The storage ring for the Beijing Synchrotron Radiation Facility(BSRF) is the 1.6-2.8 GeV Beijing Electron-Positron Collider(BEPC), which was constructed for China's first project on high energy physics research. The storage ring was designed to be operating either in the colliding mode or in the dedicated synchrotron radiation mode. The project was approved by the Chinese government at the end of 1983, and completed in 1989.
The Beijing Synchrotron Radiation laboratory(BSRL) was founded in July of 1985, and the construction of the first beam line was completedin 1989. The first phase construction of BSRF was finished in 1991, three beam ports, seven beam nine experimental stations were constructed. Since 1991 , BSRF has been opened to users from all over the country.
The discription of the beam lines and experimental stations and the present research activities is given in this paper. the second phase construction of BSRF as well as the plan of constructing a third generation new synchrotron radiation source, the Beijing Light Source(BSL), in adjacent to BSRF, are described.
Table 1. Main parameters of the BEPC electron linac.
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Electron energy 1.4-1.55 GeV
Pulsed electron current 2 A (for positron production)
0.2 A (for electron injection)
Pulse width 2.5 ns
Pulse repetition rate 50 s-1
Number of klystrons 16
Klystron power >= 20 MW
Number of accelerating tubes 56
Working frequency 2856 MHz
Energy spread *E/E 0.6%
Bunch phase spread 5.
Energy of preinjector 30 MeV
Bombarding energy for position150 MeV
prodution
Emittance of positron beam 0.22(MeV/c)/cm
Positron production rate 0.025 e+/e- GeV
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Table 2. Main parameters of the BEPC storage ring.
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Parasitic mode Dedicated mode
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Electron beam [GeV] 1.55 2.2
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Electron beam current [mA] 20 100(4 bunches)
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Number of intersecting regions 2
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Circulating frequency [MHz] 1.247 1.247
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Characteristic photon energy 0.8 (B) 2.28 (B)
[keV] 5.79 (W)
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Horizontal chromaticity Vx -11.4 -15.0
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Vertical chromaticity Vy -19.6 -8.2
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Momentum compaction factor a 0.042 0.014
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Hor.natural emittance [m.rad] 3.9*10-7 7.6*10-8
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Ver.natural emittance [m.rad] 3.9*10-8 7.6*10-9
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overall beam lifetime [hr] 6-10 (@1.55 6(@2.2 GeV)
GeV)
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Max.magnetic field [kG] 9.028 9.023
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Bending radius [m] 10.345 10.345
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Max.horizontal beta [m] 49.7 17.4
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Max.vertical beta [m] 71 15.4
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RF harmonic number 160 160
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frequency [MHz] 1.9953 1.9953
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peak voltage [kV] 2.0 MV
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Max.power [kW] 150
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Bunch per beam 1 1-160
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SR loss per turn [keV] 522
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SR loss per beam [kW] 34
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Longitudinal turn .021
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Rms energy spread [*E/E] 4.12*10-4 5.85*10-4
(@1.55 GeV) (@2.2 GeV)
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Rms bunch length [cm] 5.0 4.4
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Beam life time [hr] 7-8 7-8
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Peak brightness
[ph/mm2/mrad2/0.1% BW] 1.1*1011 7.0*1012
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BEPC storage ring contains:
! 40 bending magnets, from 30 of these magnets s
ynchrotron radiation can be extracted.
! four straight sections of the length of 3.1 m w
hich can accommodation insertion device.
! one long linear section of 5.1 m.
! four straight sections of the length of 2.9 m
left for the emittance control wigglers.
At present beam line are only extracted from the bending magnets and straight sections located in two (III and IV) of the four quadrants of the ring. (see figure 2)
Seven beamlines from three beam ports (two from bending magnets and one from a wiggler) have been constructed. The specifications of the beam lines and the corresponding experimental stations are given in table 3.
Table 3.Specification of the BSRF photon beamlines.
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Beamline 4W1A 4W1B 4W1C 4B9A 4B9B 3B1A 3B1B
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Range X X X X-SX VUV SX UV-VIS
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Hor.angular
acceptance 1 1 1 5.5 4.5 7.5 3
(mrad)
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Photon energy 3.5-22 keV 3.5-22 keV 3.5-22 keV 3-12 keV 10-1200 eV 4-20 A 1400-1500 A
/wavelength
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Mirrors none none bent bent torroidal cylindrical cylindrical
cylindrical cylindrical paraboloidal
ellipsoidal
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Monochro- crystal crystal bent crystal spherical multilayer plane
mator crystal grating grating
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Spot size 45*14 23.1*2.31 1.2*0.5 3.0*1.5 3.0*1.0 35*35 0.5*0.5
(mm2)
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Energy 2*10-4 4*10-4 2*10-4 1*10-3 4*10-3
resolution @12 keV @12 keV @8 KeV @200 eV
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Experi- Thopography EXAFS diffraction Diffrac- Photoelec- Lithography Biology
mental fluorescence Fluore- diffuse tion tron Soft X-ray spectroscopy
stations X-ray scence scatt. SAXS spectroscopy Application
Photoacoustics EXAFS
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BSRL Status and Future
BEPC National Laboratory (BEPCNL):
Linear Accelerator Laboratory
Storage ring Laboratory
Experimental High Energy Physics Laboratory
BSRL
Table 4. Number of executed proposal during 1991-1993
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year 1991 1992 1993
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Executed 53 46 54
Proposals
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Usually there are four shifts of dedicated SR operation mode of the ring BEPC each year around Febrary, June, September and January, each dedicated mode running lasts for 10-15 days.
The development of the BSRF consists in two aspects,one is to upgraded and to expand the existing facility, by improving some optical elements and designs, and constructing more beam lines and experimental stations.
Table 5. New facilities in the second phase
construction of BSRF.
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ID material # of poles peak mag. magn.gap[mm] K
field[T]
Nd-Fe-B 10 1.5 39 42
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BL photon energy focusing monochromators station
3W1A 3-30 keV N scanning fluorescence
high pressure diffraction
3W1B 50-1100 eV Y grating soft X-ray optical
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Planning for a new third generation synchrotron radiation facility. The new SR source is called the Beijing Light Source (BSL),
! It consists a race track storage ring, two long
straught section of the length of 16 m.
! The lattice is TBA configuration of 8 periods,
each period consisting of 3 bending magnets, one
of which is a superconducting magnets of length
of 0.3 m and magnetic field strength 4.7 T, the
bending radius is 26 m.
! There are 6 straight of the length of 6 m.
! The energy of the storage ring is designed to be
1.5-2.0 GeV.
! The emittance will be about 10 nm.rad ,and the
current will be 300 mA.