Linac4 grids and bws
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Linac4 Grids and BWS. Technology Choice. Existing electronics is very old, uses old components, demands a lot of maintenance and pcb’s would need to be redesigned anyway. Though the intensity is unknown, a high level of radiation is expected.

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Linac4 Grids and BWS

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Linac4 grids and bws

Linac4 Grids and BWS

Gerrit Jan Focker, BE/BI/PM


Technology choice

Technology Choice.

  • Existing electronics is very old, uses old components, demands a lot of maintenance and pcb’s would need to be redesigned anyway.

  • Though the intensity is unknown, a high level of radiation is expected.

  • Therefore we have opted for a system with only the absolutely necessary electronics near the beamline:

    • Only amplifiers,

    • No logic,

    • No power supplies.

Gerrit Jan Focker, BE/BI/PM


Grid overview

Grid overview.

  • Between Grid and Amplifier: two cables with twisted pairs with individualscreening. The two cables will be mounted together in Harting 72-pin connectors.

  • Between Amplifiers and Controls a single cable is proposed (CERN ND100) mounted with Harting 108-pin connectors.

  • Power and I/O control are handled by the same cables, no additional cabling is foreseen.

  • Bias +120V directly onto measuring wires.

Gerrit Jan Focker, BE/BI/PM


Amplifier boxes

Amplifier-boxes

  • Up to 32 channels per box. (ADC’s are 36-channel)

  • Motherboard with daughter-boards carrying 4 amplifiers each.

    • Amplifiers with BW = ~1MHz for Linac4,

    • Input amplifiers can be floating at up to +120V (bias).

  • The amplifier box will pass the signals for the I/O control.

Gerrit Jan Focker, BE/BI/PM


Controls of grids

Controls of grids.

  • VME-crates:

    • 20 ADC’s divided over 2 crates,

    • Sampling at max. 250kHz,

    • Serial RS422 Control cards, CO-standard.

    • Card for Trigger?

  • 3 Interface chassis, each containing :

    • Up to 8 controller cards

      • Limitation of 8 due to the size of the Harting connectors.

    • 24V power.

Gerrit Jan Focker, BE/BI/PM


Grid controller cards

Grid controller cards.

  • Automatic offset-zeroing,

  • Software controlled MUX: output to OASIS,

  • +5V power for Amplifier output stages,

  • Floating +5V power at max. +120V for Amplifier input stages (bias),

  • Pneumatic Movement control,

  • Control of relays for amplification setting and test-signals.

  • Control by RS422.

Gerrit Jan Focker, BE/BI/PM


Linac4 grids and bws

BWS.

  • No Encoder, only precision switch.

  • Controlled from the second SEM-grid VME crate,

    • 2 ADC’s.

  • One amplifier card per scanner,

    • The amplifier cards are designed so that two amplifiers can be connected to each single input for redundancy.

  • Use the same control card as SEM-grids (Only 4 channels used).

Gerrit Jan Focker, BE/BI/PM


Linac4 amplifier

Linac4 Amplifier

Gerrit Jan Focker, BE/BI/PM


Amplifier part control card

Amplifier Part Control card.

Gerrit Jan Focker, BE/BI/PM


Design details

Design Details.

  • Amplifier’s Maximum Electrical Input: 10mA,

  • Amplifier’s highest sensitivity: 1μA full scale,

    • The calculated input-related noise-level is ~2nA at 1MHz BW.

    • With software amplification highest sensitivity will be (=<)200nA full scale.

  • Overall BW is defined by the cable-length between grid and electronics,

    • At highest sensitivity the BW is 275kHz for 1,5m cable, 210kHz with 2m cable,

    • At 10μA full scale BW will be ten times higher.

  • Low frequency cut-off: 500Hz.

  • Isolated input-stage: Bias of up to +120V on measuring wires.

  • The design foresees to use test-resistances:

    • At the grid in the vacuum-chamber,

    • Outside the vacuum-chamber at the cable-connection,

    • At the amplifier-inputs.

  • The design is made to accept different amplifier cards so it can be used for other machines as well.

Gerrit Jan Focker, BE/BI/PM


Status

Status.

  • All Electronics parts have been ordered (for complete series and spares).

  • All parts are expected before end October.

  • PC-board prototypes expected second week of November.

  • Cables in the tunnel are being installed.

  • At the moment the most important is to get a system running at the Linac4 test-stand.

    • For this a pre-series of amplifier cards must be made after the prototype has been verified. February??

    • The cable has to be adapted to the existing grid, which will necessitate mechanical work.

    • Software must be written.

Gerrit Jan Focker, BE/BI/PM


Conclusions and remarks

Conclusions and remarks.

  • This system can also be used for other machines by using different Amplifiers. The “Control-card” has been designed to suit these different applications.

  • BWS: At this stage the detailed design of the connecting parts is being finalised.

  • BWS: a temporary setup is being installed at the test-stand, using old amplifiers.

Gerrit Jan Focker, BE/BI/PM


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