by Jean-Pierre Revol. Published: 31 January 2011

I am sure that Robert Bolt would have portrayed Jürgen Schukraft as an “ALICE Spokesperson for All Seasons”, as Jürgen managed to successfully drive the ALICE project for more than 18 years.

We just went through a phase transition in ALICE, characterised by three main events:

(1) First pp data on 23 November 2009 with ALICE managing to be the first to publish LHC pp collision data, followed in March 2010 by the first 7 TeV data and again the first LHC publication by ALICE of a measurement of global event properties of pp collisions at the highest energy in the world.

(2) First lead nuclei collisions at LHC in November 2010 and the first publication of LHC heavy ion data by ALICE, followed by four more publications by the end of 2010.

Of course, it was expected that ALICE would do well on heavy ion physics for which the apparatus is optimised, but it was a very satisfying feat to see that during the initial commissioning period of LHC, ALICE was actually on essentially an equal footing with the other three large LHC experiments, ATLAS, CMS and LHCb. This is a great achievement for the ALICE Collaboration, and Jürgen certainly deserves a significant part of the credit, even though it is also clear that none of this could have been done without the skill, hard work, and enthusiasm of the entire ALICE Collaboration.

This spectacular start of the ALICE scientific programme is a clear indication that the future will be bright! We have indeed entered the most exciting phase of our project.

(3) For the first time since the birth of the ALICE project we have a new Spokesperson! This is certainly another important parameter characterising this major phase transition.

As always, under such circumstances, it is a good time to reflect on the ALICE project and understand a bit better how all of this happened, and how we got as far as we are today, especially for the sake of the younger members of the Collaboration who did not live through the genesis of ALICE.

Selected dates in the history of ALICE

The genesis of ALICE was the result of a long process with contributions from many people. It took seven years between the discussions of first ideas in Aachen and the approval of the experiment in 1997 (pioneering phase), and another 12 years to build and install the detector and finally publish the first scientific results! I select here below only some of the significant dates in the history of ALICE.

– In Aachen, in October 1990, the first ideas for a heavy ion experiment were presented by GSO physicist Hans Specht.

– There was an important heavy ion meeting organized at CERN by Jürgen on 13 December 1990, attended by 60 physicists.

– Another important meeting was held in Lund, in March 1991; and the same year, there was a so-called DELPHI workshop at CERN discussing the possibility of using the LEP DELPHI detector as a heavy ion detector at the LHC.

– In December 1991, the CERN Council made a very important statement concerning the LHC: “LHC is the right machine for the future of CERN”. This was a major step towards the approval of the LHC.

– The Evian workshop in March 1992 can probably be considered as the formal start of the LHC experimental programme, as for the first time Expressions Of Interest were presented by a number of proto-collaborations, and, at that meeting, Jürgen presented the heavy ion Expression Of Interest, a project with no name yet, the name “ALICE” would be chosen later on.

– There were several potential candidates for the post of ALICE Spokesperson: Hans Gutbrod, Emanuele Quercigh, Jürgen Schukraft, Hans Specht, Reinhard Stock, perhaps even others whom I do not know. But on 1 May 1992, it was Jürgen who was elected, as witnessed by one of the many Champagne bottles in his office, bearing this date. Jürgen was the youngest LHC Spokesperson. On the same occasion, Hans Gutbrod was elected as deputy.

– The ALICE Letter Of Intent was submitted on 1 March 1993, with a revised version one month later, on 31 March1993.

– On 15 December 1995, the ALICE Technical Proposal (CERN/LHCC 95-71) was submitted, and its Addenda in 1996 and 1999 respectively (CERN/LHC 96-32 for the muon arm and CERN/LHCC 99-13 for the TRD).

– A major milestone for CERN was the approval of the LHC project (forgetting the computing which was to be at the origin of a financial crisis later on!) in 1994.

– On 20 April 1994, Emanuele Quercigh was elected Chair of the ALICE Collaboration Board, with Ingvar Otterlund as deputy.

– On 7 June 1995, the ALICE Collaboration Board extended the terms of Jürgen Schukraft and Hans Gutbrod until completion of the Technical Proposal.

