dimensions volume 04 of particle physics symmetryA joint Fermilab/SLAC publication issue 10 december 07 symmetryA joint Fermilab/SLAC publication On the cover The ALICE Time Projection Chamber Photo: Antonio Saba, CERN Inside front cover Model of a superconducting quadrupole magnet for the Large Hadron Collider project. These magnets are used to focus the beam by squeezing it into a smaller cross-section, similar to the way a lens focuses light. However, each magnet focuses the beam only in one direction so alternating magnet arrangements are required to produce a fully focused beam. Photo: CERN Office of Science U.S. Department of Energy volume 04 | issue 10 | december 07 2 Editorial We are on the eve of one of the greatest experiments in the history of physics. The Large Hadron Collider is pushing the frontier of exploration into the fundamentals of our universe. 3 Commentary: Lyn Evans “ Although the majority of the LHC was produced in Europe through collaboration between CERN and industry, a walk through the accelerator tunnel tells an international story.” 4 Signal to Background Not just about aliens anymore; life among physics tribes; Spartan software; connecting with Africa; the LHC by mail; penguins and particles; two new directors. 8 Voices: Dennis Overbye What’s in a name? Parsing the ‘God Particle,’ the ultimate metaphor. 10 Across the Ocean, Yet Close to Home Among the 10,000 people working on the Large Hadron Collider, 1000 hail from universities and national labs in the United States. 14 Entering Higgs Habitat The LHC will allow scientists to explore the territory where the long-sought Higgs particle—or maybe even a whole family of them—resides. 18 Protecting the LHC From Itself While human safety is always the first concern at the Large Hadron Collider, the machine also needs shielding from its own proton beams, which pack the energy of high-speed trains. 24 Gallery: In the Labyrinth It’s heavy, dusty, dirty work: Deep in the bowels of the LHC detectors, workers are connecting a rat’s nest of cables. 28 Q&A: James Gillies Hollywood directors, time travelers, journalists, school kids—CERN’s press office sees them all. 30 Essay: Peter Steinberg “The fascination with the LHC should not just be in the results, but in the false starts, inevitable stumbles, and occasional flashes of insight about the physics. Stay tuned to the bloggers, both official and not, as the LHC and its detectors rumble to life.” ibc Logbook: CMS Cosmic Challenge Scientists working on the Compact Muon Solenoid test the detector using particles that rain down from space. bc Explain it in 60 Seconds: Terascale The Terascale is an energy region named for the tera—or million million—electronvolts of energy needed to access it. Physicists are standing at its threshold, poised to enter this uncharted territory of the subatomic world. from the editor The LHC: The greatest physics experiment of history We are on the eve of one of the greatest experiments in the history of physics. The Large Hadron Collider, a 27-kilometer ring straddling the Swiss-French border, is pushing the frontier of exploration into the funda- mentals of our universe. The machine is currently being prepared for first injection of the high- energy proton beams, due in the next few months. Soon after, the largest detectors ever made will be peering into the debris of collisions, a tangle of data that physicists will dissect, examine, and probe in their journey to reveal long-sought secrets of nature. In recent years, particle physics has been revolutionized with the dis- covery that 95% of the universe is missing. The Large Hadron Collider will answer many significant questions about the part of the universe we know and start to reveal critical information that will guide our exploration of the rest. The LHC will answer much, but it will raise just as many new questions for the ongoing scientific enterprise. Projects like the LHC are almost indescribably complex, requiring many tens of thousands of person-years of effort. Experiments on this scale need a long-term, consistent commitment to make them feasible. CERN has built an outstanding structure for managing large-scale, interna- Phioto: Reidar Hahn, Fermilab tional collaboration, and the pursuit of scientific goals through this means has brought many additional non-scientific benefits to the partners and society as a whole. This issue of symmetry is dedicated to the imminent switch-on of the Large Hadron Collider. It can only skim the surface but presents views of the science, technology, international collaboration, and humanity of the LHC. Although not a CERN member state, the United States has one of the largest contingents of scientists working on the LHC. In the fiscal year 2008 federal budget, the United States fully honors its commitment to the LHC program. However, last minute cuts to the science budget, made as a consequence of political tussles, seriously threaten the future health of high-energy physics (and other sciences) in