linac 4, technology choice

122/11/2013 Gerrit Jan Focker, BE/BI/PM

BI review on Radiation development and testing.

Analogue Electronics for:- L4 Grids,

- L4 Scanners,- PS Complex Grids.

Gerrit Jan Focker, BE/BI/PM 222/11/2013

Linac 4, Technology Choice.

Initial design was for Linac 4. 21 Wire-grids at 11 positions, 6 X-Y Wire-scanners. At the time of designing the radiation levels were unknown, but said to be

“high”. Little time for development, production planned right from the start. No choice was given about where to place the equipment. To reach the specifications the electronics should be near the detectors

(Initially 1m80, new design would allow ~8m), i.e. in the tunnel. Therefore we have opted for a system with only the absolutely necessary

electronics near the beamline: Only amplifiers, No logic, Remote power supplies.


PS Complex (excluding L4).

While designing for L4 it was decided that the system could easily be adapted to be used for integrating amplifiers for the PS Complex as well, with different amplifiers.

Standardisation. But: as a result the decision was taken to install this new system in the whole

PS Complex during LS1. 45 Wire-Grids at 33 positions. Very little time for development, the production started before testing with

beam.


Grid System overview.

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

(Twisted-pairs simply because it is available at CERN…) At the PS Complex on many grids (existing) LEMO cables will be used.

Between Amplifiers and Controls a single cable will be used (CERN ND100) mounted with Harting 108-pin connectors.

Power and I/O control are handled by the same ND100 cables, no additional cabling is foreseen.

At Linac 4: Bias +120V directly onto measuring wires. This talk is about the Amplifiers only.

522/11/2013 Gerrit Jan Focker, BE/BI/PM

Amplifier-boxes. Up to 32 channels per Motherboard , 2 Motherboards possible in one 2U chassis. Daughter-boards carrying 4 amplifiers each.


Amplifier Design Details. No electronic switches: miniature reed-relays.

No radiation problems, Galvanic isolation, Low contact resistance, More problems with manufacturing…

The amplifiers cannot consume too much power, Power: losses over 200m cable. By reducing heat in chassis we hope to increase lifetime.

Input-protection by small-signal diodes BAV199 and zener-diode(s) BZX84Cxx. Amplifiers AD8610ARZ, AD8032ARZ and AD8397ARZ,

All from Analog Devices XFCB process, (Not that many alternatives anyway…)

Report from the European Space Agency and NASA: “Commercial Components Identification In Naturally Radiation Hardened Technologies”

2002ESASP.507...17M Chips from this family that were tested were still o.k. after 100kRad(Si) radiation. It is claimed that these chips appear not to suffer from single event upset.

But a remote control of the Power Supplies is foreseen.


Linear Amplifier for Linac’s (1).

Amplifier’s Maximum Electrical Input: 10mA, Amplifier’s highest sensitivity: 1μA full scale,

The calculated input-related noise-level is ~2nA at 1MHz BW. Overall BW is mainly defined by the cable-length between grid and

electronics, The newer design allows cables up to 8m.

Isolated input-stage: Bias of up to +120V on measuring wires (Linac 4). Isolated input-stage avoids large input-capacitors.

The design includes the use of test-resistances: At the amplifier-inputs. Outside the vacuum-chamber at the cable-connection, At the grid in the vacuum-chamber, (Only applied at the new L4 grids and Scanners).


Linear Amplifier for Linac’s (2)


Linear Amplifier for Linac’s(3).


Scanner Amplifier (L4).

For the Scanners the same linear amplifiers are used as for the Linac SEM-Grids. Same 4-channel Amplifier boards.

Grids have many wires: If a channel dies one will still have a picture.

Redundancy for the scanners: Two Amplifiers are connected to each wire, Each channel is doubled from beginning to the end and uses two

ADC channels.


Scanner Amplifier input.


Integrating Amplifier for circular machines (1).

Amplifier’s Maximum Electrical Input: 250nC, Amplifier’s highest sensitivity: 2,5pC full scale,

The sensitivity appears to be limited mainly due to instabilities from the Power Supply (quite variable, 25fC ???).

