1. EPICS 2008, ShanghaiBEPCII Timing System1 BEPC-II Event Timing System Ge LEI for BEPC-II timing team Institute of High Energy Physics, Beijing Mar. 2008

2. EPICS 2008, ShanghaiBEPCII Timing System2 Brief Introduction to BEPC-II BEPC--Constructed in 1984 –1988; Operation 1988-2005 Single Ring collider, Beam energy: 1 – 2.8 GeV Physics Run ： Lum. 10 31 cm -2 s -1 @ 1.89GeV, 5 month/year Syn. Rad. Run ： 140mA @ 2.2 GeV, 3 month/year

3. EPICS 2008, ShanghaiBEPCII Timing System3 Design Goals of BEPCII The BEPCII continues to serve the purposes of both high energy physics experiments and synchrotron radiation applications.

4. EPICS 2008, ShanghaiBEPCII Timing System4 SR mode: outer ring (BSR) Col. mode: e+ ring (BPR) e- ring (BER) Commissioning Phase 1 ： Backup Scheme Phase 2 ： With SCQ Phase 3 ： With detector e+ e SR

5. EPICS 2008, ShanghaiBEPCII Timing System5 -Jan. 31 Beam collision tuning with SCQ to improve the luminosity & minimize the background Feb. 26 -- One month of SR operation Mar. 26 Shutdown for detector to move in May 14 Start collision tuning with detector on line Test run of HEP experiment Dec. 2008 Lum. (1.0~3.0)  10 32 cm -2 s -1 BEPCII Schedule of Commissioning

6. EPICS 2008, ShanghaiBEPCII Timing System6 BEPC-II timing system, an event timing system

7. EPICS 2008, ShanghaiBEPCII Timing System7 BEPC-II timing related Parameters colliding modeSR mode ring circumference237.531m241.129m energy1.89GeV2.5GeV RF frequency499.8MHz harmonic number396402 revolution frequency1.262MHz1.243MHz linac repetition rate5, 12.5, 25, 50Hz linac RF frequence2856MHz

8. EPICS 2008, ShanghaiBEPCII Timing System8 BEPC-II timing system requirements delay resolutionRMS jitter in respect to RF Clock Injection kickers2ns< 100 ps e-Gun10ps< 35ps other triggers10ns<200ps clock<100ps

9. EPICS 2008, ShanghaiBEPCII Timing System9 Black boxes are timing stations Blue lines: timing multi-mode fiber cables Red lines: 499.8MHz reference distribution. Greed line: 10MHz synchronizing cable from linac master osc. to ring RF osc. BEPCII timing system layout

10. EPICS 2008, ShanghaiBEPCII Timing System10 BEPCII timing structure

11. EPICS 2008, ShanghaiBEPCII Timing System11 2 EVGs, 18 EVRs 13 VME crates and controllers, 2 levels of fanout, 5 Fout-7 modules in total. GUN-TX and Gun-Rx for e-gun pulser timing 4 TD-4Vs for Kickers 18 sets of home-made E/O and O/E for linac BEPCII timing system hardware

12. EPICS 2008, ShanghaiBEPCII Timing System12 What are special in BEPCII event timing Hardware developed –18 sets of optical transmitting/receiving boards, for gun power supply, positron source, and 16 modulators (LI Gang, LE Qi) –Gun-Rx module modified to generate NIM outputs directly (WANG Lin) –Revolution frequency Software –Make every bucket selectable –Fast bucket selection: a dedicated record support and device support developed for fast bucket selection

13. EPICS 2008, ShanghaiBEPCII Timing System13 To select any bucket The event clock is set to 499.8MHz/5. –Reason: In EVG-200, the event clock is generated from RF divided by 4,5,6,8,10 and 12, among which only 5 is a prime numver. event-clock/7 is set to be the sequencer clock –Reason: 7 is a common factor of BEPCII ring RF and linac RF frequnecy. Bn = MOD(Rn*35, 396), for BEPCII colliding mode –Rn is the SequenceRAM unit number, Bn is the bucket number. –Using the above formula, any unit from 0 to 395 in SeqRAM can be mapped to one and only one bucket in the ring, which has 396 buckets in total. The above formula can generate a table, SeqRAM unit to bucket number. Transform it to a table mapping bucket number to SeqRAM unit number.

14. EPICS 2008, ShanghaiBEPCII Timing System14 Map bucket number to SequenceRAM unit number (partly) BktSeqRAMBktSeqRAMBktSeqRAMBktSeqRAMBktSeqRAM 0046881361220416272 12155283935113231791 2346102101701423818306 3249731711385155719125

15. EPICS 2008, ShanghaiBEPCII Timing System15 To select any bucket This table is put into an array of one-dimension in our dedicated record support which does the fast bucket selection. The n-th element of table gives the SeqRAM unit which generates the n-th bucket to the ring. Similarly, we generate the mapping table for BEPCII synchronized radiation mode by Bn = MOD(Rn*35, 402)

