I was saddened today to hear of the death of David Cline. I do not have much to say here - I am not good with obituaries - but I do remember meeting him at a conference in Albuquerque in 2008, where we chatted on several topics, among them the history of the CDF experiment, a topic on which I had just started to write a book. 

Perhaps the best I can do here as a way to remember Cline, whose contributions to particle physics can and will certainly be better described by many others (for example,
http://www.pa.ucla.edu/content/david-b-cline ), is to report a quote from a chapter of the book, which describes a funny episode on the very early days of CDF. I think he did have a sense of humor, so he might not dislike it if I do.


In 1984, with the main detector components already in a phase of advanced construction, the physicists who had designed the experiment decided to put the details of the project in print; they had already produced a typewritten design report in 1981 as a document mainly intended for internal consumption within the laboratory, but now the time was right to have a complete and up-to-date document published by a scientific journal. The publication of a "Technical Design Report" (TDR) is a common practice in particle physics experiments, where the hardware is usually way too complex for a meaningful description in every physics article describing data analysis, especially due to the space limitations of most scientific magazines. In a TDR the various detector components can be described in full, and their specifications spelt out in detail. 

The editing of the CDF TDR was done by Henry Frisch and Hans Jensen. They described each of the main components of the detector in different chapters of the long paper;  of course they also inserted a description of the potential of the detector to study the various physics signatures of interest; in one chapter they addressed the capabilities of the hardware for "forward physics," with a description of the detector elements that could study particles emitted at small angle from the beams direction, and their expected performance. Forward physics deals with processes involving a low centre-of-mass energy of the hard subprocess, and is therefore a topic of secondary interest for hadron collisions, whose main purpose is the study of high-energy phenomena, ones giving rise to particles emitted at large angles with respect to the beam direction, which are intercepted and measured accurately by the central detector systems. 

    Once Henry and Hans were done drafting a first version of the article, they arranged the draft to be distributed to all the collaborators. On the following day Henry received a phone call from David Cline. Cline had formerly written an important article on forward physics, and he was not happy since his work was not being mentioned. 

    "I invented forward physics, so I want to be referenced early in the text of our TDR," he said.

 Henry was taken aback: "But Dave, look, it's not a question of recognizing your contribution - you are an author of the TDR anyway!"  I should maybe explain here that the practice of self-citation in one's articles is not despicable per se, but just maybe not very elegant if the citation is not strictly meant to benefit the reader. The latter was not the case of the TDR, whose focus was the CDF hardware rather than the phenomenology of physics processes. Yet Cline insisted. 

"I don't care. Forward physics is my idea, and I want to be referenced. Please add a reference to my paper, as early in the text as possible." There was no arguing with Cline: Henry had to promise that he would. A few days later, once all the requested modifications were made and the text was declared ready to be sent to Nuclear Instruments and Methods, he walked up to the secretary who had been physically editing the text in the computer. 

"You have to do me a favor," he said.  "I have to make a small change to the TDR, but this one might cause trouble, so please do not tell anybody, including Roy." Roy was Roy Schwitters, who led the CDF experiment with Tollestrup at the time. The secretary agreed, and Frisch proceeded with his instructions: 

    "The one change to make is to put a reference after the name of David Cline, just when it is listed in the author list, below the abstract. This is of course going to be reference 1 of the article. In the list of references you should correspondingly input the following text: 'David Cline wanted to be referenced early.' Just that." 

The secretary complied to Henry's request, and the article was sent to NIM with the sarcastic joke. It is too bad that the NIM editors were able to spot the odd reference and deleted it before printing their magazine.