1. HALF SECTOR TEST: a test for the future PSB injection
G. Guidoboni
BE-OP-PSB
OP Shutdown Lectures
March 7, 2017

2. OUTLINE Motivation PSB Half Sector Test elements Installation
Operations
First beam
Controls and applications
SF experience and instrumentation debugging
Solved issues
Beam transmission issue
Steering on H0/H- monitor and beam shape
Measurement programs
Summary and conclusions
Acronyms:
HST= Half Sector Tests
SF = Stripping Foil

3. No easy way back to Linac2 injection
MOTIVATION
New PSB injection: main changes
New injector, Linac4 (Linac2 replacement, equipment aging)
Injection energy from 50 MeV to 160 MeV.
New H- charge exchange injection:
Injection bump with 4 BSW magnets
Stripping foil between BSW2 and 3 converting H- into p (~98% efficiency expected)
Transverse painting of PSB acceptance with painting bump (KSW)
Bunch-to-bucket transfer and longitudinal painting
Linac2 replacement, equipment aging
Mitigate the direct space charge effect
Increase maximum beam brightness and intensity available from PSB
Allows to inject more time in the same phase space
New distributor, remove septum and other hardware changes
Losses on septum for conventional multi-turn injection disappear
Attention to increased activation by 160 MeV ions
No easy way back to Linac2 injection

4. MOTIVATION New PSB injection: injection section
BSW4 +
H0/H- Dump
extremely compact and complex installation
charge exchange injection (no experience at CERN)
BHZ
BSW3
Test it before final installation!
STR
BSW2
BSW1
~2.65m
Beam direction
BHZ

5. MOTIVATION Half Sector test Circulating
p beam
Commissioning of the new PSB injection:
BSW4 +
H0/H- Dump
Stripping foil (STR)
Half-chicane (BSW3+BSW4)
H0/H- dump
BSW3
STR
BSW2
BSW1
Dump
Vacuum pumps
Circulating
p beam
Vacuum pumps
H0/H- monitor
H- beam

6. PSB HST ELEMENTS L4H.BTV.1052 L4H.BCT.1073 L4H.STKR.1052 L4H.BCT.1043
BSW3
BSW4
L4H.BTV.1077
Dump
H0/H- monitor
Diamond BLM

7. Beam Observation System (BTV) with
PSB HST ELEMENTS
L4H.BTV.1052
L4H.BCT.1073
L4H.STKR.1052
L4H.BCT.1043
BSW3
BSW4
L4H.BTV.1077
Dump
Mirrors and
Optical Filters
Stepping motor
Radiation Hard
Camera
H0/H- monitor
Diamond BLM
Beam Observation System (BTV) with
Screen retracted
Loader
Courtesy W. Weterings, R. Noulibos

8. PERMANENT installation:
LINAC4
TEMPORARY installation: HST
Reduce technical and planning risk during LS2 injection system installation
Beam instrumentations, chicane and stripping commissioning
PERMANENT installation:
SF Test Stand (SFTS)
Study of different foil materials, densities, and handling.
Evaluation of foil holder, interlocks, controls, applications..

9. PERMANENT installation:
LINAC4
TEMPORARY installation: HST
Stripping foil
system
Chicane
magnets +
H0/H- dump
Temporary
dump
PERMANENT installation:
SF Test Stand (SFTS)
+ diagnostics, vacuum eq. …

10. OPERATIONS: First beam
INSTALLATION
From July to August 2016: successful summer challenge!
Helped already discovering a few design and fabrication issues, for which mitigation measures were found and implemented
Slight reworking of H0/H- dump (connection issue for H0/H- monitor).
Fabrication issues for BSW undulated vacuum chambers.
Planarity issues of support structure.
Vacuum and connectivity problems with stripping foil system.
Perturbation of the electrical insulation of the chicane magnetic field by supports for vacuum chamber flanges.
OPERATIONS: First beam
protons H-
after
steering
FIRST
BEAM!
L4H.BCT.1043
Downstream SF
TEST STAND: 13th of October 2016
~60 MeV, 100 μs long, -6 mA H-
L4H.BCT.1073
Upstream SF
HST: th of October 2016
160 MeV, 10 μs long, -4.5 mA H-

11. Examples in the next slides
OPERATIONS: Controls and applications
Reduce commissioning time for Linac4 connection
Preparation and improvement of controls and applications
Run Linac4 from the CCC
2 users: MD1 L4 main dump
MD5 HST destination
(MD4 L4 main dump for SFTS measur.)
Cruise Control (A. Akroh)
HST Vistar (Y. Wu)
SEM grid and Wire Scanner (WS) applications (J-F. Comblin)
Trajectories (A. Akroh)
YASP for L4T (J-F. Comblin)
L4T Synoptic (E. Piselli)
Instructions for HST operations (F. Chapuis, G. Guidoboni)
SIS instances for SEM grids and WSs (N. Queneutte) (only check to be done)
Examples in the next slides
Thanks to all PSB and PS operators!
ongoing
ongoing
ongoing

