Small is beautiful - the COSY compact synchrotron light source being developed at BESSY in Berlin has a circumference of less than 10 metres.

The Pauli Exclusion Principle stops more nucleons being added to an already full nuclear shell. Ho­ wever a distinguishable lambda is able to fit in anywhere. A beautiful and regular spectroscopic ladder can be seen with the lambda in successive levels. In E 798, positive incoming pions of momentum 1050 MeV were measured in coincidence with outgoing positive kaons, using the Moby Dick spectrometer at the LESB-1 beamline and a series of eight targets - beryllium 9, carbon 12, carbon 13, oxygen 16, silicon 28, calcium 40, vanadium 51 and yttrium 89. For the lighter targets the observed spectra were similar to those previously obtained in ex­ periments using negative kaon beams. For the heavier targets, the low-lying bound hypernuclear sta­ tes, including the ground state, were observed for the first time. In principle the two non-strange technik (IMT) in Berlin using vacu­ quarks in the lambda should lead to BESSY um ultra-violet synchrotron radi­ a 'Pauli pressure' due to effects COSY commissioning ation from the BESSY 800 MeV (anti-symmetrization) at the quark storage ring. As an integral part of evel, shifting the lambda spacings a submicron pilot processing line from the predictions of the simple In November the compact electron for X-ray lithography, IMT has con­ potential model. However this is storage ring COSY, a dedicated tracted the development of an ad­ not evident from the data. synchrotron light source for X-ray vanced compact light source to Higher energy resolution measu­ lithography under development at BESSY. At least five similar pro­ rements on nuclei with mass num­ the BESSY synchrotron radiation jects are underway elsewhere. ber greater than 100 could probe Laboratory in Berlin, passed an im­ Starting in 1984 with a feasibility the subtle quark effects in hypernu- portant milestone with electron study, the BESSY machine group clei. currents up to 75 mA stored at 50 worked out the present COSY de­ These experiments with pion MeV injection energy using normal sign for a critical wavelength of 1.2 beams have revived interest in hea­ conducting dipole magnets. Now nm at 600 MeV based on two su­ vy hypernuclei. Lambda particles the next step - to fit superconduct­ perconducting 180 degree dipoles should shrink the nuclear core, mo­ ing dipoles and increase the energy and four normal conducting quadru- difying its vibrational and rotational - can be attacked with confidence. pole magnets with a total circum­ frequencies. Other insights would The development of the COSY ference of only 9.6 m. follow from improvements in the machine results from the need for The compactness has some in­ experimental techniques. compact high intensity soft X-ray herent risks because of the need to E 798 included scientists from sources for sub-micron technolog­ inject electrons at low energies. It Brookhaven, Los Alamos, Houston, ies in highly integrated electronics. also requires the development of Tohoku, TRIUMF, Vassar, Carne­ These techniques have been stu­ superconducting 180 degree dipole gie-Mellon, Florida State, and Mis­ died for several years at the Fraun- magnets (4.5 T) with a very small sissippi. hofer Institut fuer Mikrostruktur- bending radius (0.44 m).

CERN Courier, January/February 1988 23 Quality from SEDEME <^

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24 CERN Courier, January/February 1988 Up-to-now more than 100 volumes compounds, luminescence, VI Astronomy, Astrophysics, and of Landolt-Bornstein - New Series, molecular acoustics, etc.... Space Research: Solar system, stars, Numerical Data and Functional interstellar matter, etc III Crystal and Solid State Physics: Relationships in Science and Crystal structure data of elements VII Biophysics: Technology, have been published. and compounds. Elastic, dielectric, Nucleic acids (in preparation). The volumes of the New Series are and optical properties. Ferro- and arranged into 7 subject groups. antiferroelectric substances. Mag­ N. B. A comprehensive index for the The topics covered are: netic oxides. Electron and phonon 6th Edition and the New Series is I Nuclear and Particle Physics: states, transport and magnetic prop­ now available. The index covers all Energy levels, radii, decay, reactions erties of metals. Physical properties volumes available until the end of nuclei. Angular correlations. of semiconductors, etc of 1985. Properties, production, scattering of IV Macroscopic and Technical Prop­ A detailed survey of all published elementary particles, etc.... erties of Matter: Thermodynamic volumes, New Series and 6th Edition, II Atomic and Molecular Physics: properties of liquid systems. High is provided in the new Landolt- Structure and molecular constants of pressure properties of matter, etc Bornstein Complete Catalog 1987. free molecules, magnetic properties Please write for your free copy to: V Geophysics and Space Research: of free radicals and of coordination Physical properties of rocks, Springer-Verlag and organometallic transition metal geophysics. Oceanography. 4005-Marketing, Heidelberger Platz 3 Meteorology. D-1000 Berlin 33

