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IV. Accelerator Science and Technology
4.1 Injector
4.1.1 General Statistics and Schedule
In 1998, BEPC Injector provided 4080Hrs beam time to the Storage Ring which included beam energy at 1.55GeV The total operation efficiency is 98.1%. . Table 4.1.1.1 shows general statistics and Table 4.1.1.2 shows the operation time partition in 1998. Table 4.1.1.1
Operation Time Beam Time Miscarriage Operation Efficiency 231Days 170Days(120+50)
General Statistics
5544Hrs(Including Machine Study Time) 4080Hrs 79Hrs 98.1%
Table 4.1.1.2
Date 01/05~03/10 03/10~05/29 05/29~06/01 06/01~07/08
Operation Schedule
Injector Maximal Energy Storage Ring Injection Energy 1.72GeV 1.45~1.6GeV 1.76GeV 1.74~1.5GeV Summer Shutdown Linac Machine Study 1.3GeV (e+/e) 1.55GeV (e+/e) 1.3GeV (e)
11/05 ~12/17 12/17 ~12/31
1.4~1.6GeV 1.6~1.74GeV
1.3GeV (e) 1.3GeV (e+/e)
IV. Accelerator Science and Technology 37
4.1.2
Equipment’s Improvement
In the period of equipment summer shutdown, we had replaced eleven ion pumps and some other equipments. The replacements are listed in Table 4.1.2.1, in which one 65MW-Klystron was replaced in the spring. Table 4.1.2.1 Name Number
Ion Pump
List of the Replacements
65MW KLYSTRON
Magnet Power 30MW Supply KLYSTRON
11
28
2
1
4.1.3
Achievement of Medium Energy Radiation Accelerator
Based on a few years of works, in 1998 we rebuild a new modulator for the medium energy radiation accelerator. The modulator can work very well at 250PPS. The accelerator has been tested in 100Hz PPS. Table3 shows the main parameters of this accelerator. Table 4.1.3.1 Energy Pulse Current Avg. Current Pulse Width Repeating Frequency Avg. Power Avg. Dose Parameters of the Radiation Accelerator 10 MeV 500 MA 120 mA 2.5 uS 100 PPS 1.0 KW 1.5*105 RAD/H M
4.2 Storage Ring
4.2.1 Operation Statistics
1998 is the eleventh year of Beijing Electron-Positron Collider (BEPC) since its first operation in 1988. BEPC’s operation was started on March 10 this year, and was finished in July 8. The total operation time is about 2890hrs, among which the start-up for BEPC took up 10.8%, BES 27.3%, machine study 23.6%,
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synchrotron radiation 20.7% injection 10.9%, and faults 6.7%. Figure 4.2.1.1 gives the statistics of BEPC’98 operation.
Start-up 10.8% Injection 10.9%
Fault 6.7%
BES 27.3%
SR 20.7%
MD 23.6%
Figure4.2.1.1 The statistics of BEPC’98 operation.
4.2.2
4.2.2.1
Operation
R-Scan
One of the main tasks of this year is R-scan. We have performed for it from April 25 to May 26, at the center-of-mass energies of 3.2GeV, 3.4GeV 3.55GeV, , 4.6GeV 5.0GeV and 2.6GeV, totally six energy points. Table 4.2.2.1 gives some , typical machine parameters at different beam energies. Table 4.2.2.1 Typical collider parameters at different beam energies E (GeV) 3.2 3.55 4.6 5.0 2.6 Ie++Ie(mA) 29.1 30.0 26.6 21.6 19.6 L( ×1030 cm-2s-1) 3.4 2.7 2.4 2.8 1.3 τ (hrs) 4.3 7.8 7.8 6.5 7.0 S/N 158 40 42 17 133
IV. Accelerator Science and Technology 39
4.2.2.2 Machine Studies This year we have spent much time and put many efforts on machine studies. Table 4.2.2.2 lists some items. Table 4.2.2.2 Some experiments done in BEPC’98 operation • Single interaction point experiment • Multi-bunch scheme experiment • Photoelectron instability study • Beam-beam interaction • Beam response matrix • RF feedback experiment • 2.0 GeV collision • 1.55 GeV injection, and so on. 1) Single Interaction Point Experiment From accelerator physics, reducing the interaction points along the ring will increase the colliding beam currents. At present, BEPC is running with two interaction points, and with only one detector BES at the south interaction point. Single interaction point experiment separated the electron and positron beams at the north interaction point with a pair of electrostatic separators, so the total interaction points were reduced to one. After hard work, some progresses were achieved. At the J⁄ψ energy, with the β* = 7cm, the colliding beam currents y reached ∑I= 42.7mA, and the maximum luminosity reached 4.4×10 30 cm-2s-1, which is increased by a factor of 20%, compared to the maximum luminosity of two interaction points collision scheme with β* = 5cm in this time’s BEPC y operation. 2) Pretzel scheme experiment There is only one beam pipe in BEPC, in which the electron and positron beams are both contained. In order to realize multi-bunch collision, the electron and positron beams must be separated at all the parasitic interaction points. Pretzel scheme uses a pair of electrostatic separators to create different vertical closed orbits for electron and positron beams, and separates the two beams at all the parasitic interaction points. In our experiment, we used a pair of electrostatic separators near the south interaction point to create the different vertical closed
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orbits for electron and positron beams. Of course, since we were still short of another pair of electrostatic separators near the south interaction point for injection, multi-bunch collision couldn't be really achieved. We obtained multi-bunch injection of electron beam and 1×1 collision (one bunch electron and one bunch positron) at the J⁄ψ energy with β* = 5 cm was obtained. y