12. OPERATIONS: Controls and applications
CRUISE CONTROL
(CCM: General/Cruise Control)
Pulse length (max=150us per ring)
Prechopper
Pattern per ring:
Chopper Off (beam passing)
Chopper On (no beam)

13. OPERATIONS: Controls and applications
CRUISE CONTROL
(CCM: General/Cruise Control)
Prechopper
100 us
Chopper ON
Chopper OFF
30us
50us
30000
50000
Beam pattern
In Ring4

14. OPERATIONS: Controls and applications
HST Vistar
CCM: General/Cruise Control
User MD1
BCTs in green
H-Negative current
BLMs

15. OPERATIONS: Controls and applications
HST Vistar
CCM: General/Cruise Control
User MD1
protons
Stripping foil

16. temporary HST installation
OPERATIONS: Controls and applications
HST Vistar
CCM: General/Cruise Control
User MD5
L4H sector:
temporary HST installation
Stripping foil

17. OPERATIONS: Controls and applications
Wire scanner:
CCM: Measurements/Wire Scanners
Measurement plane selection
1 application per instrument
Green profile displayed below
Traces selection
Scale in mm wrt the center of the vacuum chamber
Corresponding mean and sigma values
Calibration available only for L4L.BWS.3312 and L4L.BWS.3712

18. OPERATIONS: Controls and applications
SEM Grid application
CCM: Measurements/Chose
1 application per instrument
and plane
Exception: L4L.BSGHV.1173 which has a single attuator for H and V grid.
After selection
Scale in mm wrt the center of the vacuum chamber
Average of all means and sigmas

19. OPERATIONS: SF experience
Improved handling and procedures for stripping foils
Foil breakages (see W.Weterings, Foil breakage history)
BTV screen charging up with beam causing foil breakage when moving? Action: available screen with 15um coating on the back.
To be tested.
Reduce installation/breakage/repair-time in PSB
EXAMPLE: Foil type:ACF 32x68 XCF-200 coated
10 mA beam current

20. OPERATIONS: Instrumentation debugging
H0/H- monitor: Too high noise for BIS interlock.
Actions: new electronics card (~middle of March) and improved FESA class.
SF current monitor: impossible to measure stripping due to escaping electrons (but OK to identify foil breakage).
Possible improvement: collect electrons at the Test Stand with small B field + e- collector
Diamond BLM: signal not observed yet.
BSWs power supply: precision improvements ongoing
BPMs: logged in Timber since the Feb. 23, 2017
Action: new FESA class deployment.
BTV: mechanical movement issue.
Action: solution found and installed at the Test Stand. It will be used for the new installations.
Others: Interlock implementations, chopper patterns, etc…

21. OPERATIONS: Solved issues
Chopping efficiency
L4P.BPM.0707-H
L4T.BPM.0237-H
Unchopped head removed with:
Steering and current lowering (few mA less)
Probable misalignment in LEBT despite intervention during EYETS
Beam instabilities
Horizontal
Position and intensity variation within the pulse Before~5 mm fluctuations
Position instability from pulse-to-pulse
Vertical
L4T.BPM.0237
160 us pulse

22. OPERATIONS: Beam transmission issue
@ TEST STAND
OPERATIONS: Beam transmission issue
L4Z.BCT.0273
SF Test Stand
L4T.BCT.0107
H- Linac4

23. OPERATIONS: Beam transmission issue
@ TEST STAND
OPERATIONS: Beam transmission issue
BCT
H- beam
L4Z.BCT.0273
HST
Transmission
~ 119%
SF Test Stand
NO stripping foil
L4T.BCT.0107
H- Linac4

24. OPERATIONS: Beam transmission issue
@ TEST STAND
OPERATIONS: Beam transmission issue
Positive
= p beam
BCT
H- beam
L4Z.BCT.0273
Transmission
~ -89.8%
(expected
~98%)
SF Test Stand
Stripping foil IN
L4T.BCT.0107
No losses!
Problems:
- SF out: transmission > 100%
- SF in : lower than expected (~98%)
H- Linac4

25. OPERATIONS: Beam transmission issue
@ TEST STAND
OPERATIONS: Beam transmission issue
Attempt of STRIPPING EFFICIENCY measurement
Method: apply correction for >100% transmission (assuming due to diagnostics, tbc!)
Courtesy of C. Bracco.
Corrector current
L4Z.BCT.0273
L4T.RCV.013
SF Test Stand
Results: ~77.5% (theory: ~98%)
same efficiency measured for all foil types (including 2x denser foils)
L4T.BCT.0107
Observations:
Electrons escaping the SF? (BSWs will solve the problem)
Part of H- beam not hitting foil? (neg. current subtracted from pos. p current...)
Losses?
H- Linac4

26. OPERATIONS: Beam transmission issue
@ HST
OPERATIONS: Beam transmission issue
L4H.BCT.1043
L4H.BCT.1073
HST
Dump
SF + BSW3 +BSW4
L4T.BCT.0673
L4T.BCT.0107
H- Linac4

