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BE-BI-PM Section

LINAC4 Test Bench at 3 and 12 MeV

In visage of the LINAC 4 commissioning, a movable test bench setup is at first foreseen in a laboratory hall and and later in the LINAC4 tunnel.

During 3 commissioning stages the bench, equipped with several instruments for longitudinal and transverse diagnostics, will be plugged at the exit of the Linac4 front end and first DTL tank:

StageLast L4 elementH- EnergySchedule
1RFQ3 MeV2011
2Chopper Line (MEBT)3 MeV 
3DTL112 MeV 

The following systems are required for beam transverse profile and emittance measurements:


Design in progress

2-SEM grid in the straight line

H- Energy3 MeV and 12 MeV
SEM Gridphysically the same as the one
used at the source emittnace meter, slit will change
MovementStepping Motor
# of Wires40 (48 ADC channels)
Wire Materialproposal:
Carbon at 3 MeV
Tungsten at 12 MeV
Wire diameter 
Wire distance0.75 mm (desired resolution for small beams at 12 MeV
achievable by 'microscans' of SEM grid at each SLIT Position)
DrawingsCCD Folder
Assembly (pdf)

3-SEM grid in the spectrometer line

SEM grid

H- Energy3 MeV and 12 MeV
SEM Grid Need to produce new frames, new mechanism
# of Wiresproposal: 48
Wire Materialproposal:
Carbon at 3 MeV
Tungsten at 12 MeV
Wire diameterproposal:
Carbon wires 34 um
Tungsten wires xx um
Wire distanceproposal: 12 at 1mm, 24(central) at 0.5mm, 12 at 1mm = 48

The complete list of needed systems (not only beam profile and emittance) is discussed in G.Bellodi, USER SPECIFICATIONS FOR LINAC4 TEST BENCH DIAGNOSTICS and can be summarized as follows:

Instrument/systemAimRequirements / CommentsLinks
Slit / Grid systemsTransverse EmittanceAll nominal commissioning beam types-SLIT-GRID system
-Beam par. @ slit
Halo Monitor (transverse)Beam quality, Matching between structures -M.Hori, Spatial and time beam profile monitor with nanosecond resolution for the Linac4 testbench
Feschenko monitorLongitudinal (and transverse?) bunch shapeCritical to assess chopping efficiency-R.Scrivens,The Feschenko Bunch Shape Monitor, User Experience at CERN
Beam Current Transformers   
Beam Position Monitors   

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Page last modified on May 05, 2010, at 12:35 PM EST