Programmed dumps (incl. inject

1
Programmed dumps (incl. inject dump)

• LBDS functional architecture
• Use-case overviews
• Inject and dump between 0 1000 turns
• Inject and dump between 0.1 and 1000 seconds
• Programmed dumps during injection process
• Programmed dump at end-of-fill
• Programmed dump of one beam
• Requirements on other systems
• Implementation
• Annex (use-case details)

2
LBDs functional architecture

• LBDS interfaces for arming, triggering and energy
  tracking
• DCCTs in 4 of the LHC arcs, and in IR6, for the
  BETS
• RF system, for the abort gap fast timing
• injection interlock system, to allow the dump to
  be armed
• BIS beam interlock system via the local BIC
  client interface
• redundant IR6 beam loss system, to trigger LBDS
  independently of BIS
• access system, to dump beam without passing
  through BIS

3
Inject and dump I 0 1000 turns

• For injection setting-up with screens, and
  studies requiring less than 100 ms of circulating
  beam, e.g. aperture measurements in
  injection/extraction channel.
• Will use a dedicated hardware system to trigger
  the beam dump via the BIS
• Necessary to dump after less than one full turn,
  to ensure that injection setting up with screens
  can be performed with a single beam impact.
• To protect the screens, maximum number of turns
  has to be limited.
• Preferable that this mode limited to Safe Beam
  from SPS if not, then procedure is more
  complicated, requiring pilot injection prior to
  high-intensity injection, to ensure circulating
  beam condition is met.
• The other entry conditions are that the LHC
  machine is at injection energy, that the beam
  permit for the selected ring is TRUE.
• Use a timing event at 100 ms (or even few ms
  after the requested number of turns) to provide
  redundancy for increased screen protection

4
Inject and dump II 0.1 1000 seconds

• This mode is required for longer delays between
  injecting and dumping
• Will use the timing system to trigger the beam
  dump via the BIS.
• Screens are NOT allowed to be in the beam
• Again, for simplicity, it would be preferred that
  this mode can only be used with the Safe Beam
  from the SPS, but this is less important since
  interlocking should anyway ensure that the
  screens cannot be used

5
Dump of intermediate beam during injection

• A programmed dump during the nominal injection
  sequence is required to dispose of the
  intermediate beam injected after the pilot bunch
  (cannot be dumped parasitically onto the TDI
  injection collimator).
• Will use the timing system to trigger the beam
  dump via the BIS.
• Variations on the theme will be needed, according
  to whether both rings are filled alternately or
  sequentially, and on the details of the
  adjustment and filling phases.
• The question of whether the BIS/LBDS should
  enforce a dump of both rings in the event of a
  beam permit FALSE for one ring still needs to be
  decided it would increase the operational
  flexibility, but reduce the safety, since some
  interlock channels with separate signals for beam
  1 and beam 2 may be cross-connected. Work in
  progress with interlock team e.g. on making this
  conditional on machine mode.

6
Dump of both beams at end-of-fill

• A programmed dump at the end-of-fill will be
  required, for example when the specific
  luminosity is low enough that the machine
  requires refilling.
• Will use the timing system to trigger the beam
  dump via the BIS.
• The dump request will be managed by the
  sequencer, which must make sure that the entry
  conditions are satisfied, and that any
  preparatory steps concerning e.g. the
  experiments, the movable devices etc. are first
  executed

7
Dump of one beam

• A programmed dump of one beam is a possible
  requirement, for example for machine studies at
  the end of a fill.
• Will use the timing system to trigger the beam
  dump via the BIS.
• The dump request will be managed by the
  sequencer, which must make sure that the entry
  conditions are satisfied, and that any
  preparatory steps concerning e.g. the
  experiments, the movable devices etc. are first
  executed.
• Condition under which this is possible need
  definition