– The Resources Coordinator, Hans de Groot, put in place a whole new system for dealing with resources in large collaborations resulting in a series of Memoranda Of Understanding (Interim MoU: 14 April 1998; Construction MoU: 31 May 2000; M&O MoU: 24 May 2002; Computing MoU: 29 March 2005).

– A major year for ALICE was the formal approval of the project in 1997.

– A series of 14 Technical Design Reports (TDR) was to follow (First TDR 1998 – HMPID, last TDR in 2008 – EmCal).

– The scientific programme had to be matched to the performance of the real detector, as well as being updated to take into account surprising RHIC results, which started coming out in 2000. So, in 2004–2006, the ALICE Physics Performance Report was written and published in EPJC.

– On 23 November 2009, the first proton–proton collisions were registered by the ALICE detector at a centre-of-mass energy of 900 GeV. This was the start of the ALICE scientific programme at the LHC.

– On 30 March 2010, ALICE collected the first data with 7 TeV proton–proton collisions.

–On Sunday 7 November 2010, around 12:30 AM, 20 years of hard work were rewarded by the first collisions of lead nuclei at the LHC, at a centre-of-mass energy of the nucleon–nucleon system of 2.76 TeV, which corresponds to an unprecedented energy involved in the collisions, a total of about 574 TeV! No black hole was reported in the Geneva area!

The evolution of the Spokesperson’s role

The role of the Spokesperson evolves with the evolution of the project. Being Spokesperson at the birth of a new, large, experimental collaboration is certainly a most challenging responsibility, requiring very specific skills:

– A good taste for physics and a clear vision of the future of the project

– Political skills (even though, in my opinion, there is too much politics in our large collaborations)

– A talent for selecting excellent collaborators, especially those who are able to keep you on track, and this is particularly true of the Physics Coordinator.

– An ability to set priorities, in order to choose amongst conflicting requirements

– Infinite patience, which has to increase proportionally to a high power of the number of collaborators

– Being stubborn when needed. Do not let people derail your train when you know it’s on the right track.

Believe me, Jürgen possesses all these qualities! It is not unusual to find physicists with some of these qualities, however, it is rather unusual to find them all concentrated in one single individual. For all these reasons, Jürgen was an excellent Spokesperson.

Early detector ideas

The evolution of the ALICE detector concept has been very strong over a period of 20 years, and what we have today at Point 2 resembles only vaguely what one can see on the sketch presented by Hans Specht at the Aachen Workshop in 1990 (Figure 1). The tracking was outside the B-Field, the ? acceptance was very small (|?| ? 0.4–0.5), but the concept of a forward muon arm was already there, at least in one of the designs.



Figure 1: Early concept of a HI detector at LHC. “open axial field magnet in conjunction with a forward ?-spectrometer”. H. Specht, Aachen 1990.

In Evian in 1992 the detector design went one step closer to the final version, but it was obvious that the Collaboration did not want to take any chances with unproven possibilities, such as jet quenching discussed by Helmut Satz at the same workshop, but not yet discovered by RHIC. So no calorimeter was foreseen (Figure 2). Jürgen has always been very careful with money, which is probably the main explanation for why the magnet was inside the TPC, which made the design cheaper. Money, money, money …



Figure 2: Heavy Ion detector design presented by Jürgen at the Evian Workshop in 1992. Note the magnet inside the TPC.

To be fair, jet physics was mentioned in the presentation, but it was assumed that it would be performed without a calorimeter, using tracking with charged particles only. Today, fortunately, this has been corrected and ALICE is now equipped with an electromagnetic calorimeter (EmCal) that was just completed in the 2010 Christmas break.



Figure 3: Evian LHC Workshop, 1992, extracted from Jürgen Schukraft’s presentation.

However, Jürgen also wanted to play it safe. Even though Helmut Satz had predicted at the same conference a particle multiplicity not too different from the one observed (dn/d? =1500–2500 at ?s = 6.3 TeV), Jürgen announced at the conference that the detector should be able to cope with dn/d? up to 8000 (Figure 3), a bold step where no detector had gone before! Today we know that for central Pb–Pb collisions, at ?s = 2.76 TeV, dn/d? = 1584, so we are all very much relieved.



