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   The Layout of BEPC

 1.2. 1st. I.R. Experiment hall    

 3.Power Station of ring mag. and computer center  

 4.RF Station   5. 2nd  I.R. Experiment hall   

 6.Tunnel of storage  7.Tunnel of Trans. line  

 8.Tunnel of Linac   9.Klystron gallery      

 10.Nuclear physics Experiment hall       
 11.Power station of transport line 

 12.East hall for S.R. experiment 

 13.West hall for S.R. experiment   

 14.Computer center   

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   A Bird's Eye View of BEPC

     The Institute of High Energy Physics, Chinese Academy of Sciences completed the construction of the Beijing Electron Positron Collider ( BEPC ) which quietly nestles to the east of the BaBao Hills with a total floor space of more than 50,000 square meters.

   The purpose of building BEPC is mainly to carry out the research on charm and Tau lepton physics, the applied research on synchrotron radiation as well as mid-energy nuclear physics.

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   An Exterior View of BEPC

    BEPC started to run in early 1989 with part of its time devoted to the work in the energy region of J/psi. Up until November 1991, ten million J/psi events have been collected for d ata analysis.

    From November 1, 1991 to January 20, 1992, Tau Mass was measured accurately.  

  When the storage ring of BEPC operated at 2 GeV in its dedicated mode for synchrotron radiation, the beam performances reached the designed requirements.

    Now the shaping of a National Laboratory which will be open to both home and abroad is on the pipeline.

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   Trajectory of Electrons and Positrons in BEPC

   The contour of BEPC is quite like a giant badminton racket. The 200 meters long injector can accelerate electron and positron beams to 1.1 to 1.4 GeV which are to be transported to the in jection point of the storage ring via the eastern and western transport lines. There are two interaction points separately on the north and south of the storage ring, but currently only on the interaction point on the south of the storage ring is the large detector, namely the Bejing Spectrometer, installed. 

   The Synchrotron Radiation Laboratory is flanking the east and west of the southern area of the storage ring. Seven beam lines are now extracted from the three synchrotron radiation front ends located at the outer flank of the storage ring. Nine experimental stations have been buite. Research in such fields as X-ray topography, X-fluorescence, EXAFS, diffuse scattering, small angle scattering, diffraction, photoemission spectroscopy, biology spectroscopy and lithography is being carried out.

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   Central Control Room for BEPC

   The central control room for BEPC consists of the colored monitor of the main frame computer, touch panels and program controlled knobs. All the parameters are connected with the main frame computer through various convertors and interfaces. It has rich software system which can transmit thousands of signals collected in real time to the data base at a rate of 2 to 3 times per second. Operators on duty in the central control room can readily get information on the changes of the parameters of the different components of the machine and exercise timely control.

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  1.1-1.4 GeV Injector-Electron Linac for Production and Acceleration of Electrons and Positrons

  The injector is a linear accelerator which is composed of 56 disk loaded wave guide accelerating sections of 3.05 meters long each and some focusing cells with a total length of 202 meters and can accelerate electrons and positrons to 1.1-1.4 GeV. The emission current of the nanosecond electron gun is 5 amperes. The beam intensity of electrons from the injector is 600 milliamperes while that of positrons is 9 milliamperes.

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   Positron Source

    The positron source which is located between the 7th and the 8th accelerating sections has a target bombarding energy of 150 MeV and collects positrons with its magnetic compressor system.

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   Klystrons and Modulators in Klystron Gallery

    Here is the microwave power source for the injector which is composed of 16 sets of high power klystrons and pulse modulator and 13 sets of energy doublers.

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   Local Control Room of Injector


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   Switchyard on Transport Line for Electrons and Positrons

    The transport line is composed of a shared section of 30 meters long and the eastern and western sections of 90 meters long each with the eastern section transporting electrons and the western section transporting positrons.

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  Injection Section of Transport Line

  The injection section ( about 22.8 meters ) of the transport line is a bending system on vertical direction. The altitude difference between the horizontal planes of the storage ring and the injector is about 3 meters.

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  Current Kicker at Injection Region of storage Ring

  The injection system of the storage ring is composed of three in-one current kickers Lambertson magnet with a width of 7 mm septum being installed on the injection point.

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  Arc Sections of Storage Ring

  The circumference of the storage ring is 240.4 meters with four arcs. The linear sections on the eastern and western sides are injection sections while those on the north and south are interaction regions. Here installed are 44 bending magnets, 68 focusing magnets, 36 sextupole magnets, more than 30 other correction magnets and various of kinds of beam monitors and vacuum chambers and interfaces.

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  RF cavity in Storage Ring

  There is a RF station on either side of the northern interaction region. The RF cavity which acts on the passing beams is the accelerating station of the electron and positron beams. Its working frequency is 200 megahertz.

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  Power Supply Hall for Magnets of Storage Ring

  There are altogether 200 pieces of various kinds of magnets in the storage ring. The total power of the magnet power supply system is 2.5 MW with a current stability of 1*10-4.

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  Beijing Spectrometer

  The Beijing Spectrometer which is now being installed on the southern interaction point of the storage ring is more than 500 tons in weight, 6 meters in length, 7 meters in width and height. The central drift chamber, main drift chamber, shower counter and time of flight counter are installed in the solenoid magnetic field of 4000 Gauss. Surrounding the spectrometer is the muon detector.

