Transcript QC Procedures

QC procedures at Pol.Hi.Tech.
D.Bettoni, G.Cibinetto, S.Morganti,
Luca Boni, Alfredo Pagano
Ferrara Workshop
May 26, 2003
Introduction
• QC procedures at Pol.Hi.Tech. (PHT) have been discussed
and (almost completely) defined in various meetings with
the company.
• Test equipment to be supplied partly by INFN, must be
accepted by the company.
• Acceptance criteria to be defined together with PHT.
Outline
• General infrastructure
• Barcode labelling
• Inspection of profiles
– Mechanical
– Graphite coating
– Resistivity Measurement
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Inspection of jackets, endcaps, circuit cards
Gas tightness (leak test)
Wire check
Wire-cathode distance measurement
HV conditioning and plateau measurement
Long range tests
General Infrastructure
• QC data and other relevant information collected by hand
or, whenever possible, automatically with several DAQ
stations.
• Labview will be used to write the DAQ software and
design the interface.
• The DAQ stations will be operated by physicists on shift
and/or PHT personnel.
• All DAQ stations will be on a wireless LAN.
• The DAQ station output will be simple text files.
• Local production database will be available on site.
• Data files will be transferred every day to an outside server
to be imported in the official offsite LST database.
DAQ and Test Stations
• Dedicated Stations
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Resistivity measurement
Tube/Spool association
HV Conditioning and Plateau
Long term tests
• 1-2 General purpose station(s)
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Visual Graphite inspection
Gas tightness
Wire position
Capacitance
Local Production Database
• Linux chosen as platform
• Relational DB (my SQL, postGREP SQL ...)
• Each Station will send files to a central server after each
operation
• Server will read files into the DB once a day
• Raw data will be sent outside each day
Barcode labelling
• The idea is to use barcode labels to identify the relevant
parts that make up a tube as well as the tube itself.
• Barcodes will also be used to enter the results of some QC
tests, e.g. the defects found in the graphite coating.
• Barcode labels will show also a number, to make it easier
for the operator to look at.
Inspection of Profiles
• Mechanical. All profiles checked by Minadek.
Profiles checked on a sampling basis by PHT and
measured in Padova.
• Graphite coating. Visual check. Big defects get
corrected. Small, acceptable defects recorded
along with their positions.
• Resistivity measurement. Resistivity on the
bottom of the profiles will be measured
automatically by means of a probe. Measurements
will be taken at 50 cm intervals. Tubes accepted if
resistivity within a predefined range. Acceptance
criteria to be defined together with PHT.
Inspection of parts
• Jackets. Check for mechanical integrity and that they have
the correct dimensions. Done on a sampling basis after
production.
• Endcaps. Visual check of electrodes and gas inlets to make
sure they are in good integrity.
• Circuit cards. Visually check for cold solder joints and
sharp wire ends. Circuit is then checked for proper
continuity.
Parts are cleaned by ultrasound at PHT.
Gas Tightness
Gas leakage test is performed by completely submerging the
tubes in water at 15-20 mbar overpressure. Less than 1 small
bubble per minute is required. Leaking tubes are fixed with
PVC glue if possible and tested again. If accepted, the
information that the tube has been repaired will be registered
and the position in which the repair has occured will be
clearly marked. Tubes exceeding the 1 small bubble per
minute limit will be rejected.
Wire check
• Wire quality. A sample of wire at the beginning of each
new spool will be sent to Princeton to be checked
(mechanical, diameter, etc.). Track will be kept of which
wires will be used in each tube.
• Wire position. Possibility being considered to measure the
wire position by means of a camera.
• Wire connection and tension. Capacitance measurement at
the end, to make sure everything is OK after all the
handling etc.
HV conditioning, plateau, long range tests
• Two test stations will be set up at PHT: one for HV
conditioning and plateau measurement, one for long range
tests.
• These tests will be done with the ternary gas mixture:
88 % CO2, 9.5 % Isobuthane, 2.5 % Ar.
• The long range tests will be carried out with the tubes in
the box which will be used for shipping the tubes to the
U.S.
• Specifications for the plateau will be defined after plateaux
are measured on prototypes in Ferrara and Princeton.
HV conditioning
7 day conditioning procedure:
• 1 day to flow 6 gas volumes
• 8 hours to 1 day to reach 2500 V.
• 8 hours to 1 day to go from 2500 V to maximum voltage.
Tubes drawing more than 5 A will be rejected
• Keep 4 days at maximum voltage. The current drawn must not exceed
2 A for the first day and 100 nA for the remaining 3 days. Tubes
failing these tests are rejected.
Long range tests
Each tube will be kept at the maximum operating voltage for a period
of thirty days, during which the current drawn by the tube must not exceed
100 nA for more than 5 % of the time it is monitored. In addition no
observed activity allowed in the second half of the history.
Summary
• QC procedure at PHT well defined and agreed upon with
the company.
• Still a few questions to be addressed.
• Need to purchase equipment to carry out tests at PHT.
• Work is beginning to set up the general infrastructure and
DAQ systems and to design the two test stations.