Transcript LOCO test on SPS

Commissioning of
BLM system
L. Ponce
With the contribution of B. Dehning, E.B. Holzer,
M. Sapinski, C. Zamantzas and all BLM team
LHC Commissioning WG 27/03/2007
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Outlines
Overview of the BLM system
Principle of the simulations
Strategy for BLM positioning and the thresholds settings
Signal available
hardware commissioning
commissioning with beam
conclusions
LHC Commissioning WG 27/03/2007
BLM for machine protection
The only system to protect LHC from fast losses (between 0.4
and 10 ms)
The only system to prevent quench
Arc Dipole Magnet
dynamic range :
102 -1010
MIPs/(cm2s)
damage
Quench
BLM
BLM + QPS
BLM
LHC Commissioning WG 27/03/2007
BLM system : Detector
about 3600 ionisation chambers + 310
Secondary EMission detectors
measure the secondary shower outside
the cryostats created by the losses
dynamic range : 108 (or 1013 with SEM)
corresponding to few pA to 25 A
Ionisation chamber:
Diameter = 8.9 cm,
Length 60 cm, 1.5 litre,
Filled with N2
SEM
Diameter = 8.9 cm
Length 15 cm
LHC Commissioning WG 27/03/2007
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BLM system : signal chain
Tunnel
max 2km
Surface
max 300m
Post-Mortem
Data
Power PC
Control
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Anti-Fuse
FPGA
GOH
GOL
Control
Ionisation
Chamber
...
Ionisation
Chamber
optical fibres
16 bits
Control
GOH
Tunnel Card BLMCFC
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Patch Box
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Data
Control
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CFC Analogue
Ionisation
Chamber
Logging
GOL
Optical
receiver
TLK
16 bits
Control
Optical
receiver
TLK
16 bits
Control
Optical
receiver
TLK
16 bits
Control
Optical
receiver
TLK
16 bits
Control
Control
Data
data
Control
Surface
FPGA
data
Control
data
Control
Control
Data
VME
Interface
SRAM (1)
Acquisition Data
SRAM (2)
Acquisition Data
SRAM (3)
Post-Mortem
16 bits
GOL
DUMP (x3)
Control
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Anti-Fuse
FPGA
16 bits
GOH
MEMORY
Control
16 bits
BEAM PERMIT
Mezzanine
16 bits
GOL
Surface Card BLMTC (DAB64x)
Control
Control
BEAM ENERGY
Control
GOH
CFC Analogue
Backplane
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VME64x Bus
Data
2|||||||||||||
Ionisation
Chamber
16 bits
Tunnel Card BLMCFC
Beam Interlock
Controller
BEAM PERMIT
BIC
DUMP (x2)
Beam Energy
Tracker
Combiner Card
BLMCOM
BEAM PERMIT
BEAM ENERGY
DUMP (x3)
BEAM ENERGY
BET
8 channels per tunnel card, 2 tunnel cards per surface card and 335 surface
cards
12 integration periods and 32 energy level per channel (= per monitor)
signal over the thresholds generate a beam dump request via the BIC
Some channels can be maskable with the Safe_Beam flag
LHC Commissioning WG 27/03/2007
Simulation : loss locations
Loss pattern given by R. Assmann team (C. Bracco, S. Redaelli, G.
