# Presentation: 801322

## Overall strategy for first years

## Commissioning with beam : The challenge

**There is a lot of stored energy in the nominal beams**
**7TeV, N****b**** = 2808, i****b**** = 1.15 10****11**** , (******** = 3.75 ********m, ************* = 0.55m)**
**Stored energy ~ 360MJ per beam**
**~ 0.7MJ melts 1kg copper**
**~ 100 ****•**** more stored energy than SPS / Tevatron / HERA**
**~ 1000 ****•**** more energy density than SPS / Tevatron / HERA**
**And they have to fit into a hole which is**
**	****	****	****very small ****	****	****	****	****very cold**

## Early physics running

**Both machine and experiments will have to learn how to stand running at nominal intensities, ****which will take some time**
**An early aim is to find a balance between robust operation and satisfying the experiments**
**Maximize integrated luminosity**
**Minimize event pile-up at the start ( to event + 2 )**
**Avoid quenches ( and damage )**
**Reduce energy to get more margin**
**Against transient beam losses**
**Against magnet operating close to training limit**
**Reduce total current to reduce stored beam energy**
**Lower i****b**
**Fewer bunches ( we have 25ns 75ns and others available )**
**Higher ************* to avoid problems in the (later part of the) squeeze**

## Energy & transient beam losses

**Quench if we surpass T****c**
**5 10****6**** could do it at 7TeV**
**Losses expected from**
**Injection, ramp**
**7TeV squeeze (aperture)**
**7TeV adjustments (collimators)**
**More margin at 6TeV**
**Less energy deposition at 6TeV**
**Together gain a factor 2 ?**

## Energy & magnet training

**Operation with beam should start at an energy for which the magnet system is very robust – regardless of the beam**
**We are at the mercy of the weakest magnets**
**Operation without beam should be performed with a current that is 200-300A above the level envisaged for luminosity operation**
**if hardware commissioning is done at 7TeV, start at < 6.8TeV**
**if we intend to operate for luminosity at 7TeV, we should first operate the hardware at 7.2TeV**
**This ensures that magnets will NOT quench if there is no beam**
**loss and no hardware failure**
**Magnet tests and hardware commissioning will tell us more**
**Post mortem recording to understand origin of quenches**

## Other considerations

**Electron cloud ( LHC simulations and SPS experience )**
**i****b**** < 35% nominal for 25ns spacing**
**i****b**** ~ nominal for > 50ns**
**With ****lower currents**** in mind, a number of machine systems will be staged**
**Only 8 of 20 beam dump dilution kickers initially installed**
**Total beam intensity < 50% nominal**
**Install the rest when needed**
**Collimators ( robustness, impedance and other issues )**
**Phased approach**
**Run at the impedance limit during phase I**
**Lower currents**
**Higher ***********
**Start simple, introduce the complexity (and the risk) in a controlled way**
**Emittance preservation in LHC will need learning**
**Assume ******** of 3.75 ********m at top energy also for reduced i****b**** **

## Resulting proposal for early physics running

**Start high energy operation at 6TeV or maybe 6.5TeV**
**Move to 7TeV whenever machine stability permits it ( 1 step )**
**Staged approach to get to stable 25ns operation**
**Commissioning and pilot physics run with few bunches**
**No parasitic bunch crossings**
**Machine de-bugging without crossing angle **
**75ns operation**** ****	**
**Establish multi-bunch operation**
**Relaxed machine parameters (squeeze and crossing angle) **
**25ns operation**
**Phase I collimators + partial beam dump**
**Phase II collimators + full beam dump**
**Also to accommodate**
**TOTEM runs**
**ION runs**

**6 month shutdown**

## Proposal for breakdown of a year

**Based on discussions with equipment groups (for Chamonix 2004)**
**Year ****	****	****= ****	****Shutdown + MCO + Operational period**
**Operational period ****	****= ****	****Beam periods + Technical stops**
**Beam period****	****	****= ****	****Setting up + MD + Physics**
**Year = 16 weeks Shutdown + 4 weeks MCO + 32 weeks Operation**
**Operational period = ****1****{ 25 days Beam period + 3 days Technical Stop }****8**
**Beam period = 1 day Setting up + 4 days MD(16%) + 20 days Physics(80%)**
**First beam period will always be for setting up + a little physics**
**Results in around 140 days for physics**
**To be shared between proton running, ion running and TOTEM**

