CDCH2019 reopening

Marco Chiappini & Gianluigi Chiarello

Tokyo MEG meeting

19 March 2019

➢ CDCH removal operations from πE5 area ✔• Endcaps disassembling in the barrack ✔

➢ PSI OST cleanroom preparation ✔• Assembly tools shipping to PSI ✔

➢ Reopening operations ✔• Geometry survey before reopening ✔

➢ Broken wires removal ✔• First investigations ✔

➢ Extra-stretching… next step➢ Conclusions

Outline @ January 2019 meeting

1/22

RDC removal

2/22

➢ RDC removal on 24/01/2019• DS signal cables unplugging

from the crates and unroutingup to the support rail

• Half of the cables pass through one of the hole in RDC support structure

• Temporary cables arrangement in a higher position to allow DS TC extraction without mechanical conflicts

CW insertion system

dismantled

First look inside the inner volume

to check the mylar foil and target OK

DS TC extraction

3/22

➢ DS TC safely extracted on 24/01/2019• Extraction trolley with rails to slide TC

out of COBRA• Unrouting of TC cables under COBRA

➢ No CDCH-TC mechanical conflicts with signal cables in higher position

➢ We need to optimize this point for the future

➢ Water removal from DS and US cooling pipes➢ Disconnection of DS gas and cooling pipes➢ From now on the wires volume is kept

isolated with He inside

DS signal uncabling

4/22

➢ DS signal uncabling on 24/01/2019• After RDC-TC removals to avoid the uncomfortable

positions experienced during the last signal cabling• Much faster operation• After the removal of the 3D-printed endcovers screwed

to CDCH extensions used for cables fixation

BEFORE AFTER

BTS removal

5/22

➢ BTS removal on 30/01/2019• US signal cables

unplugging from the crates and unrouting up to the support rail

• Temporary cables arrangement to allow the removal of the BTS-CDCH connection

➢ Lifting moment with the main crane of the Experimental Hall

➢ Then collision accident to the Joule-Thompson tower

➢ Already repaired

US signal uncabling

6/22

➢ US signal uncabling on 30/01/2019• After BTS removal• Much faster operation• After the removal of the 3D-printed endcovers

➢ Disconnection of US gas and cooling pipes

➢ We also disconnected the HV cables from the 2 patch panels and temporarily arranged them inside the endcap to allow an easier CDCH extraction

➢ On 31/01/2019• Removal of the

connection flange with service feedthroughs(target movement, COBRA volume gas inlets) between CDCH inner US extension and BTS

• Removal of the target + monitoring cameras

BEFORE

AFTER

CDCH extraction

7/22

➢ CDCH extraction on 01/02/2019➢ Then CDCH was immediately

transported outside 𝛑𝐄𝟓 area with the main crane and put temporarily inside the barrack

1

2

3

Rail extraction and CDCH laid down on

the transport trolley

CDCH safely extracted from COBRA sliding on a trolley with wheels

Extraction rail inside

the COBRA volume

Link to videoclipof flying CDCH

Link to videoclipof CDCH

extraction

CDCH in the barrack

8/22

➢ CDCH endcaps disassembling in the week 4-8/02/2019• CF extensions• 432 FE cards (216 with HV cables)

o All the cards sent to Lecce to be tested (test ongoing)

o Found a lateral feedback resistor damaged in 30 cards

o Already repaired in Lecceo This requires a manual machining of

the FE cards holders to avoid future damages

➢ Cut of the ThreeBond glue all around the inner part of both endplates OK

➢ Then inner extensions removal

1

2

3

• Service pipes and FE cards holders

Material transport to PSI

➢ As scheduled the transport of the tools for CDCH assembly was done on 12/02/2019

➢ Used two vans for about 1 ton of material in total

Central shaft, cradle structure with rails, big support structure for axis insertion/extraction, reference base

for CDCH assembly, broken wires extraction tool, dehumidifier and other auxiliary tools…

➢ Max ≈ 𝟏𝟎𝟎𝟎 particles/𝐟𝐭𝟑

with dimension ≥ 𝟎. 𝟓 𝛍𝐦➢ Performance confirmed

with particulate counting measurements with all the material inside 9/22

PSI cleanroom preparation

➢ 90 mm-Bosch profiles structure with concrete pillars to replace the granite table we had in Pisa

➢ Adjustable height: big screw with fine thread and locknut

➢ Spherical joint between the head of the screw and the table

Support structure to hold the central shaft in

a cantilever position aligned with the cradle

structure which can slide on rails to reinsert

the axis inside CDCH

➢ Movable crane with chain hoist• Max load capacity

500 Kg➢ CDCH/heavy stuff

handling10/22

➢ 25-26/02/2019 for cleanroom preparation

CDCH WEST-OST transport

11/22

➢ CDCH transport from the Experimental Hall to the cleanroom on 27/02/2019

➢ We exploited this special trailer towed by a Defender with ground load level

➢ Very good weather that day

➢ CDCH locked inside the trailer

➢ Transport at very low speed

➢ CDCH on the transport trolley ready to be tested by SU people OK

➢ Caps to protect the inner volume

➢ Wires volume isolated

Central shaft insertion

12/22

➢ Central shaft safely inserted on 27/02/2019➢ Then CDCH was put on the assembly table

for the following operations

1 2 3

➢ Inner volume open

➢ Used profile beam for handling

➢ CDCH-shaft coupling with flanges

➢ External endplatesmounted

➢ Turnbuckles connected but not loaded yet

➢ Shaft-assembly structure coupling with rotation bearings

Reinforcements and leveling

13/22

➢ Centesimal bubble level➢ Very good table leveling

by fine tuning the 4 pillars

➢ We realized that we need to strengthen the CDCH supports in the longitudinal direction by using buttresses

