1. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 1 Summary of discussions involving (mainly): Jose-Luis Sanchez Alvarez Philippe Baudrenghien Gregoire Hagmann Matthias Haase Ioan Kozsar Christophe Martin Bettina Mikulec John Molendijk Mauro Paoluzzi Silvia Zorzetti More people to be consulted!

2. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 2 Why should one inhibit a PSB ring An operator asks for 0 turn to be injected (setting on OP display) A fault is detected (external-conditions inhibit chain) An experiment wants to stop the beam (external-conditions inhibit chain) What response time is expected 0 turn setting =>1 cycle (the next one typically) external-conditions => 2 cycles (after the “next” cycle) Fault (endangering acceleration or extraction) =>ASAP (not yet implemented)

3. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 3 The different ring-inhibits 0 turn settingonly changes counters’ value (until now) external-conditionsedits the PLS telegram where present and next are defined => thus implies more delay than the “0 turn” setting FaultNot yet implemented

4. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 4 Response to a fault Faults may occur at any time after the settings for the actual cycle have been established. Only the faults endangering the acceleration or the extraction are considered. Fault appears:What to do: Before injectionSkip the ring with the distributor or chop the beam During injectionSwitch to the next ring with the distributor or chop the remaining beam After injectionProgressive loss into the ring (with the rf) or extract to the dump (?)

5. A. Blas 5 For a proper injection from L4 into the PSB the following elements need to be synchronized: 1.Pre-chopper 2.Chopper 3.Cavities’ feed-forward (if needed) 4.Energy modulation cavities 5.Distributor 6.Injection kickers 7.Transverse Painting bumpers 8.Magnetic correction in each ring 9.LL-RF N.B.: all these elements (apart from the pre-chopper) can be programmed on a ring-by- ring base, meaning that advancing a start pulse allows for a ring skipping. PSB ring inhibit in the Linac 4 era PSB LIU meeting 07/03/2013

6. A. Blas 6 In case a ring would to be skipped - with the distributor - while the injection has started, the following elements could not follow: 1.Pre-chopper 2.Chopper 3.Cavities’ feed-forward (if needed) 4.Energy modulation cavities (20 us rise time) 5.Distributor 6.Injection kickers 7.Transverse Painting bumpers 8.Magnetic correction in each ring (some ms rise time) 9.LL-RF PSB ring inhibit in the Linac 4 era PSB LIU meeting 07/03/2013

7. A. Blas 7 Injection Timing – what is needed: Pre-chopperGlobal Start/Stop Timing ChopperUnique Start or Start for each ring + chopping table Cavities’ feed-forwardSynchronous with chopper Energy modulation cavities (longitudinal painting) Unique Start or Start for each ring + function (needs to start and end at zero for each ring) DistributorStart for each ring (+ tail dump) Injection kickersStart for each ring Transverse bumpers (painting)Start for each ring Magnetic correction in each ringUnique start or Start for each ring + function (or offset) – does not have to be precise LL-RFStart for each ring L4 to Booster synchro PSB LIU meeting 07/03/2013

8. A. Blas 8 L4 to Booster synchro Counter START C0 SINJ INJ REF 1 MHz Start Pre-chop Counter START Nb Turns R4 Counter START Nb Turns R3 Counter START Nb Turns R2 Counter START Nb Turns R2 Counter START Start Pre-chop SR4 SR2 SR3 SR1 RF synchro of all PSB rings PSB LIU meeting 07/03/2013

9. A. Blas 9 Timing summary: Information required in L4 for a smooth injection into the PSB: Reference clock + single start-injection pulse + number of turns In the PSB, a start injection pulse is required in each ring. Although the Linac 4 doesn’t strictly require a start corresponding to each ring,it can be set to work with. This would be an advantage for monitoring purposes (analysis on oasis for instance) There seem to be an agreement that a ring-by-ring time windowing would be beneficial for the entire L4 –PSB chain L4 to Booster synchro PSB LIU meeting 07/03/2013

10. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 10 Response to a Fault (part 2) Fault appears:What to do: Before injectionSkip the ring with the distributor or chop the beam During injectionSwitch to the next ring with the distributor or chop the remaining beam After injectionProgressive loss into the ring (with the rf) or extract to the dump (?) Switch to the next ring not compatible with longitudinal painting and magnetic correction -> Chopping is OK Switch to the next ring not compatible with magnetic correction -> Chopping is OK

11. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 11 Possible faults listed as “external conditions” that do not concern all rings (all rings = BIS issue) The rf faults could/should be added to this list. As mentioned before, these faults are presently treated after 2 cycles. External Conditions:Ring inhibited BE1.KFA1 BE2.KFA2 BE3.KFA3 BE4.KFA4 BT1.KFA101 BT4.KFA104 BT2.KFA201 + 2 BT1.SMV101 BT4.SMV104 BT2.SMV201 + 2 BT1.BVT101 BT4.BVT104 BT2.BVT201 + 2

12. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 12 With the increase of the injected beam energy and intensity, the response time to a “external condition” fault becomes difficult to accept. There is a need for a real time beam inhibit. One approach, that seems appealing (to some), is to chop the beam of the incriminated ring – with no delay The PSB timing remains the same, only the chopper disables the ring The rf of the given ring is disabled as a second security. When this emergency measure has been taken, the SIS (software Interlock System) disables the ring in a proper way by applying zero turn. No issue with magnetic correction, nor with the longitudinal painting (as compared to an emergency pulse that would switch to the next ring)

13. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 13 Summary Response to a fault jeopardizing the injection or acceleration: Ring inhibited with no delay Action: chopper and PSB RF + SIS applying 0 turn after processing time Response to an experiment ceasing to require beam (also called external condition?): Go to spare cycle or to zero cycle or ask for 0 turn All this in a controlled way with all machine parameters re-computed accordingly (no emergency actions required) Response to a zero turn command from the operation: Calculate all timings and functions for a proper operation (1 cycle duration?)

14. PSB ring inhibit in the Linac 4 era A. Blas PSB LIU meeting 07/03/2013 14 Hardware implications Real time inhibit at the chopper level (1 per ring) Real time inhibit on the PSB LL-RF (1 per ring) Centralize all detected-fault signals and determine the action depending on the cycle’s requirements in real time (RF interlock interface to be designed by Silvia Zorzetti)