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CERN Courier, January/February 1988 25 The Bonn 500 MeV electron synchrotron, the first accelerator in Europe to use the strong focusing technique, started operating in 1958. It is to be moved to the Deutsches Museum in Munich.

With the present set-up, using two normal conducting dipoles prior to the installation of the su­ perconducting magnets, the injec­ tion process has been studied in detail. Electrons from a 50 MeV ra­ cetrack microtron, constructed by Scanditronix in Sweden, are in­ jected vertically by a pulsed sep­ tum and three kicker magnets. So far, maximum currents of 75 mA have been accumulated in three minutes. The next challenge is to store el­ ectrons with the superconducting dipoles. These magnets, built by Siemens/lnteratom, have already reached at the manufacturers the design field of 4.5 T and ramped at 1.2 T/min. The first electrons stored at final energy are expected in 1988.

removed to liberate space for 2 GeV it serves as a storage ring, BONN ELSA. The 'Deutsches Museum' stretching the pulsed beam to a in Munich will preserve this unique continuous one to give a duty cycle Continuous electron machine as a milestone of the Eu­ of nearly 100%. The energy loss beams from ELSA ropean accelerator development. by synchrotron radiation is com­ The second accelerator, the pensated by a single 500 MHz 2.5 GeV electron synchrotron, resonator (DORIS-type). In the sec­ In October the new Bonn Electron- came into operation in 1967. The ond mode, the magnets can be Stretcher-Accelerator, ELSA, was scientific programme at the accel­ ramped to a flat top field corre­ inaugurated by the Minister of erators was devoted mainly to sponding to 3.5 GeV. Two 5-cell Science and Research of North- studies of the structure of the nu- 500 MHz resonators (PETRA-type) Rhine Westfalia, Frau Anke Brunn. cleons and light nuclei, photo-in­ are then needed. Depending on The Federal Government was re­ duced production of mesons and the length of the flat top and the presented by P. Dallinger and baryons, new quark systems (di- time for injection, the duty cycle J. Rembser. The accelerator baryons) and the development of is between 6% and 95%. The and the three main experiments new experimental techniques (such beam current can reach SAPHIR, PHOENICS and the Elec­ as the use of polarized electrons, 0.5 microamps. tron Scattering Facility were pre­ photons and targets to study spin Tests with ELSA started last sented at a symposium. dependent effects). Since 1962 spring at 1 GeV and no major diffi­ ELSA is the third electron ma­ synchrotron radiation experiments, culties were encountered. The first chine built at the Physikalisches covering the vacuum ultraviolet external beam was achieved in Institut in Bonn with strong student and the X-ray region were per­ September and the ramping up to participation. The 500 MeV elec­ formed with both machines. 2 GeV worked well. 3.5 GeV oper­ tron accelerator, the first in Europe ELSA is a separated function ation is scheduled for this spring. with strong focusing magnets, machine, using the 2.5 GeV elec­ The physics will concentrate on started operation in 1958. After tron synchrotron as injector. It can photo-induced reactions on nu- more than 100 000 hours it was be operated in two modes. Up to cleons and light nuclei with two

26 CERN Courier, January/February 1988