118/10/2011 Gerrit Jan Focker, BE/BI/PM

Linac4 Grids and BWS

Gerrit Jan Focker, BE/BI/PM 218/10/2011

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 318/10/2011

Grid overview.

Between Grid and Amplifier: two cables with twisted pairs with individual screening. 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.

418/10/2011 Gerrit Jan Focker, BE/BI/PM

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 518/10/2011

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 618/10/2011

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 718/10/2011

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 818/10/2011

Linac4 Amplifier

Gerrit Jan Focker, BE/BI/PM 918/10/2011

Amplifier Part Control card.

Gerrit Jan Focker, BE/BI/PM 1018/10/2011

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 1118/10/2011

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 1218/10/2011

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.