Post on 15-Dec-2015
transcript
EPICS 2008, Shanghai BEPCII Timing System 1
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 2
Brief Introduction to BEPC-IIBrief Introduction to BEPC-II
BEPC--Constructed in 1984 –1988; Operation 1988-2005
Single Ring collider, Beam energy: 1 – 2.8 GeV
Physics Run : Lum. 1031cm-2s-1 @ 1.89GeV, 5 month/year
Syn. Rad. Run : 140mA @ 2.2 GeV, 3 month/year
EPICS 2008, Shanghai BEPCII Timing System 3
Design Goals of BEPCIIDesign 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 4
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
EPICS 2008, Shanghai BEPCII Timing System 5
-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) 1032cm-2s-1
BEPCII Schedule of CommissioningBEPCII Schedule of Commissioning
EPICS 2008, Shanghai BEPCII Timing System 6
BEPC-II timing system,an event timing system
EPICS 2008, Shanghai BEPCII Timing System 7
BEPC-II timing related Parameters
colliding mode SR mode
ring circumference 237.531m 241.129m
energy 1.89GeV 2.5GeV
RF frequency 499.8MHz
harmonic number 396 402
revolution frequency 1.262MHz 1.243MHz
linac repetition rate 5, 12.5, 25, 50Hz
linac RF frequence 2856MHz
EPICS 2008, Shanghai BEPCII Timing System 8
BEPC-II timing system requirements
delay resolution RMS jitter in respect to RF Clock
Injection kickers 2ns < 100 ps
e-Gun 10ps < 35ps
other triggers 10ns <200ps
clock <100ps
EPICS 2008, Shanghai BEPCII Timing System 9
• 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
master
BCM,Libera TB-BI
ModulatorsBI
eGun
2856MHz
Feedback
BES
e- SR
e+ SR
e+Kicker
e-Kicker
RF
RF
EPICS 2008, Shanghai BEPCII Timing System 10
BEPCII timing
structure
EV
G
Fan
out
499.
8MH
z 50
Hz
TT
L
Fan
out
Fan
out
Fan
out
EV
R
330m fiber cable
EVR330m fiber cable
EVREVR
EVR
120m fiber cable EVR
EVR
EVR
EVR
EVR
16 Modulaters
BT BPM
feedback
e- camera
BCM
e+ camera
120m fiber cable
EVR
EVR
EVR
EVR
EVR BT BCT
Fast bucket select
e- Kickers
BES
e+Kickers
…...
E-Gun
AmplifierPSK
Gun PSe+ PS
Linac BI
GU
N-T
X
EVRLibera BPM
120m fiber cable
EPICS 2008, Shanghai BEPCII Timing System 11
• 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
EPICS 2008, Shanghai BEPCII Timing System 12
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 13
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.
EPICS 2008, Shanghai BEPCII Timing System 14
Map bucket number to SequenceRAM unit number(partly)
Bkt SeqRAM Bkt SeqRAM Bkt SeqRAM Bkt SeqRAM Bkt SeqRAM
0 0 4 68 8 136 12 204 16 272
1 215 5 283 9 351 13 23 17 91
2 34 6 102 10 170 14 238 18 306
3 249 7 317 11 385 15 57 19 125
EPICS 2008, Shanghai BEPCII Timing System 15
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)
EPICS 2008, Shanghai BEPCII Timing System 16
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
EPICS 2008, Shanghai BEPCII Timing System 17
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
EPICS 2008, Shanghai BEPCII Timing System 18
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
EPICS 2008, Shanghai BEPCII Timing System 19
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
EPICS 2008, Shanghai BEPCII Timing System 20
Multi bunch injection control
EPICS 2008, Shanghai BEPCII Timing System 21
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 22
BCM display of 20 * 20 buckets colliding
EPICS 2008, Shanghai BEPCII Timing System 23
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.
EPICS 2008, Shanghai BEPCII Timing System 24
EV
GE
vent
Clo
ck
=49
9.8M
Hz/
5
Fan
out
499.
8MH
z
50H
z T
TL
Fan
out
Fan
out
Fan
out
EV
R
330m fiber cable
EVR330m fiber cable
EVREVR
EVR
120m fiber cable EVR
EVR
EVR
EVR
EVR
16 Modulaters
BT BPM
feedback
e- camera
BCM
e+ camera
120m fiber cable
EVR
EVR
EVR
EVR
EVR BT BCT
Fast bucket select
e- Kickers
BES
e+Kickers
…...
E-Gun
AmplifierPSK
Gun PSe+ PSLinac BI
GU
N-T
X
EVRLibera BPM
120m fiber cable
Agi
lent
E
4434
B
Spl
itte
r
Mai
ns
Syn
ch.
EV
GE
vent
Clo
ck
=49
9.8M
Hz/
4
Fan
out
499.
8MH
z
50H
z T
TL
EVR Libera BPM
EPICS 2008, Shanghai BEPCII Timing System 25
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.
EPICS 2008, Shanghai BEPCII Timing System 26
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.
EPICS 2008, Shanghai BEPCII Timing System 27
Thank you!