line for you here." "No," I said, "I really want to go." He said, "I think you should talk to Rabi." So I made an appointment with Rabi. He was the technical director, I guess. Rabi said, "No, I don't want you to go. We need you here. If everybody who got a whim to go somewhere else went, we couldn't manage things very well. You can't run a war that way." Then I made an appointment with Conant and talked to him. He said, "What's the problem?" I said, "I feel that I ought to go to Los Alamos, and they don't want to let me go. I guess you know what's going on at Los Alamos. Luis Alvarez wants me to go there." And Conant said, "Have you finished up your stuff here?" "Yes," I said. So he said, "I think you ought to go to Los Alamos." He said, "Go talk to Wheeler Loomis again." [Laughter]
Nebeker:
He didn't offer himself to say a word for you?
Johnston:
No. I was very impressed with Conant. He seemed to just completely forget everything else that must have been on his mind. He seemed to be completely thinking about your problem. Not many people seem to do that.
Nebeker:
So you went back to Loomis?
Johnston:
Yes.
Nebeker:
How did that conversation go?
Johnston:
He said, "Well, you can go." [Chuckling]
Nebeker:
I see. Why did Conant's opinion carry so much weight?
Johnston:
I don't really know.
Nebeker:
Maybe you made clear that you very much wanted to go by pursuing it that far. That you didn't take Rabi's response as final.
Johnston:
Maybe. I don't know what wheels were working, but I suspect that Alvarez had primed people. Conant, I think, was high up on committees, where they handled such disputes.
Nebeker:
Did you feel at the time that Alvarez should have intervened?
Johnston:
I was thinking that he should. As far as I was concerned, maybe he should have made all the arrangements for me to go. I'm glad now that I went through this process.
Nebeker:
Were there others working with Alvarez there who made the move at the same time?
Johnston:
Not that were working with Alvarez. But there were quite a few others who went.
Nebeker:
I know there were a lot who went to Los Alamos. Were there hard feelings with the people you'd been working with on GCA that you were leaving?
Johnston:
No, not at all. The other people that I was working with understood perfectly well. I don't think they knew what I was going to be working on. No, there were no problems whatsoever there. These guys were all Luis' cronies and had grown up with Luis. George Comstock was happy, I think, that he would step into the position of project engineer. He got along very well with everybody and was more of a people-person than I was. I was much younger and more of an equipment-type person.
Nebeker:
I know that Alvarez made a number of trips back to Rad Lab and continued to some extent to be involved with Rad Lab after that. Is that right?
Johnston:
I was not aware of that.
Nebeker:
I'd been told that.
Johnston:
He may easily have. He was always on the move.
Nebeker:
But for you it ended all your Rad Lab work?
Johnston:
Yes, it was cut off cleanly.
Comparison of Rad Lab and Los Alamos
Nebeker:
One thing we're very interested in is a comparison of Rad Lab with Los Alamos. How did those two places compare in your experience?
Johnston:
They were very similar in the esprit de corps. Both of them had a tremendous sense of purpose and a feeling that anything you needed you could get. There was a very high priority in getting equipment. I was much more aware at Los Alamos of famous physicists around. Fermi was there and Niels Bohr, people that I had heard of all my life. So that was different. In retrospect, more of the Rad Lab people who became famous later were younger. Such Ramsey, Purcell, McMillan, and Alvarez. Of course, being out in the wilderness at Los Alamos was different. It was a high desert wilderness and I love camping and outdoor stuff, so that was a great change as far as I was concerned.
Nebeker:
And a change for the better from the Boston area?
Johnston:
Yes. I was happy either place. But I've learned any place that I am to do the things that can be done well there. But I love to hike, and we were starting a family by then. That was a big plus for Los Alamos. Previously it was an advantage that I could go to Gilfillan, since my wife was going to have a baby. My parents home being in Los Angeles, it just seemed a natural to choose to go there instead of to England while my baby was being born and while the GCA system was getting into production.
Nebeker:
I see. How long were you at Gilfillan?
Johnston:
I was there for about nine months, I believe.
Nebeker:
I see. I'm curious. I've been told by some people that even their wives didn't know what they were doing at Rad Lab.
Johnston:
Mine had something of an idea. During a long series of tests at Naval air stations, since we were newlyweds at that time, Luis Alvarez suggested that she could come along with us. So she was living with that crew of about ten people, and we'd eat in restaurants together. She heard an awful lot of chitchat. [Laughter] She got a pretty good idea there.
Nebeker:
But was it a matter of security considerations that as a rule you just didn't discuss work at home?
Johnston:
Very much so.
Nebeker:
It was the security consideration rather than not wanting to think about work at home?
