Obituary of Peter Schlein

Friends and colleagues were shocked and deeply saddened by the unexpected death of Peter Schlein on 26 February 2008. Peter was a highly respected particle physicist who started his long career on emulsion experiments and continued on to bubble chamber, fixed-target and hadron-collider experiments. His best-known efforts included his role in founding two fields: the partonic structure of the Pomeron and forward B-particle production.

Peter was born in Brooklyn, New York, on 18 November 1932, the eldest of four sons. His father, Irving Schlein, was a neo-classical composer, Broadway musical conductor, and teacher. After graduating from Union College in Schenectady, New York, Peter received his PhD from Northwestern University in Evanston, Illinois. He worked as a postdoctoral researcher at the University of California, Berkeley, and Johns Hopkins University before joining the physics department at University of California Los Angeles (UCLA) in 1962.

Peter’s research was unique. Had he not pursued it, much of the work in his field would probably not have been done or would have been undertaken at a much later date — and it would certainly have lacked his distinctive style. He took sabbatical leave from UCLA in 1969 at CERN to work at the ISR. The experiment was so fascinating for him that he continued the collaboration, dividing his time between CERN and UCLA. He went on to construct the first wide-aperture forward spectrometer at the ISR in 1973–74, and this was to influence much of his future research. In the mid-1970s, he returned to the US where he collaborated on the fixed-target experiment E260 at Fermilab. He later returned to CERN to build the second-generation forward spectrometer to observe the Λ_c baryon and to study forward systems.

After the closure of the ISR, and excited with the results of his R608 experiment on diffractive dissociation of protons, he and Gunnar Ingelman proposed that the Pomeron, which is exchanged in such interactions, should have partonic structure. Like any other strongly interacting particle, this partonic structure could be measured experimentally by observing jets in this class of interactions. He proposed and constructed the UA8 experiment at the SppbarS Collider at CERN to observe the jets produced in diffractive interactions. This saw the first use Roman Pots Experiment to trigger a central collider experiment. A very clean signal for jets in diffractive dissociation was observed with the first year’s data and the new field of “hard diffraction” was born.

Before data-taking on the UA8 experiment was completed, Peter started thinking of studying B mesons and CP violation in hadron colliders, at a time when many physicists were planning to build e+e- colliders to study the same physics. Over the next few years, he directed the R&D programme that developed the topology trigger and the silicon system deployed a few millimetres from the circulating beams, two major obstacles for studying B Mesons in hadron colliders. His series of proposal for a B Experiment experiment at the SPS, Fermilab, and RHIC at Brookhaven eventually formed the basis of the plan for the LHCb expriment that will start data taking at LHC this year. Peter left the LHCb experiment because of lack of US support and along with his UCLA colleagues instead joined another LHC experiment, CMS, where he once again concentrated on forward physics.

Peter spent four decades with the UCLA physics department, where he left a strong impression. Over his career, he brought several notable faculty members to the department, and his impact was evident on the younger generation of faculty who were regularly asked by outside colleagues, “How is Peter doing”?

Near the end of his career and during his retirement, Peter turned his boundless energy towards reviving the legacy of his father’s classical music. He catalogued hundreds of old scores and recovered lost pages from a variety of musical sources. He befriended many of the top musicians and musicologists in St. Petersburg, Russia, transcribing all the scores into digital form, and commissioned performances and recordings by members of the St. Petersburg Philharmonic. In all, Peter produced 14 CDs of his father’s works, which are now being performed by musicians around the world. He was as proud of his accomplishments in creating “a new page in American music” as he was of his career as a physicist. With boundless energy and unstinting enthusiasm, he brought the beauty and originality of his father’s musical works to the attention of an audience that never knew of their existence. This new work of musical discovery remains a work in progress and will add to Peter’s legacy.

Peter Schlein was a devoted family man, and he leaves behind his wife, Lisa, his children, Oren and Ilana, five grandchildren and three brothers.