Linac 4 Instrumentation K.Hanke CERN

Linac 4 Instrumentation K.Hanke CERN

CERN Linac 4 PS2 (2016?) SPL (2015?) Linac4 (2012) Linac4 will first inject into the PSB and then can be the first element of a new LHC injector chain. It will increase the beam brightness for the LHC, provide more beam to ISOLDE, increase the reliability.

CERN Linac 4 Overview 95 kev 3 MeV 3 MeV 50 MeV 100 MeV 160 MeV )/,-.!)*%%+, "#$!!"#$ %&'( RF volume source (DESY) 35 kv extrac. +60kV postacc. Radio Frequency Quadrupole (IPHI) 352 MHz 6 m 1 klystron 1 MW Chopper 352 MHz 3.6 m 11 em quad 3 cavities Drift Tube Linac 352 MHz 18.7 m 3 tanks 3 klystrons 4 MW 82 pm quad Cell-Coupled Drift Tube Linac 352 MHz 21 m 21 tanks 7 klystrons 7 MW 21 em quads Pi-mode structure 352 MHz 22 m 12 tanks 6 klystrons ~12 MW 12 em quads total linac 4: 80 m, 18 klystrons ion current: 40 ma (avg. in pulse), 65 ma (bunch) RF duty cycle: 0.1% phase 1 (Linac4) 3-4% phase 2 (SPL) (design: 10%) 4 different structures, (RFQ, DTL, CCDTL, PIMS) re-design w.r.t. TDR after review May 2007

Source & LEBT - emittance scanner - spectrometer - fixed Faraday cup - transformer diagnostics box (Faraday cup, SEM)

Source & LEBT instrument position energy [MeV] intensity resolution [ma] retractable Faraday cup between solenoids 0.095 80 0.1 ma fixed Faraday cup before RFQ 0.095 80 0.1 ma SEM grid between 0.095 80 2 mm solenoids SEM grid after 0.095 80 1 mm spectrometer transformer 0.095 80 1 ma emittance movable 0.095 80 1 mrad

Faraday Cup Design for LEBT bias ring, collector and housing made of st. steel vespel insulators for electrical isolation conical collector use of metal seals only flanged high voltage feedthrough flanged signal feedthrough linear pneumatic drive (travel 102mm) flange DN150CF (ø outer 202mm) C.BAL

Chopper Line 2 slow wire scanners BSHM 2 transformers

Chopper Line instrument position energy [MeV] intensity resolution [ma] slow wire upstream and 3.0 80 0.1 mm scanners downstream of chopper transformer between first two and last two quads 3.0 80 0.5 ma beam shape and halo monitor end of chopper line 3.0 80 1 ns 1 mm

Chopper Line Transformers

Chopper Line Transformers Magnetic Shielding

Chopper Line Transformers Microwave Studio Simulation

Chopper Line Slow Wire Scanners horizontal and vertical measurement slow movement (not single-shot) wide moving range allows to measure deflected and undeflected beam after chopping

Halo Monitor Specifications 2.84 ns ~10 3 ions ~10 8 ions 1st objective: measure residual H - in (not completely) chopped bunches with a sensitivity of ~ 1000 ions, in the vicinity of full bunches (~10 8 ions). detector must be turned on/off within 1 ns, dynamic range 1:10 6 2nd objective: transverse imaging, halo diagnostics beam core: ~10 8 H - /bunch/cm 2 beam halo: ~10 3 H - /bunch/cm 2 active area of detector 4 4 cm dynamic range: 1:10 6

Halo Monitor Principle carbon foil e - H - grids phosphor screen fibre optics bundle CCD camera

Halo Monitor View Inside carbon foil grids H - e - light guide

Halo Monitor Light Guide and Camera grids fibre optics bundle CCD camera

Halo Monitor Light Guide and Camera light guide active area 50 mm Ø 50 million fibers magnification 1.8 provides shielding against X-rays and neutrons CCD camera UHV compatible 1300 x 1300 pixels

Halo Monitor Overall Set-up

Halo Monitor Tests with Laser Beam M.HORI longitudinal measurement: < 2 ns timing resolution achieved transverse imaging: FWHM <5 mm image observed for 4 mm input beam mm-scale resolution achieved beam time approved for test at TANDEM/ALTO facility (Orsay)

3 MeV Test Place IPHI diagnostic line 3 MeV test place in the PS South Hall including source, LEBT, RFQ, chopper line and IPHI diagnostic line