8
Protection of BTV screens at injection

• Inject and Dump I mode needed to ensure
  protection of screens only used when LHC is in
  this mode AND turns requested less than safe
  limit (depends on screen type (Al2O3 or Ti) and
  intensity)
• Assuming only safe beam can be used
• Al2O3 screens withstand 1013 p/mm2, and Ti
  screens 1014 p/mm2. For nominal optics, p
  density at screen for injected nominal batch of
  3.3?1013 p is 1.1?1013 P/mm2.
• Assuming that the safe beam limit is 1012 p at
  450 GeV, safe number of turns for Ti screens is
  300, and for Al2O3 screens 30.
• Taking ?3 margin, max. turns with safe beam
  should be 100 for Ti and 10 for Al2O3 screens.
• To be implemented in SW interlock which uses
  number of turns requested and screen position to
  allow or inhibit injection.
• HW interlock from screens to inhibit user permit
  for unsafe beam, if screen in beam.
• Assuming any beam can be used
• Product of turns ? intensity must not exceed
  1013 for Al2O3, and 1014 for Ti screen (i.e. 3
  turns with full intensity, or 2?104 turns with
  pilot bunch).
• To be implemented in SW interlock which uses
  measured beam intensity (in SPS), number of turns
  requested and screen position to allow or inhibit
  injection.
• Additional protection measures
• Limit the maximum number of turns to 1000 in
  Inject Dump I HW
• In this mode always include a timing event at 100
  ms (or more closely linked to turns requested).
• As a real HW interlock with no software
  dependence, use BLMs at each screen, with
  interlock threshold at an appropriate integration
  time, to dump beam if losses detected exceed
  dangerous level.

9
Interlock and dump systems

• BIS used to trigger beam dump for all programmed
  dumps. BIS must therefore provide a reliable and
  deterministic response to interrupt in IR6 coming
  from Inject and Dump I system, such that beam can
  reliably be dumped after programmed number of
  turns.
• BIS must also provide an automatic reset for
  certain machine modes, in order that repeated
  injection or injection sequence can continue.
  (Alternatively such functionality could be
  provided by sequencer which works in a quasi
  real-time loop?)
• The following functionalities are required
• Triggering via timing system (delay can be of the
  order of a few turns)
• Automatic reset conditional on machine mode (from
  SMP)
• SW input channel for XPOC inhibit
• LBDS must be re-armed after every action, which
  is foreseen to be requested by the sequencer.
• LBDS IPOC and XPOC results must be positive and
  beam permit loop is then forced close during a
  short period, while LBDS inhibits injection and
  forces its own user permit true.

10
Timing, RF and SMP systems

• The timing system will be used for the Inject and
  Dump II mode and for the other programmed dump
  events. The following timing system
  functionalities are required
• Distributing Programmed dump
• Distributing XPOC request events (tbc)
• Distributing PM request events conditional on
  machine mode and dump type
• The following RF system functionalities are
  required
• Injection prepulse to IR6 (RA63/67) assume 10
  ?s before injection (tbc). Needs new fibres.
• Revolution frequency to IR6 (RA63/67) already
  exists to LBDS TSU
• For the Safe Machine Parameters the LHC mode must
  be distributed to the BIS, for conditioning the
  automatic reset (alternatively mode must be
  available to the sequencer which will manage
  reset).
• The mode is also needed for the screens, to
  prevent any movement while beam can be injected
  or present.

11
Beam screens and SW interlocks

• The beam screens must be protected against
  damage, and this requires interlocking on their
  position, conditional on the machine mode and
  intensity.
• The following functionalities are required
• HW interlock if moving
• HW interlock if unsafe beam (tbc depending if
  Inject Dump I limited to safe beam)
• Read of screen position and type (for SW
  interlock)
• Dedicated interlock BLMs with thresholds adapted
  to protect the screens
• Movement inhibited in any machine mode where beam
  can be present
• The following SW interlocks are required
• Inhibit injection if screens moving
• Inhibit injection if screens in beam and unsafe
  beam (tbc)
• Inhibit injection if screens in beam and machine
  mode ltgt Inject and Dump I
• Inhibit injection if screens in beam and ID I
  system turns gt100
• Inhibit injection if screens in beam and turns ?
  intensity gt 1013 (Al2O3) or 1014 (Ti)

12
Sequencer and XPOC

• The sequencer must provide the high-level
  management of the inject and dump machine modes
  and of the other programmed dumps. The following
  functionalities are required
• managing machine mode changes
• configuring all the systems to meet the entry
  conditions
• checking that the entry conditions are met
• generating the timing events with the correct
  delays
• setting the turn counter value
• requesting checks before injection is enabled
• requesting the correct beam from the SPS
• reading the XPOC result
• arming and re-arming the LBDS
• re-arming the BIS (tbc)
• The XPOC needs to acquire and check data
  associated with beam dump action. The process
  must inhibit beam permit via a software channel
  while busy. The XPOC needs to return an answer
  within about 10 s, in order to allow for repeated
  injections in Inject and Dump mode.

