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Proposal for the Barrel Alignment Upgrade. Bencze György, Béni Noémi, Szillási Zoltán , Ujvári Balázs. (ATOMKI, RMKI ). the Hardware Barrel Alignment Group. This project is supported by Hungarian Research Fund (OTKA) NK 81447. Outline. Two bigger topics:.

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Proposal for the barrel alignment upgrade

Proposal for the Barrel Alignment Upgrade

Bencze György, Béni Noémi, Szillási Zoltán, Ujvári Balázs


the Hardware Barrel Alignment Group

This project is supported by Hungarian Research Fund (OTKA) NK 81447 .


Two bigger topics:

  • Reinforcement of measurements in Sector 13 & 14

  • Measurement of inter-wheel distances within Barrel

Two minor items:

  • Additional PG targets/redesign PG targets on MABs

  • Programming extension to BoardPCs

And a wish…

  • Incorporate DT temperatures into the Ali reco

Barrel Alignment – Upgrade proposal 2

Reinforcement of alignment measurements in sector 13 14
Reinforcement of alignment measurements in Sector 13 & 14

Barrel Alignment – Upgrade proposal 3

Proposal for the barrel alignment upgrade







plane (6)

Muon chamber

optical line

Z bar

(8 lines)


(36 pieces)

Link line

Schematicview of the Barrel Alignment


muon chambers


light sources (LED)

  • - Rigid structures (MABs, z-bars)

  • Video-camera boxes (on the MABs)

  • LED holders (called forks,

  • on the chambers)

  • Diagonal and Z-LED holders

  • (on the MABs and Z-bars)

  • - Board computers (one for each MAB)

Barrel Alignment – Upgrade proposal 4

Sectors 13 14 for mb4 chambers
Sectors 13-14 for MB4 chambers

Sector 13

Sector 4

Sectors 4 and 10 are measured at the –phi side only (by 4 MABs)

Chambers in sectors 13 and 14 are measured at the +phi side only (by 2 MABs)


Sector 10

Sector 14

Barrel Alignment – Upgrade proposal 5

Results what is expected
Results – what is expected

What is measured (sect 13,14):






Measurement point





Transversal view

Longitudinal view

What is expected:

Fair results in X and Z at MB+/-1,2, weak in rot_Z, therefore also in Y (depending on the chamber orientation), very weak in general for YB0.

Barrel Alignment – Upgrade proposal 6

Results cocoa error study
Results – COCOA-error study

Mean and Max errors (COCOA-errors only but real measurement data):

Mean Max

In X (all chambers, micrometer) 26 61

In Z (YB0 excluded, micrometer) 23 34

In rot_Z (YB0 excluded, mrad) 1.9 2.0

Other rotations (all chambers): <0.3 mrad

For YB0:

In X: 61 micrometer; In Z: 2770 micrometer(!) In rot_Z: 13 mrad (!)

As expected but here we have the numbers

Barrel Alignment – Upgrade proposal 7

The proposal
The proposal

Put a MiniMAB with 2 cameras at the joint region looking inside the wheel.

The cameras can observe the LEDs (already installed but not used so far).

The MiniMABs can fix the DTs wrt. each other.






Proposed MiniMAB


Sector 4

Sector 13



Sector 10

Sector 14

Barrel Alignment – Upgrade proposal 8


Cameras identical to those used for chimney-chamber regions

Two types:

top and bottom


Carbon-fiber plate (5mm thickness)

Camera distance „d”:

Sector 13 Sector 14

(top) (bottom)

368 mm 457.4 mm

Barrel Alignment – Upgrade proposal 9

Results of simulations sectors 4 and 13
Results of simulations, sectors 4 and 13



Barrel Alignment – Upgrade proposal 10

Results of simulations sectors 10 and 14
Results of simulations, sectors 10 and 14



Barrel Alignment – Upgrade proposal 11

What is needed
What is needed

18 carbon-fiber plates to be bought (cheap)

36 video-sensors available from spares

36 lenses from spares (f=20mm)

36 camera-houses to be fabricated

4 board-PCs from spares*

2 CAEN A3006 LV modules to be bought (~12kCHF)

2 power distrib.+eth.switch parts (switch,

connectors, box) to be

bought, assembly needed

In addition:

Camera-box assembly, calibration

MiniMAB calibration

Cabling, installation

Installation is possible during the next long shut-down when the barrel is opened.

Free spaces for LV modules and 1U distrib. modules are OK

* New BPC are to be installed only on YB±1. Otherwise use free ports of existing ones.