IPHI Measurement Line A.C.C.T. R.F.Q. Pick up Dipole magnet Quadrupoles magnets Pump Wire scanner D.C.C.T. Steerer B.P.M. CCD cameras B.P.M. B.P.M Beam stopper Pumps intensity measurement: 1 D.C.C.T et 1 A.C.C.T beam position measurement: 6 P.U. energy measurement: 3 P.U. energy spread measurement: 2 slits + 1 F.C. transverse profiles: 1 wire scanner, optical measurements, backscattered protons temperature measurements of the beam pipe Patrick AUSSET - Meeting SPL / IPHI June 7th-8th - 2007

DTL Overview SEM grid beam current transformer BLM beam loss monitor wire scanner position, intensity and phase pick-up BLM BLM DTL tank1 DTL tank2 DTL tank3

DTL Commissioning commissioning phase: moveable bench for different stages of the DTL Faraday Cup, SEM grid, transverse and longitudinal emittance diagnostics, 2 pick-ups (time-of-flight), energy degrader + Faraday cup - for DTL tank-by-tank commissioning - SNS experience with D-Plate

Bunch Length Monitor transformation of longitudinal bunch structure into a transverse distribution of secondary electrons consists of a wire in which secondary electrons are created an electric field to accelerate the electrons deflecting plates with a deflecting field synchronous with the accelerator RF an electron detector detector mainly developed by Institute for Nuclear Research (INR) Moscow (A. Feschenko and collaborators) INR is willing to build detectors for us

DTL Diagnostics Summary instrument position energy [MeV] intensity [ma] resolution pick-up (phase, position, intensity) after every tank 12/32/50 40 0.1 deg 0.1 mm 0.5 ma SEM grid after tank 3 50 40 0.5 mm transformer after tank 3 50 40 0.5 ma

Phase/Position/Intensity Pick-Ups to be measured: absolute beam position with respect to an external reference. relative beam intensity measured by two consecutive pick-ups. absolute beam intensity after calibration with BCT. absolute beam phase with respect to distributed RF reference. time of flight between two pick-ups. limited longitudinal space: integrated design for quadrupole, steerer and pick-up 250mm are needed for magnet and pick-up in CCDTL and SCL

CCDTL Modules 1-4 SEM grid beam current transformer BLM beam loss monitor wire scanner position, intensity and phase pick-up CCDTL module1 BLM CCDTL module2 BLM CCDTL module3 CCDTL module4

CCDTL Modules 5-7 SEM grid beam current transformer BLM beam loss monitor wire scanner position, intensity and phase pick-up CCDTL module5 BLM CCDTL module6 BLM CCDTL module7

CCDTL Summary instrument position energy [MeV] intensity [ma] resolution pick-up (phase, position, intensity) after every module 57/64/72/79/ 86/94/100 40 0.1 deg 0.1 mm 0.5 ma SEM grid after modules 4 and 7 79/100 40 0.5 mm wire scanner after every module 57/64/72/79/ 86/94/100 40 0.1 mm transformer after module 7 100 40 0.5 ma

PIMS SEM grid beam current transformer BLM beam loss monitor wire scanner position, intensity and phase pick-up BLM cav 1 cav 2 cav 3 cav 4 cav 5 cav 6 BLM cav 7 cav 8 cav 9 cav 10 cav 11 cav 12

PIMS Summary instrument position energy [MeV] intensity [ma] resolution pick-up (phase, position, intensity) after every other cavity 110/120/129/ 139/149/160 40 0.1 deg 0.1 mm 0.5 ma SEM grid after cavities 6 and 12 129/160 40 0.5 mm wire scanner after cavities 3 and 9 40 0.1 mm transformer end of linac 160 40 0.5 ma

Summary o think about commissioning strategy from the beginning commissioning vs operation; what diagnostics is needed in order to commission the linac (e.g. set rf phase), at what stage of the installation, which diagnostics is suitable for which energy - what is needed in day-to-day operation o steerers steerers are essential closeley linked to diagnostics (pick-up number and position) beam dynamics study to minimise beam loss define steerers define diagnostics overall linac lay-out ( free space vs beam dynamics) everything is linked o space constraints integrated design of quadrupoles, steerers and pick-ups o beam loss is an essential issue (longitudinal and transverse halo, steering) dedicated diagnostics; interlocks based on transformers and BLMs ( watchdog ) o high beam power can damage diagnostics non-intercepting diagnostics where possible; different modes of operation, e.g. diagnostics/commissioning beams with reduced macropulse length