## First 4 or 5 years will be something like this

## Or maybe this

## First commissioning with beam

## Overall schedule is under review

**New planning will try to minimise the impact of the delay**
**QRL**
**Installation of machine components, sectors in parallel **
**Hardware commissioning of power circuits, sectors in parallel **
**Allow overlap of activities (QRL tests, magnet installation, interconnects)**
**End of hardware commissioning = ****T****0**** for operations**
**At this point**
**All 8 sectors have been cooled down and powered to nominal**
**All special function equipment has been commissioned**
**Access and power interlock systems commissioned by sector**
**Beam vacuum prepared at sector level**
**Machine checkout**** (getting ready for beam)**
**Do as much as possible before T****0**** (resources)**
**Be as fast as possible after T****0 ****(working 24/7)**
**Beam commissioning with staged approach in mind**
**Go for first collisions with single or large-spaced bunches**

## Machine checkout before T0 (normal hours)

**Machine checkout ****before T****0**** (normal hours)**

**Close each sector and test the integrity of the access system**
**Doors, SAS**
**Break chains and check response**
**Check safety elements**
**Over 4 weekends during Sector 12 commissioning**
**Functionality tests of the access system for whole machine**
**Re-establish beam vacuum conditions in all sectors**
**Exercise all sector valves in/out**
**Sector valves and access system**
**Pressure and beam dump interlocks**
**In 81 45 34 78 56 67 (assume 12 23 OK)**
**Re-establish QPS conditions by sector**
**Re-establish power interlock conditions (PIC) by sector**
**Re-start power circuits and other equipment by sector**
**Re-calibrate power converters by sector**
**Start all this at T****0**** – 3 months ( in // with 12 23 HC )**
**Driven by operations**
**Will need support of equipment specialists when things don’t work**

## Machine checkout after T0 (24/7)

**Machine checkout ****after T****0**** (24/7)**

**Access system**
**Close machine (patrols)****	****	****	****	****	****2 days**
**Full systematic check of the whole machine****	****	****	****4 days**
**SAS / Doors / EIS equipment**
**DSO tests****	****	****	****	****	****	****	****2 days**
**Vacuum system****	****	****	****	****	****	****5 days**
**Check when any valve closes the interlocks react correctly**
**Measure pressure profiles around the ring**
**Switch everything ON, cycle and set to 450GeV****	****	****10 days**
**Interleave day / night with vacuum work ?****	**
**Establish beam interlock conditions (BIC) ****	****	****	****4 days**
**INB tests****	****	****	****	****	****	****	****2 days**
** ****	****Ready for first beam ( with plenty of MC still to do )****	****	****29 days**

## Interleaved MC and Beam Commissioning

**Interleaved ****MC**** and ****Beam Commissioning**

**Drive all systems through the operational cycle (dry runs)**
**Has to be done before ramping with beam**
**Estimated duration****	****	****	****	****	****	****( 1 month )**
**Beam Commissioning of single/few bunch operation (no trains)**
**First turn, ring 2**
**Circulating beam, ring 2**
**450GeV – preliminary system commissioning**
**450GeV – detailed measurement program**
**450GeV – 2 beams**
**Switch to nominal cycle**
**Snapback, single beam**
**Ramp, single beam**
**Single beam at physics energy**
**2 beams to physics energy**
**Physics with unsqueezed beams**
**Commission squeeze**
**Physics with partially squeezed beams, no crossing angle**
**Some phases can/will be done in different order**
**Estimated duration****	****	****	****	****	****	****3 months**
**Followed by a pilot run / machine studies in coast****	****	****1 month**

## Important points on Beam commissioning

**Beam commissioning is for single/few bunches per beam**
**No or very little work with 25ns or 75ns beams**
**Start with simplest possible machine**
**Special magnetic cycle**
**Special tunes**
**Minimum number of electrical circuits**
**Only have the machine interlocks that we absolutely need**
**Assumes no major show-stoppers due to **
**Transfer functions of key magnetic elements**
**Alignment errors (particularly the triplet)**
**Magnet polarities**
**Aperture restrictions**
**Matching dipole field of each arc to the beam**
**Reference magnet system**
**Machine protection systems need to be done together**
**Beam loss system**
**Beam dump system**
**Collimation system**
**Machine interlock systems**
**Other ideas**
**Dry runs on rest of machine during recovery from quenches**
**Commission ramp to lower energy (1 TeV) with shorter cycle**