4.3 Control
4.3.1 Readback Improvement of Main Power Supplies in T.L.
We use SAM module for the readback system of the main power supplies in T.L., then main control parts, PSC modules, can be replace with PSC developed by us.
4.3.2
Remote Control Upgrade of Wiggler Magnet
The remote control for wiggler magnet was realized by DECNet protocol via Ethernet, client/server mode. In the client side, the program was written in assembly language. After we rewrote the program, and rewrote the server program using MOTIF, the system is running better.
4.3.3
Realization of Interlock System in Power Supply Station
The alarm system in the power supply station is the part of BEPC interlock system and has been running safely since November 1998.
4.3.4
Improvement of T. L. and Ring Vacuum Control System
The interlock of T.L. devices was completed using Programming Logic Controller (PLC) and connected to the central interlock system successfully. The upgrade of the Ring vacuum control system is undergoing and will be put in use in October 1999.
4.3.5 Upgrade of APS Power Supply Boxes in Local Control Stations 4.3.6 Application Software
(1) ramp program (2) table-ramp
IV. Accelerator Science and Technology 41
(3) (4) (5) (6) (7) (8)
“expert system” for automatic changing of RF extended saving buffers for Lattice modes displayed BEPC luminosity 4-bump several standardized programs were added for saving power upgraded standardized program of Lambson power supply
4.4 Beam Diagnostic Instrumentation System
4.4.1 Some problems have been solved
1) To shield the DCCT, reduce the EMI background of BES We have modified the DCCT by adding a shielding. This correction solved the EMI background of BES and made the BES operation possible under the conditions of the high collision beam currents. 2) To change injection mode, increase the beam lifetime on synchrotron radiation mode We found occasionally that to change the filling pattern could increase the beam lifetime from 8-10 hours to 20-30 hours. Thus, it was very important to ensure the machine to run successfully on synchrotron radiation mode in the end of 1998.
4.4.2
Experiments
1) Calibrating the DCCT, WC and BCT of Linac The DCCT, WC and BCT are calibrated to increase the reliability of the beam current measurements. 2) Calibrating the profile measurement system with synchrotron light The system was calibrated to make the absolute measurements of the transverse beam sizes and emittances. 3) Experiment of Beam based alignment Beam position monitors (BPM) are usually aligned with respect to the nominal beam orbit that goes through the center of the quadrupoles. The technology of beam based alignment (BBA) would improve the measurement accuracy of the BPM offset. We have performed the preliminary experiment of BBA. This work might gain the experience for the future studies.
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4) PEI Experimentation We have performed the fourth PEI experiment with KEK colleagues. 5) To monitor the synchrotron light position We have set up a measurement system of synchrotron light beam position and gathered plenty of long term beam position data during the dedicated SR-operation.
4.4.3
Upgrade of the BEPC Beam Instrumentation System
1) To establish database, to sample and display the main parameters of BEPC An Archives database system based on client/server model via TCP/IP has been established. The database is used to store many machine parameters, including the beam and device parameters. It could provide various services including data stores, queries, analysis and reports. Users such as specialists, machine operators and managers can get data from any computer via the network. 2) Upgrade of the synchrotron light monitoring system ( phase I ) We have made two optical tables and added a number of optical components into the system. All those upgrades have improved the stability and the reliability of the system.
4.5 Proton LINAC and Its Applications
4.5.1 Running and Improvement of the BPL
The BPL was operated normally for about 3000hrs in 1998. During the summer maintenance time, the power supply of ion source filament was improved in order to enhance the maximum supply current; the gas supply system of ion source was changed for improving the vacuum of pre-injector. At the same time, the high frequency system, the control system, the magnet power supply system, the water-cooling system, the vacuum system were examined and repaired. Therefore the reliability of the BPL is raised.