Figure 4: Concept of the ALICE detector (From Lars Leistam’s presentation at the Dec. 2009, ALICE CERN Team meeting).

The only way Jürgen could achieve this within a reasonable budget was by saving on the cavern and on the magnet, using the L3 experimental cavern, and the existing L3 magnet (Figure 4). However, this great saving added some significant space constraints on the design of the final ALICE detector. This led to the still rather theoretical 1995 sketch shown in Figure 5. No support structures! No services! But getting close to what we are familiar with today.



Figure 5: 1995 detector design, from Technical Proposal (CERN/LHCC 95-71).

In the end, it took the hard work of four Technical Coordinators, starting with Wolfgang Klempt, followed by Chris Fabjan, Lars Leistam who was also in charge of installation and integration for many years, and Werner Riegler, to transform dream into reality (Figure 6).



Figure 6: The present design of the ALICE detector.

The qualities of a Spokesperson certainly include patience. Jürgen had to deal with a continuously receding LHC starting date.



Figure 7a: LHC planning (Giorgio Brianti, Aachen Workshop, 4–9 October 1990).



Figure 7b: Experiment planning (Lars Leistam, Aachen Workshop, 4–9 October 1990).

The LHC went from a start date for the machine of early 1998 at the time of Giorgio Brianti (Aachen Workshop, 4–9 October 1990, Figure 7a) matched without any problem by a detector construction and installation schedule prepared by Lars Leistam, at the same conference (Figure 7b), to the real start in November 2009.

Jürgen’s patience seemed to have no limit, given that he had to deal with a 12 year delay of the LHC, and survive many CERN Directors-General (Figure 8), who were all trying their best to achieve a startup of LHC during their mandate:

– 1998 was the date considered by Giogio Brianti, during Carlo Rubbia’ term – Remember that one had to take into account the fierce competition with the American SSC at that time

– 2002–2006 Chris Llewellyn Smith (the date moved by two years during his term because Germany asked for a 10% reduction of the CERN budget)

– 2007 Luciano Maiani

– 2008 Robert Aymar false start (LHC accident)

– 2009 Rolf Heuer, real start; ALICE first data with pp at ?s = 900 GeV

– 2010 Rolf Heuer, heavy ion start, just in time for the Quark Matter Conference in Annecy, in May 2011

Amongst the qualities of a Spokesperson, one also needs a special skill: being able to carefully choose key collaborators, which Jürgen did year after year, going through four Technical Coordinators, two Physics Coordinators, two Resources Coordinators, two Collaboration Board chairs (Figure 8). However, he had no choice about CERN team leaders who were imposed by the Physics Department management. It turned out that Jürgen and the team leaders formed a very good team, able to solve almost any problem, be it technical, financial, or human, and there were many over Jürgen’s very long term as Spokesperson.



Figure 8: Technical Coordinators, Resources Coordinators, ALICE Collaboration Board Chairs, CERN Team Leaders, and CERN Research Directors during Jürgens’s mandate as ALICE Spokesperson.

Jürgen also had to survive an impressive number of CERN Research Directors (Figure 8). I am told that his survival skills also apply in some totally different environments, such as high mountains and wild forests in various parts of the world, where he would sometimes mysteriously disappear for a few weeks. Not so surprising for someone who can survive so well in our research environment.

Of course, a Spokesperson needs to be able to survive crises, and you can be sure that there were many in 18 years. I personally remember two of them, that were particularly tough: DAQ vs HLT architecture and ROOT vs OBJECTIVITY for the computing framework (or René Brun and Federico Carminati against the rest of the world, and today nobody is using OBJECTIVITY in LHC experiments!).

In this context, Jürgen accomplished real miracles, as testified by the recent photo of the DAQ and HLT coordinators (Figure 9), illustrating the spirit of collaboration between the two projects today.



