BaBar AND International Collaboration

OrHow David Leith carried out “an experiment within an experiment” and

made possible the BaBar we know.

But first…..• My sincere thanks to David MacFarlane and SLAC for inviting me to

join you today.• I am delighted to be here and greatly honoured to have been invited.• But – I don’t have any photos of us at that time…..

• I first met David in 1975• I’d come to SLAC to see the capacitive spark chambers used in first phase of

LASS• We’d made some, but the LASS ones were better!• By the early 90’s SLAC was at the height of its powers and reputation: a

place of pilgrimage with its 3 Nobel prizes and its star-spangled faculty.• Europe had just finished LEP and was preparing for the LHC – and there

was to be a big gap between the two, yet there was good science still to be done. • We knew of the plans for the Tevatron Main Injector, and some groups

migrated to work on CDF or D0. • We knew of the plans for PEP II and many groups in Europe were sniffing

around the USA to see what opportunities there might be. At the same time, of course, the US community was looking towards the LHC following the cancellation of the SSC in 1993.

• So the time and circumstances were ripe for increased formal collaboration across the Atlantic divide.• Enter David, Research Director at SLAC, who had the vision to see an

opportunity in BaBar, an ambitious project on the same scale as, say, a LEP experiment, to measure the parameters of CP violation in the B0

system using the purpose-built PEP II accelerator which had been authorised by Congress in 1993.• PEP II was to start in 1998 and BaBar shortly thereafter. It would be

no exaggeration to say that the future of SLAC as a particle physics centre of excellence, and perhaps even of the US particle physics community, depended critically on the success of PEP II and BaBar. So it was indeed a bold step, fortunately backed strongly by the SLAC Director (Burt Richter) and the DOE (John O’Fallon).

• David set out, with enormous energy and total conviction, to build international support for an international collaboration to construct and operate BaBar. • I don’t remember how much this was driven by pragmatic resource

constraints and how much by an idealistic view of the importance of international collaboration in the development of science – knowing David, it’s certain that the latter figured highly in what was probably a bit of both. • It is hard to appreciate now just how big a cultural leap this probably

was. Up until then the European and US particle physics efforts had operated in almost separate universes. • Following the cancellation of the SSC it was becoming clear this

situation would have to change.

• David didn’t just want European (and other) groups to participate in a SLAC experiment. • He wanted a new collaboration, hosted by SLAC and using SLAC infrastructure,

but conceived and managed ab initio as an international collaboration with its own modus operandi. • In this, LEP was probably a good model, but there is a very big difference

between an international organisation like CERN and a DOE funded lab like SLAC. So there was an element of risk in the implicit culture clash.• David, accompanied by David Hitlin, made a tour of major European and other

labs to test the water and drum up support. George Kalmus and I met David2 at the Rutherford Lab on 23 March 1995, following extensive discussions between interested UK groups and the US BaBar team.• They toured Europe and enlisted France, Germany, and Italy to join UK, Canada

and the US and commit to significant contributions. It’s a testimony to David’s persuasive powers that groups from China, Norway, Russia and Taiwan also joined the party, albeit at different times.

• David had a clear idea of the structure of the BaBar collaboration and he gave us a draft MoU and the ‘Conditions for Experiments at SLAC’. • The core body would be the International Finance Committee, chaired by David

with membership from the various national funding agencies, which was to exercise policy oversight and overall financial control, particularly of the Common Fund. • There would be the usual scientific bodies for Babar and, of course, the internal

and DOE mandated bodies for the construction of PEP II. • These were quite independent of the IFC, but it obviously received status reports

from the SLAC Director and Jonathan Dorfan, in charge of the PEP II programme.• The IFC met for the first time on 21/22 April 1995, very soon after David2 had

made their epic tour of Europe. It was immediately clear that BaBar had a very serious problem with the funding profile, particularly with the (cash) Common Fund, a problem that was to pursue the project throughout its history.• And the Europeans, as CERN Member States, were used to CERN offering more

services than SLAC could reasonably be expected to provide.

