- 300 turns achieved.

- Probably more but limited by libera cut-off frequency.

- Need to measure the injection axis

- Need emittance measurement from the transfer line

- Several measurements are not possible because of lack of progress on the transfer line

Shift summaries for the ring for last week are at

https://elog.lal.in2p3.fr/THOMX/Commissionning/568

https://elog.lal.in2p3.fr/THOMX/Commissionning/570

https://elog.lal.in2p3.fr/THOMX/Commissionning/571

The problem with the pulse jumpis with 12ns delays has been identified and fixed (it was related to the synchronisation system).

The main issue identified last week is a problem with RI-C2/PS/QP.09, RI-C2/PS/QP.10 and RI-C2/PS/QP.12 which has been addressed after the meeting (see https://elog.lal.in2p3.fr/THOMX/Commissionning/572).

It is important that the laser energy and linac beam charge are checked and optimised every week.

Slides are at https://indico.ijclab.in2p3.fr/event/8750/

- There is a difference in BPM numbering in Tango and MML => we should stick to Tango names.

- Beam was very unstable during the past week

- Difficulties to have full current on RI-C1/BPM.01. Signal drops already significanty before RI-C2/BPM.06

- Fluctuations may have been observed on the RF Gun power => to be confirmed

- Fluctuations have been observed on the kicker => may be due to energy jitter

To do:

- Monitor incident power on RF Gun

- Re-establish transport

- Try to inject with optimised TL transport

- Compare single pass and TbT BPM signals

- Check energy jitter in TL/BPM.02 and TL/SST.02

- Scan correctors to increase current on RI-C1/BPM.01 and RI-C2/BPM.06

- Start align beam in quadrupoles

Status slides presented by Iryna available on indico at https://indico.ijclab.in2p3.fr/event/8749/

The beam parameters required for a good injection in the ring were discussed.

The following required parameters were identified:

- At least 80pC on TL/DG/ICT.01

- At least 20pC on TL/DG/ICT.02

- Energy in the TL must be checked and must be 50 MeV.

- Beam position must be checked on TL/DG/SST.01, TL/DG/SST.02 and TL/DG/SST.03 and be within the acceptance (see tickbox acceptance on IHM_SST).

- Beam size must be measured on TL/DG/SST.03 and be < 2mm FWHM

- Beam recipes for the LI and for the TL must be saved.

- Health check must be checked (no red entry).

- Beam centered on the last quadrupole of the transfer line.

ACTION: Nicolas will create an interface that displays as many as possible of the required parameters.

Suggestion by Viktor: check phase noise at the gun entrance: there might a phase noise issue.

=> Vincent (VC) is going to do that with Viktor (VI) during RF studies on 26th September

Planning for the coming week:

- Wednesday: Slava (+Iryna after the CoDEC)

- Thursday: Nicolas + all

- Friday: AG Pole. Alexandre and Vincent plus Slava

Current objectives:

1) Re-establish beam transport to ring

2) Scan in time the septum

3) Scan in voltage the septum

4) Adjust timing of kicker by looking at induced noise on ICTs

5) Scan in time the kicker

6) Scan in voltage the kicker

7) Transport further in the ring by playing with correctors

Note: When possible Alexandre will test his feedback code.

The ring orbit has been re-established despite some difficulties after the shutdown.

The ring cavity has been started. Whatever the phase it kills the beam.
Two hypothesis:

1) It can be a frequency problem

2) It can be a transverse kick given by the cavity

About 1:

- Magnet current and frequency have been scanned but no effect.

About 2:

- We see betatron oscillation.

We see the beam lost by steps, not a continuous decrease.

https://elog.lal.in2p3.fr/THOMX/Commissionning/221202_190728/Screenshot_from_2022-12-02_18-02-36.png shows betatron oscillation with cavity tuned.

Next steps:

- Mesure FFT of BPM signal (VM, VC)

- "Open the ring" (kick the beam out of the ring) and study the effect of the cavity (phase, power) on the BPMs. (VK, IC)

- Scan betatron oscillation vs phase, orbit, power and frequency

- Slava: To catch the beam you should think like a beam.

Actions:

- Try to get remote control of RF synthetizer (ND)

Notes from last week:

• Beam was very unstable (probably energy instabilities), lot of time was spent tuning the injector.
• Beam instabilities prevented us from having a good storage.
• Unable to start the extraction line dipole.

