INTERNATIONAL JOURNAL OF HIGH-ENERGY PHYSICS 1 PowerMod™ The Power You Need sm High Voltage.Solid-State Modulators At Diversified Technologies, we manufacture leading-edge solid state, high power modulators from our patented, modular design. PowerMod™ systems can meet your pulsed power needs - at up to 200 kV, with peak currents up to 2000 A. V PowerMod*™ HVPM 100-300 30 MWModulator (36" x 48" x 60") PowerMod™ HVPM 20-150 Pulse: 20 kV, 100A, ljis/div PowerMod™ Modulators deliver the superior benefits of solid state technology including: • Very high operating efficiencies • < 3V/kV voltage drop accross the switch PowerMod™ HVPM 20-300 6 MW Modulator (19" x 30" x 24") • <1mA leakage • Arbitrary pusewidths from less than 1 jus to DC • PRFsto30kHz • Opening and closing operation Call us or visit our website today to learn more about the PowerMod™ line of solid-state high power systems. DIVERSIFIED TECHNOLOGIES, INC. 35 Wiggins Avenue Bedford, MA 01730 781-275-9444 www. d i vt ecs.com PowerMod*™ HVPM 2.5-150 3 75 KW Modulator (19" x 19.5" x 8.5") D 1999 Diversified Technologies, Inc. PowerMod™ is a trademark of Diversified Technologies, Inc. Contents Covering current developments in high- energy physics and related fields worldwide CERN Courier is distributed to Member State governments, institutes and laboratories affiliated with CERN, and to their personnel. It is published monthly except January and August, in English and French editions. The views expressed are not necessar­ ily those of the CERN management. CERN Editor: Gordon Fraser CERN, 1211 Geneva 23, Switzerland E-mail [email protected] Fax +41 (22) 782 1906 Web http://www.cerncourier.com COURIER Advisory Board VOLUME 39 NUMBER 5 JUNE 1999 R Landua (Chairman): F Close, E Lillest0l, H Hoffmann, C Johnson, K Potter, PSphicas Laboratory correspondents Argonne National Laboratory (USA): D Ayres Brookhaven, National Laboratory (USA): PYamin Cornell University (USA): D G Cassel DESY Laboratory (Germany): Ilka Flegel, P Waloschek Fermi National Accelerator Laboratory (USA): Judy Jackson GSI Darmstadt (Germany): G Siegert INFN (Italy): A Pascolini IHEP, Beijing (China): Qi Nading Jefferson Laboratory (USA): S Corneliussen JINR Dubna (Russia): B Starchenko KEK National Laboratory (Japan): A Maki Lawrence Berkeley Laboratory (USA): B Feinberg Los Alamos National Laboratory (USA): C Hoffmann Chameleon complex pll Chasing CP violation p22 AMS results p7 NIKHEF Laboratory (Netherlands): Margriet van der Heijden Novosibirsk Institute (Russia): S Eidelman Orsay Laboratory (France): Anne-Marie Lutz Physicswatch 5 PSI Laboratory (Switzerland): P-R Kettle Rutherford Appleton Laboratory (UK): Jacky Hutchinson Saclay Laboratory (France): Elisabeth Locci News 6 IHEP, Serpukhov (Russia): Yu Ryabov Stanford Linear Accelerator Center (USA): M Riordan Space Shuttle experiment reveals unexplained particle behaviour. TRIUMF Laboratory (Canada): M K Craddock Major agreement made with China. DAFNEand KLOE's kaons. Produced for CERN by Institute of Physics Countering the beam-beam effect. Understanding deconfinement. Publishing Ltd I0P Publishing Ltd, Dirac House, Temple Back, Bristol BS16BE, UK Astrowatch ii Tel. +44 (0)117 929 7481 E-mail [email protected] Web http://www.iop.org Features Publishing director: Mark Ware The quintessence of cosmology 13 Publisher: Mark Wormald The universe's expanse account Art director: Andrew Giaquinto Production controller: Kate Booth by Technical illustrator: Alison Tovey Searching for signals from the dark universe 17 Sales manager: Harvey Stockbridge Advertising manager: Jo Nicholas Intriguing result from new experiment looking for dark matter Classified sales: Chris Thomas Advertisement production: Katie Graham Product manager: So-Mui Cheung A tale of three regions 20 How CERN sits astride an international frontier Advertising: Jo Nicholas or Chris Thomas Tel. +44 (0)117 930 1026 E-mail [email protected] In hot pursuit of CP violation 22 Fax +44 (0)117 930 1178 Looking for CP violation in new settings General distribution Jacques Dallemagne, CERN, 1211 Geneva 23, Switzerland. E-mail [email protected] Meetings highlight boom in accelerator developments 26 In certain countries, to request copies or to make address changes, contact: News and trends from international accelerator meetings China: Chen Huaiwei, Institute of High Energy Physics, P.O. Box 918, Beijing, People's Republic of China Neutrinos with a swing Germany: Gabriela Heessel or Astrid Nagel, DESY, Notkestr. 