The text below is the fourth part of what could have become "Chapter 13" of the book "Anomaly! Collider Physics and the Quest for New Phenomena at Fermilab", which I published in 2016. For part 1 see here; for part 2 see here; for part 3 see here.

A written proposal to admit senior member Paolo Giromini to CDF II was sent by the head of the CDF-Frascati group Marco Cordelli to the spokespersons Ristori and Lockyer on January 27th, 2004. The recipients duly informed the Executive Board representatives of the institutions participating to the experiment, suggesting that the matter be discussed at the upcoming board meeting in March. A flurry of emails immediately started to pester the restricted mailing list of board members. The messages pictured well the reaction with which the message had been greeted by some of the institutions participating to the CDF experiment: a mix of disbelief, frustration, rage, and determination to reject the offer. Of course those messages did not reflect the opinion of the majority of the collaborators. Notwithstanding, as was often the case in CDF, a vocal but determined minority could easily get the upper hand. In his long battle to publish his analyses Paolo had managed to jeopardize his relations with many American members of the experiment, and had cut ties even with others who had initially liked his uncompromising, frank way of interacting with collaborators, based on valuing more physics truth than good manners. To some of the CDF II arch-enemies of Giromini, the proposal felt like an attempt to game the system by twisting the collaboration rules, little short than plain rape.

Henry Frisch, Lina Galtieri, Tony Liss, Brig Williams, Larry Nodulman, and many other old timers initially thought that a fail-proof argument could be erected to rebut Paolo's joining proposal. CDF rules were extremely clear on the issue of membership: he had not participated in the construction of the new detector, and had not contributed to the success of the upgrade by performing the mandatory 9-day-shifts of cable pulling or board soldering, nor other low-level tasks which had been requested to all members between 1998 and 2001 to supplement the scarce personpower available for the detector upgrade in a period of shortage of technicians. On the contrary, they could make the point that Giromini had always argued in public that the investment of time and efforts in Run 2 was foolish, and that the project was too complex and deemed to fail. They felt he was a persona non grata; from their perspective, with all the pains he had caused to CDF in Run 1, there was in their opinion ample ground to reject his request. In short, Paolo did not qualify, and he was utterly unwelcome by some of his historical opposers, many of which had reached influential positions in the collaboration. Despite a mediation attempt of the patriarch of the Italian group in CDF, Giorgio Bellettini, on April 29th 2004 an Executive Board meeting vote turned down Giromini's request of admission to CDF II. According to the CDF bylaws, this was enough to settle the matter; however, it soon transpired that internal rules alone were not enough.

The INFN president until June 2004 was Enzo Iarocci. A highly esteemed physicist who had given ground-breaking contributions to the design of new wire detectors (the so-called "Iarocci tubes") thirty years earlier, Iarocci held Paolo Giromini in high esteem as a scientist. Upon hearing from Paolo news of the impasse, he stepped in by sending an official letter to Luciano Ristori and Young-Kee Kim (the latter had just replaced Nigel Lockyer as co-spokesperson), and in copy to the Lab director Mike Witherell. In the letter, dated June 9th, Iarocci explained that it was not really possible for CDF II to decide to keep an INFN researcher from joining the collaboration. The Italian institution participated to CDF II with funding, technical support, and human resources, and the decision rested in its hands. The vote cast by the CDF Executive Board was therefore to be considered inconsequential.

The CDF spokespersons brought the letter to an open session of the following Executive Board meeting, when Luciano read it in front of the audience packed in the CDF Theater. The reaction of the collaborators was almost unanimously negative: it looked impossible to accept what appeared as an external diktat. Yet Iarocci's letter could not be dismissed. The experiment lived by the hard work and collaborative effort of scientists from fifty universities and research institutes around the globe; further, it could never had come into existence without the financial support of the funding agencies that provided support to those institutions. The Italian institution had contributed quite significantly from the very start, and it had the right to exploit its investment.

The spokespersons spent the following few weeks trying to persuade the sternest opposers, asking them under what circumstances they would accept the membership of Giromini. Some of them said that if he were to threaten again the collaboration to publish unapproved material he was to be kicked out with no mercy; others requested Iarocci to be an explicit warrantor of the future conduct of Paolo; a small hard core group rejected any compromise. Negotiations went on for a significant amount of time, but they did not converge.