27. OPERATIONS: Beam transmission issue
@ HST
OPERATIONS: Beam transmission issue
L4H.BCT.1043
L4H.BCT.1073
HST
Dump
L4T.BCT.0673
Positive
= p beam
H- beam
Transmission
~104%
L4T.BCT.0107
Stripping foil IN
H- Linac4

28. Transmission issue caused by different sources!
@ HST
OPERATIONS: Beam transmission issue
L4H.BCT.1043
L4H.BCT.1073
HST
Dump
L4T.BCT.0673
Comparison
L4Z.BCT.0273
L4Z.BCT.0273
Current scan from 2.5mA to 9mA
Trans. from 99%-107%
No dependence from pulse length
L4H.BCT.1043
Current scan from 2.6mA to 7.3mA
Trans. from 103%-105%
Pulse length scan from 10 us to 100 us
 Trans from 105% to 107%
SF Test Stand
L4T.BCT.0107
Transmission issue caused by different sources!
Hint fromThibaut Lefevre: similar problems in CTF3 and found out that the diagnostics close to the dump was disturbed by some currents induced by the dumped beam. Grounding problem. (MSWG, March 3, 2017)
H- Linac4

29. OPERATIONS: H0/H- to verify beam steering
Stripping foil Changer
Internal dump
H +
Stripping foil
Orbital Beam H0
H -
H +
H -
1 µm thick carbon foil
(24x68mm)
H0/H- monitor
Courtesy of R. Noulibos, W. Weterings, P. Van Treppen
EDMS

30. OPERATIONS: H0/H- to verify beam steering
No SF and very short pulse (43 turns~393 ns)
BSWs OFF.
If hor. steering is correct, H0L=H0R pulse height on OASIS~950mV
BSWS ON.
If chicane correct, H-L=H-R pulse height on OASIS
With SF and very short pulse (43 turns~393 ns)
BSW ON. If chicane correct, beam centered on L4H.BTV.1077
BSWs OFF
H0L=H0R
H0L
H0R
H-R
H-L

31. OPERATIONS: H0/H- to verify beam steering
No SF and very short pulse (43 turns~393 ns)
BSWs OFF.
If hor. steering is correct, H0L=H0R pulse height on OASIS~950mV
BSWS ON.
If chicane correct, H-L=H-R pulse height on OASIS~1300mV
With SF and very short pulse (43 turns~393 ns)
BSW ON. If chicane correct, beam centered on L4H.BTV.1077~-3mm horizontally
H0L
H0R
H-R
H-L
BSWs ON=3294 A
H-L=H-R

32. OPERATIONS: H0/H- to verify beam steering
No SF and very short pulse (43 turns~393 ns)
BSWs OFF. If hor. steering is correct, H0L=H0R pulse height on OASIS~1000mV
BSWS ON. If chicane correct, H-L=H-R pulse height on OASIS~1300mV
Swapped BSW polarity (-3290A). If chicane correct, beam centered on L4H.BTV.1077
~-3.5 mm horizontally
Reproduced!
H0L
H0R
H-R
H-L
BSWs ON=3290 A
H-L=H-R

33. OPERATIONS: Interesting beam shape
GUMMY BEAR shape?
Maybe from RFQ

34. OPERATIONS: Measurement program
Transmission issue investigation test stand
Steering, different optics, beam profile measurements, check transmission.
Chicane optimization and aperture scans
Measure beam position on screens, losses and H0/H- signals as a function of chicane settings for different optics
Test new version of H0/H- electronics card (ready~mid March)
H0/H- signals calibration (incoming 2 weeks)
Stripping efficiency Test Stand
Measure stripping efficiency
For different foils, with varying beam current, different beam sizes at the foil
Repeat with High Intensity
Solve beam transmission issue + H0/H- calibration
DEADLINE = March 31, 2017
HST dismantling,
Debuncher installation

35. Preparation Reliability Run
RELIABILITY RUN: after the HST
Reliability Run
Preparation Reliability Run
Dismantling of HST beginning of April to install debuncher and missing beam instrumentation
Phase 1: Preparation phase for Reliability Run June-August 2017:
Debuncher commissioning
Finalise Linac4 160 MeV commissioning
Continue RF commissioning/optimization
Phase 2: Linac4 Reliability Run September-December 2017; continuation in 2018 to be clarified

36. Summary and Conclusions
Aim of the Half Sector Test is to test and commissioning the new injection system of the PSB.
Successful in all its phases:
Discovered fabrication issued during the installation phase
Great improvements in controls and application for the reliability run
Good training for handling and procedure for stripping foil exchange
HST commissioning continues until the 31st of March
Solve beam transmission issue
Complete the set of measurements
Stripping efficiency can continue at the SF Test stand (permanent installation)
Thanks to ALL for all the effort and support in all the phases of the HST!
Thanks for your attention!