4.5.2
Fast Neutron Radiotherapy Research
The study of fast neutron radiotherapy made progress in 1998. The major contents are as follows: 4.5.2.1 Research on Neutron Radiophysics
IV. Accelerator Science and Technology 43
A lot of experiments and tests of neutron radiophysic had been done on the IHEP neutron radiotherapy facility: (1) P(35)Be neutron energy spectrum was measured with the activation method. The comparison between neutron energy spectrum in air and in water was made. (2) Neutron dose distribution measurements: Measurements of the Central Axis Depth Dose (CADD); Off-Axis Ratios (OAR) in air and in water phantom for differential fields. Acquired data are good enough for neutron clinical treatment. (3) Calibration of the neutron dose measurement instruments, the ionization chambers are sent to NIM (National Institute of Metrology) for calibration in their 60 Co beam. This Calibration is done once a year. (4) The experiments of Wedge filter have been done. The Wedge filter was made out of Teflon with an actual angle. It has been used in patient treatment to achieve more uniform distribution in any beam combinations. (5) The research of fast neutron dose response of “Tris” Lyoluminescence. 4.5.2.2 Research on Neutron Radiobiology:
(1) The research on Apoptosis response of nasopharyngeal carcinoma cell line (CNE-2) induced by neutron irradiation. (2) The research on fast neutron radiation -induced DNA double-strand breaks. (3) The research on neutron radiation sensitivity of four tumor cells (WM9839, KB, LS-T-117, PC3M) 4.5.2.3 Research on Fast Neutron Therapy Clinical Treatment:
The clinical treatment has been successfully made under the guidance of an expert group, whose members are from IHEP and some famous medical institutions and hospitals. 77 patients have been treated by neutron beam therapy during one year, the total number of the patients are 450 since November 1991. It is concluded that neutrons are efficacious for certain specific tumor types, such as parotidoscirrhus, prostate sarcoma, salivary gland sarcoma, pancreas cancer, melanocarcinoma, osteosarcoma, chondrosarcoma, synoviosarcoma, metastasis cancer of the head and neck, lung-metastasis etc.
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4.5.2.4 Improvements of the Neutron Therapy Facility: Many improvements have been made in the devices of the neutron therapy facility: (1) A neutron radiotherapy positioning devices for head and neck had been made. It is useful for treatment positioning of head and neck. (2) A neutron radiotherapy automatic control table had been made , It is used to control the movable treatment chair , which has X Y Z and rotational motions . (3) The improvements of the laser beam positioners had been made. It is used to verify position of patient in neutron radiotherapy treatment. (4) The computer programs for data of patient had been made. All of the neutron therapy facilities were maintained during summer maintenance period.
4.5.3
Research on Radio-isotope for Medicine
A new potential dopamine D3 receptor PET tracer, i.e. (R, S)-7-hydroxyl-2[N-(3’-allyl)-N-(3’-[18F]fluoropropyl)]aminotetralin ((R,S)-[18F]-7-OH-AFPAT) has been firstly designed and synthesized in our laboratory, and the animal test of this new D3 receptor ligand has also been carried out. The results from animal study suggest that (R, S)-[18F]-7-OH-AFPAT can penetrate the brain blood barrier (BBB) of Wistar rat, and the brain uptakes of this radiotracer were 1.12% and 0.52% (injected dose/brain) in 2 min and 30min respectively after in vivo injection of this tracer. From the regional distribution pattern of (R, S)-[18F]-7-OH-AFPAT in rat brain, we found that this tracer were concentrated in the areas which are highly expressed D3 receptor mRNA signals, e.g., hippocampus, cerebellum, hypothalamus, striatum and cortex. All these results suggest that(R, S)-[18F]-7-OH-AFPAT has the potential to be used as a new dopamine D3 receptor ligand in the study of distribution, function and pharmacological profiles of dopamine D3 receptor by PET or other medical investigations. In addition, a few new organic intermediates, e.g. 7-methoxy-2- [N- (3’-allyl)]aminotetralin, 7-methoxy-2-[N-(3’-allyl)-N-(3’-hydroxylpropyl)]-amiotetralin, 7-methoxy-2-[N-(3’-allyl)-N-(3’-toluenesulfonyloxypropyl)]-amiotetralin, 7-methoxy-2-[N-(3’-allyl)-N-(3’-fluorolpropyl)]amiotetralin and 7-hydroxyl-2-[N-(3’-allyl)-N-(3’-fluoropropyl)]-amiotetralin were firstly
IV. Accelerator Science and Technology 45
synthesized and identified during the synthesis of (R,S)-[18F]-7-OH-AFPAT. Besides, we have also completed: (1)the synthesis of the precursor of [ F]-Fallypride which is served as an excellent dopamine D2 receptor PET tracer in the study of brain functions and neurodisorders related to the dysfunction of DA receptor system; (2)the synthesis of the precursor of [18F]-FTHA which is served as PET tracer used in evaluation of myocardial long-chain fatty acid utilization.
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4.5.4
Other Basic and Application Research
The injector of the RFQ was tested. Now, the maximum beam current 50mA was obtained at the entrance of the RFQ. We will do some experiment to improve this value. The CCDTL structure was studied using aluminum model. The measured data are accorded with the calculated data. This will improve our designing ability on the CCDTL structure. In warrant time, the Dynamitron accelerator for Tianjin electrical wire factory was run normally. Now, the accelerator was handed over to them.