The matter under discussion had also practical implications: what would Giromini's role and contribution to Run 2 be? In principle, it could be anything: in the past Paolo's experience and competence had been a great asset to the experiment; he had solved many challenging detector problems with his initiative and insight. His main contribution to CDF, identified as an institutional responsibility of the Frascati group, had been the design and construction of the central hadron calorimeter, which had entailed the adoption of brilliant innovations for, e.g., the design of a comb-like structure of light guides which collected the light produced in all the scintillator planes, feeding it into the photomultiplier tubes. But his contributions to CDF did not stop there. For instance, he had invented a solution to a nagging problem in the detection of muons in the CMX system, which once installed had been observed to receive unforeseen large backgrounds. Those backgrounds arose when proton remnants exiting the collision point hit the walls of the forward calorimeters, bouncing off them and traveling unhindered to the muon system, from an angle which bypassed the thick material of the central detector. The background could be removed by offline analysis, but its presence prevented the triggering on CMX signals, because the accept rate from that detector would be too high; unable to record events which contained CMX muon signals, CDF would effectively be "dead" to those events. The simple and elegant solution that Giromini invented was to create a cunning electronic "mean-timing" system. The system measured on the fly the crossing time of particles hitting the CMX, by converting into integrated electric charge the time difference between the signals received by the photomultiplier tubes reading light at the two ends of the long scintillator planes that complemented the gas chambers. This allowed the CMX readout to only trigger on particles detected in synchrony with the proton-antiproton collisions, once the travel time from the center of the detector to the chambers was factored out: the nasty background was effectively killed. Also, the Italian scientist had studied those backgrounds in detail with the help of a careful Monte Carlo simulation, finding that they were at least in part due to the presence of a thick iron beam pipe and flange connected to the central tract of beam pipe (which was instead duly made of Beryllium, a light material that would minimally interfere with the trajectory of particles created in the central collisions). He had then designed and installed a custom corrugated steel beam pipe which had helped to further reduce those backgrounds. In short, the CDF muon system triggered happily and effectively only thanks to his inventions.

One idea for a Run 2 contribution of Giromini was connected to an old promise he had made to his SVT colleagues in Pisa in 1996, when he had obtained the help of a few researchers in the thorough investigations which had followed his spotting of the anomalous 105-GeV Higgs lookalike bump discussed in Chapter 11. Back then he had suggested that in exchange for the help of the Pisa researchers he would later help them with the SVT project. However, now he would not be able to join the efforts of the Pisa group in order to claim a share of their workload as a hardware contribution to Run 2: the Americans would consider it a fake commitment, based on an internal agreement between Italians members. One possible alternative was to get involved in the "fast tracker," a SVT-related project that the Chicago group was furthering, and which was short of personpower. But the Chicago leaders were not in favour. "Anybody but him!", they were heard saying. It is hard to blame them: they had gone nose to nose with Giromini too much in the past. A fruitful collaboration would simply be impossible.

In 2004 Franco Bedeschi was the coordinator of the Italian groups in CDF. Having served in the past as a CDF spokesperson, Franco knew how to push the right buttons of the Executive Board. He wanted to prevent Giromini from escalating the issue to the Fermilab directorate. Paolo had informed Franco that he would be asking for a new intervention of the new INFN president, Roberto Petronzio, who had in the meantime succeeded to Iarocci on July 1st; Paolo had expressed to the INFN president his feelings of being discriminated by the experiment because of the issues with his past searches for new physics. Petronzio, during a visit to Fermilab in November 2004, explained to Bedeschi that he was being asked to step in the discussion, something he wished to avoid; could Franco find a way to make it unnecessary? Bedeschi obliged: he collected the views of the representatives of the Italian institutions participating in CDF II -Pisa, Padova, Trento, Bologna, Trieste, Roma - and sent to Petronzio an open letter which stressed the importance of Giromini's contributions to the experiment, making it clear that the Italians in CDF would be able to handle the matter without his help. The letter described how the Italians had common views on the matter, and were united in the attempt to solve the issue to the satisfaction of everybody. Bedeschi made the point that Giromini had given an exceptional contribution to the realization of the CDF calorimeters and to data analysis, that he had contributed to many important measurements for the experiments, including the determination of the total and diffractive proton-antiproton cross section, the top quark search and cross section measurement; and that by standing united in seeking a solution to the issue within the collaboration, the Italian groups were confident they would bring the matter to a successful outcome.

Bedeschi's action ended up coalescing a consensus around the idea that Giromini had to be admitted after all. After further internal discussions and searches for a compromise, at the end of January 2005 the CDF II institutions expressed again their vote one way or the other by sending an e-mail to the spokespersons. The e-mail voting mechanism avoided the situation of the previous vote, which had proceeded by hand-raising. That procedure had put the American institutions in a position of advantage, due to their usually higher participation to Executive Board meetings for logistic reasons. The spokespersons had also done their math before asking for a vote. After discussing with all representatives, they knew that the collaboration was practically split in two; so it was with trepidation that they waited for the result: they feared that the question would become insoluble in case of a vote against the admission of the Italian scientist. In the end, of the 60 votes cast the majority voted to accept Giromini in CDF II. The margin, however, was quite narrow: this highlighted the big fracture that was still present within the collaboration, a fracture largely due to the Run 1controversies on superjet events. And this would not be the last time that a vote would need to be cast to decide on matters related to the Italian's scientific activities...