## Manpower Strategy

## We will need for normal operation (year 3+)

**Machine supervisor****	****	****weekly responsibility****	****	****need 4**
**EIC****	****	****	****	****on shift****	****	****	****need 7**
**Operator****	****	****	****on shift****	****	****	****need 7**
**Cryogenics operator****	****on shift****	****	****	****need 7**
**Accelerator Systems ****support**
**Accelerator Physics support**

## Commissioning scenario

**LHC Commissioning Coordinator**
**weekly responsibility for year 1, maybe year 2**
**Shift workers**
**CIC (on shift for year 1, maybe year 2)**
**EIC for the future (on shift long term)**
**Operator (on shift long term)**
**Hardware commissioning veteran (year 1)**
**Accelerator Systems Responsibilities**
**Accelerator Physics Responsibilities**

## LHC Commissioning Coordinator (LCC)

**Role: **
**to take overall responsibility for implementing the LHC commissioning program over a limited time period. This will involve supervising and directing the shift crews, ensuring the necessary follow up is done, chairing daily commissioning meetings and reporting progress and problems to the wider community. Expect that this will entail spending 16h per day in and around the control room.**
**Qualification: **
**Experienced accelerator physicist. Must have a thorough knowledge of the LHC and the commissioning plan. Must have a wide knowledge of the supporting equipment groups. Experience of doing a similar job would be a clear advantage.**** **

## Commissioner in Charge (CIC)

**Role: **
**to push forward the LHC commissioning program during his shift, under the direction of a Commissioning Coordinator. This will entail driving the machine and making the necessary beam related measurements. **
**Qualification: **
**Experienced accelerator physicist. Must have a good knowledge of the LHC machine and physics. Must be committed to doing this until the LHC operation becomes routine enough to leave to the EIC (see below).**

## Engineer in Charge

**Role: **
**to assist the CIC, and learn how to run the machine, so that from year 2, maybe 3, he/she will take over full responsibility for LHC operation during a shift.**
**Qualification: **
**Physicist or Engineer. Expect to draw on staff with experience as EIC on other machines, or who have worked on LHC construction projects. We should aim to hire a pool of scientists with a wide range of specialties, each of which brings their own ideas on how to improve operations. Must be prepared to perform this role for 4 or 5 years, before moving on to other things (maybe Machine Supervisor).**** **

## Operator

**Role: **
**to assist the EIC and CIC on shift.**
**Qualification:**
**Experienced accelerator operator. Good knowledge of the LHC machine. Expect to draw on staff with experience of LHC hardware commissioning or LHC magnetic measurements.**** **

## Hardware commissioning veteran

**Role: **
**to provide on-hand expertise of the LHC equipment on shift.**
**Qualification:**
**Experience of LHC hardware commissioning. May not be needed if a sufficient number of operators are drawn from the hardware commissioning team.**

## Accelerator Systems Responsibilities 

**All accelerator systems will need to be commissioned, first during hardware commissioning and later with beam. Once a system has been made to run, it will need frequent expert support to make it continue to work. **
**While responsibility for the performance of any accelerator system rests clearly with the group(s) concerned, it would prove extremely useful to have personnel directly concerned with machine operation also involved. This would result in a number of mini-teams responsible for the exploitation of particular accelerator systems. **

## Accelerator systems

**Responsible known**

| System | Responsible | OP / LARP |  ABP / LARP |
| --- | --- | --- | --- |
| Controls |  |  |  |
| Applications software |  |  |  |
| Hardware commissioning |  |  |  |
| Accelerator Technical Services |  |  |  |
| Vacuum |  |  |  |
| Cryogenics |  |  |  |
| Access |  |  |  |
| Radio protection |  |  |  |
| Transfer line magnetic elements |  |  |  |
| Injection elements
Kickers
Septa |  |  |  |
| Beam instrumentation
Screens
BCT
BPM, trajectory and orbit correction
BLM
PLL for Q, Q’, coupling
Profile monitors
Luminosity monitors |  |  |  |