13
Implementation

• BT (i.e. Etienne) will build the new HW
• Schematic architecture of LBDS with new inject
  and dump crate shown below

14
New Inject Dump HW

• Assumed HW located in a rack or racks in point 6
  underground, in RA63/67, to minimise the reaction
  times with the beam permit loop.
• Present prepulse envisaged 10 ?s prior to
  injection, to minimise dead time of MKI when
  injection kick can no longer be stopped.
• Detailed analysis of response times and signal
  delays to be made, to determine whether this is
  adequate for deterministic dumping on turn 0, or
  whether another separate prepulse needs to be
  generated with a longer delay to trigger this
  system.
• The following functionalities are required
• Triggering by RF prepulse
• Turn counting via RF frequency
• Interrupt of beam permit loop
• Adjustable delay in order to trim the system
  synchronisation during setting up
• Set requested turns via LSA (MCS?)
• Read of requested turns via LSA (for SW
  interlocks)

15
Issues

• Need a better name than Inject and Dump I
  system.
• Limit inject and dump I mode (with 0 1000
  turns) to safe beam intensity?
• Easier to implement safer for screens
• Operational constraints?
• Are the limits 0 1000 turns and 0.1 1000
  seconds reasonable?
• Is 10 ms injection prepulse delay enough for 0
  turns?
• Delay accounting and tests to be made
• Otherwise need separate pre-pulse with few 100
  ms?
• Is the proposed protection for the screens
  adequate?
• Not clear that local private turn counters safer
  BLMs to be defined and feasibility checked
• To be discussed in upcoming MPWG
• Conditions to dump one beam? Arm inject with
  other beam permit false?
• Automatic reset of BIS are we sure that this
  does not impact the reliability?
• Sequencer work still to be done to define
  detailed requirements
• Can this be used to reset the BIS?
• XPOC and PM triggering, data acquisition and
  pathways work still needed
• LHC machine mode details
• Can Inject and dump I and Inject and dump II
  be combined? Interlocking implications?
• Present definitions require extension links to
  sequencing and interlocking

16
Use-case details
17
Inject and dump I 0 1000 turns

• i. Machine mode is changed to Inject and Dump I
  by the LHC sequencer
• ii. Number of turns selected between 0 and 1000
  and loaded into Inject and Dump hardware by
  sequencer
• iii. Request dump Timing event delay set at 100
  ms or corresponding value
• iv. Checks made of screen positions and requested
  turns resident in the Inject and Dump hardware by
  the LHC sequencer - injection is inhibited if
• a. screens are MOVING
• b. OR the screens are IN and the mode is not
  Inject and Dump I
• c. OR the number of turns requested exceeds the
  safe limit.
• v. Safe beam is requested from the SPS by the LHC
  sequencer
• vi. Beam is injected and the turn-counter
  triggered in the Inject and Dump hardware
• vii. After the programmed number of turns, the
  Inject and Dump Hardware triggers beam dump via
  BIS
• viii. The timing system generates a request
  XPOC timing event, after receiving a dump
  request associated with a request dump timing
  event while in Inject and Dump I mode OR
  specific shot-by-shot transient data logging data
  is acquired, associated with the injection and
  with the beam dump. No request PM event is
  issued
• ix. The XPOC process inhibits the injection by
  the SW user permit channel of the BIS
• x. The data required for the XPOC is transferred
  to the servers and analysed by the XPOC process
• xi. If the dump action was correctly executed the
  XPOC process gives the user permit
• xii. The BIS makes an automatic reset, possible
  for Inject and Dump I Machine Mode
• xiii. The sequencer launches the arm LBDS
  sub-sequence