• Indeed, at the next IFC in November 1995 we saw that “the biggest single issue is the timescale that can be achieved for BaBar with the anticipated funding, and in particular how the ‘aggressive’ timescale can be maintained in the face of obvious mismatches in cash flow”.• Undaunted, we carried on under David’s excellent leadership.• The IFC rapidly became a coherent body which functioned extremely

well in the interests of BaBar, and was able to deal with issues as they arose in a constructive manner, because we largely knew each other very well and were steeped in the culture of CERN and DESY collaboration. • The IFC met twice a year and so was able to keep pretty closely in

touch with developments. SLAC proved very open and cooperative and we never felt side-lined by the bigger issues.

• The IFC meetings were tough, sometimes very tough, but David was an excellent Chair and gave gentle leadership throughout, keeping us focussed and wherever possible guiding us towards an effective solution. • Sometimes this involved delicate overnight discussions with the SLAC

management and DOE when the project was in a particularly tricky situation and immediate action was required. • The IFC respected and appreciated the work being done by David and

SLAC management to keep the show on the road. • Here I should pay tribute to both SLAC and DOE for their unwavering

support – we are truly appreciative and this was a major contribution to the success of BaBar.

• David made an enormous contribution to the success of BaBar as an international collaboration. • BaBar would probably have happened, because the physics case was

absolutely compelling, but without David’s work it would have been very different indeed. • Although the IFC meetings were the principal focus, he was working hard

in the background in many other ways, many of which we didn’t know at the time and for which I don’t think he always got the credit he was due. • David has an imposing physical presence – a gentle giant indeed – but he

also had a powerful intellectual presence in the collaboration. He was receptive to ideas but firm in his views, creative in finding solutions but resolute in implementation, flexible when necessary but determined in his objectives. • And always a pleasure to work with!

• Back to BaBar itself …..• The timescale was aggressive. President Clinton approved the B-factory

in October 1993. The inaugural meeting of the detector collaboration was held at SLAC in December 1993, at which time the 9 nation BaBar collaboration began. First funding for PEP II construction was released in January 1994. The detector technical design report was completed in March 1995.• PEP-II was completed in July 1998 and first collisions were observed on

July 22, 1998. Commissioning without BaBar concluded in February 1999, at which time the BaBar detector commissioning ceased. BaBar started physics in early May 1999, and first collisions with BaBar were observed on May 26, 1999. This is perhaps a year or so late, but given the various issues encountered and overcome, this surely counts as a very positive result.• The first paper was published in 2001 (I think!)

• Were PEP II and BaBar successful? I can quote from John Seeman speaking in 2008:

“The design luminosity was reached after one and a half years of operation. In the end PEP-II surpassed by four times its design luminosity reaching 1.21 x 1034 cm-2 s-1. It also set stored beam current records of 2.1 A e- and 3.2 A e+. Continuous injection was implemented with BaBar taking data. The total delivered luminosity to the BaBar detector was 557.4 fb-1 spanning five upsilon resonances.”

• BaBar is still publishing – as I write there are 550 records on oraweb.slac, covering far more physics than the original CP violation goal. BaBar has recorded some 500 million B-Bbar pairs. • There is a joint BaBar-Belle document “The Physics of the B factories”, a 928

page tome, which exists in pre-print form on http://arxiv.org/ftp/arxiv/papers/1406/1406.6311.pdf.• I can sincerely recommend it as bedtime reading …….but only for specialists

or insomniacs!

• So, to return to David – was BaBar a success? • I quote from David’s valedictory letter of 17 February 2000,

when he stood down as SLAC Research Director and relinquished the Chair of the IFC:

“It has been an experiment, by itself, on how the lab manages international collaborations. I have been very pleased and very proud of how this experiment-within-an-experiment has worked out”.

•We can only agree wholeheartedly, and say “Thank you, David”.