University of Michigan honours Alan Krisch

On 14 November 2009, colleagues and friends from around the world gathered at the University of Michigan in Ann Arbor for a Spin Physics Symposium to honour Alan Krisch, who recently turned 70.

After gaining his PhD at Cornell under Giuseppe Cocconi, Alan moved to Michigan in 1964 and has stayed there ever since – as a full professor for the past 41 years. The first part of the symposium centred on Alan’s many important contributions to spin-physics, after a first talk in which Homer Neal reminded the audience of Michigan’s long association with spin: from Uhlenbeck and Goudsmit, Dennison and Crane, to the recent activities in high-energy, nuclear and atomic spin-research.

Michigan’s Carl Akerlof reviewed Alan’s early experiments. The first was his 1962–63 thesis experiment at Brookhaven’s Alternating Gradient Synchrotron (AGS), on 30 GeV large-angle proton–proton elastic scattering. This was followed by the 1965–66 measurement of π-p elastic scattering at 180° for different momenta at Argonne’s Zero Gradient Synchrotron (ZGS). It was Alan’s first experiment as spokesperson, at the age of 25 – an outstanding success “that put the ZGS on the map", as Argonne’s former high-energy physics director Malcolm Derrick commented. The 1966 experiment on proton–proton elastic scattering at 90°cm showed a kink in the elastic cross-section near a beam momentum of 8 GeV/c: the first evidence for objects (or layers) inside the proton.

Marvin Marshak of Minnesota recalled Alan’s first “p + p → p/π/K + anything" experiments at the ZGS to test his so-called “onion" model. It did not confirm Alan’s prediction that heavier particles were produced in the proton’s inner layers, but the papers in Physics Review Letters of 1967 and 1968 contained the first definition of the concept of “inclusive" cross-sections (the name “inclusive" being coined later by Richard Feynman).

Alan pursued inclusive measurements at much higher energies at CERN’s Intersecting Storage Rings (ISR) in the Argonne–Bologna–CERN–Michigan collaboration. The Argonne–Michigan team was the first from the US to work at the ISR and the collaboration was among the first to take data in 1971.

Marshak recalled how the ZGS appeared in 1960 as a unique facility for accelerating polarized protons but it had to wait for a driving force like Alan to develop the world’s first high-energy, polarized-proton beam in the years 1970–1973, along with Larry Ratner, Everett Parker and many others. Alan embraced the idea that the structure being suggested by the experiments could best be probed by preparing either the beam or target protons, and later both, in a specific spin state. Michigan’s Polarized Proton Target (PPT) used dynamic nuclear polarization, a technique first developed at Saclay and Berkeley. In six years there were a total of 43 polarized-proton and four polarized-deuteron experiments conducted at the ZGS. It was then (1974) that Alan started the series of Spin Physics Symposia, where progress and ideas are still debated today. Alan was leader of the effort – together with Larry Ratner, Kent Terwilliger, Ernest Courant, Vernon Hughes, Thomas Roser and many others – that led to the acceleration of the first strong-focusing polarized proton beam at the AGS during the years 1978–1985.

Alan was right. As Don Crabb of Virginia commented, Alan’s team found large spin effects in double-spin experiments at the ZGS. First, they found a large spin-dependence in the transversely polarized pp total cross-section. Then, in 1977 and 1978, at 12 GeV/c, near 90°, they found the spin-parallel pp elastic cross-section σ(↑↑) to be four times larger than the anti-parallel spin cross-section σ(↑↓). A similar experiment with the scattering angle fixed at 90°cm confirmed that the huge spin effect was a result of the hard scattering of the proton’s constituents, and not a consequence of particle identity. However, this σ(↑↑)/σ(↑↓) ratio was a factor of two too large to be caused by three spin-  quarks in the quark-interchange model proposed by Stan Brodsky and others.

Large spin effects were also found at the AGS after the ZGS shut down in 1979. Alan’s team studied the single-spin elastic cross-section’s up–down asymmetry An = (σ↑-σ↓)/(σ↑+σ↓): An was growing rapidly at large transverse momentum, in contradiction with QCD. To confirm the data, the team developed a radiation-doped ammonia PPT, working at 1 K in a 5 T magnetic field, which could be used in a beam of 1011 protons/s (20 times more intense) with an average polarization of 85%. The large and growing An was confirmed with higher precision.