Robert-Demolaize) : Example (MQ27.R7)
Peak before MQ at the shrinking vacuum pipe location (aperture limit effect)
End of loss at the centre of the MQ (beam size effect)
LHC Commissioning WG 27/03/2007
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Simulation : geometry description
GEANT 3 simulation of the secondaries
shower created by a lost proton impacting the
beam pipe
simulation of the detector response to the
spectra registered in the left and right detector
(M. Stockner with G4)
500 protons same z position and same energy
Typical impacting angle is 0.25 mrad
longitudinal scan performed for primary impact
to optimize the BLM location
Top view
LHC Commissioning WG 27/03/2007
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Simulation : typical result
Longitudinal distribution of the
secondaries outside the cryostat in
DS for different loss location (z)
Maximum of the
shower ~ 1m after
impacting point in
material
increase of the signal
in magnet free
locations
factor 2 between
MQ and MB
z (cm)
LHC Commissioning WG 27/03/2007
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Simulation: Particle Shower in the Cryostat
example of MQ27R7: signal for each location given by the loss map (red) and “sum” signal (black)
Position of the detectors
optimized to:
catch the losses:
MB-MQ transition
Middle of MQ
MQ-MB transition
minimize
uncertainty of ratio
of deposited energy
in the coil and in the
detector
B1-B2
descrimination
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Strategy :BLM for quench prevention
beam 1
beam 2
At each Quads, 3 monitors per beam : 2 aperture limitation + middle
positions as much standardized as possible (integration problems) : same
procedure for quads in LSS

to define families of monitors (about 250)
Beam dump threshold set to 30 % of the quench level (to be discussed with the
uncertainty on quench level knowledge)
LHC Commissioning WG 27/03/2007
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Strategy: BLM for warm elements
beam 2
top view
collimator
TDI
beam 1
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)
Simulation from FLUKA team for IR7 and IR6, from MARS for IR3
LHC Commissioning WG 27/03/2007
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Generation of threshold table
Quench and damage level threshold tables will be created
for each family of BLM locations.
They will be assembled together into MASTER table
(damage or quench threshold vs beam energy and integration time)
For every location a threshold for 7 TeV beam will be
calculated (seed for parameterization).
Table will be filled from the seed using parameterized
dependence of quench level on Energy and Integration
time.
MASTER table, MAPPING table (BLM location vs
electronic channel) will be stored in LSA database.
LHC Commissioning WG 27/03/2007
Calibration and Verification of Models
Simulation is needed for :
secondaries shower simulation
magnet quench (dependance with beam energy, duration,
magnet types, 2 dim...)
detector response
Verification :
measurements of the tails of the secondary shower with
BLM on HERA dump : comparison with G4 simulation
(still to validate, M. Stockner)
quench tests campaign in SM18 for quench magnet model
verification (steady state losses) (D. Bocian, A. Siemko)
detector model checked with the CERN/H6 experiment
(M. Stockner PhD thesis)
LHC Commissioning WG 27/03/2007
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Proposed implementation
LSA Database
Threshold
Preparation
GUI
Threshold GUI
Software
Interlock
System
Master Table
DETECTOR 01 – RS 01
Reads the “master” table
Applies a factor to a family (<1)
Saves new table to DB
Sends new table to CPU
DETECTOR 01 – RS 02
*
*
DETECTOR 01 – RS 03
READ
...
DETECTOR 16 – RS 11
APPLY
FACTOR
COMPARE THRESHOLDS
DETECTOR 16 – RS 12
Applied Table
DETECTOR 01 – RS 01
DETECTOR 01 – RS 02
*
DETECTOR 01 – RS 03
*
...
DETECTOR 16 – RS 11
DETECTOR 16 – RS 12
SEND TO
SYSTEMS
VME CPU
*
FLASH
READ
Threshold
Table
Threshold
Table
* Secure
transmission
using MCS
BIS
Thresholds are loaded from the
memory on the FPGA at boot.
Combiner initiated test allows
CPU to read ‘current’ table.
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Concentrator receives all tables
VME Bus
SWITCH
Compares tables
Notifies BIS (if needed)
FLASH
MEMORY
Firmware
Thresholds
Masking
Other
CPU flashes table if allowed (onboard switch)
FPGA
BLM Threshold
Comparator
FPGA
BLM Combiner
& Survey
LHC Commissioning WG 27/03/2007
BIS
-> Details of implementation under
discussion
Consequences on the reliability of the system?
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Flexibility given by changing remotely the thresholds
has to be balanced with the loss of reliability of the
system
Possibility to scale the thresholds by families (to be discussed
which families and who can define it)
•
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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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BLM system : signals available
12 running sums (40 μs to 84 s) to cover the loss duration and 32
energy levels used for filling different buffers:
logging: at 1 Hz, max loss rate in each running sums over the last
second + corresponding quench levels + error and status from tests
Post-Mortem + study data : the last 1.7 s with a 40 μs sample rate
(43690 values) + the last 2 min of the logging data + thresholds and
masking tables + system status info
XPOC : possible to get up to 32000 values per channel for the
chosen running sum (need to be specified by LBDS)
Collimation: on request, 32 consecutive sums of 2,54 ms
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Fixed Display in the CCC
Used thresholds values
(change with energy)
Loss signals:
Max values of integration
intervals between 40 us
and 84s updated every 1 s
Values normalised to the
used thresholds or in Gy?