Comments:

• It seems too early to plan radioprotection checks as:
  • we have not yet been able to store the beam and then extract it in a working extraction line.
  • beam is too unstable.
• Beam instabilities prevent progress on the ring studies.
• Beam stability characterisation of the upstream parts of the accelerator are necessary.

Summary of last week:

- On Thursday the beam energy was very different from usual (magnets current higher 172A for TL; 176A for RI) => made it impossible to re-use previous settings for the ring and to find new settings.

- On bith days, beam was unstable at TL/SST.02 and at the entrance of the ring. Part of the stability (but not enough) was recovered by setting TL/QP.4 and TL/QP5 to the same value.

=> not able to keep the beam in the ring for more than 500us or to inject more than 50pC.

Requirements to discuss on Friday:

- Get the results of the klystron power measurements

- Energy and charge stability

- Establish a working point for the lines.

- Linac alignement

Measurements to be done and documented:

- Stability of dark current (VM on 2/2)

- stability shot to shot and hourly-stability  (laser power, laser position, phase gun-laser [VC is working on it], phase gun-entrance section, phase gun-exit section, charge at the exit of the gun, charge at the exit of the section, energy and charge in the dispersive line)
=> charge stability measurement ND on 2/2 + 9/2.

- Dipole power supplies and dipole field

- RF power stability (Klystron, ...)

- Data alignement (ND on 2/2 + 2/9)

No beam last week. No beam this week.

Machine recovery on 2/2 => Nicolas may try to tune the machine with students.

Data taking on 9/2 for diags and machine characterization.

Next shift for the ring on Friday 17/2 + Friday 24/2 + Friday 10/3. No beam on 3/3 (winter vacation).

Beam on 9/3 will be dedivcated to BPM training for PERLE.

Reminder for the previous ring meeting - Measurements to be done and documented:

- Stability of dark current (VM on 2/2 or 9/2; ND to prepare the measure with ICT+WAC ; IC will prepare measure with scope)

- stability shot to shot and hourly-stability  (laser power, laser position, phase gun-laser [VC is working on it], phase gun-entrance section, phase gun-exit section, charge at the exit of the gun, charge at the exit of the section, energy and charge in the dispersive line)
=> charge stability measurement ND on 2/2 + 9/2.

- Data alignement (ND on 2/2 + 2/9)

Next ring meeting 13/2

This week: beam on Thursday.

So far we did not see any screenshot of Ring variables check.

Looking at last week's data, shot to shot charge instability seems to be > 15%

We need transverse emittance measurement for the ring shift (Thursday).

Excitation (betatron oscillation) on the beam observed by exciting it with the extraction kicker => initial measures of the tune.

Tune measured close from expected value.

Reason for oscillation damping is not understood.

The attenatuator of the RF section has to be tuned from time to time to keep the beam energy (beam position on TL/BPM.02).

Energy tolerance of the ring lattice: +/- 1% (but this may affect the transport upstram in the TL).

Next steps:

- Measure oscillations at different cavity power to see how they are affected.

- Went up to 100kV in the cavity once it was tuned.

- Achieved nice storage stable for 2500 turns and some beam for > 100ms

- Measured the tune: several peaks around 0.35[1] (near the expected value) and one peak not understood at 0.5

- We observed storage at different frequencies spaced by about 10kHz

- Shall we try to return close from the nominal frequency?

Current status wrt to X-ray search:

- First we need to be able to reach reproducable storage from day to day

- X-ray searches can be started parasitically when the beam is stored

- Better understanding of the beam will come through measurements (at least until the summer): precise measurements of optics, beam parameters will be possible only with repeatable operations. This is crucial to reach the target parameters of the ring.

Next steps:

- This week (Friday afternoon - if beam available): try to reproduce results from last Friday; store, study injection, dispersion

- Next week: Thursday continue work on reproducibility; Friday 31st: scan in frequency starting from nominal frequency at lower voltage.

=== Summary of last week:

- Frequency was reduced to 500.0202MHz but the beam stayed only for 100s of turns

- Good storage was achieved at 500.40MHz:

* Study of the effect of beam energy (linac section attenuator) on the orbit

* first attempts of BBA

=== Measures to do

Thursday: goal store at 500.0202MHz

- Use a spectrum analyser to check the FFT of the BPM electrodes as function of dipole current (Nicolas)

- Scan RF cavity (phase + plunger) at 500.0202MHz (Lisa+ Nicolas)

- check BPM convention (Lisa)

- Adjust beam energy (linac section attenuator and phase) to adjust ring frequency

Friday: Goal increase cavity voltage

- Orbit correction (BBA+SVD) (Iryna + Slava)