Then, following Alan’s long-standing interest in “Siberian snakes", the team moved to the Indiana University Cyclotron Facility to study spin manipulations with collaborators from Indiana (1986–2002). The acceleration and successful collision of the world’s first beams of 100 GeV (and then 250 GeV) polarized protons at Brookhaven’s RHIC is a direct fall-out from the research by Alan and his collaborators. Thomas Roser discussed the first test in 1989. These studies were continued in 2002–2009 at the Jülich Cooler Synchrotron. Hans Ströher of Jülich, in a paper delivered by Dennis Sivers, reviewed the highlights, including the very high-efficiency proton spin-flipper, and the spin-manipulation of tensor-polarized deuterons.

In the afternoon, the symposium reviewed the present and future status of spin physics, with talks by Jacques Soffer, Naomi Makins, Richard Milner, Jonas Sandberg and Abhay Deshpande.

Engaging nature’s huge problems, sceptical, meticulous, innovative, persistent: that is how Michigan’s Homer Neal summed up Alan, when offering him a spin-inspired sculpture made in the Michigan workshop at the end of the symposium.

For the full programme and all the talks, see http://spin-symposium.physics.lsa.umich.edu.


Ankara hosts inaugural ISOTDAQ school

The 1st International School of Trigger and Data Acquisition (ISOTDAQ) took place on 1–7 February in Ankara. This pioneering project was an initiative by CERN’s Turkish community and became possible through major contributions from CERN and various members of the LHC experiments. The project was jointly funded by the ACEOLE project under the Marie Curie Action Fellowship Programme, CERN, the Turkish Atomic Energy Authority (TAEK) and Bog˘aziçi and Çukurova Universities. TAEK hosted the event.

This new school’s target audience is masters and doctoral students who intend to continue their careers in the field of accelerator physics or particle physics, specializing in trigger and data acquisition. The topics covered included trigger hardware and software, data-acquisition hardware and software, and data-transfer technologies. The school attracted some 100 applicants from 11 nations, of whom 40 were selected.

With the aim of striking a balance between theory and practice, the lectures were accompanied by 11 lab sessions, each 2 hours long. The lab equipment was shipped from CERN (half a tonne) and supporting universities. The labs covered different topics, such as finite-state machine (FSM) design, field-programmable gate-array programming, and cosmic-muon measurements using VME-bus technology. Twenty-seven experts from all four major LHC experiments and CERN volunteered as lecturers and lab instructors.

A pre-school lecture programme took place one day before the school started to prepare the students with the necessary computing skills. Over the next seven days, the participants gathered on the 11th floor of the TAEK headquarters to attend lectures and take part in the lab sessions, engaging in lively debates on the various topics covered during the lectures. “Get your hands dirty," said Gökhan Ünel aptly in his welcoming speech at the opening ceremony, quoting Confucius as the motto for the school: “I hear and I forget. I do and I understand."

The students were also treated to an excursion day to the city of Ankara for a taste of traditional Turkish cuisine and culture. This included visits to the Museum of Anatolian Civilizations and the mausoleum of M K Atatürk, the founding father of the Turkish Republic.

On the last day of the school, the instructors were pleasantly surprised by a humorous closing lecture from the students before the school was brought to an end with a ceremony where participation certificates were presented to the students. Each student also received a minimalist TDAQ device as a gift from the school. This hardware is meant to encourage the students to express their own creativity. Those who successfully complete a project with it within two weeks will also receive an achievement certificate from TAEK.

This inaugural school received a positive evaluation from the students and encouraging feedback from the TDAQ community. It also caught the attention of the Turkish national radio and television network, TRT. Extensive interviews with students and instructors appeared in a documentary aired in March. What started off as an ambitious project has turned out to be a remarkable learning process for everyone involved. The event’s success has laid a solid groundwork for turning it into an annual school, with the next ISOTDAQ scheduled for 2011.

For slides and video recordings of the lectures, see http://isotdaq.web.cern.ch.