Johnston:
Yes, it was security.
Nebeker:
Were you working under Luis Alvarez at Los Alamos?
Johnston:
Yes. We both wanted it that way.
Nebeker:
And you didn't see any great differences in style of work there as opposed to Rad Lab?
Johnston:
The stakes seemed a bit larger because of the bomb that was being produced. There was a bit more of a sober feeling, I think, that we were doing something that was unprecedented. In both cases it was unprecedented, but the stakes seemed to be higher at Los Alamos.
Nebeker:
How was that reflected in day-to-day activities? Did people work longer hours?
Johnston:
Management decisions were the biggest thing that I noticed. At both places we worked very long hours. If a crisis was coming up, we'd work as long as we needed to, to get past the crisis. But management at Los Alamos seemed to make big decisions, and we'd change the course of things in quite a hurry.
Nebeker:
I've heard from many people that at Rad Lab there was a fair measure of self-direction. That if someone thought this was the avenue to pursue, he could do it. Maybe there was less of that at Los Alamos?
Johnston:
I think that is probably true. At Rad Lab you were free to dream. If you could dream of another use for the system or another system that was similar, you could go ahead and do it. If it required money and facilities and people, then you talked to the steering committee to get the logistics handled. But nobody asked you "Are you sure that's being used for GCA?" or anything like that.
Nebeker:
And at Los Alamos the individual tasks were better defined by upper management?
Johnston:
I think so. It was handled through channels. There were several layers of administration. But there wasn't the breadth of possibilities there that there was at the Rad Lab.
Nebeker:
What about relations with the military? You mentioned with GCA, the Navy. What other relations did you have with the military?
Johnston:
Not very much. At the working level, we lived with these aviators.
Nebeker:
What about your time at Gilfillan? Were there military engineers there seeing that their specifications were advanced?
Johnston:
No, I was supposed to be representing the military. I approved any significant changes in equipment. For the final acceptance tests, the sets were called AN/MPN-1 (that was the military designation for the GCA sets that were produced). I got the full crew (they were back from England by then) to come out and run the set. We tested the antenna patterns, the display calibrations and everything that we felt needed to be done.
Work on Detonators
Nebeker:
At Los Alamos did you have any dealings with the military directly?
Johnston:
Yes. There were quite a few military technical people in uniform there; a fair number of our explosives experts there were military. But the military command was maintained through Oppenheimer; George Kistiakowsky, a chemist from Harvard, was in charge of the explosives division; and Alvarez was his right-hand troubleshooter. He sat in Kistiakowsky's office all the time, kept his ears open for developments, and came up with suggestions. So like at the Rad Lab, he came up with some projects of his own. One project was a method for testing the implosion method of assembly of the "Fat Man." It was a terrible problem at Los Alamos, how to get a spherically uniform implosion. Because if it wasn't uniform, the plutonium would just squirt out at any low-pressure place. He had a project of his own, with several people working with him, to make a particular way of testing for uniform implosion. The project I worked on was the detonators for the high explosive shell. In order to get a uniform implosion, you needed to start it detonating in a large number of places with a very high degree of simultaneity. That was my project, and I hold the patents on that type of detonator known as the exploding bridgewire detonator.
Impact of Rad Lab on Career
Nebeker:
A question we ask everyone and would like to ask you is, how you would describe the effect of your Rad Lab years on your subsequent career? What difference it made to your subsequent career?
Johnston:
I think it helped me to think big in terms of projects. I've worked on several accelerator projects since the war.
Postwar
Proton Linear Accelerator
Nebeker:
So you went back to graduate school after the war?
Johnston:
I went back to graduate school at Berkeley in 1945.
Nebeker:
In nuclear physics?
Johnston:
In nuclear physics. The job that I got for support was helping Luis Alvarez build a new type of proton linear accelerator, which has become a well-known device. It's now used as an injector for large circular accelerators. Then my first job was to go to the University of Minnesota and build a larger version of that proton linear accelerator.
Nebeker:
All of your electronics work put you in good stead there.
Johnston:
High-powered electronics was just made for accelerators as well as for radar. It certainly had an influence on my career. On a slightly different subject, my employment since graduate school has been mostly in academic physics departments. It is interesting to look back to see the reactions of some of my academic colleagues to my involvement in wartime weapons research.
