Walter Koski was employed by the Atomic Energy Commission as a physical chemist with special expertise inthe area of high-explosive lenses. He worked at Los Alamos for three years beginning in 1944. Koski was called as a witness to explain the significance of the lens mold sketches that David Greenglass said he gave to Julius Rosenberg in January 1945.

SAYPOL: What did your work involve?

KOSKI: My work was associated with implosion research connected with the atomic bomb.

SAYPOL: So that we, as laymen, may understand when you say implosion research, does that have something to do with explosives?

KOSKI: The distinction between explosion and implosion is in an explosion the shock waves, the detonation wave, the high pressure region is continually going out and dissipating itself. In an implosion the waves are converging and the energy is concentrating itself.

SAYPOL:I take it, concentrating itself toward a common center?

KOSKI: Toward a common center.

SAYPOL:In other words, in explosion it blows out; in implosion it blows in?


SAYPOL: Is implosion one of the physical reactions incident to the overall action in the atomic bomb?

KOSKI: It is.

SAYPOL: So, as I understand you, your precise job was to make experimental studies relating to this phenomenon of implosion?

KOSKI: It was.

SAYPOL: Mr. Koski, in the performance of that work, did you have occasion to use what has been called here a lens, a device called a lens ?

KOSKI: I did.

SAYPOL: What is the lens as you knew it in connection with your experiments?

KOSKI: A high explosive lens is a combination of explosives having different velocities and having the appropriate shape so when detonated at a particular point, it will produce a converging detonation wave.

SAYPOL: Well, once again, so that we as laymen might understand, I take it our common conception of a lens is a piece of glass used to focus light, is that right?

KOSKI: Yes, that is right.

SAYPOL: What is the distinction between a glass lens and the type of lens you were working on?

KOSKI: Well, a glass lens essentially focuses light. An explosive lens focuses a detonation wave or a high pressure force coming in.

(Koski described his work in developing high explosive lens mold. He was then shown the lens mold sketches drawn by Greenglass.)

SAYPOL: Would you recognize it as a reasonably accurate replica of the one you submitted to the Theta machine shop?


E. H. BLOCH: Now, if the Court please, I have no objection to the substance of this question, but I ask that the time be more definitely fixed.

COURT You do remember that they were some time during the years 1944 and 1945?

KOSKI: They were.

(Koski was asked if any other nation was conducting similar experiments at the same time.)

KOSKI: To the best of my knowledge and all of my colleagues who were involved in this field, there was no information in textbooks or technical journals on this particular subject.

SAYPOL: In other words, you were engaged in a new and original field?

KOSKI: Correct.

SAYPOL: And up to that point and continuing right up until this trial, has the information relating to the lens mold and the lens and the experimentation to which you have testified continued to be secret information?

KOSKI: It still is.

SAYPOL: Except as divulged at this trial?

KOSKI: Correct.

COURT As far as you know, only for the purpose of this trial?

KOSKI: Correct.

SAYPOL: Will your Honor allow a statement for the record in that respect? The Atomic Energy Committee has declassified this information under the Atomic Energy Act and has made the ruling as authorized by Congress that subsequent to the trial it is to be reclassified.

COURT: Counsel doesn't take issue with the statement?

BLOCH: No, not at all. I read about it in the newspapers before Mr. Saypol stated it.


BLOCH: Dr. Koski, did you turn over any of the sketches re- quested in Government's Exhibits 2, 6 and 7 to the defendant Greenglass?

KOSKI: I did not.

COURT: Was the defendant Greenglass in a position whereby reason of his employment in the Theta shop he could see the sketches which you turned over?

KOSKI: He was.

(Bloch then asked about the two exhibits which were sketches of the mold.)

KOSKI: This is a rough sketch and, of course, is not quantitative but it does illustrate the important principle involved.

E. H. BLOCH: It does omit, however, the dimensions?

KOSKI: It does omit dimensions.

E. H. BLOCH: It omits, for instance, the diameter, does it not?

KOSKI: Correct.

COURT: You say it does, however, set forth the important principle involved, is that correct?

KOSKI: Correct.

COURT Can you tell us what that principle is?

KOSKI: The principle is the use of a combination of high explosives of appropriate shape to produce a symmetrical converging detonation wave.

E. H. BLOCH: Now, weren't the dimensions of these lens molds very vital or at least very important with respect to their utility in terms of success in your experiments?

KOSKI: The physical over-all dimensions that you mention are not important. It is the relative dimensions that are.

E. H. BLOCH: Now the relative dimensions are not disclosed, are they, by these exhibits?

KOSKI: They are not.

E. H. BLOCH: That is all.

Redirect examination

SAYPOL: The important factor from the experimental point of view is the design, is it not?

KOSKI: Correct.

SAYPOL: That was original, novel at the time, was it not?

KOSKI: It was.

SAYPOL: Can you tell us, Doctor, whether a scientific expert in the field you were engaged in could glean enough information from the exhibits in evidence so as to learn the nature of the object of the experiment that was involved in the sketches in evidence?

KOSKI: From these sketches and from Mr. Greenglass' descriptions, this gives one sufficient information, one who is familiar with the field, to indicate what the principle and the idea is here.

SAYPOL: Would I be exaggerating if I were to say colloquially that one expert, interested in finding out what was going on at Los Alamos, could get enough from those exhibits in evidence which you have before you to reveal what was going on at Los Alamos?

KOSKI: One could.