Dedicated MD 2025-12-01

Kevin has given EPA 3h to measure SFT-like injection (14 GeV) with different preceeding cycles. We will have time 15:00-18:00 with proton beam.

On afternoon shift: James & Manuel Night shift before: Maggie & Serge

Cycles

• MD cycle (MD2): SFT_PRO_MD_aperture_2025_V3, with 1 injection from PS MTE_CORE_2025, and MTE_Core_2025 from PSB, roughly 1e12 intensity.
• High energy cycle (LHCPILOT): LHC_PILOT_Q20_2025_V1, no beam
• MD1-like cycle (MD4): MD_26_L60_Q20_2022_V1_Clone_MD_to_flat, no beam

BCDs

• LHCPILOT (PROTON) - 26 GeV MD4 - MD
• LHCPILOT (PROTON) - MD (exponential-like trim needed)

• LHCPILOT (ION) w/ 400 GeV dynamic economy (SFT-like) - MD4 - MD

• LHCPILOT (ION) w/ 400 GeV dynamic economy (SFT-like) - 26 GeV MD4 - MD
• LHCPILOT (ION) w/ 400 GeV dynamic economy (SFT-like) - MD

• LHCPILOT - MD4 - MD (reference measurement, already exist, in case of time)

The sequences can be duplicated (i.e. x2) if PS needs longer supercycle.

• -6 to 6 permil dp/p in 0.5 permil, repeat 3-5 times per point

AOB

LSA parameters to work with

In LSA app suite in the CCM.

Global settings

Dynamic economy end time

Accessed through SPSRING → BP (0 -> [C_END]) → MOMENTUM / TUNE → FGC_63/REF.ECONOMY.DYN_END_TIME

Dynamic Economy is controlled by

• MBI/REF.ECONOMY.DYN_END_TIME#value
• QD/REF.ECONOMY.DYN_END_TIME#value
• QF/REF.ECONOMY.DYN_END_TIME#value

Which sets the end time (i.e. where the dynamically generated function connects to the LSA setting), which controls which field level the real field reaches.

Set to 0 to disable, or set to cycle end time to never meet the reference function, but N.B. that the cycle ramps down from injection energy, so a small hysteresis loop is excited.

Ask operators to enable/disable economy modes, or use the SPS Economy app with their permission.

Beam-process related settings

Main bending field

Accessed through SPSRING → [Beam process] → MOMENTUM → B

Main dipole field is controlled by

• SPSBEAM/B (DO NOT TRIM THIS)
• SPSBEAM/BHYS (copies B)

Work only with CORRECTION field, and prefer working directly in the injection beam process.

Info

You need to enable Expert settings to trim main bends. Always double check what you send. ;)

Tune

Accessed through SPSRING → [Beam process] → TUNE → Q

Main tune is controlled by

• SPSBEAM/QH
• SPSBEAM/QV

Trim on correction or value.

Chromaticity

Accessed through SPSRING → [Beam process] → CHROMATICITY → QPRIME

Chromatic sextupoles are controlled by

• SPSBEAM/QPH
• SPSBEAM/QPV

Trim on correction or value.

Transverse dampers

Accessed through SPSRING → [Beam process] → RF_TRANSVERSE_DAMPER → ALLTFBHLP//Damper, then in the rightmost column instead of Device/Property, select Device/Property#field

Transverse dampers controlled mainly by

• SA.TFBHLP.H/Damper#LoopGain (horizontal plane)
• SA.TFBHLP.V/Damper#LoopGain (vertical plane)
• SA.TFBHLP.H/Damper#CentralPhase
• SA.TFBHLP.V/Damper#CentralPhase

By default it’s set to 0 on our MD cycle.

LSA Tags

Several LSA tags are set up to make it easy to switch between settings. They are accessed through LSA App suite → Applications toolbar → Settings → Tag Management, where a tag can be selected and loaded.

The tags contain Momentum / Tune / Chromaticity knob and IMAINS/IREF settings.

MD set up

Recommended applications

• OpenYASP (Steering), 2x windows
  • Orbit evolution over time (top bar Machine Specials → Multiple Acquisitions)
  • First turn radial position (acquire FT on main window)
• LSA App suite, 2-3 windows
  • Better to have one window for each setting to change (B & tune) instead of switching back and forth.
• Auto Q - Frequency / tune spectrum over time with excitation, also for chroma measurement with auto $\frac{dp}{p}$ trims to LSA.
• Q Meter - Quick tunes at discrete locations in the cycle
• Screenshot app - Log to SPS_MDs.

Checklist

• Ask operators to set up the two BCDs before start of MD, and fill cycles in PS and PSB. Ensure all cycles are mapped (MD2, MD4).
• Open all required apps

MD Execution

Measurement checklist

For each chroma measurement

• Center the beam orbit by trimming main bends Main bending field
• Recover tune working point by trimming tune Tune
  • If beam goes unstable, try slightly decreasing chroma ($\pm$ 0.1) Chromaticity
• Note down mean orbit and first turn offset, take screenshots
• Screenshot B setting
• Screenshot tune (BBQ)
• Set up chroma acquisition
  • Screenshot acquisition settings
• Note down start and end times of chroma scan

Measure the BCDs in the provided order.

Eddy current decay

When placing the MD cycle right after a fast ramp-down, and “exponential-like” trim will be needed on main B and Q.

Reasonable values

Expect changes in $\Delta B=\pm 1.4\times 10^{-4}T$ and $\Delta Q_{x,y}=\pm 0.08$. When MD1 is suppressed main dipole normally needs to increase by $1.2\times 10^{-4}T$, and $Q_{x,y}$ by $0.08$

Aperture cycle tags

2 set of tags have been made from previous measurements which can be used as baselines for further adjustments

• with 200 GeV MD1
• without MD1 (3x ZERO)

Flat / 26 GeV / standard MD1

Use the MD4, which should have the 26 GeV ramp up and down already configured.

3 tags exist for easily switching between flat (idle current), 26 GeV, and standard MD1.

• Full MD1 (200 GeV)
• Flat (idle current) dipole and quadrupole
• 26 GeV MD1

Expect to change both $B$ and $Q$ when changing MD1

LHCION2 DYNECO end times

The following DYNECO end times are computed for LHCION2 (add +/- 0.1 s increments to adjust if necessary) to reach desired max field. A python notebook is also available.

	momentum	target_field	dyneco_end_time_ms
0	450	2.02
1	400	1.8	7062.68
2	300	1.35	7362.58
3	270	1.215	7449.13
4	200	0.9	7640.1
5	100	nan
6	34	0.154	8090.21
7	26	0.116	8182.83
8	14	0.063