Academic Bias Against Military
Johnston:
In academia I found many who had a strong antipathy to the military, against our having developed the A bomb, and our having used it against Japan. Some of these, I think, would have felt better if we had lost the war or if there had been a prolonged bloody stalemate. I didn't hear very much reaction against radar, probably, because it was finding valuable uses in civil aviation. It is getting difficult to remember now, since the collapse of the Soviet Union, the degree to which many leaders in academia, including physicists, were sympathetic to the "great egalitarian social experiment" of Lenin and Stalin. I found myself labeled a "Red Baiter" or a "Fascist" if I mentioned the totalitarian nature of the Soviet system of government, or Stalin's murder by starvation of the millions of Kulaks in the Ukraine. I hope that historians will try to explain why so many of our intellectual leaders in the five middle decades of the 20th century were so tolerant of oppressive totalitarian Socialist regimes in the USSR, Cuba and China, while courageously leading the crusade against Fascist totalitarian regimes in Germany and Italy during the war and after. I find this selective moral blindness to be a serious failure of our intellectual elite, in which I include myself. The thing that I think gave me more perspective than many of my peers was a Christian worldview, which includes the idea that there is a transcendent someone who cares about truth and who cares about how we treat our fellow creatures.
Further Thoughts on Rad Lab
Nebeker:
What about personal connections made at Rad Lab? Did that make much difference to you afterwards, the contacts?
Johnston:
Yes, some of our life-long friends have been people in Rad Lab. Particularly a guy named Chalmers Sherwin, who helped with the indicators. He developed a lot of the indicator ideas that we built into the Mark II GCA. In fact the patents on Mark II GCA are taken in the names of myself, Alvarez, and Sherwin.
Nebeker:
What about your professional career? So many people seem to owe later positions to personal acquaintances made during Rad Lab days.
Johnston:
My first academic job was at the University of Minnesota, and that was entirely because of my work with Alvarez. The people at Minnesota wanted to build a larger version of Alvarez's proton linear accelerator, and wanted one of Luis's people to head up the project. So he chose me for the job. In those days, the Atomic Energy Commission was willing to fund almost any modest-sized accelerator project, if it was recommended by Ernest Lawrence or Luis Alvarez.
Nebeker:
Anything else about Rad Lab you'd care to comment on?
Johnston:
One of the big things that I noticed, when I went back later in the war, was that the place, the whole atmosphere, had changed. This was about mid-1944.
Nebeker:
Oh?
Johnston:
The whole atmosphere had changed into empire-building, and "what's in it for me."
Nebeker:
That's very interesting.
Johnston:
The whole idea of selfless devotion to what you were doing seemed to have disappeared.
Nebeker:
Is that right!
Johnston:
This is the way I experienced it.
Nebeker:
And a lot more politicking that you hadn't experienced in your time?
Johnston:
That's right. Of course, I was not in the upper echelons where the real politicking went on. But everybody was talking. The symptom was that you'd see people off in a corner, half a dozen people, talking about something and not too anxious to be overheard.
Nebeker:
Are there other explanations that you can think of for that change in atmosphere at Rad Lab?
Johnston:
Maybe it was just the natural development from success. The Lab's objectives were all met. It was just to carry on with the contracts that had been let. Most of the places I've been ever since, this politicking has been part of the process, even at universities.
Nebeker:
So that in a period of rapid growth and newness of activity, there might be less of that?
Johnston:
It was the difference between night and day. The early experiences, you just were riveted on the life-and-death issues that were there. Can the Nazis be stopped?
Nebeker:
What about at Los Alamos? Was it relatively free of the politicking?
Johnston:
Yes. I wasn't aware of it. But the same thing happened when I got back to Los Alamos after the war. It was just another government lab. [Chuckling]
Nuclear Bomb Controversy
Nebeker:
That's interesting. You don't have any regrets about having made the move to Los Alamos when you did?
Johnston:
No, I don't. I've been asked many times whether I regretted doing work on the A bomb. At the fortieth anniversary of the Hiroshima bomb, a writer from Newsweek came to interview me at my laboratory. This was to be part of a big article (Newsweek, July 29, 1985) covering the event. We went through the story step-by-step, of my going to Los Alamos, of being assigned the job of inventing the kind of detonators required for the "Fat Man," of flying with the bombing mission, and finally taking out the patents on the "exploding Bridgewire" detonator. At least five times during this interview, he asked me, " by this time weren't you starting to feel guilty about what you were doing?" And my answer, more or less, was that I felt very privileged to be part of an effort that promised to end the war abruptly, and which had the prospect of saving many lives, both Japanese and American.
Nebeker:
I wasn't thinking of it in those terms. I've heard so many good things this week about Rad Lab.
Johnston:
Yes, Rad Lab was a wonderful place. In many ways it was more pleasant at Rad Lab working with blind landing of airplanes, which was made to save friendly aircrews. But in each case, I felt glad to be a part of getting the war successfully terminated, and returning the world to sensible pursuits. This included, of course, my being able to get back to finishing my graduate studies in physics.