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Measurement of inter wheel distances within barrel
Measurement of inter-wheel distances within Barrel

Barrel Alignment – Upgrade proposal 13


  • measurement of the distance between the barrel wheels is desireable during closure and magnet ramp

  • more sensor could also show wheel deformation (some hints from Barel Ali)

Easiest solution is to put distance meters on the wheels and read them out through the BoardPC. (since it would require the least cabling work)

Barrel Alignment – Upgrade proposal 14

Possible solutions
Possible solutions

  • Laser displacement sensor:

  • quite expensive

  • needs digital

  • Voltage should be compatible with MAB, BPC


Sticks out -- vulnerable

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Possible solutions1
Possible solutions

  • device used by EndCap Ali is an analog one (and no more produced)

  • digital one needed (from different firm)(possible some serial comm, since PBC still has one free RS232 port)

  • candidate: Micro Epsilon (RS422)

  • firm has been contacted for technical & pricing details --- had an on-site meeting

  • whenknowthepricewecoulddiscusshowmanysensorswewant

  • can start magnetic & radhardtests

  • Mimmocan design mounting

≥ 1300 CHF/pc !!!

Barrel Alignment – Upgrade proposal 16

Where to install
Where to install

MAB volume (or close to it) is a good candidate

  • only local cabling needed

  • wheel ref holes are close and could be used

  • Ref holes have very good surface and

  • used by Survey to define wheel  possibility to follow wheel movements in survey approach

Barrel Alignment – Upgrade proposal 17


  • enormous number of devices would be needed for accurate wheel position/deformation measurements

 Min 50kCHF (or rather above)

  • since Ali doesn’t have wheels (DTs only), these measurements would not improve

  • these devices are not good for closing either…

We propose to abandon this project

To tell the truth, we plan to be involved in a similar closing sensor, but:

  • less precise (~1-2 mm)

  • much less number

  • not radhard, not B tolerant

  • cheaper (HOPE!!!)

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Additional pg targets redesign pg targets on mabs
Additional PG targets/redesign PG targets on MABs

Barrel Alignment – Upgrade proposal 19


This is a minor item, but having large impact…

  • there is a discrepancy between the track and the hw alignments both in Z (2mm, scaling?) and phi-like torsion (3mm)

  • so far we have only indirect ways to test where it comes from

  • previous item wouldn’t solve this enigma, since Barrel Ali doesn’t have wheels.

  • torsion has gone, but was not solved by us! We need a direct external measurement possibility.

Barrel Alignment – Upgrade proposal 20

What to do
What to do?

It would be nice to measure all 6 dof of a MAB, but it is impossible  measure at least one point of it:


These points are surely seen from outside

Barrel Alignment – Upgrade proposal 21

What to do with them how
What to do with them? How?

  • Survey group could measure Z coordinates of them (or at least Z distance)

  • Antje says precision is around 70 microns (discrepancy, we have ~ 2mm!)

  • Maybe they can measure phi position as well  answer for torsion…

  • If Z scaling found, its value can be used as a correction later.

  • Solution is cheap

  • Mimmo can design (probably the worn MAB definition targets are also to be changed at the same time)

  • New targets are needed to be located inside the MABs frame  needs access to them and probably to be done in ISR.

Barrel Alignment – Upgrade proposal 22

Programming extension to boardpcs
Programming extension to BoardPCs

Barrel Alignment – Upgrade proposal 23

Motivation and the solution
Motivation and the solution

  • In last May we lost a Custom Board since its software got frozen

  • Problem is known, it is due to a bootloader that is designed to be able to upload new firmware if needed

  • Now, on 30 (out of 36) Custom Boards, bootloader is disabled (May problem happened on one of the remaining 6)

  • This prevents us from uploading new firmware…


We would like to design and install a small device on BPC to solve it

This item is very small, but also requires access to MABs…

Barrel Alignment – Upgrade proposal 24

And finally a wish
And finally a wish…

Barrel Alignment – Upgrade proposal 25

Use t dt in ali reco
Use TDT in Ali reco

DT Calibration in ISR…

  • DT temperature varied between 19 and 24 degC

  • We have this data for all DTs

Barrel Alignment – Upgrade proposal 26

Use t dt in ali reco1
Use TDT in Ali reco

Alignment measurements in UXC…

  • Temperature on MABs varies between 19 and 26 degC

  • This is the T of air and not DT

Tmeas ≠ Tcalib distance of alignment passages change  APE gets worse

(αAl = 23.1 μm/K  …might be 100 μm/K on MB4!!)

Barrel Alignment – Upgrade proposal 27

Use t dt in ali reco2
Use TDT in Ali reco

Latest APE calculations σXlocal ~ 500μm (wrt. PG)

We belive that APE could be reduced if actual chamber temperature could be used.

(αAl = 23.1 μm/K  …might be 100 μm/K on MB4)

  • This would require to measure rather the real DT temperature than the air (MAB).

  • Measure the gas temperature? At the manifold on the chamber exit?

  • Aachen has a proposal for that.

Barrel Alignment – Upgrade proposal 28


We have four items and would like to get the consent of the DT:

  • Reinforcement of measurementsinSector 13 & 14

  • Measurement of inter-wheeldistanceswithin Barrel

  • Additional PG targets/redesignPGtargetsonMABs

  • ProgrammingextensiontoBoardPCs

  • Use TDTin Ali reco

Institutes could be involved:


  • Budapest

  • Univ of Debrecen

  • CERN ?

  • Torino (Mimmo)

  • Aachen (TDT)

Probably all of these modifications could be made in 2013.

Barrel Alignment – Upgrade proposal 29