➢ Now the whole structure is very strong and stable

RH-T monitoring

14/22

➢ Thanks to MarcoF we connected an SCS3000 to PC used during 2018 run for the CDCH HV control

➢ Continuous monitoring of relative humidity level and temperature inside the cleanroom with notification alarms ON

➢ PSI cleanroom has a feedback control based only on T

➢ Anyway the RH level is very good➢ However we placed 2 dehumidifiers

close CDCH as safety devices• They are ON but currently not

running since air conditioning is sufficient to keep RH below 40%

Same 10 days graph

21°C

Same 10 days graph

Pisa

PSI

40%

20%

Preparation to geometry survey

15/22

➢ We prepared a set of supports to hold spherical corner cubes in a fixed and reproducible position during the surveys with laser tracker

➢ Each support is made of a cylindrical magnet glued to a ring with a spherical seat

➢ We used cyanoacrylate glue for all the bondings

➢ We made some stress tests to check the bonding strength before gluing the supports on CDCH spokes

We also placed 4 supports in the 4 corners of the assembly table as reference

For all the 12 spokes of both

endplates

Laser tracker setup

16/22

➢ Survey people placed several supports for the spherical corner cubes all around the cleanroom to connect different measuring stations during the survey campaign

➢ A small spherical corner cube is used as touching device to define the endplates circle and plane and so the CDCH cylindrical shape (axis, length)• Also at inner radii to

check the spokes deformation

Wall

Ground

Frame

Endplate circles

This configuration will be used to have a live measurement of the changing CDCH length during the stretching procedure

Endplate planes

REMINDER➢ CDCH length set in Pisa as measured from the

external faces of the spokes was 1992.840 mm• Corresponding to +4.840 mm

➢ Parallelism ∥ between the average endplate planes: ≈ 80 μm

NEW GEOMETRY MEASUREMENT AT PSI on 07/03/2019with a different measuring tool after many handling operations (transport to PSI, extensions, shaft, insertion/extraction from COBRA➢ CDCH length: 1992.855 mm

• Corresponding to +4.855 mm➢ Angle between the 2 endplate planes: 0.006°

• Projecting this value on the outer endplate ring(arm of about 30 cm) →≈ 30 μm → compatible with ∥ measured in Pisa with CMM

➢ Offset @ inner radii: ≈ 80 μm per side

Survey results before reopening

17/22

4 measuring stations to have good optical access to the spokes

1

43

2This is the first proof that CDCH mechanics

is adequate and can sustain all the handling operations during a MEGII run

CDCH reopening

18/22

BEFORE

4 × 2 handles to safely move the 2 CF halves Plexiglass screen

to protect CDCH once opened

AFTERFirst half-shell

removal

➢ CDCH reopening on 12/03/2019

➢ Turnbuckles loading➢ Cut of the ThreeBond

glue all around the endplates + along the 2 longitudinal junctions took long time• Very good sealing

Wires tension beared by

turnbuckles

Broken wires extraction

19/22

Examples of extraction with

broken wires hooked by the same

stainless steel rod we used in Pisa

1 mm

2 mm

➢ Once CDCH opened we saw immediately 2 broken 40 μm cathodes both in L8 in the positions expected since the topology of short circuits experienced during 2018 run

➢ Broken wires extraction on 13-14/03/2019• CDCH shortening by 1 mm for safety

Setup for broken wires

extraction

First look at the breaking points

20/22

➢ Wires portions just extracted immediately seen with optical microscope

➢ 2 examples of breaking point➢ Samples will be sent to metallurgy

experts for in-depth analyses

➢ NO mechanical breakings• Flat wire ends (NO ogive) with corrosion points nearby (rest of the wire seems good): same seen in Pisa

➢ Hypothesis• Old weak/corrosion points since RH always kept at low level with He inside wires volume

Current status

21/22

➢ CDCH stretched by +𝟓𝟎𝟎 𝛍𝐦with respect to 2018 run• We will check the status

of this first stress test at our return from Japan

➢ CDCH temporarily sealed with CF + Al tape

➢ ≈ 200 ccm Nitrogen flushing• Safety

reason• RH level

< 40%

BEFORE

AFTER

Gas outlet

Gas inlet

Same configuration of future full

HV test

12 shorts remaining on L9, L8, L7, L6

➢ IN THE LAST 2 MONTHS: all CDCH hardware activities are on schedule up to now• Extraction from COBRA + endcaps disassembling• PSI cleanroom preparation + central shaft insertion• First geometry survey @ PSI: confirmation that CDCH mechanics is adequate• Reopening operations• Broken wires extraction and first investigations

o Hypothesis: old weak/corrosion points since RH always kept at low level with He inside wires volume➢ NEXT: stretching operations on whole April starting at our return from Japan

• Crucial moment for CDCH future• PROCEDURE

1. Stretching to reach good electrostatic stability @ working point2. Then over-stretching for about 1 week to find other possible weak wires

• Exploiting surveys with laser tracker to live-check CDCH geometryo Full HV tests exploiting all the electronicso CF mounted and CDCH temporarily sealed with Al tape and N inside

• IF OK we can be ready for the new (definitive we hope…) closing operations in early Mayo On time for the new insertion in COBRA and 2019 run

Conclusions & next steps

22/22

THANKSFOR YOUR ATTENTION