collider opening up a new range of J. Bosser, L. Burnod, R. Coisson, numbers of protons to be delivered energy and with the intermediate E. d'Amico, A. Hof mann and J. Mann to experiments. At the beginning of bosons of weak interactions looming to be published in Nuclear Instru­ the year, operation changed from a on the horizon, the filmmakers could ments and Methods. three-week cycle to a weekly cycle. also find themselves in on one of the In this mode, the accelerator has biggest scientific discoveries of the operated with a 7.5 s cycle and Century. 1 s flat-top to give the average of FERMILAB 1018 protons per week from the Operation successes beginning of February through the Synchrotron radiation first week in March when a two from protons A major reliability campaign is under month shutdown began. way at Fermilab and since 1 Fe­ At the beginning of the shutdown In the September issue of 1978 bruary the accelerator has averaged an eighty hour period was devoted to (page 294) we reported the first ever 1018 protons per week. A new single studying accelerator operation at observation of synchrotron radiation pulse intensity record of 2.7 x 1013 450 GeV. The machine was off for from an orbiting proton beam in the protons was set on 21 February. only ten hours due to equipment SPS. Though the proton mass and These impressive records result problems almost entirely unrelated energy (even in the SPS and Fermi­ from a combination of a seven to the increased energy. For the lab machines) indicate negligible second duty cycle resulting from 450 GeV run the beam intensity radiation according to classical theo­ 350 GeV operation, high reliability reached 2.1 x1013 protons per ry, R. Coisson deduced that effects and high injection intensity. pulse. Consideration is now being could be seen at field discontinuities, Recently, Russ Huson, Head of the given to some operation at energies such as at the edge of a magnet. This Accelerator, has subdivided the Divi­ above 400 GeV in the near future. was shown to be true in the first sion into three parts. One group, For some time, the beam intensity qualitative experiments at CERN last headed by Rolland Johnson, is provided to the experiments has August which saw a radiation spot concerned with the 400 GeV pro­ been principally limited by beam on a TV screen, at energies above gramme. Rich Orr is in charge of instabilities during resonant extrac­ 350 GeV and intensities above another group handling installation tion which result in uncomfortable 6 x 1012 protons per pulse, increas­ of the Tevatron. Don Young heads levels of radioactivity in the transfer ing with energy and intensity. the third group studying accelerator hall. The understanding and cure of Since then the observations have aspects of colliding beam physics this limitation continues to have the been refined. Synchrotron light has (including the operation of the new highest priority of the conventional been detected at intensities as low 200 MeV cooling ring). accelerator programme. as 1011 and it has been shown that The 400 GeV programme group Another serious limitation is fund­ the light has a 23 |is amplitude has to satisfy the goals of the high ing constraints on the power bill. modulation corresponding to the energy physics programme regard­ Operation of the machine is now beam structure. In addition, the light ing operation of the present acceler­ normally keyed to the reduced cost is highly horizontally polarized as ator; it includes the Linac, (headed by of electricity at night and on week­ expected of synchrotron radiation. Curt Owen), Booster (Chuck Anken- ends. Thus, typically, the average The quantitative measurements, brandt). Main Ring (Frank Turkot), power used in the main ring changes using a photomultiplier, on the varia­ External Beams (Roger Dixon) and from 47 MW to 30 MW on week­ tions of the radiation with the char­ Operations (Jim MacLachlan and day mornings and back again in the acteristics of the proton beam, are in Jeff Gannon). evening. Operation in this mode has agreement with the theory. From mid-November last year to an impact on reliability. Work is in These observations are encourag­ mid-March the accelerator has oper­ progress to facilitate the day-night ing for the proton-antiproton pro­ ated at 350 GeV for certain neutrino changeover and diminish the pertur­ jects which could use synchrotron experiments needing lower muon bations on operations. For 350 GeV radiation at magnet edges for profile backgrounds. The lower energy there is essentially no change in the measurements on the two orbiting operation has also allowed a short day-night power level because of the beams. More detailed information cycle time. This, combined with reduced operating power required. will appear in a paper by R. Bossart, higher reliability, has allowed record There have been notable accom-

CERN Courier, May 1979 1 1 1 The resurrected magnets of the Brookhaven Cosmotron in use for a muon experiment at Fermilab.

(Photo Fermilab)

plishments In the Linac and Booster Old accelerators studying muon pairs of high invariant in the past year also, including the mass including upsilon, other heavy implementation and development of never die resonances and the di-muon con­ negative hydrogen ion injection into tinuum. The experiment will be fed the Booster. One feature of the technology asso­ by an intense pion beam with 109 to The ion source has turned out to ciated with high energy physics is 1010 negative pions per pulse in the be extremely reliable with an output the re-use of the magnets of retired High Intensity Laboratory. Muons of 50 to 60 mA. It also provides accelerators in the form of magnetic will be identified and their momenta great flexibility for the needs of the spectrometers. Examples include measured as they pass through the Cancer Therapy Facility and the the Chicago cyclotron magnet being octagonal shaped iron yokes of the electron cooling ring. used in the Muon Laboratory at Cosmotron magnets. At the Booster end of the Linac, Fermilab and the yoke of the Carne­ The pole pieces of the old acceler­ the ions are stripped in a carbon foil gie Mellon cyclotron which currently ator have been reshaped and plug­ which seems indestructible by the dominates intersection region 1-2 ged with iron in order to complete beam. This method of injecting by at the CERN ISR. The latest example the toroid. Five toroids are to be charge exchange allows virtually any is the first synchrotron magnet to be used; each 1.5 m thick, 2.4 m in number of protons to be injected into used in this manner — the magnet diameter. In addition, two smaller the best phase space of the Booster. from the Cosmotron, which oper­ toroids and a hadron absorbing wall Other improvements to the Booster ated in its previous incarnation as a make a total thickness of over 11 m combined with negative ion injection 3 GeV accelerator at Brookhaven of iron. have produced the intensity record which began operation in 1952. Particle trajectories are measured of 3 x 1012 ppp. This, in turn, cor­ The Cosmotron magnets are being with seven planes of drift chambers, responds to a potential of 3.9 x installed as elements of a toroidal one after each toroid. The old 1013 protons which could be in­ muon spectrometer by members of vacuum chamber gap in the Cosmo­ jected into the Main Ring. a Chicago-Princeton collaboration tron has been a particularly con-