- Measure momentum compaction factor

Main studies:

- Measure bucket width in phase on Thursday at 500.02MHz => no storage beyond 45kV

- Measure frequency with spectrum analyser => 500.39MHz

- Preliminary study of BPM polarity

Next studies:

- Study again BPM polarities

- Redo spectrum analyser/FFT measurements of orbits at injection

- Study magnetic elements in balistic mode

- Visually look at the ring to see possible issues and changes to make

- Continue to do beam physics at 500.40MHz especially dynamic aperture

- Try to localize where losses occur during operations

Comments:

* There are strong evidences that part of the frequency problem comes from mechanical issue

* Fring field of the dipoles seems to be longer than anticipated. This could lead to shortening of the orbit.

Decisions:

* Have a meeting with mechanics to understand what are the issues and what are the possibilities to address the ring length issue.

* CFP is welcome to operate *remotely* during ring operations. A script will be made to monitor the X-ray flux during operations.

* Wednesday, Thursday and Friday : CFP can access until 11h.

* Investigate the operation of the BLM.

* Tuesday afternoon Nicolas and Sophie will investigate the feedback issue (phase or attenuator to stabilize TL/BPM.02/SpX).

Plan for this week: prepare the beam to test the X-ray production.

Report from last week:

- Attempted the strategy suggested by Alex

- Comparison of orbit with RF ON and RF OFF helped understand the "natural" frequency of the ring: 500.33MHz

- Attempts to store at 500.22MHz did not sicceed. Storage at 500.27MHz.

Goals for this week:

- Beam on Thursday and Friday

- Work on BBA (IC, VK, VM) + extraction and BPMs (ND, LS)

- Measure below deformation

Discussion mécanique

- Tous les dipoles ont été alignés par rapport à des surfaces de référence

- Le décalage du centre magnétique par rapport au centre mécanique a été mesuré par Cynthia et pris en compte lors de l'installation

- Difficile de décaler les dipoles de l'IP car la table a été ajoutée après et bloque le déplacement des dipoles.

- Pour déplacer tout le demi-anneau RI-C2 l'un des soufflets (près du septum risque d'être limitant). Très long temps d'approvisoinnement si l'on veut de nouveau soufflets.

- Le plus simple pour Rodolphe: bouger les 4 dipoles d'extremité (RI-C[1-2]DP.0[1,4]): 1 heure de travail (pour un test approximatif). Par contre pour revenir à une position intiale c'est 1/2 journée par dipôle.

- Pour réaligner les dipôles il faut que Denis calcul les nouveaux coordonnés.

Question à vérifier:

- est-ce que l'on a de la marge à l'IP pour déplacer les dipôles vers l'extérieur? [Mesure mardi matin avant 10h]

- quelle est la course possible pour le soufflet près du septum?

- Est-ce qu'il est possible de rattraper le fait que la chambre de RI-C2/DP.04 soit trop courte?

Stratégie:

(1) Mesure de la course possible vers l'extérieur des dipôle de l'IP

(2) Calcul par Denis des nouveux coordonnées de tous les dipôles décalés de 1mm vers l'extérieur radialement

(3) Si possible, décalage des 8 dipôles, sinon décalage de 4 dipôles.

Autre besoin:

- Faire étude sur dipôle de rechange en ajoutant des plaques en acier.

===

Objectifs de la semaine:

- Avancer sur l'orbite à 500.33MHz

- BBA

- Déplacement orbite dans IP (avec CFP)

- Vérifier/améliorer transport amont anneau

- Opérations avec ligne d'extraction

See attached files.

Transparents sur: https://indico.ijclab.in2p3.fr/event/9358/

Quelques notes de la réunion de Physique de ThomX:

- Présentation de Marie sur les mesures dans le linac

- Présentation de Slava sur les  progrès de l'anneau

Actions pour la prochaine réunion:

- Mesures de paramètres de Twiss TL/SST.01 et TL/SST.03 with LI/COL=220A and LI/COL= 225A

- Réduire la fréquence de l'anneau

This entry is to be updated as the work progresses.

1) Re-establish beam transport to ring

2) Scan in time the septum

see script git/panneaux/Synchro/scan_septum.py

3) Scan in voltage the septum

4) Adjust timing of kicker by looking at induced noise on ICTs

5) Scan in time the kicker

git/panneaux/Synchro/scan_kicker.py

6) Scan in voltage the kicker

7) Transport further in the ring by playing with correctors

Note: When possible Alexandre will test his feedback code.