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

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

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

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

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

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

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

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..

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. …

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: 26th of October 2016 160 MeV, 10 μs long, -4.5 mA H-

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

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)

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

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

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

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

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

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

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

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…

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

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

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

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

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

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

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

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

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 1370573

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

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

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

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

OPERATIONS: Measurement program Transmission issue investigation (@SF test stand and @HST) Steering, different optics, beam profile measurements, check transmission. Chicane optimization and aperture scans (@HST) 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 (@SF Test Stand and @HST) 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

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

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!