18
Inject and dump II 0.1 1000 seconds

• i. Machine mode is changed to Inject and Dump
  II by the LHC sequencer
• ii. Delay time selected between 0.1 and 1000
  seconds and loaded into the timing system by the
  LHC sequencer
• iii. Checks are made of injection screen
  positions and screen types by the LHC sequencer -
  injection is inhibited if any screens are IN or
  MOVING
• iv. Safe beam is requested from the SPS by the
  LHC sequencer
• v. Beam is injected
• vi. After the appropriate delay, the timing
  system issues an event which is received by the
  BIS and triggers the beam dump by opening the
  beam permit loop
• No request PM event is issued. The timing
  system generates a request XPOC timing event,
  after receiving a dump request associated with a
  request dump timing event while in Inject and
  Dump II mode OR specific shot-by-shot
  transient data logging data is acquired,
  associated with the injection and with the beam
  dump.
• The XPOC process inhibits the injection by the SW
  user permit channel of the BIS
• ix. The data required for the XPOC is transferred
  to the servers and analysed by the XPOC process
• x. If the dump action was correctly executed the
  XPOC process gives the user permit
• xi. The BIS makes an automatic reset, possible
  for Inject and Dump II Machine Mode
• xii. The sequencer launches the arm LBDS
  sub-sequence

19
Inject and dump II 0.1 1000 seconds

• i. Normal Injection Sequence started by the LHC
  sequencer
• ii. Pilot beam is injected and adjusted, then the
  intermediate beam is over-injected (in this case
  the pilot is deflected onto the TDI) and
  adjusted
• iii. Once both rings of the machine are judged
  satisfactory with the intermediate beam, the
  Injection Sequence is launched
• iv. Via the sequencer, generate and issue a
  timing event which is received by the BIS and
  triggers the beam dump for both rings by opening
  the beam permit loop
• v. No request PM event is issued. The timing
  system generates a request XPOC timing event,
  after receiving a dump request associated with a
  request dump timing event while in Inject and
  Dump II mode OR specific shot-by-shot
  transient data logging data is acquired,
  associated with the injection and with the beam
  dump.
• vi. The XPOC process inhibits the injection by
  the SW user permit channel of the BIS
• vii. The data required for the XPOC is
  transferred to the servers and analysed by the
  XPOC process
• viii. If the dump action was correctly executed
  the XPOC process gives the user permit
• ix. The BIS makes an automatic reset, possible
  for Normal Injection Machine Mode
• x. The sequencer launches the arm LBDS
  sub-sequence
• xi. Inject a pilot bunch into Ring 1 and Ring 2
• xii. Change to nominal beam in the SPS
• xiii. Start injecting the nominal beam,
  over-injecting the pilots in Ring 1 and Ring 2

20
Dump of both beams at end-of-fill

• i. Machine mode is set to Unstable
  Beams/Adjust by the LHC sequencer
• ii. Preparatory steps executed by the LHC
  sequencer for machine, experiments, beam
• iii. Generate and issue timing event(s) which is
  received by the BIS and triggers the beam dump
  for both rings by opening the beam permit loops
• iv. The timing system generates a request PM
  timing event, after receiving a dump request
  associated with a request dump timing event.
  Possibly the specific shot-by-shot transient data
  logging data is still acquired, associated with
  the beam dump, depending on details of the XPOC
  data acquisition
• v. The XPOC process inhibits the SW user permit
  channel of the BIS
• vi. The data required for the XPOC is transferred
  to the servers and analysed by the XPOC process
• vii. If the dump action was correctly executed
  the XPOC process gives the user permit
• viii. The BIS does NOT make an automatic reset

21
Dump of one beam

• i. Machine mode is set to Unstable
  Beams/Adjust/??? by the LHC sequencer
• ii. Preparatory steps executed by the LHC
  sequencer (?)
• iii. Generate and issue timing event(s) which is
  received by the BIS and triggers the beam dump
  for one rings by opening the beam permit loop
• The timing system DOES NOT generates a request
  PM timing event. Possibly the specific
  shot-by-shot transient data logging data is still
  acquired, associated with the beam dump,
  depending on details of the XPOC data
  acquisition.
• The XPOC process inhibits the SW user permit
  channel of the BIS for the appropriate beam
• vi. The data required for the XPOC is transferred
  to the servers and analysed by the XPOC process
• vii. If the dump action was correctly executed
  the XPOC process gives the user permit
• viii. The BIS does NOT make an automatic reset