85, 32 22603 Hamburg 52 A useful neutrino analogy Italy: Mrs Pieri or Mrs Montanari, INFN, Casella Postale 56, 00044 Frascati, Roma United Kingdom: Su Lockley, Rutherford Appleton Laboratory, Recruitment 34 Chilton, Didcot, Oxfordshire 0X11OQX USA/Canada: Janice Voss, Creative Mailing Services, P.O. Box 1147, St Charles, Illinois 60174. Tel. 630-377-1589. Fax 630-377-1569 People 40 Published by: European Laboratory for Particle Physics, CERN, 1211 Geneva 23, Switzerland. Tel. +41 (22) 767 6111 Bookshelf 41 Telefax +41 (22) 767 65 55 USA: Controlled Circulation Periodicals postage paid at St Charles, Illinois Printed by: Warners (Midlands) pic, Bourne, Lines, UK Cover: Glittering stars and wisps of gas create a breathtaking backdrop for the self-destruction of a massive star, supernova 1987A, in the Large Magellanic Cloud, a nearby galaxy. This supernova was © 1999 CERN a turning point in the study of these cosmic explosions. For the latest implications of these studies ISSN 0304-288X see pl3. In this NASA Hubble Space Telescope image, the supernova remnant is surrounded by a forest of ethereal, diffuse clouds of gas. This three-colour image is composed of several recent pictures of the supernova and its neighbouring region. In a few years the supernova's fast-moving material will produce a new series of cosmic fireworks that will offer a striking view for more than a decade, (photo: Hubble Heritage Team.) CERN Courier June 1999 3 11 M§ 1ffl MIMsl 1 il ilBliMBBlBDHIlK^iVJ IM il i'lM ll MS f 1 1 Iff I II* i il» i>t i* t ii\ sit! » i! H i Vf*'. fit* > ,*? I fiTO*] fR*l I Fil T^jfil i w * t'i . Jffl 11[• f M iWi 1 Mil QgMHBKffll Pftl <] •] tsM* i i •• *•«.*•"*« i . Fujikura pure Si (71 m) J . Spectral Ge-doped (90m) 1 l/t«/lMffiH?3 Loss»(-0.96 ± 0.08).104dBm/MRad/m *4— Fibre LDC and DRIC —> F!uence = 0.0357 MRad/b I PhysicsWatch Edited by Alison Wright Except where otherwise stated, these news items are taken from the Institute of Physics Publishing's PhysicsWatch service, which is available at "http://PhysicsWeb.org". DNA acts like a semiconductor Scientists at Basel have demonstrated that (10~7 mbar), the ropes were broken using a the current with voltage, obeying Ohm's Law, DNA ca'n conduct electricity - a property that mechanical point.This was watched using a was measured in the ±20mV range.The DNA could lead to an effective way to repair a DNA low-energy electron point source microscope had a resistivity of about 1 M^/cm - equiva­ helix after radiation damage. (a coherent beam of 20-300 eV electrons), lent to that of a good semiconductor. DNA in water was dropped onto a gold- which produced holographic images. The details of the conduction mechanism coated carbon foil punctured with an array of The point was then used to create a poten­ are not understood, but the fact that DNA 2 (Lim holes. Blotting paper removed most of tial difference between the loose end of the chains of up to several tens of milimetres can the liquid, leaving ropes of DNA molecules DNA rope and the foil, to which the other end easily be made means that DNA is suited for spanning the holes in the foil. of the rope was attached. Current flowed use as quantum wires in mesoscopic devices Inside an ultrahigh vacuum chamber along the molecules and a linear variation of (largerthan 1 nm butsmallerthan 1 ^m). Is sonoluminescence solved? Laser makes antimatter Gas bubbles trapped in a liquid and excited by sound waves expand then collapse, emit­ Experiments with the Petawatt laser at ting an intense burst of light - a process Lawrence Livermore National Laboratory have known as sonoluminescence.Typically, a created antimatter - something that is usually bubble can expand by up to 50 |im before the preserve of high-energy physics. collapsing, usually within 50 LIS, to a radius of The laser (1 petawatt in a 1 fs pulse) was less than 1 Lim, but remain stable. focused on a thin gold disc, ripping electrons This had never been fully explained, but from the gold atoms and accelerating them to now a team of scientists from Harvard, several mega-electronvolts.The electrons col­ Marburg in Germany and Twente in the lided with other atoms, producing X-rays with Netherlands has proposed a model to explain enough energy to release neutrons and the bubble's stability and the light emission. induce fission in a sample of uranium metal. New features include the dependence of However, the researchers also observed the bubble's temperature on its radius and an positrons being created - more than 100 from allowance for the small emissivity of the a single laser shot and consistent with the weakly ionized noble gas inside the bubble expected rate of electron-positron pair pro­ (after recent experiments demonstrated that duction by X-rays. AIP all molecules other than noble gases diffuse from the bubble). The team has suggested that the light is In sonoluminescence, a gas bubble in a Atomic laser emitted by radiation from the ionized gas liquid-filled cell is excited using sound (thermal bremsstrahlung) and by the recom­ waves, causing it to expand before Several steps towards building an atomic bination of ions within the bubble. collapsing and emitting a visible flash. laser have been made by groups in the US, Japan, Israel and Germany.