112 CERN Courier, May 1979 venient feature permitting easy coil of accelerator, peak proton current, case in the storage ring at Los installation. Non-interacting beam the proton beam time structure Alamos. and much of the unwanted hadrons (affecting the usable time-of-flight The three meson factories use the produced in the target pass un­ range for neutrons), and the neutron primary beam stop as a neutron observed through the apparatus. The intensity and spectrum. source. The beam stop facility is gap has also facilitated the installa­ The proton source may be an highly developed at SIN and tion of a small, iron-free passage for existing accelerator, as with the TRIUMF. The principal use of the precision observation of particles meson factories LAMPF, SIN and beam stop area at LAMPF is for produced at 90° in the centre of TRIUMF — or an existing booster radiation damage experiments. The mass. synchrotron as at Argonne and KEK. WNR facility at LAMPF has two New accelerators are planned at large stations and is designed for LOS ALAMOS Rutherford and Karlsruhe. 20 |ia. An upgrade is planned to The KEK neutron source KENS, permit 100 jia operation in conjunc­ Meeting on neutron described by M. Sasaki, will use the tion with a storage ring which is now sources existing 500 MeV booster machine being designed. to deliver 6 x 1011 protons per pulse Among the laboratories with oper­ Accelerator technology has devel­ at an effective average of 1 5 pulses ating experience is Argonne with the oped beyond particle and nuclear per s, time-shared with beam Zing-P' test bed. N. Swanson des­ physics to cover newer research headed for injection into the 12 GeV cribed work on targets and instru­ areas — solid state and atomic accelerator. mentation. The instrumentation de­ physics users of synchrotron radia­ The Rutherford project, reported veloped is on various neutron spec­ tion sources — muon beams for by J.T. Hyman, is an 800 MeV trometers and on provisions for muon spin rotation — biomedical 200 jia synchrotron concentric with proton and neutron radiography. users of electron, proton, heavy ion the decommissioned Nimrod ring. Swanson also drew attention to the and pion beams — and now nuclear The Argonne Booster II runs at reactor-like construction of the engineering materials science and 500 MeV delivering 8 x 1011 pro­ targeting facilities. other users of intense pulsed Spalla­ tons per pulse at 1 5 pulses per s. A All ring machines, including the tion Neutron Sources (SNS). high intensity synchrotron proposed LAMPF-WNR storage ring, use or The activities reported at the Inter­ for a later stage would deliver up to will use FT stripping injection. Thus national Collaboration on Advanced 500 jua. A 10 ma 500-1000 MeV intense FT source technology is an Neutron Sources meeting at Los linac is being considered by a important component of the design Alamos in March illustrate this Karlsruhe-Julich team. picture. Fast cycling machines with growth. This ICANS meeting was The Karlsruhe accelerator would 1 5 pulses per s minimum are the rule the third in a series which appears to deliver 5 Megawatts average beam for pulsed neutron sources. This is a be becoming a regular feature in this power. J.C. Vetter reported that a challenge for the synchrotron de­ vigorous new field. pair of sector-focused cyclotrons is a signs. The 50 Hz Rutherford syn­ SNS representatives came from design alternative to the linac. How­ chrotron must use a non-conductive Canada, the UK, Japan, Switzerland, ever with 100 ma pulsed current, the beam tube to eliminate eddy cur­ Germany and the US to share infor­ linac may be the safer design. The rents from the magnet ramp. mation on designs for accelerator- beam loading factor would be high, A more speculative field is electro- based neutron sources. Some facili­ so it would take little more r.f. to nuclear fuel enrichment, a possible ties are in the early stages of opera­ power a linac in comparison with project discussed by J. Fraser from tion while others are in various cyclotron. the Canadian Chalk River National stages of design or construction. The target design work, described Laboratory. Los Alamos has made a The typical SNS facility consists of by G.S. Bauer, is the responsibility of systems study of an enrichment a 500-1000 MeV proton accelera­ the Julich team. Target power den­ facility. tor, a target station which is both sities obviously exceed anything Each medium-energy beam pro­ beam stop and neutron moderator, experienced at present. A storage ton yields 20-30 spallation neu­ and neutron flight tubes and spec­ ring at the end of the Karlsruhe linac trons. Typical thermal neutron fluxes trometer systems. Among the im­ is being considered for changing available at the experimenter's end portant design options are the type pulse lengths and rates, as is the of the beam pipe are 1014 neutrons

CERN Courier, May 1979 113