the United States. Whether the US government is able to justify its claim to support the physi- cal sciences, and whether it will be able to generate confidence in itself as a good partner in international scientific projects, hangs in the balance. However, science goes on, and the promises and opportunities of particle physics are now greater than at any time in the past few decades. David Harris, Editor-in-chief Symmetry Editor-in-Chief Publishers Print Design and Production PO Box 500 David Harris Neil Calder, SLAC Sandbox Studio MS 206 650 926 8580 Judy Jackson, FNAL Chicago, Illinois Batavia Illinois 60510 USA Deputy Editor Contributing Editors Art Director Glennda Chui Roberta Antolini, LNGS Michael Branigan 630 840 3351 telephone Peter Barratt, STFC 630 840 8780 fax Managing Editor Romeo Bassoli, INFN Designer www.symmetrymagazine.org Kurt Riesselmann Stefano Bianco, LNF Aaron Grant [email protected] Senior Editor Kandice Carter, JLab Web Design and Production (c) 2007 symmetry All rights Tona Kunz Reid Edwards, LBNL Xeno Media reserved Suraiya Farukhi, ANL Hinsdale, Illinois Staff Writers James Gillies, CERN symmetry (ISSN 1931-8367) Elizabeth Clements Silvia Giromini, LNF Web Architect is published 10 times per Heather Rock Woods Youhei Morita, KEK Kevin Munday year by Fermi National Kelen Tuttle Marcello Pavan, TRIUMF symmetry | volume 04 issue 10 december 07 Accelerator Laboratory and Rhianna Wisniewski Perrine Royole-Degieux, IN2P3 Web Design Stanford Linear Accelerator Yuri Ryabov, IHEP Protvino Karen Acklin Center, funded by the Copy Editor Yves Sacquin, CEA-Saclay Alex Tarasiewicz US Department of Energy Melinda Lee Kendra Snyder, BNL Office of Science. Web Programmer Interns Boris Starchenko, JINR Mike Acklin Haley Bridger Maury Tigner, LEPP Lizzie Buchen Ute Wilhelmsen, DESY Photographic Services Amber Dance Tongzhou Xu, IHEP Beijing Fermilab Visual Media symmetry Gabby Zegers, NIKHEF Services 2 commentary: lyn evans multipole corrector magnets made in India, and support structures from Pakistan. Collaboration of this kind has long been the norm in particle detectors, but the LHC is the first major particle accelerator to be built with substantial contributions from beyond the host laboratory. What has made this possible is the long history of collaboration among particle physics laboratories around the world. When CERN was founded in the 1950s, Brookhaven was probably the new European lab’s main competitor—and also its best friend. Both labs were building new machines. A development at Brookhaven opened the road to higher ener- gies, an advance that Brookhaven immediately shared with CERN. As a result, CERN could build the proton synchrotron as a 28 GeV machine instead of a 10 GeV machine and briefly hold the world energy record before Brookhaven switched on the Alternating Gradient Synchrotron. In my younger days, I spent many hours in the control room of Fermilab’s Tevatron, always dur- Photo: Reidar Hahn, Fermilab ing those beautiful Chicago months of January and February when the CERN machines were shut down for maintenance. The experience I A truly international gained there on the world’s first superconducting accelerator synchrotron served me well in later years. Every time I take visitors to see the Large Hadron For our part, CERN has never hesitated to Collider, I’m reminded of the extent of the inter- share the results of our own accelerator innovation. national collaboration that has made this project Inviting partner labs to join in the construction of possible. Although the majority of the LHC was the LHC was a natural next step in this long tradi- produced in Europe through collaboration between tion of cooperation. CERN and industry, a walk through the acceler- We at CERN are all looking forward to switch- ator tunnel tells an international story. ing on the LHC in 2008, an event that will be The 27-kilometer-long LHC consists of eight closely tracked in the United States via Fermilab’s arcs joined by straight sections. These straight Remote Operations Center. That event will launch sections, each about 200 meters long, highlight the next level of our global collaboration: a new era the contributions from nations that are not CERN of discovery at the high-energy frontier. member states. Entering the tunnel at access point 1 next to the ATLAS experiment, for example, Lyn Evans is the LHC project leader at CERN. the first thing you see are the Japanese and American flags on the final-focusing inner-triplet magnets. The magnets are powered through a feed box made at the Lawrence Berkeley National Laboratory in California and are sitting on preci- sion jacks from India. Next come six magnets made in Novosibirsk, Russia. They bring the beam trajectories together for collision. A little farther on, there’s a neutron absorber from Berkeley and a superconducting magnet from Brookhaven National Laboratory in New York symmetry | volume 04 issue 10 december 07 that puts the beams on parallel trajectories.