## Accelerator systems continued

**Responsible known**

| System | Responsible | OP / LARP |  ABP / LARP |
| --- | --- | --- | --- |
| Magnet circuits and power converters |  |  |  |
| Reference Magnet System |  |  |  |
| RF
Power
Low level |  |  |  |
| Longitudinal feedback |  |  |  |
| Transverse feedback |  |  |  |
| Experiment solenoids and compensations |  |  |  |
| Experiment equipment (Roman pots, velo) |  |  |  |
| Quench Protection System (QPS) |  |  |  |
| Powering Interlock System (PIC) |  |  |  |
| Beam Interlock System (BIC) |  |  |  |
| Energy Extraction System |  |  |  |
| Beam Dumping System |  |  |  |
| Collimation System |  |  |  |
| Protection Devices |  |  |  |

## Accelerator Physics Responsibilities

**We will need a pool of accelerator physicists ready to push through particular phases of the commissioning program and to pick up on the inevitable surprises that will crop up along the way. Qualifications are very similar to those of the CIC. Although not shift work, must be committed to doing this until the LHC operation becomes routine. **
**We will also need accelerator physicists responsible for specific aspects, or ‘beam-based systems’. This could be done in the style of mini-teams responsible for particular systems.**

## Beam commissioning phases

|   | Phase |   |
| --- | --- | --- |
| 1 | First turn | Ring 2; Ring1. Commission injection, thread beam around first turn, commission relevant beam instrumentation. |
| 2 | Circulating beam | Ring2; Ring 1. Capture, adjustment of key beam parameters |
| 3 | 450 GeV - Preliminary system commissioning |   |
| 4 | 450 GeV - Detailed measurement program | Increase current, machine protection, transverse damper, aperture, optics. |
| 5 | 450 GeV - two beams | Pilots → higher intensity. Separation bumps, BLMs, crosstalk |
| 6 | Switch to nominal cycle |   |
| 7 | Snapback – single beam,  | Ring 2, ring 1 |
| 8 | Ramp  - single beams | Single beam, ring 2; ring1. Stop in ramp. Commission beam dump, machine protection in ramp, ring 2. |
| 9 | Single beam at physics energy | Ring 2, ring1 (± separation bump). Measurements. |
| 10 | Two beams to physics energy Collide pilots.  Unsqueezed. | Collide procedure - first pass. |
| 11 | Physics. Unsqueezed. | Experiments on. Increase to 43 on 43 |
| 12 | Commission squeeze | Single beam partially through squeeze, etc. |
| 13 | Physics with partially squeezed beams. No crossing angle. |   |

## Beam based accelerator systems

| System | AP | OP |  LARP / other |
| --- | --- | --- | --- |
| Beam in the injectors |  |  |  |
| SPS extraction, transfer, injection and first turn |  |  |  |
| Multi turn losses and BIS dependability |  |  |  |
| Clean Beam Extraction |  |  |  |
| Filling efficiency and flat bottom conditions |  |  |  |
| Ramp and squeeze quality |  |  |  |
| Longitudinal plane |  |  |  |
| Optics |  |  |  |
| Aperture |  |  |  |
| Field quality |  |  |  |
| Lifetimes |  |  |  |
| Separation schemes |  |  |  |
| Crossing angle schemes |  |  |  |
| Collisions and luminosity |  |  |  |
| Experimental conditions |  |  |  |
| Ions |  |  |  |

## LARP involvement

**In the present US-LARP proposal, resources are allocated for “Beam Commissioning and Accelerator Physics” activities from 2004 onwards, rising to significant numbers by 2007. In the discussions to date, we have made the point that the US-LARP commitment has to be made with long-term individual commitments of around 12 months, and that US staff should come to perform a specific role in the beam commissioning work. It has also been clearly said that CERN has to maintain sufficient expertise, particularly on shift, to ensure long-term exploitation of the machine.**
**With this in mind, we feel that a very limited number of US-LARP resources could participate in the shift rota. Rather, they would be best suited to the accelerator physics and equipment group support activities listed above.**