BEPCII Event Timing System Ge LEI for BEPCII

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

Brief Introduction to BEPC-II BEPC--Constructed in 1984 – 1988; Operation 1988 -2005 Single Ring collider, Beam energy: 1 – 2. 8 Ge. V Physics Run：Lum. 1031 cm-2 s-1 @ 1. 89 Ge. V, 5 month/year Syn. Rad. Run： 140 m. A @ 2. 2 Ge. V, 3 month/year EPICS 2008, Shanghai BEPCII Timing System 2

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

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

BEPCII Schedule of Commissioning -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) 1032 cm-2 s-1 EPICS 2008, Shanghai BEPCII Timing System 5

BEPC-II timing system, an event timing system EPICS 2008, Shanghai BEPCII Timing System 6

BEPC-II timing related Parameters colliding mode ring circumference energy RF frequency harmonic number revolution frequency linac repetition rate linac RF frequence EPICS 2008, Shanghai SR mode 237. 531 m 241. 129 m 1. 89 Ge. V 2. 5 Ge. V 499. 8 MHz 396 402 1. 262 MHz 1. 243 MHz 5, 12. 5, 25, 50 Hz 2856 MHz BEPCII Timing System 7

BEPC-II timing system requirements delay resolution RMS jitter in respect to RF Clock Injection kickers 2 ns e-Gun 10 ps < 100 ps < 35 ps other triggers clock <200 ps <100 ps EPICS 2008, Shanghai 10 ns BEPCII Timing System 8

BEPCII timing system layout • Black boxes are timing stations • Blue lines: timing multi-mode fiber cables • Red lines: 499. 8 MHz reference distribution. • Greed line: 10 MHz synchronizing cable from linac master osc. to ring RF osc. EPICS 2008, Shanghai BEPCII Timing System 9

BEPCII timing structure EPICS 2008, Shanghai BEPCII Timing System 10

BEPCII timing system hardware • • • 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-4 Vs for Kickers 18 sets of home-made E/O and O/E for linac EPICS 2008, Shanghai BEPCII Timing System 11

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 EPICS 2008, Shanghai BEPCII Timing System 12

To select any bucket • The event clock is set to 499. 8 MHz/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 Sequence. RAM unit number, Bn is the bucket number. – Using the above formula, any unit from 0 to 395 in Seq. RAM 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, Seq. RAM unit to bucket number. Transform it to a table mapping bucket number to Seq. RAM unit number. EPICS 2008, Shanghai BEPCII Timing System 13

Map bucket number to Sequence. RAM unit number (partly) B Seq. R k A k A k A t M t M t M 0 0 4 68 8 136 12 204 1 215 5 283 9 351 13 23 2 34 6 102 10 170 14 238 3 249 7 317 11 385 15 57 EPICS 2008, Shanghai 1 6 1 7 1 8 1 9 272 91 306 125 BEPCII Timing System 14

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 Seq. RAM 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) EPICS 2008, Shanghai BEPCII Timing System 15

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 50 Hz – 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 Seq. RAM unit, – Set event code to the above unit in Seq. RAM of EVG EPICS 2008, Shanghai BEPCII Timing System 16

bkt. Record. dbd • • • • BKSE, DBF_LONG, BER Total. Bucket. Numbers BKSP, DBF_LONG, BPR Total. Bucket. Numbers BKSS, DBF_LONG, BSR Total. Bucket. Numbers BKTE, DBF_LONG, BER Bucket. Inj BKTP, DBF_LONG, BPR Bucket. Inj BKTS, DBF_LONG, BER Bucket. Inj 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 Seq. RAM delay to EVG INJ, DBF_UCHAR, if is injecting LBKT, DBF_LONG, Last Bucket injected EPICS 2008, Shanghai BEPCII Timing System 17

bkt. Record. dbd • • • MAX, DBF_LONG, max bcm protection value MODE, DBF_MENU, BEPCIIoperation. Mode RLPE, DBF_UCHAR, Re. Load. Pattern. File of BER RLPP, DBF_UCHAR, Re. Load. Pattern. File of BPR RLPS, DBF_UCHAR, Re. Load. Pattern. File of BSR RMMD, DBF_MENU, Reflective. Memory. Mode RMEO, DBF_LONG, Reflective. Memory BER Offset for bucket 0 RMPO, DBF_LONG, Reflective. Memory BPR Offset for bucket 0 RMSO, DBF_LONG, Reflective. Memory BPR Offset for bucket 0 SEQO, DBF_LONG, EVG Seq. RAM offset for bucket 0 TPUP, DBF_LONG, topup auto. Inj. Min. Bkt EPICS 2008, Shanghai BEPCII Timing System 18

bkt. Record. 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 ASL 1, special SPC_DBADDR, • BCMP, DBF_NOACCESS, – – BCM readout for BER extra char bcmp[402] asl ASL 1, special SPC_DBADDR EPICS 2008, Shanghai BEPCII Timing System 19

Multi bunch injection control EPICS 2008, Shanghai BEPCII Timing System 20

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 EPICS 2008, Shanghai BEPCII Timing System 21

BCM display of 20 * 20 buckets colliding EPICS 2008, Shanghai BEPCII Timing System 22

Revolution frequency Since our event clock is selected as 499. 8 MHz/5 = 99. 96 MHz, no way to generate revolution frequency directly by EVG/EVR with this clock rate. 1. Second EVG of event clock 499. 8 MHz/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. 8 MHz Output: 499. 8 MHz/396 or 499. 8 MHz/402 Made by an institute in Beijing Has been working well since Feb. 2008. EPICS 2008, Shanghai BEPCII Timing System 23

EPICS 2008, Shanghai BEPCII Timing System 24

Performance: jitter of transport line beam signal (taken from TC-BCT 2) to 499. 8 MHz RF signal is less then 16 pico seconds. On Apr. 26, 2007, last for 20 minutes. EPICS 2008, Shanghai BEPCII Timing System 25

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 50 Hz 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. EPICS 2008, Shanghai BEPCII Timing System 26

Thank you! EPICS 2008, Shanghai BEPCII Timing System 27