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  Schematic Diagram A of the Beijing Spectrometer 

( BES-Particle Detector )


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    Schematic Diagram A of the Beijing Spectrometer 

( BES-Particle Detector )

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  Main Drift Chamber in Stringing Wires

   Both the length and the diameter of the cylinder of the main drift chamber are 2.3 meters. The cylinder which is used to give position parameters of the injecting particles contains more than 20,000 metal wires in 40 layers.

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  Shower Counter in Installation

   The shower counter is divided into the barrel part and the end part. The barrel part of the shower counter is composed of 24 layers of wire chambers between which there are lead plates, and there altogether more than 20,000 wire chamber units. The purpose of the shower counter is to measure the energy of the charged or neutral particles.

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  Installation of Time of Flight Counter and Main Drift Chamber

   Outside the main drift chamber is the time of flight counter consisting of a large area of plastic scintillators which is used to record the charged particles and calculate their speed with the time difference of the scintillators.

   Beijing Spectrometer Moved into Interaction Region

   In April 1989, the Beijing Spectrometer was moved into the interaction region. In our design for the Beijing Spectrometer, we absorbed the characteristics of MARK III with improved performances such as the upgrading of the solid angle coverage, energy resolution and position resolution.

   Electronic System of Beijing Spectrometer

    This is the counter hall where the data on the secondary particles obtained through the detector enters the nanosecond electronic system consisting of dozens of thousand signal channels for event selection and processing.

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   Control Room of Beijing Spectrometer

   Tracks of the particles from the detectors are shown on the screen of the control console of the spectrometer where data recording and on-line analysis of the detected particles are performed.  

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   The maximum likelihood as a function for t mass and detecting efficiency

   In the mt experiment of BES, the data taking, dated from November 1st of 1991 to January 20th of 1992, was done on the Beijing Spectrometer(BES). The measuring precision is 5 to 7 times as much as all the results ever obtained before.

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   Projection of the maximum likelihood to the plane of t mass and detecting efficiency



  Front End of Synchrotron Radiation Wiggler Beam Lines

   This is the front end of the synchrotron radiation beam lines 4W1A and 4W1B extracted from the wiggler in the IV Region of the storage ring on these Beamlines application research of hard X ray will be carried out.


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  Synchrotron Radiation Experimental East Hall

   It includes 5 beamlines. Beamlines 4W1A、4W1B and 4W1C which is Branched off the 4W1 wiggler, are applied to the studies of topography, EXAFS, diffuse scatter etc. Beamlines 4B9A and 4B9B, which are extracted from the bending magnet 4B9, are focusing and monochromatic beamlines for the studies of Diffraction, Small Angle Scattering, Photoemission Spectrometer and others.  

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  Topography Station

   With white X-ray from beamline ( 4W1A ), experiments on defects in single crystals, phase transition in crystals under applied temperature and static electric field etc., have been performed at this station.

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  EXAFS Station

   The unfocused monochromatic X-ray from beamline 4W1B is applied to the study of Extended X-ray Absorption Fine Structure in the station.

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  Diffuse Scattering Station 

   It is used for Huang scattering, the measurement of crystal character and phase structure and the study of phase transition.

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   4W1C Beamline

    Beamline 4W1C is a time-shared branch with beamline 4W1B, it is designed for the Diffuse Scattering Station.

   Diffraction Station

    A focused monochromatic radiation provided by 4B9A is used for the studies of material sciences and biology protein crystallography.


   Small Angle Scattering Station

    The research with this station is directed on the static and dynamic structure phase composition phase transition, distributions of defect in various fields such as molecular biology material science, physics polymer chemistry.


   Photoemission Spectroscopy Station

    The soft X-ray and VUV from the 4B9B beamline are applied to surface science studies in the station.

  Synchrotron Radiation Experimental West Hall

   There are two beamline here. Extracted from bending magnet 3B1, beamline 3B1A are used for the studies of lithography and biology spectroscopy.

  Main Computer Hall of Computing Center

   The scale of the computing center is equal to that of 15 VAX 11/780 computers. To cater for the physics research, it is used to analyze and process the data recorded in magnetic tapes. We have currently established communication networks with many high energy physics research institutions concerned.

  General Layout of Beijing Proton Linac Facility

   The Beijing Proton Linac and its application facilities consisted of the 35 MeV proton linac, research facilities for the treatment of cancer with fast neutrons, facilities for the production of short-life isotopes for medical applications and the experimental facilities for the positron emission tomography were completed and put into operation in 1998.

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  35 MeV Beijing Proton Linac

   The output energy of the Beijing Proton Linac is 35 MeV with a beam intensity of 60 milliampere. The energy of neutrons produced after bombarding target is about 20 MeV.

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  The Yangbajing Cosmic Ray Observatory


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  Scientific Balloon


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  30 MeV Electron Linac for Research of Free Electron Laser

    To carry out the research and application of free electron laser, we started to do research on and fabricate the high performance electron linac in 1986. This is a 30 MeV electron linac which can be used to carry out research on the free electron laser in IR region and provide application.

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  The first Fast Neutron Radiotherapy Facility China

   This facility has been used for treating patients since November 1991. The clinical treatment shows that the fast neutron radiotherapy is effective to certain cancers. With this facility, a lot of research works on several fields could be done, such as neutron radiation effect research etc.


Institute of High Energy Physics Chinese Academy of Sciences    07-08-22 14:22:19