remote setting of lhc blm thresholds?
DESCRIPTION
Remote setting of LHC BLM thresholds?. L. Ponce With contribution of C. Zamantzas, B. Dehning , E.B. Holzer, R. Schmidt, J. Wenninger,. Outlines. Overview of the system Need of changing the thresholds Proposed solution conclusions. 1. Recall: overview of the system. - PowerPoint PPT PresentationTRANSCRIPT
MPWG 9 March 2007 1
Remote setting of LHC BLM thresholds?
L. Ponce
With contribution of C. Zamantzas, B. Dehning, E.B.
Holzer, R. Schmidt, J. Wenninger,
MPWG 9 March 2007
Outlines
Overview of the system
Need of changing the thresholds
Proposed solution
conclusions
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1. Recall: overview of the system
Some 4000 monitors: mainly ionization chambers + SEM (for higher beam loss intensities)
All BLMs are interlocked and send a beam dump request if signal over threshold via the BIS
12 running sums (time windows) and 32 energy levels per monitor to cover the different loss durations
Speaking about changing thresholds, I would distinguish 2 main BLMs families:
BLM on cold element for quench protection (quad, main dip)
BLM on warm elements (for coll, injection, dump system…)
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BLMQI at the Quads (3 monitors per beam) + cold dipoles in LSS
Beam dump threshold set to 30 % of the quench level (to be discussed with the uncertainty on quench level knowledge)
Thresholds derived from loss maps (coll. team), secondaries shower simulations (BLM team), quench level simulations and measurements (D. Bocian)
BLMs for quench protection
beam 1
beam 2
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BLMs for warm elements
beam 1
beam 2
top view
BLM in LSS :at collimators, warm magnets, MSI, MSD, MKD,MKB, all the masks…
Beam dump threshold set to 10 % of equipment damage level (need equipments experts to set the correct values
TCTVBTDI
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2. Remotely changing the thresholds?
1. reasons to change the thresholds?
2. How often do we expect to have to change?
3. What can be implemented?
4. Consequences on the system reliability?
5. Who can do the change?
Questions addressed for preliminary discussions:
=> First set of comments are presented in the following
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Reasons to change the thresholds? How often?
1) to check Machine Protection functionalities of BLMs (interlocks): decrease the thresholds in order to provoke a dump with low intensity
frequency: during the commissioning, after each shut-down (?),
for a set of detectors
Will be a planned procedure
2) study/check of quench levels (“quench and learn” strategy?):
implies dedicated MD time, post-mortem data analysis, could be related
to check the correct setting of the thresholds
Frequency : ? Probably during shut-down
Note :for HERA, only one change since the start-up
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3) commissioning of individual systems (MSI, LBDS, collimators) : to get a loss picture of a region, to give “warning” levels
adjust thresholds after studies of the systems to optimize the operational efficiency vs. the irradiation level
frequency : 1 or 2 iterations after determination of the thresholds and localized in space (injection region, IR7…)
4) To match quench level during commissioning (operational
efficiency):
Probably few iterations
the needed flexibility is for decreasing thresholds would help operation but is it an absolute need ?
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3. Proposed implementation
Threshold GUI Reads the “master” table Applies a factor (<1) Saves new table to DB Sends new table to CPU
CPU flashes table if allowed (on-board switch)
Thresholds are loaded from the memory on the FPGA at boot.
Combiner initiated test allows CPU to read ‘current’ table.
SIS receives all tables
Compares tables Notifies BIS (if needed)
DETECTOR 16 – RS 12
DETECTOR 16 – RS 11
...
DETECTOR 01 – RS 03
DETECTOR 01 – RS 02
DETECTOR 01 – RS 01
DETECTOR 16 – RS 12
DETECTOR 16 – RS 11
...
DETECTOR 01 – RS 03
DETECTOR 01 – RS 02
DETECTOR 01 – RS 01
Master Table
Applied Table
Database
VME CPU
FLASH Threshold
Table
BLM Threshold Comparator
FLASH MEMORY
FPGA
SWITCH
VME Bus
READ Threshold
Table
BLM Combiner & Survey
SoftwareInterlock System
Threshold Preparation
GUI
CO
MP
AR
E T
HR
ES
HO
LD
S
FPGA
READ
APPLY FACTOR
SEND TOSYSTEMS
BIS
BIS
*
*
* *
*
*
* Secure transmission using MCS
FirmwareThresholds
MaskingOther
Note: possible upgrade by adding a comparison with master table on the board BUT feasibility and reliability have to be checked
Courtesy of C. Zamantzas
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Consequences on the reliability of the system?
We can chose to open/close the switch If we choose to have remote loading of the table, what does it mean for reliability? what about access to maskable/unmaskable table, enable/disable monitors
=> Problem of disabling monitors if no flexibility on thresholds adjustment
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4. Conclusions
Flexibility given by changing remotely the thresholds has to be balanced with the loss of reliability of the system
The proposed implementation allows both possibilities
But the remote access will have to be validated by machine protection experts when more detailed implementation of MCS and comparator are available (by the beginning of summer?).
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Systematic Uncertainties at Quench Levels
relative accuracies
Correction means
Electronics < 10 % Electronic calibration
Detector < 10 – 20 %
Source, sim., measurements
Radiation & analog elec.
about 1 %
fluence per proton < 10 - 30 %
sim., measurements with beam (sector test, DESY PhD)
Quench levels (sim.)
< 200 %measurements with beam (sector test), Lab meas., sim. fellow)
Topology of losses (sim.)
? Simulations
B. Dehning, LHC Radiation Day, 29/11/2005
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Thresholds and interlocks
12 running sums for 32 energy levels for each channel, 16 channels per card, 345 surface cards. → table of 2 millions values!
Any of this signal over the thresholds generate a beam dump request via the BIC
28
Tunnel Card BLMCFC
1 23 . . .
28
Ionisation Chamber
Patch Box
Surface Card BLMTC (DAB64x)
GOH
GOH
Surface FPGA
MEMORY 16 bits
16 bits
16 bits
Anti-Fuse FPGA
Control
Control
16 bits
Control
Mezzanine
SRAM (1)Acquisition Data
SRAM (2)Acquisition Data
SRAM (3)Post-Mortem
data
data
data
Power PC
Control
Data
VMEInterface
Control
Data
Control
Control
Control
Control
1 23 . . . 8
2|||||||||||||
|||||||||||||||
|||||||||||||||
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CFC Analogue
. . .
Control
TLKOptical receiver
16 bits
Control
TLKOptical receiver
16 bits
Control
TLKOptical receiver
16 bits
Control
TLKOptical receiver
16 bits
Control
GOL
GOL
Tunnel Card BLMCFC
GOH
GOH
16 bits
16 bits
Anti-Fuse FPGA
Control
Control
1 23 . . . 8
2|||||||||||||
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CFC Analogue
. . .
Control
GOL
GOLIonisation Chamber
Combiner CardBLMCOM
DUMP (x3)
BEAM ENERGY
BEAM PERMIT
Beam Interlock Controller
BIC DUMP (x2)
BEAM PERMIT
Beam Energy Tracker
BETBEAM ENERGY
optical fibres
VM
E6 4
x B
us
Bac
kpla
ne
DUMP (x3)
BEAM ENERGY
BEAM PERMIT
Control
Data
Tunnel max 2km Surface
max 300m
Ionisation Chamber
... ...
Ionisation Chamber
Post-Mortem
DataLogging
Data