16. EPICS 2008, ShanghaiBEPCII Timing System16 Fast bucket selection event timing + Beam Current Monitor A new EPICS record support has been created to do the fast bucket selection, –Damping time consideration, bucket switch in 50Hz –protection to BCM hardware process –read BCM values from reflective memory card of BI group, select a bucket of smallest bunch current –map the bucket number into corresponding SeqRAM unit, –Set event code to the above unit in SeqRAM of EVG

17. EPICS 2008, ShanghaiBEPCII Timing System17 bktRecord.dbd BKSE, DBF_LONG, BER TotalBucketNumbers BKSP, DBF_LONG, BPR TotalBucketNumbers BKSS, DBF_LONG, BSR TotalBucketNumbers BKTE, DBF_LONG, BER BucketInj BKTP, DBF_LONG, BPR BucketInj BKTS, DBF_LONG, BER BucketInj BSEL, DBF_LONG, bucket selection method COUN, DBF_LONG, count CNTD, DBF_LONG, count down DONE, DBF_LONG, all buckets done ENKE, DBF_OUTLINK, Enable/Disable Kicker e- ENKP, DBF_OUTLINK, Enable/Disable Kicker e+ EVG, DBF_OUTLINK, Output SeqRAM delay to EVG INJ, DBF_UCHAR, if is injecting LBKT, DBF_LONG, Last Bucket injected

18. EPICS 2008, ShanghaiBEPCII Timing System18 bktRecord.dbd MAX, DBF_LONG, max bcm protection value MODE, DBF_MENU, BEPCIIoperationMode RLPE, DBF_UCHAR, ReLoadPatternFile of BER RLPP, DBF_UCHAR, ReLoadPatternFile of BPR RLPS, DBF_UCHAR, ReLoadPatternFile of BSR RMMD, DBF_MENU, ReflectiveMemoryMode RMEO, DBF_LONG, ReflectiveMemory BER Offset for bucket 0 RMPO, DBF_LONG, ReflectiveMemory BPR Offset for bucket 0 RMSO, DBF_LONG, ReflectiveMemory BPR Offset for bucket 0 SEQO, DBF_LONG, EVG SeqRAM offset for bucket 0 TPUP, DBF_LONG, topup autoInjMinBkt

19. EPICS 2008, ShanghaiBEPCII Timing System19 bktRecord.dbd PTRE, DBF_NOACCESS, BER Pattern ， extra int ptre[402] PTRP, DBF_NOACCESS, BPR Pattern ， extra int ptrp[402] PTRS, DBF_NOACCESS, BSR Pattern ， extra int ptrs[402] BCME, DBF_NOACCESS, –BCM readout for BER –extra char bcme[402] –asl ASL1, –special SPC_DBADDR, BCMP, DBF_NOACCESS, –BCM readout for BER –extra char bcmp[402] –asl ASL1, –special SPC_DBADDR

20. EPICS 2008, ShanghaiBEPCII Timing System20 Multi bunch injection control

21. EPICS 2008, ShanghaiBEPCII Timing System21 Multi-bunch injection control Control when to inject and when to stop –Top-off injection, a control loop –Stop injection when all buckets reach the bunch current limit Bucket select method –The smallest the first –Next smaller than the bunch limit, according to the sequence in the injection pattern definition file Criterion –Beam current from DCCT, or bunch current from BCM Injection pattern definition file: ASCII files

22. EPICS 2008, ShanghaiBEPCII Timing System22 BCM display of 20 * 20 buckets colliding

23. EPICS 2008, ShanghaiBEPCII Timing System23 Revolution frequency Since our event clock is selected as 499.8MHz/5 = 99.96MHz, no way to generate revolution frequency directly by EVG/EVR with this clock rate. 1.Second EVG of event clock 499.8MHz/4, this method has been using from Oct 2007 to Feb. 2008, second round commissioning for colliding mode of BEPCII 2.Develop a revolution frequency module Input: Ring RF 499.8MHz Output: 499.8MHz/396 or 499.8MHz/402 Made by an institute in Beijing Has been working well since Feb. 2008.

24. EPICS 2008, ShanghaiBEPCII Timing System24

25. EPICS 2008, ShanghaiBEPCII Timing System25 Performance: jitter of transport line beam signal (taken from TC-BCT2) to 499.8MHz RF signal is less then 16 pico seconds. On Apr. 26, 2007, last for 20 minutes.

26. EPICS 2008, ShanghaiBEPCII Timing System26 Acknowledgement Work done by Ge Lei, Guanglei Xu, Lin Wang, Gang Li, Wenchun Gao, etc. Thanks to the cooperation. Many thanks to the discussions and suggestions of Jukka Pietarinen (MRF Oy.), Kazuro Furukawa (KEKB), Timo Korhonen (SLS), Dekang Liu and Liying Zhao (SSRF), Angelos Gorias and Yuri Chernousko (DLS). Special thanks to the 50Hz module from Yuri Chernousko. Many thanks to the suggestions and cooperation of the colleagues in group of AP, BI, PS Injection, RF, Linac Power Source, Linac Microwave, and detector of BEPCII project.

27. EPICS 2008, ShanghaiBEPCII Timing System27 Thank you!