Cable-length between grid and electronics defines noise and speed of the Amplifiers,

Some cables up to 20m, For reliable measurement of the short pulses at TT2: length should be < 3m.

Test-resistances: Only at the amplifier-inputs. Grids and cabling would have to be rebuilt for others tests.

Two input circuits: Active integrator for charges up to 2,5nC, Passive integrator for higher charges. The active integrator should be able to withstand a pulse of at least 250nC !


Integrating Amplifier (2)


Placement of the electronics in the tunnels.

L3, PS inflection zone , Booster BTM, LEIR, TT2 and most of the L4: Underneath or close to the Beamlines.

Help from the Radiation-to-Electronics Team (Joao), L4: Define a position close to the Dump for a small Rack and

protection. PS and Inflection zone,

PS position 42 to 56: use the gap next to the support girder like Jeroen does.

Inflection zone: just move some electronics out of the way. Cable-lengths:

Linac’s linear amplifiers: up to 8m. Integrating amplifiers (not TT2): more than 8m degrades signal. TT2: shorter than 3m.

Gerrit Jan Focker, Jean Tassan-Viol, BE/BI/PM 1822/11/2013

Place in the Linac 4 tunnel (1)Emplacement Type de montage Type de capteur Position

LEBT Montage sur la poutre SEM grid 2 x 24 wires L4L.BSGH.1151 L4L.BSGV.1151

Chopper line Montage sur la poutre 2 Wire scanners L4L.BWS.3312 L4L.BWS.3712

DTL Rien Rien

CCDTL Au sol SEM grid 2 x 24 wires L4C.BSGH.0121 L4C.BSGV.0121

CCDTL Au sol Wire scanner L4C.BWS.02112

CCDTL Au sol SEM grid 2 x 24 wires L4C.BSGH.0421 L4C.BSGV.0421

CCDTL Au sol Wire scanner L4C.BWS.0622

PIMS Au sol SEM grid 2 x 24 wires L4P.BSGH.0121 L4P.BSGV.0121

PIMS Au mur, on a 75cm Wire scanner L4P.BWS.0402

PIMS Au mur , on a 75cm SEM grid 2 x 24 wires L4P.BSGH.0601 L4P.BSGV.0601

PIMS Au mur , on a 75cm Wire scanner L4P.BWS.1002

Au sol SEM grid 2 x 24 wires L4T.BSGH.0223 L4T.BSGV.0223

Juste avant ligne dump Rien BSM

Rack SEM grid 2 x 24 wires L4T.BSGH.0243 L4T.BSGV.0243

Ligne dump Rack SEM grid 2 x 24 wires L4Z.BSGH.0273 L4Z.BSGV.0273

Ligne dump Rack SEM grid 2 x 24 wires L4Z.BSGH.0287 L4Z.BSGV.0287

Virage Rack SEM grid 2 x 24 wires L4T.BSGH.0523 L4T.BSGV.0523

L4T Au sol SEM grid 2 x 24 wires L4T.BSGH.1247 L4T.BSGV.1247

1922/11/2013 Joao Pedro De Carvalho Saraiva, Jean Tassan-Viol, Gerrit Jan Focker, BE/BI/PM

Place in the Linac 4 tunnel (2)

Original slides from Joao Pedro De Carvalho Saraiva, EN/STI/EET

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CPS Radiation levels

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22/11/2013 Original slides from Joao Pedro De Carvalho Saraiva, EN/STI/EET


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Conclusions.

Little choice of chips suiting our requirements, From the chips we found at least the family characteristics seem

to allow to use them in a somewhat radioactive environment. No radiation tests done. If done, they would always have been

afterwards… Thanks to R2E for the great job finding reasonable positions in the

tunnels!

linac 4, technology choice

Documents

amplifiers ad8610arz

manufacturingthe amplifiers

different amplifiers

ps complex grids

l4 grids

radiation development

amplifiers highest sensitivity

radiation problems