BLM concentrated by
quad?
If decided, possibility to
scale the thresholds table
by a factor F<1, by
families
LHC Commissioning WG 27/03/2007
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Other uses of BLM
Mobile BLM
Same Ionisation Chambers
use the spare channels per card : 2 in the arcs at each quad, a bit
more complicated in the LSS because of more elements.
electronics is commissioned as for connected channel
a separate Fixed display for non-active channels is planned : to be
discussed
No dump thresholds
BLM for ions:
same hardware, same electronics, same thresholds as for protons
(simulation from R. Bruce)
some more specific loss locations : on dipoles in DS and arcs of
IR7 and 3 (G. Bellodi, H. Braun), cells 11 & 13 in IR1 and IR5,
cells 10 & 12 in IR 2 (BFPP, J. Jowett and S. Gilardoni)
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Status of the system
Hardware: IC on time for LHC start-up, SEM delivery in
summer
Installation: sector 7-8 done (cables missing in 7 left),
sector 4-5 half done (delayed due to LHC schedule), 8-1 started
Acquisition system continuously running at HERA,
post-mortem + collimation data check at collimator MD
Threshold comparator software and combiner card (first version
done) to be implemented
Fixed display in CCC to be completed by CO
Threshold tables generation : start to specify and implement
post-mortem database and analysis still to be defined
Extensive software tools for data analysis (essential to fulfill the
specification). Start now to specify and implement
LHC Commissioning WG 27/03/2007
Hardware commissioning
complete detailed procedure documented in MTF
functionalities linked with Machine protection will be
reviewed in the Machine Protection System
Commissioning Sub-Working Group
validation of the connectivity topology: registration in
database of the link between position in the tunnelchannel identification-thresholds

Radiation source check (moving in the tunnel)
LHC Commissioning WG 27/03/2007
BLM Testing Procedures
Ph D thesis G.Guaglio
Detector
Tunnel
electronics
Surface
electronics
Combiner
Functional tests
Barcode check
Current source test (last installation step)
Radioactive source test (before start-up)
HV modulation test (implemented)
Beam inhibit lines tests
Threshold table beam inhibit test (under discussion)
10 pA test
Double optical line comparison (implemented)
Thresholds table and channel assignment SW checks
Inspection frequency:
Reception
Installation and yearly maintenance
LHC Commissioning WG 27/03/2007
Before (each) fill
Parallel with beam
Commissioning with beam
see presentation of A. Koschik in CHAMONIX 06
Motivation of the test:
Verification of the correlation between energy
deposition in the coil (= quench level) and BLM signal
(= thresholds)
Verify or establish „real-life“ quench levels
Verify simulated BLM signal and loss patterns
=> Accurately known quench levels will increase operational
efficiency!
simple idea: steer beam into aperture and cause magnet quench
possibility to check steady state losses quench limit with
circulating beam (part of the MPS commissioning)
possibility to check fast losses quench behavior if sector
test
LHC Commissioning WG 27/03/2007
Conditions for a quench test
Requirements :
Pilot beam 5x109
Clean conditions, orbit corrected (to better +/- 3 mm?): need to
know impact position and length for determination of the lost
proton density
BPM data/logging available -> Trajectory
BLM data/logging available
Up to 6 additional “mobile” BLMs at the chosen locations
Set optics
(3-bump)
Vary intensity
5x109 – max. 1x1011
+logging all relevant data (BPM,
BLM,BCT,emittance …)
LHC Commissioning WG 27/03/2007
Magnet quench
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Summary
BLM system designed to be reliable and cover the
specification of machine protection and quench prevention
Unique hardware and software for all spec to easy maintenance
Controlled, defined test with beam is essential for an early
verification of the BLM system, even if beam time consuming
Absolute quench limits and BLM threshold values
Model and understanding of correlation of loss pattern, quench level,
BLM signal
Remote access to the thresholds table has still to be approved
by machine protection experts
Specification of families to scale has to be defined (OP)
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