Figure 9: Photo of Pierre Vande Vyvre (DAQ project leader – left), and Volker Lindenstruth (HLT project leader – right) in a heated discussion over the interface between the two systems.

The final important quality of a Spokesperson that I would like to mention is the ability to keep a child-like spirit, and this Jürgen could do almost continuously, as we can see for instance in Figure 10.



Figure 10: Jürgen keeping a child-like spirit at all times (Left: Erice, September 2000) and in all places (Right: Vallée Blanche, 1984).

Jürgen leaves the post of ALICE Spokesperson with a large and well structured Collaboration (~1000 members) and a superb detector, essentially complete and operational, and a number of important publications which clearly place ALICE on the same footing as the other LHC experiments. Today, 50% of the TRD is still to be completed, but the TRD was only initially approved at 50%, so the remaining 50% is a late addition to ALICE, and two out of five PHOS modules are still missing due to a lack of resources (the price of lead-tungstate crystals went up considerably) but the Collaboration has not yet given up on them.

So indeed, Jürgen leaves with an incomplete detector: nobody’s perfect! But we all agree that it is close enough to perfection. Paolo Giubellino, the new ALICE Spokesperson, inherits a Collaboration and a detector both in excellent shape but with a different mission centred on physics exploitation and detector upgrade for even more physics in the future. We clearly are only at the beginning of a great scientific adventure. We have to be ambitious and evolve our detector to follow the requirements of the new physics we are discovering. This is a pretty exciting new phase of our project.

Now, I would like to turn to questions everyone is asking about Jürgen. How did he manage all this? What is the secret explanation behind such success? In my view, it has probably to do with Jürgen’s special connection with some aspects of the feminine gender, pervading his work! In one of his publications with the Helios Collaboration studying diffraction in proton–nucleus collisions, he clearly revealed a certain obsession with the feminine world, naming his Monte Carlo event generator “Iris”. This strange fact, unnoticed at the time, was only partially explained years later, when some interesting information finally got published by Wikileaks. But other findings remain totally mysterious, such as this apparent membership of the “Ordre du Temple Solaire” (Figure 11), not mentioning even more mysterious events (Figure 12).



Figure 11: Jürgen and the “Ordre du Temple Solaire”, undated photo from the “Répertoire suisse des signalements de personnes”.



Figure 12: Jürgen’s enthronement at a secret place in India.

One can only imagine Jürgens’s dilemma when it came to choosing a name not only for his computing code but for his professional companion of more than 20 years, his experiment. It must have been a hard choice between Alice … Iris … Alice … Iris … Iris …

Alice won on the professional floor, but only one woman in the end managed to cut his hair (and beard) (Figure 13) …. and there is a strong suspicion today that Jürgen is actually living with both Iris and Alice (Figure 14), but this is a private matter, and we should leave it at that.



Figure 13: Jürgen about to be sacrificed by Iris at an unknown location in Thoiry, in 1986.



Figure 14: Jürgen and Alice, looking at her with undisguised excitement …

Thank you Jürgen for all you have done. You clearly showed us the way to success (Figure 15). We hope you will now enjoy the fruits of your long efforts, analysing all the data ALICE is going to collect in the next 10 years, or longer.



Figure 15: Jürgen showing the way to the future of ALICE after a first long mission well accomplished.

A new Guinness World Record



The longest time as Spokesperson of an LHC experiment, for Jürgen Schukraft!

The tendency today is to change Spokesperson as often as possible, which at one point may make it irrelevant who the Spokesperson is, but will certainly make Jürgen’s record impossible to break.

Jean-Pierre Revol

ALICE CERN Team meeting, 26 January 2011

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Comments

Jurgen

I liked Jean-Pierre's account of Jurgen role in ALICE. He succeeded in the difficult task to picture the many facets of Jurgen from the designer to the builder to the driving force behind the physiacl ideas. personally I am reflecting on Jurgen's age at the time he took the task. He was invested with a task he fullfilled perfectly and we should bear that in mind when choosing new leaders.
Thanks Jurgen for your performance and thanks to Jean Pierre for the beautiful text.